Near infrared spectroscopy for the nondestructive estimation of clear wood properties of Pinus taeda L. from the southern United States

Treesearch

Laurence R. Schimleck; P. David Jones; Alexander Clark; Richard F. Daniels; Gary F. Peter

2005-01-01

The estimation of specific gravity (SG), modulus of elasticity (MOE), and modulus of rupture (MOR) of loblolly pine (Pinus taeda L.) clear wood samples from a diverse range of sites across the southern United States was investigated using near infrared (NIR) spectroscopy. NIR spectra were obtained from the radial and cross sectional (original, rough...

Effect of oxalic acid pretreatment of wood chips on manufacturing medium-density fiberboard

Treesearch

Xianjun Li; Zhiyong Cai; Eric Horn; Jerrold E. Winandy

2011-01-01

The main objective of this study was to evaluate the effect of oxalic acid (OA) wood chips pretreatment prior to refining, which is done to reduce energy used during the refining process. Selected mechanical and physical performances of medium-density fiberboard (MDF) – internal bonding (IB), modulus of elasticity (MOE), modulus of rupture (MOR), water absorption (WA)...

The effect of woven and non-woven fiber structure on mechanical properties polyester composite reinforced kenaf

NASA Astrophysics Data System (ADS)

Ratim, S.; Bonnia, N. N.; Surip, S. N.

2012-07-01

The effects of woven and non-woven kenaf fiber on mechanical properties of polyester composites were studied at different types of perform structures. Composite polyester reinforced kenaf fiber has been prepared via hand lay-up process by varying fiber forms into plain weave, twill and mats structure. The reinforcing efficiency of different fiber structure was compared with control of unreinforced polyester sample. It was found that the strength and stiffness of the composites are largely affected by fiber structure. A maximum value for tensile strength of composite was obtained for twill weave pattern of fiber structure while no significant different for plain weave and mat structure. The elastic modulus of composite has shown some improvement on plain and twill weave pattern. Meanwhile, lower value of modulus elasticity achieved by mats structure composite as well as control sample. The modulus of rupture and impact resistance were also analyzed. The improvement of modulus of rupture value can be seen on plain and twill weave pattern. However impact resistance doesn't show significant improvement in all types of structure except for mat fiber. The mechanical properties of kenaf fiber reinforced polyester composite found to be increased with woven and non-woven fiber structures in composite.

Small Sample Properties of Asymptotically Efficient Estimators of the Parameters of a Bivariate Gaussian–Weibull Distribution

Treesearch

Steve P. Verrill; James W. Evans; David E. Kretschmann; Cherilyn A. Hatfield

2012-01-01

Two important wood properties are stiffness (modulus of elasticity or MOE) and bending strength (modulus of rupture or MOR). In the past, MOE has often been modeled as a Gaussian and MOR as a lognormal or a two or three parameter Weibull. It is well known that MOE and MOR are positively correlated. To model the simultaneous behavior of MOE and MOR for the purposes of...

The influence of juvenile wood content on shear parallel, compression,and tension perpendicular to grain strength and mode I fracture toughness of loblolly pine at various ring orientation

Treesearch

David E. Kretschmann

2008-01-01

Forest products from improved trees grown on managed plantations and harvested in short rotations will contain higher proportions of juvenile wood than in current harvests. More information is needed on the influence of juvenile wood on lumber properties. Most information developed to date has concentrated on ultimate tensile stress, modulus of rupture, and modulus of...

Maximum likelihood estimation of the parameters of a bivariate Gaussian-Weibull distribution from machine stress-rated data

Treesearch

Steve P. Verrill; David E. Kretschmann; James W. Evans

2016-01-01

Two important wood properties are stiffness (modulus of elasticity, MOE) and bending strength (modulus of rupture, MOR). In the past, MOE has often been modeled as a Gaussian and MOR as a lognormal or a two- or threeparameter Weibull. It is well known that MOE and MOR are positively correlated. To model the simultaneous behavior of MOE and MOR for the purposes of wood...

Reliability Implications in Wood Systems of a Bivariate Gaussian-Weibull Distribution and the Associated Univariate Pseudo-truncated Weibull

Treesearch

Steve P. Verrill; James W. Evans; David E. Kretschmann; Cherilyn A. Hatfield

2014-01-01

Two important wood properties are the modulus of elasticity (MOE) and the modulus of rupture (MOR). In the past, the statistical distribution of the MOE has often been modeled as Gaussian, and that of the MOR as lognormal or as a two- or three-parameter Weibull distribution. It is well known that MOE and MOR are positively correlated. To model the simultaneous behavior...

Effects of steam treatment on bending properties and chemical composition of moso bamboo (Phyllostachys pubescens)

Treesearch

R. J. Zhao; Z. H. Jiang; C. Hse; T. Shupe

2010-01-01

Effects of temperature (25, 160 and 200 °C) and time (15 and 30 min) of steam treatment on the mechanical and chemical characteristics of moso bamboo were studied. The modulus of rupture (MOR) and modulus of elasticity (MOE) of the outer culm were at least 2.4 and 2.2 times respectively greater than those of the inner culm. Temperature and time had no effect on bending...

Development of lightweight concrete mixes for construction industry at the state of Arkansas

NASA Astrophysics Data System (ADS)

Almansouri, Mohammed Abdulwahab

As the construction industry evolved, the need for more durable, long lasting infrastructure increased. Therefore, more efforts have been put to find new methods to improve the properties of the concrete to prolong the service life of the structural elements. One of these methods is the use of lightweight aggregate as an internal curing agent to help reducing self-desiccation and shrinkage. This research studied the effects of using locally available lightweight aggregate (expanded clay), as a partial replacement of normal weight aggregate in the concrete matrix. The concrete mixtures contained lightweight aggregate with a replacement percentage of 12.5, 25, 37.5, and 50 percent by volume. Fresh properties as well as compressive strength, modulus of rupture, and drying shrinkage were measured. While was effective in reducing drying shrinkage, the use of lightweight aggregate resulted in slightly reducing both the compressive strength and modulus of rupture.

Tensile and creep rupture properties of (16) uncoated and (2) coated engineering alloys at elevated temperatures

NASA Technical Reports Server (NTRS)

Fritz, L. J.; Koster, W. P.

1977-01-01

Sixteen test materials were supplied by NASA-Lewis Research Center as wrought bar or cast remelt stock. The cast remelt stock was cast into test blanks with two such materials being also evaluated after Jocoat coating was applied. Mechanical properties evaluated included tensile, modulus of elasticity, Poisson's Ratio, creep properties and creep rupture strength. Tests were conducted at temperatures applicable to the service temperature of the various alloys. This range extended from room temperature to 1000 C.

Do xylem fibers affect vessel cavitation resistance?

PubMed

Jacobsen, Anna L; Ewers, Frank W; Pratt, R Brandon; Paddock, William A; Davis, Stephen D

2005-09-01

Possible mechanical and hydraulic costs to increased cavitation resistance were examined among six co-occurring species of chaparral shrubs in southern California. We measured cavitation resistance (xylem pressure at 50% loss of hydraulic conductivity), seasonal low pressure potential (P(min)), xylem conductive efficiency (specific conductivity), mechanical strength of stems (modulus of elasticity and modulus of rupture), and xylem density. At the cellular level, we measured vessel and fiber wall thickness and lumen diameter, transverse fiber wall and total lumen area, and estimated vessel implosion resistance using (t/b)(h)(2), where t is the thickness of adjoining vessel walls and b is the vessel lumen diameter. Increased cavitation resistance was correlated with increased mechanical strength (r(2) = 0.74 and 0.76 for modulus of elasticity and modulus of rupture, respectively), xylem density (r(2) = 0.88), and P(min) (r(2) = 0.96). In contrast, cavitation resistance and P(min) were not correlated with decreased specific conductivity, suggesting no tradeoff between these traits. At the cellular level, increased cavitation resistance was correlated with increased (t/b)(h)(2) (r(2) = 0.95), increased transverse fiber wall area (r(2) = 0.89), and decreased fiber lumen area (r(2) = 0.76). To our knowledge, the correlation between cavitation resistance and fiber wall area has not been shown previously and suggests a mechanical role for fibers in cavitation resistance. Fiber efficacy in prevention of vessel implosion, defined as inward bending or collapse of vessels, is discussed.

Design prediction for long term stress rupture service of composite pressure vessels

NASA Technical Reports Server (NTRS)

Robinson, Ernest Y.

1992-01-01

Extensive stress rupture studies on glass composites and Kevlar composites were conducted by the Lawrence Radiation Laboratory beginning in the late 1960's and extending to about 8 years in some cases. Some of the data from these studies published over the years were incomplete or were tainted by spurious failures, such as grip slippage. Updated data sets were defined for both fiberglass and Kevlar composite stand test specimens. These updated data are analyzed in this report by a convenient form of the bivariate Weibull distribution, to establish a consistent set of design prediction charts that may be used as a conservative basis for predicting the stress rupture life of composite pressure vessels. The updated glass composite data exhibit an invariant Weibull modulus with lifetime. The data are analyzed in terms of homologous service load (referenced to the observed median strength). The equations relating life, homologous load, and probability are given, and corresponding design prediction charts are presented. A similar approach is taken for Kevlar composites, where the updated stand data do show a turndown tendency at long life accompanied by a corresponding change (increase) of the Weibull modulus. The turndown characteristic is not present in stress rupture test data of Kevlar pressure vessels. A modification of the stress rupture equations is presented to incorporate a latent, but limited, strength drop, and design prediction charts are presented that incorporate such behavior. The methods presented utilize Cartesian plots of the probability distributions (which are a more natural display for the design engineer), based on median normalized data that are independent of statistical parameters and are readily defined for any set of test data.

Development of nondestructive methods for measurement of slab thickness and modulus of rupture in concrete pavements.

DOT National Transportation Integrated Search

2005-01-01

This report describes work to develop non-destructive testing methods for concrete pavements. Two methods, for pavement thickness and in-place strength estimation, respectively, were developed and evaluated. The thickness estimation method is based o...

Improved silicon nitride for advanced heat engines

NASA Technical Reports Server (NTRS)

Yeh, H. C.; Wimmer, J. M.; Huang, H. H.; Rorabaugh, M. E.; Schienle, J.; Styhr, K. H.

1985-01-01

The AiResearch Casting Company baseline silicon nitride (92 percent GTE SN-502 Si sub 3 N sub 4 plus 6 percent Y sub 2 O sub 3 plus 2 percent Al sub 2 O sub 3) was characterized with methods that included chemical analysis, oxygen content determination, electrophoresis, particle size distribution analysis, surface area determination, and analysis of the degree of agglomeration and maximum particle size of elutriated powder. Test bars were injection molded and processed through sintering at 0.68 MPa (100 psi) of nitrogen. The as-sintered test bars were evaluated by X-ray phase analysis, room and elevated temperature modulus of rupture strength, Weibull modulus, stress rupture, strength after oxidation, fracture origins, microstructure, and density from quantities of samples sufficiently large to generate statistically valid results. A series of small test matrices were conducted to study the effects and interactions of processing parameters which included raw materials, binder systems, binder removal cycles, injection molding temperatures, particle size distribution, sintering additives, and sintering cycle parameters.

Stress Rupture Behavior of Silicon Carbide Coated, Low Modulus Carbon/Carbon Composites. M.S. Thesis

NASA Technical Reports Server (NTRS)

Rozak, Gary A.; Wallace, John F.

1988-01-01

The disadvantages of carbon-carbon composites, in addition to the oxidation problem, are low thermal expansion, expensive fabrication procedures, and poor off axis properties. The background of carbon-carbon composites, their fabrication, oxidation, oxidation protection and mechanical testing in flexure are discussed.

Evaluation of Mechanical Properties of Plywood Treated with a new Wood Preservative (CEB) Chemical

NASA Astrophysics Data System (ADS)

Kalawate, Aparna; Shahoo, Shadhu Charan; Khatua, Pijus Kanti; Das, Himadri Sekhar

2017-04-01

The objective of this study was to explore the physical and mechanical properties of the plywood made with phenolic glue and rubber wood as core veneer with CEB as a wood preservative. The studied properties were glue shear strength in dry, wet mycological, modulus of elasticity, modulus of rupture and tensile strength in parallel to grain direction as per IS:1734 part-4, 11 and 9 (1983) respectively. Results of the above mentioned tests were compared with the prescribed values given in IS 710-2010 and results revealed that samples conformed the prescribed values.

Molecular dynamics modeling of PPTA crystallite mechanical properties in the presence of defects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mercer, Brian; Zywicz, Edward; Papadopoulos, Panayiotis

Here, the mechanical properties of PPTA crystallites, the fundamental building blocks of aramid polymer fibers such as Kevlar® and Twaron®, are studied here using molecular dynamics simulations. The ReaxFF interatomic potential is employed to study crystallite failure via covalent and hydrogen bond rupture in constant strain-rate tensile loading simulations. Emphasis is placed on analyzing how chain-end defects in the crystallite influence its mechanical response and fracture strength. Chain-end defects are found to affect the behavior of nearby chains in a region of the PPTA crystallite that is small relative to the typical crystallite size in manufactured aramid fibers. The centralmore » Csingle bondN bond along the backbone chain is identified as the weakest in the PPTA polymer chain backbone in dynamic strain-to-failure simulations of the crystallite. It is found that clustering of chain-ends leads to reduced crystallite strength and crystallite failure via hydrogen bond rupture and chain sliding, whereas randomly scattered defects impact the strength less and failure is by covalent bond rupture and chain scission. The axial crystallite modulus increases with increasing chain length and is independent of chain-end defect locations. On the basis of these findings, a theoretical model is proposed to predict the axial modulus as a function of chain length.« less

Molecular dynamics modeling of PPTA crystallite mechanical properties in the presence of defects

DOE PAGES

Mercer, Brian; Zywicz, Edward; Papadopoulos, Panayiotis

2017-03-11

Here, the mechanical properties of PPTA crystallites, the fundamental building blocks of aramid polymer fibers such as Kevlar® and Twaron®, are studied here using molecular dynamics simulations. The ReaxFF interatomic potential is employed to study crystallite failure via covalent and hydrogen bond rupture in constant strain-rate tensile loading simulations. Emphasis is placed on analyzing how chain-end defects in the crystallite influence its mechanical response and fracture strength. Chain-end defects are found to affect the behavior of nearby chains in a region of the PPTA crystallite that is small relative to the typical crystallite size in manufactured aramid fibers. The centralmore » Csingle bondN bond along the backbone chain is identified as the weakest in the PPTA polymer chain backbone in dynamic strain-to-failure simulations of the crystallite. It is found that clustering of chain-ends leads to reduced crystallite strength and crystallite failure via hydrogen bond rupture and chain sliding, whereas randomly scattered defects impact the strength less and failure is by covalent bond rupture and chain scission. The axial crystallite modulus increases with increasing chain length and is independent of chain-end defect locations. On the basis of these findings, a theoretical model is proposed to predict the axial modulus as a function of chain length.« less

Panel Board From Coconut Fibre And Pet Bottle

NASA Astrophysics Data System (ADS)

Ngadiman, Norhayati; Kaamin, Masiri; Abd. Kadir, Aslila; Sahat, Suhaila; Zaini, Aziza; Raihana Nor Zentan, Siti; Ain Ahmad, Nur; Amran, Wan Haizatul Aisyhah Wan

2018-03-01

The rate of global deforestation and its impact on the environment has led particle board manufacture to search for alternative feedstock, especially in countries where wood is less available compared to other cellulosic natural product. Based on the properties of coconut fibre and PET bottle, these two materials can be recycle as raw material for manufacture of panel board. As for this study, the coconut fibre were used as the filler and PET bottle as outer lining of the panel board. Two types of coconut fibre were used which are grinding and un-grinding coconut fibre. At first, the coconut fibre are undergoes softening, grinding, drying and sieving process, while PET bottle was cleaning, shredding, sieving before compacted using hydraulic hot press machine. There are four types of testing that been carried out which are swelling, water absorption, Modulus of Elasticity (MOE) and Modulus of Rupture (MOR). The result show the conventional board has the highest value for MOE test, so it's indicate that the conventional board is less strength from the coconut fibre board. As for water absorption test, the average water absorption of coconut fibre based panel board is less than conventional board. Overall, the coconut fibre board is better than conventional panel board because coconut fibre board are less swelling, has low water absorption, high modulus of rupture and low modulus of elasticity. Based on the finding, this coconut fibre panel board has potential as a stronger and long-lasting panel board than the conventional board in the market. Other than that, the panel also have their own aesthetic value since the recycled plastic bottle used as outer lining is colourful and giving aesthetic value.

Micromechanical models to guide the development of synthetic ‘brick and mortar’ composites

NASA Astrophysics Data System (ADS)

Begley, Matthew R.; Philips, Noah R.; Compton, Brett G.; Wilbrink, David V.; Ritchie, Robert O.; Utz, Marcel

2012-08-01

This paper describes a micromechanical analysis of the uniaxial response of composites comprising elastic platelets (bricks) bonded together with thin elastic perfectly plastic layers (mortar). The model yields closed-form results for the spatial variation of displacements in the bricks as a function of constituent properties, which can be used to calculate the effective properties of the composite, including elastic modulus, strength and work-to-failure. Regime maps are presented which indicate critical stresses for failure of the bricks and mortar as a function of constituent properties and brick architecture. The solution illustrates trade-offs between elastic modulus, strength and dissipated work that are a result of transitions between various failure mechanisms associated with brick rupture and rupture of the interfaces. Detailed scaling relationships are presented with the goal of providing material developers with a straightforward means to identify synthesis targets that balance competing mechanical behaviors and optimize material response. Ashby maps are presented to compare potential brick and mortar composites with existing materials, and identify future directions for material development.

Revealing stiffening and brittling of chronic myelogenous leukemia hematopoietic primary cells through their temporal response to shear stress.

PubMed

Laperrousaz, B; Berguiga, L; Nicolini, F E; Martinez-Torres, C; Arneodo, A; Satta, V Maguer; Argoul, F

2016-06-02

Cancer cell transformation is often accompanied by a modification of their viscoelastic properties. When capturing the stress-to-strain response of primary chronic myelogenous leukemia (CML) cells, from two data sets of CD34+ hematopoietic cells isolated from healthy and leukemic bone marrows, we show that the mean shear relaxation modulus increases upon cancer transformation. This stiffening of the cells comes along with local rupture events, detected as reinforced sharp local maxima of this modulus, suggesting that these cancer cells respond to a local mechanical stress by a cascade of local brittle failure events.

Revealing stiffening and brittling of chronic myelogenous leukemia hematopoietic primary cells through their temporal response to shear stress

NASA Astrophysics Data System (ADS)

Laperrousaz, B.; Berguiga, L.; Nicolini, F. E.; Martinez-Torres, C.; Arneodo, A.; Maguer Satta, V.; Argoul, F.

2016-06-01

Cancer cell transformation is often accompanied by a modification of their viscoelastic properties. When capturing the stress-to-strain response of primary chronic myelogenous leukemia (CML) cells, from two data sets of CD34+ hematopoietic cells isolated from healthy and leukemic bone marrows, we show that the mean shear relaxation modulus increases upon cancer transformation. This stiffening of the cells comes along with local rupture events, detected as reinforced sharp local maxima of this modulus, suggesting that these cancer cells respond to a local mechanical stress by a cascade of local brittle failure events.

Investigating the impact of spatial priors on the performance of model-based IVUS elastography

PubMed Central

Richards, M S; Doyley, M M

2012-01-01

This paper describes methods that provide pre-requisite information for computing circumferential stress in modulus elastograms recovered from vascular tissue—information that could help cardiologists detect life-threatening plaques and predict their propensity to rupture. The modulus recovery process is an ill-posed problem; therefore additional information is needed to provide useful elastograms. In this work, prior geometrical information was used to impose hard or soft constraints on the reconstruction process. We conducted simulation and phantom studies to evaluate and compare modulus elastograms computed with soft and hard constraints versus those computed without any prior information. The results revealed that (1) the contrast-to-noise ratio of modulus elastograms achieved using the soft prior and hard prior reconstruction methods exceeded those computed without any prior information; (2) the soft prior and hard prior reconstruction methods could tolerate up to 8 % measurement noise; and (3) the performance of soft and hard prior modulus elastogram degraded when incomplete spatial priors were employed. This work demonstrates that including spatial priors in the reconstruction process should improve the performance of model-based elastography, and the soft prior approach should enhance the robustness of the reconstruction process to errors in the geometrical information. PMID:22037648

Suitability of live and fire-killed small-diameter ponderosa and lodgepole pine trees for manufacturing a new structural wood composite.

PubMed

Linton, J M; Barnes, H M; Seale, R D; Jones, P D; Lowell, E C; Hummel, S S

2010-08-01

Finding alternative uses for raw material from small-diameter trees is a critical problem throughout the United States. In western states, a lack of markets for small-diameter ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta) can contribute to problems associated with overstocking. To test the feasibility of producing structural composite lumber (SCL) beams from these two western species, we used a new technology called steam-pressed scrim lumber (SPSL) based on scrimming technology developed in Australia. Both standing green and fire-killed ponderosa and lodgepole pine logs were used in an initial test. Fire-killed logs of both species were found to be unsuitable for producing SPSL but green logs were suitable for producing SPSL. For SPSL from green material, ponderosa pine had significantly higher modulus of rupture and work-to-maximum load values than did SPSL from lodgepole pine. Modulus of elasticity was higher for lodgepole pine. The presence of blows was greater with lodgepole pine than with ponderosa. Blows had a negative effect on the mechanical properties of ponderosa pine but no significant effect on the mechanical properties of SPSL from lodgepole pine. An evaluation of non-destructive testing methods showed that X-ray could be used to determine low density areas in parent beams. The use of a sonic compression wave tester for NDE evaluation of modulus of rupture showed some promise with SPSL but requires further research. (c) 2010 Elsevier Ltd. All rights reserved.

Effect of silvicultural practice and wood type on loblolly pine particleboard and medium density fiberboard properties

Treesearch

Todd F. Shupe; Chung Y. Hse; Elvin T. Choong; Leslie H. Groom

1999-01-01

he objective of this study was to determine the effect of five different silvicultural strategies and wood type on mechanical and physical properties of loblolly pine (Pinus taeda L.) particleboard and fiberboard. The furnish was prepared in an unconventional manner from innerwood and outerwood veneer for each stand. Modulus of rupture (MOR)...

Nose Fairing Modeling and Simulation to Support Trident II D5 Lifecycle Extension

DTIC Science & Technology

2013-09-01

Rupture Flexural Modulus Flexural Yield strength Compressive Yield strength Poissons Ratio Machinabi lily Shear strength Impact Work to...Categories: Ceramic; Glass; Glass Fiber , other Engineeting Material; C<>mposite Rbers Material Notes: Used as a reinforcing agent in fiber glass compos~es...MATWEB AMERICAN SITKA SPRUCE WOOD .......................35 APPENDIX B. MATWEB E–GLASS FIBER , GENERIC ......................................37 APPENDIX

Development of Ti-Nb-Zr alloys with high elastic admissible strain for temporary orthopedic devices.

PubMed

Ozan, Sertan; Lin, Jixing; Li, Yuncang; Ipek, Rasim; Wen, Cuie

2015-07-01

A new series of beta Ti-Nb-Zr (TNZ) alloys with considerable plastic deformation ability during compression test, high elastic admissible strain, and excellent cytocompatibility have been developed for removable bone tissue implant applications. TNZ alloys with nominal compositions of Ti-34Nb-25Zr, Ti-30Nb-32Zr, Ti-28Nb-35.4Zr and Ti-24.8Nb-40.7Zr (wt.% hereafter) were fabricated using the cold-crucible levitation technique, and the effects of alloying element content on their microstructures, mechanical properties (tensile strength, yield strength, compressive yield strength, Young's modulus, elastic energy, toughness, and micro-hardness), and cytocompatibilities were investigated and compared. Microstructural examinations revealed that the TNZ alloys consisted of β phase. The alloy samples displayed excellent ductility with no cracking, or fracturing during compression tests. Their tensile strength, Young's modulus, elongation at rupture, and elastic admissible strain were measured in the ranges of 704-839 MPa, 62-65 GPa, 9.9-14.8% and 1.08-1.31%, respectively. The tensile strength, Young's modulus and elongation at rupture of the Ti-34Nb-25Zr alloy were measured as 839 ± 31.8 MPa, 62 ± 3.6 GPa, and 14.8 ± 1.6%, respectively; this alloy exhibited the elastic admissible strain of approximately 1.31%. Cytocompatibility tests indicated that the cell viability ratios (CVR) of the alloys are greater than those of the control group; thus the TNZ alloys possess excellent cytocompatibility. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

A performance-based evaluation of chemically similar (carbonate) tempers from Late Prehistoric (AD 1200-1700) Ohio: Implications for human selection and production of ceramic technology

PubMed Central

Spurlock, Linda B.; Fisch, Michael

2018-01-01

Purpose This study was designed to assess the mechanical properties of two calcium carbonate tempers, limestone and burnt shell. These tempers have been previously compared, in separate studies, to silicate-based grit or sand temper and, relative to the latter, are assumed to possess similar mechanical properties. However, their simultaneous use at the Morrison Village site begs the question: do these two calcium carbonate tempers indeed possess similar mechanical properties? In order to assess their performance characteristics, a side-by-side controlled experimental test was conducted to determine the degree of similarity in providing increased vessel strength and toughness. Methods Standardized ceramic test samples were systematically prepared via a set, explicit protocol. An Instron Series IX universal testing machine configured with a four-point flexural test jig was used to perform a flexural strength test of the test samples. The Instron load and deflection data were used to calculate three values related to mechanical performance: peak load, modulus of rupture, and modulus of elasticity. Results All four comparative tests clearly show substantial differences in peak load, modulus of rupture, and modulus of elasticity. These differences are statistically significant for each performance attribute in every iteration of the experiment and as indicated by Mann-Whitney U Tests. Conclusions These results do not support the hypothesis that limestone and burnt shell offer the same performance characteristics. These results have implications for our understanding of prehistoric human selection of temper and the evolution of ceramic technology. Although both carbonate-based tempers are currently thought to offer the same benefits during the initial phase of pottery production, their contrasting post firing properties would have provided distinct benefits in different contexts. Future assessments of the Morrison Village ceramic assemblage should focus on residue analysis, or other functional indicators, to support or falsify this hypothesis. PMID:29579085

Use of regional mechanical properties of abdominal aortic aneurysms to advance finite element modeling of rupture risk.

PubMed

Tierney, Áine P; Callanan, Anthony; McGloughlin, Timothy M

2012-02-01

To investigate the use of regional variations in the mechanical properties of abdominal aortic aneurysms (AAA) in finite element (FE) modeling of AAA rupture risk, which has heretofore assumed homogeneous mechanical tissue properties. Electrocardiogram-gated computed tomography scans from 3 male patients with known infrarenal AAA were used to characterize the behavior of the aneurysm in 4 different segments (posterior, anterior, and left and right lateral) at maximum diameter and above the infrarenal aorta. The elasticity of the aneurysm (circumferential cyclic strain, compliance, and the Hudetz incremental modulus) was calculated for each segment and the aneurysm as a whole. The FE analysis inclusive of prestress (pre-existing tensile stress) produced a detailed stress pattern on each of the aneurysm models under pressure loading. The 4 largest areas of stress in each region were considered in conjunction with the local regional properties of the segment to define a specific regional prestress rupture index (RPRI). In terms of elasticity, there were average reductions of 68% in circumferential cyclic strain and 63% in compliance, with a >5-fold increase in incremental modulus, between the healthy and the aneurysmal aorta for each patient. There were also regional variations in all elastic properties in each individual patient. The average difference in total stress inclusive of prestress was 59%, 67%, and 15%, respectively, for the 3 patients. Comparing the strain from FE models with the CT scans revealed an average difference in strain of 1.55% for the segmented models and 3.61% for the homogeneous models, which suggests that the segmented models more accurately reflect in vivo behavior. RPRI values were calculated for each segment for all patients. A greater understanding of the local material properties and their use in FE models is essential for greater accuracy in rupture prediction. Quantifying the regional behavior will yield insight into the changes in patient-specific aneurysms and increase understanding about the progression of aneurysmal disease.

Experimental shear strength of unchecked solid-sawn Douglas-fir

Treesearch

D. R. Rammer; L. A. Soltis; P. K. Lebow

This report presents experimental results of modulus of rupture and shear strength tests on unsplit, green, sawn Douglas-fir lumber. Five different size-matched specimens, ranging from nominal 2-by 4-in (standard 38- by 89-mm) to nominal 4- by 14-in (standard 95-by 343-mm), were tested in third-point bending and five-point beam shear. A total of 120 bending and 160...

Evaluation of the effects of a freeze/thaw environment on cellular glass

NASA Technical Reports Server (NTRS)

Frickland, P.; Cleland, E.; Hasegawa, T.

1981-01-01

Using the evaluation criteria of water vapor permeability and conformability, a protective butylrubber/silicone conformal coating system was selected for use on Foamglas substrates in a freeze/thaw environment. The selection of a specific freeze/thaw cycle which closely models field conditions is discussed. A sampling plan is described which allows independent evaluation of the effects of conformal coatings, cycle number and location within the environmental chamber. The results of visual examination, measurement of density, modulus of rupture and Young's modulus are reported. Based upon statistical evaluation of the experimental results, it is concluded that no degradation in mechanical properties of either coated or uncoated Foamglas occurred within the duration of the test (53 freeze/thaw cycles).

Hooke's Law and the Stiffness of a Plastic Spoon

NASA Astrophysics Data System (ADS)

Pestka, Kenneth A.; Warren, Cori

2012-11-01

The study of elastic properties of solids is essential to both physics and engineering. Finding simple, easy-to-visualize examples to demonstrate these concepts is often difficult. In a previous article written by one of us (KAPII), a simple method for determining Youngs modulus using marshmallows was given. In this article we will illustrate another method to explore elastic properties of everyday materials. This experiment uses a common plastic spoon exposed to a transverse force in order to determine the stiffness constant, yield point, and rupture point of the plastic spoon. In addition, much like the "Youngs Modulus of a Marshmallow" activity, this experiment visually demonstrates Hooke's law, is fun and easy to perform, and leaves a lasting impression on the students.

Quantum chemical determination of Young's modulus of lignin. Calculations on a beta-O-4' model compound.

PubMed

Elder, Thomas

2007-11-01

The calculation of Young's modulus of lignin has been examined by subjecting a dimeric model compound to strain, coupled with the determination of energy and stress. The computational results, derived from quantum chemical calculations, are in agreement with available experimental results. Changes in geometry indicate that modifications in dihedral angles occur in response to linear strain. At larger levels of strain, bond rupture is evidenced by abrupt changes in energy, structure, and charge. Based on the current calculations, the bond scission may be occurring through a homolytic reaction between aliphatic carbon atoms. These results may have implications in the reactivity of lignin especially when subjected to processing methods that place large mechanical forces on the structure.

Elasticity and anelasticity of microcrystalline aluminum samples having various deformation and thermal histories

NASA Astrophysics Data System (ADS)

Betekhtin, V. I.; Kadomtsev, A. G.; Kardashev, B. K.

2006-08-01

The effect of the amplitude of vibrational deformation on the elastic modulus and internal friction of microcrystalline aluminum samples produced by equal-channel angular pressing was studied. The samples have various deformation and thermal histories. The elastic and inelastic (microplastic) properties of the samples are investigated. As the degree of plastic deformation increases, the Young’s modulus E, the amplitude-independent decrement δi, and the microplastic flow stress σ increase. As the annealing temperature increases, the quantities δi and σ decrease noticeably and the modulus E exhibits a more complex behavior. The experimental data are discussed under the assumption that the dislocation mobility depends on both the spectrum of point defects and the internal stresses, whose level is determined by the degree of plastic deformation and the temperature of subsequent annealing. The concept of internal stresses is also used to analyze the data on the effect of the degree of deformation and annealing on the rupture strength of the samples.

Extensor indicis proprius tendon transfer using shear wave elastography.

PubMed

Lamouille, J; Müller, C; Aubry, S; Bensamoun, S; Raffoul, W; Durand, S

2017-06-01

The means for judging optimal tension during tendon transfers are approximate and not very quantifiable. The purpose of this study was to demonstrate the feasibility of quantitatively assessing muscular mechanical properties intraoperatively using ultrasound elastography (shear wave elastography [SWE]) during extensor indicis proprius (EIP) transfer. We report two cases of EIP transfer for post-traumatic rupture of the extensor pollicis longus muscle. Ultrasound acquisitions measured the elasticity modulus of the EIP muscle at different stages: rest, active extension, active extension against resistance, EIP section, distal passive traction of the tendon, after tendon transfer at rest and then during active extension. A preliminary analysis was conducted of the distribution of values for this modulus at the various transfer steps. Different shear wave velocity and elasticity modulus values were observed at the various transfer steps. The tension applied during the transfer seemed close to the resting tension if a traditional protocol were followed. The elasticity modulus varied by a factor of 37 between the active extension against resistance step (565.1 kPa) and after the tendon section (15.3 kPa). The elasticity modulus values were distributed in the same way for each patient. The therapeutic benefit of SWE elastography was studied for the first time in tendon transfers. Quantitative data on the elasticity modulus during this test may make it an effective means of improving intraoperative adjustments. Copyright © 2017 SFCM. Published by Elsevier Masson SAS. All rights reserved.

Toward tsunami early warning system in Indonesia by using rapid rupture durations estimation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Madlazim

2012-06-20

Indonesia has Indonesian Tsunami Early Warning System (Ina-TEWS) since 2008. The Ina-TEWS has used automatic processing on hypocenter; Mwp, Mw (mB) and Mj. If earthquake occurred in Ocean, depth < 70 km and magnitude > 7, then Ina-TEWS announce early warning that the earthquake can generate tsunami. However, the announcement of the Ina-TEWS is still not accuracy. Purposes of this research are to estimate earthquake rupture duration of large Indonesia earthquakes that occurred in Indian Ocean, Java, Timor sea, Banda sea, Arafura sea and Pasific ocean. We analyzed at least 330 vertical seismogram recorded by IRIS-DMC network using a directmore » procedure for rapid assessment of earthquake tsunami potential using simple measures on P-wave vertical seismograms on the velocity records, and the likelihood that the high-frequency, apparent rupture duration, T{sub dur}. T{sub dur} can be related to the critical parameters rupture length (L), depth (z), and shear modulus ({mu}) while T{sub dur} may be related to wide (W), slip (D), z or {mu}. Our analysis shows that the rupture duration has a stronger influence to generate tsunami than Mw and depth. The rupture duration gives more information on tsunami impact, Mo/{mu}, depth and size than Mw and other currently used discriminants. We show more information which known from the rupture durations. The longer rupture duration, the shallower source of the earthquake. For rupture duration greater than 50 s, the depth less than 50 km, Mw greater than 7, the longer rupture length, because T{sub dur} is proportional L and greater Mo/{mu}. Because Mo/{mu} is proportional L. So, with rupture duration information can be known information of the four parameters. We also suggest that tsunami potential is not directly related to the faulting type of source and for events that have rupture duration greater than 50 s, the earthquakes generated tsunami. With available real-time seismogram data, rapid calculation, rupture duration discriminant can be completed within 4-5 min after an earthquake occurs and thus can aid in effective, accuracy and reliable tsunami early warning for Indonesia region.« less

Studies on densification, mechanical, micro-structural and structure–properties relationship of magnesium aluminate spinel refractory aggregates prepared from Indian magnesite

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghosh, Chandrima; Ghosh, Arup; Haldar, Manas Kamal, E-mail: manashaldar@cgcri.res.in

The present work intends to study the development of magnesium aluminate spinel aggregates from Indian magnesite in a single firing stage. The raw magnesite has been evaluated in terms of chemical analysis, differential thermal analysis, thermogravimetric analysis, infrared spectroscopy, and X-ray diffraction. The experimental batch containing Indian magnesite and calcined alumina has been sintered in the temperature range of 1550 °C–1700 °C. The sintered material has been characterized in terms of physico-chemical properties like bulk density, apparent porosity, true density, relative density and thermo-mechanical/mechanical properties like hot modulus of rupture, thermal shock resistance, cold modulus of rupture and structural propertiesmore » by X-ray diffraction in terms of phase identification and evaluation of crystal structure parameters of corresponding phases by Rietveld analysis. The microstructures developed at different temperatures have been analyzed by field emission scanning electron microscope study and compositional analysis of the developed phase has been carried out by energy dispersive X-ray study. - Highlights: • The studies have been done to characterize the developed magnesium aluminate spinel. • The studies reveal correlation between refractory behavior of spinel and developed microstructures. • The studies show the values of lattice parameters of developed phases.« less

Creep and stress rupture of oxide dispersion strengthened mechanically alloyed Inconel alloy MA 754

NASA Technical Reports Server (NTRS)

Howson, T. E.; Tien, J. K.; Stulga, J. E.

1980-01-01

The creep and stress rupture behavior of the mechanically alloyed oxide dispersion strengthened nickel-base alloy MA 754 was studied at 760, 982 and 1093 C. Tensile specimens with a fine, highly elongated grain structure, oriented parallel and perpendicular to the longitudinal grain direction were tested at various stresses in air under constant load. It was found that the apparent stress dependence was large, with power law exponents ranging from 19 to 33 over the temperature range studied. The creep activation energy, after correction for the temperature dependence of the elastic modulus, was close to but slightly larger than the activation energy for self diffusion. Rupture was intergranular and the rupture ductility as measured by percentage elongation was generally low, with values ranging from 0.5 to 16 pct. The creep properties are rationalized by describing the creep rates in terms of an effective stress which is the applied stress minus a resisting stress consistent with the alloy microstructure. Values of the resisting stress obtained through a curve fitting procedure are found to be close to the values of the particle by-pass stress for this oxide dispersion strengthened alloy, as calculated from the measured oxide particle distribution.

Microstructure and physical properties of steel-ladle purging plug refractory materials

NASA Astrophysics Data System (ADS)

Long, Bin; Xu, Gui-ying; Andreas, Buhr

2017-02-01

Three different castables were prepared as steel-ladle purging-plug refractory materials: corundum-based low-cement castable (C-LCC), corundum-spinel-based low-cement castable (C-S-LCC), and no-cement corundum-spinel castable (C-S-NCC) (hydratable alumina ρ-Al2O3 bonded). The properties of these castables were characterized with regard to water demand/flow ability, cold crushing strength (CCS), cold modulus of rupture (CMoR), permanent linear change (PLC), apparent porosity, and hot modulus of rupture (HMoR). The results show the CCS/CMoR and HMoR of C-LCC and C-S-LCC are greater than those of the castable C-S-NCC. According to the microstructure analysis, the sintering effect and the bonding type of the matrix material differ among the three castables. The calcium hexaluminate (CA6) phase in the matrix of C-LCC enhances the cold and hot mechanical strengths. In the case of C-S-LCC, the CA6 and 2CaO·2MgO·14Al2O3 (C2M2A14) ternary phases generated from the matrix can greatly increase the cold and hot mechanical strengths. In the case of the no-cement castable, sintering becomes difficult, resulting in a lower mechanical strength.

Synthesis, characterization and bioactivity of a calcium-phosphate glass-ceramics obtained by the sol-gel processing method.

PubMed

Jmal, Nouha; Bouaziz, Jamel

2017-02-01

In this work, a calcium-phosphate glass-ceramics was successfully obtained by heat treatment of a mixture of 26.52 in wt.% of fluorapatite (Fap) and 73.48 in wt.% of 77S (77 SiO 2 14 CaO9 P 2 O 5 in wt.%) gel. The calcium phosphate-glass-ceramics was prepared by sol-gel process with tetraethyl orthosilicate (TEOS), triethyl phosphate (TEP), calcium nitrate and fluorapatite. The synthesized powders were characterized by some commonly used tools such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), 31 P magic angle spinning nuclear magnetic resonance (MAS-NMR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thin-film X-ray diffraction (TF-XRD). The obtained results seemed to confirm the nucleation and growth of hydroxyapatite (Hap) nano-phase in the glass. Moreover, an in-vitro evaluation of the glass-ceramic was performed. In addition, to assess its bioactive capacity, it was soaked in simulated body fluid (SBF) at different time intervals. The SEM, EDS and TF-XRD analyses showed the deposition of hydroxyapatite on the surface of the specimens after three days of immersion in SBF solution. The mechanical properties of the obtained material such as rupture strength, Vickers hardness and elastic modulus were measured. In addition, the friction coefficient of calcium phosphate-glass-ceramics was tested. The values of the composite of rupture strength (24MPa), Vickers hardness (214Hv), Young's modulus (52.3GPa), shear modulus (19GPa) and friction coefficient (0.327) were obtained. This glass-ceramics can have useful applications in dental prostheses. Indeed, this material may have promising applications for implants because of its content of fluorine, the effective protector against dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

Ultrasonically synthesized organic liquid-filled chitosan microcapsules: part 2: characterization using AFM (atomic force microscopy) and combined AFM-confocal laser scanning fluorescence microscopy.

PubMed

Mettu, Srinivas; Ye, Qianyu; Zhou, Meifang; Dagastine, Raymond; Ashokkumar, Muthupandian

2018-04-25

Atomic Force Microscopy (AFM) is used to measure the stiffness and Young's modulus of individual microcapsules that have a chitosan cross-linked shell encapsulating tetradecane. The oil filled microcapsules were prepared using a one pot synthesis via ultrasonic emulsification of tetradecane and crosslinking of the chitosan shell in aqueous solutions of acetic acid. The concentration of acetic acid in aqueous solutions of chitosan was varied from 0.2% to 25% v/v. The effect of acetic acid concentration and size of the individual microcapsules on the strength was probed. The deformations and forces required to rupture the microcapsules were also measured. Three dimensional deformations of microcapsules under large applied loads were obtained by the combination of Laser Scanning Confocal Microscopy (LSCM) with Atomic Force Microscopy (AFM). The stiffness, and hence the modulus, of the microcapsules was found to decrease with an increase in size with the average stiffness ranging from 82 to 111 mN m-1 and average Young's modulus ranging from 0.4 to 6.5 MPa. The forces required to rupture the microcapsules varied from 150 to 250 nN with deformations of the microcapsules up to 62 to 110% relative to their radius, respectively. Three dimensional images obtained using laser scanning confocal microscopy showed that the microcapsules retained their structure and shape after being subjected to large deformations and subsequent removal of the loads. Based on the above observations, the oil filled chitosan crosslinked microcapsules are an ideal choice for use in the food and pharmaceutical industries as they would be able to withstand the process conditions encountered.

Damage properties simulations of self-healing composites.

PubMed

Chen, Cheng; Ji, Hongwei; Wang, Huaiwen

2013-10-01

Self-healing materials are inspired by biological systems in which damage triggers an autonomic healing response. The damage properties of a self-healing polymer composite were investigated by numerical simulation in this paper. Unit cell models with single-edge centered crack and single-edge off-centered crack were employed to investigate the damage initiation and crack evolution by the extended finite element method (XFEM) modeling. The effect of microcapsule's Young's modulus on composites was investigated. Result indicates the microcapsule's Young's modulus has little effect on the unit cell's carrying capacity. It was found that during the crack propagation process, its direction is attracted toward the microcapsules, which makes it helpful for the microcapsules to be ruptured by the propagating crack fronts resulting in release of the healing agent into the cracks by capillary action.

The viscoelastic behavior of a composite in a thermal environment

NASA Technical Reports Server (NTRS)

Morris, D. H.; Brinson, H. F.; Griffith, W. I.; Yeow, Y. T.

1979-01-01

A proposed method for the accelerated predictions of modulus and life times for time dependent polymer matrix composite laminates is presented. The method, based on the time temperature superposition principle and lamination theory, is described in detail. Unidirectional reciprocal of compliance master curves and the shift functions needed are presented and discussed. Master curves for arbitrarily oriented unidirectional laminates are predicted and compared with experimantal results obtained from master curves generated from 15 minute tests and with 25 hour tests. Good agreement is shown. Predicted 30 deg and 60 deg unidirectional strength master curves are presented and compared to results of creep rupture tests. Reasonable agreement is demonstrated. In addition, creep rupture results for a (90 deg + or - 60 deg/90 deg) sub 2s laminate are presented.

Transesophageal echocardiographic strain imaging predicts aortic biomechanics: Beyond diameter.

PubMed

Emmott, Alexander; Alzahrani, Haitham; Alreishidan, Mohammed; Therrien, Judith; Leask, Richard L; Lachapelle, Kevin

2018-03-11

Clinical guidelines recommend resection of ascending aortic aneurysms at diameters 5.5 cm or greater to prevent rupture or dissection. However, approximately 40% of all ascending aortic dissections occur below this threshold. We propose new transesophageal echocardiography strain-imaging moduli coupled with blood pressure measurements to predict aortic dysfunction below the surgical threshold. A total of 21 patients undergoing aortic resection were recruited to participate in this study. Transesophageal echocardiography imaging of the aortic short-axis and invasive radial blood pressure traces were taken for 3 cardiac cycles. By using EchoPAC (GE Healthcare, Madison, Wis) and postprocessing in MATLAB (MathWorks, Natick, Mass), circumferential stretch profiles were generated and combined with the blood pressure traces. From these data, 2 in vivo stiffness moduli were calculated: the Cardiac Cycle Pressure Modulus and Cardiac Cycle Stress Modulus. From the resected aortic ring, testing squares were isolated for ex vivo mechanical analysis and histopathology. Each square underwent equibiaxial tensile testing to generate stress-stretch profiles for each patient. Two ex vivo indices were calculated from these profiles (energy loss and incremental stiffness) for comparison with the Cardiac Cycle Pressure Modulus and Cardiac Cycle Stress Modulus. The echo-derived stiffness moduli demonstrate positive significant covariance with ex vivo tensile biomechanical indices: energy loss (vs Cardiac Cycle Pressure Modulus: R 2  = 0.5873, P < .0001; vs Cardiac Cycle Stress Modulus: R 2  = 0.6401, P < .0001) and apparent stiffness (vs Cardiac Cycle Pressure Modulus: R 2  = 0.2079, P = .0378; vs Cardiac Cycle Stress Modulus: R 2  = 0.3575, P = .0042). Likewise, these transesophageal echocardiography-derived moduli are highly predictive of the histopathologic composition of collagen and elastin (collagen/elastin ratio vs Cardiac Cycle Pressure Modulus: R 2  = 0.6165, P < .0001; vs Cardiac Cycle Stress Modulus: R 2  = 0.6037, P < .0001). Transesophageal echocardiography-derived stiffness moduli correlate strongly with aortic wall biomechanics and histopathology, which demonstrates the added benefit of using simple echocardiography-derived biomechanics to stratify patient populations. Copyright © 2018. Published by Elsevier Inc.

Juniper wood as a possible implant material.

PubMed

Gross, K A; Ezerietis, E

2003-03-15

Natural materials, such as wood and bone, possess structures fulfilling the requirements of support and transport of nutrients. Similarity in function and properties provides inspiration for investigating the possible use of wood as an implant material. Juniperus communis wood is dense, durable, and strong and has naturally impregnated essential oils that display antiseptic properties. This study investigated the toxicity of the oil, the effect of sterilization on the mechanical properties of the wood, and bone attachment with animal studies. The possible toxicity of the oil was determined orally and by intravenous injection. At low concentrations, the dose that would be released by the wood in the body could be tolerated without any detrimental effects. Sterilization of the wood in boiling water lowered the elastic modulus and modulus of rupture to a level at which the elastic modulus could be better matched to bone. Wood shaped into the form of femoral implants were implanted into rabbits and displayed good acceptance by the body up to a period of 3 years, indicating bone apposition, abutment into pores, and growth into drilled cavities. Copyright 2003 Wiley Periodicals, Inc.

Molecular weight dependency of polyrotaxane-cross-linked polymer gel extensibility.

PubMed

Ohmori, Kana; Abu Bin, Imran; Seki, Takahiro; Liu, Chang; Mayumi, Koichi; Ito, Kohzo; Takeoka, Yukikazu

2016-12-11

This work investigates the influence of the molecular weight of polyrotaxane (PR) cross-linkers on the extensibility of polymer gels. The polymer gels, which were prepared using PR cross-linkers of three different molecular weights but the same number of cross-linking points per unit volume of gel, have almost the same Young's modulus. By contrast, the extensibility and rupture strength of the polymer gels are substantially increased with increasing molecular weight of the PR cross-linker.

Passion fruit hulls particleboard: the effect of urea formaldehyde level on physical and mechanical properties

NASA Astrophysics Data System (ADS)

Iswanto, A. H.; Sucipto, T.; Adlina, E.; Prabuningrum, D. S.

2018-02-01

The purpose of this research was to explore the suitability of Passion Fruit Hulls (PFH) as a raw material particleboard with variants of urea formaldehyde adhesive content (UF). In this research, PFH particles filtered by sieve in size of 10 mesh to throw dust particles. Furthermore, the particles dried until reaches of 5% moisture content. Levels of UF adhesive was using comprise of 10%, 12% and 14%. Hot pressing conducted at 120°C temperature for 10 minutes at a pressure of 30 kg/cm2. The results showed that in moisture content for 10% adhesive level, almost all the parameters such as thickness swelling, modulus of elasticity (MOE) and modulus of rupture (MOR) that produced did not fulfiled the standard. The 14% adhesive level produced of the best of PFH particleboard.

Effect of Thermal Treatment of Fast Growing Wood Fibers on Physical and Mechanical Properties of Light Medium Density Fiberboard

NASA Astrophysics Data System (ADS)

Jarusombuti, Songklod; Ayrilmis, Nadir; Fueangvivat, Vallayuth; Bauchongkol, Piyawade

2011-06-01

This study investigated physical and mechanical properties of the light medium density fiberboard (MDF) panels made from thermally treated wood fibers of eucalyptus camaldulensis at three different temperatures (393 K, 423 K or 453 K) for 30 or 60 min in a laboratory autoclave. The average thickness swelling of the panels decreased by 16-54% depending on the treatment temperature and time. However, the modulus of rupture, modulus of elasticity, and internal bond strength decreased by 16-37%, 9-25% and 10-39%, respectively. Based on the findings obtained from the present study, it may be said that wood fibers of E. camaldulensis treated at 453 K - 30 min can be used in the light MDF manufacture for use in humid conditions, such as kitchen and bathroom furniture requiring improved dimensional stability.

Structural changes and rheological properties of dry abalone meat ( Haliotis diversicolor) during the process of water restoration

NASA Astrophysics Data System (ADS)

Gao, Xin; Zhang, Yaqi; Xu, Jiachao; Sun, Yan; Zhao, Qingxi; Chang, Yaoguang

2007-10-01

Changes in tissue structure, rheological property and water content of dry abalone meat in the process of water restoration were studied. The weight and volume of dry abalone meat increased with water restoration. When observed under a light microscope, structural change in myofibrils was obvious and a distinct network was found. When water restoration time increased from 24 h to 72 h, the instantaneous modulus E 0 and viscosity η 1 increased, whereas the rupture strength and relaxation time ( τ 1) were reduced. There were no significant changes of rheological parameters ( E 0, η 1, τ 1, rupture strength) from 72 h to 96 h of water restoration. Therefore, the dry abalone meat was swollen enough at the time of 72 h. The rheological parameters were obviously influenced by the structural changes.

Modules of rupture and oxidation resistance of S12.55Al0.6O0.72N3.52 sialon

NASA Technical Reports Server (NTRS)

Arias, A.

1979-01-01

A Sialon of formula Si2.55Al0.6O0.72N3.52 was made from ball-milled alpha-Si3N4, AIN, and SiO2 by sintering the powder compacts at 1760 C for 4 hours in stagnant nitrogen. This Sialon had an average modulus of rupture ranging from 404 megapascals (58.6 ksi) at room temperature to 254 megapascals (36.8 ksi) at 1400 C. Oxidation tests at 1400 C in air showed it to have a parabolic oxidation rate constant less than or equal to 2.8x10 to the -10th power sq g/cm4 hr, which is smaller than that of any other Si3N4-base ceramic reported in the literature.

LGM-30B, Stage II Dissected Motors Test Report,

DTIC Science & Technology

1980-07-01

Relaxation Test Data (Outer Propellant) 29 Table 9, Stress Relaxation Test Data (Inner Propellant) 31 Table 10 , Cohesive Tear Energy Test Data (Outer...Outer) 45 7 Maximum Stress (Inner) 46 8Strain at Rupture (Inner) 47 9 Modulus (Inner) 48 Regression Plot, Low Rate Tensile 10 Maximum Stress (Outer...outer propellants are almost the same. H. TEAR ENERGY TEST: Data from this test period are contained in Tables 10 and 11. Sufficient valid data became

Index to the Shock and Vibration Bulletins

DTIC Science & Technology

1968-02-01

125 modulus of elasticity vs tempera- ture for, 26-2-120 and nickel-chromium alloy, rupture life and creep rate, 26-2-288 Nike -Tomahawk missiles...measurement, 29-1-65 of missiles on wing of B-52, 28-1-187 of Nike -Zeus missiles, 31-1-21 prediction for large missiles, 28-4-28 on RB-66 and A3D...related to, 35-6-99 Charge weight vs crater radius, 32-2-38 Charpy tests of steel bars, 28-4-273 Chemical explosions nuclear detonation

Effect of Environment on Creep Behavior of an Oxide/Oxide CFCC with 45 deg. Fiber Orientation

DTIC Science & Technology

2006-06-01

MPa, the elastic modulus (E) was 45 GPa, and failure strain was 0.265%. The creep -rupture results showed a decrease in creep life with increasing...failure and increased creep life . A qualitative spectral analysis provided evidence of silicon species migration from the mullite phase of the...N720/AS in 0/90˚ and ±45˚ orientation at 1100°C. Shows that high creep rates generally correspond to a short creep life .................... 17

Hemp-Fiber-Reinforced Unsaturated Polyester Composites: Optimization of Processing and Improvement of Interfacial Adhesion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qui, Renhui; Ren, Xiaofeng; Fifield, Leonard S.

2011-02-25

The processing variables for making hemp-fiber-reinforced unsaturated polyester (UPE) composites were optimized through orthogonal experiments. It was found that the usage of initiator, methyl ethyl ketone peroxide, had the most significant effect on the tensile strength of the composites. The treatment of hemp fibers with a combination of 1, 6-diisocyanatohexane (DIH) and 2-hydroxylethyl acrylate (HEA) significantly increased tensile strength, flexural modulus of rupture and flexural modulus of elasticity, and water resistance of the resulting hemp-UPE composites. FTIR spectra revealed that DIH and HEA were covalently bonded to hemp fibers. Scanning electronic microscopy graphs of the fractured hemp-UPE composites demonstrated thatmore » treatment of hemp fibers with a combination of DIH and HEA greatly improved the interfacial adhesion between hemp fibers and UPE. The mechanism of improving the interfacial adhesion is proposed.« less

Effect of carbon fiber addition on the electromagnetic shielding properties of carbon fiber/polyacrylamide/wood based fiberboards

NASA Astrophysics Data System (ADS)

Dang, Baokang; Chen, Yipeng; Yang, Ning; Chen, Bo; Sun, Qingfeng

2018-05-01

Carbon fiber (CF) reinforced polyacrylamide/wood fiber composite boards are fabricated by mechanical grind-assisted hot-pressing, and are used for electromagnetic interference (EMI) shielding. CF with an average diameter of 150 nm is distributed on wood fiber, which is then encased by polyacrylamide. The CF/polyacrylamide/wood fiber (CPW) composite exhibits an optimal EMI shielding effectiveness (SE) of 41.03 dB compared to that of polyacrylamide/wood fiber composite (0.41 dB), which meets the requirements of commercial merchandise. Meanwhile, the CPW composite also shows high mechanical strength. The maximum modulus of rupture (MOR) and modulus of elasticity (MOE) of CPW composites are 39.52 MPa and 5823.15 MPa, respectively. The MOR and MOE of CPW composites increased by 38% and 96%, respectively, compared to that of polyacrylamide/wood fiber composite (28.64 and 2967.35 MPa).

Effect of carbon fiber addition on the electromagnetic shielding properties of carbon fiber/polyacrylamide/wood based fiberboards.

PubMed

Dang, Baokang; Chen, Yipeng; Yang, Ning; Chen, Bo; Sun, Qingfeng

2018-05-11

Carbon fiber (CF) reinforced polyacrylamide/wood fiber composite boards are fabricated by mechanical grind-assisted hot-pressing, and are used for electromagnetic interference (EMI) shielding. CF with an average diameter of 150 nm is distributed on wood fiber, which is then encased by polyacrylamide. The CF/polyacrylamide/wood fiber (CPW) composite exhibits an optimal EMI shielding effectiveness (SE) of 41.03 dB compared to that of polyacrylamide/wood fiber composite (0.41 dB), which meets the requirements of commercial merchandise. Meanwhile, the CPW composite also shows high mechanical strength. The maximum modulus of rupture (MOR) and modulus of elasticity (MOE) of CPW composites are 39.52 MPa and 5823.15 MPa, respectively. The MOR and MOE of CPW composites increased by 38% and 96%, respectively, compared to that of polyacrylamide/wood fiber composite (28.64 and 2967.35 MPa).

Physical properties of concrete made with Apollo 16 lunar soil sample

NASA Technical Reports Server (NTRS)

Lin, T. D.; Love, H.; Stark, D.

1992-01-01

This paper describes the first phase of the long-term investigation for the construction of concrete lunar bases. In this phase, petrographic and scanning electron microscope examinations showed that the morphology and elemental composition of the lunar soil made it suitable for use as a fine aggregate for concrete. Based on this finding, calcium aluminate cement and distilled water were mixed with the lunar soil to fabricate test specimens. The test specimens consisted of a 1-in cube, a 1/2-in cube, and three 0.12 x 0.58 x 3.15-in beam specimens. Tests were performed on these specimens to determine compressive strength, modulus of rupture, modulus of elasticity, and thermal coefficient of expansion. Based on examination of the material and test results, it is concluded that lunar soil can be used as a fine aggregate for concrete.

The Use of Mushroom Growing Media Waste for Making Composite Particle Board

NASA Astrophysics Data System (ADS)

Tjahjanti, P. H.; Sutarman; Widodo, E.; Kusuma, A. T.

2017-05-01

One of the agricultural waste is mushroom growing media, where the number of this waste is huge and accumulated after mushroom harvest. This accumulation is caused by using the new planting medias. Meanwhile, the old planting medias have thrown out and been as solid matter to widen the slope of cliff area. Therefore, this research aims to use mushroom growing media waste (MGMW) as a composite particle board added by polyester resin and mekpo (methyl ethyl ketone peroxides) as catalys. Some physical and mechanic tests which are done, namely: density, moisture content, thickness swelling after immersion in water, strength of absorption water, internal bonding, modulus of elasticity, modulus of rupture and screw holding power. The composition of 75% MGMW + 24% polyester resin + 1% catalyst mekpo suitable to the physical and mechanic tests and accordance with SNI 03-2105-2006 and JIS A 5908-2003.

Palaeo-adaptive properties of the xylem of Metasequoia: mechanical/hydraulic compromises.

PubMed

Jagels, Richard; Visscher, George E; Lucas, John; Goodell, Barry

2003-07-01

The xylem of Metasequoia glyptostroboides Hu et Cheng is characterized by very low density (average specific gravity = 0.27) and tracheids with relatively large dimensions (length and diameter). The microfibril angle in the S2 layer of tracheid walls is large, even in outer rings, suggesting a cambial response to compressive rather than tensile stresses. In some cases, this compressive stress is converted to irreversible strain (plastic deformation), as evidenced by cell wall corrugations. The heartwood is moderately decay resistant, helping to prevent Brazier buckling. These xylem properties are referenced to the measured bending properties of modulus of rupture and modulus of elasticity, and compared with other low-to-moderate density conifers. The design strategy for Metasequoia is to produce a mechanically weak but hydraulically efficient xylem that permits rapid height growth and crown development to capture and dominate a wet site environment. The adaptability of these features to a high-latitude Eocene palaeoenvironment is discussed.

Effect of Atmospheric Corrosion on the Mechanical Properties of SAE 1020 Structural Steel.

PubMed

Martínez, Carola; Briones, Francisco; Villarroel, María; Vera, Rosa

2018-04-11

Resistance to atmospheric corrosion in different environments located in Chile and the corrosion's effect on the mechanical properties of SAE 1020 steel were studied. Atmospheric corrosivity categories at each station under study were determined. These categories were C2, for Laja; C3 and C4, for the Arica and Antarctic stations, respectively; and the most aggressive, C5 and higher at Quintero. These specific environments significantly influenced the mechanical responses of steel exposed for 36 months. Rupture elongation, the modulus of toughness, ultimate tensile strength, and hardness of the material all decreased as a function of environmental atmospheric aggressiveness. Lowered ductility is the result of the increased corrosion rate due to the high deposition of chlorides. This is due to the morphology of material degradation, which consequently occurs as pores, microstrains, and other defects that promote early rupture of the steel.

Effect of Atmospheric Corrosion on the Mechanical Properties of SAE 1020 Structural Steel

PubMed Central

Briones, Francisco; Villarroel, María; Vera, Rosa

2018-01-01

Resistance to atmospheric corrosion in different environments located in Chile and the corrosion’s effect on the mechanical properties of SAE 1020 steel were studied. Atmospheric corrosivity categories at each station under study were determined. These categories were C2, for Laja; C3 and C4, for the Arica and Antarctic stations, respectively; and the most aggressive, C5 and higher at Quintero. These specific environments significantly influenced the mechanical responses of steel exposed for 36 months. Rupture elongation, the modulus of toughness, ultimate tensile strength, and hardness of the material all decreased as a function of environmental atmospheric aggressiveness. Lowered ductility is the result of the increased corrosion rate due to the high deposition of chlorides. This is due to the morphology of material degradation, which consequently occurs as pores, microstrains, and other defects that promote early rupture of the steel. PMID:29641490

Based on records of Three Gorge Telemetric Seismic Network to analyze Vibration process of micro fracture of rock landslide

NASA Astrophysics Data System (ADS)

WANG, Q.

2017-12-01

Used the finite element analysis software GeoStudio to establish vibration analysis model of Qianjiangping landslide, which locates at the Three Gorges Reservoir area. In QUAKE/W module, we chosen proper Dynamic elasticity modulus and Poisson's ratio of soil layer and rock stratum. When loading, we selected the waveform data record of Three Gorge Telemetric Seismic Network as input ground motion, which includes five rupture events recorded of Lujiashan seismic station. In dynamic simulating, we mainly focused on sliding process when the earthquake date record was applied. The simulation result shows that Qianjiangping landslide wasn't not only affected by its own static force, but also experienced the dynamic process of micro fracture-creep-slip rupture-creep-slip.it provides a new approach for the early warning feasibility of rock landslide in future research.

FROM ACUTE ACHILLES TENDON RUPTURE TO RETURN TO PLAY - A CASE REPORT EVALUATING RECOVERY OF TENDON STRUCTURE, MECHANICAL PROPERTIES, CLINICAL AND FUNCTIONAL OUTCOMES.

PubMed

Zellers, Jennifer A; Cortes, Daniel H; Silbernagel, Karin Grävare

2016-12-01

Achilles tendon rupture results in significant functional deficits regardless of treatment strategy (surgical versus non-surgical intervention). Recovery post-rupture is highly variable, making comprehensive patient assessment critical. Assessment tools may change along the course of recovery as the patient progresses - for instance, moving from a seated heel-rise to standing heel-rise to jump testing. However, tools that serve as biomarkers for early recovery may be particularly useful in informing clinical decision-making. The purpose of this case report was to describe the progress of a young, athletic individual following Achilles tendon rupture managed non-surgically, using patient reported and functional performance outcome measures and comprehensively evaluating Achilles tendon structure and function incorporating a novel imaging technique (cSWE). The subject is a 26 year-old, female basketball coach who sustained an Achilles tendon rupture and was managed non-surgically. The subject was able to steadily progress using a gradual tendon loading treatment approach well-supported by the literature. Multiple evaluative techniques including the addition of diagnostic ultrasound imaging and continuous shear wave elastography (cSWE) to standard clinical tests and measures were used to assess patient-reported symptoms, tendon structure, and tendon functional performance. Five assessments were performed over the course of 2-14 months post-rupture. By the 14-month follow-up, the subject had achieved full self-reported function. Tendon structural and mechanical properties showed similar shear modulus by 14 months, however, viscosity continued to be lower and tendon length longer on the ruptured side. Functional performance, evidenced by the heel-rise test and jump tests, also showed a positive trajectory, however, deficits of 12-28% remained between ruptured and non-ruptured sides at 14 months. This case report outlines comprehensive outcomes assessment in an athletic individual following non-surgically managed Achilles tendon rupture using a wide variety of tools that capture different aspects of tendon health. Interestingly, the course of recovery of patient symptoms, functional performance, and tendon structure do not occur in the same time frame. Therefore, it is important to assess patient outcomes using multiple outcome measures encompassing different aspects of patient performance to ensure the patient is progressing steadily with rehabilitation. Level 4.

Exposure to Bordetella pertussis adenylate cyclase toxin affects integrin-mediated adhesion and mechanics in alveolar epithelial cells.

PubMed

Angely, Christelle; Nguyen, Ngoc-Minh; Andre Dias, Sofia; Planus, Emmanuelle; Pelle, Gabriel; Louis, Bruno; Filoche, Marcel; Chenal, Alexandre; Ladant, Daniel; Isabey, Daniel

2017-08-01

The adenylate cyclase (CyaA) toxin is a major virulent factor of Bordetella pertussis, the causative agent of whooping cough. CyaA toxin is able to invade eukaryotic cells where it produces high levels of cyclic adenosine monophosphate (cAMP) affecting cellular physiology. Whether CyaA toxin can modulate cell matrix adhesion and mechanics of infected cells remains largely unknown. In this study, we use a recently proposed multiple bond force spectroscopy (MFS) with an atomic force microscope to assess the early phase of cell adhesion (maximal detachment and local rupture forces) and cell rigidity (Young's modulus) in alveolar epithelial cells (A549) for toxin exposure <1 h. At 30 min of exposure, CyaA toxin has a minimal effect on cell viability (>95%) at CyaA concentration of 0.5 nM, but a significant effect (≈81%) at 10 nM. MFS performed on A549 for three different concentrations (0.5, 5 and 10 nM) demonstrates that CyaA toxin significantly affects both cell adhesion (detachment forces are decreased) and cell mechanics (Young's modulus is increased). CyaA toxin (at 0.5 nM) assessed at three indentation/retraction speeds (2, 5 and 10 μm/s) significantly affects global detachment forces, local rupture events and Young modulus compared with control conditions, while an enzymatically inactive variant CyaAE5 has no effect. These results reveal the loading rate dependence of the multiple bonds newly formed between the cell and integrin-specific coated probe as well as the individual bond kinetics which are only slightly affected by the patho-physiological dose of CyaA toxin. Finally, theory of multiple bond force rupture enables us to deduce the bond number N which is reduced by a factor of 2 upon CyaA exposure (N ≈ 6 versus N ≈ 12 in control conditions). MFS measurements demonstrate that adhesion and mechanical properties of A549 are deeply affected by exposure to the CyaA toxin but not to an enzymatically inactive variant. This indicates that the alteration of cell mechanics triggered by CyaA is a consequence of the increase in intracellular cAMP in these target cells. These results suggest that mechanical and adhesion properties of the cells appear as pertinent markers of cytotoxicity of CyaA toxin. © 2017 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

Application of scanning acoustic microscopy to advanced structural ceramics

NASA Technical Reports Server (NTRS)

Vary, Alex; Klima, Stanley J.

1987-01-01

A review is presentod of research investigations of several acoustic microscopy techniques for application to structural ceramics for advanced heat engines. Results obtained with scanning acoustic microscopy (SAM), scanning laser acoustic microscopy (SLAM), scanning electron acoustic microscopy (SEAM), and photoacoustic microscopy (PAM) are compared. The techniques were evaluated on research samples of green and sintered monolithic silicon nitrides and silicon carbides in the form of modulus-of-rupture bars containing deliberately introduced flaws. Strengths and limitations of the techniques are described with emphasis on statistics of detectability of flaws that constitute potential fracture origins.

Method and apparatus for determining tensile strength

DOEpatents

Ratigan, J.L.

1982-05-28

A method and apparatus is described for determining the statistical distribution of apparent tensile strength of rock, the size effect with respect to tensile strength, as well as apparent deformation modulus of both intact and fractured or jointed rock. The method is carried out by inserting a plug of deformable material, such as rubber, in an opening of a specimen to be tested. The deformable material is loaded by an upper and lower platen until the specimen ruptures, whereafter the tensile strength is calculated based on the parameters of the test specimen and apparatus.

Method and apparatus for determining tensile strength

DOEpatents

Ratigan, Joe L.

1984-01-01

A method and apparatus for determining the statistical distribution of apparent tensile strength of rock, the size effect with respect to tensile strength, as well as apparent deformation modulus of both intact and fractured or jointed rock. The method is carried out by inserting a plug of deformable material, such as rubber, in an opening of a specimen to be tested. The deformable material is loaded by an upper and lower platen until the specimen ruptures, whereafter the tensile strength is calculated based on the parameters of the test specimen and apparatus.

Pulsatile blood flow in elastic artery with model aneurysm

NASA Astrophysics Data System (ADS)

Nikolov, N.; Radev, St.; Tabakova, S.

2017-11-01

The mathematical modeling and numerical simulations are expected to play an important role to predict the genesis of different cardiovascular diseases, such as the formation and rupture of aneurysms. In the present work, the numerical solutions of the oscillatory blood flow are constructed for an elastic artery with a model aneurysm by use of the software ANSYS. It is observed that the artery elastic strain behaves in a different way: stably or unstably depending on the different combinations between the flow parameter (outlet pressure) and the elastic modulus of the artery wall.

Brittle Materials Design, High Temperature Gas Turbine

DTIC Science & Technology

1976-10-01

f7<psBCsqRf°?^PM^ppRi^Sq^PMip««niS! V Modulus of Rupture tests were conducted on 274 specimens of hot pressed silicon nitride to investigate the...Reaction Sintered 813^ 4. 3 Nitriding Developments 4.4 Sialon Materials 4. 5 Silicon Milling Studies 5. References v Page No. 1 ii...iv v vi ix 1 3 5 7 7 14 17 19 19 21 38 48 65 66 73 75 87 89 97 101 103 .:,:.o:^ -.. ...•• ._ . .- —~ «-«aa. m

The simulation of magnetic resonance elastography through atherosclerosis.

PubMed

Thomas-Seale, L E J; Hollis, L; Klatt, D; Sack, I; Roberts, N; Pankaj, P; Hoskins, P R

2016-06-14

The clinical diagnosis of atherosclerosis via the measurement of stenosis size is widely acknowledged as an imperfect criterion. The vulnerability of an atherosclerotic plaque to rupture is associated with its mechanical properties. The potential to image these mechanical properties using magnetic resonance elastography (MRE) was investigated through synthetic datasets. An image of the steady state wave propagation, equivalent to the first harmonic, can be extracted directly from finite element analysis. Inversion of this displacement data yields a map of the shear modulus, known as an elastogram. The variation of plaque composition, stenosis size, Gaussian noise, filter thresholds and excitation frequency were explored. A decreasing mean shear modulus with an increasing lipid composition was identified through all stenosis sizes. However the inversion algorithm showed sensitivity to parameter variation leading to artefacts which disrupted both the elastograms and quantitative trends. As noise was increased up to a realistic level, the contrast was maintained between the fully fibrous and lipid plaques but lost between the interim compositions. Although incorporating a Butterworth filter improved the performance of the algorithm, restrictive filter thresholds resulted in a reduction of the sensitivity of the algorithm to composition and noise variation. Increasing the excitation frequency improved the techniques ability to image the magnitude of the shear modulus and identify a contrast between compositions. In conclusion, whilst the technique has the potential to image the shear modulus of atherosclerotic plaques, future research will require the integration of a heterogeneous inversion algorithm. Copyright © 2016 Elsevier Ltd. All rights reserved.

Statistical relations among earthquake magnitude, surface rupture length, and surface fault displacement

USGS Publications Warehouse

Bonilla, M.G.; Mark, R.K.; Lienkaemper, J.J.

1984-01-01

In order to refine correlations of surface-wave magnitude, fault rupture length at the ground surface, and fault displacement at the surface by including the uncertainties in these variables, the existing data were critically reviewed and a new data base was compiled. Earthquake magnitudes were redetermined as necessary to make them as consistent as possible with the Gutenberg methods and results, which necessarily make up much of the data base. Measurement errors were estimated for the three variables for 58 moderate to large shallow-focus earthquakes. Regression analyses were then made utilizing the estimated measurement errors. The regression analysis demonstrates that the relations among the variables magnitude, length, and displacement are stochastic in nature. The stochastic variance, introduced in part by incomplete surface expression of seismogenic faulting, variation in shear modulus, and regional factors, dominates the estimated measurement errors. Thus, it is appropriate to use ordinary least squares for the regression models, rather than regression models based upon an underlying deterministic relation with the variance resulting from measurement errors. Significant differences exist in correlations of certain combinations of length, displacement, and magnitude when events are qrouped by fault type or by region, including attenuation regions delineated by Evernden and others. Subdivision of the data results in too few data for some fault types and regions, and for these only regressions using all of the data as a group are reported. Estimates of the magnitude and the standard deviation of the magnitude of a prehistoric or future earthquake associated with a fault can be made by correlating M with the logarithms of rupture length, fault displacement, or the product of length and displacement. Fault rupture area could be reliably estimated for about 20 of the events in the data set. Regression of MS on rupture area did not result in a marked improvement over regressions that did not involve rupture area. Because no subduction-zone earthquakes are included in this study, the reported results do not apply to such zones.

Statistical relations among earthquake magnitude, surface rupture length, and surface fault displacement

USGS Publications Warehouse

Bonilla, Manuel G.; Mark, Robert K.; Lienkaemper, James J.

1984-01-01

In order to refine correlations of surface-wave magnitude, fault rupture length at the ground surface, and fault displacement at the surface by including the uncertainties in these variables, the existing data were critically reviewed and a new data base was compiled. Earthquake magnitudes were redetermined as necessary to make them as consistent as possible with the Gutenberg methods and results, which make up much of the data base. Measurement errors were estimated for the three variables for 58 moderate to large shallow-focus earthquakes. Regression analyses were then made utilizing the estimated measurement errors.The regression analysis demonstrates that the relations among the variables magnitude, length, and displacement are stochastic in nature. The stochastic variance, introduced in part by incomplete surface expression of seismogenic faulting, variation in shear modulus, and regional factors, dominates the estimated measurement errors. Thus, it is appropriate to use ordinary least squares for the regression models, rather than regression models based upon an underlying deterministic relation in which the variance results primarily from measurement errors.Significant differences exist in correlations of certain combinations of length, displacement, and magnitude when events are grouped by fault type or by region, including attenuation regions delineated by Evernden and others.Estimates of the magnitude and the standard deviation of the magnitude of a prehistoric or future earthquake associated with a fault can be made by correlating Ms with the logarithms of rupture length, fault displacement, or the product of length and displacement.Fault rupture area could be reliably estimated for about 20 of the events in the data set. Regression of Ms on rupture area did not result in a marked improvement over regressions that did not involve rupture area. Because no subduction-zone earthquakes are included in this study, the reported results do not apply to such zones.

Effects of Surface Treatments on Mechanical Properties and Water Resistance of Kenaf Fiber-Reinforced Unsaturated Polyester Composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Xiaofeng; Qui, Renhui; Fifield, Leonard S.

2012-05-17

Effects of surface treatments on the strength and water resistance of kenaf fiber-reinforced unsaturated polyester (UPE) composites were investigated. A new coupling agent that consists of 1,6-diisocyanato-hexane (DIH) and 2-hydroxylethyl acrylate (HEA) was investigated for surface treatments of kenaf fibers. The surface treatments were found to significantly enhance the tensile strength, modulus of rupture, modulus of elasticity, and water resistance of the resulting kenaf UPE composites. Fourier transform infrared spectroscopy (FTIR) confirmed that DIH-HEA was covalently bonded onto kenaf fibers. Scanning electron microscopy (SEM) images of the composites revealed that chemical treatment of kenaf fibers with a combination of DIHmore » and HEA improved the interfacial adhesion between kenaf fibers and UPE resin in the DIHHEA-treated kenafUPE composites. The mechanisms by which the chemical treatment of kenaf fiber surfaces improved strength and water resistance of the resulting kenaf UPE composites were discussed.« less

Speaker box made of composite particle board based on mushroom growing media waste

NASA Astrophysics Data System (ADS)

Tjahjanti, P. H.; Sutarman, Widodo, E.; Kurniawan, A. R.; Winarno, A. T.; Yani, A.

2017-06-01

This research aimed to use mushroom growing media waste (MGMW) that was added by urea, starch and polyvinyl chloride (PVC) glue as a composite particle board to be used as the material of speaker box manufacture. Physical and mechanical testing of particle board including density, moisture content, thickness swelling after immersion in water, strength in water absorption, internal bonding, modulus of elasticity, modulus of rupture and screw holding power, were carried out in accordance with the Stándar Nasional Indonesia (SNI) 03-2105-2006 and Japanese International Standard (JIS) A 5908-2003. The optimum composition of composite particle boards was 60% MGMW + 39% (50% urea +50% starch) + 1% PVC glue. Furthermore, the optimum composition to create speaker box with hardness values of 14.9 Brinnel Hardness Number and results of vibration test obtained amplitude values of the Z-axis, minimum of 0.032007 and maximum of 0.151575. For the acoustic test, results showed good sound absorption coefficients at frequencies of 500 Hz and it has better damping absorption.

Palaeo‐adaptive Properties of the Xylem of Metasequoia: Mechanical/Hydraulic Compromises

PubMed Central

JAGELS, RICHARD; VISSCHER, GEORGE E.; LUCAS, JOHN; GOODELL, BARRY

2003-01-01

The xylem of Metasequoia glyptostroboides Hu et Cheng is characterized by very low density (average specific gravity = 0·27) and tracheids with relatively large dimensions (length and diameter). The microfibril angle in the S2 layer of tracheid walls is large, even in outer rings, suggesting a cambial response to compressive rather than tensile stresses. In some cases, this compressive stress is converted to irreversible strain (plastic deformation), as evidenced by cell wall corrugations. The heartwood is moderately decay resistant, helping to prevent Brazier buckling. These xylem properties are referenced to the measured bending properties of modulus of rupture and modulus of elasticity, and compared with other low‐to‐moderate density conifers. The design strategy for Metasequoia is to produce a mechanically weak but hydraulically efficient xylem that permits rapid height growth and crown development to capture and dominate a wet site environment. The adaptability of these features to a high‐latitude Eocene palaeoenvironment is discussed. PMID:12763758

Mechanical deterioration underlies malignant behavior of aneurysmal human ascending aorta.

PubMed

Koullias, George; Modak, Raj; Tranquilli, Maryann; Korkolis, Dimitris P; Barash, Paul; Elefteriades, John A

2005-09-01

The human ascending aorta becomes markedly prone to rupture and dissection at a diameter of 6 cm. The mechanical substrate for this malignant behavior is unknown. This investigation applied engineering analysis to human ascending aortic aneurysms and compared their structural characteristics with those of normal aortas. We measured the mechanical characteristics of the aorta by direct epiaortic echocardiography at the time of surgery in 33 patients with ascending aortic aneurysm undergoing aortic replacement and in 20 control patients with normal aortas undergoing coronary artery bypass grafting. Six parameters were measured in all patients: aortic diameter in systole and diastole, aortic wall thickness in systole and diastole, and blood pressure in systole and diastole. These were used to calculate mechanical characteristics of the aorta from standard equations. Aortic distensibility reflects the elastic qualities of the aorta. Aortic wall stress reflects the disrupting force experienced within the aortic wall. Incremental elastic modulus indicates loss of elasticity reserve. Aortic distensibility falls to extremely low levels as aortic dimension rises toward 6 cm (3.02 mm Hg(-1) for small aortas versus 1.45 mm Hg(-1) for aortas larger than 5 cm, P < .05). Aortic wall stress rises to 157.8 kPa for the aneurysmal aorta, compared with 92.5 kPa for normal aortas. For 6-cm aortas at pressures of 200 mm Hg or more, wall stress rises to 857 kPa, nearly exceeding the known maximal tensile strength of human aneurysmal aortic wall. Incremental elastic modulus deteriorates (1.93 +/- 0.88 MPa vs 1.18 +/- 0.21 MPa, P < .05) in aneurysmal aortas relative to that in normal aortas. The mechanical properties of the aneurysmal aorta deteriorate dramatically as the aorta enlarges, reaching critical levels associated with rupture by a diameter of 6 cm. This mechanical deterioration provides an explanation in engineering terms for the malignant clinical behavior (rupture and dissection) of the aorta at these dimensions. This work adds to our fundamental understanding of the biology of aortic aneurysms and promises to permit future application of engineering measurements to supplement aneurysm size in clinical decision making in aneurysmal disease.

Preliminary Investigation of the Effect of Surface Treatment on the Strength of a Titanium Carbide - 30 Percent Nickel Base Cermet

NASA Technical Reports Server (NTRS)

Robins, Leonard; Grala, Edward M

1957-01-01

Specimens of a nickel-bonded titanium carbide cermet were given the following surface treatments: (1) grinding, (2) lapping, (3) blast cleaning, (4) acid roughening, (5) oxidizing, and (6) oxidizing and refinishing. Room-temperature modulus-of-rupture and impact strength varied with the different surface treatments. Considerable strength losses resulted from the following treatments: (1) oxidation at 1600 F for 100 hours, (2) acid roughening, and (3) severe grinding with 60-grit silicon carbide abrasive. The strength loss after oxidation was partially recovered by grit blasting or diamond grinding.

Dissipative particle dynamics simulations of polymersomes.

PubMed

Ortiz, Vanessa; Nielsen, Steven O; Discher, Dennis E; Klein, Michael L; Lipowsky, Reinhard; Shillcock, Julian

2005-09-22

A DPD model of PEO-based block copolymer vesicles in water is developed by introducing a new density based coarse graining and by using experimental data for interfacial tension. Simulated as a membrane patch, the DPD model is in excellent agreement with experimental data for both the area expansion modulus and the scaling of hydrophobic core thickness with molecular weight. Rupture simulations of polymer vesicles, or "polymersomes", are presented to illustrate the system sizes feasible with DPD. The results should provide guidance for theoretical derivations of scaling laws and also illustrate how spherical polymer vesicles might be studied in simulation.

Tensile properties of orthodontic elastomeric ligatures.

PubMed

Ahrari, F; Jalaly, T; Zebarjad, M

2010-01-01

Tensile properties of elastomeric ligatures become important when efficiency of orthodontic appliances is considered. The aim of this study was to compare tensile strength, extension to tensile strength, toughness and modulus of elasticity of elastomeric ligatures in both the as--received condition and after 28 days of immersion in the simulated oral environment. Furthermore, the changes that occurred in tensile properties of each brand of ligatures after 28 days were evaluated. Experimental-laboratory based. Elastomeric ligatures were obtained from different companies and their tensile properties were measured using Zwick testing machine in both the as-received condition and after 28 days of immersion in the simulated oral environment. The data were analyzed using independent sample t-tests, analysis of variance and Tukey tests. After 28 days, all the ligatures experienced a significant decrease in tensile strength, extension to tensile strength and toughness ( P < 0.05), whereas modulus of elasticity increased in some groups and decreased in others. There were significant differences in tensile properties of different brands of ligatures in both conditions ( P < 0.05), with the exception of modulus of elasticity after 28 days. The decrease in strength properties of elastomeric ligatures shows that they should be replaced at each appointment to reduce the risk of rupture. There are significant differences in tensile properties of different brands of ligatures, which should be considered during selection of these products.

Formation and rupture of Ca(2+) induced pectin biopolymer gels.

PubMed

Basak, Rajib; Bandyopadhyay, Ranjini

2014-10-07

When calcium salts are added to an aqueous solution of polysaccharide pectin, ionic cross-links form between pectin chains, giving rise to a gel network in dilute solution. In this work, dynamic light scattering (DLS) is employed to study the microscopic dynamics of the fractal aggregates (flocs) that constitute the gels, while rheological measurements are carried out to study the process of gel rupture. As the calcium salt concentration is increased, DLS experiments reveal that the polydispersity of the flocs increase simultaneously with the characteristic relaxation times of the gel network. Above a critical salt concentration, the flocs become interlinked to form a reaction-limited fractal gel network. Rheological studies demonstrate that the limits of the linear rheological response and the critical stresses required to rupture these networks both decrease with the increase in salt concentration. These features indicate that the ion-mediated pectin gels studied here lie in a 'strong link' regime that is characterised by inter-floc links that are stronger than intra-floc links. A scaling analysis of the experimental data presented here demonstrates that the elasticities of the individual fractal flocs exhibit power-law dependences on the added salt concentration. We conclude that when both pectin and salt concentrations are increased, the number of fractal flocs of pectin increases simultaneously with the density of crosslinks, giving rise to very large values of the bulk elastic modulus.

Horizontal surface-slip distribution through several seismic cycles: The Eastern Bogd fault, Gobi-Altai, Mongolia

NASA Astrophysics Data System (ADS)

Kurtz, R.; Klinger, Y.; Ferry, M.; Ritz, J.-F.

2018-06-01

The 1957, MW 8.1, Gobi-Altai earthquake, Southern Mongolia, produced a 360-km-long surface rupture along the Eastern Bogd fault. Cumulative offsets of geomorphic features suggest that the Eastern Bogd fault might produce characteristic slip over the last seismic cycles. Using orthophotographs derived from a dataset of historical aerial photographs acquired in 1958, we measured horizontal offsets along two thirds ( 170 km) of the 1957 left-lateral strike-slip surface rupture. We propose a new empirical methodology to extract the average slip for each past earthquake that could be recognized along successive fault segments, to determine the slip distribution associated with successive past earthquakes. Our results suggest that the horizontal slip distribution of the 1957 Gobi-Altai earthquake is fairly flat, with an average offset of 3.5 m ± 1.3 m. A combination of our lateral measurements with vertical displacements derived from the literature, allows us to re-assess the magnitude of the Gobi-Altai earthquake to be between MW 7.8 and MW 8.2, depending on the depth of the rupture, and related value of the shear modulus. When comparing this magnitude to magnitudes derived from seismic data, it suggests that the rupture may have extended deeper than the 15 km to 20 km usually considered for the seismogenic crust. We observe that some fault segments are more likely than others to record seismic deformation through several seismic cycles, depending on the local rupture complexity and geomorphology. Additionally, our results allow us to model the horizontal slip function for the 1957 Gobi-Altai earthquake and for three previous paleoseismic events along 70% of the studied area. Along about 50% of the fault sections where we could recognize three past earthquakes, our results suggest that the slip per event was similar for each earthquake.

Elongational rheology and cohesive fracture of photo-oxidated LDPE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rolón-Garrido, Víctor H., E-mail: victor.h.rolongarrido@tu-berlin.de; Wagner, Manfred H.

2014-01-15

It was found recently that low-density polyethylene (LDPE) samples with different degrees of photo-oxidation represent an interesting system to study the transition from ductile to cohesive fracture and the aspects of the cohesive rupture in elongational flow. Sheets of LDPE were subjected to photo-oxidation in the presence of air using a xenon lamp to irradiate the samples for times between 1 day and 6 weeks. Characterisation methods included Fourier transform infrared spectroscopy, solvent extraction method, and rheology in shear and uniaxial extensional flows. Linear viscoelasticity was increasingly affected by increasing photo-oxidation due to crosslinking of LDPE, as corroborated by themore » carbonyl index, acid and aldehydes groups, and gel fraction. The molecular stress function model was used to quantify the experimental data, and the nonlinear model parameter β was found to be correlated with the gel content. The uniaxial data showed that the transition from ductile to cohesive fracture was shifted to lower elongational rates, the higher the gel content was. From 2 weeks photo-oxidation onwards, cohesive rupture occurred at every strain rate investigated. The true strain and true stress at cohesive fracture as well as the energy density applied to the sample up to fracture were analyzed. At low gel content, rupture was mainly determined by the melt fraction while at high gel content, rupture occurred predominantly in the gel structure. The strain at break was found to be independent of strain rate, contrary to the stress at break and the energy density. Thus, the true strain and not the stress at break or the energy density was found to be the relevant physical quantity to describe cohesive fracture behavior of photo-oxidated LDPE. The equilibrium modulus of the gel structures was correlated with the true strain at rupture. The stiffer the gel structure, the lower was the deformation tolerated before the sample breaks.« less

The effect of particle immersing in acetic acid solution on dimensional stability and strength properties of particleboard

NASA Astrophysics Data System (ADS)

Heri Iswanto, Apri; Hermanto, Samuel; Sucipto, Tito

2018-03-01

The objective of the research was to evaluate the effect of particle immersing treatments in acetic acid (AA) solution on dimensional stability and strength properties of particleboard. Particle was immersed in various level AA solution namely 0 (untreated), 1, 2, 3, 4% for 24 hours. Afterward, the particle was oven dried up to 5% moisture content. The amount of 12% UF resin level used for binding in manufacturing particleboard. Board size, thickness and density target in this experiment was 25 by 25 cm2, 1 cm, and 0.75 g/cm3 respectively. After mat forming, board pressed using 130°C temperature, 30 kg/cm2, and pressure for 10 minutes. The results showed that particles immersing in AA solution provide enhancement of thickness swelling (TS) parameters. Overall, 1% AA solution is the best treatment to improve dimensional stability. The similar results also showed by internal bond value. In general, the excess of 1% acetic acid level resulted in decreasing of IB value. A similar trend also occurs in modulus of rupture (MoR) and modulus of elasticity (MoE) parameters.

Intercalated Nanocomposites Based on High-Temperature Superconducting Ceramics and Their Properties

PubMed Central

Tonoyan, Anahit; Schiсk, Christoph; Davtyan, Sevan

2009-01-01

High temperature superconducting (SC) nanocomposites based on SC ceramics and various polymeric binders were prepared. Regardless of the size of the ceramics’ grains, the increase of their amount leads to an increase of resistance to rupture and modulus and a decrease in limiting deformation, whereas an increase in the average ceramic grain size worsens resistance properties. The SC, thermo-chemical, mechanical and dynamic-mechanical properties of the samples were investigated. Superconducting properties of the polymer ceramic nanocomposites are explained by intercalation of macromolecule fragments into the interstitial layer of the ceramics’ grains. This phenomenon leads to a change in the morphological structure of the superconducting nanocomposites.

Evaluation of Alternative Refractory Materials for the Main Flame Deflectors at KSC Launch Complexes

NASA Technical Reports Server (NTRS)

Calle, Luz Marina; Trejo, David; Rutkowsky, Justin

2006-01-01

The deterioration of the refractory materials used to protect the KSC launch complex steel base structures from the high temperatures during launches results in frequent and costly repairs and safety hazards. KSC-SPEC-P-0012, Specification for Refractory Concrete, is ineffective in qualifying refractory materials. This study of the specification and of alternative refractory materials recommends a complete revision of the specification and further investigation of materials that were found to withstand the environment of the Solid Rocket Booster main flame deflector better than the refractory materials in current use in terms of compressive strength, tensile strength, modulus of rupture, shrinkage, and abrasion.

Elastic energy distribution in bi-material lithosphere: implications for shear zone formation

NASA Astrophysics Data System (ADS)

So, B.; Yuen, D. A.

2013-12-01

Shear instability in the lithosphere can cause mechanical rupturing such as slab detachment and deep focus earthquake. Recent studies reported that bi-material interface, which refers to sharp elastic modulus contrast, plays an important role in triggering the instability [So and Yuen et al., 2012, GJI]. In present study, we performed two-dimensional numerical simulations to investigate the distribution of thermal-mechanical energy within the bi-material lithosphere. Under the far-field constant compression exerted on the domain, a larger elastic energy is accumulated into the compliant part than stiff medium. For instance, the compliant part has two times greater elastic energy density than surrounding stiff part, when the elastic modulus contrast between two different parts is five. Although these elastic energies in both parts are conversed into thermal energies after plastic yielding, denser elastic energy in the compliant is released more efficiently. This leads to efficient strength weakening and the subsequent ductile shear zone in the compliant part. We propose that strong shear heating occurs in lithosphere with the bi-material interface due to locally non-uniform distribution of the energy around the interface.

Properties of PZT-Based Piezoelectric Ceramics Between -150 and 250 C

NASA Technical Reports Server (NTRS)

Hooker, Matthew W.

1998-01-01

The properties of three PZT-based piezoelectric ceramics and one PLZT electrostrictive ceramic were measured as a function of temperature. In this work, the dielectric, ferroelectric polarization versus electric field, and piezoelectric properties of PZT-4, PZT-5A, PZT-5H, and PLZT-9/65/35 were measured over a temperature range of -150 to 250 C. In addition to these measurements, the relative thermal expansion of each composition was measured from 25 to 600 C and the modulus of rupture of each material was measured at room temperature. This report describes the experimental results and compares and contrasts the properties of these materials with respect to their applicability to intelligent aerospace systems.

Characterization of the mechanical and physical properties of TD-NiCr (Ni-20Cr-2ThO2) alloy sheet

NASA Technical Reports Server (NTRS)

Fritz, L. J.; Koster, W. P.; Taylor, R. E.

1973-01-01

Sheets of TD-NiCr processed using techniques developed to produce uniform material were tested to supply mechanical and physical property data. Two heats each of 0.025 and 0.051 cm thick sheet were tested. Mechanical properties evaluated included tensile, modulus of elasticity, Poisson's Ratio, compression, creep-rupture, creep strength, bearing strength, shear strength, sharp notch and fatigue strength. Test temperatures covered the range from ambient to 1589K. Physical properties were also studied as a function of temperature. The physical properties measured were thermal conductivity, linear thermal expansion, specific heat, total hemispherical emittance, thermal diffusivity, and electrical conductivity.

Elevated Temperature Properties of Titanium Carbide Base Ceramals Containing Nickel or Iron

NASA Technical Reports Server (NTRS)

Cooper, A L; Colteryahn, L E

1951-01-01

Elevated-temperature properties of titanium carbide base ceramals containing nickel or iron were determined in oxidation, modulus of rupture, tensile strength, and thermal-shock resistance. These materials followed the general growth law and exhibited two stages in oxidation. The following tensile strengths were found at 2000 degrees F: 13.3 weight percent nickel, 16, 150 pounds per square inch; 11.8 weight percent iron, 12,500 pounds per square inch; unalloyed titanium carbide, 16,450 pounds per square inch. Nickel or iron additions to titanium carbide improved the thermal-shock resistance, nickel more. The path of fracture in tensile and thermal-shock specimens was found to progress approximately 50 percent intergranularly and 50 percent transgranularly.

Rupture Speed and Dynamic Frictional Processes for the 1995 ML4.1 Shacheng, Hebei, China, Earthquake Sequence

NASA Astrophysics Data System (ADS)

Liu, B.; Shi, B.

2010-12-01

An earthquake with ML4.1 occurred at Shacheng, Hebei, China, on July 20, 1995, followed by 28 aftershocks with 0.9≤ML≤4.0 (Chen et al, 2005). According to ZÚÑIGA (1993), for the 1995 ML4.1 Shacheng earthquake sequence, the main shock is corresponding to undershoot, while aftershocks should match overshoot. With the suggestion that the dynamic rupture processes of the overshoot aftershocks could be related to the crack (sub-fault) extension inside the main fault. After main shock, the local stresses concentration inside the fault may play a dominant role in sustain the crack extending. Therefore, the main energy dissipation mechanism should be the aftershocks fracturing process associated with the crack extending. We derived minimum radiation energy criterion (MREC) following variational principle (Kanamori and Rivera, 2004)(ES/M0')min≧[3M0/(ɛπμR3)](v/β)3, where ES and M0' are radiated energy and seismic moment gained from observation, μ is the modulus of fault rigidity, ɛ is the parameter of ɛ=M0'/M0,M0 is seismic moment and R is rupture size on the fault, v and β are rupture speed and S-wave speed. From II and III crack extending model, we attempt to reconcile a uniform expression for calculate seismic radiation efficiency ηG, which can be used to restrict the upper limit efficiency and avoid the non-physics phenomenon that radiation efficiency is larger than 1. In ML 4.1 Shacheng earthquake sequence, the rupture speed of the main shock was about 0.86 of S-wave speed β according to MREC, closing to the Rayleigh wave speed, while the rupture speeds of the remained 28 aftershocks ranged from 0.05β to 0.55β. The rupture speed was 0.9β, and most of the aftershocks are no more than 0.35β using II and III crack extending model. In addition, the seismic radiation efficiencies for this earthquake sequence were: for the most aftershocks, the radiation efficiencies were less than 10%, inferring a low seismic efficiency, whereas the radiation efficiency was 78% for the main shock. The essential difference in the earthquake energy partition for the aftershock source dynamics indicated that the fracture energy dissipation could not be ignored in the source parameter estimation for the earthquake faulting, especially for small earthquakes. Otherwise, the radiated seismic energy could be overestimated or underestimated.

The concept of sustainable prefab modular housing made of natural fiber reinforced polymer (NFRP)

NASA Astrophysics Data System (ADS)

Setyowati, E.; Pandelaki, E. E.

2018-03-01

This research aims to formulate the concept of public housing based on research results on natural fiber reinforced polymer (FRP) material which has been done in the road map of research. Research output is the public housing design and specifications of FRP made of water hyacinths and coconut fiber. Method used is descriptive review of the concept based on references and material test which consists of density, water absorption, modulus of rupture (MOR), tensile strength, absorption coefficient and Sound Transmission Loss (STL). The entire tests of material were carried out in the laboratory of materials and construction, while the acoustic tests carried out using the impedance tubes method. The test results concluded that the FRP material may have a density between 0.2481 – 0.2777 g/cm3, the absorption coefficient is average of 0.450 – 0.900, the Modulus of Elasticity is between 4061 – 15193 kg/cm2, while the average of sound transmission loss is 52 – 59 dB. Furthermore, that the concept of public housing must be able to be the embryo of the concept of environment-friendly and low emissions housing.

Numerical Analysis of the Bending Properties of Cathay Poplar Glulam

PubMed Central

Gao, Ying; Wu, Yuxuan; Zhu, Xudong; Zhu, Lei; Yu, Zhiming; Wu, Yong

2015-01-01

This paper presents the formulae and finite element analysis models for predicting the Modulus of Elastic (MOE) and Modulus of Rupture (MOR) of Cathay poplar finger-jointed glulam. The formula of the MOE predicts the MOE of Cathay poplar glulam glued with one-component polyurethane precisely. Three formulae are used to predict the MOR, and Equation (12) predicts the MOR of Cathay poplar glulam precisely. The finite element analysis simulation results of both the MOE and MOR are similar to the experimental results. The predicted results of the finite element analysis are shown to be more accurate than those of the formulae, because the finite element analysis considers the glue layers, but the formulae do not. Three types of typical failure modes due to bending were summarized. The bending properties of Cathay poplar glulam were compared to those of Douglas fir glulam. The results show that Cathay poplar glulam has a lower stiffness, but a marginally higher strength. One-component polyurethane adhesive is shown to be more effective than resorcinol formaldehyde resin adhesive for Cathay poplar glulam. This study shows that Cathay poplar has the potential to be a glulam material in China. PMID:28793619

Effect of Ionizing Radiation on the Mechanical and Structural Properties of Graphite Fiber Reinforced Composites. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Wolf, Kay Woodroof

1982-01-01

Graphite/epoxy (T300/5208) and graphite/polyimide composites (C6000/PMR 15) were exposed to various levels of 0.5 MeV electron radiation with the maximum dose being 10,000 Mrad. A three point bending test was used to evaluate the ultimate stress and modulus of the composites. In all composites except transverse samples of C6000/PMR 15 ultimate stress values remained approximately constant or increased slightly. The modulus values remained approximately constant for all composite types regardless of the radiation level. Interfacial aspects of composites were studied. Interlaminar shear tests were performed on T300/5208 and C6000/PMR 15 composites irradiated to 10,000 Mrad. There was an initial increase in interlaminar shear strength (up to 1,000 Mrad) followed by a sharp decrease with further radiation exposure. Using scanning electron microscopy no visual differences in the mode of fracture could be detected between ruptured control samples and those exposed to various levels of radiation. Electron spectroscopy for chemical analysis (ESCA) revealed little change in the surface elements present in control and highly irradiated T300/5208 composite samples.

Complex earthquake rupture and local tsunamis

USGS Publications Warehouse

Geist, E.L.

2002-01-01

In contrast to far-field tsunami amplitudes that are fairly well predicted by the seismic moment of subduction zone earthquakes, there exists significant variation in the scaling of local tsunami amplitude with respect to seismic moment. From a global catalog of tsunami runup observations this variability is greatest for the most frequently occuring tsunamigenic subduction zone earthquakes in the magnitude range of 7 < Mw < 8.5. Variability in local tsunami runup scaling can be ascribed to tsunami source parameters that are independent of seismic moment: variations in the water depth in the source region, the combination of higher slip and lower shear modulus at shallow depth, and rupture complexity in the form of heterogeneous slip distribution patterns. The focus of this study is on the effect that rupture complexity has on the local tsunami wave field. A wide range of slip distribution patterns are generated using a stochastic, self-affine source model that is consistent with the falloff of far-field seismic displacement spectra at high frequencies. The synthetic slip distributions generated by the stochastic source model are discretized and the vertical displacement fields from point source elastic dislocation expressions are superimposed to compute the coseismic vertical displacement field. For shallow subduction zone earthquakes it is demonstrated that self-affine irregularities of the slip distribution result in significant variations in local tsunami amplitude. The effects of rupture complexity are less pronounced for earthquakes at greater depth or along faults with steep dip angles. For a test region along the Pacific coast of central Mexico, peak nearshore tsunami amplitude is calculated for a large number (N = 100) of synthetic slip distribution patterns, all with identical seismic moment (Mw = 8.1). Analysis of the results indicates that for earthquakes of a fixed location, geometry, and seismic moment, peak nearshore tsunami amplitude can vary by a factor of 3 or more. These results indicate that there is substantially more variation in the local tsunami wave field derived from the inherent complexity subduction zone earthquakes than predicted by a simple elastic dislocation model. Probabilistic methods that take into account variability in earthquake rupture processes are likely to yield more accurate assessments of tsunami hazards.

INVESTIGATION OF THE EFFECTS OF PROCESSING VARIABLES AND FABRICATION TECHNIQUES UPON THE PROPERTIES OF INTERMETALLIC COMPOUNDS. Technical Report No. 190-229. Progress Report No. 2 for July 1, 1960 to September 30, 1960

DOE Office of Scientific and Technical Information (OSTI.GOV)

Truesdale, R.; Lympany, B.; Klein, J.

1960-10-15

The optimum sintering temperatures of cold pressed NbBe/sub 12/, Nb/sub 2/Be/sub 17/ and Nb/sub 2/Be/sub 19/ were established as 3090. and 3090 deg F, respectively. The compound Nb/sub 2/Be/sub 17/ sintered to 97.5% of theoretical density. Sound 4-in.-square by l-in.-thick blocks of Nb/sub 2/Be/sub 17/ were fabricated and cut into transverse-rupture bars. A modulus of rupture strength of over 46.000 psi was measured at 2500 deg F. In the metallurgical phase. tungsten was found to be a suitable jacket material for the mechanical working of the niobium beryllides at 3000 deg F if protected from oxidation. Cera-kote. a refractory coating,more » sufficiently reduced tungsten oxidation for periods up to 1- hr. Two Nb/sub 2/Be/sub 17/ specimens were upset at 2750 deg F and 7500 psi. An upset of 48% was achieved. causing a slight increase in density and grain size. (auth)« less

Collagen-chitosan-glycerol bio-composite as artificial tympanic membrane for ruptured inner ear organ

NASA Astrophysics Data System (ADS)

Widiyanti, Prihartini; Setya Angtika, Rara; Githanadi, Brillyana; Hanif Kharisma, Ditya; Asyraf, Tarikh Omar; Wardani, Adita

2017-05-01

WHO data in 2012 shows that 5.3% of world population highly suffers from hearing loss and deafness. One of the deafness causes is rupture of tympanic membrane. Tympanic membrane damage which occurs often is perforated tympanic membrane, and it is also commonly known in medical term as tympanic membrane perforation. The causes, for instance, are high frequency of using earphones, traumatic accidents, noise, bacteria, viruses, and infectious microorganism. Tympanoplasty becomes the only treatment that can be widely accepted despite of deficiencies in postoperative complications. Therefore, this research aims to create artificial tympanic membrane made of natural materials such as type I collagen composited with chitosan and made of addition of glycerol to improve its mechanical strength and biodegradability. The method included the process of dissolving acetic acid in distilled water and mixation with chitosan. The solution is next added with glycerol and stirred to be homogeneous. After that, it was minted in petri dish and aerated before characterized. The sample characterization included tensile strength of which tensile test results showed that the value of the elasticity modulus tended to decrease with an increase in collagen concentration. The elasticity modulus values in a row for the variations of 7: 3, 8: 2, and 9: 1 were 35.10 MPa, 54,52MPa, and 47,45MPa respectively. The morphological test with 1000x, 2500x, and 5000x magnification showed their interaction in the formation of pores. Cytotoxicity results, moreover, showed that those samples were non-toxic and safe for the body due to the percentage of living cells. The sound absorption coefficient was between 1000 Hz - 2000 Hz which means that it could use as sound absorbing material. The antibacterial test results showed that all the sample variations were anti-bacterial due to the diameter of the clear zone. In conclusion, collagen and chitosan composite with addition of glycerol could be used for potential artificial tympanic for to its characterization

Postinjury biomechanics of Achilles tendon vary by sex and hormone status

PubMed Central

Fryhofer, George W.; Freedman, Benjamin R.; Hillin, Cody D.; Salka, Nabeel S.; Pardes, Adam M.; Weiss, Stephanie N.; Farber, Daniel C.

2016-01-01

Achilles tendon ruptures are common injuries. Sex differences are present in mechanical properties of uninjured Achilles tendon, but it remains unknown if these differences extend to tendon healing. We hypothesized that ovariectomized females (OVX) and males would exhibit inferior postinjury tendon properties compared with females. Male, female, and OVX Sprague-Dawley rats (n = 32/group) underwent acclimation and treadmill training before blunt transection of the Achilles tendon midsubstance. Injured hindlimbs were immobilized for 1 wk, followed by gradual return to activity and assessment of active and passive hindlimb function. Animals were euthanized at 3 or 6 wk postinjury to assess tendon structure, mechanics, and composition. Passive ankle stiffness and range of motion were superior in females at 3 wk; however, by 6 wk, passive and active function were similar in males and females but remained inferior in OVX. At 6 wk, female tendons had greater normalized secant modulus, viscoelastic behavior, and laxity compared with males. Normalized secant modulus, cross-sectional area and tendon glycosaminoglycan composition were inferior in OVX compared with females at 6 wk. Total fatigue cycles until tendon failure were similar among groups. Postinjury muscle fiber size was better preserved in females compared with males, and females had greater collagen III at the tendon injury site compared with males at 6 wk. Despite male and female Achilles tendons withstanding similar durations of fatigue loading, early passive hindlimb function and tendon mechanical properties, including secant modulus, suggest superior healing in females. Ovarian hormone loss was associated with inferior Achilles tendon healing. PMID:27633741

Laser-zone growth in a Ribbon-To-Ribbon, RTR, process silicon sheet growth development for the large area silicon sheet task of the low cost silicon solar array project

NASA Technical Reports Server (NTRS)

Gurtler, R. W.; Baghdadi, A.

1977-01-01

A ribbon-to-ribbon process was used for routine growth of samples for analysis and fabrication into solar cells. One lot of solar cells was completely evaluated: ribbon solar cell efficiencies averaged 9.23% with a highest efficiency of 11.7%. Spherical reflectors have demonstrated significant improvements in laser silicon coupling efficiencies. Material analyses were performed including silicon photovoltage and open circuit photovoltage diffusion length measurements, crystal morphology studies, modulus of rupture measurements, and annealing/gettering studies. An initial economic analysis was performed indicating that ribbon-to-ribbon add-on costs of $.10/watt might be expected in the early 1980's.

NDE of structural ceramics

NASA Technical Reports Server (NTRS)

Klima, S. J.; Vary, A.

1986-01-01

Radiographic, ultrasonic, scanning laser acoustic microscopy (SLAM), and thermo-acoustic microscopy techniques were used to characterize silicon nitride and silicon carbide modulus-of-rupture test specimens in various stages of fabrication. Conventional and microfocus X-ray techniques were found capable of detecting minute high density inclusions in as-received powders, green compacts, and fully densified specimens. Significant density gradients in sintered bars were observed by radiography, ultrasonic velocity, and SLAM. Ultrasonic attenuation was found sensitive to microstructural variations due to grain and void morphology and distribution. SLAM was also capable of detecting voids, inclusions and cracks in finished test bars. Consideration is given to the potential for applying thermo-acoustic microscopy techniques to green and densified ceramics. The detection probability statistics and some limitations of radiography and SLAM also are discussed.

Temperature distributions and thermal stresses in a graded zirconia/metal gas path seal system for aircraft gas turbine engines

NASA Technical Reports Server (NTRS)

Taylor, C. M.; Bill, R. C.

1978-01-01

A ceramic/metallic aircraft gas turbine outer gas path seal designed for improved engine performance was studied. Transient temperature and stress profiles in a test seal geometry were determined by numerical analysis. During a simulated engine deceleration cycle from sea-level takeoff to idle conditions, the maximum seal temperature occurred below the seal surface, therefore the top layer of the seal was probably subjected to tensile stresses exceeding the modulus of rupture. In the stress analysis both two- and three-dimensional finite element computer programs were used. Predicted trends of the simpler and more easily usable two-dimensional element programs were borne out by the three-dimensional finite element program results.

Etude de la degradation des refractaires aluminosiliceux par abrasion, chocs thermiques et corrosion par l'aluminium: Correlation et interaction des mecanismes

NASA Astrophysics Data System (ADS)

Ntakaburimvo, Nicodeme

Aluminosilicate refractories used for melting and holding furnaces on which the present work was focused are submitted to mechanical abuse such as abrasion, mechanical impact and erosion, on one hand; and to chemical degradation by corrosion, as well as to thermal stresses, mostly due to thermal shocks; on the other hand. This thesis is focused on four main objectives. The first one is related to the designing of an experimental set-up allowing abrasion testing of refractories. The second deals with the separate study of the deterioration of aluminosilicate refractories by abrasion, thermal shock and corrosion. The third is the correlation between these three mechanisms while the fourth is related to the interaction between thermal shock and corrosion. One of the contributions of this thesis is the realisation of the above mentioned experimental set-up, which permits to carry out refractories abrasion testing, as well as at room and high temperature, in the absence or in the presence of molten metal. The fact of testing refractory resistance when it is submitted separately and simultaneously to the action of dynamic corrosion, erosion and abrasion leads to the studying of the influence of each of these three mechanisms on the other. One of the characteristics of the designed set-up is the fact that it allows to adjust the seventy testing conditions according to the mechanical resistance of the test material. The other important point is related to the fact the abrasion tests were carried out in such manner to permit degradation quantification, otherwise than by the traditional method of loss of weight measurement; particularly by measuring the wear depth and the residual material properties, such as the rupture force and the strength. A perfect correlation was observed between the wear depth and the loss of weight, both being negatively correlated with the residual rupture force. The abrasion resistance was found to be globally positively correlated with the original mechanical material's properties such as the modulus of rupture, the toughness and the elastic modulus. However, for same mechanical resistance for bricks and castables, the latter were more degraded because of more microstructural defects they contain. Moreover, in case of the castables, the original surface facing the mould was more abraded than a rectified surface because of the segregation phenomenon. It has been shown in this study that the abrasion process has no longer effect on material's strength unless the cracks length it promotes is higher than that of the initial defects. (Abstract shortened by UMI.)

Tensile stress rupture behavior of a woven ceramic matrix composite in humid environments at intermediate temperature

NASA Astrophysics Data System (ADS)

Larochelle, Kevin J.

This study focused on moisture and intermediate temperature effects on the embrittlement phenomenon and stress rupture life of the ceramic matrix composite (CMC) made of Sylramic(TM) fibers with an in-situ layer of boron nitride (Syl-iBN), boron nitride interphase (BN), and SiC matrix (Syl-iBN/BN/SiC). Stress rupture tests were performed at 550°C or 750°C with moisture contents of 0.0, 0.2, or 0.6 atm partial pressure of water vapor, pH 2O. The CMC stress rupture strengths at 100 hrs at 550°C with 0.0, 0.2, or 0.6 atm pH2O were 75%, 65% and 51% of the monotonic room temperature tensile strength, respectively. At 750°C, the corresponding strengths were 67%, 51%, and 49%, respectively. Field Emission Scanning Electron Microscopy (FESEM) analysis showed that the amount of pesting by glass formations increased with time, temperature, and pH2O leading to embrittlement. Total embrittlement times for 550°C were estimated to be greater than 63 hrs for 0.0 atm pH2O greater than 38 hrs for 0.2 atm pH 2O and between 8 and 71 hrs for 0.6 atm pH2O. Corresponding estimated embrittlement times for the 750°C were greater than 83 hrs, between 13 and 71 hrs, and between 1 and 6 hrs. A time-dependent, phenomenological, Monte Carlo-type simulation of composite failure was developed. The simulated total embrittlement times for the 550°C cases were 300 hrs, 100 hrs, and 25 hrs for 0.0, 0.2, and 0.6 atm pH 2O, respectively. The corresponding embrittlement times for the 750°C cases were 300 hrs, 20 hrs, and 3 hrs. A detailed sensitivity analysis on the variables used in the model was conducted. The model was most sensitive to variation in the ultimate strength of the CMC at room temperature, the ultimate strength of the CMC at elevated temperature, and the reference strength of a fiber and it was least sensitive to variation in the modulus of elasticity of the matrix and fiber. The sensitivity analysis showed that the stress ruptures curves generated by variation in the total embrittlement time simulate the trends in the experimental data. This research showed that the degree of stress rupture strength degradation increases with temperature, moisture content level, and exposure time.

The Feasibility of Sugar Palm (Arenga pinnata) Trunk for Raw Material of Parquet (Wood Flooring)

NASA Astrophysics Data System (ADS)

Nuryawan, A.; Tarigan, A.; Hakim, L.

2017-03-01

In the market, parquet was made from high density wood such as teak, merbau, kempas, ulin, oak, lime, maple, or other high density wood. Parquet has been used for flooring in specific buildings, for instance sport hall, library, commercial building (i.e hotel lobby, hypermarket), and office building. Because of the scarcity of high density wood nowadays and in order to find out the alternative material for wood flooring, the utilization of sugar palm trunk was considered. In this contribution, unproductive sugar palm tree was cut down and divided into three sections using chain saw, namely bottom, middle, and tip. For each section, physical and mechanical samples testing were made according to British Standard 373:1957 for small clear specimen. Investigation of both properties was done in ambient temperature with at least three replications. Instron UTM (Universal Testing Machine) was used to evaluate the mechanical properties. Results of the physical testing (density, moisture content and tangential shrinkage) showed the entire trunk was suitable for raw material of parquet. However, the results of mechanical testing (hardness, MOE/modulus of elasticity, MOR/modulus of rupture, and compression perpendicular to grain) showed only bottom and middle parts were suitable for raw material of parquet while the upper part was vice versa.

Fabrication and mechanical characterization of a polyvinyl alcohol sponge for tissue engineering applications.

PubMed

Karimi, A; Navidbakhsh, M; Faghihi, S

2014-05-01

Polyvinyl alcohol (PVA) sponges are widely used for clinical applications, including ophthalmic surgical treatments, wound healing and tissue engineering. There is, however, a lack of sufficient data on the mechanical properties of PVA sponges. In this study, a biomechanical method is used to characterize the elastic modulus, maximum stress and strain as well as the swelling ratio of a fabricated PVA sponge (P-sponge) and it is compared with two commercially available PVA sponges (CENEFOM and EYETEC). The results indicate that the elastic modulus of the P-sponge is 5.32% and 13.45% lower than that of the CENEFOM and EYETEC sponges, while it bears 4.11% more and 10.37% less stress compared to the CENEFOM and EYETEC sponges, respectively. The P-sponge shows a maximum strain of 32% more than the EYETEC sponge as well as a 26.78% higher swelling ratio, which is a significantly higher absorbency compared to the CENEFOM. It is believed that the results of this study would help for a better understanding of the extension, rupture and swelling mechanism of PVA sponges, which could lead to crucial improvement in the design and application of PVA-based materials in ophthalmic and plastic surgeries as well as wound healing and tissue engineering.

Photosynthetic, hydraulic and biomechanical responses of Juglans californica shoots to wildfire.

PubMed

Utsumi, Yasuhiro; Bobich, Edward G; Ewers, Frank W

2010-10-01

Leaf gas exchange and stem xylem hydraulic and mechanical properties were studied for unburned adults and resprouting burned Juglans californica (southern California black walnut) trees 1 year after a fire to explore possible trade-offs between mechanical and hydraulic properties of plants. The CO(2) uptake rates and stomatal conductance were 2-3 times greater for resprouting trees than for unburned adults. Both predawn and midday water potentials were more negative for unburned adult trees, indicating that the stems were experiencing greater water stress than the stems of resprouting trees. In addition, the xylem specific conductivity was similar in the two growth forms, even though the stems of resprouting trees were less vulnerable to water-stress-induced embolism than similar diameter, but older, stems of adult trees. The reduced vulnerability may have been due to less cavitation fatigue in stems of resprouts. The modulus of elasticity, modulus of rupture and xylem density were all greater for resprouts, indicating that resprouts have greater mechanical strength than do adult trees. The data suggest that there is no trade-off between stem mechanical strength and shoot hydraulic and photosynthetic efficiency in resprouts, which may have implications for the success of this species in the fire-prone plant communities of southern California.

Inorganic polymers from laterite using activation with phosphoric acid and alkaline sodium silicate solution: Mechanical and microstructural properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lassinantti Gualtieri, Magdalena, E-mail: magdalena.gualtieri@unimore.it; Romagnoli, Marcello; Pollastri, Simone

2015-01-15

Geopolymers from laterite, an iron-rich soil available in developing countries, have great potential as building materials. In this work, laterite from Togo (Africa) was used to prepare geopolymers using both phosphoric acid and alkaline sodium silicate solution. Microstructural properties were investigated by scanning electron microscopy, X-ray powder diffraction and mercury porosimetry, whereas thermal properties were evaluated by thermal analyses. The local environment of iron was studied by X-ray Absorption Spectroscopy (XANES region). The mechanical properties were determined. Modulus of Rupture and Young's modulus fell in the ranges 3.3–4.5 MPa and 12–33 GPa, respectively, rendering the materials good candidates for constructionmore » purposes. Heating above 900 °C results in weight-gain, presumably due to iron redox reactions. X-ray Absorption Spectroscopy data evidence changes in the chemical and structural environments of iron following thermal treatment of geopolymers. These changes indicate interaction between the geopolymer structure and iron during heating, possibly leading to redox properties. -- Highlights: •Geopolymerization of laterite is promising for fabrication of building materials. •Both phosphoric acid and alkaline sodium silicate solution can be used for activation. •Thermally activated redox properties of the inorganic polymers were observed.« less

Engineering an in vitro model of a functional ligament from bone to bone.

PubMed

Paxton, Jennifer Z; Grover, Liam M; Baar, Keith

2010-11-01

For musculoskeletal tissues that transmit loads during movement, the interfaces between tissues are essential to minimizing injury. Therefore, the reproduction of functional interfaces within engineered musculoskeletal tissues is critical to the successful transfer of the technology to the clinic. The goal of this work was to rapidly engineer ligament equivalents in vitro that contained both the soft tissue sinew and a hard tissue bone mimetic. This goal was achieved using cast brushite (CaHPO(4)·2H(2)O) anchors to mimic bone and a fibrin gel embedded with fibroblasts to create the sinew. The constructs formed within 7 days. Fourteen days after seeding, the interface between the brushite and sinew could withstand a stress of 9.51 ± 1.7  kPa before failure and the sinew reached a Young's modulus value of 0.16 ± 0.03  MPa. Treatment with ascorbic acid and proline increased the collagen content of the sinew (from 1.34% ± 0.2% to 8.34% ± 0.37%), strength of the interface (29.24 ± 6  kPa), and modulus of the sinew (2.69 ± 0.25  MPa). Adding transforming growth factor-β resulted in a further increase in collagen (11.25% ± 0.39%), interface strength (42 ± 8  kPa), and sinew modulus (5.46 ± 0.68  MPa). Both scanning electron and Raman microscopy suggested that the interface between the brushite and sinew mimics the in vivo tidemark at the enthesis. This work describes a major step toward the development of tissue-engineered ligaments for the repair of ligament ruptures in humans.

Thermally induced gelling of oil-in-water emulsions comprising partially crystallized droplets: the impact of interfacial crystals.

PubMed

Thivilliers, Florence; Laurichesse, Eric; Saadaoui, Hassan; Leal-Calderon, Fernando; Schmitt, Véronique

2008-12-02

We produced triglyceride-in-water emulsions comprising partially crystallized droplets, stabilized by a mixture of protein and low molecular weight surfactant. The emulsions were emulsified in the melted state of the oil phase and stored at low temperature (4 degrees C) right after fabrication to induce oil crystallization. The systems were then warmed to room temperature for a short period of time and cooled again to 4 degrees C. Owing to this treatment referred to as temperature cycling or "tempering", the initially fluid emulsions turned into hard gels. We followed the bulk rheological properties of the materials during and after tempering. The storage modulus, G', exhibited a dramatic increase when tempering was applied. We showed that the systems evolved following two distinct regimes that depend on the average droplet size and on the surfactant-to-protein molar ratio. Gelling may involve partial coalescence of the droplets, i.e., film rupturing with no further shape relaxation because of the solid nature of the droplets. Alternatively, gelling may occur without film rupturing, and is reminiscent of a jamming transition induced by surface roughness. We discussed the origin of these two mechanisms in terms of the properties (size and protuberance) of the interfacial oil crystals.

Finite-fault slip model of the 2016 Mw 7.5 Chiloé earthquake, southern Chile, estimated from Sentinel-1 data

NASA Astrophysics Data System (ADS)

Xu, Wenbin

2017-05-01

Subduction earthquakes have been widely studied in the Chilean subduction zone, but earthquakes occurring in its southern part have attracted less research interest primarily due to its lower rate of seismic activity. Here I use Sentinel-1 interferometric synthetic aperture radar (InSAR) data and range offset measurements to generate coseismic crustal deformation maps of the 2016 Mw 7.5 Chiloé earthquake in southern Chile. I find a concentrated crustal deformation with ground displacement of approximately 50 cm in the southern part of the Chiloé island. The best fitting fault model shows a pure thrust-fault motion on a shallow dipping plane orienting 4° NNE. The InSAR-determined moment is 2.4 × 1020 Nm with a shear modulus of 30 GPa, equivalent to Mw 7.56, which is slightly lower than the seismic moment. The model shows that the slip did not reach the trench, and it reruptured part of the fault that ruptured in the 1960 Mw 9.5 earthquake. The 2016 event has only released a small portion of the accumulated strain energy on the 1960 rupture zone, suggesting that the seismic hazard of future great earthquakes in southern Chile is high.

Effect of vacancies on the mechanical properties of phosphorene nanotubes.

PubMed

Sorkin, V; Zhang, Y W

2018-06-08

Using density functional tight-binding method, we studied the mechanical properties, deformation and failure of armchair (AC) and zigzag (ZZ) phosphorene nanotubes (PNTs) with monovacancies and divacancies subjected to uniaxial tensile strain. We found that divacancies in AC PNTs and monovacancies in ZZ PNTs possess the lowest vacancy formation energy, which decreases with the tube diameter in AC PNTs and increases in ZZ PNTs. The Young's modulus is reduced, while the radial and thickness Poisson's ratios are increased by hosted vacancies. In defective AC PNTs, deformation involves fracture of the intra-pucker bonds and formation of the new inter-pucker bonds at a critical strain, and the most stretched bonds around the vacancy rupture first, triggering a sequence of the structural transformations terminated by the ultimate failure. The critical strain of AC PNTs is reduced significantly by hosted vacancies, whereas their effect on the critical stress is relatively weaker. Defective ZZ PNTs fail in a brittle-like manner once the most stretched bonds around a vacancy rupture, and vacancies are able to significantly reduce the failure strain but only moderately reduce the failure stress of ZZ PNTs. The understandings revealed here on the mechanical properties and the deformation and failure mechanisms of PNTs provide useful guidelines for their design and fabrication as building blocks in nanodevices.

Effect of vacancies on the mechanical properties of phosphorene nanotubes

NASA Astrophysics Data System (ADS)

Sorkin, V.; Zhang, Y. W.

2018-06-01

Using density functional tight-binding method, we studied the mechanical properties, deformation and failure of armchair (AC) and zigzag (ZZ) phosphorene nanotubes (PNTs) with monovacancies and divacancies subjected to uniaxial tensile strain. We found that divacancies in AC PNTs and monovacancies in ZZ PNTs possess the lowest vacancy formation energy, which decreases with the tube diameter in AC PNTs and increases in ZZ PNTs. The Young’s modulus is reduced, while the radial and thickness Poisson’s ratios are increased by hosted vacancies. In defective AC PNTs, deformation involves fracture of the intra-pucker bonds and formation of the new inter-pucker bonds at a critical strain, and the most stretched bonds around the vacancy rupture first, triggering a sequence of the structural transformations terminated by the ultimate failure. The critical strain of AC PNTs is reduced significantly by hosted vacancies, whereas their effect on the critical stress is relatively weaker. Defective ZZ PNTs fail in a brittle-like manner once the most stretched bonds around a vacancy rupture, and vacancies are able to significantly reduce the failure strain but only moderately reduce the failure stress of ZZ PNTs. The understandings revealed here on the mechanical properties and the deformation and failure mechanisms of PNTs provide useful guidelines for their design and fabrication as building blocks in nanodevices.

Elastic properties and mechanical stability of chiral and filled viral capsids

NASA Astrophysics Data System (ADS)

Buenemann, Mathias; Lenz, Peter

2008-11-01

The elasticity and mechanical stability of empty and filled viral capsids under external force loading are studied in a combined analytical and numerical approach. We analyze the influence of capsid structure and chirality on the mechanical properties. We find that generally skew shells have lower stretching energy. For large Föppl-von Kármán numbers γ (γ≈105) , skew structures are stiffer in their elastic response than nonchiral ones. The discrete structure of the capsules not only leads to buckling for large γ but also influences the breakage behavior of capsules below the buckling threshold: the rupture force shows a γ1/4 scaling rather than a γ1/2 scaling as expected from our analytical results for continuous shells. Filled viral capsids are exposed to internal anisotropic pressure distributions arising from regularly packaged DNA coils. We analyze their influence on the elastic properties and rupture behavior and we discuss possible experimental consequences. Finally, we numerically investigate specific sets of parameters corresponding to specific phages such as ϕ29 and cowpea chlorotic mottle virus (CCMV). From the experimentally measured spring constants we make predictions about specific material parameters (such as bending rigidity and Young’s modulus) for both empty and filled capsids.

Ceramic Technology Project data base: September 1992 summary report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keyes, B.L.P.

Data presented in this report represent an intense effort to improve processing methods, testing methods, and general mechanical properties (rupture modulus, tensile, creep, stress-rupture, dynamic and cyclic fatigue, fracture toughness) of candidate ceramics for use in advanced heat engines. This work was performed by many facilities and represents only a small part of the data generated by the Ceramic Technology Project (CTP) since 1986. Materials discussed include GTE PY6, GN-10, NT-154, NT-164, SN-260, SN-251, SN-252, AY6, silicon nitride combined with rare-earth oxides, Y-TZP, ZTA, NC-433, NT-230, Hexoloy SA, MgO-PSZ-to-MgO-PSZ joints, MgO-PSZ-to-cast iron, and a few whisker/fiber-reinforced ceramics. Information in thismore » report was taken from the project`s semiannual and bimonthly progress reports and from final reports summarizing the results of individual studies. Test results are presented in tabular form and in graphs. All data, including test rig descriptions and material characterizations, are stored in the CTP data base and are available to all project participants on request. The objective of this report is to make available the test results from these studies but not to draw conclusions from those data.« less

Corrosion Product Film-Induced Stress Facilitates Stress Corrosion Cracking

PubMed Central

Wang, Wenwen; Zhang, Zhiliang; Ren, Xuechong; Guan, Yongjun; Su, Yanjing

2015-01-01

Finite element analyses were conducted to clarify the role of corrosion product films (CPFs) in stress corrosion cracking (SCC). Flat and U-shaped edge-notched specimens were investigated in terms of the CPF-induced stress in the metallic substrate and the stress in the CPF. For a U-shaped edge-notched specimen, the stress field in front of the notch tip is affected by the Young’s modulus of the CPF and the CPF thickness and notch geometry. The CPF-induced tensile stress in the metallic substrate is superimposed on the applied load to increase the crack tip strain and facilitate localized plasticity deformation. In addition, the stress in the CPF surface contributes to the rupture of the CPFs. The results provide physical insights into the role of CPFs in SCC. PMID:26066367

Dynamics of the earthquake source: An investigation of conditions under which velocity-weakening friction allows a self-healing versus crack-like mode of rupture

NASA Astrophysics Data System (ADS)

Zheng, Gutuan

Earthquake rupture processes occur by two basic modes: the expanding crack-like and the self-healing. For the expanding crack-like mode, ruptures on the fault keep expanding and seismic slips continue growing unless stopped by unbreakable barriers. For the self-healing mode, ruptures occur as a slip pulse propagating along the fault, with complete cessation of slip behind the pulse. A self-healing mode of rupture occurs on a velocity weakening fault under the following conditions: (1) Under-stressing; the background loading should be sufficiently low that no classical cracks can survive; (2) Aging; the rate- and state-dependent friction laws must allow restrengthening in truly stationary contact (Perrin et al., 1995). When V>0 we have tausb{strength}=tau, with tausb{strength}=tausb{strength}(V,theta) and tau=tausbsp{o}{b}-(mu/2c)V+phi along the fault surface, where tausb{strength} is the fault strength and tau is the stress. Other notations are slip velocity V, state variable theta, shear modulus mu, and shear wave speed c. tausbsp{o}{b} is the remote background loading and phi is the elastodynamic functional representing the effects of spatially non-uniform slip history. An idealized condition of spatially uniform steady state slip leads to a steady state strength curve tausb{strength}=tausb{SS}(V) and a radiation damping line tau=tausbsp{o}{b}-(mu/2c)V. Then a certain range of "under-stressing" is found by requiring that tau≤tausb{strength}, i.e., tausbsp{o}{b}-(mu/2c)V≤tausb{SS}(V), is true for all V. The maximum value of such tausbsp{o}{b} is called tausb{pulse}. An indefinitely expanding crack-like rupture solution does not exist if tausbsp{o}{b}≤tausb{pulse}, implying only the pulse, either growing indefinitely or arresting, can be the solution. For tausbsp{o}{b}>tausb{pulse}, we further classify the rupture patterns based on a parameter T, which should reflect effects of both velocity weakening of the fault and the background loading. First a characteristic dynamic velocity Vsb{dyna} is found as the (larger) velocity solution at which curves tau=tausb{SS}(V) and tau=tausbsp{o}{b}-(mu/2c)V intersect. Then T is quantitatively defined as the slope ratio of these two curves at Vsb{dyna}, i.e., T={-}dtausb{SS}(Vsb{dyna})/dV)/(mu/2c). T=1 at tausbsp{o}{b}=tausb{pulse}, and T decreases with further increase of tausbsp{o}{b}. So T near 1 means tausbsp{o}{b} is close to tausb{pulse} and, numerical simulations with aging laws show that the rupture mode tends to be pulse-like. T near 0 means little continuing velocity weakening at Vsb{dyna}, and simulations show that the apparent rupture mode is crack-like. T near 0.5 is associated with transitional behavior between the crack-like and self-healing modes. If stresses on a natural fault are low on average in the sense discussed here, then they will not allow the crack-like mode, the self-healing slip pulse should be a common phenomenon. Both submodes of it, either growing or decaying with propagation distance, are important mechanisms in adjustment of the stress distribution on the fault surface.

Boron-carbide-aluminum and boron-carbide-reactive metal cermets

DOEpatents

Halverson, Danny C.; Pyzik, Aleksander J.; Aksay, Ilhan A.

1986-01-01

Hard, tough, lightweight boron-carbide-reactive metal composites, particularly boron-carbide-aluminum composites, are produced. These composites have compositions with a plurality of phases. A method is provided, including the steps of wetting and reacting the starting materials, by which the microstructures in the resulting composites can be controllably selected. Starting compositions, reaction temperatures, reaction times, and reaction atmospheres are parameters for controlling the process and resulting compositions. The ceramic phases are homogeneously distributed in the metal phases and adhesive forces at ceramic-metal interfaces are maximized. An initial consolidation step is used to achieve fully dense composites. Microstructures of boron-carbide-aluminum cermets have been produced with modulus of rupture exceeding 110 ksi and fracture toughness exceeding 12 ksi.sqroot.in. These composites and methods can be used to form a variety of structural elements.

Radial basis function network learns ceramic processing and predicts related strength and density

NASA Technical Reports Server (NTRS)

Cios, Krzysztof J.; Baaklini, George Y.; Vary, Alex; Tjia, Robert E.

1993-01-01

Radial basis function (RBF) neural networks were trained using the data from 273 Si3N4 modulus of rupture (MOR) bars which were tested at room temperature and 135 MOR bars which were tested at 1370 C. Milling time, sintering time, and sintering gas pressure were the processing parameters used as the input features. Flexural strength and density were the outputs by which the RBF networks were assessed. The 'nodes-at-data-points' method was used to set the hidden layer centers and output layer training used the gradient descent method. The RBF network predicted strength with an average error of less than 12 percent and density with an average error of less than 2 percent. Further, the RBF network demonstrated a potential for optimizing and accelerating the development and processing of ceramic materials.

Impact of Chronic Hypoxia on Proximal Pulmonary Artery Wave Propagation and Mechanical Properties in Rats.

PubMed

Su, Junjing; Logan, Charmilie C; Hughes, Alun D; Parker, Kim H; Dhutia, Niti M; Danielsen, Carl Christian; Simonsen, Ulf

2018-03-16

Arterial stiffness and wave reflection are important components of the ventricular afterload. Therefore, we aimed to assess the arterial wave characteristics and mechanical properties of the proximal pulmonary arteries (PAs) in the hypoxic pulmonary hypertensive rat model. After 21 days in normoxic or hypoxic chambers (24 animals in each group), the animals underwent transthoracic echocardiography and pulmonary artery catheterization with a dual-tipped pressure and Doppler flow sensor wire. Wave intensity analysis (WIA) was performed. Artery rings obtained from the pulmonary trunk, right and left PAs and the aorta were subjected to a tensile test to rupture. Collagen and elastin content was determined. In hypoxic rats, proximal PA wall thickness, collagen content, tensile strength per unit collagen, maximal elastic modulus and wall viscosity increased; while the elastin:collagen ratio and arterial distensibility decreased. Arterial pulse wave velocity was also increased and the increase was more prominent in vivo than ex vivo. Wave intensity was similar in the hypoxic and normoxic animals with negligible wave reflection. In contrast, aortic maximal elastic modulus remained unchanged, while the wall viscosity decreased. There was no evidence of altered arterial wave propagation in the proximal PAs of hypoxic rats, while the extracellular matrix protein composition altered and the collagen tensile strength increased. This was accompanied by altered mechanical properties in vivo and ex vivo.

Magnesium Oxide Nanoparticles Reinforced Electrospun Alginate-Based Nanofibrous Scaffolds with Improved Physical Properties

PubMed Central

Mantilaka, M. M. M. G. P. G.; Goh, K. L.; Ratnayake, S. P.; Amaratunga, G. A. J.; de Silva, K. M. Nalin

2017-01-01

Mechanically robust alginate-based nanofibrous scaffolds were successfully fabricated by electrospinning method to mimic the natural extracellular matrix structure which benefits development and regeneration of tissues. Alginate-based nanofibres were electrospun from an alginate/poly(vinyl alcohol) (PVA) polyelectrolyte complex. SEM images revealed the spinnability of the complex composite nanofibrous scaffolds, showing randomly oriented, ultrafine, and virtually defects-free alginate-based/MgO nanofibrous scaffolds. Here, it is shown that an alginate/PVA complex scaffold, blended with near-spherical MgO nanoparticles (⌀ 45 nm) at a predetermined concentration (10% (w/w)), is electrospinnable to produce a complex composite nanofibrous scaffold with enhanced mechanical stability. For the comparison purpose, chemically cross-linked electrospun alginate-based scaffolds were also fabricated. Tensile test to rupture revealed the significant differences in the tensile strength and elastic modulus among the alginate scaffolds, alginate/MgO scaffolds, and cross-linked alginate scaffolds (P < 0.05). In contrast to cross-linked alginate scaffolds, alginate/MgO scaffolds yielded the highest tensile strength and elastic modulus while preserving the interfibre porosity of the scaffolds. According to the thermogravimetric analysis, MgO reinforced alginate nanofibrous scaffolds exhibited improved thermal stability. These novel alginate-based/MgO scaffolds are economical and versatile and may be further optimised for use as extracellular matrix substitutes for repair and regeneration of tissues. PMID:28694826

Biomechanics of Atherosclerotic Coronary Plaque: Site, Stability and In Vivo Elasticity Modeling

PubMed Central

Ohayon, Jacques; Finet, Gérard; Le Floc’h, Simon; Cloutier, Guy; Gharib, Ahmed M.; Heroux, Julie; Pettigrew, Roderic I.

2016-01-01

Coronary atheroma develop in local sites that are widely variable among patients and are considerably variable in their vulnerability for rupture. This article summarizes studies conducted by our collaborative laboratories on predictive biomechanical modeling of coronary plaques. It aims to give insights into the role of biomechanics in the development and localization of atherosclerosis, the morphologic features that determine vulnerable plaque stability, and emerging in vivo imaging techniques that may detect and characterize vulnerable plaque. Composite biomechanical and hemodynamic factors that influence the actual site of development of plaques have been studied. Plaque vulnerability, in vivo, is more challenging to assess. Important steps have been made in defining the biomechanical factors that are predictive of plaque rupture and the likelihood of this occurring if characteristic features are known. A critical key in defining plaque vulnerability is the accurate quantification of both the morphology and the mechanical properties of the diseased arteries. Recently, an early IVUS based palpography technique developed to assess local strain, elasticity and mechanical instabilities has been successfully revisited and improved to account for complex plaque geometries. This is based on an initial best estimation of the plaque components’ contours, allowing subsequent iteration for elastic modulus assessment as a basis for plaque stability determination. The improved method has also been preliminarily evaluated in patients with successful histologic correlation. Further clinical evaluation and refinement are on the horizon. PMID:24043605

Vulnerable Atherosclerotic Plaque Elasticity Reconstruction Based on a Segmentation-Driven Optimization Procedure Using Strain Measurements: Theoretical Framework

PubMed Central

Le Floc’h, Simon; Tracqui, Philippe; Finet, Gérard; Gharib, Ahmed M.; Maurice, Roch L.; Cloutier, Guy; Pettigrew, Roderic I.

2016-01-01

It is now recognized that prediction of the vulnerable coronary plaque rupture requires not only an accurate quantification of fibrous cap thickness and necrotic core morphology but also a precise knowledge of the mechanical properties of plaque components. Indeed, such knowledge would allow a precise evaluation of the peak cap-stress amplitude, which is known to be a good biomechanical predictor of plaque rupture. Several studies have been performed to reconstruct a Young’s modulus map from strain elastograms. It seems that the main issue for improving such methods does not rely on the optimization algorithm itself, but rather on preconditioning requiring the best estimation of the plaque components’ contours. The present theoretical study was therefore designed to develop: 1) a preconditioning model to extract the plaque morphology in order to initiate the optimization process, and 2) an approach combining a dynamic segmentation method with an optimization procedure to highlight the modulogram of the atherosclerotic plaque. This methodology, based on the continuum mechanics theory prescribing the strain field, was successfully applied to seven intravascular ultrasound coronary lesion morphologies. The reconstructed cap thickness, necrotic core area, calcium area, and the Young’s moduli of the calcium, necrotic core, and fibrosis were obtained with mean relative errors of 12%, 4% and 1%, 43%, 32%, and 2%, respectively. PMID:19164080

The effect of strain and age on the mechanical properties of rat Achilles tendons

PubMed Central

Vafek, Emily C.; Plate, Johannes F.; Friedman, Eric; Mannava, Sandeep; Scott, Aaron T.; Danelson, Kerry A.

2017-01-01

Summary Background Achilles tendon (AT) ruptures are common in the middle age population; however, the pathophysiology and influence of age on AT ruptures is not fully understood. This study evaluates the effect and interactions between, strain and age on the in vitro biomechanical properties of ATs. Methods Bilateral ATs were harvested from 17 young (8 months) and 14 middle-aged (24 months) rats and underwent stress-relaxation using Fung’s quasilinear viscoelastic (QLV) modeling and load-to-failure testing. Results The initial viscoelastic response (parameter B) in middle-age animals was dependent on the amount of strain applied to the tendon and was significantly increased in middle-aged animals at higher strain. Higher strain in older animals led to a prolonged relaxation time (parameter tau 2). There was a trend toward an increased magnitude of the relaxation response (parameter C) at higher strain in the middle-aged animals. Middle-aged animals had a significantly lower mean stress at ultimate failure (p=0.01), while Young’s modulus was similar in both groups (p=0.46). Conclusions The passive biomechanical properties of the rat AT change with age and the influence stress-relaxation response of the AT, thereby possibly predisposing the AT of older animals to fail at lower loads compared to younger animals. Level of evidence Not applicable, this is a basic science study. PMID:29387650

An analytical model to predict interstitial lubrication of cartilage in migrating contact areas.

PubMed

Moore, A C; Burris, D L

2014-01-03

For nearly a century, articular cartilage has been known for its exceptional tribological properties. For nearly as long, there have been research efforts to elucidate the responsible mechanisms for application toward biomimetic bearing applications. It is now widely accepted that interstitial fluid pressurization is the primary mechanism responsible for the unusual lubrication and load bearing properties of cartilage. Although the biomechanics community has developed elegant mathematical theories describing the coupling of solid and fluid (biphasic) mechanics and its role in interstitial lubrication, quantitative gaps in our understanding of cartilage tribology have inhibited our ability to predict how tribological conditions and material properties impact tissue function. This paper presents an analytical model of the interstitial lubrication of biphasic materials under migrating contact conditions. Although finite element and other numerical models of cartilage mechanics exist, they typically neglect the important role of the collagen network and are limited to a specific set of input conditions, which limits general applicability. The simplified approach taken in this work aims to capture the broader underlying physics as a starting point for further model development. In agreement with existing literature, the model indicates that a large Peclet number, Pe, is necessary for effective interstitial lubrication. It also predicts that the tensile modulus must be large relative to the compressive modulus. This explains why hydrogels and other biphasic materials do not provide significant interstitial pressure under high Pe conditions. The model quantitatively agrees with in-situ measurements of interstitial load support and the results have interesting implications for tissue engineering and osteoarthritis problems. This paper suggests that a low tensile modulus (from chondromalacia or local collagen rupture after impact, for example) may disrupt interstitial pressurization, increase shear stresses, and activate a condition of progressive surface damage as a potential precursor of osteoarthritis. © 2013 Elsevier Ltd. All rights reserved.

Elastomer Reinforced with Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Hudson, Jared L.; Krishnamoorti, Ramanan

2009-01-01

Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates.

PubMed

Siringi, Gideon; Abolmaali, Ali; Aswath, Pranesh B

2015-01-01

Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA.

Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

PubMed Central

Siringi, Gideon; Abolmaali, Ali; Aswath, Pranesh B.

2015-01-01

Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA. PMID:26161440

Fatigue behavior of a cross-ply ceramic matrix composite subjected to tension-tension cycling with hold time. Master`s thesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grant, S.A.

This study was carried out to investigate the elevated temperature behavior of the SiC-MAS5 cross- ply (O/9O)4S ceramic matrix composite manufactured by Corning Inc. to fatigue with loading waveforms that combine the characteristics of stress rupture and high cycle fatigue. The test results were compiled in the form of S-N (cycles to failure), S-T (exposure time versus cycles to failure), S-S (energy exposure versus cycles to failure), normalized modulus degradation, strain progression, and hysteresis loop progression. From the mechanical behavior demonstrated by these curves, relationships between the effect of the environment and loading waveform were developed. In addition, a post-mortemmore » SEM analysis of the fracture surface was conducted and the results compared to the mechanical behavior.« less

Comparison of the biomechanical properties of rottweiler and racing greyhound cranial cruciate ligaments.

PubMed

Wingfield, C; Amis, A A; Stead, A C; Law, H T

2000-07-01

An in vitro study of rottweiler and racing greyhound cranial cruciate ligaments revealed that the rottweiler ligaments had a significantly greater cross-sectional area at their distal attachments. Mechanical testing showed that the ultimate load related to body mass was significantly higher in the extended racing greyhound stifle during cranial tibial loading to failure, as were linear stiffness, tensile strength and tangent modulus. During ligament axis loading to failure, the only significant difference in structural and mechanical properties recorded between the two breeds was a greater ultimate strain for the greyhound ligament with the stifle joint flexed. Energy absorbed by the ligament complex at failure during cranial tibial loading was twice that for ligament axis loading for both breeds. The clinical significance is that the rottweiler cranial cruciate ligament is more vulnerable to damage as it requires half the load per unit body mass that the greyhound requires to cause a rupture.

Experimental results of temperature response to stress change: An indication of the physics of earthquake rupture propagation

NASA Astrophysics Data System (ADS)

Lin, W.; Yang, X.; Tadai, O.; Zeng, X.; Yeh, E. C.; Yu, C.; Hatakeda, K.; Xu, H.; Xu, Z.

2016-12-01

As a result of the earthquake rupture propagation, stress on the earthquake fault and in the hanging wall and in the footwall coseismically drops. Based on the thermo-elasticity theory, the temperature of rocks may change associated with coseismic stress change at the same time as their elastic deformation. This coseismic temperature change is one of the physics of earthquake rupture propagation, however has not been noted and expressly addressed before. To understand this temperature issue, we conducted laboratory experiments to quantitatively investigate temperatures response of rocks to rapid stress change of various typical rocks. Consequently, we developed a hydrostatic compression experimental equipment for rock samples with a high resolution temperature measuring system. This enable us to rapidly load and/or unload the confining pressure. As experimental rock samples, we collected 15 representative rocks from various scientific drilling projects and outcrops of earthquake faults, and quarries in the world. The rock types include sandstone, siltstone, limestone, granite, basalt, tuff etc. Based on the classical thermo-elastic theory, a conventional relationship between the temperature change (dT) of rock samples and the confining pressure change (dP) in the hydrostatic compression system under adiabatic condition can be expressed as a linear function. Therefore, we can measure the adiabatic pressure derivative of temperature (dT/dP) directly by monitoring changes of rock sample temperature and confining pressure during the rapidly loading and unloading processes. As preliminary results of the experiments, the data of 15 rock samples showed that i) the adiabatic pressure derivative of temperature (dT/dP) of most rocks are about 1.5 6.2 mK/MPa; ii) the dT/dP of sedimentary rocks is larger than igneous and metamorphic rocks; iii) a good linear correlation between dT/dP and the rock's bulk modulus was recognized.

Estimates of stress drop and crustal tectonic stress from the 27 February 2010 Maule, Chile, earthquake: Implications for fault strength

USGS Publications Warehouse

Luttrell, K.M.; Tong, X.; Sandwell, D.T.; Brooks, B.A.; Bevis, M.G.

2011-01-01

The great 27 February 2010 Mw 8.8 earthquake off the coast of southern Chile ruptured a ???600 km length of subduction zone. In this paper, we make two independent estimates of shear stress in the crust in the region of the Chile earthquake. First, we use a coseismic slip model constrained by geodetic observations from interferometric synthetic aperture radar (InSAR) and GPS to derive a spatially variable estimate of the change in static shear stress along the ruptured fault. Second, we use a static force balance model to constrain the crustal shear stress required to simultaneously support observed fore-arc topography and the stress orientation indicated by the earthquake focal mechanism. This includes the derivation of a semianalytic solution for the stress field exerted by surface and Moho topography loading the crust. We find that the deviatoric stress exerted by topography is minimized in the limit when the crust is considered an incompressible elastic solid, with a Poisson ratio of 0.5, and is independent of Young's modulus. This places a strict lower bound on the critical stress state maintained by the crust supporting plastically deformed accretionary wedge topography. We estimate the coseismic shear stress change from the Maule event ranged from-6 MPa (stress increase) to 17 MPa (stress drop), with a maximum depth-averaged crustal shear-stress drop of 4 MPa. We separately estimate that the plate-driving forces acting in the region, regardless of their exact mechanism, must contribute at least 27 MPa trench-perpendicular compression and 15 MPa trench-parallel compression. This corresponds to a depth-averaged shear stress of at least 7 MPa. The comparable magnitude of these two independent shear stress estimates is consistent with the interpretation that the section of the megathrust fault ruptured in the Maule earthquake is weak, with the seismic cycle relieving much of the total sustained shear stress in the crust. Copyright 2011 by the American Geophysical Union.

Co- and post-seismic shallow fault physics from near-field geodesy, seismic tomography, and mechanical modeling

NASA Astrophysics Data System (ADS)

Nevitt, J.; Brooks, B. A.; Catchings, R.; Goldman, M.; Criley, C.; Chan, J. H.; Glennie, C. L.; Ericksen, T. L.; Madugo, C. M.

2017-12-01

The physics governing near-surface fault slip and deformation are largely unknown, introducing significant uncertainty into seismic hazard models. Here we combine near-field measurements of surface deformation from the 2014 M6.0 South Napa earthquake with high-resolution seismic imaging and finite element models to investigate the effects of rupture speed, elastic heterogeneities, and plasticity on shallow faulting. We focus on two sites that experienced either predominantly co-seismic or post-seismic slip. We measured surface deformation with mobile laser scanning of deformed vine rows within 300 m of the fault at 1 week and 1 month after the event. Shear strain profiles for the co- and post-seismic sites are similar, with maxima of 0.012 and 0.013 and values exceeding 0.002 occurring within 26 m- and 18 m-wide zones, respectively. That the rupture remained buried at the two sites and produced similar deformation fields suggests that permanent deformation due to dynamic stresses did not differ significantly from the quasi-static case, which might be expected if the rupture decelerated as it approached the surface. Active-source seismic surveys, 120 m in length with 1 m geophone/shot spacing, reveal shallow compliant zones of reduced shear modulus. For the co- and post-seismic sites, the tomographic anomaly (Vp/Vs > 5) at 20 m depth has a width of 80 m and 50 m, respectively, much wider than the observed surface displacement fields. We investigate this discrepancy with a suite of finite element models in which a planar fault is buried 5 m below the surface. The model continuum is defined by either homogeneous or heterogeneous elastic properties, with or without Drucker-Prager plastic yielding, with properties derived from lab testing of similar near-surface materials. We find that plastic yielding can greatly narrow the surface displacement zone, but that the width of this zone is largely insensitive to changes in the elastic structure (i.e., the presence of a compliant zone).

On the potential of a new IVUS elasticity modulus imaging approach for detecting vulnerable atherosclerotic coronary plaques: In vitro vessel phantom study

PubMed Central

Le Floc’h, Simon; Cloutier, Guy; Finet, Gérard; Tracqui, Philippe; Pettigrew, Roderic I.; Ohayon, Jacques

2016-01-01

Peak cap stress amplitude is recognized as a good indicator of vulnerable plaque (VP) rupture. However, such stress evaluation strongly relies on a precise, but still lacking, knowledge of the mechanical properties exhibited by the plaque components. As a first response to this limitation, our group recently developed, in a previous theoretical study, an original approach, called iMOD, which reconstructs elasticity maps (or modulograms) of atheroma plaques from the estimation of strain fields. In the present in vitro experimental study, conducted on PVA-C arterial phantoms, we investigate the benefit of coupling the iMOD procedure with the acquisition of intravascular ultrasound (IVUS) measurements for detection of VP. Our results show that the combined iMOD-IVUS strategy : 1) successfully detected and quantified soft inclusion contours with high positive predictive values and sensitivities of 89.7 ± 3.9% and 81.5 ± 8.8 %, respectively, 2) estimated reasonably cap thicknesses larger than ~300 µm, but underestimated thinner caps, and 3) quantified satisfactorily Young's modulus of hard medium (mean value of 109.7 ± 23.7 kPa instead of 145.4 ± 31.8 kPa), but overestimated the stiffness of soft inclusions (mean Young`s moduli of 31.4 ± 9.7 kPa instead of 17.6 ± 3.4 kPa). All together, these results demonstrate a promising benefit of the new iMOD-IVUS clinical imaging method for in vivo VP detection. PMID:20826899

Effects of cryogenic thermal cycle and immersion on the mechanical characteristics of phenol-resin bonded plywood

NASA Astrophysics Data System (ADS)

Kim, Jeong-Hyeon; Park, Doo-Hwan; Lee, Chi-Seung; Park, Kwang-Jun; Lee, Jae-Myung

2015-12-01

The main objective of the present study is to investigate the performance degradation of the plywood used in a liquefied natural gas (LNG) cargo containment system (CCS). A plywood sheet features an odd number of thinly layered wooden plies bonded perpendicularly to the previous layer to give it a very strong and durable structure. Owing to this strong point, plywood is applied to a variety of interior and exterior applications. Above all, it is widely adopted as insulation panels in an LNG CCS owing to a high stiffness with low density and its superior mechanical capabilities. As an insulation material of an LNG CCS, plywood is constantly exposed to repeated wave-induced thermal variations caused by the loading (-163 °C) and unloading (20 °C) of LNG during general operating periods of 25 years on average. Therefore, the effects of cryogenic-level thermal loads on the material characteristics of plywood must be analyzed with respect to the design and safety aspects of LNG CCSs. In the present study, the influences of the estimated thermal load, testing temperature, and grain orientation on plywood adopted in an LNG CCS are investigated. In terms of safety and design, the repeated thermal loads in a LNG CCS must be considered because the modulus of elasticity (MOE), tensile strength (TS), and modulus of rupture (MOR) are degraded by thermal treatments, such as cyclic thermal-shock and cryogenic immersion.

Preliminary investigation on the suitablity of using fiber reinforced concrete in the construction of a hazardous waste disposal vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramey, M.R.; Daie-e, G.

1988-07-01

There are certain hazardous wastes that must be contained in an extremely secure vessel for transportation and disposal. The vessel, among other things, must be able to withstand relatively large impacts without rupturing. Such containment vessels therefore must be able to absorb substantial amounts of energy during an impact and still perform their function. One of the impacts that the vessel must withstand is a 30-foot fall onto an unyielding surface. For some disposal scenarios it is proposed to encase the waste in a steel enclosure which is to be surrounded by a thick layer of concrete which, in turn,more » is encased by a relatively thin steel shell. Tests on concrete in compression and flexure, including static, dynamic and impact tests, have shown that low modulus concretes tend to behave in a less brittle manner than higher modulus concretes. Tests also show that fiber reinforced concretes have significantly greater ductility, crack propagation resistance and toughness than conventional concretes. Since it is known that concrete is a reasonably brittle material, it is necessary to do impact tests on sample containment structures consisting of thin-walled metal containers having closed ends which are filled with concrete, grout, or fiber reinforced concrete. This report presents the results of simple tests aimed at observing the behavior of sample containment structures subjected to impacts due to a fall from 30 feet. 8 figs., 4 tabs.« less

Complex Channel Avulsion in the Meghna River Foodplain During the Mid to Late Holocene: The Potential Effect of Tectonic and Co-Seismic Uplift

NASA Astrophysics Data System (ADS)

Dunham, A.; Grall, C.; Mondal, D. R.; Steckler, M. S.; Rajapara, H.; Kumar, B.; Philibosian, B.; Akhter, S. H.; Singhvi, A. K.

2016-12-01

Channel migrations and river avulsions in deltaic river systems are mainly driven by differential changes of surface topography, such as the superelevation of channels due to sedimentation. In addition to such autocyclic processes, tectonic events, such as earthquakes, may also lead to avulsions from sudden uplift. The eastern part of the Ganges-Brahmaputra-Meghna Delta (GBMD) is underlain by the blind megathrust of the IndoBurma subduction zone. In this region we investigate a 100 km long sinuous abandoned channel of the Meghna River. Immediately south of the channel, it has been previously shown that the topography is slightly higher than on the rest of the Delta and there is an oxidized Holocene exposure surface. Part of the Titas River flows northward from this area into the abandoned channel belt, opposite of the southward flowing rivers of the delta. We provide results from a detailed investigation of this abandoned channel of the Meghna River using stratigraphic logs of hand-drilled wells, resistivity profiles, sediment analyses and OSL and C14 dating, The OSL ages to be presented constrain the possible date of the event. We employ numerical modeling to evaluate the hypothesis that the co-seismic uplift associated to an earthquake can trigger the channel migration. Our modeling approach aims to estimate the co-seismic uplift associated with potential seismic events using an elastic Coulomb's dislocation model. The geometry fault in our model is estimated using geologic and GPS constraints with standard elastic parameters (Young's modulus = 80 GPa; Poisson's ratio = 0.3). We explored different potential earthquakes geometries that involve the megathrust, a splay fault, or the megathrust terminating in the splay. The magnitude and distribution of co-seismic slip are also varied between a rupture length of 112.5km and 180km along a 225km long fault. We show that any class of models can produce the amount of uplift (1-2 m) necessary for triggering the river avulsion. Thus the avulsion could be due to a >M8 megathrust earthquake or a M7 splay fault rupture. In either case, the rupture cannot extend west of the abandoned channel to the current Meghna River, and thus did not rupture to the deformation front, where the megacity of Dhaka now lies.

Mechanical properties and fibrin characteristics of endovascular coil–clot complexes: relevance to endovascular cerebral aneurysm repair paradigms

PubMed Central

Haworth, Kevin J; Weidner, Christopher R; Abruzzo, Todd A; Shearn, Jason T; Holland, Christy K

2015-01-01

Background Although coil embolization is known to prevent rebleeding from acutely ruptured cerebral aneurysms, the underlying biological and mechanical mechanisms have not been characterized. We sought to determine if microcoil-dependent interactions with thrombus induce structural and mechanical changes in the adjacent fibrin network. Such changes could play an important role in the prevention of aneurysm rebleeding. Methods The stiffness of in vitro human blood clots and coil–clot complexes implanted into aneurysm phantoms were measured immediately after formation and after retraction for 3 days using unconfined uniaxial compression assays. Scanning electron microscopy of the coil–clot complexes showed the effect of coiling on clot structure. Results The coil packing densities achieved were in the range of clinical practice. Bare platinum coils increased clot stiffness relative to clot alone (Young’s modulus 6.9 kPa and 0.83 kPa, respectively) but did not affect fibrin structure. Hydrogel-coated coils prevented formation of a clot and had no significant effect on clot stiffness (Young’s modulus 2 kPa) relative to clot alone. Clot age decreased fiber density by 0.2 fibers/µm2 but not the stiffness of the bare platinum coil–clot complex. Conclusions The stiffness of coil–clot complexes is related to the summative stiffness of the fibrin network and associated microcoils. Hydrogel-coated coils exhibit significantly less stiffness due to the mechanical properties of the hydrogel and the inhibition of fibrin network formation by the hydrogel. These findings have important implications for the design and engineering of aneurysm occlusion devices. PMID:24668257

Quantitative US Elastography Can Be Used to Quantify Mechanical and Histologic Tendon Healing in a Rabbit Model of Achilles Tendon Transection.

PubMed

Yamamoto, Yohei; Yamaguchi, Satoshi; Sasho, Takahisa; Fukawa, Taisuke; Akatsu, Yorikazu; Akagi, Ryuichiro; Yamaguchi, Tadashi; Takahashi, Kenji; Nagashima, Kengo; Takahashi, Kazuhisa

2017-05-01

Purpose To determine the time-dependent change in strain ratios (SRs) at the healing site of an Achilles tendon rupture in a rabbit model of tendon transection and to assess the correlation between SRs and the mechanical and histologic properties of the healing tissue. Materials and Methods Experimental methods were approved by the institutional animal care and use committee. The Achilles tendons of 24 New Zealand white rabbits (48 limbs) were surgically transected. The SRs of Achilles tendons were calculated by using compression-based quantitative ultrasonographic elastography measurements obtained 2, 4, 8, and 12 weeks after transection. After in vivo elastography, the left Achilles tendon was harvested for mechanical testing of ultimate load, ultimate stress, elastic modulus, and linear stiffness, and the right tendons were harvested for tissue histologic analysis with the Bonar scale. Time-dependent changes in SRs, mechanical parameters, and Bonar scale scores were evaluated by using repeated-measures analysis of variance. The correlation between SRs and each measured variable was evaluated by using the Spearman rank correlation coefficient. Results Mean SRs and Bonar scale values decreased as a function of time after transection, whereas mechanical parameters increased (P < .001). SR correlated with ultimate stress (ρ = 0.68, P <.001,) elastic modulus (ρ = 0.74, P <.001), and the Bonar scale (ρ = 0.87, P <.001). Conclusion Quantitative elastography could be a useful method with which to evaluate mechanical and histologic properties of the healing tendon. © RSNA, 2017 Online supplemental material is available for this article.

Regional stiffening with aging in tibialis anterior tendons of mice occurs independent of changes in collagen fibril morphology

PubMed Central

Wood, Lauren K.; Arruda, Ellen M.

2011-01-01

The incidence of tendon degeneration and rupture increases with advancing age. The mechanisms underlying this increased risk remain unknown but may arise because of age-related changes in tendon mechanical properties and structure. Our purpose was to determine the effect of aging on tendon mechanical properties and collagen fibril morphology. Regional mechanical properties and collagen fibril characteristics were determined along the length of tibialis anterior (TA) tendons from adult (8- to 12-mo-old) and old (28- to 30-mo-old) mice. Tangent modulus of all regions along the tendons increased in old age, but the increase was substantially greater in the proximal region adjacent to the muscle than in the rest of the tendon. Overall end-to-end modulus increased with old age at maximum tendon strain (799 ± 157 vs. 1,419 ± 91 MPa) and at physiologically relevant strain (377 ± 137 vs. 798 ± 104 MPa). Despite the dramatic changes in tendon mechanical properties from adulthood to old age, collagen fibril morphology and packing fraction remained relatively constant in all tendon regions examined. Since tendon properties are influenced by their external loading environment, we also examined the effect of aging on TA muscle contractile properties. Maximum isometric force did not differ between the age groups. We conclude that TA tendons stiffen in a region-dependent manner throughout the life span, but the changes in mechanical properties are not accompanied by corresponding changes in collagen fibril morphology or force-generating capacity of the TA muscle. PMID:21737825

Fabrication and characterisation of phantom material made of Tannin-added Rhizophora spp. particleboards for photon and electron beams

NASA Astrophysics Data System (ADS)

Yusof, M. F. Mohd; Hamid, P. N. K. Abd; Tajuddin, A. A.; Hashim, R.; Bauk, S.; Isa, N. Mohd; Isa, M. J. Md

2017-05-01

Particleboards made of Rhizophora spp. with addition of tannin adhesive were fabricated at target density of 1.0 g/cm3. The physical and mechanical properties of the particleboards including internal bond strength (IB) and modulus of rupture (MOR) were measured based on Japanese Industrial Standards (JIS A-5908). The characterisation of the particleboards including the effective atomic number, CT number and relative electron density were determined and compared to water. The mass attenuation coefficient of the particleboards were measured and compared to the calculated value of water using photon cross-section database (XCOM). The results showed that the physical and mechanical properties of the particleboards complied with Type 13 and 18 of JIS A-5908. The values of effective atomic number, CT number and relative electron density were also close to the value of water. The value of mass attenuation coefficients of the particleboards showed good agreement with water (XCOM) at low and high energy photon indicated by the χ2 values.

Utilization of Electric Arc Furnace Dust as raw material for the production of ceramic and concrete building products.

PubMed

Sikalidis, Constantine; Mitrakas, Manassis

2006-01-01

The up to 20 wt% addition of the Electric Arc Furnace Dust (EAFD) hazardous waste on the properties of extruded clay-based ceramic building products fired at various temperatures (850 to 1050 degrees C), as well as of dolomite-concrete products was investigated. Chemical, mineralogical and particle size distribution analyses were performed in order to characterize the used EAFD. The results showed that the ceramic specimens prepared had water absorption, firing shrinkage, apparent density, mechanical strength, colour and leaching behaviour within accepted limits. Addition of 7.5 to 15 wt% EAFD presented improved properties, while 20 wt% seems to be the upper limit. Dolomite-concrete specimens were prepared by vibration and press-forming of mixtures containing cement, sand, dolomite, EAFD and water. Modulus of rupture values were significantly increased by the addition of EAFD. The leaching tests showed stabilization of all toxic metals within the sintered ceramic structure, while the leaching behaviour of lead in dolomite-concrete products needs further detailed study.

Transformation toughened ceramics for the heavy duty diesel engine technology program, phase 2

NASA Technical Reports Server (NTRS)

Musikant, S.; Samanta, S. C.; Architetto, P.; Feingold, E.

1985-01-01

The objective of this program is to develop an insulating structural ceramic for application in a heavy duty adiabatic diesel engine. The approach is to employ transformation toughening (TT) by additions of zirconia-hafnia solid solution (ZHSS). The feasibility of using ZHSS as a toughening agent in mullite and alumina has been demonstrated in Phase 1 of this work. Based on Phase 1 results, a decision was made to concentrate the Phase 2 effort on process optimization of the TT mullite. A strong factor in that decision was the low thermal conductivity and high thermal shock resistance of the mullite. Results of the Phase 2 effort indicate that optimum toughening of mullite by additions of ZHSS is difficult to achieve due to apparent sensitivity to morphology. The 48 ksi room temperature modulus-of-rupture (MOR) achieved in selected specimens is approximately 50% of the original strength target. The MOR deteriorated to 34 ksi at 800 C.

Effect of grain orientation and coating on thermal fatigue resistance of a directionally solidified superalloy (MAR-M 247)

NASA Technical Reports Server (NTRS)

Bizon, P. T.; Dreshfield, R. L.; Calfo, F. D.

1979-01-01

The effect of off-axis directionally solidified (DS) grain growth on thermal fatigue life of Mar-M 247 alloy was evaluated. Uncoated conventionally cast as well as DS wedge bars were cycled in a burner rig between 1070 C and room temperature. The longitudinal axis and leading edge of the specimen coincided. As the angle between the specimen longitudinal axis and growth axis increased, the thermal fatigue life decreased for both the uncoated and aluminide-coated bars. Life increases of about 50 cycles for the DS conditions were attributed to coating. The decrease in thermal fatigue life with increasing angle is primarily attributed to the increase in modulus of elasticity with increasing angle and not to the intersection of DS grain boundaries with the specimen leading edge. The thermal fatigue cracks were observed to be transgranular in the DS material. Limited tensile and stress-rupture properties of conventionally cast and off-axis DS Mar-M 247 alloy are also presented.

Development and evaluation of tetrapod-shaped granular artificial bones.

PubMed

Choi, Sungjin; Liu, I-li; Yamamoto, Kenichi; Igawa, Kazuyo; Mochizuki, Manabu; Sakai, Takamasa; Echigo, Ryosuke; Honnami, Muneki; Suzuki, Shigeki; Chung, Ung-il; Sasaki, Nobuo

2012-07-01

We have developed a novel form of granular artificial bone "Tetrabones" with a homogeneous tetrapod shape and uniform size. Tetrabones are four armed structures that accumulate to form the intergranular pores that allow invasion of cells and blood vessels. In this study we evaluated the physicochemical characteristics of Tetrabones in vitro, and compared their biological and biomechanical properties in vivo to those of conventional β-tricalcium phosphate (β-TCP) granule artificial bone. Both the rupture strength and elastic modulus of Tetrabone particles were higher than those of β-TCP granules in vitro. The connectivity of intergranular pores 100, 300, and 400 μm in size were higher in Tetrabones than in the β-TCP granules. Tetrabones showed similar osteoconductivity and biomechanical stiffness to β-TCP at 2 months after implantation in an in vivo study of canine bone defects. These results suggest that Tetrabones may be a good bone graft material in bone reconstruction. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Transformation toughened ceramics for the heavy duty diesel engine technology program

NASA Technical Reports Server (NTRS)

Musikant, S.; Feingold, E.; Rauch, H.; Samanta, S.

1984-01-01

The objective of this program is to develop an advanced high temperature oxide structural ceramic for application to the heavy duty diesel engine. The approach is to employ transformation toughening by additions of ZrO.5HfO.5O2 solid solution to the oxide ceramics, mullite (2Al2O3S2SiO2) and alumina (Al2O3). The study is planned for three phases, each 12 months in duration. This report covers Phase 1. During this period, processing techniques were developed to incorporate the ZrO.5HfO.5O2 solid solution in the matrices while retaining the necessary metastable tetragonal phase. Modulus of rupture and of elasticity, coefficient of thermal expansion, fracture toughness by indent technique and thermal diffusivity of representative specimens were measured. In Phase 2, the process will be improved to provide higher mechanical strength and to define the techniques for scale up to component size. In Phase 3, full scale component prototypes will be fabri-]cated.

Influence of airway wall compliance on epithelial cell injury and adhesion during interfacial flows

PubMed Central

Higuita-Castro, Natalia; Mihai, Cosmin; Hansford, Derek J.

2014-01-01

Interfacial flows during cyclic airway reopening are an important source of ventilator-induced lung injury. However, it is not known how changes in airway wall compliance influence cell injury during airway reopening. We used an in vitro model of airway reopening in a compliant microchannel to investigate how airway wall stiffness influences epithelial cell injury. Epithelial cells were grown on gel substrates with different rigidities, and cellular responses to substrate stiffness were evaluated in terms of metabolic activity, mechanics, morphology, and adhesion. Repeated microbubble propagations were used to simulate cyclic airway reopening, and cell injury and detachment were quantified via live/dead staining. Although cells cultured on softer gels exhibited a reduced elastic modulus, these cells experienced less plasma membrane rupture/necrosis. Cells on rigid gels exhibited a minor, but statistically significant, increase in the power law exponent and also exhibited a significantly larger height-to-length aspect ratio. Previous studies indicate that this change in morphology amplifies interfacial stresses and, therefore, correlates with the increased necrosis observed during airway reopening. Although cells cultured on stiff substrates exhibited more plasma membrane rupture, these cells experienced significantly less detachment and monolayer disruption during airway reopening. Western blotting and immunofluorescence indicate that this protection from detachment and monolayer disruption correlates with increased focal adhesion kinase and phosphorylated paxillin expression. Therefore, changes in cell morphology and focal adhesion structure may govern injury responses during compliant airway reopening. In addition, these results indicate that changes in airway compliance, as occurs during fibrosis or emphysema, may significantly influence cell injury during mechanical ventilation. PMID:25213636

Refractory Materials for Flame Deflector Protection

NASA Technical Reports Server (NTRS)

Calle, Luz M.; Hintze, Paul E.; Parlier, Christopher R.; Sampson, Jeffrey W.; Curran, Jerome P.; Kolody, Mark R.; Peruisich, Stephen A.

2010-01-01

Fondu Fyre (FF) is currently the only refractory material qualified for use in the flame trench at KSC's Shuttle Launch Pads 39A and 3913. However, the material is not used as it was qualified and has undergone increasingly frequent and severe degradation due to the launch blasts. This degradation is costly as well as dangerous for launch infrastructure, crew and vehicle. The launch environment at KSC is unique. The refractory material is subject to the normal seacoast environment, is completely saturated with water before launch, and is subjected to vibrations and aggressive heat/blast conditions during launch. This report presents results comparing two alternate materials, Ultra-Tek FS gun mix and Kruzite GR Plus, with Fondu Fyre. The materials were subjected to bulk density, porosity, compression strength, modulus of rupture and thermal shock tests. In addition, test specimens were exposed to conditions meant to simulate the launch environment at KSC to help better understand how the materials will perform once installed.

Co-seismic Static Stress Drops for Earthquake Ruptures Nucleated on Faults After Progressive Strain Localization

NASA Astrophysics Data System (ADS)

Griffith, W. A.; Nielsen, S.; di Toro, G.; Pollard, D. D.; Pennacchioni, G.

2007-12-01

We estimate the coseismic static stress drop on small exhumed strike-slip faults in the Mt. Abbot quadrangle of the central Sierra Nevada (California). The sub-vertical strike-slip faults cut ~85 Ma granodiorite, were exhumed from 7-10 km depth, and were chosen because they are exposed along their entire lengths, ranging from 8 to 13 m. Net slip is estimated using offset aplite dikes and shallowly plunging slickenlines on the fault surfaces. The faults show a record of progressive strain localization: slip initially nucleated on joints and accumulated from ductile shearing (quartz-bearing mylonites) to brittle slipping (epidote-bearing cataclasites). Thin (< 1 mm) pseudotachylytes associated with the cataclasites have been identified along some faults, suggesting that brittle slip may have been seismic. The brittle contribution to slip may be distinguished from the ductile shearing because epidote-filled, rhombohedral dilational jogs opened at bends and step-overs during brittle slip, are distributed periodically along the length of the faults. We argue that brittle slip occurred along the measured fault lengths in single slip events based on several pieces of evidence. 1) Epidote crystals are randomly oriented and undeformed within dilational jogs, indicating they did not grow during aseismic slip and were not broken after initial opening and precipitation. 2) Opening-mode splay cracks are concentrated near fault tips rather than the fault center, suggesting that the reactivated faults ruptured all at once rather than in smaller slip patches. 3) The fact that the opening lengths of the dilational jogs vary systematically along the fault traces suggests that brittle reactivation occurred in a single slip event along the entire fault rather than in multiple slip events. This unique combination of factors distinguishes this study from previous attempts to estimate stress drop from exhumed faults because we can constrain the coseismic rupture length and slip. The static stress drop is calculated for a circular fault using the length of the mapped faults and their slip distributions as well as the shear modulus of the host granodiorite measured in the laboratory. Calculations yield stress drops on the order of 100-200 MPa, one to two orders of magnitude larger than typical seismological estimates. The studied seismic ruptures occurred along small, deep-seated faults (10 km depth), and, given the fault mineral filling (quartz-bearing mylonites) these were "strong" faults. Our estimates are consistent with static stress drops estimated by Nadeau and Johnson (1998) for small repeated earthquakes.

Physical, mechanical and electrochemical characterization of all-perovskite intermediate temperature solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Mohammadi, Alidad

Strontium- and magnesium-doped lanthanum gallate (LSGM) has been considered as a promising electrolyte for solid oxide fuel cell (SOFC) systems in recent years due to its high ionic conductivity and chemical stability over a wide range of oxygen partial pressures and temperatures. This research describes synthesis, physical and mechanical behavior, electrochemical properties, phase evolution, and microstructure of components of an all-perovskite anode-supported intermediate temperature solid oxide fuel cell (ITSOFC), based on porous La 0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) anode, La0.8Sr0.2Ga0.8Mg0.2O 2.8 (LSGM) electrolyte, and porous La0.6Sr0.4Fe 0.8Co0.2O3 (LSCF) cathode. The phase evolution of synthesized LSGM and LSCM powders has been investigated, and it has been confirmed that there is no reaction between LSGM and LSCM at sintering temperature. Using different amounts of poreformers and binders as well as controlling firing temperature, porosity of the anode was optimized while still retaining good mechanical integrity. The effect of cell operation conditions under dry hydrogen fuel on the SOFC open circuit voltage (OCV) and cell performance were also investigated. Characterization study of the synthesized LSGM indicates that sintering at 1500°C obtains higher electrical conductivity compared to the currently published results, while conductivity of pellets sintered at 1400°C and 1450°C would be slightly lower. The effect of sintering temperature on bulk and grain boundary resistivities was also discussed. The mechanical properties, such as hardness, Young's modulus, fracture toughness and modulus of rupture of the electrolyte were determined and correlated with scanning electron microscopy (SEM) morphological characterization. Linear thermal expansion and thermal expansion coefficient of LSGM were also measured.

Physical and mechanical properties of parallel strand lumber made from hot pre-pressed long strand oil palm trunk waste

NASA Astrophysics Data System (ADS)

Fridiyanti, Inayah; Massijaya, M. Y.

2018-03-01

This research was focused on the utilization of oil palm trunk waste as a Parallel Strand Lumber (PSL) raw material. This research aimed to analyze the effect of adhesive types and glue spreads to the physical and mechanical properties of PSL. The adhesive types used were isocyanate and urea formaldehyde adhesives. The glue spreads used were 150 g/m2 and 300 g/m2. The research results showed that the moisture content of PSL ranged from 9.30% to 11.80%. The PSL density ranged from 0.64 to 0.78 g/cm3. The volume shrinkage ranged from 5.69 to 7.17%. Modulus of Elasticity (MOE) parallel to the grain and edge side ranged from 51.6 × 103 to 98.3 × 103 kg/cm2, and 62.1 × 103 to 99.9 × 103 kg/cm2, respectively. The Modulus of Rupture (MOR) parallel to the grain and edge side ranged from 269 to 724 kg/cm2 and 342 to 728 kg/cm2, respectively. The PSL hardness perpendicular to the grain, parallel to the grain and the edge side ranged from 135 to 300 kg/cm2, 87 to 321 kg/cm2, and 128 to 251 kg/cm2, respectively. The compressive strength ranged from 181 to 231 kg/cm2. The best adhesive and glue spreads of PSL was isocyanate with glue spread 300 g/m2. PSL made from hot pre-pressed long strand of oil palm trunk waste bonded by isocyanate fulfill JAS 1152: 2007. However, those of bonded by urea formaldehyde failed to fulfill the standard. The physical and mechanical properties of PSL made from oil palm trunk were better compared to those of solid oil palm trunk.

A comprehensive investigation of mechanical and acoustic modifications in wood treated with high doses of gamma radiation for sterilization

NASA Astrophysics Data System (ADS)

Ricci, G.; Regazzi, R.; Tositti, L.; Barbaresi, L.; Liverani, A.; Mostacci, D.

2016-09-01

Gamma radiation is a most efficient tool for sterilization, and especially effective on infesting pest, as it also kills the eggs. However, the large radiation doses entailed (tens of kilogray and up) might have adverse effects on desirable properties of wood. Of particular interest are the acoustic properties, as radiation would otherwise appear to be the perfect tool for the sterilization of musical instruments. The present investigation was aimed at determining the effects on acoustic and mechanical properties. Samples of four different wood species - poplar, oak, fir and maple - were prepared selecting wood completely free of visually detectable defects and subjected to incremental dose levels, reaching 25, 50, 100 and 200 kGy. A further set of samples were subjected to 200 kGy in one go, to investigate possible differences with incremental doses. Irradiation was conducted at an industrial irradiation facility, operating with a cobalt-60 source of the order of the megacurie. The mechanical tests were designed to measure the elastic modulus and the bending strength as well as force and displacement at rupture. Acoustic tests were developed specifically for this experiment, with the purpose of measuring the vibrational modes of the samples. All the samples exhibited discoloration and noticeable changes in properties: rigidity increased, load to rupture decreased, the material became more brittle and effects increased with increasing dose. The acoustic tests revealed a shift toward higher frequencies of all the vibrational modes, and this was exhibited for all wood species investigated. No meaningful difference was observed between the samples treated with incremental doses up to a total of 200 kGy and with a single 200 kGy dose.

Improved silicon carbide for advanced heat engines

NASA Technical Reports Server (NTRS)

Whalen, Thomas J.; Mangels, J. A.

1986-01-01

The development of silicon carbide materials of high strength was initiated and components of complex shape and high reliability were formed. The approach was to adapt a beta-SiC powder and binder system to the injection molding process and to develop procedures and process parameters capable of providing a sintered silicon carbide material with improved properties. The initial effort was to characterize the baseline precursor materials, develop mixing and injection molding procedures for fabricating test bars, and characterize the properties of the sintered materials. Parallel studies of various mixing, dewaxing, and sintering procedures were performed in order to distinguish process routes for improving material properties. A total of 276 modulus-of-rupture (MOR) bars of the baseline material was molded, and 122 bars were fully processed to a sinter density of approximately 95 percent. Fluid mixing techniques were developed which significantly reduced flaw size and improved the strength of the material. Initial MOR tests indicated that strength of the fluid-mixed material exceeds the baseline property by more than 33 percent. the baseline property by more than 33 percent.

Effects of spent mushroom compost application on the physicochemical properties of a degraded soil

NASA Astrophysics Data System (ADS)

Gümüş, İlknur; Şeker, Cevdet

2017-11-01

Under field and laboratory conditions, the application of organic amendments has generally shown an improvement in soil physicochemical properties. Here, spent mushroom compost (SMC) is proposed as a suitable organic amendment for soil structure restoration. Our study assessed the impact of SMC on the physicochemical properties of a weak-structured and physically degraded soil. The approach involved the establishment of a pot experiment with SMC applications into soil (control, 0.5, 1, 2, 4 and 8 %). Soils were incubated at field capacity (-33 kPa) for 21, 42, and 62 days under laboratory conditions. SMC applications into the soil significantly increased the aggregate stability (AS) and decreased the modulus of rupture. The application of SMC at rates of 1, 2, 4, and 8 % significantly increased the total nitrogen and soil organic carbon contents of the degraded soil at all incubation periods (p < 0.05). The results obtained in this study indicate that the application of SMC can improve soil physicochemical properties, which may benefit farmers, land managers, and mushroom growers.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rao, S.M.; Brinkar, C.J.; Rao, S.M.

We are testing an anti-weathering preservation strategy that is specific to limestone surfaces. The strategy involves the application of a mineral-specific, bifunctional, passivating/coupling agent that binds to both the limestone surface and to the consolidating inorganic polymer matrix. The sol-gel based reactions form composite materials with desirable conservation and anti-weathering properties. We present the results of our efforts, the highlights of which are: (1) scanning probe microscopy of moisture-free calcite crystals treated with the trisilanol form of silylalkylaminocarboxylate (SAAC), reveals porous agglomerates that offer no significant resistance to the mild leaching action of deionized water. When the crystals are furthermore » consolidated with a silica-based consolidant (A2**), no dissolution is seen although the positive role of the passivant molecule is not yet delineated. (2) Modulus of rupture tests on limestone cores treated with an aminoalkylsilane (AEAPS) and A2** showed a 25-35% increase in strength compared to the untreated samples. (3) Environmental scanning electron microscopy of treated limestone subjected to a concentrated acid attack showed degradation of the surface except in areas where thick layers of the consolidant were deposited.« less

Pressureless sintered beta prime-Si3N4 solid solution: Fabrication, microstructure, and strength

NASA Technical Reports Server (NTRS)

Dutta, S.

1977-01-01

Si3N4, AlN, and Al2O3 were used as basic constituents in a study of the pressureless sintering of beta prime-Si3N4 solid solution as a function of temperature. Y2O3-SiO2 additions were used to promote liquid-phase sintering. The sintered specimens were characterized with respect to density, microstructure, strength, oxidation, and thermal shock resistance. Density greater than 98 percent of theoretical was achieved by pressureless sintering at 1750 C. The microstructure consisted essentially of fine-grained beta prime-Si3N4 solid solution as the major phase. Modulus of rupture strengths up to 483 MPa were achieved at moderate temperature (1000 C), but decreased to 228 MPa at 1380 C. This substantial strength loss was attributed to a glassy grain boundary phase formed during cooling from the sintering temperature. The best oxidation resistance was exhibited by a composition containing 3 mol % Y2O3-SiO2 additives. Water quench thermal shock resistance was equivalent to that of reaction sintered silicon nitride but lower than hot-pressed silicon nitride.

Biodegradable and Elastomeric Poly(glycerol sebacate) as a Coating Material for Nitinol Bare Stent

PubMed Central

Kim, Min Ji; Hwang, Moon Young; Kim, JiHeung; Chung, Dong June

2014-01-01

We synthesized and evaluated biodegradable and elastomeric polyesters (poly(glycerol sebacate) (PGS)) using polycondensation between glycerol and sebacic acid to form a cross-linked network structure without using exogenous catalysts. Synthesized materials possess good mechanical properties, elasticity, and surface erosion biodegradation behavior. The tensile strength of the PGS was as high as 0.28 ± 0.004 MPa, and Young's modulus was 0.122 ± 0.0003 MPa. Elongation was as high as 237.8 ± 0.64%, and repeated elongation behavior was also observed to at least three times the original length without rupture. The water-in-air contact angles of the PGS surfaces were about 60°. We also analyzed the properties of an electrospray coating of biodegradable PGS on a nitinol stent for the purpose of enhancing long-term patency for the therapeutic treatment of varicose veins disease. The surface morphology and thickness of coating layer could be controlled by adjusting the electrospraying conditions and solution parameters. PMID:24955369

Development of dense glass-ceramic from recycled soda-lime-silicate glass and fly ash for tiling

NASA Astrophysics Data System (ADS)

Mustaffar, Mohd Idham; Mahmud, Mohamad Haniza; Hassan, Mahadi Abu

2017-12-01

Dense glass-ceramics were prepared by sinter-crystallization process from a combination of soda-lime-silicate glass waste and fly ash. Bentonite clay that acted as a binder was also added in a prepared formulation. The powder mixture of soda-lime glass, fly ash and bentonite clay were compacted by using uniaxial hydraulic press machine and sintered at six (6) various temperatures namely 750, 800, 850, 900, 950 and 1000 °C. The heating rate and sintering time were set at 5 °C/min and 30 minutes respectively. The results revealed that modulus of rupture (MOR), density and linear shrinkage increase first from 750 to 800 °C but decrease later after 800 to 1000 °C. In the meantime, water absorption was showing completely an opposite trend. The glass-ceramic sintered at 800 °C was found to have the best combination of physical-mechanical properties and has the potential to be applied in the construction industry particularly as floor and wall tiles because of the simple manufacturing process at low temperature.

SCARE: A post-processor program to MSC/NASTRAN for the reliability analysis of structural ceramic components

NASA Technical Reports Server (NTRS)

Gyekenyesi, J. P.

1985-01-01

A computer program was developed for calculating the statistical fast fracture reliability and failure probability of ceramic components. The program includes the two-parameter Weibull material fracture strength distribution model, using the principle of independent action for polyaxial stress states and Batdorf's shear-sensitive as well as shear-insensitive crack theories, all for volume distributed flaws in macroscopically isotropic solids. Both penny-shaped cracks and Griffith cracks are included in the Batdorf shear-sensitive crack response calculations, using Griffith's maximum tensile stress or critical coplanar strain energy release rate criteria to predict mixed mode fracture. Weibull material parameters can also be calculated from modulus of rupture bar tests, using the least squares method with known specimen geometry and fracture data. The reliability prediction analysis uses MSC/NASTRAN stress, temperature and volume output, obtained from the use of three-dimensional, quadratic, isoparametric, or axisymmetric finite elements. The statistical fast fracture theories employed, along with selected input and output formats and options, are summarized. An example problem to demonstrate various features of the program is included.

Dynamics of a fluid-driven crack in three dimensions by the finite difference method

NASA Astrophysics Data System (ADS)

Chouet, Bernard

1986-12-01

The finite difference method is applied to the study of the dynamics of a three-dimensional fluid-filled crack excited into resonance by the sudden failure of a small barrier of area ΔS on the crack surface. The impulse response of the crack is examined for various ratios of crack width to crack length and for several values of the crack stiffness C = (b/μ)(L/d), where b is the bulk modulus of the fluid, μ is the rigidity of the solid, and L and d are the crack length and crack thickness, respectively. The motion of the crack is characterized by distinct time scales representing the duration of brittle failure and the periods of acoustic resonance in the lateral and longitudinal dimensions of the source. The rupture has a duration proportional to the area of crack expansion and is the trigger responsible for the excitation of the crack into resonance; the resonant periods are proportional to the crack stiffness and to the width and length of the crack. The crack wave sustaining the resonance is analogous to the tube wave propagating in a fluid-filled borehole. It is dispersive, showing a phase velocity that decreases with increasing wavelength. Its wave speed is always lower than the acoustic velocity of the fluid and shows a strong dependence on the crack stiffness, decreasing as the stiffness increases. The initial motion of the crack surface is an opening, and the radiated far-field compressional wave starts with a strong but brief compression which has a duration proportional to the crack stiffness and size of the rupture area; the amplitude of this pulse increases with the area of rupture but decreases with increasing stiffness. Flow into the newly created cavity triggers a pressure drop in the fluid, which produces a partial collapse of the wall propagated over the crack surface at the speed of the crack wave. The collapse of the crack surface generates a weak long-period component of dilatation following the compressional first motion in the far-field P wave train; the dilatational component is clearer in the signal from stiffer cracks when seen in the direction of the rupture. The energy loss by radiation is stronger for high frequencies, resulting in a progressive enrichment of the crack response in lower frequencies over the duration of resonance. These source characteristics translate into a far-field signature that is marked by a high-frequency content near its onset and dominated by a longer-period component in its coda. The source duration shows a strong dependence on the fluid viscosity and associated viscous damping at the crack wall.

Determination of the Mechanical Properties of Plasma-Sprayed Hydroxyapatite Coatings Using the Knoop Indentation Technique

NASA Astrophysics Data System (ADS)

Hasan, Md. Fahad; Wang, James; Berndt, Christopher

2015-06-01

The microhardness and elastic modulus of plasma-sprayed hydroxyapatite coatings were evaluated using Knoop indentation on the cross section and on the top surface. The effects of indentation angle, testing direction, measurement location and applied load on the microhardness and elastic modulus were investigated. The variability and distribution of the microhardness and elastic modulus data were statistically analysed using the Weibull modulus distribution. The results indicate that the dependence of microhardness and elastic modulus on the indentation angle exhibits a parabolic shape. Dependence of the microhardness values on the indentation angle follows Pythagoras's theorem. The microhardness, Weibull modulus of microhardness and Weibull modulus of elastic modulus reach their maximum at the central position (175 µm) on the cross section of the coatings. The Weibull modulus of microhardness revealed similar values throughout the thickness, and the Weibull modulus of elastic modulus shows higher values on the top surface compared to the cross section.

Novel Low-Temperature Poss-Containing Siloxane Elastomers

NASA Technical Reports Server (NTRS)

Belcher, Marcus A.; Hinkley, Jeffrey A.; Kiri, Neha N.; Lillehei, Peter T.

2008-01-01

One route to increased aircraft performance is through the use of flexible, shape-changeable aerodynamics effectors. However, state of the art materials are not flexible or durable enough over the required broad temperature range. Mixed siloxanes were crosslinked by polyhedral oligomeric silsesquioxanes (POSS) producing novel materials that remained flexible and elastic from -55 to 94 C. POSS molecules were chemically modified to generate homogeneous distributions within the siloxane matrix. High resolution scanning electron microscope (HRSEM) images indicated homogenous POSS distribution up to 0.8 wt %. Above the solubility limit, POSS aggregates could be seen both macroscopically and via SEM (approx.60-120 nm). Tensile tests were performed to determine Young s modulus, tensile strength, and elongation at break over the range of temperatures associated with transonic aircraft use (-55 to 94 C; -65 to 200 F). The siloxane materials developed here maintained flexibility at -55 C, where previous candidate materials failed. At room temperature, films could be elongated up to 250 % before rupturing. At -55 and 94 C, however, films could be elongated up to 400 % and 125 %, respectively.

Lower crustal relaxation beneath the Tibetan Plateau and Qaidam Basin following the 2001 Kokoxili earthquake

USGS Publications Warehouse

Ryder, I.; Burgmann, R.; Pollitz, F.

2011-01-01

In 2001 November a magnitude 7.8 earthquake ruptured a 400 km long portion of the Kunlun fault, northeastern Tibet. In this study, we analyse over five years of post-seismic geodetic data and interpret the observed surface deformation in terms of stress relaxation in the thick Tibetan lower crust. We model GPS time-series (first year) and InSAR line of sight measurements (years two to five) and infer that the most likely mechanism of post-seismic stress relaxation is time-dependent distributed creep of viscoelastic material in the lower crust. Since a single relaxation time is not sufficient to model the observed deformation, viscous flow is modelled by a lower crustal Burgers rheology, which has two material relaxation times. The optimum model has a transient viscosity 9 ?? 1017 Pa s, steady-state viscosity 1 ?? 1019 Pa s and a ratio of long term to Maxwell shear modulus of 2:3. This model gives a good fit to GPS stations south of the Kunlun Fault, while displacements at stations north of the fault are over-predicted. We attribute this asymmetry in the GPS residual to lateral heterogeneity in rheological structure across the southern margin of the Qaidam Basin, with thinner crust/higher viscosities beneath the basin than beneath the Tibetan Plateau. Deep afterslip localized in a shear zone beneath the fault rupture gives a reasonable match to the observed InSAR data, but the slip model does not fit the earlier GPS data well. We conclude that while some localized afterslip likely occurred during the early post-seismic phase, the bulk of the observed deformation signal is due to viscous flow in the lower crust. To investigate regional variability in rheological structure, we also analyse post-seismic displacements following the 1997 Manyi earthquake that occurred 250 km west of the Kokoxili rupture. We find that viscoelastic properties are the same as for the Kokoxili area except for the transient viscosity, which is 5 ?? 1017 Pa s. The viscosities estimated for the Manyi and Kokoxili areas are consistent with constraints obtained from other earthquakes in the northwest and south central parts of the Tibetan Plateau. ?? 2011 The Authors Geophysical Journal International ?? 2011 RAS.

Coseismic and Afterslip Model Related to 25 April 2015, Mw7.8 Gorkha, Nepal Earthquake and its Potential Future Risk Regions

NASA Astrophysics Data System (ADS)

Wang, S.; Xu, C.; Jiang, G.

2016-12-01

Evidences from geologic, geophysical and geomorphic prove that 2015 Mw 7.8 Gorkha(Nepal) earthquake happened on the two ramp-flats fault structure of Main Himalayan Thrust(MHT). We approximated this more realistic fault model by a smooth curved fault surface, which was derived by the method of hybrid iterative inversion algorithm(HIIA) with additional constraints from coseismic geodetic data. Then the coseismic slip distribution of 2015 Gorkha earthquake was imaged based on this curved variably triangular sized fault model. The inverted maximum thrust and right-lateral slip components are 6 and 1.5 m, respectively, with the maximum slip magnitude 6.2 m located at a depth of 15 km. The released seismic moment derived from our best slip model is 8.58×1020 Nm, equivalent to a moment magnitude of Mw 7.89. We find two interesting tongue-shape slip areas, the maximum slip is about 1.5 m, along the up-dip of fault plane, which tappers off at the depth of 7 km, the up-dip propagation of ruptures may be impeded by the complicated geometry structures on the MHT interface. Coulomb Failure Stress(CFS), triggered by our optimal slip model, indicating a potential shallower rupture in the future. Considering historical earthquakes distribution and the calculated strain and strain gradient before this earthquake, earthquakes are expected to occur in the northwest areas of the epicenter. The spatio-temporal afterslip model over the first 180 days following the Mw 7.8 main shock was infered from the post-seismic GPS time series. One significant afterslip region can be observed in the downdip of the regions that ruptured by coseismic slip. Another afterslip region arresting our attention, is located around 40 km depth, with about 180 mm slip amplitude, but tappers off at the depth of 50 km. What's more, afterslip mainly occurs within 100 days after the 2015 Gorkha earthquake. Under the assumption of rigidity modulus u = 30 GPa, the released seismic moment by afterslip corresponding to 8.0×1019 Nm, equivalent moment magnitude is Mw 7.23. Our coseismic and afterslip models are in line with previous studies, but with a more accurate geometric fault model.

The Computational Fluid Dynamics Rupture Challenge 2013—Phase I: prediction of rupture status in intracranial aneurysms.

PubMed

Janiga, G; Berg, P; Sugiyama, S; Kono, K; Steinman, D A

2015-03-01

Rupture risk assessment for intracranial aneurysms remains challenging, and risk factors, including wall shear stress, are discussed controversially. The primary purpose of the presented challenge was to determine how consistently aneurysm rupture status and rupture site could be identified on the basis of computational fluid dynamics. Two geometrically similar MCA aneurysms were selected, 1 ruptured, 1 unruptured. Participating computational fluid dynamics groups were blinded as to which case was ruptured. Participants were provided with digitally segmented lumen geometries and, for this phase of the challenge, were free to choose their own flow rates, blood rheologies, and so forth. Participants were asked to report which case had ruptured and the likely site of rupture. In parallel, lumen geometries were provided to a group of neurosurgeons for their predictions of rupture status and site. Of 26 participating computational fluid dynamics groups, 21 (81%) correctly identified the ruptured case. Although the known rupture site was associated with low and oscillatory wall shear stress, most groups identified other sites, some of which also experienced low and oscillatory shear. Of the 43 participating neurosurgeons, 39 (91%) identified the ruptured case. None correctly identified the rupture site. Geometric or hemodynamic considerations favor identification of rupture status; however, retrospective identification of the rupture site remains a challenge for both engineers and clinicians. A more precise understanding of the hemodynamic factors involved in aneurysm wall pathology is likely required for computational fluid dynamics to add value to current clinical decision-making regarding rupture risk. © 2015 by American Journal of Neuroradiology.

The Impact of Interpersonal Style on Ruptures and Repairs in the Therapeutic Alliance Between Offenders and Therapists in Sex Offender Treatment.

PubMed

Watson, Rachael; Thomas, Stuart; Daffern, Michael

2017-10-01

The therapeutic relationship is a critical component of psychological treatment. Strain can occur in the relationship, particularly when working with offenders, and more specifically, those offenders with interpersonal difficulties; strain can lead to a rupture, which may affect treatment participation and performance. This study examined ruptures in the therapeutic relationship in sexual offenders participating in offense-focused group treatment. Fifty-four sex offenders rated the therapeutic alliance at the commencement and completion of treatment; at the completion of treatment, they also reported on the occurrence of ruptures and whether they believed these ruptures were repaired. Ruptures were separated by type, according to severity-Each relationship was therefore characterized as experiencing no rupture, a minor rupture, or a major rupture. Offender characteristics including interpersonal style (IPS) and psychopathy were assessed at the commencement of treatment; their relationship with ruptures was examined. Results revealed that more than half of the offenders (approximately 55%) experienced a rupture in the therapeutic alliance, with one in four of these ruptures remaining unresolved. Offenders who did not report a rupture rated the therapeutic alliance significantly higher at the end of treatment compared with those offenders who reported a rupture that was not repaired. Offenders who reported a major rupture in the therapeutic relationship were higher in interpersonal hostility and hostile-dominance. No interpersonal or offense-specific factors affected the likelihood of a rupture repair.

Estimating rupture distances without a rupture

USGS Publications Warehouse

Thompson, Eric M.; Worden, Charles

2017-01-01

Most ground motion prediction equations (GMPEs) require distances that are defined relative to a rupture model, such as the distance to the surface projection of the rupture (RJB) or the closest distance to the rupture plane (RRUP). There are a number of situations in which GMPEs are used where it is either necessary or advantageous to derive rupture distances from point-source distance metrics, such as hypocentral (RHYP) or epicentral (REPI) distance. For ShakeMap, it is necessary to provide an estimate of the shaking levels for events without rupture models, and before rupture models are available for events that eventually do have rupture models. In probabilistic seismic hazard analysis, it is often convenient to use point-source distances for gridded seismicity sources, particularly if a preferred orientation is unknown. This avoids the computationally cumbersome task of computing rupture-based distances for virtual rupture planes across all strikes and dips for each source. We derive average rupture distances conditioned on REPI, magnitude, and (optionally) back azimuth, for a variety of assumed seismological constraints. Additionally, we derive adjustment factors for GMPE standard deviations that reflect the added uncertainty in the ground motion estimation when point-source distances are used to estimate rupture distances.

Analysis of 30 breast implant rupture cases.

PubMed

Tark, Kwan Chul; Jeong, Hii Sun; Roh, Tae Suk; Choi, Jong Woo

2005-01-01

Breast implants used for augmentation mammoplasty or breast reconstruction could rupture from various causes such as trauma or spontaneous failure. The objectives of this study were to investigate the relationships between the causes of implant rupture and the degree of capsular contracture, and then to evaluate the relative efficacies of specific signs on magnetic resonance imaging (MRI) known to be beneficial for diagnosing the rupture. A retrospective review identified patients with prosthetic implant rupture or impending rupture treated by the senior author. The 30 cases of implant rupture available for review were classified into two groups: intracapsular and extracapsular ruptures. The 30 cases of breast implant ruptures were analyzed with respect to the clinical symptoms and signs, the causes of rupture, the degree of capsular contracture, and therapeutic plans. Among the 30 cases, 14 patients who had undergone MRI during the diagnostic period were analyzed with respect to the relationships between MRI readings and operative findings. Spontaneous rupture of membranes was most common (80%), followed by failure because of trauma (7%) and valve or implant base (4%). The symptoms during implant rupture were contour deformity, palpated mass-like lesions, pain, and focal inflammation. According to the analysis of specific MRI signs, the sensitivity and specificity of the linguine sign were 87% and 100%, respectively, for intracapsular rupture. For extracapsular rupture, the sensitivity and specificity of the linguine sign were, respectively, 67% and 75%. The sensitivity and specificity of the rat-tail sign and tear drop sign were 14% and 50%, respectively. Breast implant rupture was correlated with the degree of capsular contracture in our study. Among the various specific MRI signs used in diagnosing the rupture, the linguine sign was reliable and had a high sensitivity and specificity, especially in cases of intracapsular rupture. On the other hand, the rat-tail and tear drop signs were nonspecific signs for diagnosing the rupture of breast implant.

A simple model for constant storage modulus of poly (lactic acid)/poly (ethylene oxide)/carbon nanotubes nanocomposites at low frequencies assuming the properties of interphase regions and networks.

PubMed

Zare, Yasser; Rhim, Sungsoo; Garmabi, Hamid; Rhee, Kyong Yop

2018-04-01

The networks of nanoparticles in nanocomposites cause solid-like behavior demonstrating a constant storage modulus at low frequencies. This study examines the storage modulus of poly (lactic acid)/poly (ethylene oxide)/carbon nanotubes (CNT) nanocomposites. The experimental data of the storage modulus in the plateau regions are obtained by a frequency sweep test. In addition, a simple model is developed to predict the constant storage modulus assuming the properties of the interphase regions and the CNT networks. The model calculations are compared with the experimental results, and the parametric analyses are applied to validate the predictability of the developed model. The calculations properly agree with the experimental data at all polymer and CNT concentrations. Moreover, all parameters acceptably modulate the constant storage modulus. The percentage of the networked CNT, the modulus of networks, and the thickness and modulus of the interphase regions directly govern the storage modulus of nanocomposites. The outputs reveal the important roles of the interphase properties in the storage modulus. Copyright © 2018 Elsevier Ltd. All rights reserved.

Alliance ruptures and rupture resolution in cognitive-behavior therapy: a preliminary task analysis.

PubMed

Aspland, Helen; Llewelyn, Susan; Hardy, Gillian E; Barkham, Michael; Stiles, William

2008-11-01

An initial ideal, rational model of alliance rupture and rupture resolution provided by cognitive-behavioral therapy (CBT) experts was assessed and compared with empirical observations of ruptures and their resolution in two cases of successful CBT. The initial rational model emphasized nondefensive acknowledgment and exploration of the rupture. Results indicated differences between what therapists think they should do to resolve ruptures and what they actually do and suggested that the rational model should be expanded to emphasize client validation and empowerment. Therapists' ability to attend to ruptures emerged as an important clinical skill.

A Retrospective Analysis of Ruptured Breast Implants

PubMed Central

Baek, Woo Yeol; Lew, Dae Hyun

2014-01-01

Background Rupture is an important complication of breast implants. Before cohesive gel silicone implants, rupture rates of both saline and silicone breast implants were over 10%. Through an analysis of ruptured implants, we can determine the various factors related to ruptured implants. Methods We performed a retrospective review of 72 implants that were removed for implant rupture between 2005 and 2014 at a single institution. The following data were collected: type of implants (saline or silicone), duration of implantation, type of implant shell, degree of capsular contracture, associated symptoms, cause of rupture, diagnostic tools, and management. Results Forty-five Saline implants and 27 silicone implants were used. Rupture was diagnosed at a mean of 5.6 and 12 years after insertion of saline and silicone implants, respectively. There was no association between shell type and risk of rupture. Spontaneous was the most common reason for the rupture. Rupture management was implant change (39 case), microfat graft (2 case), removal only (14 case), and follow-up loss (17 case). Conclusions Saline implants have a shorter average duration of rupture, but diagnosis is easier and safer, leading to fewer complications. Previous-generation silicone implants required frequent follow-up observation, and it is recommended that they be changed to a cohesive gel implant before hidden rupture occurs. PMID:25396188

Rupture of the Pitáycachi Fault in the 1887 Mw 7.5 Sonora, Mexico earthquake (southern Basin-and-Range Province): Rupture kinematics and epicenter inferred from rupture branching patterns

NASA Astrophysics Data System (ADS)

Suter, Max

2015-01-01

During the 3 May 1887 Mw 7.5 Sonora earthquake (surface rupture end-to-end length: 101.8 km), an array of three north-south striking Basin-and-Range Province faults (from north to south Pitáycachi, Teras, and Otates) slipped sequentially along the western margin of the Sierra Madre Occidental Plateau. This detailed field survey of the 1887 earthquake rupture zone along the Pitáycachi fault includes mapping the rupture scarp and measurements of surface deformation. The surface rupture has an endpoint-to-endpoint length of ≥41.0 km, dips 70°W, and is characterized by normal left-lateral extension. The maximum surface offset is 487 cm and the mean offset 260 cm. The rupture trace shows a complex pattern of second-order segmentation. However, this segmentation is not expressed in the 1887 along-rupture surface offset profile, which indicates that the secondary segments are linked at depth into a single coherent fault surface. The Pitáycachi surface rupture shows a well-developed bipolar branching pattern suggesting that the rupture originated in its central part, where the polarity of the rupture bifurcations changes. Most likely the rupture first propagated bilaterally along the Pitáycachi fault. The southern rupture front likely jumped across a step over to the Teras fault and from there across a major relay zone to the Otates fault. Branching probably resulted from the lateral propagation of the rupture after breaching the seismogenic part of the crust, given that the much shorter ruptures of the Otates and Teras segments did not develop branches.

Rupture directivity of moderate earthquakes in northern California

USGS Publications Warehouse

Seekins, Linda C.; Boatwright, John

2010-01-01

We invert peak ground velocity and acceleration (PGV and PGA) to estimate rupture direction and rupture velocity for 47 moderate earthquakes (3.5≥M≥5.4) in northern California. We correct sets of PGAs and PGVs recorded at stations less than 55–125 km, depending on source depth, for site amplification and source–receiver distance, then fit the residual peak motions to the unilateral directivity function of Ben-Menahem (1961). We independently invert PGA and PGV. The rupture direction can be determined using as few as seven peak motions if the station distribution is sufficient. The rupture velocity is unstable, however, if there are no takeoff angles within 30° of the rupture direction. Rupture velocities are generally subsonic (0.5β–0.9β); for stability, we limit the rupture velocity at v=0.92β, the Rayleigh wave speed. For 73 of 94 inversions, the rupture direction clearly identifies one of the nodal planes as the fault plane. The 35 strike-slip earthquakes have rupture directions that range from nearly horizontal (6 events) to directly updip (5 events); the other 24 rupture partly along strike and partly updip. Two strike-slip earthquakes rupture updip in one inversion and downdip in the other. All but 1 of the 11 thrust earthquakes rupture predominantly updip. We compare the rupture directions for 10 M≥4.0 earthquakes to the relative location of the mainshock and the first two weeks of aftershocks. Spatial distributions of 8 of 10 aftershock sequences agree well with the rupture directivity calculated for the mainshock.

Rupture process of the 2013 Okhotsk deep mega earthquake from iterative backprojection and compress sensing methods

NASA Astrophysics Data System (ADS)

Qin, W.; Yin, J.; Yao, H.

2013-12-01

On May 24th 2013 a Mw 8.3 normal faulting earthquake occurred at a depth of approximately 600 km beneath the sea of Okhotsk, Russia. It is a rare mega earthquake that ever occurred at such a great depth. We use the time-domain iterative backprojection (IBP) method [1] and also the frequency-domain compressive sensing (CS) technique[2] to investigate the rupture process and energy radiation of this mega earthquake. We currently use the teleseismic P-wave data from about 350 stations of USArray. IBP is an improved method of the traditional backprojection method, which more accurately locates subevents (energy burst) during earthquake rupture and determines the rupture speeds. The total rupture duration of this earthquake is about 35 s with a nearly N-S rupture direction. We find that the rupture is bilateral in the beginning 15 seconds with slow rupture speeds: about 2.5km/s for the northward rupture and about 2 km/s for the southward rupture. After that, the northward rupture stopped while the rupture towards south continued. The average southward rupture speed between 20-35 s is approximately 5 km/s, lower than the shear wave speed (about 5.5 km/s) at the hypocenter depth. The total rupture length is about 140km, in a nearly N-S direction, with a southward rupture length about 100 km and a northward rupture length about 40 km. We also use the CS method, a sparse source inversion technique, to study the frequency-dependent seismic radiation of this mega earthquake. We observe clear along-strike frequency dependence of the spatial and temporal distribution of seismic radiation and rupture process. The results from both methods are generally similar. In the next step, we'll use data from dense arrays in southwest China and also global stations for further analysis in order to more comprehensively study the rupture process of this deep mega earthquake. Reference [1] Yao H, Shearer P M, Gerstoft P. Subevent location and rupture imaging using iterative backprojection for the 2011 Tohoku Mw 9.0 earthquake. Geophysical Journal International, 2012, 190(2): 1152-1168. [2]Yao H, Gerstoft P, Shearer P M, et al. Compressive sensing of the Tohoku-Oki Mw 9.0 earthquake: Frequency-dependent rupture modes. Geophysical Research Letters, 2011, 38(20).

Persistent rupture terminations at a restraining bend from slip rates on the eastern Altyn Tagh fault

NASA Astrophysics Data System (ADS)

Elliott, A. J.; Oskin, M. E.; Liu-zeng, J.; Shao, Y.-X.

2018-05-01

Restraining double-bends along strike-slip faults inhibit or permit throughgoing ruptures depending on bend angle, length, and prior rupture history. Modeling predicts that for mature strike-slip faults in a regional stress regime characterized by simple shear, a restraining bend of >18° and >4 km length impedes propagating rupture. Indeed, natural evidence shows that the most recent rupture(s) of the Xorkoli section (90°-93°E) of the eastern Altyn Tagh fault (ATF) ended at large restraining bends. However, when multiple seismic cycles are considered in numerical dynamic rupture modeling, heterogeneous residual stresses enable some ruptures to propagate further, modulating whether the bends persistently serve as barriers. These models remain to be tested using observations of the cumulative effects of multiple earthquake ruptures. Here we investigate whether a large restraining double-bend on the ATF serves consistently as a barrier to rupture by measuring long-term slip rates around the terminus of its most recent surface rupture at the Aksay bend. Our results show a W-E decline in slip as the SATF enters the bend, as would be predicted from repeated rupture terminations there. Prior work demonstrated no Holocene slip on the central, most misoriented portion of the bend, while 19-79 m offsets suggest that multiple ruptures have occurred on the west side of the bend during the Holocene. Thus we conclude the gradient in the SATF's slip rate results from the repeated termination of earthquake ruptures there. However, a finite slip rate east of the bend represents the transmission of some slip, suggesting that a small fraction of ruptures may fully traverse or jump the double-bend. This agreement between natural observations of slip accumulation and multi-cycle models of fault rupture enables us to translate observed slip rates into insight about the dynamic rupture process of individual earthquakes as they encounter geometric complexities along faults.

An insight on correlations between kinematic rupture parameters from dynamic ruptures on rough faults

NASA Astrophysics Data System (ADS)

Thingbijam, Kiran Kumar; Galis, Martin; Vyas, Jagdish; Mai, P. Martin

2017-04-01

We examine the spatial interdependence between kinematic parameters of earthquake rupture, which include slip, rise-time (total duration of slip), acceleration time (time-to-peak slip velocity), peak slip velocity, and rupture velocity. These parameters were inferred from dynamic rupture models obtained by simulating spontaneous rupture on faults with varying degree of surface-roughness. We observe that the correlations between these parameters are better described by non-linear correlations (that is, on logarithm-logarithm scale) than by linear correlations. Slip and rise-time are positively correlated while these two parameters do not correlate with acceleration time, peak slip velocity, and rupture velocity. On the other hand, peak slip velocity correlates positively with rupture velocity but negatively with acceleration time. Acceleration time correlates negatively with rupture velocity. However, the observed correlations could be due to weak heterogeneity of the slip distributions given by the dynamic models. Therefore, the observed correlations may apply only to those parts of rupture plane with weak slip heterogeneity if earthquake-rupture associate highly heterogeneous slip distributions. Our findings will help to improve pseudo-dynamic rupture generators for efficient broadband ground-motion simulations for seismic hazard studies.

Fault Branching and Long-Term Earthquake Rupture Scenario for Strike-Slip Earthquake

NASA Astrophysics Data System (ADS)

Klinger, Y.; CHOI, J. H.; Vallage, A.

2017-12-01

Careful examination of surface rupture for large continental strike-slip earthquakes reveals that for the majority of earthquakes, at least one major branch is involved in the rupture pattern. Often, branching might be either related to the location of the epicenter or located toward the end of the rupture, and possibly related to the stopping of the rupture. In this work, we examine large continental earthquakes that show significant branches at different scales and for which ground surface rupture has been mapped in great details. In each case, rupture conditions are described, including dynamic parameters, past earthquakes history, and regional stress orientation, to see if the dynamic stress field would a priori favor branching. In one case we show that rupture propagation and branching are directly impacted by preexisting geological structures. These structures serve as pathways for the rupture attempting to propagate out of its shear plane. At larger scale, we show that in some cases, rupturing a branch might be systematic, hampering possibilities for the development of a larger seismic rupture. Long-term geomorphology hints at the existence of a strong asperity in the zone where the rupture branched off the main fault. There, no evidence of throughgoing rupture could be seen along the main fault, while the branch is well connected to the main fault. This set of observations suggests that for specific configurations, some rupture scenarios involving systematic branching are more likely than others.

Ground motion hazard from supershear rupture

USGS Publications Warehouse

Andrews, D.J.

2010-01-01

An idealized rupture, propagating smoothly near a terminal rupture velocity, radiates energy that is focused into a beam. For rupture velocity less than the S-wave speed, radiated energy is concentrated in a beam of intense fault-normal velocity near the projection of the rupture trace. Although confined to a narrow range of azimuths, this beam diverges and attenuates. For rupture velocity greater than the S-wave speed, radiated energy is concentrated in Mach waves forming a pair of beams propagating obliquely away from the fault. These beams do not attenuate until diffraction becomes effective at large distance. Events with supershear and sub-Rayleigh rupture velocity are compared in 2D plane-strain calculations with equal stress drop, fracture energy, and rupture length; only static friction is changed to determine the rupture velocity. Peak velocity in the sub-Rayleigh case near the termination of rupture is larger than peak velocity in the Mach wave in the supershear case. The occurrence of supershear rupture propagation reduces the most intense peak ground velocity near the fault, but it increases peak velocity within a beam at greater distances.

Slow rupture of frictional interfaces

NASA Astrophysics Data System (ADS)

Bar Sinai, Yohai; Brener, Efim A.; Bouchbinder, Eran

2012-02-01

The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not completely understood. We show that slow rupture is an intrinsic and robust property of simple non-monotonic rate-and-state friction laws. It is associated with a new velocity scale cmin, determined by the friction law, below which steady state rupture cannot propagate. We further show that rupture can occur in a continuum of states, spanning a wide range of velocities from cmin to elastic wave-speeds, and predict different properties for slow rupture and ordinary fast rupture. Our results are qualitatively consistent with recent high-resolution laboratory experiments and may provide a theoretical framework for understanding slow rupture phenomena along frictional interfaces.

The influence of atmospheric pressure on aortic aneurysm rupture--is the diameter of the aneurysm important?

PubMed

Urbanek, Tomasz; Juśko, Maciej; Niewiem, Alfred; Kuczmik, Wacław; Ziaja, Damian; Ziaja, Krzysztof

2015-01-01

The rate of aortic aneurysm rupture correlates with the aneurysm's diameter, and a higher rate of rupture is observed in patients with larger aneurysms. According to the literature, contradictory results concerning the relationship between atmospheric pressure and aneurysm size have been reported. In this paper, we assessed the influence of changes in atmospheric pressure on abdominal aneurysm ruptures in relationship to the aneurysm's size. The records of 223 patients with ruptured abdominal aneurysms were evaluated. All of the patients had been admitted to the department in the period 1997-2007 from the Silesia region. The atmospheric pressures on the day of the rupture and on the days both before the rupture and between the rupture events were compared. The size of the aneurysm was also considered in the analysis. There were no statistically significant differences in pressure between the days of rupture and the remainder of the days within an analysed period. The highest frequency of the admission of patients with a ruptured aortic aneurysm was observed during periods of winter and spring, when the highest mean values of atmospheric pressure were observed; however, this observation was not statistically confirmed. A statistically non-significant trend towards the higher rupture of large aneurysms (> 7 cm) was observed in the cases where the pressure increased between the day before the rupture and the day of the rupture. This trend was particularly pronounced in patients suffering from hypertension (p = 0.1). The results of this study do not support the hypothesis that there is a direct link between atmospheric pressure values and abdominal aortic aneurysm ruptures.

Insights gained from relating cumulative seismic moments to fluid injection activities

NASA Astrophysics Data System (ADS)

McGarr, A.; Barbour, A. J.

2017-12-01

The three earthquakes with magnitudes of 5 or greater that were induced in Oklahoma during 2016 motivated efforts to improve our understanding of how fluid injection operations are related to earthquake activity. In this study, we have addressed the question of whether the volume of fluid injected down wells within 10 km of the mainshock of an induced earthquake sequence can account for its total moment release. Specifically, is the total moment release equal to, or less than, twice the product of the shear modulus and the total volume injected (McGarr, JGR, 2014, equation 7)? In contrast to McGarr's (2014, equation 13) relationship for the maximum moment, M0(max), the relationship for the total moment release has the advantage of being independent of the magnitude distribution. We find that the three sequences in Oklahoma in 2016, M5.1 Fairview, M5.8 Pawnee, M5.0 Cushing, and the 2011 M5.7 Prague sequence all adhere to this relationship. We also found that eight additional sequences of earthquakes induced by various fluid injection activities, widely distributed worldwide, show the same relationship between total moment-release and injected volume. Thus, for injected volumes ranging from 103 up to 107 cubic m, the moment release of an induced earthquake sequence appears to be similarly limited. These results imply that M0(max) for a sequence induced by fluid injection could be as high as twice the product of the shear modulus and the injected volume if the mainshock in the sequence accounts for nearly all of the total moment, as was the case for the 2016 Pawnee M5.8 mainshock. This new upper bound for maximum moment is twice what was proposed by McGarr (2014, equation 13). Our new results also support the assumption in our analysis that the induced earthquake rupture is localized to the seismogenic region that is weakened owing to a pore pressure increase of the order of a seismic stress drop.

Relaxation of the bulk modulus in partially molten dunite?

NASA Astrophysics Data System (ADS)

Cline, C. J.; Jackson, I.

2016-11-01

To address the possibility of melt-related bulk modulus relaxation, a forced oscillation experiment was conducted at seismic frequencies on a partially molten synthetic dunite specimen (melt fraction = 0.026) utilizing the enhanced capacity of the Australian National University attenuation apparatus to operate in both torsional and flexural oscillation modes. Shear modulus and dissipation data are consistent with those for melt-bearing olivine specimens previously tested in torsion, with a pronounced dissipation peak superimposed on high-temperature background. Flexural data exhibit a monotonic decrease in complex Young's modulus with increasing temperature under transsolidus temperatures. The observed variation of Young's modulus is well described by the relationship 1/E 1/3G, without requiring relaxation of the bulk modulus. At high homologous temperatures, when shear modulus is low, extensional and flexural oscillation measurements have little resolution of bulk modulus, and thus, only pressure oscillation measurements can definitively constrain bulk properties at these conditions.

Module isolation devices

DOEpatents

Carolan, Michael Francis; Cooke, John Albert; Buzinski, Michael David

2010-04-27

A gas flow isolation device includes a gas flow isolation valve movable from an opened condition to a closed condition. The module isolation valve in one embodiment includes a rupture disk in flow communication with a flow of gas when the module isolation valve is in an opened condition. The rupture disk ruptures when a predetermined pressure differential occurs across it causing the isolation valve to close. In one embodiment the valve is mechanically linked to the rupture disk to maintain the valve in an opened condition when the rupture disk is intact, and which permits the valve to move into a closed condition when the rupture disk ruptures. In another embodiment a crushable member maintains the valve in an open condition, and the flow of gas passed the valve upon rupturing of the rupture disk compresses the crushable member to close the isolation valve.

The transition of dynamic rupture styles in elastic media under velocity-weakening friction

NASA Astrophysics Data System (ADS)

Gabriel, A.-A.; Ampuero, J.-P.; Dalguer, L. A.; Mai, P. M.

2012-09-01

Although kinematic earthquake source inversions show dominantly pulse-like subshear rupture behavior, seismological observations, laboratory experiments and theoretical models indicate that earthquakes can operate with different rupture styles: either as pulses or cracks, that propagate at subshear or supershear speeds. The determination of rupture style and speed has important implications for ground motions and may inform about the state of stress and strength of active fault zones. We conduct 2D in-plane dynamic rupture simulations with a spectral element method to investigate the diversity of rupture styles on faults governed by velocity-and-state-dependent friction with dramatic velocity-weakening at high slip rate. Our rupture models are governed by uniform initial stresses, and are artificially initiated. We identify the conditions that lead to different rupture styles by investigating the transitions between decaying, steady state and growing pulses, cracks, sub-shear and super-shear ruptures as a function of background stress, nucleation size and characteristic velocity at the onset of severe weakening. Our models show that small changes of background stress or nucleation size may lead to dramatic changes of rupture style. We characterize the asymptotic properties of steady state and self-similar pulses as a function of background stress. We show that an earthquake may not be restricted to a single rupture style, but that complex rupture patterns may emerge that consist of multiple rupture fronts, possibly involving different styles and back-propagating fronts. We also demonstrate the possibility of a super-shear transition for pulse-like ruptures. Finally, we draw connections between our findings and recent seismological observations.

The effect of segmented fault zones on earthquake rupture propagation and termination

NASA Astrophysics Data System (ADS)

Huang, Y.

2017-12-01

A fundamental question in earthquake source physics is what can control the nucleation and termination of an earthquake rupture. Besides stress heterogeneities and variations in frictional properties, damaged fault zones (DFZs) that surround major strike-slip faults can contribute significantly to earthquake rupture propagation. Previous earthquake rupture simulations usually characterize DFZs as several-hundred-meter-wide layers with lower seismic velocities than host rocks, and find earthquake ruptures in DFZs can exhibit slip pulses and oscillating rupture speeds that ultimately enhance high-frequency ground motions. However, real DFZs are more complex than the uniform low-velocity structures, and show along-strike variations of damages that may be correlated with historical earthquake ruptures. These segmented structures can either prohibit or assist rupture propagation and significantly affect the final sizes of earthquakes. For example, recent dense array data recorded at the San Jacinto fault zone suggests the existence of three prominent DFZs across the Anza seismic gap and the south section of the Clark branch, while no prominent DFZs were identified near the ends of the Anza seismic gap. To better understand earthquake rupture in segmented fault zones, we will present dynamic rupture simulations that calculate the time-varying rupture process physically by considering the interactions between fault stresses, fault frictional properties, and material heterogeneities. We will show that whether an earthquake rupture can break through the intact rock outside the DFZ depend on the nucleation size of the earthquake and the rupture propagation distance in the DFZ. Moreover, material properties of the DFZ, stress conditions along the fault, and friction properties of the fault also have a critical impact on rupture propagation and termination. We will also present scenarios of San Jacinto earthquake ruptures and show the parameter space that is favorable for rupture propagation through the Anza seismic gap. Our results suggest that a priori knowledge of properties of segmented fault zones is of great importance for predicting sizes of future large earthquakes on major faults.

Spatiotemporal complexity of 2-D rupture nucleation process observed by direct monitoring during large-scale biaxial rock friction experiments

NASA Astrophysics Data System (ADS)

Fukuyama, Eiichi; Tsuchida, Kotoyo; Kawakata, Hironori; Yamashita, Futoshi; Mizoguchi, Kazuo; Xu, Shiqing

2018-05-01

We were able to successfully capture rupture nucleation processes on a 2-D fault surface during large-scale biaxial friction experiments using metagabbro rock specimens. Several rupture nucleation patterns have been detected by a strain gauge array embedded inside the rock specimens as well as by that installed along the edge walls of the fault. In most cases, the unstable rupture started just after the rupture front touched both ends of the rock specimen (i.e., when rupture front extended to the entire width of the fault). In some cases, rupture initiated at multiple locations and the rupture fronts coalesced to generate unstable ruptures, which could only be detected from the observation inside the rock specimen. Therefore, we need to carefully examine the 2-D nucleation process of the rupture especially when analyzing the data measured only outside the rock specimen. At least the measurements should be done at both sides of the fault to identify the asymmetric rupture propagation on the fault surface, although this is not perfect yet. In the present experiment, we observed three typical types of the 2-D rupture propagation patterns, two of which were initiated at a single location either close to the fault edge or inside the fault. This initiation could be accelerated by the free surface effect at the fault edge. The third one was initiated at multiple locations and had a rupture coalescence at the middle of the fault. These geometrically complicated rupture initiation patterns are important for understanding the earthquake nucleation process in nature.

Compressive and Flexural Tests on Adobe Samples Reinforced with Wire Mesh

NASA Astrophysics Data System (ADS)

Jokhio, G. A.; Al-Tawil, Y. M. Y.; Syed Mohsin, S. M.; Gul, Y.; Ramli, N. I.

2018-03-01

Adobe is an economical, naturally available, and environment friendly construction material that offers excellent thermal and sound insulations as well as indoor air quality. It is important to understand and enhance the mechanical properties of this material, where a high degree of variation is reported in the literature owing to lack of research and standardization in this field. The present paper focuses first on the understanding of mechanical behaviour of adobe subjected to compressive stresses as well as flexure and then on enhancing the same with the help of steel wire mesh as reinforcement. A total of 22 samples were tested out of which, 12 cube samples were tested for compressive strength, whereas 10 beams samples were tested for modulus of rupture. Half of the samples in each category were control samples i.e. without wire mesh reinforcement, whereas the remaining half were reinforced with a single layer of wire mesh per sample. It has been found that the compressive strength of adobe increases by about 43% after adding a single layer of wire mesh reinforcement. The flexural response of adobe has also shown improvement with the addition of wire mesh reinforcement.

Mechanical optimization of the composite biomaterial based on the tricalcium phosphate, titania and magnesium fluoride.

PubMed

Ayadi, Ibticem; Ayed, Foued Ben

2016-07-01

The microstructure, the densification and the mechanical properties of the tricalcium phosphate - titania - MgF2 composites were investigated. The effect of MgF2 addition on the performances of the tricalcium phosphate - 40wt% titania composites is discussed. The mechanical properties were investigated by Brazilian test, Vickers indentation and the ultrasound techniques. The mechanical properties of the tricalcium phosphate - 40wt% titania composites reached optimum performances after the sintering process at 1200°C for one hour with 4wt% MgF2. Thus, the highest values of the rupture strength, Vickers hardness, Young׳s and the shear modulus reached 27MPa, 360Hv, 51GPa and 20GPa, respectively. The increase of the mechanical properties of the composites is due to the presence of the liquid phase and the formation of a new compound. Thus, the microstructure of the composites reveals the presence of a new lamella form relative to the Mg2(PO4)F. Beyond 4wt% MgF2, the performances of the composites are hindered by the exaggerated grain growth and the formation of the bubbles. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development of Tissue-Engineered Ligaments: Elastin Promotes Regeneration of the Rabbit Medial Collateral Ligament.

PubMed

Hirukawa, Masaki; Katayama, Shingo; Sato, Tatsuya; Yamada, Masayoshi; Kageyama, Satoshi; Unno, Hironori; Suzuki, Yoshiaki; Miura, Yoshihiro; Shiratsuchi, Eri; Hasegawa, Masahiro; Miyamoto, Keiichi; Horiuchi, Takashi

2017-12-21

When ligaments are injured, reconstructive surgery is sometimes required to restore function. Methods of reconstructive surgery include transplantation of an artificial ligament and autotransplantation of a tendon. However, these methods have limitations related to the strength of the bone-ligament insertion and biocompatibility of the transplanted tissue after surgery. Therefore, it is necessary to develop new reconstruction methods and pursue the development of artificial ligaments. Elastin is a major component of elastic fibers and ligaments. However, the role of elastin in ligament regeneration has not been described. Here, we developed a rabbit model of a medial collateral ligament (MCL) rupture and treated animal knees with exogenous elastin [100 µg/(0.5 mL·week)] for 6 or 12 weeks. Elastin treatment increased gene expression and protein content of collagen and elastin (gene expression, 6-fold and 42-fold, respectively; protein content, 1.6-fold and 1.9-fold, respectively), and also increased the elastic modulus of MCL increased with elastin treatment (2-fold) compared with the controls. Our data suggest that elastin is involved in the regeneration of damaged ligaments. © 2017 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Comportement en fatigue et influence de la temperature sur les proprietes en traction du PLA

NASA Astrophysics Data System (ADS)

Menard, Claire

Current environmental issues reduce the use of materials obtained from fossil resources. The usual plastics therefore tend to be replaced by more green polymers such as polylactic acid (PLA), a bio-based and biodegradable polymer. Knowledge on the properties of this material is essential, especially in terms of fatigue strength and influence of temperature on tensile stiffness and strength. In this study, the PLA samples are submitted to monotonic tensile tests, according to ASTM D638-10, at various temperatures between room temperature (23°C) and the glass transition temperature of the material (55-60°C). The results show a decrease of 30% of the modulus of elasticity and 60% of the tensile strength between these two temperatures. This decrease is mainly due to a significant drop in the mechanical properties beyond 50°C. In addition, tensile fatigue tests were conducted at loads rate between 40 and 80% of tensile strength, at room temperature in order to plot the Wohler curve of PLA. The ruptured specimens were finally observed with a scanning electron microscope (SEM) to analyze the failure mechanisms in fatigue of PLA.

High Temperature Mechanical Behavior of UHTC Coatings for Thermal Protection of Re-Entry Vehicles

NASA Astrophysics Data System (ADS)

Pulci, G.; Tului, M.; Tirillò, J.; Marra, F.; Lionetti, S.; Valente, T.

2011-01-01

In this work, the high temperature mechanical properties of ultra high temperature ceramics (UHTC) coatings deposited by plasma spraying have been investigated; particularly the stress-strain relationship of ZrB2-based thick films has been evaluated by means of 4-point bending tests up to 1500 °C in air. Results show that at each investigated temperature (500, 1000, and 1500 °C) modulus of rupture (MOR) values are higher than the ones obtained at room temperature (RT); moreover at 1500 °C the UHTC coatings exhibit a marked plastic behavior, maintaining a flexural strength 25% higher compared to RT tested samples. The coefficient of linear thermal expansion (CTE) has been evaluated up to 1500 °C: obtained data are of primary importance for substrate selection, interface design and to analyze the thermo-mechanical behavior of coating-substrate coupled system. Finally, SEM-EDS analyses have been carried out on as-sprayed and tested materials in order to understand the mechanisms of reinforcement activated by high temperature exposure and to identify the microstructural modifications induced by the combination of mechanical loads and temperature in an oxidizing environment.

Effect of Be Modification on the Oxide Bifilms and Tensile Strength Reliability of Al-Si-Mg Alloys Containing Excess Fe

NASA Astrophysics Data System (ADS)

Asadian Nozari, M.; Taghiabadi, R.; Karimzadeh, M.; Ghoncheh, M. H.

2018-03-01

The effect of oxide bifilms and Be modification (0.2 wt pct) on the tensile strength reliability of the as-cast and T6 heat-treated Al-9Si-0.35Mg-1.5Fe alloy was investigated using Weibull analysis. For this purpose, the density of oxide bifilms in the molten alloy was intentionally increased by surface agitation. According to the results, Be modifies the β-Al5FeSi particles to the less harmful α-Fe compounds and substantially decreases the bifilm density in the castings leading to improved tensile properties and higher reliability. Moreover, the beneficial effect of Be was found to be more in the samples containing higher amounts of bifilms. For instance, in the heat-treated condition, Be increased the Weibull modulus of the non-agitated and surface-agitated samples by 4 and 94 pct, respectively. This improvement can be attributed to the strengthening effect of Be on the young surface oxides so that they resist more against rupture when melt is subjected to the surface turbulence. The reduced pressure test and fractography investigations also confirmed the reduction of bifilm density and bifilm-related defects in Be-modified samples.

Effect of Be Modification on the Oxide Bifilms and Tensile Strength Reliability of Al-Si-Mg Alloys Containing Excess Fe

NASA Astrophysics Data System (ADS)

Asadian Nozari, M.; Taghiabadi, R.; Karimzadeh, M.; Ghoncheh, M. H.

2018-06-01

The effect of oxide bifilms and Be modification (0.2 wt pct) on the tensile strength reliability of the as-cast and T6 heat-treated Al-9Si-0.35Mg-1.5Fe alloy was investigated using Weibull analysis. For this purpose, the density of oxide bifilms in the molten alloy was intentionally increased by surface agitation. According to the results, Be modifies the β-Al5FeSi particles to the less harmful α-Fe compounds and substantially decreases the bifilm density in the castings leading to improved tensile properties and higher reliability. Moreover, the beneficial effect of Be was found to be more in the samples containing higher amounts of bifilms. For instance, in the heat-treated condition, Be increased the Weibull modulus of the non-agitated and surface-agitated samples by 4 and 94 pct, respectively. This improvement can be attributed to the strengthening effect of Be on the young surface oxides so that they resist more against rupture when melt is subjected to the surface turbulence. The reduced pressure test and fractography investigations also confirmed the reduction of bifilm density and bifilm-related defects in Be-modified samples.

Fracture of Polymers and Interfaces: A Universal Molecular Approach

NASA Astrophysics Data System (ADS)

Wool, Richard

2003-03-01

Fracture of polymers, linear or crosslinked, can be viewed as a breaking of molecular connectivity via disentanglement or bond rupture. When treated as a vector percolation phenomenon, we find that it captures the essential physics of fracture and makes broad accurate predictions for strength S, and fracture energy G, of polymers and their interfaces. In the bulk, we find that G ˜ [p-pc], and S ˜ [p-pc]^1/2, where p is the local normalized entanglement density and pc is the percolation threshold. For interfaces, p = nL/w, where n is the areal density of chains of length L ˜M (mol wt) in an interface of width w. For incompatible interfaces of width w, G ˜ [w-wc]; when reinforced with n compatibilizers, G ˜ (n - nc]. For welding, p ˜ L, the welding time tw ˜ L. For adhesion with sticker group X on the polymer and receptor groups Y on the solid, the strength first increases with X, Y and X-Y strength and then decreases after a predictable maximum. For thermosets, the modulus E ˜ [p-pc]^3 and the strength S ˜ [p-pc]^2. Numerous experimental examples are given to support the above universal relations for fracture.

Recycling of waste tire rubber: Microwave devulcanization and incorporation in a thermoset resin.

PubMed

Aoudia, Karima; Azem, Saïd; Aït Hocine, Nourredine; Gratton, Michel; Pettarin, Valeria; Seghar, Saïd

2017-02-01

This study focused on the possibility of recycling Waste Tire Rubber (WTR) to be used as polymer modifier. Thus, WTR was grinded into powder, at ambient temperature, with a disc mill PQ500 and microwave electromagnetic energy was used to devulcanize this powder with the final aim of producing a new composite by its incorporation in a thermoset resin. The influence of the treatment microwave energy on the devulcanization ratio was investigated. FTIR analysis revealed that rupture of Sulfur-Sulfur (SS) and Carbon-Sulfur (CS) bonds have occurred during the treatment. Swelling analysis showed that the microwave treatment can lead to a very significant degree of devulcanization. The Ground Tire Rubber (GTR) and the Devulcanized Ground Tire Rubber (DGTR) were then separately used to prepare epoxy based composites. It appeared that epoxy composites filled with DGTR have better mechanical properties than those filled with untreated GTR. This result agrees with scanning electron microscopy observations which highlighted a better interface coherence between DGTR and epoxy. A complementary analysis pointed out a linear relationship between the rubber modulus and the number of crosslink per chain. Copyright © 2016 Elsevier Ltd. All rights reserved.

Constraints on moduli cosmology from the production of dark matter and baryon isocurvature fluctuations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lemoine, Martin; Martin, Jerome; Yokoyama, Jun'ichi

2009-12-15

We set constraints on moduli cosmology from the production of dark matter - radiation and baryon -radiation isocurvature fluctuations through modulus decay, assuming the modulus remains light during inflation. We find that the moduli problem becomes worse at the perturbative level as a significant part of the parameter space m{sub {sigma}} (modulus mass) - {sigma}{sub inf} (modulus vacuum expectation value at the end of inflation) is constrained by the nonobservation of significant isocurvature fluctuations. We discuss in detail the evolution of the modulus vacuum expectation value and perturbations, in particular, the consequences of Hubble scale corrections to the modulus potential,more » and the stochastic motion of the modulus during inflation. We show, in particular, that a high modulus mass scale m{sub {sigma}} > or approx. 100 TeV, which allows the modulus to evade big bang nucleosynthesis constraints is strongly constrained at the perturbative level. We find that generically, solving the moduli problem requires the inflationary scale to be much smaller than 10{sup 13} GeV.« less

Control of strong ground motion of mining-induced earthquakes by the strength of the seismogenic rock mass

USGS Publications Warehouse

McGarr, A.

2002-01-01

The shear stress ?? that can be sustained by the rock mass in the environs of a mining-induced earthquake controls the near-fault peak ground velocity v of that event according to v???0.25(??/G) ??, where ?? is the shear wave speed and G is the modulus of rigidity. To estimate ?? at mining depths, I review the results of four studies involving Witwatersrand tremors that relate to the bulk shear strength. The first and most general analysis uses the common assumptions that the seismogenic crust is pervasively faulted, has hydrostatic pore pressure before mining, and an extensional stress state that is close to failure. Mining operations reduce the pore pressure to zero within the mine and redistribute the stresses such that, in localized regions, the state of stress is again at the point of failure. Laboratory friction experiments can be used to estimate ?? in the zero-pore-pressure regime. Second, model calculations of states of stress in the vicinity of milling at about 3 km depth indicated the shear stress available to cause faulting near the centre of a distribution of induced earthquakes. Third, laboratory experiments combined with microscopic analyses of fault gouge from the rupture zone of a mining-induced event provided an estimate of the average shear stress acting on the fault to cause this earthquake at a depth of 2 km. Fourth, moment tensors determined for mining- induced earthquakes usually show substantial implosive components, from which it is straightforward to estimate ??. These four different analyses yield estimates of ?? that fall in the range 30 to 61 MPa which implies that near-fault particle velocities could he as high as about 1.5 m/s. To the extent that the causative fault ruptures previously intact rock, both ?? and v, in localized regions, could be several times higher than 61 MPa and 1.5 m/s.

Interfacial properties, thin film stability and foam stability of casein micelle dispersions.

PubMed

Chen, Min; Sala, Guido; Meinders, Marcel B J; van Valenberg, Hein J F; van der Linden, Erik; Sagis, Leonard M C

2017-01-01

Foam stability of casein micelle dispersions (CMDs) strongly depends on aggregate size. To elucidate the underlying mechanism, the role of interfacial and thin film properties was investigated. CMDs were prepared at 4°C and 20°C, designated as CMD 4°C and CMD 20°C . At equal protein concentrations, foam stability of CMD 4 °C (with casein micelle aggregates) was markedly higher than CMD 20°C (without aggregates). Although the elastic modulus of CMD 4°C was twice as that of CMD 20°C at 0.005Hz, the protein adsorbed amount was slightly higher for CMD 20°C than for CMD 4°C , which indicated a slight difference in interfacial composition of the air/water interface. Non-linear surface dilatational rheology showed minor differences between mechanical properties of air/water interfaces stabilized by two CMDs. These differences in interfacial properties could not explain the large difference in foam stability between two CMDs. Thin film analysis showed that films made with CMD 20°C drained to a more homogeneous film compared to films stabilized by CMD 4°C . Large casein micelle aggregates trapped in the thin film of CMD 4°C made the film more heterogeneous. The rupture time of thin films was significantly longer for CMD 4°C (>1h) than for CMD 20°C (<600s) at equal protein concentration. After homogenization, which broke down the aggregates, the thin films of CMD 4°C became much more homogeneous, and both the rupture time of thin films and foam stability decreased significantly. In conclusion, the increased stability of foam prepared with CMD 4°C appears to be the result of entrapment of casein micelle aggregates in the liquid films of the foam. Copyright © 2016 Elsevier B.V. All rights reserved.

Deformation of conjugate compliant fault zones induced by the 2013 Mw7.7 Baluchistan (Pakistan) earthquake

NASA Astrophysics Data System (ADS)

Dutta, Rishabh; Wang, Teng; Feng, Guangcai; Harrington, Jonathan; Vasyura-Bathke, Hannes; Jónsson, Sigurjón

2017-04-01

Strain localizations in compliant fault zones (with elastic moduli lower than the surrounding rocks) induced by nearby earthquakes have been detected using geodetic observations in a few cases in the past. Here we observe small-scale changes in interferometric Synthetic Aperture Radar (InSAR) measurements along multiple conjugate faults near the rupture of the 2013 Mw7.7 Baluchistan (Pakistan) earthquake. After removing the main coseismic deformation signal in the interferograms and correcting them for topography-related phase, we observe 2-3 cm signal along several conjugate faults that are 15-30 km from the mainshock fault rupture. These conjugate compliant faults have strikes of N30°E and N45°W. The sense of motion indicates left-lateral deformation across the N30°E faults and right-lateral deformation across the N45°W faults, which suggests the conjugate faults were subjected to extensional coseismic stresses along the WSW-ENE direction. The spacing between the different sets of faults is around 5 to 8 km. We explain the observed strain localizations as an elastic response of the compliant conjugate faults induced by the Baluchistan earthquake. Using 3D Finite Element models (FEM), we impose coseismic static displacements due to the earthquake along the boundaries of the FEM domain to reproduce the coseismic stress changes acting across the compliant faults. The InSAR measurements are used to constrain the geometry and rigidity variations of the compliant faults with respect to the surrounding rocks. The best fitting models show the compliant fault zones to have a width of 0.5 km to 2 km and a reduction of the shear modulus by a factor of 3 to 4. Our study yields similar values as were found for compliant fault zones near the 1992 Landers and the 1999 Hector Mine earthquakes in California, although here the strain localization is occurring on more complex conjugate sets of faults.

Rabbit Achilles tendon full transection model – wound healing, adhesion formation and biomechanics at 3, 6 and 12 weeks post-surgery

PubMed Central

Meier Bürgisser, Gabriella; Calcagni, Maurizio; Bachmann, Elias; Fessel, Gion; Snedeker, Jess G.; Giovanoli, Pietro

2016-01-01

ABSTRACT After tendon rupture repair, two main problems may occur: re-rupture and adhesion formation. Suitable non-murine animal models are needed to study the healing tendon in terms of biomechanical properties and extent of adhesion formation. In this study 24 New Zealand White rabbits received a full transection of the Achilles tendon 2 cm above the calcaneus, sutured with a 4-strand Becker suture. Post-surgical analysis was performed at 3, 6 and 12 weeks. In the 6-week group, animals received a cast either in a 180 deg stretched position during 6 weeks (adhesion provoking immobilization), or were re-casted with a 150 deg position after 3 weeks (adhesion inhibiting immobilization), while in the other groups (3 and 12 weeks) a 180 deg position cast was applied for 3 weeks. Adhesion extent was analyzed by histology and ultrasound. Histopathological scoring was performed according to a method by Stoll et al. (2011), and the main biomechanical properties were assessed. Histopathological scores increased as a function of time, but did not reach values of healthy tendons after 12 weeks (only around 15 out of 20 points). Adhesion provoking immobilization led to an adhesion extent of 82.7±9.7%, while adhesion inhibiting immobilization led to 31.9±9.8% after 6 weeks. Biomechanical properties increased over time, however, they did not reach full strength nor elastic modulus at 12 weeks post-operation. Furthermore, the rabbit Achilles tendon model can be modulated in terms of adhesion formation to the surrounding tissue. It clearly shows the different healing stages in terms of histopathology and offers a suitable model regarding biomechanics because it exhibits similar biomechanics as the human flexor tendons of the hand. PMID:27635037

Thermostructural Properties Of Sic/Sic Panels With 2.5d And 3d Fiber Architectures

NASA Technical Reports Server (NTRS)

Yun, H. M.; DeCarlo, J. A.; Bhatt, R. H.; Jaskowiak, M. H.

2005-01-01

CMC hot-section components in advanced engines for power and propulsion will typically require high cracking strength, high ultimate strength and strain, high creep- rupture resistance, and high thermal conductivity in all directions. In the past, NASA has demonstrated fabrication of a variety of SiC/SiC flat panels and round tubes with various 2D fiber architectures using the high-modulus high-performance Sylramic-iBN Sic fiber and Sic-based matrices derived by CVI, MI, and/or PIP processes. The thermo- mechanical properties of these CMC have shown state-of-the-art performance, but primarily in the in-plane directions. Currently NASA is extending the thermostructural capability of these SiC/SiC systems in the thru-thickness direction by using various 2.5D and 3D fiber architectures. NASA is also using specially designed fabrication steps to optimize the properties of the BN-based interphase and Sic-based matrices. In this study, Sylramic-iBN/SiC panels with 2D plain weave, 2.5D satin weave, 2.5D ply-to-ply interlock weave, and 3D angle interlock fiber architectures, all woven at AITI, were fabricated using matrix densification routes previously established between NASA and GEPSC for CVI-MI processes and between NASA and Starfire-Systems for PIP processes. Introduction of the 2.5 D fiber architecture along with an improved matrix process was found to increase inter-laminar tensile strength from 1.5 -2 to 3 - 4 ksi and thru-thickness thermal conductivity from 15-20 to 30-35 BTU/ft.hr.F with minimal reduction in in-plane strength and creep-rupture properties. Such improvements should reduce thermal stresses and increase the thermostructural operating envelope for SiC/SiC engine components. These results are analyzed to offer general guidelines for selecting fiber architectures and constituent processes for high-performance SiC/SiC engine components.

Re-rupture rate of primarily repaired distal biceps tendon injuries.

PubMed

Hinchey, John W; Aronowitz, Jessica G; Sanchez-Sotelo, Joaquin; Morrey, Bernard F

2014-06-01

Distal biceps tendon rupture is a common injury, and primary repair results in excellent return of function and strength. Complications resulting from distal biceps tendon repairs are well reported, but the incidence of re-ruptures has never been investigated. A search of the Mayo Clinic's Medical/Surgical Index was performed, and all distal biceps tendon repairs from January 1981 through May 2009 were identified. All patients who completed 12 months or more of follow-up were included. All charts were reviewed and patients contacted as necessary to identify a re-rupture. We also investigated the situation causing the re-rupture. We identified a total of 190 distal biceps tendon ruptures that underwent repair and met our inclusion and exclusion criteria. Of the 190 repairs, 172 (90.5%) were performed by the Mayo modification of the Boyd-Anderson 2-incision technique. Bilateral ruptures occurred in 13 patients (7.3%). Six primary ruptures (3.2%) occurred in women, 4 of the 6 being partial ruptures. Partial ruptures were found to be statistically more common than complete ruptures in women (P = .05). We identified 3 re-ruptures (1.5%), all occurring within 3 weeks of the index surgery. The re-rupture rate after primary repair of the distal biceps tendon is low at 1.5% and occurs within 3 weeks of index repair. This appears to be due to patient compliance and excessive force placed on repairs. We also found the incidence of women who sustain a distal biceps tendon tear to be 3.2%, with partial tears being statistically more common than complete ruptures. Level IV, case series, treatment study Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

Kinematic Rupture Process of the 2015 Gorkha (Nepal) Earthquake Sequence from Joint Inversion of Teleseismic, hr-GPS, Strong-Ground Motion, InSAR interferograms and pixel offsets

NASA Astrophysics Data System (ADS)

Yue, H.; Simons, M.; Jiang, J.; Fielding, E. J.; Owen, S. E.; Moore, A. W.; Riel, B. V.; Polet, J.; Duputel, Z.; Samsonov, S. V.; Avouac, J. P.

2015-12-01

The April 2015 Gorkha, Nepal (Mw 7.8) earthquake ruptured the front of Himalaya thrust belt, causing more than 9,000 fatalities. 17 days after the main event, a large aftershock (Mw 7.2) ruptured to down-dip and east of the main rupture area. To investigate the kinematic rupture process of this earthquake sequence, we explored linear and non-linear inversion techniques using a variety of datasets including teleseismic, high rate and conventional GPS, InSAR interferograms and pixel-offsets. InSAR interferograms from ALOS-2, RADARSAT-2 and Sentinel-1a satellites are used in the joint inversion. The main event is characterized by unilateral rupture extending along strike approximately 70 km to the southeast and 40 km along dip direction. The rupture velocity is well resolved to be lie between 2.8 and 3.0 km/s, which is consistent with back-projection results. An emergent initial phase is observed in teleseismic body wave records, which is consistent with a narrow area of rupture initiation near the hypocenter. The rupture mode of the main event is pulse like. The aftershock ruptured down-dip to the northeast of the main event rupture area. The aftershock rupture area is compact and contained within 40 km of its hypocenter. In contrast to the main event, teleseismic body wave records of the aftershock suggest an abrupt initial phase, which is consistent with a crack like rupture mode. The locations of most of the aftershocks (small and large) surround the rupture area of the main shock with little, if any, spatial overlap.

Influence of morphology and hemodynamic factors on rupture of multiple intracranial aneurysms: matched-pairs of ruptured-unruptured aneurysms located unilaterally on the anterior circulation.

PubMed

Zhang, Ying; Yang, Xinjian; Wang, Yang; Liu, Jian; Li, Chuanhui; Jing, Linkai; Wang, Shengzhang; Li, Haiyun

2014-12-31

The authors evaluated the impact of morphological and hemodynamic factors on the rupture of matched-pairs of ruptured-unruptured intracranial aneurysms on one patient's ipsilateral anterior circulation with 3D reconstruction model and computational fluid dynamic method simulation. 20 patients with intracranial aneurysms pairs on the same-side of anterior circulation but with different rupture status were retrospectively collected. Each pair was divided into ruptured-unruptured group. Patient-specific models based on their 3D-DSA images were constructed and analyzed. The relative locations, morphologic and hemodynamic factors of these two groups were compared. There was no significant difference in the relative bleeding location. The morphological factors analysis found that the ruptured aneurysms more often had irregular shape and had significantly higher maximum height and aspect ratio. The hemodynamic factors analysis found lower minimum wall shear stress (WSSmin) and more low-wall shear stress-area (LSA) in the ruptured aneurysms than that of the unruptured ones. The ruptured aneurysms more often had WSSmin on the dome. Intracranial aneurysms pairs with different rupture status on unilateral side of anterior circulation may be a good disease model to investigate possible characteristics linked to rupture independent of patient characteristics. Irregular shape, larger size, higher aspect ratio, lower WSSmin and more LSA may indicate a higher risk for their rupture.

Dynamic rheology of food protein networks

USDA-ARS?s Scientific Manuscript database

Small amplitude oscillatory shear analyses of samples containing protein are useful for determining the nature of the protein matrix without damaging it. Elastic modulus, viscous modulus, and loss tangent (the ratio of viscous modulus to elastic modulus) give information on the strength of the netw...

Characterize kinematic rupture history of large earthquakes with Multiple Haskell sources

NASA Astrophysics Data System (ADS)

Jia, Z.; Zhan, Z.

2017-12-01

Earthquakes are often regarded as continuous rupture along a single fault, but the occurrence of complex large events involving multiple faults and dynamic triggering challenges this view. Such rupture complexities cause difficulties in existing finite fault inversion algorithms, because they rely on specific parameterizations and regularizations to obtain physically meaningful solutions. Furthermore, it is difficult to assess reliability and uncertainty of obtained rupture models. Here we develop a Multi-Haskell Source (MHS) method to estimate rupture process of large earthquakes as a series of sub-events of varying location, timing and directivity. Each sub-event is characterized by a Haskell rupture model with uniform dislocation and constant unilateral rupture velocity. This flexible yet simple source parameterization allows us to constrain first-order rupture complexity of large earthquakes robustly. Additionally, relatively few parameters in the inverse problem yields improved uncertainty analysis based on Markov chain Monte Carlo sampling in a Bayesian framework. Synthetic tests and application of MHS method on real earthquakes show that our method can capture major features of large earthquake rupture process, and provide information for more detailed rupture history analysis.

Rupture rate and patterns of shell failure with the McGhan Style 153 double-lumen breast implant.

PubMed

Neaman, Keith C; Albert, Mark; Hammond, Dennis C

2011-01-01

In 2005, the McGhan Style 153 double-lumen breast implant was removed from the market secondary to a higher rupture rate when contrasted with other implants in the Core Study group. The high rupture rate was attributed to the development of a posterior tear in the shell where the inner implant is bonded to the posterior wall of the device. The purpose of this study was to report the existing rupture rate and describe the apparent mechanism of failure in the Style 153 double-lumen breast implant. Ninety-seven patients (157 implants) who received the McGhan Style 153 double-lumen breast implant by the senior author were reviewed. Intraoperative observations and photographic images of ruptured implants were reviewed and characterized based on severity and location of implant rupture. With a mean length of follow-up of greater than 6 years (82 months), the rupture rate was 19.1 percent per implant. Physical examination (60 percent) was the most common method of rupture detection. Ruptures tended to occur in the marginal aspect (63 percent) of the implant. Only three ruptures occurred secondary to a disruption of the inner bladder from the posterior portion of the implant. The rupture rate of the Style 153 double-lumen breast implant is higher than previously thought, with a rate of 19.1 percent. A majority of ruptures occurred in the peripheral aspects of the implant. It is postulated that these ruptures were likely secondary to fold flaws that led to failure of the implant shell.

Multiple tendon ruptures of unknown etiology.

PubMed

Axibal, Derek P; Anderson, John G

2013-10-01

Tendon ruptures are common findings in foot and ankle practice. The etiology of tendon ruptures tends to be multifactorial-usually due to a combination of trauma, effects of systemic diseases, adverse effects of medications, and obesity. We present an unusual case of right Achilles tendinitis, left Achilles tendon rupture, bilateral peroneus longus tendon rupture, and left peroneus brevis tendon rupture of unknown etiology. This case report highlights the need for research for other possible, lesser known etiologies of tendon pathology. Therapeutic, Level IV, Case Study.

Geologic Inheritance and Earthquake Rupture Processes: The 1905 M ≥ 8 Tsetserleg-Bulnay Strike-Slip Earthquake Sequence, Mongolia

NASA Astrophysics Data System (ADS)

Choi, Jin-Hyuck; Klinger, Yann; Ferry, Matthieu; Ritz, Jean-François; Kurtz, Robin; Rizza, Magali; Bollinger, Laurent; Davaasambuu, Battogtokh; Tsend-Ayush, Nyambayar; Demberel, Sodnomsambuu

2018-02-01

In 1905, 14 days apart, two M 8 continental strike-slip earthquakes, the Tsetserleg and Bulnay earthquakes, occurred on the Bulnay fault system, in Mongolia. Together, they ruptured four individual faults, with a total length of 676 km. Using submetric optical satellite images "Pleiades" with ground resolution of 0.5 m, complemented by field observation, we mapped in detail the entire surface rupture associated with this earthquake sequence. Surface rupture along the main Bulnay fault is 388 km in length, striking nearly E-W. The rupture is formed by a series of fault segments that are 29 km long on average, separated by geometric discontinuities. Although there is a difference of about 2 m in the average slip between the western and eastern parts of the Bulnay rupture, along-fault slip variations are overall limited, resulting in a smooth slip distribution, except for local slip deficit at segment boundaries. We show that damage, including short branches and secondary faulting, associated with the rupture propagation, occurred significantly more often along the western part of the Bulnay rupture, while the eastern part of the rupture appears more localized and thus possibly structurally simpler. Eventually, the difference of slip between the western and eastern parts of the rupture is attributed to this difference of rupture localization, associated at first order with a lateral change in the local geology. Damage associated to rupture branching appears to be located asymmetrically along the extensional side of the strike-slip rupture and shows a strong dependence on structural geologic inheritance.

Interconversion of dynamic modulus to creep compliance and relaxation modulus : numerical modeling and laboratory validation - final report.

DOT National Transportation Integrated Search

2016-09-01

Viscoelastic material functions such as time domain functions, such as, relaxation modulus and creep compliance, : or frequency domain function, such as, complex modulus can be used to characterize the linear viscoelastic behavior : of asphalt concre...

Heroin Use Is Associated with Ruptured Saccular Aneurysms.

PubMed

Can, Anil; Castro, Victor M; Ozdemir, Yildirim H; Dagen, Sarajune; Dligach, Dmitriy; Finan, Sean; Yu, Sheng; Gainer, Vivian; Shadick, Nancy A; Savova, Guergana; Murphy, Shawn; Cai, Tianxi; Weiss, Scott T; Du, Rose

2017-11-04

While cocaine use is thought to be associated with aneurysmal rupture, it is not known whether heroin use increases the risk of rupture in patients with non-mycotic saccular aneurysms. Our goal was to investigate the association between heroin and cocaine use and the rupture of saccular non-mycotic aneurysms. The medical records of 4701 patients with 6411 intracranial aneurysms, including 1201 prospective patients, diagnosed at the Brigham and Women's Hospital and Massachusetts General Hospital between 1990 and 2016 were reviewed and analyzed. Patients were separated into ruptured and non-ruptured groups. Univariable and multivariable logistic regression analyses were performed to determine the association between heroin, cocaine, and methadone use and the presence of ruptured intracranial aneurysms. In multivariable analysis, current heroin use was significantly associated with rupture status (OR 3.23, 95% CI 1.33-7.83) whereas former heroin use (with and without methadone replacement therapy), and current and former cocaine use were not significantly associated with intracranial aneurysm rupture. In the present study, heroin rather than cocaine use is significantly associated with intracranial aneurysm rupture in patients with non-mycotic saccular cerebral aneurysms, emphasizing the possible role of heroin in the pathophysiology of aneurysm rupture and the importance of heroin cessation in patients harboring unruptured intracranial aneurysms.

Describing Soils: Calibration Tool for Teaching Soil Rupture Resistance

ERIC Educational Resources Information Center

Seybold, C. A.; Harms, D. S.; Grossman, R. B.

2009-01-01

Rupture resistance is a measure of the strength of a soil to withstand an applied stress or resist deformation. In soil survey, during routine soil descriptions, rupture resistance is described for each horizon or layer in the soil profile. The lower portion of the rupture resistance classes are assigned based on rupture between thumb and…

Mathematical modeling and numerical simulation of unilateral dynamic rupture propagation along very-long reverse faults

NASA Astrophysics Data System (ADS)

Hirano, S.

2017-12-01

For some great earthquakes, dynamic rupture propagates unilaterally along a horizontal direction of very-long reverse faults (e.g., the Mw9.1 Sumatra earthquake in 2004, the Mw8.0 Wenchuan earthquake in 2008, and the Mw8.8 Maule earthquake in 2010, etc.). It seems that barriers or creeping sections may not lay along the opposite region of the co-seismically ruptured direction. In fact, in the case of Sumatra, the Mw8.6 earthquake occurred in the opposite region only three months after the mainshock. Mechanism of unilateral mode-II rupture along a material interface has been investigated theoretically and numerically. For mode-II rupture propagating along a material interface, an analytical solution implies that co-seismic stress perturbation depends on the rupture direction (Weertman, 1980 JGR; Hirano & Yamashita, 2016 BSSA), and numerical modeling of plastic yielding contributes to simulating the unilateral rupture (DeDonteny et al., 2011 JGR). However, mode-III rupture may dominate for the very-long reverse faults, and it can be shown that stress perturbation due to mode-III rupture does not depend on the rupture direction. Hence, an effect of the material interface is insufficient to understand the mechanism of unilateral rupture along the very-long reverse faults. In this study, I consider a two-dimensional bimaterial system with interfacial dynamic mode-III rupture under an obliquely pre-stressed configuration (i.e., the maximum shear direction of the background stress is inclined from the interfacial fault). First, I derived an analytical solution of regularized elastic stress field around a steady-state interfacial slip pulse using the method of Rice et al. (2005 BSSA). Then I found that the total stress, which is the sum of the background stress and co-seismic stress perturbation, depends on the rupture direction even in the mode-III case. Second, I executed a finite difference numerical simulation with a plastic yielding model of Andrews (1978 JGR; 2005 JGR) and succeeded in a simulation of unilateral rupture propagation in some parameter ranges (see figure). This unilateral rupture might be caused by energy dissipation due to the plastic yielding process that concentrates in the vicinity of only one rupture tip depending on the rupture direction.

Geological structures control on earthquake ruptures: The Mw7.7, 2013, Balochistan earthquake, Pakistan

NASA Astrophysics Data System (ADS)

Vallage, A.; Klinger, Y.; Lacassin, R.; Delorme, A.; Pierrot-Deseilligny, M.

2016-10-01

The 2013 Mw7.7 Balochistan earthquake, Pakistan, ruptured the Hoshab fault. Left-lateral motion dominated the deformation pattern, although significant vertical motion is found along the southern part of the rupture. Correlation of high-resolution (2.5 m) optical satellite images provided horizontal displacement along the entire rupture. In parallel, we mapped the ground rupture geometry at 1:500 scale. We show that the azimuth of the ground rupture distributes mainly between two directions, N216° and N259°. The direction N216° matches the direction of preexisting geologic structures resulting from penetrative deformation caused by the nearby Makran subduction. Hence, during a significant part of its rupture, the 2013 Balochistan rupture kept switching between a long-term fault front and secondary branches, in which existence and direction are related to the compressional context. It shows unambiguous direct interactions between different preexisting geologic structures, regional stress, and dynamic-rupture stress, which controlled earthquake propagation path.

Laparoscopic uterine surgery as a risk factor for uterine rupture during pregnancy.

PubMed

Chao, An-Shine; Chang, Yao-Lung; Yang, Lan-Yan; Chao, Angel; Chang, Wei-Yang; Su, Sheng-Yuan; Wang, Chin-Jung

2018-01-01

The incidence of uterine rupture through a previous cesarean scar (CS) is declining as a result of a lower parity and fewer options for vaginal birth after cesarean. However, uterine ruptures attributable to other causes that traumatize the myometrium are on the rise. To determine whether changes in the causes of uterine rupture had occurred in recent years, we retrospective retrieved the clinical records of all singletons with uterine rupture observed in the delivery room of a Taiwanese tertiary obstetric center over a 15-year period. The overall uterine rupture rate was 3.8 per 10,000 deliveries. A total of 22 cases in 20 women (with two of them experiencing two episodes). Seven uterine ruptures occurred through a previous cesarean scar (CS ruptures, 32%), 13 through a non-cesarean scar (non-CS ruptures, 59%), whereas the remaining two (9%) were in women who did not previously undergo any surgery. All of the 13 non-CS ruptures were identified in women with a history of laparoscopic procedures to the uterus. Specifically, 10 (76%) occurred after a previous laparoscopic myomectomy, one (8%) following a hysteroscopic myomectomy, and two (16%) after a laparoscopic wedge resection of cornual ectopic pregnancy. Severe bleeding (blood loss >1500 mL) requiring transfusions was more frequent in women who experienced non-CS compared with CS ruptures (10 versus 1 case, respectively, P = 0.024). Patients with a history of endoscopic uterine surgery should be aware of uterine rupture during pregnancy.

Laparoscopic uterine surgery as a risk factor for uterine rupture during pregnancy

PubMed Central

Chao, An-Shine; Chang, Yao-Lung; Yang, Lan-Yan; Chao, Angel; Chang, Wei-Yang; Su, Sheng-Yuan

2018-01-01

The incidence of uterine rupture through a previous cesarean scar (CS) is declining as a result of a lower parity and fewer options for vaginal birth after cesarean. However, uterine ruptures attributable to other causes that traumatize the myometrium are on the rise. To determine whether changes in the causes of uterine rupture had occurred in recent years, we retrospective retrieved the clinical records of all singletons with uterine rupture observed in the delivery room of a Taiwanese tertiary obstetric center over a 15-year period. The overall uterine rupture rate was 3.8 per 10,000 deliveries. A total of 22 cases in 20 women (with two of them experiencing two episodes). Seven uterine ruptures occurred through a previous cesarean scar (CS ruptures, 32%), 13 through a non-cesarean scar (non-CS ruptures, 59%), whereas the remaining two (9%) were in women who did not previously undergo any surgery. All of the 13 non-CS ruptures were identified in women with a history of laparoscopic procedures to the uterus. Specifically, 10 (76%) occurred after a previous laparoscopic myomectomy, one (8%) following a hysteroscopic myomectomy, and two (16%) after a laparoscopic wedge resection of cornual ectopic pregnancy. Severe bleeding (blood loss >1500 mL) requiring transfusions was more frequent in women who experienced non-CS compared with CS ruptures (10 versus 1 case, respectively, P = 0.024). Patients with a history of endoscopic uterine surgery should be aware of uterine rupture during pregnancy. PMID:29787604

Fault zones ruptured during the early 2014 Cephalonia Island (Ionian Sea, Western Greece) earthquakes (January 26 and February 3, Mw 6.0) based on the associated co-seismic surface ruptures

NASA Astrophysics Data System (ADS)

Lekkas, Efthymios L.; Mavroulis, Spyridon D.

2016-01-01

The early 2014 Cephalonia Island (Ionian Sea, Western Greece) earthquake sequence comprised two main shocks with almost the same magnitude (moment magnitude (Mw) 6.0) occurring successively within a short time (January 26 and February 3) and space (Paliki peninsula in Western Cephalonia) interval. Εach earthquake was induced by the rupture of a different pre-existing onshore active fault zone and produced different co-seismic surface rupture zones. Co-seismic surface rupture structures were predominantly strike-slip-related structures including V-shaped conjugate surface ruptures, dextral and sinistral strike-slip surface ruptures, restraining and releasing bends, Riedel structures ( R, R', P, T), small-scale bookshelf faulting, and flower structures. An extensional component was present across surface rupture zones resulting in ground openings (sinkholes), small-scale grabens, and co-seismic dip-slip (normal) displacements. A compressional component was also present across surface rupture zones resulting in co-seismic dip-slip (reverse) displacements. From the comparison of our field geological observations with already published surface deformation measurements by DInSAR Interferometry, it is concluded that there is a strong correlation among the surface rupture zones, the ruptured active fault zones, and the detected displacement discontinuities in Paliki peninsula.

Penile fracture: a rare case of simultaneous rupture of the one corpus cavernosum and complete urethral rupture.

PubMed

Nale, Djordje; Bojanić, Nebojša; Nikić, Predrag

2015-01-01

Penile fracture is a traumatic rupture of tunica albuginea and the tumescent corpora cavernosa due to the nonphysiological bending of the penile shaft, presenting with or without rupture of corpus pongiosum and urethra. The incidence of concomitant injury of the urethra is 0-38%. Complete urethral rupture is rare, but it is almost always associated with bilateral corporeal injury. We presented a patient with complete urethral rupture, and rupture of the right cavernous body. According to the available literature, this case is extremely rare. Fracture of the penis is relatively uncommon and is considered a urologic emergency. Prompt surgical explo- ration and repair can preserve erectile and voiding function.

Linguine sign in musculoskeletal imaging: calf silicone implant rupture.

PubMed

Duryea, Dennis; Petscavage-Thomas, Jonelle; Frauenhoffer, Elizabeth E; Walker, Eric A

2015-08-01

Imaging findings of breast silicone implant rupture are well described in the literature. On MRI, the linguine sign indicates intracapsular rupture, while the presence of silicone particles outside the fibrous capsule indicates extracapsular rupture. The linguine sign is described as the thin, wavy hypodense wall of the implant within the hyperintense silicone on T2-weighted images indicative of rupture of the implant within the naturally formed fibrous capsule. Hyperintense T2 signal outside of the fibrous capsule is indicative of an extracapsular rupture with silicone granuloma formation. We present a rare case of a patient with a silicone calf implant rupture and discuss the MRI findings associated with this condition.

Distal Biceps Tendon Rupture

DTIC Science & Technology

2010-06-01

Distal Biceps Tendon Rupture Military Medicine Radiology Corner, 2006 Radiology Corner Distal Biceps Tendon Rupture Contributors: CPT Michael...treatment of a 56-year-old man with complete rupture of the distal biceps tendon . The mechanism of injury, symptoms, and findings at physical...be used in pre-operative planning. Introduction Rupture of the distal biceps tendon is a relatively uncommon injury, but delayed diagnosis may

A constrained modulus reconstruction technique for breast cancer assessment.

PubMed

Samani, A; Bishop, J; Plewes, D B

2001-09-01

A reconstruction technique for breast tissue elasticity modulus is described. This technique assumes that the geometry of normal and suspicious tissues is available from a contrast-enhanced magnetic resonance image. Furthermore, it is assumed that the modulus is constant throughout each tissue volume. The technique, which uses quasi-static strain data, is iterative where each iteration involves modulus updating followed by stress calculation. Breast mechanical stimulation is assumed to be done by two compressional rigid plates. As a result, stress is calculated using the finite element method based on the well-controlled boundary conditions of the compression plates. Using the calculated stress and the measured strain, modulus updating is done element-by-element based on Hooke's law. Breast tissue modulus reconstruction using simulated data and phantom modulus reconstruction using experimental data indicate that the technique is robust.

Nondestructive Measurement of Dynamic Modulus for Cellulose Nanofibril Films

Treesearch

Yan Qing; Robert J. Ross; Zhiyong Cai; Yiqiang Wu

2013-01-01

Nondestructive evaluation of cellulose nanofibril (CNF) films was performed using cantilever beam vibration (CBV) and acoustic methods to measure dynamic modulus. Static modulus was tested using tensile tension method. Correlation analysis shows the data measured by CBV has little linear relationship with static modulus, possessing a correlation coefficient (R

Clinical recovery of two hip adductor longus ruptures: a case-report of a soccer player

PubMed Central

2013-01-01

Background Non-operative treatment of acute hip adductor longus ruptures in athletes has been described in the literature. However, very limited information concerning the recovery of this type of injury exists. This case represented a unique possibility to study the recovery of two acute adductor longus ruptures, using novel, reliable and validated assessment methods. Case presentation A 22-year old male soccer player (Caucasian) sustained two subsequent acute adductor longus ruptures, one in each leg. The injuries occurred 10 months apart, and were treated non-surgically in both situations. He was evaluated using hip-strength assessments, self-report and ultrasonography until complete muscle-strength recovery of the hip adductors had occurred. The player was able to participate in a full soccer training session without experiencing pain 15 weeks after the first rupture, and 12 weeks after the second rupture. Full hip adductor muscle-strength recovery was obtained 52 weeks after the first rupture and 10 weeks after the second rupture. The adductor longus injuries, as verified by initial ultrasonography (10 days post-injury), showed evidence of a complete tendon rupture in both cases, with an almost identical imaging appearance. It was only at 6 and 10 weeks ultrasonographic follow-up that the first rupture was found to include a larger anatomical area than the second rupture. Conclusion From this case we can conclude that two apparently similar hip adductor longus ruptures, verified by initial ultrasonography (10 days post-injury), can have very different hip adductor strength recovery times. Assessment of adductor strength recovery may therefore in the future be a useful and important additional measure for determining when soccer players with hip adductor longus ruptures can return safely to play. PMID:23693119

Spontaneous rupture of splenic artery aneurysm in pregnancy: a case report.

PubMed

Gourgiotis, S; Alfaras, P; Salemis, N S

2008-01-01

Splenic artery aneurysms (SAA) occur predominantly in women, and the majority of them are asymptomatic until rupture. Over half of those that rupture occur during pregnancy. Spontaneously ruptured SAA during pregnancy is always a life-threatening surgical entity for both the mother and the fetus. We report the case of a 29-year-old woman at 34 weeks' gestation with spontaneous rupture of SAA who underwent emergency exploratory laparotomy and splenectomy. This case illustrates the need to consider ruptured SAA as part of important differential diagnosis in haemodynamically unstable pregnant women.

Creep-rupture behavior of candidate Stirling engine iron supperalloys in high-pressure hydrogen. Volume 2: Hydrogen creep-rupture behavior

NASA Technical Reports Server (NTRS)

Bhattacharyya, S.; Peterman, W.; Hales, C.

1984-01-01

The creep rupture behavior of nine iron base and one cobalt base candidate Stirling engine alloys is evaluated. Rupture life, minimum creep rate, and time to 1% strain data are analyzed. The 3500 h rupture life stress and stress to obtain 1% strain in 3500 h are also estimated.

A comparison of pre-dropout and temporary rupture sessions in psychotherapy.

PubMed

Gülüm, I Volkan; Soygüt, Gonca; Safran, Jeremy D

2016-11-15

Although numerous studies have investigated the relationship between the therapeutic alliance and dropout, most have focused on the relationship between alliance quality and psychotherapy outcomes. To compare sessions with therapeutic alliance ruptures and two sessions prior to treatment dropout (pre-dropout) in terms of rupture subtypes, psychotherapists' behavior, attitudes, and session content. We implemented quantitative methods to select the sessions and qualitative methods to analyze them. We analyzed 16 temporary rupture sessions from 12 therapist-patient dyads and 16 pre-dropout sessions from 8 different therapist-patient dyads. The sessions originate from clinical psychology Master's or Doctoral students under supervision in either cognitive behavioral or schema therapy. Pre-dropout sessions were considered unrepaired rupture sessions while rupture sessions were subsequently repaired. Results revealed apparent differences and similarities between the session types in positive and negative psychotherapist behaviors, content intensity, and the type and frequency of ruptures. We explored three new rupture subtypes: attributing positive developments to other sources, indirect speech, and sarcastic hostility. A striking implication is that the frequency of positive and negative psychotherapist behaviors, ruptures, and session content is more likely to decrease in the pre-dropout sessions than in the temporary rupture sessions.

Surface fault rupture during the Mw 7.8 Kaikoura earthquake, New Zealand, with specific comment on the Kekerengu Fault - one of the country's fastest slipping onland active faults

NASA Astrophysics Data System (ADS)

Van Dissen, Russ; Little, Tim

2017-04-01

The Mw 7.8 Kaikoura earthquake of 14 November, 2016 (NZDT) was a complex event. It involved ground-surface (or seafloor) fault rupture on at least a dozen onland or offshore faults, and subsurface rupture on a handful of additional faults. Most of the surface ruptures involved previously known (or suspected) active faults, as well as surface rupture on at least two hitherto unrecognised active faults. The southwest to northeast extent of surface fault rupture, as generalised by two straight-line segments, is approximately 180 km, though this is a minimum for the collective length of surface rupture due to multiple overlapping faults with various orientations. Surface rupture displacements on specific faults involved in the Kaikoura Earthquake span approximately two orders of magnitude. For example, maximum surface displacement on the Heaver's Creek Fault is cm- to dm-scale in size; whereas, maximum surface displacement on the nearby Kekerengu Fault is approximately 10-12 m (predominantly in a dextral sense). The Kekerengu Fault has a Late Pleistocene slip-rate rate of 20-26 mm/yr, and is possibly the second fastest slipping onland fault in New Zealand, behind the Alpine Fault. Located in the northeastern South Island of New Zealand, the Kekerengu Fault - along with the Hope Fault to the southwest and the Needles Fault offshore to the northeast - comprise the fastest slipping elements of the Pacific-Australian plate boundary in this part of the country. In January 2016 (about ten months prior to the Kaikoura earthquake) three paleo-earthquake investigation trenches were excavated across pronounced traces of the Kekerengu Fault at two locations. These were the first such trenches dug and evaluated across the fault. All three trenches displayed abundant evidence of past surface fault ruptures (three surface ruptures in the last approximately 1,200 years, four now including the 2016 rupture). An interesting aspect of the 2016 rupture is that two of the trenches received surface fault rupture, and are now dextrally offset by about 9 m, while the third trench did not have any 2016 surface rupture pass through it. In this instance, ground-surface rupture along this trace of the fault died out within tens of metres of the trench. Another salient aspect of the Kaikoura earthquake is that the determined (or estimated) recurrence intervals of the faults that ruptured the ground surface vary by an order of magnitude or more. This strongly implies that the ensemble of faults that ruptured with the Kekerengu Fault in the 2016 earthquake has not always been the same for past earthquakes. Possible reasons for this could include the state of stress at the time of a specific earthquake, the direction of rupture propagation, and whether or not rupture on one fault system cascades into rupture on another as is suspected to have happened in the Kaikoura earthquake.

Surface Rupture Characteristics and Rupture Mechanics of the Yushu Earthquake (Ms7.1), 14/04/2010

NASA Astrophysics Data System (ADS)

Pan, J.; Li, H.; Xu, Z.; Li, N.; Wu, F.; Guo, R.; Zhang, W.

2010-12-01

On April 14th 2010, a disastrous earthquake (Ms 7.1) struck Yushu County, Qinghai Province, China, killing thousands of people. This earthquake occurred as a result of sinistral strike-slip faulting on the western segment of the Xianshuihe Fault zone in eastern Tibetan Plateau. Our group conducted scientific investigation in the field on co-seismic surface rupture and active tectonics in the epicenter area immediately after the earthquake. Here, we introduce our preliminary results on the surface ruptures and rupture mechanics of the Yushu Earthquake. The surface rupture zone of Yushu earthquake, which is about 49 km-long, consists of 3 discontinuous left stepping rupture segments, which are 19 km, 22 km, and about 8 km, respectively, from west to east. Each segment consists of a series of right stepping en-echelon branch ruptures. The branch ruptures consist of interphase push-up and tension fissures or simply en-echelon tension fissures. The co-seismic displacements had been surveyed with a total station in detail on landmarks such as rivers, gullies, roads, farmlands, wire poles, and fences. The maximum offset measured is 2.3m, located near the Guoyangyansongduo Village. There are 3 offset peaks along the rupture zone corresponding to the 3 segments of the surface rupture zone. The maximum offsets in the west, central, and east segment rupture zones are 1.4m, 2.3m, and 1.6m respectively. The surface rupture zone of Yushu earthquake strikes in a 310°NW direction. The fault plane dips to the northeast and the dip angle is about 81°. The rupture zone is developed in transtension setting. Tension normal fault developed during the sinistral strike-slip process of the fault. The valley west of Yushu City and the Longbao Lake are both pull-apart basins formed during the transtension activity of the fault.

Long-Period Ground Motion due to Near-Shear Earthquake Ruptures

NASA Astrophysics Data System (ADS)

Koketsu, K.; Yokota, Y.; Hikima, K.

2010-12-01

Long-period ground motion has become an increasingly important consideration because of the recent rapid increase in the number of large-scale structures, such as high-rise buildings and large oil storage tanks. Large subduction-zone earthquakes and moderate to large crustal earthquakes can generate far-source long-period ground motions in distant sedimentary basins with the help of path effects. Near-fault long-period ground motions are generated, for the most part, by the source effects of forward rupture directivity (Koketsu and Miyake, 2008). This rupture directivity effect is the maximum in the direction of fault rupture when a rupture velocity is nearly equal to shear wave velocity around a source fault (Dunham and Archuleta, 2005). The near-shear rupture was found to occur during the 2008 Mw 7.9 Wenchuan earthquake at the eastern edge of the Tibetan plateau (Koketsu et al., 2010). The variance of waveform residuals in a joint inversion of teleseismic and strong motion data was the minimum when we adopted a rupture velocity of 2.8 km/s, which is close to the shear wave velocity of 2.6 km/s around the hypocenter. We also found near-shear rupture during the 2010 Mw 6.9 Yushu earthquake (Yokota et al., 2010). The optimum rupture velocity for an inversion of teleseismic data is 3.5 km/s, which is almost equal to the shear wave velocity around the hypocenter. Since, in addition, supershear rupture was found during the 2001 Mw 7.8 Central Kunlun earthquake (Bouchon and Vallee, 2003), such fast earthquake rupture can be a characteristic of the eastern Tibetan plateau. Huge damage in Yingxiu and Beichuan from the 2008 Wenchuan earthquake and damage heavier than expected in the county seat of Yushu from the medium-sized Yushu earthquake can be attributed to the maximum rupture directivity effect in the rupture direction due to near-shear earthquake ruptures.

Aneurysm Morphology and Prediction of Rupture: An International Study of Unruptured Intracranial Aneurysms Analysis.

PubMed

Mocco, J; Brown, Robert D; Torner, James C; Capuano, Ana W; Fargen, Kyle M; Raghavan, Madhavan L; Piepgras, David G; Meissner, Irene; Huston, John

2018-04-01

There are conflicting data between natural history studies suggesting a very low risk of rupture for small, unruptured intracranial aneurysms and retrospective studies that have identified a much higher frequency of small, ruptured aneurysms than expected. To use the prospective International Study of Unruptured Intracranial Aneurysms cohort to identify morphological characteristics predictive of unruptured intracranial aneurysm rupture. A case-control design was used to analyze morphological characteristics associated with aneurysm rupture in the International Study of Unruptured Intracranial Aneurysms database. Fifty-seven patients with ruptured aneurysms during follow-up were matched (by size and location) with 198 patients with unruptured intracranial aneurysms without rupture during follow-up. Twelve morphological metrics were measured from cerebral angiograms in a blinded fashion. Perpendicular height (P = .008) and size ratio (ratio of maximum diameter to the parent vessel diameter; P = .01) were predictors of aneurysm rupture on univariate analysis. Aspect ratio, daughter sacs, multiple lobes, aneurysm angle, neck diameter, parent vessel diameter, and calculated aneurysm volume were not statistically significant predictors of rupture. On multivariate analysis, perpendicular height was the only significant predictor of rupture (Chi-square 7.1, P-value .008). This study underscores the importance of other morphological factors, such as perpendicular height and size ratio, that may influence unruptured intracranial aneurysm rupture risk in addition to greatest diameter and anterior vs posterior location.

Historic Surface Rupture Informing Probabilistic Fault Displacement Analysis: New Zealand Case Studies

NASA Astrophysics Data System (ADS)

Villamor, P.; Litchfield, N. J.; Van Dissen, R. J.; Langridge, R.; Berryman, K. R.; Baize, S.

2016-12-01

Surface rupture associated with the 2010 Mw7.1 Darfield Earthquake (South Island, New Zealand) was extremely well documented, thanks to an immediate field mapping response and the acquisition of LiDAR data within days of the event. With respect to informing Probabilistic Fault Displacement Analysis (PFDHA) the main insights and outcomes from this rupture through Quaternary gravel are: 1) significant distributed deformation either side of the main trace (30 to 300 m wide deformation zone) and how the deformation is distributed away from the main trace; 2) a thorough analysis of uncertainty of the displacement measures obtained using the LIDAR data and repeated measurements from several scientists; and 3) the short surface rupture length for the reported magnitude, resulting from complex fault rupture with 5-6 reverse and strike-slip strands, most of which had no surface rupture. While the 2010 event is extremely well documented and will be an excellent case to add to the Surface Rupture during Earthquakes database (SURE), other NZ historical earthquakes that are not so well documented, but can provide important information for PFDHA. New Zealand has experienced about 10 historical surface fault ruptures since 1848, comprising ruptures on strike-slip, reverse and normal faults. Mw associated with these ruptures ranges between 6.3 and 8.1. From these ruptures we observed that the surface expression of deformation can be influenced by: fault maturity; the type of Quaternary sedimentary cover; fault history (e.g., influence of inversion tectonics, flexural slip); fault complexity; and primary versus secondary rupture. Other recent >Mw 6.6 earthquakes post-2010 that did not rupture the ground surface have been documented with InSAR and can inform Mw thresholds for surface fault rupture. It will be important to capture all this information and that of similar events worldwide to inform the SURE database and ultimately PFDHA.

Open versus endovascular repair of ruptured abdominal aortic aneurysms: What have we learned after more than 2 decades of ruptured endovascular aneurysm repair?

PubMed

Robinson, William P

2017-12-01

Ruptured abdominal aortic aneurysm is one of the most difficult clinical problems in surgical practice, with extraordinarily high morbidity and mortality. During the past 23 years, the literature has become replete with reports regarding ruptured endovascular aneurysm repair. A variety of study designs and databases have been utilized to compare ruptured endovascular aneurysm repair and open surgical repair for ruptured abdominal aortic aneurysm and studies of various designs from different databases have yielded vastly different conclusions. It therefore remains controversial whether ruptured endovascular aneurysm repair improves outcomes after ruptured abdominal aortic aneurysm in comparison to open surgical repair. The purpose of this article is to review the best available evidence comparing ruptured endovascular aneurysm repair and open surgical repair of ruptured abdominal aortic aneurysm, including single institution and multi-institutional retrospective observational studies, large national population-based studies, large national registries of prospectively collected data, and randomized controlled clinical trials. This article will analyze the study designs and databases utilized with their attendant strengths and weaknesses to understand the sometimes vastly different conclusions the studies have reached. This article will attempt to integrate the data to distill some of the lessons that have been learned regarding ruptured endovascular aneurysm repair and identify ongoing needs in this field. Copyright © 2017 Elsevier Inc. All rights reserved.

Diagnosis and management of testicular rupture after blunt scrotal trauma: a literature review.

PubMed

Wang, Zhao; Yang, Jin-Rui; Huang, Yu-Meng; Wang, Long; Liu, Long-Fei; Wei, Yong-Bao; Huang, Liang; Zhu, Quan; Zeng, Ming-Qiang; Tang, Zheng-Yan

2016-12-01

Testicular rupture, one of the most common complications in blunt scrotal trauma, is the rupture of tunica albuginea and extrusion of seminiferous tubules. Testicular rupture is more inclined to young men, and injury mechanisms are associated with sports and motor accidents. After history taking and essential physical examination, scrotal ultrasound is the first-line auxiliary examination. MRI is also one of the vital complementary examinations to evaluate testicular rupture after blunt scrotal trauma. Surgical exploration and repair may be necessary when the diagnosis of testicular rupture is definite or suspicious. Postoperative follow-up is to monitor the relief of local symptoms and changes of testicular functions. This review sums up the literatures about testicular rupture after blunt scrotal trauma in recent 16 years and also refers some new advantages and perspectives on diagnosis and management of testicular rupture.

Global catalog of earthquake rupture velocities shows anticorrelation between stress drop and rupture velocity

NASA Astrophysics Data System (ADS)

Chounet, Agnès; Vallée, Martin; Causse, Mathieu; Courboulex, Françoise

2018-05-01

Application of the SCARDEC method provides the apparent source time functions together with seismic moment, depth, and focal mechanism, for most of the recent earthquakes with magnitude larger than 5.6-6. Using this large dataset, we have developed a method to systematically invert for the rupture direction and average rupture velocity Vr, when unilateral rupture propagation dominates. The approach is applied to all the shallow (z < 120 km) earthquakes of the catalog over the 1992-2015 time period. After a careful validation process, rupture properties for a catalog of 96 earthquakes are obtained. The subsequent analysis of this catalog provides several insights about the seismic rupture process. We first report that up-dip ruptures are more abundant than down-dip ruptures for shallow subduction interface earthquakes, which can be understood as a consequence of the material contrast between the slab and the overriding crust. Rupture velocities, which are searched without any a-priori up to the maximal P wave velocity (6000-8000 m/s), are found between 1200 m/s and 4500 m/s. This observation indicates that no earthquakes propagate over long distances with rupture velocity approaching the P wave velocity. Among the 23 ruptures faster than 3100 m/s, we observe both documented supershear ruptures (e.g. the 2001 Kunlun earthquake), and undocumented ruptures that very likely include a supershear phase. We also find that the correlation of Vr with the source duration scaled to the seismic moment (Ts) is very weak. This directly implies that both Ts and Vr are anticorrelated with the stress drop Δσ. This result has implications for the assessment of the peak ground acceleration (PGA) variability. As shown by Causse and Song (2015), an anticorrelation between Δσ and Vr significantly reduces the predicted PGA variability, and brings it closer to the observed variability.

Resolution of alliance ruptures: The special case of animal-assisted psychotherapy.

PubMed

Zilcha-Mano, Sigal

2017-01-01

Many therapists regard alliance ruptures as one of the greatest challenges therapists face in the therapy room. Alliance ruptures has been previously defined as breakdowns in the process of negotiation of treatment tasks and goals and a deterioration in the affective bond between patient and therapist. Alliance ruptures have been found to predict premature termination of treatment and poor treatment outcomes. But ruptures can also present important opportunities for gaining insight and awareness and for facilitating therapeutic change. A process of rupture resolution may lead to beneficial outcomes and serve as a corrective emotional experience. The article describes unique processes of alliance rupture resolution inherent in animal-assisted psychotherapy (AAP). Building on Safran and Muran's model and on clinical examples, the article describes strategies for identifying ruptures in AAP and techniques for repairing them to facilitate a corrective experience in treatment. Implications for clinical practice and future research are discussed.

Real-Time Detection of Rupture Development: Earthquake Early Warning Using P Waves From Growing Ruptures

NASA Astrophysics Data System (ADS)

Kodera, Yuki

2018-01-01

Large earthquakes with long rupture durations emit P wave energy throughout the rupture period. Incorporating late-onset P waves into earthquake early warning (EEW) algorithms could contribute to robust predictions of strong ground motion. Here I describe a technique to detect in real time P waves from growing ruptures to improve the timeliness of an EEW algorithm based on seismic wavefield estimation. The proposed P wave detector, which employs a simple polarization analysis, successfully detected P waves from strong motion generation areas of the 2011 Mw 9.0 Tohoku-oki earthquake rupture. An analysis using 23 large (M ≥ 7) events from Japan confirmed that seismic intensity predictions based on the P wave detector significantly increased lead times without appreciably decreasing the prediction accuracy. P waves from growing ruptures, being one of the fastest carriers of information on ongoing rupture development, have the potential to improve the performance of EEW systems.

Ruptured Tendons in Anabolic-Androgenic Steroid Users: A Cross-Sectional Cohort Study.

PubMed

Kanayama, Gen; DeLuca, James; Meehan, William P; Hudson, James I; Isaacs, Stephanie; Baggish, Aaron; Weiner, Rory; Micheli, Lyle; Pope, Harrison G

2015-11-01

Accumulating case reports have described tendon rupture in men who use anabolic-androgenic steroids (AAS). However, no controlled study has assessed the history of tendon rupture in a large cohort of AAS users and comparison nonusers. Men reporting long-term AAS abuse would report an elevated lifetime incidence of tendon rupture compared with non-AAS-using bodybuilders. Cohort study; Level of evidence, 3. Medical histories were obtained from 142 experienced male bodybuilders aged 35 to 55 years recruited in the course of 2 studies. Of these men, 88 reported at least 2 years of cumulative lifetime AAS use, and 54 reported no history of AAS use. In men reporting a history of tendon rupture, the circumstances of the injury, prodromal symptoms, concomitant drug or alcohol use, and details of current and lifetime AAS use (if applicable) were recorded. Surgical records were obtained for most participants. Nineteen (22%) of the AAS users, but only 3 (6%) of the nonusers, reported at least 1 lifetime tendon rupture. The hazard ratio for a first ruptured tendon in AAS users versus nonusers was 9.0 (95% CI, 2.5-32.3; P < .001). Several men reported 2 or more independent lifetime tendon ruptures. Interestingly, upper-body tendon ruptures occurred exclusively in the AAS group (15 [17%] AAS users vs 0 nonusers; risk difference, 0.17 [95% CI, 0.09-0.25]; P < .001 [hazard ratio not estimable]), whereas there was no significant difference between users and nonusers in risk for lower-body ruptures (6 [7%] AAS users, 3 [6%] nonusers; hazard ratio, 3.1 [95% CI, 0.7-13.8]; P = .13). Of 31 individual tendon ruptures assessed, only 6 (19%) occurred while weightlifting, with the majority occurring during other sports activities. Eight (26%) ruptures followed prodromal symptoms of nonspecific pain in the region. Virtually all ruptures were treated surgically, with complete or near-complete ultimate restoration of function. AAS abusers, compared with otherwise similar bodybuilders, showed a markedly increased risk of tendon ruptures, particularly upper-body tendon rupture. © 2015 The Author(s).

Effects of Reorientation of Graphene Platelets (GPLs) on Young's Modulus of Polymer Composites under Bi-Axial Stretching.

PubMed

Feng, Chuang; Wang, Yu; Yang, Jie

2018-01-07

Effects of bi-axial stretching induced reorientation of graphene platelets (GPLs) on the Young's modulus of GPL/polymer composites is studied by Mori-Tanaka micromechanics model. The dispersion state of the GPLs in polymer matrix is captured by an orientation distribution function (ODF), in which two Euler angles are used to identify the orientation of the GPLs. Compared to uni-axial stretching, the increase of the stretching strain in the second direction enhances the re-alignment of GPL fillers in this direction while it deteriorates the re-alignment of the fillers in the other two directions. Comprehensive parametric study on the effects of the out-of-plane Young's modulus, stretching strain, strain ratio, Poisson's ratio and weight fraction and GPL dimension on the effective Young's moduli of the composites in the three directions are conducted. It is found that the out-of-plane Young's modulus has limited effects on the overall Young's modulus of the composites. The second stretching enhances the Young's modulus in this direction while it decreases the Young's modulus in the other two directions. The results demonstrate the increase of Poisson's ratio is favorable in increasing the Young's modulus of the composites. GPLs with larger diameter-to-thickness ratio have better reinforcing effect on the Young's modulus of GPL/polymer nanocomposites.

Great earthquakes of variable magnitude at the Cascadia subduction zone

USGS Publications Warehouse

Nelson, A.R.; Kelsey, H.M.; Witter, R.C.

2006-01-01

Comparison of histories of great earthquakes and accompanying tsunamis at eight coastal sites suggests plate-boundary ruptures of varying length, implying great earthquakes of variable magnitude at the Cascadia subduction zone. Inference of rupture length relies on degree of overlap on radiocarbon age ranges for earthquakes and tsunamis, and relative amounts of coseismic subsidence and heights of tsunamis. Written records of a tsunami in Japan provide the most conclusive evidence for rupture of much of the plate boundary during the earthquake of 26 January 1700. Cascadia stratigraphic evidence dating from about 1600??cal yr B.P., similar to that for the 1700 earthquake, implies a similarly long rupture with substantial subsidence and a high tsunami. Correlations are consistent with other long ruptures about 1350??cal yr B.P., 2500??cal yr B.P., 3400??cal yr B.P., 3800??cal yr B.P., 4400??cal yr B.P., and 4900??cal yr B.P. A rupture about 700-1100??cal yr B.P. was limited to the northern and central parts of the subduction zone, and a northern rupture about 2900??cal yr B.P. may have been similarly limited. Times of probable short ruptures in southern Cascadia include about 1100??cal yr B.P., 1700??cal yr B.P., 3200??cal yr B.P., 4200??cal yr B.P., 4600??cal yr B.P., and 4700??cal yr B.P. Rupture patterns suggest that the plate boundary in northern Cascadia usually breaks in long ruptures during the greatest earthquakes. Ruptures in southernmost Cascadia vary in length and recurrence intervals more than ruptures in northern Cascadia.

Total rupture of hydatid cyst of liver in to common bile duct: a case report.

PubMed

Robleh, Hassan; Yassine, Fahmi; Driss, Khaiz; Khalid, Elhattabi; Fatima-Zahra, Bensardi; Saad, Berrada; Rachid, Lefriyekh; Abdalaziz, Fadil; Najib, Zerouali Ouariti

2014-01-01

Rupture of hydatid liver cyst into biliary tree is frequent complications that involve the common hepatic duct, lobar biliary branches, the small intrahepatic bile ducts,but rarely rupture into common bile duct. The rupture of hydatid cyst is serious life threating event. The authors are reporting a case of total rupture of hydatid cyst of liver into common bile duct. A 50-year-old male patient who presented with acute cholangitis was diagnosed as a case of totally rupture of hydatid cyst on Abdominal CT Scan. Rupture of hydatid cyst of liver into common bile duct and the gallbladder was confirmed on surgery. Treated by cholecystectomy and T-tube drainage of Common bile duct.

Resilient modulus characteristics of soil subgrade with geopolymer additive in peat

NASA Astrophysics Data System (ADS)

Zain, Nasuhi; Hadiwardoyo, Sigit Pranowo; Rahayu, Wiwik

2017-06-01

Resilient modulus characteristics of peat soil are generally very low with high potential of deformation and low bearing capacity. The efforts to improve the peat subgrade resilient modulus characteristics is required, one among them is by adding the geopolymer additive. Geopolymer was made as an alternative to replace portland cement binder in the concrete mix in order to promote environmentally friendly, low shrinkage value, low creep value, and fire resistant material. The use of geopolymer to improve the mechanical properties of peat as a road construction subgrade, hence it becomes important to identify the effect of geopolymer addition on the resilient modulus characteristics of peat soil. This study investigated the addition of 0% - 20% geopolymer content on peat soil derived from Ogan Komering Ilir, South Sumatera Province. Resilient modulus measurement was performed by using cyclic triaxial test to determine the resilience modulus model as a function of deviator stresses and radial stresses. The test results showed that an increase in radial stresses did not necessarily lead to an increase in modulus resilient, and on the contrary, an increase in deviator stresses led to a decrease in modulus resilient. The addition of geopolymer in peat soil provided an insignificant effect on the increase of resilient modulus value.

Compression-sensitive magnetic resonance elastography

NASA Astrophysics Data System (ADS)

Hirsch, Sebastian; Beyer, Frauke; Guo, Jing; Papazoglou, Sebastian; Tzschaetzsch, Heiko; Braun, Juergen; Sack, Ingolf

2013-08-01

Magnetic resonance elastography (MRE) quantifies the shear modulus of biological tissue to detect disease. Complementary to the shear elastic properties of tissue, the compression modulus may be a clinically useful biomarker because it is sensitive to tissue pressure and poromechanical interactions. In this work, we analyze the capability of MRE to measure volumetric strain and the dynamic bulk modulus (P-wave modulus) at a harmonic drive frequency commonly used in shear-wave-based MRE. Gel phantoms with various densities were created by introducing CO2-filled cavities to establish a compressible effective medium. The dependence of the effective medium's bulk modulus on phantom density was investigated via static compression tests, which confirmed theoretical predictions. The P-wave modulus of three compressible phantoms was calculated from volumetric strain measured by 3D wave-field MRE at 50 Hz drive frequency. The results demonstrate the MRE-derived volumetric strain and P-wave modulus to be sensitive to the compression properties of effective media. Since the reconstruction of the P-wave modulus requires third-order derivatives, noise remains critical, and P-wave moduli are systematically underestimated. Focusing on relative changes in the effective bulk modulus of tissue, compression-sensitive MRE may be useful for the noninvasive detection of diseases involving pathological pressure alterations such as hepatic hypertension or hydrocephalus.

A novel strategy to translate the biomechanical rupture risk of abdominal aortic aneurysms to their equivalent diameter risk: method and retrospective validation.

PubMed

Gasser, T C; Nchimi, A; Swedenborg, J; Roy, J; Sakalihasan, N; Böckler, D; Hyhlik-Dürr, A

2014-03-01

To translate the individual abdominal aortic aneurysm (AAA) patient's biomechanical rupture risk profile to risk-equivalent diameters, and to retrospectively test their predictability in ruptured and non-ruptured aneurysms. Biomechanical parameters of ruptured and non-ruptured AAAs were retrospectively evaluated in a multicenter study. General patient data and high resolution computer tomography angiography (CTA) images from 203 non-ruptured and 40 ruptured aneurysmal infrarenal aortas. Three-dimensional AAA geometries were semi-automatically derived from CTA images. Finite element (FE) models were used to predict peak wall stress (PWS) and peak wall rupture index (PWRI) according to the individual anatomy, gender, blood pressure, intra-luminal thrombus (ILT) morphology, and relative aneurysm expansion. Average PWS diameter and PWRI diameter responses were evaluated, which allowed for the PWS equivalent and PWRI equivalent diameters for any individual aneurysm to be defined. PWS increased linearly and PWRI exponentially with respect to maximum AAA diameter. A size-adjusted analysis showed that PWS equivalent and PWRI equivalent diameters were increased by 7.5 mm (p = .013) and 14.0 mm (p < .001) in ruptured cases when compared to non-ruptured controls, respectively. In non-ruptured cases the PWRI equivalent diameters were increased by 13.2 mm (p < .001) in females when compared with males. Biomechanical parameters like PWS and PWRI allow for a highly individualized analysis by integrating factors that influence the risk of AAA rupture like geometry (degree of asymmetry, ILT morphology, etc.) and patient characteristics (gender, family history, blood pressure, etc.). PWRI and the reported annual risk of rupture increase similarly with the diameter. PWRI equivalent diameter expresses the PWRI through the diameter of the average AAA that has the same PWRI, i.e. is at the same biomechanical risk of rupture. Consequently, PWRI equivalent diameter facilitates a straightforward interpretation of biomechanical analysis and connects to diameter-based guidelines for AAA repair indication. PWRI equivalent diameter reflects an additional diagnostic parameter that may provide more accurate clinical data for AAA repair indication. Copyright © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

The Effect of Microstructure and Pre-strain on the Change in Apparent Young's Modulus of a Dual-Phase Steel

NASA Astrophysics Data System (ADS)

Kupke, A.; Hodgson, P. D.; Weiss, M.

2017-07-01

The elastic recovery in dual-phase (DP) steels is not a linear process and changes with plastic deformation. The level of change in the apparent Young's modulus has been reported to depend on material composition and microstructure, but most previous experimental studies were limited to industrial DP steels and led to contradicting results. This work represents a first fundamental study that investigates the separate and combined effect of phase volume fraction and hardness on the change in apparent Young's modulus in DP steel. A common automotive DP steel (DP780) is heat treated to obtain seven different combinations of martensite and ferrite volume fraction and hardness while keeping the chemical composition as well as the shape of the martensite and ferrite phases unchanged. Loading-unloading tests were performed to analyze the chord modulus at various levels of pre-strain. The results suggest that the point of saturation of the chord modulus with pre-strain depends on the morphology of the microstructure, occurring earlier for microstructures consisting of ferrite grains surrounded by martensite laths. It is further revealed that the reduction of the apparent Young's modulus, which is the difference between the material's initial Young's modulus and the chord modulus, increases with martensite hardness if the martensite volume fraction is kept constant. A higher martensite volume fraction initially elevates the reduction of the apparent Young's modulus. After a critical volume fraction of martensite phase of 35%, a decrease in apparent Young's modulus reduction was observed. A comparison of the plastic unloading strain suggests that the mechanisms leading to a reduction in apparent Young's modulus are strongest for the microstructure consisting of 35% martensite volume fraction.

Ruptured Tendons in Anabolic-Androgenic Steroid Users: A Cross-Sectional Cohort Study

PubMed Central

Kanayama, Gen; DeLuca, James; Meehan, William P.; Hudson, James I.; Isaacs, Stephanie; Baggish, Aaron; Weiner, Rory; Micheli, Lyle; Pope, Harrison G.

2016-01-01

Background Accumulating case reports have described tendon rupture in men using anabolic-androgenic steroids (AAS). However no controlled study, to our knowledge, has assessed history of tendon rupture in a large cohort of AAS users and comparison nonusers. Hypothesis We hypothesized that men reporting long-term AAS abuse would report an elevated lifetime incidence of tendon rupture as compared to non-AAS-using bodybuilders. Study Design Cross-sectional cohort study. Methods We obtained medical histories from 142 experienced male bodybuilders age 35–55, recruited in the course of two studies. Of these men, 88 reported at least two years of cumulative lifetime AAS use and 54 reported no history of AAS use. In men reporting a history of tendon rupture, we recorded circumstances of the injury, prodromal symptoms, concomitant drug or alcohol use, and details of current and lifetime AAS use if applicable. We also obtained surgical records for most participants. Results Nineteen (22%) of the AAS users, but only 3 (6%) of the nonusers reported at least one lifetime tendon rupture. The hazard ratio (95% confidence interval) for a first ruptured tendon in AAS users versus nonusers was 9.0 (2.5, 32.3); P <.001. Several men reported two or more independent lifetime tendon ruptures. Interestingly, upper body tendon ruptures occurred exclusively in the AAS group (15 [17%] of the AAS users versus 0 non-users; risk difference 0.17 (0.09, 0.25); P < 0.001 [hazard ratio not estimable]), whereas we found no significant difference between users and nonusers in risk for lower body ruptures (6 [7%] AAS users, 3 [6%] nonusers; hazard ratio 3.1 (0.7, 13.8), P = 0.13). Of 31 individual tendon ruptures that we assessed, only 6 (19%) occurred while weightlifting, with the majority occurring during other sports activities. Eight (26%) ruptures followed prodromal symptoms of nonspecific pain in the region. Virtually all ruptures were treated surgically with complete or near-complete ultimate restoration of function. Conclusions AAS abusers, as compared to otherwise similar bodybuilders, showed a markedly increased risk of tendon ruptures, particularly upper body tendon rupture. Clinical relevance Tendon rupture represents a major adverse consequence of AAS abuse and a substantial public health problem. PMID:26362436

An Analysis of Surgical Treatment for the Spontaneous Rupture of Hepatocellular Carcinoma.

PubMed

Sada, Haruki; Ohira, Masahiro; Kobayashi, Tsuyoshi; Tashiro, Hirotaka; Chayama, Kazuaki; Ohdan, Hideki

2016-01-01

The prognosis of spontaneous rupture of hepatocellular carcinoma (HCC) remains unclear. We investigated the prognosis of patients with ruptured HCC based on the treatments and prognostic factors associated with long-term survival. The prognoses of 64 consecutive patients treated for ruptured HCC from 1986 to 2013 were analyzed according to their methods of treatment. The prognostic factors of 16 surgical patients were identified, and their overall survival (OS) and recurrence rates were compared to 1,157 surgical patients who underwent surgery for non-ruptured HCC. The surgical outcomes were also compared using a propensity score matching method. Surgery was associated with a better OS. Curative resection was the only independent prognostic factor in surgical patients with ruptured HCC (p = 0.040). Although the OS of surgical patients with non-ruptured HCC was found to be significantly better than that of the patients with ruptured HCC, no significant difference in OS was observed after propensity score matching. A curative resection should be the objective of treatment, assuming the suitability of the patient's clinical condition. When the liver function reserve and tumor extension of patients with ruptured and non-ruptured HCC are similar, then their surgical outcomes may not be significantly different. © 2015 S. Karger AG, Basel.

Risk factors affecting chronic rupture of the plantar fascia.

PubMed

Lee, Ho Seong; Choi, Young Rak; Kim, Sang Woo; Lee, Jin Yong; Seo, Jeong Ho; Jeong, Jae Jung

2014-03-01

Prior to 1994, plantar fascia ruptures were considered as an acute injury that occurred primarily in athletes. However, plantar fascia ruptures have recently been reported in the setting of preexisting plantar fasciitis. We analyzed risk factors causing plantar fascia rupture in the presence of preexisting plantar fasciitis. We retrospectively reviewed 286 patients with plantar fasciitis who were referred from private clinics between March 2004 and February 2008. Patients were divided into those with or without a plantar fascia rupture. There were 35 patients in the rupture group and 251 in the nonrupture group. The clinical characteristics and risk factors for plantar fascia rupture were compared between the 2 groups. We compared age, gender, the affected site, visual analog scale pain score, previous treatment regimen, body mass index, degree of ankle dorsiflexion, the use of steroid injections, the extent of activity, calcaneal pitch angle, the presence of a calcaneal spur, and heel alignment between the 2 groups. Of the assessed risk factors, only steroid injection was associated with the occurrence of a plantar fascia rupture. Among the 35 patients with a rupture, 33 had received steroid injections. The odds ratio of steroid injection was 33. Steroid injections for plantar fasciitis should be cautiously administered because of the higher risk for plantar fascia rupture. Level III, retrospective comparative study.

Primary surface rupture associated with the Mw 7.1 16 October 1999 Hector Mine earthquake, San Bernardino County, California

USGS Publications Warehouse

Treiman, J.A.; Kendrick, K.J.; Bryant, W.A.; Rockwell, T.K.; McGill, S.F.

2002-01-01

The Mw 7.1 Hector Mine earthquake occurred within the Mojave Desert portion of the eastern California shear zone and was accompanied by 48 km of dextral surface rupture. Complex northward rupture began on two branches of the Lavic Lake fault in the northern Bullion Mountains and also propagated southward onto the Bullion fault. Lesser amounts of rupture occurred across two right steps to the south. Surface rupture was mapped using postearthquake, 1:10,000-scale aerial photography. Field mapping provided additional detail and more than 400 fault-rupture observations; of these, approximately 300 measurements were used to characterize the slip distribution. En echelon surface rupture predominated in areas of thick alluvium, whereas in the bedrock areas, rupture was more continuous and focused within a narrower zone. Measured dextral offsets were relatively symmetrical about the epicentral region, with a maximum displacement of 5.25 ?? 0.85 m. Vertical slip was a secondary component and was variable, with minor west-side-down displacements predominat.ing in the Bullion Mountains. Field and aerial photographic evidence indicates that most of the faults that ruptured in 1999 had had prior late-Quaternary displacement, although only limited sections of the rupture show evidence for prior Holocene displacement.

Uterine rupture disguised by urinary retention following a second trimester induced abortion: a case report.

PubMed

Jiang, Qiaoying; Yang, Liwei; Ashley, Charles; Medlin, Erin E; Kushner, David M; Zheng, Yanmei

2015-01-22

Uterine rupture classically presents with severe abdominal pain, loss of fetal station, vaginal bleeding, and shock. We present a case of uterine rupture presenting as significant urinary retention that occurred following a second trimester abortion induced with mifepristone and misoprostol. Uterine rupture was discovered unexpectedly on diagnostic laparoscopy. The uterine rupture was contained by dense adhesions between the omentum and bladder with the previous uterine cesarean hysterotomy scar. This case highlights the difficulties in diagnosis of abnormal placentation and an unusual presentation of uterine rupture. This case was managed successfully laparoscopically.

Correlating off-axis tension tests to shear modulus of wood-based panels

Treesearch

Edmond P. Saliklis; Robert H. Falk

2000-01-01

The weakness of existing relationships correlating off-axis modulus of elasticity E q to shear modulus G 12 for wood composite panels is demonstrated through presentation of extensive experimental data. A new relationship is proposed that performs better than existing equations found in the literature. This relationship can be manipulated to calculate the shear modulus...

Method for resonant measurement

DOEpatents

Rhodes, George W.; Migliori, Albert; Dixon, Raymond D.

1996-01-01

A method of measurement of objects to determine object flaws, Poisson's ratio (.sigma.) and shear modulus (.mu.) is shown and described. First, the frequency for expected degenerate responses is determined for one or more input frequencies and then splitting of degenerate resonant modes are observed to identify the presence of flaws in the object. Poisson's ratio and the shear modulus can be determined by identification of resonances dependent only on the shear modulus, and then using that shear modulus to find Poisson's ratio using other modes dependent on both the shear modulus and Poisson's ratio.

Imprint of Rupture Directivity From Ground Motions of the 24 August 2016 Mw6.2 Central Italy Earthquake

NASA Astrophysics Data System (ADS)

Ren, Yefei; Wang, Hongwei; Wen, Ruizhi

2017-12-01

An Mw6.2 earthquake occurred in Central Italy on 24 August 2016. The objective of this study was to reveal the imprint of rupture directivity using the strong motion recordings. The strong motion stations were separated into two groups: southeast (SE) and northwest (NW). The effects of rupture directivity on the peak ground acceleration (PGA), peak ground velocity (PGV), and pseudo spectral acceleration (PSA) were investigated. The observed values of these parameters were compared with predicted values derived from ground motion prediction equations. The results showed that the residuals between the observed and predicted PGAs, PGVs, and PSAs at periods of T < 1 s were correlated significantly with azimuth angle and generally larger in the NW sector, reflecting that the observed PGAs, PGVs, and short-period PSAs in the NW sector were generally larger than observed in the SE sector. These phenomena are accordant with the theoretical law that the rupture directivity causes higher amplitudes in the forward direction compared with the backward direction. Finally, selected source rupture parameters were inverted using PGAs and PGVs. This revealed that the rupture was predominantly unilateral rupture, the major rupture was likely at an azimuth of 360°, and the length of the major rupture was proportional to 70%-100% of the total ruptured fault, confirming that rupture directivity caused the differences in the ground motions observed in the SE and NW sectors.

Interfacial thin films rupture and self-similarity

NASA Astrophysics Data System (ADS)

Ward, Margaret H.

2011-06-01

Two superposed thin layers of fluids are prone to interfacial instabilities due to London-van der Waals forces. Evolution equations for the film thicknesses are derived using lubrication theory. Using the intrinsic scales, for a single layer, results in a system with parametric dependence of four ratios of the two layers: surface tension, Hamaker constant, viscosity, and film thickness. In contrast to the single layer case, the bilayer system has two unstable eigenmodes: squeezing and bending. For some particular parameter regimes, the system exhibits the avoided crossing behavior, where the two eigenmodes are interchanged. Based on numerical analysis, the system evolves into four different rupture states: basal layer rupture, upper layer rupture, double layer rupture, and mixed layer rupture. The ratio of Hamaker constants and the relative film thickness of the two layers control the system dynamics. Remarkably, the line of avoided crossing demarks the transition region of mode mixing and energy transfer, affecting the scaling of the dynamical regime map consequentially. Asymptotic and numerical analyses are used to examine the self-similar ruptures and to extract the power law scalings for both the basal layer rupture and the upper layer rupture. The scaling laws for the basal layer rupture are the same as those of the single layer on top of a substrate. The scaling laws for the upper layer rupture are different: the lateral length scale decreases according to (tr-t)1/3 and the film thickness decreases according to (tr-t)1/6.

Blood flow characteristics in a terminal basilar tip aneurysm prior to its fatal rupture

PubMed Central

Sforza, D.M.; Putman, C.M.; Scrivano, E.; Lylyk, P.; Cebral, J.R.

2010-01-01

Background and Purpose The development and validation of methods to stratify the risk of rupture of cerebral aneurysms is highly desired since current treatment risks can exceed the natural risk of rupture. Because unruptured aneurysms are typically treated before they rupture, it is very difficult to connect the proposed risk indices to the rupture of an individual aneurysm. The purpose of this case study was to analyze the hemodynamic environment of a saccular aneurysm of the terminal morphology sub-type that was imaged just prior to its rupture and to test whether the hemodynamic characteristics would designate this particular aneurysm as at high risk. Methods A patient-specific computational fluid dynamics model was constructed from 3D rotational angiography images acquired just hours before the aneurysm ruptured. A pulsatile flow calculation was performed and hemodynamic characteristics previously connected to rupture were analyzed. Results It was found that the aneurysm had a concentrated inflow stream, small impingement region, complex intra-aneurysmal flow structure, asymmetric flow split from the parent vessel to the aneurysm and daughter branches, and high levels of aneurysmal wall shear stress near the impaction zone. Conclusions The hemodynamics characteristics observed in this aneurysm right before its rupture are consistent with previous studies correlating aneurysm rupture and hemodynamic patterns in saccular and terminal aneurysms. This study supports the notion that hemodynamic information may be used to help stratify the rupture risk of cerebral aneurysms. PMID:20150312

Injuries of the trachea and bronchi

PubMed Central

Bertelsen, S.; Howitz, P.

1972-01-01

Traumatic rupture of the trachea or the bronchi is reported with increasing frequency. Such rupture may follow penetrating wounds, but the common cause is blunt trauma of the throat or thorax. When the proximal trachea is damaged other cervical structures are usually involved. By contrast the distal trachea or bronchi are not infrequently the only thoracic structures damaged. In particular there may be no rib fractures, or obvious fractures may be uncomplicated and insignificant. Thoracic rupture usually occurs in the vicinity of the carina. Central rupture generally presents with emphysema of the mediastinum and neck. Diagnosis can usually be confirmed by tracheobronchoscopy. Rupture of the peripheral bronchi generally presents with pneumothorax and atelectasis. Central rupture should be treated by primary suture. Lobectomy is often necessary when small bronchi are ruptured. PMID:5034596

Induced seismicity provides insight into why earthquake ruptures stop.

PubMed

Galis, Martin; Ampuero, Jean Paul; Mai, P Martin; Cappa, Frédéric

2017-12-01

Injection-induced earthquakes pose a serious seismic hazard but also offer an opportunity to gain insight into earthquake physics. Currently used models relating the maximum magnitude of injection-induced earthquakes to injection parameters do not incorporate rupture physics. We develop theoretical estimates, validated by simulations, of the size of ruptures induced by localized pore-pressure perturbations and propagating on prestressed faults. Our model accounts for ruptures growing beyond the perturbed area and distinguishes self-arrested from runaway ruptures. We develop a theoretical scaling relation between the largest magnitude of self-arrested earthquakes and the injected volume and find it consistent with observed maximum magnitudes of injection-induced earthquakes over a broad range of injected volumes, suggesting that, although runaway ruptures are possible, most injection-induced events so far have been self-arrested ruptures.

Genome-wide association analysis in dogs implicates 99 loci as risk variants for anterior cruciate ligament rupture

PubMed Central

Baker, Lauren A.; Kirkpatrick, Brian; Rosa, Guilherme J. M.; Gianola, Daniel; Valente, Bruno; Sumner, Julia P.; Baltzer, Wendy; Hao, Zhengling; Binversie, Emily E.; Volstad, Nicola; Piazza, Alexander; Sample, Susannah J.

2017-01-01

Anterior cruciate ligament (ACL) rupture is a common condition that can be devastating and life changing, particularly in young adults. A non-contact mechanism is typical. Second ACL ruptures through rupture of the contralateral ACL or rupture of a graft repair is also common. Risk of rupture is increased in females. ACL rupture is also common in dogs. Disease prevalence exceeds 5% in several dog breeds, ~100 fold higher than human beings. We provide insight into the genetic etiology of ACL rupture by genome-wide association study (GWAS) in a high-risk breed using 98 case and 139 control Labrador Retrievers. We identified 129 single nucleotide polymorphisms (SNPs) within 99 risk loci. Associated loci (P<5E-04) explained approximately half of phenotypic variance in the ACL rupture trait. Two of these loci were located in uncharacterized or non-coding regions of the genome. A chromosome 24 locus containing nine genes with diverse functions met genome-wide significance (P = 3.63E-0.6). GWAS pathways were enriched for c-type lectins, a gene set that includes aggrecan, a gene set encoding antimicrobial proteins, and a gene set encoding membrane transport proteins with a variety of physiological functions. Genotypic risk estimated for each dog based on the risk contributed by each GWAS locus showed clear separation of ACL rupture cases and controls. Power analysis of the GWAS data set estimated that ~172 loci explain the genetic contribution to ACL rupture in the Labrador Retriever. Heritability was estimated at 0.48. We conclude ACL rupture is a moderately heritable highly polygenic complex trait. Our results implicate c-type lectin pathways in ACL homeostasis. PMID:28379989

Glass rupture disk

DOEpatents

Glass, S. Jill; Nicolaysen, Scott D.; Beauchamp, Edwin K.

2002-01-01

A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

Physical property measurements of doped cesium iodide crystals

NASA Technical Reports Server (NTRS)

Synder, R. S.; Clotfelter, W. N.

1974-01-01

Mechanical and thermal property values are reported for crystalline cesium iodide doped with sodium and thallium. Young's modulus, bulk modulus, shear modulus, and Poisson's ratio were obtained from ultrasonic measurements. Young's modulus and the samples' elastic and plastic behavior were also measured under tension and compression. Thermal expansion and thermal conductivity were the temperature dependent measurements that were made.

Kinetics of the Multistep Rupture of Fibrin ‘A-a’ Polymerization Interactions Measured Using Atomic Force Microscopy

PubMed Central

Averett, Laurel E.; Schoenfisch, Mark H.; Akhremitchev, Boris B.; Gorkun, Oleg V.

2009-01-01

Abstract Fibrin, the structural scaffold of blood clots, spontaneously polymerizes through the formation of ‘A-a’ knob-hole bonds. When subjected to external force, the dissociation of this bond is accompanied by two to four abrupt changes in molecular dimension observable as rupture events in a force curve. Herein, the configuration, molecular extension, and kinetic parameters of each rupture event are examined. The increases in contour length indicate that the D region of fibrinogen can lengthen by ∼50% of the length of a fibrin monomer before rupture of the ‘A-a’ interaction. The dependence of the dissociation rate on applied force was obtained using probability distributions of rupture forces collected at different pull-off velocities. These distributions were fit using a model in which the effects of the shape of the binding potential are used to quantify the kinetic parameters of forced dissociation. We found that the weak initial rupture (i.e., event 1) was not well approximated by these models. The ruptured bonds comprising the strongest ruptures, events 2 and 3, had kinetic parameters similar to those commonly found for the mechanical unfolding of globular proteins. The bonds ruptured in event 4 were well described by these analyses, but were more loosely bound than the bonds in events 2 and 3. We propose that the first event represents the rupture of an unknown interaction parallel to the ‘A-a’ bond, events 2 and 3 represent unfolding of structures in the D region of fibrinogen, and event 4 is the rupture of the ‘A-a’ knob-hole bond weakened by prior structural unfolding. Comparison of the activation energy obtained via force spectroscopy measurements with the thermodynamic free energy of ‘A-a’ bond dissociation indicates that the ‘A-a’ bond may be more resistant to rupture by applied force than to rupture by thermal dissociation. PMID:19917237

Spontaneous rupture of ovarian cystadenocarcinoma: pre- and post-rupture computed tomography evaluation*

PubMed Central

Salvadori, Priscila Silveira; Bomfim, Lucas Novais; von Atzingen, Augusto Castelli; D’Ippolito, Giuseppe

2015-01-01

Epithelial ovarian tumors are the most common malignant ovarian neoplasms and, in most cases, eventual rupture of such tumors is associated with a surgical procedure. The authors report the case of a 54-year-old woman who presented with spontaneous rupture of ovarian cystadenocarcinoma documented by computed tomography, both before and after the event. In such cases, a post-rupture staging tends to be less favorable, compromising the prognosis. PMID:26543286

Effects of Reorientation of Graphene Platelets (GPLs) on Young’s Modulus of Polymer Composites under Bi-Axial Stretching

PubMed Central

Yang, Jie

2018-01-01

Effects of bi-axial stretching induced reorientation of graphene platelets (GPLs) on the Young’s modulus of GPL/polymer composites is studied by Mori-Tanaka micromechanics model. The dispersion state of the GPLs in polymer matrix is captured by an orientation distribution function (ODF), in which two Euler angles are used to identify the orientation of the GPLs. Compared to uni-axial stretching, the increase of the stretching strain in the second direction enhances the re-alignment of GPL fillers in this direction while it deteriorates the re-alignment of the fillers in the other two directions. Comprehensive parametric study on the effects of the out-of-plane Young’s modulus, stretching strain, strain ratio, Poisson’s ratio and weight fraction and GPL dimension on the effective Young’s moduli of the composites in the three directions are conducted. It is found that the out-of-plane Young’s modulus has limited effects on the overall Young’s modulus of the composites. The second stretching enhances the Young’s modulus in this direction while it decreases the Young’s modulus in the other two directions. The results demonstrate the increase of Poisson’s ratio is favorable in increasing the Young’s modulus of the composites. GPLs with larger diameter-to-thickness ratio have better reinforcing effect on the Young’s modulus of GPL/polymer nanocomposites. PMID:29316669

Definitive diagnosis of breast implant rupture using magnetic resonance imaging.

PubMed

Ahn, C Y; Shaw, W W; Narayanan, K; Gorczyca, D P; Sinha, S; Debruhl, N D; Bassett, L W

1993-09-01

Breast implant rupture is an important complication of augmented and reconstructed breasts. Although several techniques such as mammography, xeromammography, ultrasound, thermography, and computed tomographic (CT) scanning have been proven to be useful to detect implant rupture, they have several disadvantages and lack specificity. In the current study, we have established magnetic resonance imaging (MRI) as a definitive, reliable, and reproducible technique to diagnose both intracapsular and extracapsular ruptures. The study was conducted in 100 symptomatic patients. Our imaging parameters were able to identify ruptures in implants with silicone shells. All the ruptures showed the presence of wavy lines, free-floating silicone shell within the gel ("free-floating loose-thread sign" or "linguine sign"). We had a 3.75 percent incidence of false-positive and false-negative results. The sensitivity for detection of silicone implant rupture was 76 percent, with a specificity of 97 percent. In addition, we also were able to identify the artifacts that may interfere with the definitive diagnosis of implant rupture.

Ultrahigh Elastic Strain Energy Storage in Metal-Oxide-Infiltrated Patterned Hybrid Polymer Nanocomposites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dusoe, Keith J.; Ye, Xinyi; Kisslinger, Kim

Modulus of resilience, the measure of a material’s capacity to store and release elastic strain energy, is critical for realizing advanced mechanical actuation technologies in micro/nanoelectromechanical systems. In general, engineering the modulus of resilience is difficult because it requires asymmetrically increasing yield strength and Young’s modulus against their mutual scaling behavior. This task becomes further challenging if it needs to be carried out at the nanometer scale. Here, we demonstrate organic–inorganic hybrid composite nanopillars with one of the highest modulus of resilience per density by utilizing vapor-phase aluminum oxide infiltration in lithographically patterned negative photoresist SU-8. In situ nanomechanical measurementsmore » reveal a metal-like high yield strength (~500 MPa) with an unusually low, foam-like Young’s modulus (~7 GPa), a unique pairing that yields ultrahigh modulus of resilience, reaching up to ~24 MJ/m 3 as well as exceptional modulus of resilience per density of ~13.4 kJ/kg, surpassing those of most engineering materials. The hybrid polymer nanocomposite features lightweight, ultrahigh tunable modulus of resilience and versatile nanoscale lithographic patternability with potential for application as nanomechanical components which require ultrahigh mechanical resilience and strength.« less

Ultrahigh Elastic Strain Energy Storage in Metal-Oxide-Infiltrated Patterned Hybrid Polymer Nanocomposites

DOE PAGES

Dusoe, Keith J.; Ye, Xinyi; Kisslinger, Kim; ...

2017-10-19

Modulus of resilience, the measure of a material’s capacity to store and release elastic strain energy, is critical for realizing advanced mechanical actuation technologies in micro/nanoelectromechanical systems. In general, engineering the modulus of resilience is difficult because it requires asymmetrically increasing yield strength and Young’s modulus against their mutual scaling behavior. This task becomes further challenging if it needs to be carried out at the nanometer scale. Here, we demonstrate organic–inorganic hybrid composite nanopillars with one of the highest modulus of resilience per density by utilizing vapor-phase aluminum oxide infiltration in lithographically patterned negative photoresist SU-8. In situ nanomechanical measurementsmore » reveal a metal-like high yield strength (~500 MPa) with an unusually low, foam-like Young’s modulus (~7 GPa), a unique pairing that yields ultrahigh modulus of resilience, reaching up to ~24 MJ/m 3 as well as exceptional modulus of resilience per density of ~13.4 kJ/kg, surpassing those of most engineering materials. The hybrid polymer nanocomposite features lightweight, ultrahigh tunable modulus of resilience and versatile nanoscale lithographic patternability with potential for application as nanomechanical components which require ultrahigh mechanical resilience and strength.« less

A Three Year Clinicopathological Study of Cases of Rupture Uterus

PubMed Central

Rathod, Setu; Swain, Sujata

2015-01-01

Introduction Rupture uterus is a life threatening obstetric complication with serious maternal and fetal side-effects. We report a 3 year (2010-2013) retrospective clinical study of pregnancy with rupture uterus cases attending a tertiary care hospital. Aim The aim of the study was to evaluate the incidence of rupture uterus, incidence as per age, parity, clinical presentations, risk factors, complications and management. Materials and Methods Retrospective data of 74 cases of rupture uterus in SCB Medical college, Cuttack was collected from case records of 26,547 deliveries during a 3 year span (2010-2013). Parameters like cause of rupture, type, site of rupture and outcome were recorded. The collected data was analysed by SPSS software v19. Results Out of 26,547 deliveries during the three year period, there were 74 cases of rupture uterus with an incidence of rupture 1 in 359 (0.28%). The mean age of rupture uterus was 27.4 years. 95.8% were multigravida and majority were referred cases from low socioeconomic status. Only 40.5% had the required minimum of four antenatal visits as recommended by WHO (World Health Organisation). A total of 48.6% of cases with rupture uterus had history of previous Caesarean section. Prolonged labour was present in 75.6% of the cases. Only 12.2% of the cases had history of oxytocin use whereas 9.5% had undergone an operative vaginal delivery. Obstructed labour was the cause in 24.3% of cases, 85.1% had complete rupture. Majority had a rupture in the anterior wall (69%) and 81.1% had rupture in lower segment of uterus. Only 17.6% had broad ligament haematoma, 10.8% colporrhexis and 6.8% had associated bladder injury. Repair was possible in only 39.2% of cases, whereas majority landed up in hysterectomy. Internal iliac ligation was done in 2.7% of cases. Perinatal mortality was 90.5% whereas maternal death was seen in 13.5% cases. One patient developed VVF (vesicovaginal fistula). Duration of hospital stay was upto 14 days in 81.1% cases. Conclusion Education and proper care especially of high risk patients like previous caesarean by competent personnal, proper use of oxytocin and early referral may help to reduce the incidence of “rupture uterus”. PMID:26673858

Secular pattern of aneurismal rupture with the lunar cycle and season.

PubMed

Banfield, Jillian C; Abdolell, Mohamed; Shankar, Jai S

2017-02-01

Background The lunar cycle and seasons may be associated with rates of rupture of intracranial aneurysms, but the literature is mixed. Studies of the association between the lunar cycle and rates of aneurysm rupture used the eight qualitative moon phases. The purpose of this study was to assess any association of aneurysm rupture with the lunar cycle and with the season. Materials and methods We retrospectively reviewed all cases of subarachnoid haemorrhage secondary to ruptured intracranial aneurysm treated with endovascular coiling in our institution over a 10-year period. We included only cases with a known rupture date. We used the degree of illumination of the moon to quantitatively code the lunar cycle. Results A total of 212 cases were included in our analyses. The odds of aneurysm rupture were significantly greater ( p < 0.001) when the moon was least (new moon) and most (full moon) illuminated, as compared to the middle of the lunar cycle. The odds of rupture tended to be higher ( p = 0.059) in the summer, compared to autumn. Conclusions The odds of aneurysm rupture were greater when the moon was least illuminated (new moon) and most illuminated (full moon), compared to the middle of the lunar cycle.

[Spontaneous splenic rupture due to infectious acute mononucleosis: case report].

PubMed

Greco, L; De Gennaro, E; Degara, A; Papa, U

2003-01-01

Infectious mononucleosis is an acute, viral, illness associated with a high incidence of splenomegaly. Spontaneous splenic rupture is a rare but life-threatening complication of infectious mononucleosis. The authors report the case of a 19-year-old patient with an infectious mononucleosis causing a spontaneous splenic rupture. When rupture occurs the mortality has been significant. The spleen may be vulnerable for the histopathologic changes that occur as a result of this illness. Two thirds of patients with infectious mononucleosis develop an enlarged spleen, but in only 0.5% of all patients will it rupture. Abdominal pain and tachycardia are unusual in uncomplicated infectious mononucleosis and should alert a doctor to the possibility of spontaneous splenic rupture. The diagnosis of splenic rupture may be confirmed in a variety of ways. In this patient ultrasound and Rutkow's criteria may aid in establishing the diagnosis. In patients with infectious mononucleosis suspected of having rupture of the spleen, a rapid but thorough assessment and prompt implementation of appropriate management should minimize the associated morbidity and mortality. On the basis of review of the medical literature and of our own experience, we advocate emergent splenectomy for spontaneous splenic rupture in patients with infectious mononucleosis.

Influence of fault steps on rupture termination of strike-slip earthquake faults

NASA Astrophysics Data System (ADS)

Li, Zhengfang; Zhou, Bengang

2018-03-01

A statistical analysis was completed on the rupture data of 29 historical strike-slip earthquakes across the world. The purpose of this study is to examine the effects of fault steps on the rupture termination of these events. The results show good correlations between the type and length of steps with the seismic rupture and a poor correlation between the step number and seismic rupture. For different magnitude intervals, the smallest widths of the fault steps (Lt) that can terminate the rupture propagation are variable: Lt = 3 km for Ms 6.5 6.9, Lt = 4 km for Ms 7.0 7.5, Lt = 6 km for Ms 7.5 8.0, and Lt = 8 km for Ms 8.0 8.5. The dilational fault step is easier to rupture through than the compression fault step. The smallest widths of the fault step for the rupture arrest can be used as an indicator to judge the scale of the rupture termination of seismic faults. This is helpful for research on fault segmentation, as well as estimating the magnitude of potential earthquakes, and is thus of significance for the assessment of seismic risks.

Non-toxic invert analog glass compositions of high modulus

NASA Technical Reports Server (NTRS)

Bacon, J. F. (Inventor)

1974-01-01

Glass compositions having a Young's modulus of at least 15 million psi are described. They and a specific modulus of at least 110 million inches consist essentially of, in mols, 15 to 40% SiO2, 6 to 15% Li2O, 24 to 45% of at least two bivalent oxides selected from the group consisting of Ca, NzO, MgO and CuO; 13 to 39% of at least two trivalent oxides selected from the group consisting of Al2O3, Fe2O3, B2O3, La2O3, and Y2O3 and up to 15% of one or more tetravelent oxides selected from the group consisting of ZrO2, TiO2 and CeO2. The high modulus, low density glass compositions contain no toxic elements. The composition, glass density, Young's modulus, and specific modulus for 28 representative glasses are presented. The fiber modulus of five glasses are given.

Precursory, Nucleation and Propagation of Ruptures Along Heterogeneously Loaded, Circular Experimental Faults

NASA Astrophysics Data System (ADS)

Reches, Z.; Zu, X.; Jeffers, J.

2017-12-01

We explored the evolution of dynamic rupture along a circular experimental fault composed of clear acrylic blocks. The ring-shaped fault surface has inner and outer diameters of 7.72 and 10.16 cm, respectively. An array of ten rossette strain-gauges is attached to the outer rim of one block that provide the 2D strain tensor in a plane normal to the fault. The 30 components of the gauges are monitored at 10^6 samples/second. One 3D miniature accelerometer is attached to the fault block. The initial asperities of the fault surface generated a non-uniform strain (=stress) distribution that was recorded, and indicated local deviations of ±30% from the mean stress. The mean normal stress was up to 3.5 MPa, the remotely applied velocity was up to .002 m/s, and the slip velocities during rupture were not measured. The rupture characteristics, namely propagation velocity and rupture front strain-field, were determined from strain-gauge outputs. The analysis of tens of stick-slip events revealed the following preliminary results: (1) The ruptures consistently nucleated at sites of high local strains (=stresses) that were formed by the pre-shear, normal stress loading. (2) The pre-rupture nucleation process was recognized a by temporal (< 0.1 s), local (<20 mm) reduction of the shear strain. (3) Commonly, the initiation of nucleation was associated with micro acoustic emissions, whereas the initiation of rupture was associated with intense acoustic activity. (4) Nucleation could occur quasi-simultaneously at two, highly stressed sites. (5) From the nucleation site, the ruptures propagated in two directions along the ring-shaped fault, and the collision between the two fronts led to rupture `shut-off'. (5) The strain-field of rupture fronts was well-recognized for ruptures propagating faster than 50 m/s, and the fastest fronts propagated at 1000 m/s. (7) It appears that the rupture front strain-field close to the nucleation site differs from the front strain-field far from nucleation site. (8) Post-shear examination of the fault surfaces revealed evidence of brittle wear of the acrylic including gouge formation, ploughing, and powder smearing. (9) Work in progress includes attempts to achieve faster dynamic ruptures, and the utilization of the existing monitoring system to rupture granite faults.

Comparing slow and fast rupture in laboratory experiments

NASA Astrophysics Data System (ADS)

Aben, F. M.; Brantut, N.; David, E.; Mitchell, T. M.

2017-12-01

During the brittle failure of rock, elastically stored energy is converted into a localized fracture plane and surrounding fracture damage, seismic radiation, and thermal energy. However, the partitioning of energy might vary with the rate of elastic energy release during failure. Here, we present the results of controlled (slow) and dynamic (fast) rupture experiments on dry Lanhélin granite and Westerly granite samples, performed under triaxial stress conditions at confining pressures of 50 and 100 MPa. During the tests, we measured sample shortening, axial load and local strains (with 2 pairs of strain gauges glued directly onto the sample). In addition, acoustic emissions (AEs) and changes in seismic velocities were monitored. The AE rate was used as an indicator to manually control the axial load on the sample to stabilize rupture in the quasi-static failure experiments. For the dynamic rupture experiments a constant strain rate of 10-5 s-1 was applied until sample failure. A third experiment, labeled semi-controlled rupture, involved controlled rupture up to a point where the rupture became unstable and the remaining elastic energy was released dynamically. All experiments were concluded after a macroscopic fracture had developed across the whole sample and frictional sliding commenced. Post-mortem samples were epoxied, cut and polished to reveal the macroscopic fracture and the surrounding damage zone. The samples failed with average rupture velocities varying from 5x10-6 m/s up to >> 0.1 m/s. The analyses of AE locations on the slow ruptures reveal that within Westerly granite samples - with a smaller grain size - fracture planes are disbanded in favor of other planes when a geometrical irregularity is encountered. For the coarser grained Lanhélin granite a single fracture plane is always formed, although irregularities are recognized as well. The semi-controlled experiments show that for both rock types the rupture can become unstable in response to these irregularities. In Westerly granite, slow rupture experiments tend to produce complex fracture patterns while during the dynamic rupture experiments secondary rupture planes are not formed. These findings show that grain or flaw size, flaw distribution, and rupture speed strongly influence fracture localization and propagation.

Systematic Observations of the Slip-pulse Properties of Large Earthquake Ruptures

NASA Astrophysics Data System (ADS)

Melgar, D.; Hayes, G. P.

2017-12-01

In earthquake dynamics there are two end member models of rupture: propagating cracks and self-healing pulses. These arise due to different properties of ruptures and have implications for seismic hazard; rupture mode controls near-field strong ground motions. Past studies favor the pulse-like mode of rupture, however, due to a variety of limitations, it has proven difficult to systematically establish their kinematic properties. Here we synthesize observations from a database of >150 rupture models of earthquakes spanning M7-M9 processed in a uniform manner and show the magnitude scaling properties (rise time, pulse width, and peak slip rate) of these slip pulses indicates self-similarity. Self similarity suggests a weak form of rupture determinism, where early on in the source process broader, higher amplitude slip pulses will distinguish between events of icnreasing magnitude. Indeed, we find by analyzing the moment rate functions that large and very large events are statistically distinguishable relatively early (at 15 seconds) in the rupture process. This suggests that with dense regional geophysical networks strong ground motions from a large rupture can be identified before their onset across the source region.

Rupture directivity of microseismic events recorded during hydraulic fracture stimulations.

NASA Astrophysics Data System (ADS)

Urbancic, T.; Smith-Boughner, L.; Baig, A.; Viegas, G.

2016-12-01

We model the dynamics of a complex rupture sequence with four sub-events. These events were recorded during hydraulic fracture stimulations in a gas-bearing shale formation. With force-balance accelerometers, 4.5Hz and 15Hz instruments recording the failure history, we study the directivity of the entire rupture sequence and each sub-event. Two models are considered: unilateral and bi-lateral failures of penny shaped cracks. From the seismic moment tensors of these sub-events, we consider different potential failure planes and rupture directions. Using numerical wave-propagation codes, we generate synthetic rupture sequences with both unilateral and bi-lateral ruptures. These are compared to the four sub-events to determine the directionality of the observed failures and the sensitivity of our recording bandwidth and geometry to distinguishing between different rupture processes. The frequency of unilateral and bilateral rupture processes throughout the fracture stimulation is estimated by comparing the directivity characteristics of the modeled sub-events to other high-quality microseismic events recorded during the same stimulation program. Understanding the failure processes of these microseismic events can provide great insight into the changes in the rock mass responsible for these complex rupture processes.

A fractional model with parallel fractional Maxwell elements for amorphous thermoplastics

NASA Astrophysics Data System (ADS)

Lei, Dong; Liang, Yingjie; Xiao, Rui

2018-01-01

We develop a fractional model to describe the thermomechanical behavior of amorphous thermoplastics. The fractional model is composed of two parallel fractional Maxwell elements. The first fractional Maxwell model is used to describe the glass transition, while the second component is aimed at describing the viscous flow. We further derive the analytical solutions for the stress relaxation modulus and complex modulus through Laplace transform. We then demonstrate the model is able to describe the master curves of the stress relaxation modulus, storage modulus and loss modulus, which all show two distinct transition regions. The obtained parameters show that the modulus of the two fractional Maxwell elements differs in 2-3 orders of magnitude, while the relaxation time differs in 7-9 orders of magnitude. Finally, we apply the model to describe the stress response of constant strain rate tests. The model, together with the parameters obtained from fitting the master curve of stress relaxation modulus, can accurately predict the temperature and strain rate dependent stress response.

Traumatic graft rupture after primary and revision anterior cruciate ligament reconstruction: retrospective analysis of incidence and risk factors in 2915 cases.

PubMed

Schlumberger, Michael; Schuster, Philipp; Schulz, Martin; Immendörfer, Micha; Mayer, Philipp; Bartholomä, Jochen; Richter, Jörg

2017-05-01

To determine incidence and risk factors for traumatic graft rupture following primary and revision anterior cruciate ligament (ACL) reconstruction. All cases of isolated ACL reconstructions (primary or revision) performed at our institution between January 2007 and December 2010 were included. From this group of 2467 primary reconstructions (32.4 ± 12.2 years) and 448 revision reconstructions (33.0 ± 10.4 years), we identified all patients who underwent revision ACL reconstruction following traumatic graft rupture in further course and all patients who underwent contralateral primary ACL reconstruction until January 2014. Age, gender, time from index procedure and graft diameter (for hamstring autografts) were analysed in terms of being a potential risk factor for graft rupture. Within a follow-up period of 5.0 ± 1.1 years (3.0-7.0), a total of 82 traumatic graft ruptures were identified, resulting in an incidence of 2.8 %. Seventy-three cases were seen following primary reconstructions (3.0 %), and nine cases following revision reconstructions (2.0 %), respectively (n.s.). Age younger than 25 years was identified as a risk factor for both groups (p = 0.001 and p = 0.008; odds ratio 6.0 and 6.4, respectively). In primary reconstruction, male patients had a higher risk of graft rupture compared with females (3.7 vs. 1.6 %; p = 0.005), and the first year after index procedure was associated with a higher risk of graft rupture compared with the following (p < 0.001). Graft diameter did not influence the risk of graft rupture. Incidence of contralateral ACL rupture was 3.1 %, which was not different to the incidence of graft rupture ipsilaterally (n.s.). No statistically significant differences were seen between graft rupture incidence of primary and revision ACL reconstructions. Young age (<25 years) and short time to the index procedure (especially within the first year) were confirmed as risk factors for graft rupture in both groups. Male gender was a risk factor for primary reconstructions. Graft diameter had no influence on graft rupture rates. No difference in incidence of graft rupture compared to ACL rupture on the contralateral side was apparent. Retrospective case series, Level IV.

Time and temperature dependent modulus of pyrrone and polyimide moldings

NASA Technical Reports Server (NTRS)

Lander, L. L.

1972-01-01

A method is presented by which the modulus obtained from a stress relaxation test can be used to estimate the modulus which would be obtained from a sonic vibration test. The method was applied to stress relaxation, sonic vibration, and high speed stress-strain data which was obtained on a flexible epoxy. The modulus as measured by the three test methods was identical for identical test times, and a change of test temperature was equivalent to a shift in the logarithmic time scale. An estimate was then made of the dynamic modulus of moldings of two Pyrrones and two polyimides, using stress relaxation data and the method of analysis which was developed for the epoxy. Over the common temperature range (350 to 500 K) in which data from both types of tests were available, the estimated dynamic modulus value differed by only a few percent from the measured value. As a result, it is concluded that, over the 500 to 700 K temperature range, the estimated dynamic modulus values are accurate.

Assessment of Characteristic Function Modulus of Vibroacoustic Signal Given a Limit State Parameter of Diagnosed Equipment

NASA Astrophysics Data System (ADS)

Kostyukov, V. N.; Naumenko, A. P.; Kudryavtseva, I. S.

2018-01-01

Improvement of distinguishing criteria, determining defects of machinery and mechanisms, by vibroacoustic signals is a recent problem for technical diagnostics. The work objective is assessment of instantaneous values by methods of statistical decision making theory and risk of regulatory values of characteristic function modulus. The modulus of the characteristic function is determined given a fixed parameter of the characteristic function. It is possible to determine the limits of the modulus, which correspond to different machine’s condition. The data of the modulus values are used as diagnostic features in the vibration diagnostics and monitoring systems. Using such static decision-making methods as: minimum number of wrong decisions, maximum likelihood, minimax, Neumann-Pearson characteristic function modulus limits are determined, separating conditions of a diagnosed object.

Multi-Fault Rupture Scenarios in the Brawley Seismic Zone

NASA Astrophysics Data System (ADS)

Kyriakopoulos, C.; Oglesby, D. D.; Rockwell, T. K.; Meltzner, A. J.; Barall, M.

2017-12-01

Dynamic rupture complexity is strongly affected by both the geometric configuration of a network of faults and pre-stress conditions. Between those two, the geometric configuration is more likely to be anticipated prior to an event. An important factor in the unpredictability of the final rupture pattern of a group of faults is the time-dependent interaction between them. Dynamic rupture models provide a means to investigate this otherwise inscrutable processes. The Brawley Seismic Zone in Southern California is an area in which this approach might be important for inferring potential earthquake sizes and rupture patterns. Dynamic modeling can illuminate how the main faults in this area, the Southern San Andreas (SSAF) and Imperial faults, might interact with the intersecting cross faults, and how the cross faults may modulate rupture on the main faults. We perform 3D finite element modeling of potential earthquakes in this zone assuming an extended array of faults (Figure). Our results include a wide range of ruptures and fault behaviors depending on assumptions about nucleation location, geometric setup, pre-stress conditions, and locking depth. For example, in the majority of our models the cross faults do not strongly participate in the rupture process, giving the impression that they are not typically an aid or an obstacle to the rupture propagation. However, in some cases, particularly when rupture proceeds slowly on the main faults, the cross faults indeed can participate with significant slip, and can even cause rupture termination on one of the main faults. Furthermore, in a complex network of faults we should not preclude the possibility of a large event nucleating on a smaller fault (e.g. a cross fault) and eventually promoting rupture on the main structure. Recent examples include the 2010 Mw 7.1 Darfield (New Zealand) and Mw 7.2 El Mayor-Cucapah (Mexico) earthquakes, where rupture started on a smaller adjacent segment and later cascaded into a larger event. For that reason, we are investigating scenarios of a moderate rupture on a cross fault, and determining conditions under which the rupture will propagate onto the adjacent SSAF. Our investigation will provide fundamental insights that may help us interpret faulting behaviors in other areas, such as the complex Mw 7.8 2016 Kaikoura (New Zealand) earthquake.

Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms

PubMed Central

Karmonik, Christof; Fang, Yibin; Xu, Jinyu; Yu, Ying; Cao, Wei; Liu, Jianmin; Huang, Qinghai

2016-01-01

Background and Purpose The conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA) aneurysms. Materials and Methods In 129 PCoA aneurysms (85 ruptured, 44 unruptured), clinical, morphological and hemodynamic characteristics were compared between the ruptured and unruptured cases. Multivariate logistic regression analysis was performed to determine the discriminators for rupture status of PCoA aneurysms. Results While univariate analyses showed that the size of aneurysm dome, aspect ratio (AR), size ratio (SR), dome-to-neck ratio (DN), inflow angle (IA), normalized wall shear stress (NWSS) and percentage of low wall shear stress area (LSA) were significantly associated with PCoA aneurysm rupture status. With multivariate analyses, significance was only retained for higher IA (OR = 1.539, p < 0.001) and LSA (OR = 1.393, p = 0.041). Conclusions Hemodynamics and morphology were related to rupture status of intracranial aneurysms. Higher IA and LSA were identified as discriminators for rupture status of PCoA aneurysms. PMID:26910518

Morphological and Hemodynamic Discriminators for Rupture Status in Posterior Communicating Artery Aneurysms.

PubMed

Lv, Nan; Wang, Chi; Karmonik, Christof; Fang, Yibin; Xu, Jinyu; Yu, Ying; Cao, Wei; Liu, Jianmin; Huang, Qinghai

2016-01-01

The conflicting findings of previous morphological and hemodynamic studies on intracranial aneurysm rupture may be caused by the relatively small sample sizes and the variation in location of the patient-specific aneurysm models. We aimed to determine the discriminators for aneurysm rupture status by focusing on only posterior communicating artery (PCoA) aneurysms. In 129 PCoA aneurysms (85 ruptured, 44 unruptured), clinical, morphological and hemodynamic characteristics were compared between the ruptured and unruptured cases. Multivariate logistic regression analysis was performed to determine the discriminators for rupture status of PCoA aneurysms. While univariate analyses showed that the size of aneurysm dome, aspect ratio (AR), size ratio (SR), dome-to-neck ratio (DN), inflow angle (IA), normalized wall shear stress (NWSS) and percentage of low wall shear stress area (LSA) were significantly associated with PCoA aneurysm rupture status. With multivariate analyses, significance was only retained for higher IA (OR = 1.539, p < 0.001) and LSA (OR = 1.393, p = 0.041). Hemodynamics and morphology were related to rupture status of intracranial aneurysms. Higher IA and LSA were identified as discriminators for rupture status of PCoA aneurysms.

Measurement of Young's modulus in the in vivo human vocal folds.

PubMed

Tran, Q T; Berke, G S; Gerratt, B R; Kreiman, J

1993-08-01

Currently, surgeons have no objective means to evaluate and optimize results of phonosurgery intraoperatively. Instead, they usually judge the vocal folds subjectively by visual inspection or by listening to the voice. This paper describes a new device that measures Young's (elastic) modulus values for the human vocal fold intraoperatively. Physiologically, the modulus of the vocal fold may be important in determining the nature of vocal fold vibration in normal and pathologic states. This study also reports the effect of recurrent laryngeal nerve stimulation on Young's modulus of the human vocal folds, measured by means of transcutaneous nerve stimulation techniques. Young's modulus increased with increases in current stimulation to the recurrent laryngeal nerve. Ultimately, Young's modulus values may assist surgeons in optimizing the results of various phonosurgeries.

Fractal avalanche ruptures in biological membranes

NASA Astrophysics Data System (ADS)

Gözen, Irep; Dommersnes, Paul; Czolkos, Ilja; Jesorka, Aldo; Lobovkina, Tatsiana; Orwar, Owe

2010-11-01

Bilayer membranes envelope cells as well as organelles, and constitute the most ubiquitous biological material found in all branches of the phylogenetic tree. Cell membrane rupture is an important biological process, and substantial rupture rates are found in skeletal and cardiac muscle cells under a mechanical load. Rupture can also be induced by processes such as cell death, and active cell membrane repair mechanisms are essential to preserve cell integrity. Pore formation in cell membranes is also at the heart of many biomedical applications such as in drug, gene and short interfering RNA delivery. Membrane rupture dynamics has been studied in bilayer vesicles under tensile stress, which consistently produce circular pores. We observed very different rupture mechanics in bilayer membranes spreading on solid supports: in one instance fingering instabilities were seen resulting in floral-like pores and in another, the rupture proceeded in a series of rapid avalanches causing fractal membrane fragmentation. The intermittent character of rupture evolution and the broad distribution in avalanche sizes is consistent with crackling-noise dynamics. Such noisy dynamics appear in fracture of solid disordered materials, in dislocation avalanches in plastic deformations and domain wall magnetization avalanches. We also observed similar fractal rupture mechanics in spreading cell membranes.

Simultaneous bilateral Achilles tendon ruptures associated with statin medication despite regular rock climbing exercise.

PubMed

Carmont, Michael R; Highland, Adrian M; Blundell, Christopher M; Davies, Mark B

2009-11-01

Ruptures of the Achilles tendon are common however simultaneous ruptures occur less frequently. Eccentric loading exercise programmes have been used to successfully treat Achilles tendinopathy. We report a case of simultaneous bilateral Achilles tendon rupture in a patient predisposed to rupture due to longstanding raised serum lipoprotein and recently introduced therapeutic statin medication. The patient was also a keen rock climber and had regularly undertaken loading exercise. This case illustrates that the therapeutic effect of mixed loading exercises for the Achilles tendon may not be adequate to overcome the predisposition to rupture caused by hyperlipidaemia and statin medication.

Preterm premature rupture of membranes at 22-25 weeks' gestation: perinatal and 2-year outcomes within a national population-based study (EPIPAGE-2).

PubMed

Lorthe, Elsa; Torchin, Héloïse; Delorme, Pierre; Ancel, Pierre-Yves; Marchand-Martin, Laetitia; Foix-L'helias, Laurence; Benhammou, Valérie; Gire, Catherine; D'Ercole, Claude; Winer, Norbert; Sentilhes, Loïc; Subtil, Damien; Goffinet, François; Kayem, Gilles

2018-05-28

Most clinical guidelines state that with early preterm premature rupture of membranes, obstetric and pediatric teams must share a realistic and individualized appraisal of neonatal outcomes with parents and consider their wishes for all decisions. However, we currently lack reliable and relevant data, according to gestational age at rupture of membranes, to adequately counsel parents during pregnancy and to reflect on our policies of care at these extreme gestational ages. To describe both perinatal and 2-year outcomes of preterm infants born after preterm premature rupture of membranes at 22-25 weeks' gestation. EPIPAGE-2 is a French national prospective population-based cohort of preterm infants born in 546 maternity units in 2011. Inclusion criteria in this analysis were women diagnosed with preterm premature rupture of membranes at 22-25 weeks' gestation and singleton or twin gestations with fetus(es) alive at rupture of membranes. Latency duration, antenatal management, and outcomes (survival at discharge, survival at discharge without severe morbidity, and survival at 2 years' corrected age without cerebral palsy) were described and compared by gestational age at preterm premature rupture of membranes. Among the 1435 women with a diagnosis of preterm premature rupture of membranes, 379 were at 22-25 weeks' gestation, with 427 fetuses (331 singletons and 96 twins). Median GA at preterm premature rupture of membranes and at birth were 24 (interquartile range 23-25) and 25 (24-27) weeks, respectively. For each gestational age at preterm premature rupture of membranes, nearly half of the fetuses were born within the week after the rupture of membranes. Among the 427 fetuses, 51.7% were survivors at discharge (14.1%, 39.5%, 66.8% and 75.8% with preterm premature rupture of membranes at 22, 23, 24 and 25 weeks, respectively), 38.8% were survivors at discharge without severe morbidity and 46.4% were survivors at 2 years without cerebral palsy, with wide variations by gestational age at preterm premature rupture of membranes. Survival at 2 years without cerebral palsy was low with preterm premature rupture of membranes at 22 and 23 weeks but reached approximately 60% and 70% with preterm premature rupture of membranes at 24 and 25 weeks. Preterm premature rupture of membranes at 22-25 weeks is associated with high incidence of mortality and morbidity, with wide variations by gestational age at preterm premature rupture of membranes. However, a non-negligible proportion of children survive without severe morbidity both at discharge and at 2-years' corrected age. Copyright © 2018 Elsevier Inc. All rights reserved.

Systematic Underestimation of Earthquake Magnitudes from Large Intracontinental Reverse Faults: Historical Ruptures Break Across Segment Boundaries

NASA Technical Reports Server (NTRS)

Rubin, C. M.

1996-01-01

Because most large-magnitude earthquakes along reverse faults have such irregular and complicated rupture patterns, reverse-fault segments defined on the basis of geometry alone may not be very useful for estimating sizes of future seismic sources. Most modern large ruptures of historical earthquakes generated by intracontinental reverse faults have involved geometrically complex rupture patterns. Ruptures across surficial discontinuities and complexities such as stepovers and cross-faults are common. Specifically, segment boundaries defined on the basis of discontinuities in surficial fault traces, pronounced changes in the geomorphology along strike, or the intersection of active faults commonly have not proven to be major impediments to rupture. Assuming that the seismic rupture will initiate and terminate at adjacent major geometric irregularities will commonly lead to underestimation of magnitudes of future large earthquakes.

EVALUATION OF CONTRAST-ENHANCED ULTRASONOGRAPHY AS A METHOD FOR DETECTING GALLBLADDER NECROSIS OR RUPTURE IN DOGS.

PubMed

Bargellini, Paolo; Orlandi, Riccardo; Paloni, Chiara; Rubini, Giuseppe; Fonti, Paolo; Peterson, Mark E; Rishniw, Mark; Boiti, Cristiano

2016-11-01

Gall bladder necrosis and rupture are life-threatening conditions in dogs requiring surgical intervention and early diagnosis is essential. Human patients with suspected gall bladder necrosis/rupture are commonly evaluated with contrast-enhanced ultrasonography (CEUS), however this procedure has not been described in dogs with suspected gall bladder necrosis/rupture. In a prospective diagnostic cohort study, CEUS (using SonoVue contrast medium) was performed in 93 dogs with gallbladder lesions identified by abdominal conventional ultrasonography. Necrosis/rupture was identified by CEUS as a focal lack of enhancement of the gallbladder wall. Dogs with positive CEUS finding for necrosis/rupture (complete lack of regional wall enhancement) underwent immediate surgery as did dogs with other biliary disorders requiring surgery. Dogs with negative CEUS findings or those not requiring surgery were managed medically. In cases undergoing surgery, necrosis/rupture was confirmed intraoperatively (and via histopathology). Absence of necrosis/rupture was confirmed either intraoperatively (via histopathology) or was assumed to be absent by complete recovery with medical management. Forty-nine dogs underwent surgery and cholecystectomy: 24 had necrosis/rupture. CEUS was more accurate (100% sensitive and specific) in diagnosing gallbladder wall necrosis/rupture than conventional ultrasonography (75% sensitive and 81% specific) (P < 0.03). In conclusion, CEUS provides accurate characterization of gallbladder wall integrity that can impact decisions regarding clinical management, either surgical or medical. © 2016 American College of Veterinary Radiology.

Induced seismicity provides insight into why earthquake ruptures stop

PubMed Central

Galis, Martin; Ampuero, Jean Paul; Mai, P. Martin; Cappa, Frédéric

2017-01-01

Injection-induced earthquakes pose a serious seismic hazard but also offer an opportunity to gain insight into earthquake physics. Currently used models relating the maximum magnitude of injection-induced earthquakes to injection parameters do not incorporate rupture physics. We develop theoretical estimates, validated by simulations, of the size of ruptures induced by localized pore-pressure perturbations and propagating on prestressed faults. Our model accounts for ruptures growing beyond the perturbed area and distinguishes self-arrested from runaway ruptures. We develop a theoretical scaling relation between the largest magnitude of self-arrested earthquakes and the injected volume and find it consistent with observed maximum magnitudes of injection-induced earthquakes over a broad range of injected volumes, suggesting that, although runaway ruptures are possible, most injection-induced events so far have been self-arrested ruptures. PMID:29291250

Size ratio correlates with intracranial aneurysm rupture status: a prospective study.

PubMed

Rahman, Maryam; Smietana, Janel; Hauck, Erik; Hoh, Brian; Hopkins, Nick; Siddiqui, Adnan; Levy, Elad I; Meng, Hui; Mocco, J

2010-05-01

The prediction of intracranial aneurysm (IA) rupture risk has generated significant controversy. The findings of the International Study of Unruptured Intracranial Aneurysms (ISUIA) that small anterior circulation aneurysms (<7 mm) have a 0% risk of subarachnoid hemorrhage in 5 years is difficult to reconcile with other studies that reported a significant portion of ruptured IAs are small. These discrepancies have led to the search for better aneurysm parameters to predict rupture. We previously reported that size ratio (SR), IA size divided by parent vessel diameter, correlated strongly with IA rupture status (ruptured versus unruptured). These data were all collected retrospectively off 3-dimensional angiographic images. Therefore, we performed a blinded prospective collection and evaluation of SR data from 2-dimensional angiographic images for a consecutive series of patients with ruptured and unruptured IAs. We prospectively enrolled 40 consecutive patients presenting to a single institution with either ruptured IA or for first-time evaluation of an incidental IA. Blinded technologists acquired all measurements from 2-dimensional angiographic images. Aneurysm rupture status, location, IA maximum size, and parent vessel diameter were documented. The SR was calculated by dividing the aneurysm size (mm) by the average parent vessel size (mm). A 2-tailed Mann-Whitney test was performed to assess statistical significance between ruptured and unruptured groups. Fisher exact test was used to compare medical comorbidities between the ruptured and unruptured groups. Significant differences between the 2 groups were subsequently tested with logistic regression. SE and probability values are reported. Forty consecutive patients with 24 unruptured and 16 ruptured aneurysms met the inclusion criteria. No significant differences were found in age, gender, smoking status, or medical comorbidities between ruptured and unruptured groups. The average maximum size of the unruptured IAs (6.18 + or - 0.60 mm) was significantly smaller compared with the ruptured IAs (7.91 + or - 0.47 mm; P=0.03), and the unruptured group had significantly smaller SRs (2.57 + or - 0.24 mm) compared with the ruptured group (4.08 + or - 0.54 mm; P<0.01). Logistic regression was used to evaluate the independent predictive value of those variables that achieved significance in univariate analysis (IA maximum size and SR). Using stepwise selection, only SR remained in the final predictive model (OR, 2.12; 95% CI, 1.09 to 4.13). SR, the ratio between aneurysm size and parent artery diameter, can be easily calculated from 2-dimensional angiograms and correlates with IA rupture status on presentation in a blinded analysis. SR should be further studied in a large prospective observational cohort to predict true IA risk of rupture.

Method for resonant measurement

DOEpatents

Rhodes, G.W.; Migliori, A.; Dixon, R.D.

1996-03-05

A method of measurement of objects to determine object flaws, Poisson`s ratio ({sigma}) and shear modulus ({mu}) is shown and described. First, the frequency for expected degenerate responses is determined for one or more input frequencies and then splitting of degenerate resonant modes are observed to identify the presence of flaws in the object. Poisson`s ratio and the shear modulus can be determined by identification of resonances dependent only on the shear modulus, and then using that shear modulus to find Poisson`s ratio using other modes dependent on both the shear modulus and Poisson`s ratio. 1 fig.

Role of intramural platelet thrombus in the pathogenesis of wall rupture and intra-ventricular thrombosis following acute myocardial infarction.

PubMed

Du, Xiao-Jun; Shan, Leonard; Gao, Xiao-Ming; Kiriazis, Helen; Liu, Yang; Lobo, Abhirup; Head, Geoffrey A; Dart, Anthony M

2011-02-01

Left ventricular thrombus (LVT) and rupture are important mechanical complications following myocardial infarction (MI) and are believed to be due to unrelated mechanisms. We studied whether, in fact, wall rupture and LVT are closely related in their pathogenesis with intramural platelet thrombus (IMT) playing a pivotal role. Male 129sv and C57Bl/6 mice underwent operation to induce MI, and autopsy was performed to confirm rupture deaths. Haemodynamic features of rupture events were monitored by telemetry in conscious mice. Detailed histological examination was conducted with special attention to the presence of IMT in relation to rupture location and LVT formation. IMT was detected in infarcted hearts of 129sv (82%) and C57Bl/6 (39%) mice with rupture in the form of a narrow streak spanning the wall or an occupying mass dissecting the infarcted myofibers apart. IMT often contained dense inflammatory cells and blood clot, indicating a dynamic process of thrombus formation and destruction. Notably, IMT was found extending into the cavity to form LVT. Haemodynamic monitoring by telemetry revealed that rupture occurred either as a single event or recurrent episodes. Importantly, the anti-platelet drug clopidogrel, but not aspirin, reduced the prevalence of rupture (10% vs. 45%) and IMT, and suppressed the degree of inflammation. Thus, IMT is a key pathological element in the infarcted heart closely associated with the complications of rupture and LVT. IMT could be either triggered by a wall tear or act as initiator of rupture. IMT may propagate towards the ventricular chamber to trigger LVT.

The persistence of directivity in small earthquakes

USGS Publications Warehouse

Boatwright, J.

2007-01-01

We derive a simple inversion of peak ground acceleration (PGA) or peak ground velocity (PGV) for rupture direction and rupture velocity and then test this inversion on the peak motions obtained from seven 3.5 ??? M ??? 4.1 earthquakes that occurred in two clusters in November 2002 and February 2003 near San Ramon, California. These clusters were located on two orthogonal strike-slip faults so that the events share the same approximate focal mechanism but not the same fault plane. Three earthquakes exhibit strong directivity, but the other four earthquakes exhibit relatively weak directivity. We use the residual PGAs and PGVs from the other six events to determine station corrections for each earthquake. The inferred rupture directions unambiguously identify the fault plane for the three earthquakes with strong directivity and for three of the four earthquakes with weak directivity. The events with strong directivity have fast rupture velocities (0.63????? v ??? 0.87??); the events with weak directivity either rupture more slowly (0.17????? v ???0.35??) or bilaterally. The simple unilateral inversion cannot distinguish between slow and bilateral ruptures: adding a bilateral rupture component degrades the fit of the rupture directions to the fault planes. By comparing PGAs from the events with strong and weak directivity, we show how an up-dip rupture in small events can distort the attenuation of peak ground motion with distance. When we compare the rupture directions of the earthquakes to the location of aftershocks in the two clusters, we find than almost all the aftershocks of the three earthquakes with strong directivity occur within 70?? of the direction of rupture.

Infectious mononucleosis presenting as spontaneous splenic rupture without other symptoms.

PubMed

Stockinger, Zsolt T

2003-09-01

Splenic rupture is an uncommon complication of infectious mononucleosis (IM), occurring in 0.1% to 0.5% of all patients. It remains the most common lethal complication of IM. Rupture of the spleen with no other symptoms of IM is almost unheard of. This is the report of a case of spontaneous splenic rupture requiring splenectomy in a patient with a positive heterophil antibody test and no other signs or symptoms of IM. The diagnosis and management of splenic rupture in IM are discussed.

The study of stiffness modulus values for AC-WC pavement

NASA Astrophysics Data System (ADS)

Lubis, AS; Muis, Z. A.; Iskandar, T. D.

2018-02-01

One of the parameters of the asphalt mixture in order for the strength and durability to be achieved as required is the stress-and-strain showing the stiffness of a material. Stiffness modulus is a very necessary factor that will affect the performance of asphalt pavements. If the stiffness modulus value decreases there will be a cause of aging asphalt pavement crack easily when receiving a heavy load. The high stiffness modulus asphalt concrete causes more stiff and resistant to bending. The stiffness modulus value of an asphalt mixture material can be obtained from the theoretical (indirect methods) and laboratory test results (direct methods). For the indirect methods used Brown & Brunton method, and Shell Bitumen method; while for the direct methods used the UMATTA tool. This study aims to determine stiffness modulus values for AC-WC pavement. The tests were conducted in laboratory that used 3 methods, i.e. Brown & Brunton Method, Shell Bitumen Method and Marshall Test as a substitute tool for the UMATTA tool. Hotmix asphalt made from type AC-WC with pen 60/70 using a mixture of optimum bitumen content was 5.84% with a standard temperature variation was 60°C and several variations of temperature that were 30, 40, 50, 70 and 80°C. The stiffness modulus value results obtained from Brown & Brunton Method, Shell Bitumen Method and Marshall Test which were 1374,93 Mpa, 235,45 Mpa dan 254,96 Mpa. The stiffness modulus value decreases with increasing temperature of the concrete asphalt. The stiffness modulus value from the Bitumen Shell method and the Marshall Test has a relatively similar value.The stiffness modulus value from the Brown & Brunton method is greater than the Bitumen Shell method and the Marshall Test, but can not measure the stiffness modulus value at temperature above 80°C.

Computational modeling of the effective Young's modulus values of fullerene molecules: a combined molecular dynamics simulation and continuum shell model.

PubMed

Ghavanloo, Esmaeal; Izadi, Razie; Nayebi, Ali

2018-02-28

Estimating the Young's modulus of a structure in the nanometer size range is a difficult task. The reliable determination of this parameter is, however, important in both basic and applied research. In this study, by combining molecular dynamics (MD) simulations and continuum shell theory, we designed a new approach to determining the Young's modulus values of different spherical fullerenes. The results indicate that the Young's modulus values of fullerene molecules decrease nonlinearly with increasing molecule size and understandably tend to the Young's modulus of an ideal flat graphene sheet at large molecular radii. To the best of our knowledge, this is first time that a combined atomistic-continuum method which can predict the Young's modulus values of fullerene molecules with high precision has been reported.

Time-resolved observation of thermally activated rupture of a capillary-condensed water nanobridge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bak, Wan; Sung, Baekman; Kim, Jongwoo

2015-01-05

The capillary-condensed liquid bridge is one of the most ubiquitous forms of liquid in nature and contributes significantly to adhesion and friction of biological molecules as well as microscopic objects. Despite its important role in nanoscience and technology, the rupture process of the bridge is not well understood and needs more experimental works. Here, we report real-time observation of rupture of a capillary-condensed water nanobridge in ambient condition. During slow and stepwise stretch of the nanobridge, we measured the activation time for rupture, or the latency time required for the bridge breakup. By statistical analysis of the time-resolved distribution ofmore » activation time, we show that rupture is a thermally activated stochastic process and follows the Poisson statistics. In particular, from the Arrhenius law that the rupture rate satisfies, we estimate the position-dependent activation energies for the capillary-bridge rupture.« less

A retrospective study of eyeball rupture in patients with or without orbital fracture

PubMed Central

Chen, Xiang; Yao, Yi; Wang, Fengxiang; Liu, Tiecheng; Zhao, Xiao

2017-01-01

Abstract To summarize the clinical features of eyeball rupture with or without orbital fracture and explore the differences between them. In all, 197 patients were observed, and the following data were recorded: sex, age, time of injury, place of injury, cause of trauma, zone of eye injury, intraocular content prolapse, surgical methods and the therapeutic process, visual acuity after injury, and the final best corrected visual acuity. The results were analyzed for statistically significant differences. There was no significant difference (P > .05) in the age, sex, or cause of injury. Patients with eyeball rupture with fracture had poorer vision than did those in the simple eyeball rupture group; eyeball rupture with fracture also had a higher probability of enucleation. In this study, the clinical results show that prognosis of eyeball rupture with orbital fracture is worse than that of eyeball rupture without orbital fracture. PMID:28614230

A retrospective study of eyeball rupture in patients with or without orbital fracture.

PubMed

Chen, Xiang; Yao, Yi; Wang, Fengxiang; Liu, Tiecheng; Zhao, Xiao

2017-06-01

To summarize the clinical features of eyeball rupture with or without orbital fracture and explore the differences between them.In all, 197 patients were observed, and the following data were recorded: sex, age, time of injury, place of injury, cause of trauma, zone of eye injury, intraocular content prolapse, surgical methods and the therapeutic process, visual acuity after injury, and the final best corrected visual acuity. The results were analyzed for statistically significant differences.There was no significant difference (P > .05) in the age, sex, or cause of injury. Patients with eyeball rupture with fracture had poorer vision than did those in the simple eyeball rupture group; eyeball rupture with fracture also had a higher probability of enucleation.In this study, the clinical results show that prognosis of eyeball rupture with orbital fracture is worse than that of eyeball rupture without orbital fracture.

Systematic observations of the slip pulse properties of large earthquake ruptures

USGS Publications Warehouse

Melgar, Diego; Hayes, Gavin

2017-01-01

In earthquake dynamics there are two end member models of rupture: propagating cracks and self-healing pulses. These arise due to different properties of faults and have implications for seismic hazard; rupture mode controls near-field strong ground motions. Past studies favor the pulse-like mode of rupture; however, due to a variety of limitations, it has proven difficult to systematically establish their kinematic properties. Here we synthesize observations from a database of >150 rupture models of earthquakes spanning M7–M9 processed in a uniform manner and show the magnitude scaling properties of these slip pulses indicates self-similarity. Further, we find that large and very large events are statistically distinguishable relatively early (at ~15 s) in the rupture process. This suggests that with dense regional geophysical networks strong ground motions from a large rupture can be identified before their onset across the source region.

Seismogenic width controls aspect ratios of earthquake ruptures

NASA Astrophysics Data System (ADS)

Weng, Huihui; Yang, Hongfeng

2017-03-01

We investigate the effect of seismogenic width on aspect ratios of earthquake ruptures by using numerical simulations of strike-slip faulting and an energy balance criterion near rupture tips. If the seismogenic width is smaller than a critical value, then ruptures cannot break the entire fault, regardless of the size of the nucleation zone. The seismic moments of these self-arresting ruptures increase with the nucleation size, forming nucleation-related events. The aspect ratios increase with the seismogenic width but are smaller than 8. In contrast, ruptures become breakaway and tend to have high aspect ratios (>8) if the seismogenic width is sufficiently large. But the critical nucleation size is larger than the theoretical estimate for an unbounded fault. The eventual seismic moments of breakaway ruptures do not depend on the nucleation size. Our results suggest that estimating final earthquake magnitude from the nucleation phase may only be plausible on faults with small seismogenic width.

Heterogeneous rupture on homogenous faults: Three-dimensional spontaneous rupture simulations with thermal pressurization

NASA Astrophysics Data System (ADS)

Urata, Yumi; Kuge, Keiko; Kase, Yuko

2008-11-01

To understand role of fluid on earthquake rupture processes, we investigated effects of thermal pressurization on spatial variation of dynamic rupture by computing spontaneous rupture propagation on a rectangular fault. We found thermal pressurization can cause heterogeneity of rupture even on a fault of uniform properties. On drained faults, tractions drop linearly with increasing slip in the same way everywhere. However, by changing the drained condition to an undrained one, the slip-weakening curves become non-linear and depend on locations on faults with small shear zone thickness w, and the dynamic frictional stresses vary spatially and temporally. Consequently, the super-shear transition fault length decreases for small w, and the final slip distribution can have some peaks regardless of w, especially on undrained faults. These effects should be taken into account of determining dynamic rupture parameters and modeling earthquake cycles when the presence of fluid is suggested in the source regions.

Considering the filler network as a third phase in polymer/CNT nanocomposites to predict the tensile modulus using Hashin-Hansen model

NASA Astrophysics Data System (ADS)

Kim, Sanghoon; Jamalzadeh, Navid; Zare, Yasser; Hui, David; Rhee, Kyong Yop

2018-07-01

In this paper, a conventional Hashin-Hansen model is developed to analyze the tensile modulus of polymer/CNT nanocomposites above the percolation threshold. This model for composites containing dispersed particles utilizes the aspect ratio of the nanofiller (α), the number of nanotubes per unit area (N), the percolation threshold (φp) and the modulus of the filler network (EN), assuming that the filler network constitutes a third phase in the nanocomposites. The experimental results and the predictions agree well, verifying the proposed relations between the modulus and the other parameters in the Hashin-Hansen model. Moreover, large values of "α", "N" and "EN" result in an improved modulus of the polymer/CNT nanocomposites, while a low percolation threshold results in a high modulus.

[Traumatic rupture of hepatic hydatid cyst].

PubMed

Martino, A; Rampone, B; Schiavone, B; Viviano, C; Cuomo, O; Iovine, L; Sacco, M; Maharajan, G; Confuorto, G

2010-01-01

Hydatid disease is endemic in some areas of the world. It is located mostly in the liver. The cysts rupture is possible after a trauma, or spontaneously by the increase of intracystic pressure. Rupture of the hydatid cyst requires urgent surgical intervention. We report our experience in treatment of traumatic rupture of hepatic hydatid cyst.

High-speed rupture during the initiation of the 2015 Bonin Islands deep earthquake

NASA Astrophysics Data System (ADS)

Zhan, Z.; Ye, L.; Shearer, P. M.; Lay, T.; Kanamori, H.

2015-12-01

Among the long-standing questions on how deep earthquakes rupture, the nucleation phase of large deep events is one of the most puzzling parts. Resolving the rupture properties of the initiation phase is difficult to achieve with far-field data because of the need for accurate corrections for structural effects on the waveforms (e.g., attenuation, scattering, and site effects) and alignment errors. Here, taking the 2015 Mw 7.9 Bonin Islands earthquake (depth = 678 km) as an example, we jointly invert its far-field P waves at multiple stations for the average rupture speed during the first second of the event. We use waveforms from a closely located aftershock as empirical Green's functions, and correct for possible differences in focal mechanisms and waveform misalignments with an iterative approach. We find that the average initial rupture speed is over 5 km/s, significantly higher than the average rupture speed of 3 km/s later in the event. This contrast suggests that rupture speeds of deep earthquakes can be highly variable during individual events and may define different stages of rupture, potentially with different mechanisms.

Partial achilles tendon rupture presenting with giant hematoma; MRI findings of 4 year follow up.

PubMed

Sarsilmaz, Aysegul; Varer, Makbule; Coskun, Gulten; Apaydın, Melda; Oyar, Orhan

2011-12-01

In the young population, spontaneous rupture of Achilles tendon is very rare. The big hematoma is also rare finding of the Achilles tendon partial rupture. It is usually seen with complete rupture. We presented imaging findings of 4 years follow up of the spontaneous partial rupture of Achilles tendon presenting with giant expanding hematoma and mimicking complete rupture radiologically. We discussed the alterations of tendon signal intensity and result of conservative therapy after partial rupture with big hematoma in the long term. A 29 year-old man, applied with pain and swelling in the retrocalcaneal region of left ankle. He did not have chronic metabolic disease. He was not active in physical activities. X-ray radiograms were normal. At magnetic resonance images (MRI), there was an intratendinous big hematoma, subcutanous fat planes were edematous around tendon. The diagnosis was partial rupture and giant hematoma. Hematoma was drained. The conservative treatment was applied and his complaints disappeared. After treatment, approximately 4 years later, control MRI showed thickened and hypointense tendon in all images. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Rupture history of 2008 May 12 Mw 8.0 Wen-Chuan earthquake: Evidence of slip interaction

NASA Astrophysics Data System (ADS)

Ji, C.; Shao, G.; Lu, Z.; Hudnut, K.; Jiu, J.; Hayes, G.; Zeng, Y.

2008-12-01

We will present the rupture process of the May 12, 2008 Mw 8.0 Wenchuan earthquake using all available data. The current model, using both teleseismic body and surface waves and interferometric LOS displacements, reveals an unprecedented complex rupture process which can not be resolved using either of the datasets individually. Rupture of this earthquake involved both the low angle Pengguan fault and the high angle Beichuan fault, which intersect each other at depth and are separated approximately 5-15 km at the surface. Rupture initiated on the Pengguan fault and triggered rupture on the Beichuan fault 10 sec later. The two faults dynamically interacted and unilaterally ruptured over 270 km with an average rupture velocity of 3.0 km/sec. The total seismic moment is 1.1x1021 Nm (Mw 8.0), roughly equally partitioned between the two faults. However, the spatiotemporal evaluations of the two faults are very different. This study will focus on the evidence for fault interactions and will analyze the corresponding uncertainties, in preparation for future dynamic studies of the same detailed nature.

Pulsed strain release on the Altyn Tagh fault, northwest China

USGS Publications Warehouse

Gold, Ryan D.; Cowgill, Eric; Arrowsmith, J. Ramón; Friedrich, Anke M.

2017-01-01

Earthquake recurrence models assume that major surface-rupturing earthquakes are followed by periods of reduced rupture probability as stress rebuilds. Although purely periodic, time- or slip-predictable rupture models are known to be oversimplifications, a paucity of long records of fault slip clouds understanding of fault behavior and earthquake recurrence over multiple ruptures. Here, we report a 16 kyr history of fault slip—including a pulse of accelerated slip from 6.4 to 6.0 ka—determined using a Monte Carlo analysis of well-dated offset landforms along the central Altyn Tagh strike-slip fault (ATF) in northwest China. This pulse punctuates a median rate of 8.1+1.2/−0.9 mm/a and likely resulted from either a flurry of temporally clustered ∼Mw 7.5 ground-rupturing earthquakes or a single large >Mw 8.2 earthquake. The clustered earthquake scenario implies rapid re-rupture of a fault reach >195 km long and indicates decoupled rates of elastic strain energy accumulation versus dissipation, conceptualized as a crustal stress battery. If the pulse reflects a single event, slip-magnitude scaling implies that it ruptured much of the ATF with slip similar to, or exceeding, the largest documented historical ruptures. Both scenarios indicate fault rupture behavior that deviates from classic time- or slip-predictable models.

Estimation of static parameters based on dynamical and physical properties in limestone rocks

NASA Astrophysics Data System (ADS)

Ghafoori, Mohammad; Rastegarnia, Ahmad; Lashkaripour, Gholam Reza

2018-01-01

Due to the importance of uniaxial compressive strength (UCS), static Young's modulus (ES) and shear wave velocity, it is always worth to predict these parameters from empirical relations that suggested for other formations with same lithology. This paper studies the physical, mechanical and dynamical properties of limestone rocks using the results of laboratory tests which carried out on 60 the Jahrum and the Asmari formations core specimens. The core specimens were obtained from the Bazoft dam site, hydroelectric supply and double-curvature arch dam in Iran. The Dynamic Young's modulus (Ed) and dynamic Poisson ratio were calculated using the existing relations. Some empirical relations were presented to estimate uniaxial compressive strength, as well as static Young's modulus and shear wave velocity (Vs). Results showed the static parameters such as uniaxial compressive strength and static Young's modulus represented low correlation with water absorption. It is also found that the uniaxial compressive strength and static Young's modulus had high correlation with compressional wave velocity and dynamic Young's modulus, respectively. Dynamic Young's modulus was 5 times larger than static Young's modulus. Further, the dynamic Poisson ratio was 1.3 times larger than static Poisson ratio. The relationship between shear wave velocity (Vs) and compressional wave velocity (Vp) was power and positive with high correlation coefficient. Prediction of uniaxial compressive strength based on Vp was better than that based on Vs . Generally, both UCS and static Young's modulus (ES) had good correlation with Ed.

Identification of vortex structures in a cohort of 204 intracranial aneurysms

PubMed Central

Trylesinski, Gabriel; Xiang, Jianping; Snyder, Kenneth; Meng, Hui

2017-01-01

An intracranial aneurysm (IA) is a cerebrovascular pathology that can lead to death or disability if ruptured. Abnormal wall shear stress (WSS) has been associated with IA growth and rupture, but little is known about the underlying flow physics related to rupture-prone IAs. Previous studies, based on analysis of a few aneurysms or partial views of three-dimensional vortex structures, suggest that rupture is associated with complex vortical flow inside IAs. To further elucidate the relevance of vortical flow in aneurysm pathophysiology, we studied 204 patient IAs (56 ruptured and 148 unruptured). Using objective quantities to identify three-dimensional vortex structures, we investigated the characteristics associated with aneurysm rupture and if these features correlate with previously proposed WSS and morphological characteristics indicative of IA rupture. Based on the Q-criterion definition of a vortex, we quantified the degree of the aneurysmal region occupied by vortex structures using the volume vortex fraction (vVF) and the surface vortex fraction (sVF). Computational fluid dynamics simulations showed that the sVF, but not the vVF, discriminated ruptured from unruptured aneurysms. Furthermore, we found that the near-wall vortex structures co-localized with regions of inflow jet breakdown, and significantly correlated to previously proposed haemodynamic and morphologic characteristics of ruptured IAs. PMID:28539480

Identification of vortex structures in a cohort of 204 intracranial aneurysms.

PubMed

Varble, Nicole; Trylesinski, Gabriel; Xiang, Jianping; Snyder, Kenneth; Meng, Hui

2017-05-01

An intracranial aneurysm (IA) is a cerebrovascular pathology that can lead to death or disability if ruptured. Abnormal wall shear stress (WSS) has been associated with IA growth and rupture, but little is known about the underlying flow physics related to rupture-prone IAs. Previous studies, based on analysis of a few aneurysms or partial views of three-dimensional vortex structures, suggest that rupture is associated with complex vortical flow inside IAs. To further elucidate the relevance of vortical flow in aneurysm pathophysiology, we studied 204 patient IAs (56 ruptured and 148 unruptured). Using objective quantities to identify three-dimensional vortex structures, we investigated the characteristics associated with aneurysm rupture and if these features correlate with previously proposed WSS and morphological characteristics indicative of IA rupture. Based on the Q -criterion definition of a vortex, we quantified the degree of the aneurysmal region occupied by vortex structures using the volume vortex fraction ( vVF ) and the surface vortex fraction ( sVF ). Computational fluid dynamics simulations showed that the sVF , but not the vVF , discriminated ruptured from unruptured aneurysms. Furthermore, we found that the near-wall vortex structures co-localized with regions of inflow jet breakdown, and significantly correlated to previously proposed haemodynamic and morphologic characteristics of ruptured IAs. © 2017 The Author(s).

Correlation between atmospheric pressure changes and abdominal aortic aneurysm rupture: results of a single-center study.

PubMed

Molacek, Jiri; Treska, Vladislav; Kasik, Miroslav; Houdek, Karel; Baxa, Jan

2013-09-01

There is much interest in all factors that influence the etiopathogenesis of abdominal aortic aneurysm (AAA) rupture. Apart from the well-established factors such as arterial hypertension, smoking, age, and genetic predisposition, less common factors that may play a role in the mechanism of the rupture are the subject of much discussion. These include atmospheric conditions, temperature, and atmospheric pressure. We conducted this study to investigate the effects of the absolute value of atmospheric pressure and its changes on the frequency of AAA rupture. We retrospectively examined 54 patients who underwent treatment for a ruptured AAA at the Clinic of Surgery in the University Hospital in Pilsen between 1 January 2005 and 31 December 2009. We collected data on the atmospheric pressure in this period from the Czech Hydrometeorological Institute in Pilsen. We did not find a significant difference in atmospheric pressure values between the days when the rupture occurred versus the other days (p < 0.5888). Moreover, we did not find significant changes in the atmospheric pressure during the 48 h preceding the rupture (Student's test p < 0.4434) versus the day of rupture or in the mean atmospheric pressure in that month. These findings suggest that atmospheric pressure and its changes do not affect the pathogenesis of AAA rupture.

Intrinsic, Transitional, and Extrinsic Morphological Factors Associated With Rupture of Intracranial Aneurysms.

PubMed

Ho, Allen L; Lin, Ning; Frerichs, Kai U; Du, Rose

2015-09-01

As diagnosis and treatment of unruptured intracranial aneurysms continues to increase, management principles remain largely based on size. This is despite mounting evidence that aneurysm location and other morphologic variables could play a role in predicting overall risk of rupture. Morphological parameters can be divided into 3 main groups, those that are intrinsic to the aneurysm, those that are extrinsic to the aneurysm, and those that involve both the aneurysm and surrounding vasculature (transitional). We present an evaluation of intrinsic, transitional, and extrinsic factors and their association with ruptured aneurysms. Using preoperative computed tomographic angiography, we generated 3-dimensional models of aneurysms and their surrounding vasculature with Slicer software. Using univariate and multivariate analyses, we examined the association of intrinsic, transitional, and extrinsic aspects of aneurysm morphology with rupture. Between 2005 and 2013, 227 cerebral aneurysms in 4 locations were evaluated/treated at a single institution, and computed tomographic angiographies of 218 patients (97 unruptured and 130 ruptured) were analyzed. Ruptured aneurysms analyzed were associated with clinical factors of absence of multiple aneurysms and history of no prior rupture, and morphologic factors of greater aspect ratio. On multivariate analysis, aneurysm rupture remained associated with history of no prior rupture, greater flow angle, greater daughter-daughter vessel angle, and smaller parent-daughter vessel angle. By studying the morphology of aneurysms and their surrounding vasculature, we identified several parameters associated with ruptured aneurysms that include intrinsic, transitional, and extrinsic factors of cerebral aneurysms and their surrounding vasculature.

A multiple fault rupture model of the November 13 2016, M 7.8 Kaikoura earthquake, New Zealand

NASA Astrophysics Data System (ADS)

Benites, R. A.; Francois-Holden, C.; Langridge, R. M.; Kaneko, Y.; Fry, B.; Kaiser, A. E.; Caldwell, T. G.

2017-12-01

The rupture-history of the November 13 2016 MW7.8 Kaikoura earthquake recorded by near- and intermediate-field strong-motion seismometers and 2 high-rate GPS stations reveals a complex cascade of multiple crustal fault rupture. In spite of such complexity, we show that the rupture history of each fault is well approximated by simple kinematic model with uniform slip and rupture velocity. Using 9 faults embedded in a crustal layer 19 km thick, each with a prescribed slip vector and rupture velocity, this model accurately reproduces the displacement waveforms recorded at the near-field strong-motion and GPS stations. This model includes the `Papatea Fault' with a mixed thrust and strike-slip mechanism based on in-situ geological observations with up to 8 m of uplift observed. Although the kinematic model fits the ground-motion at the nearest strong station, it doesn not reproduce the one sided nature of the static deformation field observed geodetically. This suggests a dislocation based approach does not completely capture the mechanical response of the Papatea Fault. The fault system as a whole extends for approximately 150 km along the eastern side of the Marlborough fault system in the South Island of New Zealand. The total duration of the rupture was 74 seconds. The timing and location of each fault's rupture suggests fault interaction and triggering resulting in a northward cascade crustal ruptures. Our model does not require rupture of the underlying subduction interface to explain the data.

Elastic modulus of phases in Ti–Mo alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Wei-dong; Liu, Yong, E-mail: yonliu11@aliyun.com; Wu, Hong

2015-08-15

In this work, a series of binary Ti–Mo alloys with the Mo contents ranging from 3.2 to 12 at.% were prepared using non-consumable arc melting. The microstructures were investigated by X-ray diffraction and transmission electron microscope, and the elastic modulus was evaluated by nanoindentation testing technique. The evolution of the volume fractions of ω phase was investigated using X-ray photoelectron spectroscopy. The results indicated that the phase constitution and elastic modulus of the Ti–Mo alloys are sensitive to the Mo content. Ti–3.2Mo and Ti–8Mo alloys containing only α and β phases, respectively, have a low elastic modulus. In contrast, Ti–4.5Mo,more » Ti–6Mo, Ti–7Mo alloys, with different contents of ω phase, have a high elastic modulus. A simple micromechanical model was used to calculate the elastic modulus of ω phase (E{sub ω}), which was determined to be 174.354 GPa. - Highlights: • Ti–Mo alloys with the Mo contents ranging from 3.2 to 12 at.% were investigated. • XPS was used to investigate the volume fractions of ω phase. • The elastic modulus of Ti–Mo alloys is sensitive to the Mo content. • The elastic modulus of ω phase was determined to be 174.354 GPa.« less

Spontaneous splenic rupture in an active duty Marine upon return from Iraq: a case report

PubMed Central

2010-01-01

Introduction Atraumatic splenic rupture is a rare event that has been associated with several infectious disease processes. In the active duty military population, potential exposure to these pathogens is significant. Here we discuss the case of an active duty Marine with spontaneous splenic rupture upon return from a six-month deployment in Iraq. Case presentation A previously healthy 30-year-old Caucasian male active duty Marine presented with abdominal pain, fever and diarrhea after deployment to Iraq in support of Operation Iraqi Freedom. Based on clinical and radiographic evidence, a diagnosis of spontaneous splenic rupture was ultimately suspected. After exploratory laparotomy with confirmation of rupture, splenectomy was performed, and the patient made a full, uneventful recovery. Histopathologic examination revealed mild splenomegaly with a ruptured capsule of undetermined cause. Conclusion Spontaneous splenic rupture is a rare event that may lead to life-threatening hemorrhage if not diagnosed and treated quickly. Although the cause of this patient's case was unknown, atraumatic splenic rupture has been associated with a variety of infectious diseases and demonstrates some risks the active duty military population may face while on deployment. Having an awareness of these pathogens and their role in splenic rupture, clinicians caring for military personnel must be prepared to recognize and treat this potentially fatal complication. PMID:21054871

Dynamic rupture modeling of thrust faults with parallel surface traces.

NASA Astrophysics Data System (ADS)

Peshette, P.; Lozos, J.; Yule, D.

2017-12-01

Fold and thrust belts (such as those found in the Himalaya or California Transverse Ranges) consist of many neighboring thrust faults in a variety of geometries. Active thrusts within these belts individually contribute to regional seismic hazard, but further investigation is needed regarding the possibility of multi-fault rupture in a single event. Past analyses of historic thrust surface traces suggest that rupture within a single event can jump up to 12 km. There is also observational precedent for long distance triggering between subparallel thrusts (e.g. the 1997 Harnai, Pakistan events, separated by 50 km). However, previous modeling studies find a maximum jumping rupture distance between thrust faults of merely 200 m. Here, we present a new dynamic rupture modeling parameter study that attempts to reconcile these differences and determine which geometrical and stress conditions promote jumping rupture. We use a community verified 3D finite element method to model rupture on pairs of thrust faults with parallel surface traces. We vary stress drop and fault strength to determine which conditions produce jumping rupture at different dip angles and different separations between surface traces. This parameter study may help to understand the likelihood of jumping rupture in real-world thrust systems, and may thereby improve earthquake hazard assessment.

Pseudo-dynamic source characterization accounting for rough-fault effects

NASA Astrophysics Data System (ADS)

Galis, Martin; Thingbaijam, Kiran K. S.; Mai, P. Martin

2016-04-01

Broadband ground-motion simulations, ideally for frequencies up to ~10Hz or higher, are important for earthquake engineering; for example, seismic hazard analysis for critical facilities. An issue with such simulations is realistic generation of radiated wave-field in the desired frequency range. Numerical simulations of dynamic ruptures propagating on rough faults suggest that fault roughness is necessary for realistic high-frequency radiation. However, simulations of dynamic ruptures are too expensive for routine applications. Therefore, simplified synthetic kinematic models are often used. They are usually based on rigorous statistical analysis of rupture models inferred by inversions of seismic and/or geodetic data. However, due to limited resolution of the inversions, these models are valid only for low-frequency range. In addition to the slip, parameters such as rupture-onset time, rise time and source time functions are needed for complete spatiotemporal characterization of the earthquake rupture. But these parameters are poorly resolved in the source inversions. To obtain a physically consistent quantification of these parameters, we simulate and analyze spontaneous dynamic ruptures on rough faults. First, by analyzing the impact of fault roughness on the rupture and seismic radiation, we develop equivalent planar-fault kinematic analogues of the dynamic ruptures. Next, we investigate the spatial interdependencies between the source parameters to allow consistent modeling that emulates the observed behavior of dynamic ruptures capturing the rough-fault effects. Based on these analyses, we formulate a framework for pseudo-dynamic source model, physically consistent with the dynamic ruptures on rough faults.

The evolution of slip pulses within bimaterial interfaces with rupture velocity

NASA Astrophysics Data System (ADS)

Shlomai, H.; Fineberg, J.

2017-12-01

The most general frictional motion in nature involves bimaterial interfaces, when contacting bodies possess different elastic properties. Frictional motion occurs when the contacts composing the interface separating these bodies detach via propagating rupture fronts. Coupling between slip and normal stress variations is unique to bimaterial interfaces. Here we use high speed simultaneous measurements of slip velocities, real contact area and stresses to explicitly reveal this bimaterial coupling and its role in determining different classes of rupture modes and their structures. Our experiments study the rupture of a spatially extended interface formed by brittle plastics whose shear wave speeds differ by 30%. Any slip within a bimaterial interface will break the stress symmetry across the interface. One important result of this is that local values of normal stress variations at the interface couple to interface slip, `bimaterial coupling'. The sign of the coupling depends on the front propagation direction. When we consider ruptures propagating in the direction of motion of the more compliant material, the `positive' direction, slip reduces the normal stress. We focus on this direction. We show that, in this direction, interface ruptures develop from crack-like behavior at low rupture velocities, whose structure corresponds to theoretical predictions: As the ruptures accelerate towards their asymptotic speed, the structures of the strain and stress fields near the rupture tip deviate significantly from this crack-like form, and systematically sharpen to a pulse-like rupture mode called slip-pulses. We conclude with a description of slip-pulse properties.

Modeling 3D Dynamic Rupture on Arbitrarily-Shaped faults by Boundary-Conforming Finite Difference Method

NASA Astrophysics Data System (ADS)

Zhu, D.; Zhu, H.; Luo, Y.; Chen, X.

2008-12-01

We use a new finite difference method (FDM) and the slip-weakening law to model the rupture dynamics of a non-planar fault embedded in a 3-D elastic media with free surface. The new FDM, based on boundary- conforming grid, sets up the mapping equations between the curvilinear coordinate and the Cartesian coordinate and transforms irregular physical space to regular computational space; it also employs a higher- order non-staggered DRP/opt MacCormack scheme which is of low dispersion and low dissipation so that the high accuracy and stability of our rupture modeling are guaranteed. Compared with the previous methods, not only we can compute the spontaneous rupture of an arbitrarily shaped fault, but also can model the influence of the surface topography on the rupture process of earthquake. In order to verify the feasibility of this method, we compared our results and other previous results, and found out they matched perfectly. Thanks to the boundary-conforming FDM, problems such as dynamic rupture with arbitrary dip, strike and rake over an arbitrary curved plane can be handled; and supershear or subshear rupture can be simulated with different parameters such as the initial stresses and the critical slip displacement Dc. Besides, our rupture modeling is economical to be implemented owing to its high efficiency and does not suffer from displacement leakage. With the help of inversion data of rupture by field observations, this method is convenient to model rupture processes and seismograms of natural earthquakes.

Aetiology and pathogenesis of cranial cruciate ligament rupture in cats by histological examination.

PubMed

Wessely, Marlis; Reese, Sven; Schnabl-Feichter, Eva

2017-06-01

Objectives The aim of this study was to examine histologically intact and ruptured cranial cruciate ligaments in cats, in order to evaluate whether degeneration is a prerequisite for rupture. Methods We performed a histological examination of 50 intact and 19 ruptured cranial cruciate ligaments in cadaver or client-owned cats, respectively, using light microscopy. Cats with stifle pathology were further divided into five age groups in order to investigate the relationship of changes in the ligament with lifespan. Cats with ruptured cranial cruciate ligaments were divided into two groups according to medical history (with presumed history of trauma or without any known history of trauma) in order to investigate the relationship of ligament rupture with a traumatic event. Data from 200 healthy cats were selected randomly and reviewed to make a statistical comparison of cats with and without cranial cruciate ligament rupture (reference group). Results On histological examination, the intact cranial cruciate ligaments showed basic parallel arrangement of the collagen fibres, with no relation to age. While cats of a more advanced age showed fibrocartilage in the middle of the cranial cruciate ligament - a likely physiological reaction to compression forces over the lifespan - degenerative changes within the fibrocartilage were absent in all cases, regardless of age or rupture status. Cats suffering from cranial cruciate ligament rupture without history of trauma were significantly older than cats in the reference group. Conclusions and relevance This study showed that differentiation of fibrocartilage in the middle of the cranial cruciate ligament is likely a physiological reaction to compressive forces and not a degenerative change associated with greater risk of rupture in advanced age. This finding in cats is distinct from the known decrease in differentiation of fibrocartilage in dogs with cranial cruciate ligament rupture. Furthermore, the histological examination of cats revealed no other signs of degeneration in the cranial cruciate ligaments. Thus, degeneration is likely not an aetiological factor for cranial cruciate ligament rupture in cats.

Endocytic vesicle rupture is a conserved mechanism of cellular invasion by amyloid proteins.

PubMed

Flavin, William P; Bousset, Luc; Green, Zachary C; Chu, Yaping; Skarpathiotis, Stratos; Chaney, Michael J; Kordower, Jeffrey H; Melki, Ronald; Campbell, Edward M

2017-10-01

Numerous pathological amyloid proteins spread from cell to cell during neurodegenerative disease, facilitating the propagation of cellular pathology and disease progression. Understanding the mechanism by which disease-associated amyloid protein assemblies enter target cells and induce cellular dysfunction is, therefore, key to understanding the progressive nature of such neurodegenerative diseases. In this study, we utilized an imaging-based assay to monitor the ability of disease-associated amyloid assemblies to rupture intracellular vesicles following endocytosis. We observe that the ability to induce vesicle rupture is a common feature of α-synuclein (α-syn) assemblies, as assemblies derived from WT or familial disease-associated mutant α-syn all exhibited the ability to induce vesicle rupture. Similarly, different conformational strains of WT α-syn assemblies, but not monomeric or oligomeric forms, efficiently induced vesicle rupture following endocytosis. The ability to induce vesicle rupture was not specific to α-syn, as amyloid assemblies of tau and huntingtin Exon1 with pathologic polyglutamine repeats also exhibited the ability to induce vesicle rupture. We also observe that vesicles ruptured by α-syn are positive for the autophagic marker LC3 and can accumulate and fuse into large, intracellular structures resembling Lewy bodies in vitro. Finally, we show that the same markers of vesicle rupture surround Lewy bodies in brain sections from PD patients. These data underscore the importance of this conserved endocytic vesicle rupture event as a damaging mechanism of cellular invasion by amyloid assemblies of multiple neurodegenerative disease-associated proteins, and suggest that proteinaceous inclusions such as Lewy bodies form as a consequence of continued fusion of autophagic vesicles in cells unable to degrade ruptured vesicles and their amyloid contents.

The 1994 Northridge, California, earthquake: Investigation of rupture velocity, risetime, and high-frequency radiation

USGS Publications Warehouse

Hartzell, S.; Liu, P.; Mendoza, C.

1996-01-01

A hybrid global search algorithm is used to solve the nonlinear problem of calculating slip amplitude, rake, risetime, and rupture time on a finite fault. Thirty-five strong motion velocity records are inverted by this method over the frequency band from 0.1 to 1.0 Hz for the Northridge earthquake. Four regions of larger-amplitude slip are identified: one near the hypocenter at a depth of 17 km, a second west of the hypocenter at about the same depth, a third updip from the hypocenter at a depth of 10 km, and a fourth updip from the hypocenter and to the northwest. The results further show an initial fast rupture with a velocity of 2.8 to 3.0 km/s followed by a slow termination of the rupture with velocities of 2.0 to 2.5 km/s. The initial energetic rupture phase lasts for 3 s, extending out 10 km from the hypocenter. Slip near the hypocenter has a short risetime of 0.5 s, which increases to 1.5 s for the major slip areas removed from the hypocentral region. The energetic rupture phase is also shown to be the primary source of high-frequency radiation (1-15 Hz) by an inversion of acceleration envelopes. The same global search algorithm is used in the envelope inversion to calculate high-frequency radiation intensity on the fault and rupture time. The rupture timing from the low- and high-frequency inversions is similar, indicating that the high frequencies are produced primarily at the mainshock rupture front. Two major sources of high-frequency radiation are identified within the energetic rupture phase, one at the hypocenter and another deep source to the west of the hypocenter. The source at the hypocenter is associated with the initiation of rupture and the breaking of a high-stress-drop asperity and the second is associated with stopping of the rupture in a westerly direction.

Effect of position, time in the season, and playing surface on Achilles tendon ruptures in NFL games: a 2009-10 to 2016-17 review.

PubMed

Krill, Michael K; Borchers, James R; Hoffman, Joshua T; Krill, Matthew L; Hewett, Timothy E

2017-09-01

Achilles tendon (AT) ruptures are a potentially career-altering and ending injury. Achilles tendon ruptures have a below average return-to-play rate compared to other common orthopaedic procedures for National Football League (NFL) players. The objective of this study was to monitor the incidence and injury rates (IR) of AT ruptures that occurred during the regular season in order to evaluate the influence of player position, time of injury, and playing surface on rupture rates. A thorough online review was completed to identify published injury reports and public information regarding AT ruptures sustained during regular season and post-season games in the National Football League (NFL) during the 2009-10 to 2016-17 seasons. Team schedules, player position details and stadium information was used to determine period of the season of injury and playing surface. IRs were calculated per 100 team games (TG). Injury rate ratios (IRR) were utilized to compare IRs. During eight monitored seasons, there were 44 AT ruptures in NFL games. A majority of AT ruptures were sustained in the first eight games of the regular season (n = 32, 72.7%). There was a significant rate difference for the first and second four-game segments of the regular season compared to the last two four-game segments of the regular season. Defensive players suffered a majority of AT ruptures (n = 32, 72.7%). The IR on grass was 1.00 per 100 TG compared to 1.08 per 100 TG on artificial turf (IRR: 0.93, p = .80). A significant increase in AT ruptures occurred in the first and second four game segments of the regular season compared to the last two-four game segments of the regular season. Defensive players suffered a majority of AT ruptures compared to offensive or specialist players. There was no difference between AT rupture rates and playing surface in games.

Rupture Following Biceps-to-Triceps Tendon Transfer in Adolescents and Young Adults With Spinal Cord Injury:

PubMed Central

Merenda, Lisa A.; Rutter, Laure; Curran, Kimberly; Kozin, Scott H.

2012-01-01

Background: Tendon transfer surgery can restore elbow extension in approximately 70% of persons with tetraplegia and often results in antigravity elbow extension strength. However, we have noted an almost 15% rupture/attenuation rate. Objective: This investigation was conducted to analyze potential causes in adolescents/young adults with spinal cord injury (SCI) who experienced tendon rupture or attenuation after biceps-to-triceps transfer. Methods: Medical charts of young adults with SCI who underwent biceps-to-triceps transfer and experienced tendon rupture or attenuation were reviewed. Data collected by retrospective chart review included general demographics, surgical procedure(s), use and duration of antibiotic treatment, time from tendon transfer surgery to rupture/attenuation, and method of diagnosis. Results: Twelve subjects with tetraplegia (mean age, 19 years) who underwent biceps-to-triceps reconstruction with subsequent tendon rupture or attenuation were evaluated. Mean age at time of tendon transfer was 18 years (range, 14-21 years). A fluoroquinolone was prescribed for 42% (n=5) of subjects. Tendon rupture was noted in 67% (n=8), and attenuation was noted in 33% (n=4). Average length of time from surgery to tendon rupture/attenuation was 5.7 months (range, 3-10 months). Conclusion: Potential contributing causes of tendon rupture/attenuation after transfer include surgical technique, rehabilitation, co-contraction of the transfer, poor patient compliance, and medications. In this cohort, 5 subjects were prescribed fluoroquinolones that have a US Food and Drug Administration black box concerning tendon ruptures. Currently, all candidates for upper extremity tendon transfer reconstruction are counseled on the effects of fluoroquinolones and the potential risk for tendon rupture. PMID:23459326

Diverse rupture processes in the 2015 Peru deep earthquake doublet.

PubMed

Ye, Lingling; Lay, Thorne; Kanamori, Hiroo; Zhan, Zhongwen; Duputel, Zacharie

2016-06-01

Earthquakes in deeply subducted oceanic lithosphere can involve either brittle or dissipative ruptures. On 24 November 2015, two deep (606 and 622 km) magnitude 7.5 and 7.6 earthquakes occurred 316 s and 55 km apart. The first event (E1) was a brittle rupture with a sequence of comparable-size subevents extending unilaterally ~50 km southward with a rupture speed of ~4.5 km/s. This earthquake triggered several aftershocks to the north along with the other major event (E2), which had 40% larger seismic moment and the same duration (~20 s), but much smaller rupture area and lower rupture speed than E1, indicating a more dissipative rupture. A minor energy release ~12 s after E1 near the E2 hypocenter, possibly initiated by the S wave from E1, and a clear aftershock ~165 s after E1 also near the E2 hypocenter, suggest that E2 was likely dynamically triggered. Differences in deep earthquake rupture behavior are commonly attributed to variations in thermal state between subduction zones. However, the marked difference in rupture behavior of the nearby Peru doublet events suggests that local variations of stress state and material properties significantly contribute to diverse behavior of deep earthquakes.

Risk Factors for the Rupture of Intracranial Aneurysms Using Computed Tomography Angiography.

PubMed

Wang, Guang-Xian; Wen, Li; Yang, Liu; Zhang, Qi-Chuang; Yin, Jin-Bo; Duan, Chun-Mei; Zhang, Dong

2018-02-01

To study the clinical and morphologic characteristics associated with risk factors for the rupture of intracranial aneurysms (IAs). A total of 1115 consecutive patients with 1282 IAs were reviewed from August 2011 to February 2016. The patients and IAs were divided into ruptured and unruptured groups. Based on the clinical and morphologic findings, the risk factors for IA rupture were assessed using statistical methods. Age, hypertension, diabetes mellitus, and cerebral atherosclerosis were associated with ruptured IAs. IAs located in the anterior cerebral artery, the anterior communicating artery, the posterior communicating artery, and the internal carotid artery were associated with ruptured IAs. Ruptures were also associated with arterial bifurcations, irregular aneurysm shapes, and all continuous data, except neck width. Binary logistic regression showed that IAs located at bifurcations (odds ratio [OR], 1.804), with irregular shapes (OR, 4.677), with high aspect ratios (ARs) (OR, 5.037) or with small mean diameters (MDs) (OR, 0.495) are more prone to rupture. Receiver operating characteristic analysis showed that the threshold values of the AR and MD were 1 and 3.70 mm, respectively. Morphologic characteristics, such as being located at bifurcations, being irregularly shaped, having a high AR (>1), and having a small MD (<3.70 mm), were better predictors of rupture. Copyright © 2017 Elsevier Inc. All rights reserved.

Three-Dimensional Dynamic Rupture in Brittle Solids and the Volumetric Strain Criterion

NASA Astrophysics Data System (ADS)

Uenishi, K.; Yamachi, H.

2017-12-01

As pointed out by Uenishi (2016 AGU Fall Meeting), source dynamics of ordinary earthquakes is often studied in the framework of 3D rupture in brittle solids but our knowledge of mechanics of actual 3D rupture is limited. Typically, criteria derived from 1D frictional observations of sliding materials or post-failure behavior of solids are applied in seismic simulations, and although mode-I cracks are frequently encountered in earthquake-induced ground failures, rupture in tension is in most cases ignored. Even when it is included in analyses, the classical maximum principal tensile stress rupture criterion is repeatedly used. Our recent basic experiments of dynamic rupture of spherical or cylindrical monolithic brittle solids by applying high-voltage electric discharge impulses or impact loads have indicated generation of surprisingly simple and often flat rupture surfaces in 3D specimens even without the initial existence of planes of weakness. However, at the same time, the snapshots taken by a high-speed digital video camera have shown rather complicated histories of rupture development in these 3D solid materials, which seem to be difficult to be explained by, for example, the maximum principal stress criterion. Instead, a (tensile) volumetric strain criterion where the volumetric strain (dilatation or the first invariant of the strain tensor) is a decisive parameter for rupture seems more effective in computationally reproducing the multi-directionally propagating waves and rupture. In this study, we try to show the connection between this volumetric strain criterion and other classical rupture criteria or physical parameters employed in continuum mechanics, and indicate that the criterion has, to some degree, physical meanings. First, we mathematically illustrate that the criterion is equivalent to a criterion based on the mean normal stress, a crucial parameter in plasticity. Then, we mention the relation between the volumetric strain criterion and the failure envelope of the Mohr-Coulomb criterion that describes shear-related rupture. The critical value of the volumetric strain for rupture may be controlled by the apparent cohesion and apparent angle of internal friction of the Mohr-Coulomb criterion.

Retrieving rupture history using waveform inversions in time sequence

NASA Astrophysics Data System (ADS)

Yi, L.; Xu, C.; Zhang, X.

2017-12-01

The rupture history of large earthquakes is generally regenerated using the waveform inversion through utilizing seismological waveform records. In the waveform inversion, based on the superposition principle, the rupture process is linearly parameterized. After discretizing the fault plane into sub-faults, the local source time function of each sub-fault is usually parameterized using the multi-time window method, e.g., mutual overlapped triangular functions. Then the forward waveform of each sub-fault is synthesized through convoluting the source time function with its Green function. According to the superposition principle, these forward waveforms generated from the fault plane are summarized in the recorded waveforms after aligning the arrival times. Then the slip history is retrieved using the waveform inversion method after the superposing of all forward waveforms for each correspond seismological waveform records. Apart from the isolation of these forward waveforms generated from each sub-fault, we also realize that these waveforms are gradually and sequentially superimposed in the recorded waveforms. Thus we proposed a idea that the rupture model is possibly detachable in sequent rupture times. According to the constrained waveform length method emphasized in our previous work, the length of inverted waveforms used in the waveform inversion is objectively constrained by the rupture velocity and rise time. And one essential prior condition is the predetermined fault plane that limits the duration of rupture time, which means the waveform inversion is restricted in a pre-set rupture duration time. Therefore, we proposed a strategy to inverse the rupture process sequentially using the progressively shift rupture times as the rupture front expanding in the fault plane. And we have designed a simulation inversion to test the feasibility of the method. Our test result shows the prospect of this idea that requiring furthermore investigation.

Geologic and structural controls on rupture zone fabric: A field-based study of the 2010 Mw 7.2 El Mayor–Cucapah earthquake surface rupture

USGS Publications Warehouse

Teran, Orlando; Fletcher, John L.; Oskin, Michael; Rockwell, Thomas; Hudnut, Kenneth W.; Spelz, Ronald; Akciz, Sinan; Hernandez-Flores, Ana Paula; Morelan, Alexander

2015-01-01

We systematically mapped (scales >1:500) the surface rupture of the 4 April 2010 Mw (moment magnitude) 7.2 El Mayor-Cucapah earthquake through the Sierra Cucapah (Baja California, northwestern Mexico) to understand how faults with similar structural and lithologic characteristics control rupture zone fabric, which is here defined by the thickness, distribution, and internal configuration of shearing in a rupture zone. Fault zone thickness and master fault dip are strongly correlated with many parameters of rupture zone fabric. Wider fault zones produce progressively wider rupture zones and both of these parameters increase systematically with decreasing dip of master faults, which varies from 20° to 90° in our dataset. Principal scarps that accommodate more than 90% of the total coseismic slip in a given transect are only observed in fault sections with narrow rupture zones (<25 m). As rupture zone thickness increases, the number of scarps in a given transect increases, and the scarp with the greatest relative amount of coseismic slip decreases. Rupture zones in previously undeformed alluvium become wider and have more complex arrangements of secondary fractures with oblique slip compared to those with pure normal dip-slip or pure strike-slip. Field relations and lidar (light detection and ranging) difference models show that as magnitude of coseismic slip increases from 0 to 60 cm, the links between kinematically distinct fracture sets increase systematically to the point of forming a throughgoing principal scarp. Our data indicate that secondary faults and penetrative off-fault strain continue to accommodate the oblique kinematics of coseismic slip after the formation of a thoroughgoing principal scarp. Among the widest rupture zones in the Sierra Cucapah are those developed above buried low angle faults due to the transfer of slip to widely distributed steeper faults, which are mechanically more favorably oriented. The results from this study show that the measureable parameters that define rupture zone fabric allow for testing hypotheses concerning the mechanics and propagation of earthquake ruptures, as well as for siting and designing facilities to be constructed in regions near active faults.

Microvessel rupture induced by high-intensity therapeutic ultrasound-a study of parameter sensitivity in a simple in vivo model.

PubMed

Kim, Yeonho; Nabili, Marjan; Acharya, Priyanka; Lopez, Asis; Myers, Matthew R

2017-01-01

Safety analyses of transcranial therapeutic ultrasound procedures require knowledge of the dependence of the rupture probability and rupture time upon sonication parameters. As previous vessel-rupture studies have concentrated on a specific set of exposure conditions, there is a need for more comprehensive parametric studies. Probability of rupture and rupture times were measured by exposing the large blood vessel of a live earthworm to high-intensity focused ultrasound pulse trains of various characteristics. Pressures generated by the ultrasound transducers were estimated through numerical solutions to the KZK (Khokhlov-Zabolotskaya-Kuznetsov) equation. Three ultrasound frequencies (1.1, 2.5, and 3.3 MHz) were considered, as were three pulse repetition frequencies (1, 3, and 10 Hz), and two duty factors (0.0001, 0.001). The pressures produced ranged from 4 to 18 MPa. Exposures of up to 10 min in duration were employed. Trials were repeated an average of 11 times. No trends as a function of pulse repetition rate were identifiable, for either probability of rupture or rupture time. Rupture time was found to be a strong function of duty factor at the lower pressures; at 1.1 MHz the rupture time was an order of magnitude lower for the 0.001 duty factor than the 0.0001. At moderate pressures, the difference between the duty factors was less, and there was essentially no difference between duty factors at the highest pressure. Probability of rupture was not found to be a strong function of duty factor. Rupture thresholds were about 4 MPa for the 1.1 MHz frequency, 7 MPa at 3.3 MHz, and 11 MPa for the 2.5 MHz, though the pressure value at 2.5 MHz frequency will likely be reduced when steep-angle corrections are accounted for in the KZK model used to estimate pressures. Mechanical index provided a better collapse of the data (less separation of the curves pertaining to the different frequencies) than peak negative pressure, for both probability of rupture and rupture time. The results provide a database with which investigations in more complex animal models can be compared, potentially establishing trends by which bioeffects in human vessels can be estimated.

Risk factors for achilles tendon rupture: A matched case control study.

PubMed

Noback, Peter C; Jang, Eugene S; Cuellar, Derly O; Seetharaman, Mani; Malagoli, Emiliano; Greisberg, Justin K; Vosseller, J Turner

2017-10-01

The purpose of this study was to elucidate whether body mass index (BMI), activity level, and other risk factors predispose patients to Achilles tendon ruptures. A retrospective review of 279 subjects was performed (93 with Achilles tendon rupture, matched 1:2 with 186 age/sex matched controls with ankle sprains). Demographic variables and risk factors for rupture were tabulated and compared. The rupture group mean BMI was 27.77 (95% CI, 26.94-28.49), and the control group mean BMI was 26.66 (95% CI, 26.06-27.27). These populations were found to be statistically equivalent (p=0.047 and p<0.001 by two one-sided t-test). A significantly higher proportion of those suffering ruptures reported regular athletic activity at baseline (74%) versus controls (59%, p=0.013). There was no clinically significant difference found in BMI between patients with ruptures and controls. Furthermore, it was found that patients who sustained ruptures were also more likely to be active at baseline than their ankle sprain counterparts. Copyright © 2017 Elsevier Ltd. All rights reserved.

Shigella subverts the host recycling compartment to rupture its vacuole.

PubMed

Mellouk, Nora; Weiner, Allon; Aulner, Nathalie; Schmitt, Christine; Elbaum, Michael; Shorte, Spencer L; Danckaert, Anne; Enninga, Jost

2014-10-08

Shigella enters epithlial cells via internalization into a vacuole. Subsequent vacuolar membrane rupture allows bacterial escape into the cytosol for replication and cell-to-cell spread. Bacterial effectors such as IpgD, a PI(4,5)P2 phosphatase that generates PI(5)P and alters host actin, facilitate this internalization. Here, we identify host proteins involved in Shigella uptake and vacuolar membrane rupture by high-content siRNA screening and subsequently focus on Rab11, a constituent of the recycling compartment. Rab11-positive vesicles are recruited to the invasion site before vacuolar rupture, and Rab11 knockdown dramatically decreases vacuolar membrane rupture. Additionally, Rab11 recruitment is absent and vacuolar rupture is delayed in the ipgD mutant that does not dephosphorylate PI(4,5)P₂ into PI(5)P. Ultrastructural analyses of Rab11-positive vesicles further reveal that ipgD mutant-containing vacuoles become confined in actin structures that likely contribute to delayed vacular rupture. These findings provide insight into the underlying molecular mechanism of vacuole progression and rupture during Shigella invasion. Copyright © 2014 Elsevier Inc. All rights reserved.

Broadband Rupture Process of the 2001 Kunlun Fault (Mw 7.8) Earthquake

NASA Astrophysics Data System (ADS)

Antolik, M.; Abercrombie, R.; Ekstrom, G.

2003-04-01

We model the source process of the 14 November, 2001 Kunlun fault earthquake using broadband body waves from the Global Digital Seismographic Network (P, SH) and both point-source and distributed slip techniques. The point-source mechanism technique is a non-linear iterative inversion that solves for focal mechanism, moment rate function, depth, and rupture directivity. The P waves reveal a complex rupture process for the first 30 s, with smooth unilateral rupture toward the east along the Kunlun fault accounting for the remainder of the 120 s long rupture. The obtained focal mechanism for the main portion of the rupture is (strike=96o, dip=83o, rake=-8o) which is consistent with both the Harvard CMT solution and observations of the surface rupture. The seismic moment is 5.29×1020 Nm and the average rupture velocity is ˜3.5 km/s. However, the initial portion of the P waves cannot be fit at all with this mechanism. A strong pulse visible in the first 20 s can only be matched with an oblique-slip subevent (MW ˜ 6.8-7.0) involving a substantial normal faulting component, but the nodal planes of this mechanism are not well constrained. The first-motion polarities of the P waves clearly require a strike mechanism with a similar orientation as the Kunlun fault. Field observations of the surface rupture (Xu et al., SRL, 73, No. 6) reveal a small 26 km-long strike-slip rupture at the far western end (90.5o E) with a 45-km long gap and extensional step-over between this rupture and the main Kunlun fault rupture. We hypothesize that the initial fault break occurred on this segment, with release of the normal faulting energy as a continuous rupture through the extensional step, enabling transfer of the slip to the main Kunlun fault. This process is similar to that which occurred during the 2002 Denali fault (MW 7.9) earthquake sequence except that 11 days elapsed between the October 23 (M_W 6.7) foreshock and the initial break of the Denali earthquake along a thrust fault.

Evaluating the Possibility of a joint San Andreas-Imperial Fault Rupture in the Salton Trough Region

NASA Astrophysics Data System (ADS)

Kyriakopoulos, C.; Oglesby, D. D.; Meltzner, A. J.; Rockwell, T. K.

2016-12-01

A geodynamic investigation of possible earthquakes in a given region requires both field data and numerical simulations. In particular, the investigation of past earthquakes is also a fundamental part of understanding the earthquake potential of the Salton Trough region. Geological records from paleoseismic trenches inform us of past ruptures (length, magnitude, timing), while dynamic rupture models allow us to evaluate numerically the mechanics of such earthquakes. The two most recent events (Mw 6.4 1940 and Mw 6.9 1979) on the Imperial fault (IF) both ruptured up to the northern end of the mapped fault, giving the impression that rupture doesn't propagate further north. This result is supported by small displacements, 20 cm, measured at the Dogwood site near the end of the mapped rupture in each event. However, 3D paleoseismic data from the same site corresponding to the most recent pre-1940 event (1710 CE) and 5th (1635 CE) and 6th events back revealed up to 1.5 m of slip in those events. Since we expect the surface displacement to decrease toward the termination of a rupture, we postulate that in these earlier cases the rupture propagated further north than in 1940 or 1979. Furthermore, paleoseismic data from the Coachella site (Philibosian et al., 2011) on the San Andreas fault (SAF) indicates slip events ca. 1710 CE and 1588-1662 CE. In other words, the timing of two large paleoseismic displacements on the IF cannot be distinguished from the timing of the two most recent events on the southern SAF, leaving a question: is it possible to have through-going rupture in the Salton Trough? We investigate this question through 3D dynamic finite element rupture modeling. In our work, we considered two scenarios: rupture initiated on the IF propagating northward, and rupture initiated on the SAF propagating southward. Initial results show that, in the first case, rupture propagates north of the mapped northern terminus of the IF only under certain pre-stress conditions, such as values of the seismic parameter S = 0.45 to 2.0, and tends to stop for S = 2.5. If rupture initiates in the north on the SAF, we find that it is easier for it to propagate across the entire stepover region. The results have implications for potential earthquakes in the region, with the possibility of a preferred direction of rupture propagation through the stepover.

Etiology and pathophysiology of tendon ruptures in sports.

PubMed

Kannus, P; Natri, A

1997-04-01

Of all spontaneous tendon ruptures, complete Achilles tendon tears are most closely associated with sports activities (1-3). Schönbauer (3) reported that 75% of all ruptures of the Achilles tendon are related to sports. In Plecko & Passl (2) the number was 60%. In our material of 430 cases, the number of sports-related Achilles ruptures was very similar (62%), while only 2% of ruptures of other tendons were sports-related (P < 0.001) (1). Also, the majority of Achilles reruptures occurred in sports. The ruptures occurred most often in soccer (34%), track and field (16%) and basketball (14%). The distribution of Achilles ruptures according to different sports varies considerably from country to country, according to the national sport traditions. For example, in northern and middle Europe, soccer, tennis, track and field, indoor ball games, downhill skiing, and gymnastics are the most common; and in North America, football, basketball, baseball, tennis and downhill skiing dominate the statistics (1, 2, 4). In sports, some Achilles ruptures are not spontaneous or degeneration-induced but may occur as a consequence of the remarkably high forces that are involved in the performance (2). Ruptures in the high jump or triple jump are good examples. In such cases, failure in the neuromuscular protective mechanisms due to fatigue or disturbed co-ordination can frequently be found. The spontaneous complete rupture of the supraspinatus tendon of the rotator cuff does not occur very frequently in sports. Those sports that include high-energy throwing movements, such as American and Finnish baseball, American football, rugby and discuss and javelin throwing, may, however, produce this injury. Partial tears and inflammations of the rotator cuff complex are much more frequent in throwing sports. The complete rupture of the proximal long head of the biceps brachii tendon is rare among competitive and recreational athletes. In our material, under 2% of these ruptures were associated with sports activities (5). The rupture (avulsion) of the distal tendon of the biceps muscle is rare. In sports, gymnastics, body building and weight lifting have been said to be able to produce this injury (6). In general, complete ruptures of the quadriceps tendon and the patellar tendon occur most often in older individuals. In our study, the mean age of these patients was 65 years (5). However, these injuries do also occur in younger age groups, especially in athletes. In athletes, the rupture most frequently occurs in high-power sports events, such as high jump, basketball and weight lifting, at the age of 15-30 years. A chronic-patellar apicitis (jumper's knee) may predispose rupture of the tendon (7). As is the case with the rotator cuff complex, overuse inflammation and partial tears of the quadriceps and patellar tendons are one of the most characteristic athletic injuries. Complete spontaneous ruptures of other tendons in sports are rare, although the literature does provide case studies from almost every tendon the human body possesses (8-18).

Rupture process of the 2009 L'Aquila, central Italy, earthquake, from the separate and joint inversion of Strong Motion, GPS and DInSAR data.

NASA Astrophysics Data System (ADS)

Cirella, A.; Piatanesi, A.; Tinti, E.; Chini, M.; Cocco, M.

2012-04-01

In this study, we investigate the rupture history of the April 6th 2009 (Mw 6.1) L'Aquila normal faulting earthquake by using a nonlinear inversion of strong motion, GPS and DInSAR data. We use a two-stage non-linear inversion technique. During the first stage, an algorithm based on the heat-bath simulated annealing generates an ensemble of models that efficiently sample the good data-fitting regions of parameter space. In the second stage the algorithm performs a statistical analysis of the ensemble providing us the best-fitting model, the average model, the associated standard deviation and coefficient of variation. This technique, rather than simply looking at the best model, extracts the most stable features of the earthquake rupture that are consistent with the data and gives an estimate of the variability of each model parameter. The application to the 2009 L'Aquila main-shock shows that both the separate and joint inversion solutions reveal a complex rupture process and a heterogeneous slip distribution. Slip is concentrated in two main asperities: a smaller shallow patch of slip located up-dip from the hypocenter and a second deeper and larger asperity located southeastward along strike direction. The key feature of the source process emerging from our inverted models concerns the rupture history, which is characterized by two distinct stages. The first stage begins with rupture initiation and with a modest moment release lasting nearly 0.9 seconds, which is followed by a sharp increase in slip velocity and rupture speed located 2 km up-dip from the nucleation. During this first stage the rupture front propagated up-dip from the hypocenter at relatively high (˜ 4.0 km/s), but still sub-shear, rupture velocity. The second stage starts nearly 2 seconds after nucleation and it is characterized by the along strike rupture propagation. The largest and deeper asperity fails during this stage of the rupture process. The rupture velocity is larger in the up-dip than in the along-strike direction. The up-dip and along-strike rupture propagation are separated in time and associated with a Mode II and a Mode III crack, respectively. Our results show that the 2009 L'Aquila earthquake featured a very complex rupture, with strong spatial and temporal heterogeneities suggesting a strong frictional and/or structural control of the rupture process.

[Individualized fluid-solid coupled model of intracranial aneurysms based on computed tomography angiography data].

PubMed

Wang, Fuyu; Xu, Bainan; Sun, Zhenghui; Liu, Lei; Wu, Chen; Zhang, Xiaojun

2012-10-01

To establish an individualized fluid-solid coupled model of intracranial aneurysms based on computed tomography angiography (CTA) image data. The original Dicom format image data from a patient with an intracranial aneurysm were imported into Mimics software to construct the 3D model. The fluid-solid coupled model was simulated with ANSYS and CFX software, and the sensitivity of the model was analyzed. The difference between the rigid model and fluid-solid coupled model was also compared. The fluid-solid coupled model of intracranial aneurysm was established successfully, which allowed direct simulation of the blood flow of the intracranial aneurysm and the deformation of the solid wall. The pressure field, stress field, and distribution of Von Mises stress and deformation of the aneurysm could be exported from the model. A small Young's modulus led to an obvious deformation of the vascular wall, and the walls with greater thicknesses had smaller deformations. The rigid model and the fluid-solid coupled model showed more differences in the wall shear stress and blood flow velocity than in pressure. The fluid-solid coupled model more accurately represents the actual condition of the intracranial aneurysm than the rigid model. The results of numerical simulation with the model are reliable to study the origin, growth and rupture of the aneurysms.

Rheological properties and tunable thermoplasticity of phenolic rich fraction of pyrolysis bio-oil.

PubMed

Sahaf, Amir; Laborie, Marie-Pierre G; Englund, Karl; Garcia-Perez, Manuel; McDonald, Armando G

2013-04-08

In this work we report on the preparation, characterization, and properties of a thermally treated lignin-derived, phenolic-rich fraction (PRF) of wood pyrolysis bio-oil obtained by ethyl acetate extraction. The PRF was characterized for viscoelastic and rheological behavior using dynamic mechanical analysis (DMA) and cone and plate rheology. A unique thermoplastic behavior was evidenced. Heat-treated PRFs acquire high modulus but show low temperatures of thermal flow which can be systematically manipulated through the thermal pretreatment. Loss of volatiles, changes in molecular weight, and glass transition temperature (Tg) were investigated using thermogravimetric analysis (TGA), mass spectrometry (MS), and differential scanning calorimetry (DSC), respectively. Underlying mechanisms for the thermal and rheological behavior are discussed with regard to interactions between pyrolytic lignin nanoparticles present in the system and the role of volatile materials on determining the properties of the material resembling in several aspects to colloidal suspension systems. Low thermal flow temperatures and reversible thermal effects can be attributed to association of pyrolytic lignin particles due to intermolecular interactions that are easily ruptured at higher temperatures. The thermoplastic behavior of PRF and its low Tg is of particular interest, as it gives opportunities for application of this fraction in several melt processing and adhesive technologies.

Macroscopic Source Properties from Dynamic Rupture Styles in Plastic Media

NASA Astrophysics Data System (ADS)

Gabriel, A.; Ampuero, J. P.; Dalguer, L. A.; Mai, P. M.

2011-12-01

High stress concentrations at earthquake rupture fronts may generate an inelastic off-fault response at the rupture tip, leading to increased energy absorption in the damage zone. Furthermore, the induced asymmetric plastic strain field in in-plane rupture modes may produce bimaterial interfaces that can increase radiation efficiency and reduce frictional dissipation. Off-fault inelasticity thus plays an important role for realistic predictions of near-fault ground motion. Guided by our previous studies in the 2D elastic case, we perform rupture dynamics simulations including rate-and-state friction and off-fault plasticity to investigate the effects on the rupture properties. We quantitatively analyze macroscopic source properties for different rupture styles, ranging from cracks to pulses and subshear to supershear ruptures, and their transitional mechanisms. The energy dissipation due to off-fault inelasticity modifies the conditions to obtain each rupture style and alters macroscopic source properties. We examine apparent fracture energy, rupture and healing front speed, peak slip and peak slip velocity, dynamic stress drop and size of the process and plastic zones, slip and plastic seismic moment, and their connection to ground motion. This presentation focuses on the effects of rupture style and off-fault plasticity on the resulting ground motion patterns, especially on characteristic slip velocity function signatures and resulting seismic moments. We aim at developing scaling rules for equivalent elastic models, as function of background stress and frictional parameters, that may lead to improved "pseudo-dynamic" source parameterizations for ground-motion calculation. Moreover, our simulations provide quantitative relations between off-fault energy dissipation and macroscopic source properties. These relations might provide a self-consistent theoretical framework for the study of the earthquake energy balance based on observable earthquake source parameters.

Copolymer-in-oil phantom materials for elastography.

PubMed

Oudry, J; Bastard, C; Miette, V; Willinger, R; Sandrin, L

2009-07-01

Phantoms that mimic mechanical and acoustic properties of soft biological tissues are essential to elasticity imaging investigation and to elastography device characterization. Several materials including agar/gelatin, polyvinyl alcohol and polyacrylamide gels have been used successfully in the past to produce tissue phantoms, as reported in the literature. However, it is difficult to find a phantom material with a wide range of stiffness, good stability over time and high resistance to rupture. We aim at developing and testing a new copolymer-in-oil phantom material for elastography. The phantom is composed of a mixture of copolymer, mineral oil and additives for acoustic scattering. The mechanical properties of phantoms were evaluated with a mechanical test instrument and an ultrasound-based elastography technique. The acoustic properties were investigated using a through-transmission water-substituting method. We showed that copolymer-in-oil phantoms are stable over time. Their mechanical and acoustic properties mimic those of most soft tissues: the Young's modulus ranges from 2.2-150 kPa, the attenuation coefficient from 0.4-4.0 dB.cm(-1) and the ultrasound speed from 1420-1464 m/s. Their density is equal to 0.90 +/- 0.04 g/cm3. The results suggest that copolymer-in-oil phantoms are attractive materials for elastography.

Apparent elastic modulus and hysteresis of skeletal muscle cells throughout differentiation

NASA Technical Reports Server (NTRS)

Collinsworth, Amy M.; Zhang, Sarah; Kraus, William E.; Truskey, George A.

2002-01-01

The effect of differentiation on the transverse mechanical properties of mammalian myocytes was determined by using atomic force microscopy. The apparent elastic modulus increased from 11.5 +/- 1.3 kPa for undifferentiated myoblasts to 45.3 +/- 4.0 kPa after 8 days of differentiation (P < 0.05). The relative contribution of viscosity, as determined from the normalized hysteresis area, ranged from 0.13 +/- 0.02 to 0.21 +/- 0.03 and did not change throughout differentiation. Myosin expression correlated with the apparent elastic modulus, but neither myosin nor beta-tubulin were associated with hysteresis. Microtubules did not affect mechanical properties because treatment with colchicine did not alter the apparent elastic modulus or hysteresis. Treatment with cytochalasin D or 2,3-butanedione 2-monoxime led to a significant reduction in the apparent elastic modulus but no change in hysteresis. In summary, skeletal muscle cells exhibited viscoelastic behavior that changed during differentiation, yielding an increase in the transverse elastic modulus. Major contributors to changes in the transverse elastic modulus during differentiation were actin and myosin.

[Spontaneous splenic rupture as a complication of symptom-free infections mononucleosis].

PubMed

Szokó, Márta; Matolcsy, András; Kovács, Gábor; Simon, Gábor

2007-07-22

Splenic rupture is a rare complication of infectious mononucleosis. Although it occurs only in 0.1%-0.5% of cases, splenic rupture remains the most common fatal complication of the disease. Mononucleosis related spontaneous rupture of the spleen without any other characteristic symptoms of the disease is extremely unusual, and threatens with fatal outcome due to its rare and unexpected occurrence. The authors report the case of a 16-year-old boy who needed splenectomy following a spontaneous rupture of the spleen. Serological tests proved an acute Epstein-Barr virus infection in the background but without any signs or symptoms of infectious mononucleosis. The diagnosis and treatment of this infection related to spleen ruptures are also discussed.

Non-operative management in a case of spontaneous splenic rupture in infectious mononucleosis.

PubMed

Paar, W D; Look, M P; Robertz Vaupel, G M; Kreft, B; Hirner, A; Sauerbruch, T

1995-01-01

Spontaneous splenic rupture as a complication of infectious mononucleosis was diagnosed in a 19-year-old woman. Sonographic and MRI investigations revealed subcapsular hematoma of the spleen without overt rupture. The patient was managed conservatively. Somatostatin treatment was initiated in order to reduce splanchnic blood flow. Further clinical course of the patient was favourable. Seven days after the diagnosis of splenic rupture the patient was discharged from hospital. Non-operative management should be considered in patients with subcapsular splenic rupture to avoid complications of splenectomy (e.g. post-splenectomy sepsis).

Neck curve polynomials in neck rupture model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kurniadi, Rizal; Perkasa, Yudha S.; Waris, Abdul

2012-06-06

The Neck Rupture Model is a model that explains the scission process which has smallest radius in liquid drop at certain position. Old fashion of rupture position is determined randomly so that has been called as Random Neck Rupture Model (RNRM). The neck curve polynomials have been employed in the Neck Rupture Model for calculation the fission yield of neutron induced fission reaction of {sup 280}X{sub 90} with changing of order of polynomials as well as temperature. The neck curve polynomials approximation shows the important effects in shaping of fission yield curve.

Triceps Ruptures After Fluoroquinolone Antibiotics: A Report of 2 Cases.

PubMed

Shybut, Theodore B; Puckett, Ernest R

Rupture of the triceps brachii tendon is exceedingly rare, and surgical repair is generally indicated. Fluoroquinolone antibiotics have been implicated in tendon pathology, including tendon ruptures. Triceps rupture has not been previously reported in the setting of fluoroquinolone antibiotic therapy. We present 2 cases of triceps tendon rupture after treatment with fluoroquinolones. In both cases, triceps repair was performed with good outcomes. These cases highlight a risk of fluoroquinolone-induced tendinopathy to athletes. The sports medicine team should be aware of this risk and consider it when choosing antibiotics to treat athletes.

Operating the Portable Seismic Pavement Analyzer

DTIC Science & Technology

2006-12-01

8 Thickness versus modulus...amplitude versus time waveforms....................................................................... 9 Figure 10. A thickness versus Young’s modulus plot...modulus of portland cement concrete (PCC) and asphalt concrete (AC) pavements. Additional strength parameters necessary for structural pavement

Hindlimb unloading alters ligament healing

NASA Technical Reports Server (NTRS)

Provenzano, Paolo P.; Martinez, Daniel A.; Grindeland, Richard E.; Dwyer, Kelley W.; Turner, Joanne; Vailas, Arthur C.; Vanderby, Ray Jr

2003-01-01

We investigated the hypothesis that hindlimb unloading inhibits healing in fibrous connective tissue such as ligament. Male rats were assigned to 3- and 7-wk treatment groups with three subgroups each: sham control, ambulatory healing, and hindlimb-suspended healing. Ambulatory and suspended animals underwent surgical rupture of their medial collateral ligaments, whereas sham surgeries were performed on control animals. After 3 or 7 wk, mechanical and/or morphological properties were measured in ligament, muscle, and bone. During mechanical testing, most suspended ligaments failed in the scar region, indicating the greatest impairment was to ligament and not to bone-ligament insertion. Ligament testing revealed significant reductions in maximum force, ultimate stress, elastic modulus, and low-load properties in suspended animals. In addition, femoral mineral density, femoral strength, gastrocnemius mass, and tibialis anterior mass were significantly reduced. Microscopy revealed abnormal scar formation and cell distribution in suspended ligaments with extracellular matrix discontinuities and voids between misaligned, but well-formed, collagen fiber bundles. Hence, stress levels from ambulation appear unnecessary for formation of fiber bundles yet required for collagen to form structurally competent continuous fibers. Results support our hypothesis that hindlimb unloading impairs healing of fibrous connective tissue. In addition, this study provides compelling morphological evidence explaining the altered structure-function relationship in load-deprived healing connective tissue.

Non-free gas of dipoles of non-singular screw dislocations and the shear modulus near the melting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malyshev, Cyril, E-mail: malyshev@pdmi.ras.ru

2014-12-15

The behavior of the shear modulus caused by proliferation of dipoles of non-singular screw dislocations with finite-sized core is considered. The representation of two-dimensional Coulomb gas with smoothed-out coupling is used, and the stress–stress correlation function is calculated. A convolution integral expressed in terms of the modified Bessel function K{sub 0} is derived in order to obtain the shear modulus in approximation of interacting dipoles. Implications are demonstrated for the shear modulus near the melting transition which are due to the singularityless character of the dislocations. - Highlights: • Thermodynamics of dipoles of non-singular screw dislocations is studied below themore » melting. • The renormalization of the shear modulus is obtained for interacting dipoles. • Dependence of the shear modulus on the system scales is presented near the melting.« less

The influence of low temperatures on dynamic mechanical properties of animal bone

NASA Astrophysics Data System (ADS)

Mardas, Marcin; Kubisz, Leszek; Mielcarek, Slawomir; Biskupski, Piotr

2009-01-01

Different preservation methods are currently used in bone banks, even though their effects on allograft quality are not fully understood. Freezing is one of the most popular methods of preservation in tissue banking. Yet, there is not a lot of data on dynamic mechanical properties of frozen bone. Material used in this study was femoral bones from adult bovine that were machine cut and frozen to the temperature 140°C. Both elastic modulus and loss modulus were measured at 1, 3, 5, 10, and 20 Hz in the temperature range of 30-200°C. Differences between frozen and control samples were observed. The frequency increase always led to the increase in elastic modulus values and decrease in loss modulus values. Freezing reduced the elastic modulus values of about 25% and the loss modulus values of about 45% when measured at 20°C.

Asphalt mix characterization using dynamic modulus and APA testing.

DOT National Transportation Integrated Search

2005-11-01

final report summarizes two research efforts related to asphalt mix characterization: dynamic modulus and Asphalt Pavement Analyzer testing. One phase of the research consisted of a laboratory-based evaluation of dynamic modulus of Oregon dense-grade...

Increased 18F-FDG Uptake Is Predictive of Rupture in a Novel Rat Abdominal Aortic Aneurysm Rupture Model

PubMed Central

English, Sean J.; Piert, Morand R.; Diaz, Jose A.; Gordon, David; Ghosh, Abhijit; D'Alecy, Louis G.; Whitesall, Steven E.; Sharma, Ashish K.; DeRoo, Elise P.; Watt, Tessa; Su, Gang; Henke, Peter K.; Eliason, Jonathan L.; Ailawadi, Gorav; Upchurch, Gilbert R.

2015-01-01

Objective To determine whether 18F-fluorodeoxyglucose (18F-FDG) micro–positron emission tomography (micro-PET) can predict abdominal aortic aneurysm (AAA) rupture. Background An infrarenal AAA model is needed to study inflammatory mechanisms that drive rupture. 18F-FDG PET can detect vascular inflammation in animal models and patients. Methods After exposing Sprague-Dawley rats to intra-aortic porcine pancreatic elastase (PPE) (12 U/mL), AAA rupture was induced by daily, subcutaneous, β-aminopropionitrile (BAPN, 300 mg/kg, N = 24) administration. Negative control AAA animals (N = 15) underwent daily saline subcutaneous injection after PPE exposure. BAPN-exposed animals that did not rupture served as positive controls [nonruptured AAA (NRAAA) 14d, N = 9]. Rupture was witnessed using radiotelemetry. Maximum standard uptakes for 18F-FDG micro-PET studies were determined. Aortic wall PAI-1, uPA, and tPA concentrations were determined by western blot analyses. Interleukin (IL)-1β, IL-6, IL-10, and MIP-2 were determined by Bio-Plex bead array. Neutrophil and macrophage populations per high-power field were quantified. Matrix metalloproteinase (MMP) activities were determined by zymography. Results When comparing ruptured AAA (RAAA) to NRAAA 14d animals, increased focal 18F-FDG uptakes were detected at subsequent sites of rupture (P = 0.03). PAI-1 expression was significantly less in RAAA tissue (P = 0.01), with comparable uPA and decreased tPA levels (P = 0.02). IL-1β (P = 0.04), IL-6 (P = 0.001), IL-10 (P = 0.04), and MIP-2 (P = 0.02)expression, neutrophil (P = 0.02) and macrophage presence (P = 0.002), and MMP9 (P < 0.0001) activity were increased in RAAA tissue. Conclusions With this AAA rupture model, increased prerupture 18F-FDG uptake on micro-PET imaging was associated with increased inflammation in the ruptured AAA wall. 18F-FDG PET imaging may be used to monitor inflammatory changes before AAA rupture. PMID:24651130

Mechanism for Si-Si Bond Rupture in Single Molecule Junctions.

PubMed

Li, Haixing; Kim, Nathaniel T; Su, Timothy A; Steigerwald, Michael L; Nuckolls, Colin; Darancet, Pierre; Leighton, James L; Venkataraman, Latha

2016-12-14

The stability of chemical bonds can be studied experimentally by rupturing single molecule junctions under applied voltage. Here, we compare voltage-induced bond rupture in two Si-Si backbones: one has no alternate conductive pathway whereas the other contains an additional naphthyl pathway in parallel to the Si-Si bond. We show that in contrast to the first system, the second can conduct through the naphthyl group when the Si-Si bond is ruptured using an applied voltage. We investigate this voltage induced Si-Si bond rupture by ab initio density functional theory calculations and molecular dynamics simulations that ultimately demonstrate that the excitation of molecular vibrational modes by tunneling electrons leads to homolytic Si-Si bond rupture.

Muscle shear elastic modulus is linearly related to muscle torque over the entire range of isometric contraction intensity.

PubMed

Ateş, Filiz; Hug, François; Bouillard, Killian; Jubeau, Marc; Frappart, Thomas; Couade, Mathieu; Bercoff, Jeremy; Nordez, Antoine

2015-08-01

Muscle shear elastic modulus is linearly related to muscle torque during low-level contractions (<60% of Maximal Voluntary Contraction, MVC). This measurement can therefore be used to estimate changes in individual muscle force. However, it is not known if this relationship remains valid for higher intensities. The aim of this study was to determine: (i) the relationship between muscle shear elastic modulus and muscle torque over the entire range of isometric contraction and (ii) the influence of the size of the region of interest (ROI) used to average the shear modulus value. Ten healthy males performed two incremental isometric little finger abductions. The joint torque produced by Abductor Digiti Minimi was considered as an index of muscle torque and elastic modulus. A high coefficient of determination (R(2)) (range: 0.86-0.98) indicated that the relationship between elastic modulus and torque can be accurately modeled by a linear regression over the entire range (0% to 100% of MVC). The changes in shear elastic modulus as a function of torque were highly repeatable. Lower R(2) values (0.89±0.13 for 1/16 of ROI) and significantly increased absolute errors were observed when the shear elastic modulus was averaged over smaller ROI, half, 1/4 and 1/16 of the full ROI) than the full ROI (mean size: 1.18±0.24cm(2)). It suggests that the ROI should be as large as possible for accurate measurement of muscle shear modulus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Bilateral Patellar Tendon Rupture

DTIC Science & Technology

2009-07-01

Bilateral patellar tendon rupture Military Medicine Radiology Corner, Volume 173, July, 2009...Radiology Corner Bilateral patellar tendon rupture (#37) Guarantor: 2dLt Ramon A. Riojas, USAF, MSC1 Contributors: 2dLt Ramon A. Riojas...with the abbreviated answer in the July 2009 issue. 1 The authors present a case of bilateral patellar tendon rupture in an active duty male exiting

Standardizing lightweight deflectometer modulus measurements for compaction quality assurance : research summary.

DOT National Transportation Integrated Search

2017-09-01

The mechanistic-empirical pavement design method requires the elastic resilient modulus as the key input for characterization of geomaterials. Current density-based QA procedures do not measure resilient modulus. Additionally, the density-based metho...

Resilient modulus of compacted crushed stone aggregate bases.

DOT National Transportation Integrated Search

2007-11-07

The main goal of this study was to establish a simple and efficient means of predicting the resilient modulus of different types of Kentucky crushed stone aggregate bases. To accomplish this purpose, resilient modulus of different tests were performe...

Repeatability of testing procedures for resilient modulus and fatigue : appendices.

DOT National Transportation Integrated Search

1989-04-01

The article is the appendices of "Repeatability of testing procedures for resilient modulus and fatigue". : Extensive use of diametral resilient modulus and fatigue testing is made by the Oregon State Highway Division to evaluate asphaltic concrete m...

Spontaneous tendon rupture in systemic lupus erythematosus: association with Jaccoud's arthropathy.

PubMed

Alves, E M; Macieira, J C; Borba, E; Chiuchetta, F A; Santiago, M B

2010-03-01

Tendon rupture has rarely been described in patients with systemic lupus erythematosus. From observation of three cases of Jaccoud's arthropathy with tendon rupture, and considering that this arthropathy is more related to an inflammatory process of the tendon sheath than to synovitis per se, the intention of this study was to review the cases of tendon rupture in patients with systemic lupus erythematosus, in the hope of determining the frequency of Jaccoud's arthropathy associated with this complication. Systematic review using MEDLINE, Scielo and LILACS databases (1966 to 2009) and the following keywords: systemic lupus erythematosus, tendon rupture, Jaccoud's arthropathy. Secondary references were additionally obtained. Additionally, three Brazilian systemic lupus erythematosus patients who developed tendon rupture are described. Only 40 articles obtained fulfilled the previously established criteria. They were all case reports; the number of cases reported was 52 which, together with the three cases presented herein add up to 55 cases. Forty-six patients were women aged between 19 and 71 years, with a mean age of 40.1 +/- 12.4 years, and the average duration of the disease was 10 years. The most frequently observed rupture sites were the patellar and Achilles' tendons. While almost all patients described were on various doses of corticosteroids, 16 patients concomitantly had Jaccoud's arthropathy (29%). In conclusion, the association between Jaccoud's arthropathy and tendon rupture in systemic lupus erythematosus has been underestimated. As almost one-third of the systemic lupus erythematosus patients with tendon rupture also have Jaccoud's arthropathy, this arthropathy may be recognized as risk marker for tendon rupture.

[Zwipp Percutaneous Suture of the Achilles Tendon with the Dresden Instruments].

PubMed

Chmielnicki, M; Prokop, A

2016-06-01

Rupture of the Achilles tendon is the most common rupture of a tendon in man. Acute rupture of the Achilles tendon may be treated in a variety of manners, including conservative treatment, open suture and percutaneous suture. Surgical treatment of active patients is recommended, as the risk of re-rupture is greater after non-surgical treatment. The aim of surgery is adequate treatment of Achilles tendon rupture with a low rate of complications, high comfort for patients and fast social and occupational rehabilitation. The indication for surgical treatment of Achilles tendon rupture predominantly includes ruptures in active patients, with the goal of optimal functional rehabilitation. Furthermore, the percutaneous technique protects soft tissue, with a lower rate of wound healing disorders and infection than with open surgical treatment. In our clinic we perform the percutaneous suturing technique with the Dresden instruments. The surgical technique and functional aftercare are shown in a video clip. Between 2007 and 2013, we treated 212 patients with acute Achilles tendon rupture by surgery with the Dresden instruments. There were 7 re-ruptures (3.3 %) and one case of infection within one year of surgery. Percutaneous Achilles tendon suture technique with the Dresden instruments is a safe operation that protects soft tissue. Patient satisfaction is high and the rate of complications is low. This allows rapid social and occupational rehabilitation. Georg Thieme Verlag KG Stuttgart · New York.

Multimodality Imaging-based Evaluation of Single-Lumen Silicone Breast Implants for Rupture.

PubMed

Seiler, Stephen J; Sharma, Pooja B; Hayes, Jody C; Ganti, Ramapriya; Mootz, Ann R; Eads, Emily D; Teotia, Sumeet S; Evans, W Phil

2017-01-01

Breast implants are frequently encountered on breast imaging studies, and it is essential for any radiologist interpreting these studies to be able to correctly assess implant integrity. Ruptures of silicone gel-filled implants often occur without becoming clinically obvious and are incidentally detected at imaging. Early diagnosis of implant rupture is important because surgical removal of extracapsular silicone in the breast parenchyma and lymphatics is difficult. Conversely, misdiagnosis of rupture may prompt a patient to undergo unnecessary additional surgery to remove the implant. Mammography is the most common breast imaging examination performed and can readily depict extracapsular free silicone, although it is insensitive for detection of intracapsular implant rupture. Ultrasonography (US) can be used to assess the internal structure of the implant and may provide an economical method for initial implant assessment. Common US signs of intracapsular rupture include the "keyhole" or "noose" sign, subcapsular line sign, and "stepladder" sign; extracapsular silicone has a distinctive "snowstorm" or echogenic noise appearance. Magnetic resonance (MR) imaging is the most accurate and reliable means for assessment of implant rupture and is highly sensitive for detection of both intracapsular and extracapsular rupture. MR imaging findings of intracapsular rupture include the keyhole or noose sign, subcapsular line sign, and "linguine" sign, and silicone-selective MR imaging sequences are highly sensitive to small amounts of extracapsular silicone. © RSNA, 2017.

Determination of resilient modulus values for typical plastic soils in Wisconsin.

DOT National Transportation Integrated Search

2011-09-01

"The objectives of this research are to establish a resilient modulus test results database and to develop : correlations for estimating the resilient modulus of Wisconsin fine-grained soils from basic soil properties. A : laboratory testing program ...

Mechanism for Si–Si Bond Rupture in Single Molecule Junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Haixing; Kim, Nathaniel T.; Su, Timothy A.

The stability of chemical bonds can be studied experimentally by rupturing single molecule junctions under applied voltage. Here, we compare voltage-induced bond rupture in two Si–Si backbones: one has no alternate conductive pathway whereas the other contains an additional naphthyl pathway in parallel to the Si–Si bond. We show that in contrast to the first system, the second can conduct through the naphthyl group when the Si–Si bond is ruptured using an applied voltage. We investigate this voltage induced Si–Si bond rupture by ab initio density functional theory calculations and molecular dynamics simulations that ultimately demonstrate that the excitation ofmore » molecular vibrational modes by tunneling electrons leads to homolytic Si–Si bond rupture.« less

Heart rupture predictors in Spanish myocardial infarction patients: evaluation using propensity score analysis.

PubMed

Ruiz-Bailén, Manuel; Expósito-Ruiz, Manuela; Castillo-Rivera, Ana-María; Rucabado-Aguilar, Luis; Ruiz-García, María Isabel; Ramos-Cuadra, José-Angel; Ruiz-Valverde, Andrés; Gómez-Jiménez, Javier; Benitez-Parejo, José-Luis; Cuñat de la Hoz, José; Abat, Francisco Felices; Valenzuela, Jesús Pérez

2010-05-01

The aim was to evaluate factors associated with the development of heart rupture in a Spanish registry of acute myocardial infarction (AMI) patients. This was a retrospective study of cohorts, including all patients diagnosed with AMI included in the ARIAM Spanish multicenter registry. The study period was from June 1996 to December 2005. The follow-up period was limited to the time of stay in intensive care or coronary care units. Multivariate logistic regression was used to study the factors associated with the development of heart rupture. A propensity score analysis was also performed to determine the involvement of beta blockers, ACE inhibitors, and fibrinolytics in the development of heart rupture. 16,815 AMI patients were included. Heart rupture occurred in 477 (2.8%). Heart rupture was associated with female gender, older age, the absence of previous infarct, and the administration of thrombolysis, while ACE inhibitors and beta blockers acted as protective variables. The propensity score analysis showed that fibrinolysis was a variable associated with heart rupture except in the younger subgroup and in the subgroup with less delay in administration. It was also found that beta blockers and ACE inhibitors are variables providing protection against heart rupture. Heart rupture is associated with older age, female gender, absence of previous infarct, and the administration of thrombolysis, while ACE inhibitors and beta blockers seem to prevent this complication.

Unruptured cerebral aneurysms do not shrink when they rupture: multicenter collaborative aneurysm study group.

PubMed

Rahman, Maryam; Ogilvy, Christopher S; Zipfel, Gregory J; Derdeyn, Colin P; Siddiqui, Adnan H; Bulsara, Ketan R; Kim, Louis J; Riina, Howard A; Mocco, J; Hoh, Brian L

2011-01-01

The International Study of Intracranial Aneurysms found that for patients with no previous history of subarachnoid hemorrhage, small (< 7 mm) anterior circulation and posterior circulation aneurysms had a 0% and 2.5% risk of subarachnoid hemorrhage over 5 years, respectively. To determine whether cerebral aneurysms shrink with rupture. The clinical databases of 7 sites were screened for patients with imaging of cerebral aneurysms before and after rupture. Inclusion criteria included documented subarachnoid hemorrhage by imaging or lumbar puncture and intracranial imaging before and after cerebral aneurysm rupture. The patients were evaluated for aneurysm maximal height, maximal width, neck diameter, and other measurement parameters. Only a change of ≥ 2 mm was considered a true change. Data on 13 patients who met inclusion criteria were collected. The median age was 60, and 11 of the 13 patients (84.6%) were female. Only 5 patients had posterior circulation aneurysms. None of the aneurysms had a significant decrease in size. One aneurysm decreased by 1.8 mm in maximum size after rupture (7.7%). Six aneurysms had an increase in maximum size of at least 2 mm after rupture (46.2%) with a mean increase of 3.5 mm (± 0.5 mm). Unruptured aneurysms do not shrink when they rupture. The large percentage of ruptured small aneurysms in previous studies were likely small before they ruptured.

Steady-state propagation speed of rupture fronts along one-dimensional frictional interfaces.

PubMed

Amundsen, David Skålid; Trømborg, Jørgen Kjoshagen; Thøgersen, Kjetil; Katzav, Eytan; Malthe-Sørenssen, Anders; Scheibert, Julien

2015-09-01

The rupture of dry frictional interfaces occurs through the propagation of fronts breaking the contacts at the interface. Recent experiments have shown that the velocities of these rupture fronts range from quasistatic velocities proportional to the external loading rate to velocities larger than the shear wave speed. The way system parameters influence front speed is still poorly understood. Here we study steady-state rupture propagation in a one-dimensional (1D) spring-block model of an extended frictional interface for various friction laws. With the classical Amontons-Coulomb friction law, we derive a closed-form expression for the steady-state rupture velocity as a function of the interfacial shear stress just prior to rupture. We then consider an additional shear stiffness of the interface and show that the softer the interface, the slower the rupture fronts. We provide an approximate closed form expression for this effect. We finally show that adding a bulk viscosity on the relative motion of blocks accelerates steady-state rupture fronts and we give an approximate expression for this effect. We demonstrate that the 1D results are qualitatively valid in 2D. Our results provide insights into the qualitative role of various key parameters of a frictional interface on its rupture dynamics. They will be useful to better understand the many systems in which spring-block models have proved adequate, from friction to granular matter and earthquake dynamics.

Rupture complexity and the supershear transition on rough faults

NASA Astrophysics Data System (ADS)

Bruhat, Lucile; Fang, Zijun; Dunham, Eric M.

2016-01-01

Field investigations suggest that supershear earthquakes occur on geometrically simple, smooth fault segments. In contrast, dynamic rupture simulations show how heterogeneity of stress, strength, and fault geometry can trigger supershear transitions, as well as other complex rupture styles. Here we examine the Fang and Dunham (2013) ensemble of 2-D plane strain dynamic ruptures on fractally rough faults subject to strongly rate weakening friction laws to document the effect of fault roughness and prestress on rupture behavior. Roughness gives rise to extremely diverse rupture styles, such as rupture arrests, secondary slip pulses that rerupture previously slipped fault sections, and supershear transitions. Even when the prestress is below the Burridge-Andrews threshold for supershear on planar faults with uniform stress and strength conditions, supershear transitions are observed. A statistical analysis of the rupture velocity distribution reveals that supershear transients become increasingly likely at higher stress levels and on rougher faults. We examine individual ruptures and identify recurrent patterns for the supershear transition. While some transitions occur on fault segments that are favorably oriented in the background stress field, other transitions happen at the initiation of or after propagation through an unfavorable bend. We conclude that supershear transients are indeed favored by geometric complexity. In contrast, sustained supershear propagation is most common on segments that are locally smoother than average. Because rupture style is so sensitive to both background stress and small-scale details of the fault geometry, it seems unlikely that field maps of fault traces will provide reliable deterministic predictions of supershear propagation on specific fault segments.

Radionuclide diagnosis of splenic rupture in infectious mononucleosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vezina, W.C.; Nicholson, R.L.; Cohen, P.

1984-06-01

Spontaneous splenic rupture is a rare but serious complication of infectious mononucleosis. Although radionuclide spleen imaging is a well accepted method for diagnosis of traumatic rupture, interpretation can be difficult in the setting of mononucleosis, as tears may be ill-defined and diagnosis hampered by inhomogeneous splenic uptake. Four proven cases of spontaneous rupture are presented, three of which illustrate these diagnostic problems.

Variability of Young’s modulus and Poisson’s ratio of hexagonal crystals

NASA Astrophysics Data System (ADS)

Komarova, M. A.; Gorodtsov, V. A.; Lisovenko, D. S.

2018-04-01

In this paper, the variability of elastic characteristics (Young’s modulus and Poisson’s ratio) of hexagonal crystals has been studied. Analytic expressions for Young’s modulus and Poisson’s ratio are obtained. Stationary values for these elastic characteristics are found. Young’s modulus has three stationary values, and Poisson’s ratio has eight stationary values. Numerical analysis of these elastic characteristics for hexagonal crystals is given based on the experimental data from the Landolt-Börnstein handbook. Global extrema of Young’s modulus and Poisson’s ratio for hexagonal crystals are found. Crystals are found in which the maximum values exceeds the upper limit for isotropic materials.

Permeability Variations Associated With Fault Reactivation in a Claystone Formation Investigated by Field Experiments and Numerical Simulations

NASA Astrophysics Data System (ADS)

Jeanne, Pierre; Guglielmi, Yves; Rutqvist, Jonny; Nussbaum, Christophe; Birkholzer, Jens

2018-02-01

We studied the relation between rupture and changes in permeability within a fault zone intersecting the Opalinus Clay formation at 300 m depth in the Mont Terri Underground Research Laboratory (Switzerland). A series of water injection experiments were performed in a borehole straddle interval set within the damage zone of the main fault. A three-component displacement sensor allowed an estimation of the displacement of a minor fault plane reactivated during a succession of step rate pressure tests. The experiment reveals that the fault hydromechanical (HM) behavior is different from one test to the other with varying pressure levels needed to trigger rupture and different slip behavior under similar pressure conditions. Numerical simulations were performed to better understand the reason for such different behavior and to investigate the relation between rupture nucleation, permeability change, pressure diffusion, and rupture propagation. Our main findings are as follows: (i) a rate frictional law and a rate-and-state permeability law can reproduce the first test, but it appears that the rate constitutive parameters must be pressure dependent to reproduce the complex HM behavior observed during the successive injection tests; (ii) almost similar ruptures can create or destroy the fluid diffusion pathways; (iii) a too high or too low diffusivity created by the main rupture prevents secondary rupture events from occurring whereas "intermediate" diffusivity favors the nucleation of a secondary rupture associated with the fluid diffusion. However, because rupture may in certain cases destroy permeability, this succession of ruptures may not necessarily create a continuous hydraulic pathway.

Ruptured thought: rupture as a critical attitude to nursing research.

PubMed

Beedholm, Kirsten; Lomborg, Kirsten; Frederiksen, Kirsten

2014-04-01

In this paper, we introduce the notion of ‘rupture’ from the French philosopher Michel Foucault, whose studies of discourse and governmentality have become prominent within nursing research during the last 25 years. We argue that a rupture perspective can be helpful for identifying and maintaining a critical potential within nursing research. The paper begins by introducing rupture as an inheritance from the French epistemological tradition. It then describes how rupture appears in Foucault's works, as both an overall philosophical approach and as an analytic tool in his historical studies. Two examples of analytical applications of rupture are elaborated. In the first example, rupture has inspired us to make an effort to seek alternatives to mainstream conceptions of the phenomenon under study. In the second example, inspired by Foucault's work on discontinuity, we construct a framework for historical epochs in nursing history. The paper concludes by discussing the potential of the notion of rupture as a response to the methodological concerns regarding the use of Foucault-inspired discourse analysis within nursing research. We agree with the critique of Cheek that the critical potential of discourse analysis is at risk of being undermined by research that tends to convert the approach into a fixed method.

Comparative silicone breast implant evaluation using mammography, sonography, and magnetic resonance imaging: experience with 59 implants.

PubMed

Ahn, C Y; DeBruhl, N D; Gorczyca, D P; Shaw, W W; Bassett, L W

1994-10-01

With the current controversy regarding the safety of silicone implants, the detection and evaluation of implant rupture are causing concern for both plastic surgeons and patients. Our study obtained comparative value analysis of mammography, sonography, and magnetic resonance imaging (MRI) in the detection of silicone implant rupture. Twenty-nine symptomatic patients (total of 59 silicone implants) were entered into the study. Intraoperative findings revealed 21 ruptured implants (36 percent). During physical examination, a positive "squeeze test" was highly suggestive of implant rupture. Mammograms were obtained of 51 implants (sensitivity 11 percent, specificity 89 percent). Sonography was performed on 57 implants (sensitivity 70 percent, specificity 92 percent). MRI was performed on 55 implants (sensitivity 81 percent, specificity 92 percent). Sonographically, implant rupture is demonstrated by the "stepladder sign." Double-lumen implants may appear as false-positive results for rupture on sonography. On MRI, the "linguine sign" represents disrupted fragments of a ruptured implant. The most reliable imaging modality for implant rupture detection is MRI, followed by sonogram. Mammogram is the least reliable. Our study supports the clinical indication and diagnostic value of sonogram and MRI in the evaluation of symptomatic breast implant patients.

Simultaneous uterine and urinary bladder rupture in an otherwise successful vaginal birth after cesarean delivery.

PubMed

Ho, Szu-Ying; Chang, Shuenn-Dhy; Liang, Ching-Chung

2010-12-01

Uterine rupture is the primary concern when a patient chooses a trial of labor after a cesarean section. Bladder rupture accompanied by uterine rupture should be taken into consideration if gross hematuria occurs. We report the case of a patient with uterine rupture during a trial of labor after cesarean delivery. She had a normal course of labor and no classic signs of uterine rupture. However, gross hematuria was noted after repair of the episiotomy. The patient began to complain of progressive abdominal pain, gross hematuria and oliguria. Cystoscopy revealed a direct communication between the bladder and the uterus. When opening the bladder peritoneum, rupture sites over the anterior uterus and posterior wall of the bladder were noted. Following primary repair of both wounds, a Foley catheter was left in place for 12 days. The patient had achieved a full recovery by the 2-year follow-up examination. Bladder injury and uterine rupture can occur at any time during labor. Gross hematuria immediately after delivery is the most common presentation. Cystoscopy is a good tool to identify the severity of bladder injury. Copyright © 2010 Elsevier. Published by Elsevier B.V. All rights reserved.

Base course resilient modulus for the mechanistic-empirical pavement design guide.

DOT National Transportation Integrated Search

2011-11-01

The Mechanistic-Empirical Pavement Design Guidelines (MEPDG) recommend use of modulus in lieu of structural number for base layer thickness design. Modulus is nonlinear with respect to effective confinement stress, loading strain, and moisture. For d...

Understanding the Effect of Plastic Deformation on Elastic Modulus of Metals Based on a Percolation Model with Electron Work Function

NASA Astrophysics Data System (ADS)

Li, Qingda; Hua, Guomin; Lu, Hao; Yu, Bin; Li, D. Y.

2018-05-01

The elastic modulus of materials is usually treated as a constant in engineering applications. However, plastic deformation may result in changes in the elastic modulus of metallic materials. Using brass, aluminum, and low-carbon steel as sample materials, it is demonstrated that plastic deformation decreased the elastic modulus of the materials by 10% to 20%. A percolation model incorporating the electron work function is proposed to correlate such plastic-strain-induced variations in the elastic modulus to corresponding changes in the electron work function. Efforts are made to understand the observed phenomenon on an electronic basis. The obtained experimental results are consistent with the theoretical analysis.

Fine structure of the landers fault zone: Segmentation and the rupture process

USGS Publications Warehouse

Li, Y.-G.; Vidale, J.E.; Aki, K.; Marone, C.J.; Lee, W.H.K.

1994-01-01

Observations and modeling of 3- to 6-hertz seismic shear waves trapped within the fault zone of the 1992 Landers earthquake series allow the fine structure and continuity of the zone to be evaluated. The fault, to a depth of at least 12 kilometers, is marked by a zone 100 to 200 meters wide where shear velocity is reduced by 30 to 50 percent. This zone forms a seismic waveguide that extends along the southern 30 kilometers of the Landers rupture surface and ends at the fault bend about 18 kilometers north of the main shock epicenter. Another fault plane waveguide, disconnected from the first, exists along the northern rupture surface. These observations, in conjunction with surface slip, detailed seismicity patterns, and the progression of rupture along the fault, suggest that several simple rupture planes were involved in the Landers earthquake and that the inferred rupture front hesitated or slowed at the location where the rupture jumped from one to the next plane. Reduction in rupture velocity can tentatively be attributed to fault plane complexity, and variations in moment release can be attributed to variations in available energy.

[Effects of posterior tibial slope on non-contact anterior cruciate ligament rupture and stability of anterior cruciate ligament rupture knee].

PubMed

Yue, De-bo; E, Sen; Wang, Bai-liang; Wang, Wei-guo; Guo, Wan-shou; Zhang, Qi-dong

2013-05-07

To retrospectively explore the correlation between anterior cruciate ligament (ACL)-ruptured knees, stability of ACL-rupture knee and posterior tibial slope (PTS). From January 2008 to October 2012, 150 knees with ACL rupture underwent arthroscopic surgery for ACL reconstruction. A control group was established for subjects undergoing arthroscopic surgery without ACL rupture during the same period. PTS was measured on a digitalized lateral radiograph. Lachman and mechanized pivot shift tests were performed for assessing the stability of knee. There was significant difference (P = 0.007) in PTS angle between the patients with ACL rupture (9.5 ± 2.2 degrees) and the control group (6.6 ± 1.8 degrees). Only among females, increased slope of tibial plateau had effect on the Lachman test. There was a higher positive rate of pivot shift test in patients of increased posterior slope in the ACL rupture group. Increased posterior tibial slope (>6.6) appears to contribute to non-contact ACL injuries in females. And the changes of tibial slope have no effect upon the Lachman test. However, large changes in tibial slope affect pivot shift.

Map showing surface ruptures associated with the Mammoth Lakes, California, earthquakes of May 1980

USGS Publications Warehouse

Clark, M.M.; Yount, J.C.; Vaughn, P.R.; Zepeda, R.L.

1982-01-01

This map shows surface ruptures associated with the M 6 Mammoth Lakes earthquakes of May 25-27, 1980 (Sherburne, 1980). The ruptures were mapped during USGS field investigations May 28 to June 4 and July 14-19, 1980. The map also includes some of the ruptures recorded by California Division of Mines and Geology investigators May 26-31, June 26-27, and July 7-11, 1980 (Taylor and Bryant, 1980). Because most of the surface ruptures developed in either unconsolidated pumice, alluvium, or till (and many were on slopes of scarps created by earlier faulting), wind, rain and animals quickly erased many of the ruptures. In places, the minimum detectable slip was 3-10 mm. Thus the lines on the map do not record all of the ruptures that formed at the time of the earthquake. Many of the areas were we show gaps between lines on the map probably had cracks originally. 

[Rupture of the Achilles tendon].

PubMed

Ulmar, B; Simon, S; Eschler, A; Mittlmeier, T

2014-10-01

The rupture of the Achilles tendon is the most frequent tendon rupture in humans and it is associated with increasing incidence. The main risk factor is intrinsic degeneration of the tendon. During the rupture the person feels a whiplash or dagger thrust-like pain, followed by restricted walking ability and decreased plantar flexion of the ankle. The positive Simmond/Thompson test and a palpable dent above the tendon rupture are pathognomical. Diagnostically, ultrasound of the tendon and lateral x-ray of the calcaneus (bony pull-out of the tendon insertion) are necessary. Regarding correct indication and treatment modalities, most established conservative and surgical therapies realize optimal functional results. Surgical treatment promises better primary stability and slightly earlier better functional results, but there is the potential for surgical complications. Conservative therapy is associated with higher rates of re-rupture and healing of the tendon under elongation. Therefore, therapy planning in Achilles tendon rupture should be determined based on each patient. We recommend surgical treatment in patients with higher sporting demands and in younger patients (< 50 years).

Broadband simulations for Mw 7.8 southern san andreas earthquakes: Ground motion sensitivity to rupture speed

USGS Publications Warehouse

Graves, R.W.; Aagaard, Brad T.; Hudnut, K.W.; Star, L.M.; Stewart, J.P.; Jordan, T.H.

2008-01-01

Using the high-performance computing resources of the Southern California Earthquake Center, we simulate broadband (0-10 Hz) ground motions for three Mw 7.8 rupture scenarios of the southern San Andreas fault. The scenarios incorporate a kinematic rupture description with the average rupture speed along the large slip portions of the fault set at 0.96, 0.89, and 0.84 times the local shear wave velocity. Consistent with previous simulations, a southern hypocenter efficiently channels energy into the Los Angeles region along the string of basins south of the San Gabriel Mountains. However, we find the basin ground motion levels are quite sensitive to the prescribed rupture speed, with peak ground velocities at some sites varying by over a factor of two for variations in average rupture speed of about 15%. These results have important implications for estimating seismic hazards in Southern California and emphasize the need for improved understanding of earthquake rupture processes. Copyright 2008 by the American Geophysical Union.

Paleoearthquakes at Frazier Mountain, California delimit extent and frequency of past San Andreas Fault ruptures along 1857 trace

USGS Publications Warehouse

Scharer, Katherine M.; Weldon, Ray; Streig, Ashley; Fumal, Thomas

2014-01-01

Large earthquakes are infrequent along a single fault, and therefore historic, well-characterized earthquakes exert a strong influence on fault behavior models. This is true of the 1857 Fort Tejon earthquake (estimated M7.7–7.9) on the southern San Andreas Fault (SSAF), but an outstanding question is whether the 330 km long rupture was typical. New paleoseismic data for six to seven ground-rupturing earthquakes on the Big Bend of the SSAF restrict the pattern of possible ruptures on the 1857 stretch of the fault. In conjunction with existing sites, we show that over the last ~650 years, at least 75% of the surface ruptures are shorter than the 1857 earthquake, with estimated rupture lengths of 100 to <300 km. These results suggest that the 1857 rupture was unusual, perhaps leading to the long open interval, and that a return to pre-1857 behavior would increase the rate of M7.3–M7.7 earthquakes.

Surface rupture of the 2002 Denali fault, Alaska, earthquake and comparison with other strike-slip ruptures

USGS Publications Warehouse

Haeussler, Peter J.; Schwartz, D.P.; Dawson, T.E.; Stenner, Heidi D.; Lienkaemper, J.J.; Cinti, F.; Montone, Paola; Sherrod, B.; Craw, P.

2004-01-01

On 3 November 2002, an M7.9 earthquake produced 340 km of surface rupture on the Denali and two related faults in Alaska. The rupture proceeded from west to east and began with a 40-km-long break on a previously unknown thrust fault. Estimates of surface slip on this thrust are 3-6 m. Next came the principal surface break along ???218 km of the Denali fault. Right-lateral offsets averaged around 5 m and increased eastward to a maximum of nearly 9 m. The fault also ruptured beneath the trans-Alaska oil pipeline, which withstood almost 6 m of lateral offset. Finally, slip turned southeastward onto the Totschunda fault. Right-lateral offsets are up to 3 m, and the surface rupture is about 76 km long. This three-part rupture ranks among the longest strike-slip events of the past two centuries. The earthquake is typical when compared to other large earthquakes on major intracontinental strike-slip faults. ?? 2004, Earthquake Engineering Research Institute.

Effects of ablation depth and repair time on the corneal elastic modulus after laser in situ keratomileusis.

PubMed

Wang, Xiaojun; Li, Xiaona; Chen, Weiyi; He, Rui; Gao, Zhipeng; Feng, Pengfei

2017-01-17

The biomechanical properties of the cornea should be taken into account in the refractive procedure in order to perform refractive surgery more accurately. The effects of the ablation depth and repair time on the elastic modulus of the rabbit cornea after laser in situ keratomileusis (LASIK) are still unclear. In this study, LASIK was performed on New Zealand rabbits with different ablation depth (only typical LASIK flaps were created; residual stroma bed was 50 or 30% of the whole cornea thickness respectively). The animals without any treatment were served as normal controls. The corneal thickness was measured by ultrasonic pachymetry before animals were humanly killed after 7 or 28 days post-operatively. The corneal elastic modulus was measured by uniaxial tensile testing. A mathematical procedure considering the actual geometrics of the cornea was created to analyze the corneal elastic modulus. There were no obvious differences among all groups in the elastic modulus on after 7 days post-operatively. However, after 28th days post-operatively, there was a significant increase in the elastic modulus with 50 and 30% residual stroma bed; only the elastic modulus of the cornea with 30% residual stroma bed was significantly higher than that of 7 days. Changes in elastic modulus after LASIK suggest that this biomechanical effect may correlate with the ablation depth and repair time.

Hemoperitoneum from corpus luteum rupture in patients with aplastic anemia.

PubMed

Wang, Huaquan; Guo, Lifang; Shao, Zonghong

2015-01-01

Aplastic anemia is a rare hematopoietic stem-cell disorder that results in pancytopenia and hypocellular bone marrow. Women with aplastic anemia usually are at increased risk of corpus luteum rupture due to thrombocytopenia and infection. Here we report two cases had hemoperitoneum from corpus luteum rupture in patients with aplastic anemia in our center. Case 1 involved two episodes of hemoperitoneum resulting from rupture of the corpus luteum in a 23-year-old unmarried female with severe aplastic anemia. This patient was managed conservatively with platelet and packed red cell transfusion. Case 2 involved two episodes of hemoperitoneum resulting from rupture of the corpus luteum in a 33-year-old married patient with aplastic anemia. Emergency laparoscopy revealed massive hemoperitoneum. Bilateral salpingo-oophorectomy were performed successively with platelet and packed red cell transfusion. Hemoperitoneum resulting from a ruptured corpus luteum is a life-threatening condition in patients with aplastic anemia. Prompt and appropriate evaluation of corpus luteum rupture and emergent therapy are needed.

Rupture dimensions of the 1998 Antarctic Earthquake from low-frequency waves

NASA Astrophysics Data System (ADS)

McGuire, Jeffrey J.; Zhao, Li; Jordan, Thomas H.

2000-08-01

We inverted frequency dependent phase and amplitude measurements from 1st orbit Rayleigh waves at global stations for the 1st and 2nd degree polynomial moments of the stress-glut rate tensor. The higher moments of the slip-rate distribution determine the fault plane and approximate rupture dimensions. The results show strong rupture propagation to the west with an average velocity of the instantaneous centroid of 3.6±.1 km/s. The rupture had a characteristic length of 178±46 km in the east-west direction and a characteristic duration of 48±2 s. The results are consistent with unilateral rupture on the east-west fault plane of the focal mechanism and rule out significant rupture on the north-south nodal plane.

Intrapartum uterine rupture with coincidental uterine adenomyosis in an African wild dog (Lycaon pictus).

PubMed

Newell-Fugate, Annie; Lane, Emily

2009-12-01

A 7-yr-old African wild dog (Lycaon pictus) multiparous bitch experienced severe dystocia and death one day after the onset of parturition. Necropsy revealed three placental attachments in the right uterine horn and one in the left. A full-thickness rupture of the right horn at the middle placental attachment and an autolysed fetus free in the abdomen were present. Death was attributed to hypovolemic and endotoxemic shock after uterine rupture. Myometrium adjacent to the rupture and in the left uterine horn was subdivided into irregular pseudolobules by fibrous connective tissue tracts containing small endometrial glandular acini suggestive of adenomyosis, which may have facilitated uterine rupture. This is the first reported case of dystocia-induced uterine rupture and of adenomyosis in a wild dog.

Scram recoveries---C Reactor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Constable, D.W.; Pierce, J.R.; Wood, S.A.

1962-04-26

The purpose of this report is to discuss the observations made on two equilibrium scram recovery startups (April 5 and April 16). Normally, the two startups would have little significance but unusual ruptures were experienced in the top near section of the reactor shortly after both startups, which indicates that some similarity could exist between the two. The ruptures were unusual in that the two tubes involved both had multiple ruptures. One tube contained two E{sup 2} ruptures and the other tube contained three overbore metal ruptures. The overbore tube also contained three incipient ruptures (uranium split under the can).more » The initial rise to power on both startups appeared to be normal with the flux peaking on the near side as expected. On the April 16 startup the maximum level reached was 1050 at which time a rupture in overbore tube 3062 caused on increase in pressure resulting in a high trip on the Panellit gauge. A level of 1600 was reached on the April 5 startup which was held for approximately 14 hours at which time the reactor was shut down due to rupture indications on row 29.« less

Dynamic modulus of hot mix asphalt : final report, June 2009.

DOT National Transportation Integrated Search

2009-06-01

One of the most critical parameters needed for the upcoming Mechanistic Empirical Pavement Design Guide : (MEPDG) is the dynamic modulus (E*), which will be used for flexible pavement design. The dynamic modulus : represents the stiffness of the asph...

Fan-head shear rupture mechanism as a source of off-fault tensile cracking

NASA Astrophysics Data System (ADS)

Tarasov, Boris

2016-04-01

This presentation discusses the role of a recently identified fan-head shear rupture mechanism [1] in the creation of off-fault tensile cracks observed in earthquake laboratory experiments conducted on brittle photoelastic specimens [2,3]. According to the fan-mechanism the shear rupture propagation is associated with consecutive creation of small slabs in the fracture tip which, due to rotation caused by shear displacement of the fracture interfaces, form a fan-structure representing the fracture head. The fan-head combines such unique features as: extremely low shear resistance (below the frictional strength) and self-sustaining tensile stress intensification along one side of the interface. The variation of tensile stress within the fan-head zone is like this: it increases with distance from the fracture tip up to a maximum value and then decreases. For the initial formation of the fan-head high local stresses corresponding to the fracture strength should be applied in a small area, however after completions of the fan-head it can propagate dynamically through the material at low shear stresses (even below the frictional strength). The fan-mechanism allows explaining all unique features associated with the off-fault cracking process observed in photoelastic experiments [2,3]. In these experiments spontaneous shear ruptures were nucleated in a bonded, precut, inclined and pre-stressed interface by producing a local pressure pulse in a small area. Isochromatic fringe patterns around a shear rupture propagating along bonded interface indicate the following features of the off-fault tensile crack development: tensile cracks nucleate and grow periodically along one side of the interface at a roughly constant angle (about 80 degrees) relative to the shear rupture interface; the tensile crack nucleation takes place some distance behind the rupture tip; with distance from the point of nucleation tensile cracks grow up to a certain length within the rupture head zone; behind this zone static microcracks are left in the wake of the propagating rupture. Unfortunately, the modern technology used in these experiments is not able to identify the shear rupture mechanism itself operated within the narrow rupture interface. However, a special analysis of side effects accompanying the shear rupture propagation (including the off-fault tensile cracking) allows supposing that the failure process was governed by the fan-mechanism. 1. Tarasov, B.G. 2014. Hitherto unknown shear rupture mechanism as a source of instability in intact hard rocks at highly confined compression. Tectonophysics, 621, 69-84. 2. Griffith, W.A., Rosakis, A., Pollard, D.D. and Ko, C.W., 2009. Dynamic rupture experiments elucidate tensile crack development during propagating earthquake ruptures, Geology, pp 795-798. 3. Ngo, D., Huang, Y., Rosakis, A., Griffith, W.A., Pollard D. 2012. Off-fault tensile cracks: A link between geological fault observations, lab experiments, and dynamic rupture models. Journal of Geophysical Research, vol. 117, B01307, doi: 10.1029/2011JB008577 (2012).

Rapid estimate of earthquake source duration: application to tsunami warning.

NASA Astrophysics Data System (ADS)

Reymond, Dominique; Jamelot, Anthony; Hyvernaud, Olivier

2016-04-01

We present a method for estimating the source duration of the fault rupture, based on the high-frequency envelop of teleseismic P-Waves, inspired from the original work of (Ni et al., 2005). The main interest of the knowledge of this seismic parameter is to detect abnormal low velocity ruptures that are the characteristic of the so called 'tsunami-earthquake' (Kanamori, 1972). The validation of the results of source duration estimated by this method are compared with two other independent methods : the estimated duration obtained by the Wphase inversion (Kanamori and Rivera, 2008, Duputel et al., 2012) and the duration calculated by the SCARDEC process that determines the source time function (M. Vallée et al., 2011). The estimated source duration is also confronted to the slowness discriminant defined by Newman and Okal, 1998), that is calculated routinely for all earthquakes detected by our tsunami warning process (named PDFM2, Preliminary Determination of Focal Mechanism, (Clément and Reymond, 2014)). Concerning the point of view of operational tsunami warning, the numerical simulations of tsunami are deeply dependent on the source estimation: better is the source estimation, better will be the tsunami forecast. The source duration is not directly injected in the numerical simulations of tsunami, because the cinematic of the source is presently totally ignored (Jamelot and Reymond, 2015). But in the case of a tsunami-earthquake that occurs in the shallower part of the subduction zone, we have to consider a source in a medium of low rigidity modulus; consequently, for a given seismic moment, the source dimensions will be decreased while the slip distribution increased, like a 'compact' source (Okal, Hébert, 2007). Inversely, a rapid 'snappy' earthquake that has a poor tsunami excitation power, will be characterized by higher rigidity modulus, and will produce weaker displacement and lesser source dimensions than 'normal' earthquake. References: CLément, J. and Reymond, D. (2014). New Tsunami Forecast Tools for the French Polynesia Tsunami Warning System. Pure Appl. Geophys, 171. DUPUTEL, Z., RIVERA, L., KANAMORI, H. and HAYES, G. (2012). Wphase source inversion for moderate to large earthquakes. Geophys. J. Intl.189, 1125-1147. Kanamori, H. (1972). Mechanism of tsunami earthquakes. Phys. Earth Planet. Inter. 6, 246-259. Kanamori, H. and Rivera, L. (2008). Source inversion of W phase : speeding up seismic tsunami warning. Geophys. J. Intl. 175, 222-238. Newman, A. and Okal, E. (1998). Teleseismic estimates of radiated seismic energy : The E=M0 discriminant for tsunami earthquakes. J. Geophys. Res. 103, 26885-26898. Ni, S., H. Kanamori, and D. Helmberger (2005), Energy radiation from the Sumatra earthquake, Nature, 434, 582. Okal, E.A., and H. Hébert (2007), Far-field modeling of the 1946 Aleutian tsunami, Geophys. J. Intl., 169, 1229-1238. Vallée, M., J. Charléty, A.M.G. Ferreira, B. Delouis, and J. Vergoz, SCARDEC : a new technique for the rapid determination of seismic moment magnitude, focal mechanism and source time functions for large earthquakes using body wave deconvolution, Geophys. J. Int., 184, 338-358, 2011.

Relation between energy radiation ratio and rupture speed in numerically simulated earthquakes

NASA Astrophysics Data System (ADS)

Noda, H.; Lapusta, N.; Kanamori, H.

2011-12-01

One of the prominent questions in seismology is energy partitioning during an earthquake. Venkataraman and Kanamori [2004] discussed radiation ratio η_R, the ratio of radiated energy E_R to partial strain energy change ΔW_0 which is the total released strain energy minus the energy that would have been dissipated if a fault had slipped at the final stress. They found positive correlation between η_R and rupture speed in large earthquakes, and compared these data with theoretical estimates from simplified models. The relation between η_R and rupture speed is of great interest since both quantities can be estimated independently although there are large uncertainties. We conduct numerical simulations of dynamic ruptures and study the obtained energy partitioning (and η_R) and averaged rupture speeds V_r. So far, we have considered problems based on TPV103 from the SCEC/USGS Spontaneous Rupture Code Verification Project [Harris et al., 2009, http://scecdata.usc.edu/cvws/], which is a 3-D problem with the possibility of remarkable rate weakening at coseismic slip rates caused by flash heating of microscopic asperities [Rice, 1999]. We study the effect of background shear stress level τ_b and the manner in which rupture is arrested, either in rate-strengthening or unbreakable areas of the fault. Note that rupture speed at each fault point is defined when the rupture is still in progress, while η_R is defined after all dynamic processes such as propagation of a rupture front, healing fronts, and seismic waves have been completed. Those complexities may cause a difference from the theoretical estimates based on simple models, an issue we explore in this study. Overall, our simulations produce the relation between η_R and V_r broadly consistent with the study of Venkataraman and Kanamori (2004) for natural earthquakes and the corresponding theoretical estimates. The model by Mott [1948] agrees best with the cases studied so far, although it is not rigorously correct [Freund, 1990]. For example, a case which is similar to TPV103 except in the nucleation procedure yields a pulse-like rupture with a spatially averaged rupture speed V_r = 0.59 c_s and η_R = 0.32, while the theoretical estimates [Fossum and Freund, 1975 for mode II and Kostrov, 1966; Ehselby, 1969 for mode III] predict η_R of about 0.5 for this rupture speed. This difference is not significant compared with the large observational error. As τ_b increases, V_r increases monotonically, while η_R exhibits more complex behavior: it increases with τ_b for pulse-like ruptures, decreases by about 0.1 at the transition to crack-like ruptures, and then increases again. Frictional dissipation is significant when a rupture front reaches a rate-strengthening region. If the barrier is changed to an unbreakable region, η_R decreases and V_r/c_s increases at most by 0.3 and 0.1, respectively. Although sharper arrest of rupture causes larger E_R per seismic moment due to the stopping phases, ΔW_0 per seismic moment increases more remarkably due to large wavenumber components in final slip distribution.

Patients with an Achilles tendon re-rupture have long-term functional deficits in function and worse patient-reported outcome than primary ruptures.

PubMed

Westin, Olof; Nilsson Helander, Katarina; Grävare Silbernagel, Karin; Samuelsson, Kristian; Brorsson, Annelie; Karlsson, Jón

2018-04-24

The aim of this study was to perform a long-term follow-up of patients treated for an Achilles tendon re-rupture, using established outcome measurements for tendon structure, lower extremity function and symptoms, and to compare the results with those for the uninjured side. A secondary aim was to compare the outcome with that of patients treated for primary ruptures. The hypotheses were that patients with a re-rupture recover well, and have similar long-term outcome as primary ruptures. Twenty patients (4 females) with a mean (SD) age of 44 (10.9) years, ranging from 24 to 64, were included. The patients were identified by reviewing the medical records of all Achilles tendon ruptures at Sahlgrenska University Hospital and Kungsbacka Hospital, Sweden, between 2006 and 2016. All patients received standardised surgical treatment and rehabilitation. The mean (SD) follow-up was 51 (38.1) months. A test battery of validated clinical and functional tests, patient-reported outcome measurements and measurements of tendon elongation were performed at the final follow-up. This cohort was then compared with the 2-year follow-up results from a previous randomised controlled trial of patients treated for primary Achilles tendon rupture. There were deficits on the injured side compared with the healthy side in terms of heel-rise height (11.9 versus 12.5 cm, p = 0.008), repetitions (28.5 versus 31.7, p = 0.004) and drop-jump height (13.2 versus 15.1 cm, p = 0.04).  There was a significant difference in calf circumference (37.1 versus 38.4 cm, p =< 0.001) and ankle dorsiflexion on the injured side compared with the healthy side (35.3° versus 40.8°, p = 0.003). However, no significant differences were found in terms of tendon length 22.5 (2.5) cm on the injured side and 21.8 (2.8) cm on the healthy side. Compared with primary ruptures, the re-rupture cohort obtained significantly worse results for the Achilles tendon total rupture score, with a mean of 78 (21.2) versus 89.5 (14.6) points, (p = 0.007). The re-ruptures showed a higher mean LSI heel-rise height, 94.7% (9.3%) versus 83.5% (11.7%) (p = < 0.0001), and superior mean LSI eccentric-concentic power, 110.4% (49.8%) versus 79.3% (21%) (p = 0.001), than the primary ruptures. The results of this study indicate that patients with an Achilles tendon re-rupture had continued symptoms and functional deficits on the injured side, after a long-term follow-up. Patients with an Achilles tendon re-rupture had worse patient-reported outcomes but similar or superior functional results compared with patients with primary ruptures. Case series, Level IV.

Using Multi-scale Dynamic Rupture Models to Improve Ground Motion Estimates: ALCF-2 Early Science Program Technical Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ely, Geoffrey P.

2013-10-31

This project uses dynamic rupture simulations to investigate high-frequency seismic energy generation. The relevant phenomena (frictional breakdown, shear heating, effective normal-stress fluctuations, material damage, etc.) controlling rupture are strongly interacting and span many orders of magnitude in spatial scale, requiring highresolution simulations that couple disparate physical processes (e.g., elastodynamics, thermal weakening, pore-fluid transport, and heat conduction). Compounding the computational challenge, we know that natural faults are not planar, but instead have roughness that can be approximated by power laws potentially leading to large, multiscale fluctuations in normal stress. The capacity to perform 3D rupture simulations that couple these processes willmore » provide guidance for constructing appropriate source models for high-frequency ground motion simulations. The improved rupture models from our multi-scale dynamic rupture simulations will be used to conduct physicsbased (3D waveform modeling-based) probabilistic seismic hazard analysis (PSHA) for California. These calculation will provide numerous important seismic hazard results, including a state-wide extended earthquake rupture forecast with rupture variations for all significant events, a synthetic seismogram catalog for thousands of scenario events and more than 5000 physics-based seismic hazard curves for California.« less

Developing the elastic modulus measurement of asphalt concrete using the compressive strength test

NASA Astrophysics Data System (ADS)

Setiawan, Arief; Suparma, Latif Budi; Mulyono, Agus Taufik

2017-11-01

Elastic modulus is a fundamental property of an asphalt mixture. An analytical method of the elastic modulus is needed to determine the thickness of flexible pavement. It has a role as one of the input values on a stress-strain analysis in the finite element method. The aim of this study was to develop the measurement of the elastic modulus by using compressive strength testing. This research used a set of specimen mold tool and Delta Dimensi software to record strain changes occurring in the proving ring of compression machine and the specimens. The elastic modulus of the five types of aggregate gradation and 2 types of asphalt were measured at optimum asphalt content. Asphalt Cement 60/70 and Elastomer Modified Asphalt (EMA) were used as a binder. Manufacturing success indicators of the specimens used void-in-the-mix (VIM) 3-5 % criteria. The success rate of the specimen manufacturing was more than 76%. Thus, the procedure and the compressive strength test equipment could be used for the measurement of the elastic modulus. The aggregate gradation and asphalt types significantly affected the elastic modulus of the asphalt concrete.

Measurement error of Young’s modulus considering the gravity and thermal expansion of thin specimens for in situ tensile testing

NASA Astrophysics Data System (ADS)

Ma, Zhichao; Zhao, Hongwei; Ren, Luquan

2016-06-01

Most miniature in situ tensile devices compatible with scanning/transmission electron microscopes or optical microscopes adopt a horizontal layout. In order to analyze and calculate the measurement error of the tensile Young’s modulus, the effects of gravity and temperature changes, which would respectively lead to and intensify the bending deformation of thin specimens, are considered as influencing factors. On the basis of a decomposition method of static indeterminacy, equations of simplified deflection curves are obtained and, accordingly, the actual gage length is confirmed. By comparing the effects of uniaxial tensile load on the change of the deflection curve with gravity, the relation between the actual and directly measured tensile Young’s modulus is obtained. Furthermore, the quantitative effects of ideal gage length l o, temperature change ΔT and the density ρ of the specimen on the modulus difference and modulus ratio are calculated. Specimens with larger l o and ρ present more obvious measurement errors for Young’s modulus, but the effect of ΔT is not significant. The calculation method of Young’s modulus is particularly suitable for thin specimens.

Rupture Propagation Imaging of Fluid Induced Events at the Basel EGS Project

NASA Astrophysics Data System (ADS)

Folesky, Jonas; Kummerow, Jörn; Shapiro, Serge A.

2014-05-01

The analysis of rupture properties using rupture propagation imaging techniques is a fast developing field of research in global seismology. Usually rupture fronts of large to megathrust earthquakes are subject of recent studies, like e.g. the 2004 Sumatra-Andaman earthquake or the 2011 Tohoku, Japan earthquake. The back projection technique is the most prominent technique in this field. Here the seismograms recorded at an array or at a seismic network are back shifted to a grid of possible source locations via a special stacking procedure. This can provide information on the energy release and energy distribution of the rupture which then can be used to find estimates of event properties like location, rupture direction, rupture speed or length. The procedure is fast and direct and it only relies on a reasonable velocity model. Thus it is a good way to rapidly estimate the rupture properties and it can be used to confirm independently achieved event information. We adopted the back projection technique and put it in a microseismic context. We demonstrated its usage for multiple synthetic ruptures within a reservoir model of microseismic scale in earlier works. Our motivation hereby is the occurrence of relatively large, induced seismic events at a number of stimulated geothermal reservoirs or waste disposal sites, having magnitudes ML ≥ 3.4 and yielding rupture lengths of several hundred meters. We use the configuration of the seismic network and reservoir properties of the Basel Geothermal Site to build a synthetic model of a rupture by modeling the wave field of multiple spatio-temporal separated single sources using Finite-Difference modeling. The focus of this work is the application of the Back Projection technique and the demonstration of its feasibility to retrieve the rupture properties of real fluid induced events. We take four microseismic events with magnitudes from ML 3.1 to 3.4 and reconstruct source parameters like location, orientation and length. By comparison with our synthetic results as well as independent localization studies and source mechanism studies in this area we can show, that the obtained results are reasonable and that the application of back projection imaging is not only possible for microseismic datasets of respective quality, but that it provides important additional insights in the rupture process.

Crystal plastic earthquakes in dolostones: from slow to fast ruptures.

NASA Astrophysics Data System (ADS)

Passelegue, F. X.; Aubry, J.; Nicolas, A.; Fondriest, M.; Schubnel, A.; Di Toro, G.

2017-12-01

Dolostone is the most dominant lithology of the seismogenic upper crust around the Mediterranean Sea. Understanding the internal mechanisms controlling fault friction is crucial for understanding seismicity along active faults. Displacement in such fault zones is frequently highlighted by highly reflective (mirror-like) slip surfaces, created by thin films of nanogranular fault rock. Using saw-cut dolostone samples coming from natural fault zones, we conducted stick-slip experiments under triaxial loading conditions at 30, 60 and 90 MPa confining pressure and temperature ranging from 30 to 100 degrees C. At 30 and 65 degrees C, only slow rupture was observed and the experimental fault exhibits frictional behaviour, i.e. a dependence of normal stress on peak shear stress. At 65 degrees C, a strengthening behaviour is observed after the main rupture, leading to a succession of slow rupture. At 100 degrees C, the macroscopic behaviour of the fault becomes ductile, and no dependence of pressure on the peak shear stress is observed. In addition, the increase of the confining pressure up to 60 and 90 MPa allow the transition from slow to fast rupture, highlighted by the records of acoustic activity and by dynamic stress drop occurring in a few tens of microseconds. Using strain gages located along the fault surface and acoustic transducers, we were able to measure the rupture velocities during slow and fast rupture. Slow ruptures propagated around 0.1 m/s, in agreement with natural observations. Fast ruptures propagated up to supershear velocities, i.e. faster than the shear wave speed (>3500 m/s). A complete study of the microstructures was realized before and after ruptures. Slow ruptures lead to the production of mirror-like surface driven by the production of nanograins due to dislocation processes. Fast ruptures induce the production of amorphous material along the fault surface, which may come from decarbonation and melting processes. We demonstrate that the transition from slow to fast instabilities is observed due to an increase of the fault stiffness with increasing both temperature and confining pressure. This increase in the stiffness leads to an increase of the slip velocity during the main instability, which allow flash weakening processes and fast propagation of the seismic rupture.

Determination of elastic modulus of ceramics using ultrasonic testing

NASA Astrophysics Data System (ADS)

Sasmita, Firmansyah; Wibisono, Gatot; Judawisastra, Hermawan; Priambodo, Toni Agung

2018-04-01

Elastic modulus is important material property on structural ceramics application. However, bending test as a common method for determining this property require particular specimen preparation. Furthermore, elastic modulus of ceramics could vary because it depends on porosity content. For structural ceramics industry, such as ceramic tiles, this property is very important. This drives the development of new method to improve effectivity or verification method as well. In this research, ultrasonic testing was conducted to determine elastic modulus of soda lime glass and ceramic tiles. The experiment parameter was frequency of probe (1, 2, 4 MHz). Characterization of density and porosity were also done for analysis. Results from ultrasonic testing were compared with elastic modulus resulted from bending test. Elastic modulus of soda-lime glass based on ultrasonic testing showed excellent result with error 2.69% for 2 MHz probe relative to bending test result. Testing on red and white ceramic tiles were still contained error up to 41% and 158%, respectively. The results for red ceramic tile showed trend that 1 MHz probe gave better accuracy in determining elastic modulus. However, testing on white ceramic tile showed different trend. It was due to the presence of porosity and near field effect.

The association between lunar phase and intracranial aneurysm rupture: Myth or reality? Own data and systematic review.

PubMed

Bunevicius, Adomas; Gendvilaite, Agne; Deltuva, Vytenis Pranas; Tamasauskas, Arimantas

2017-05-19

It is a common belief in medical community that lunar phases have an impact on human health. A growing body of evidence indicates that lunar phases can predict the risk to develop acute neurological and vascular disorders. The goal of present report was to present our institution data and to perform systematic review of studies examining the association of intracranial aneurysm rupture with moon phases. We identified all patients admitted to our department for ruptured intracranial aneurysms in a period between November, 2011 and December, 2014. Patients with a known aneurysm rupture date were included. Lunar phases were determined by dividing lunar month (29.5 days) into eight equal parts, i.e., new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter and waning crescent. A systematic literature review was undertaken to identify studies that evaluated the association of lunar phases with the incident of intracranial aneurysm rupture. One hundred and eighty-six patients (62 men and 124 women, median age 56 years) were admitted to our department for treatment of ruptured intracranial aneurysms. The rate of intracranial aneurysm rupture was equally distributed across all phases of the lunar cycle (X 2 [7; 185] = 12.280, p = 0.092). We identified three studies that evaluated the association between incident intracranial aneurysm rupture and lunar phases with a total of 1483 patients. One study from Lebanon found that the incidence rate of intracranial aneurysm rupture was statistically significantly greater during the new moon phase (25% cases), relative to the other seven lunar phases (p < 0.001). Two subsequent studies from Austria and Germany in larger patient samples (n = 717 and n = 655, respectively) did not find an association between lunar phases and intracranial aneurysm rupture (p-values of 0.84 and 0.97, respectively). When analyzing all four studies together, we did not find an association between lunar phases and incidence of intracranial aneurysm rupture (X 2 [1668; 7] = 2.080, p = 0.955). Moon phases are not associated with incidence of intracranial aneurysm rupture. Studies investigating the association of intracranial aneurysm rupture with lunar illumination defined using more sensitive approaches are encouraged.

The Effects of Fault Bends on Rupture Propagation: A Parameter Study

NASA Astrophysics Data System (ADS)

Lozos, J. C.; Oglesby, D. D.; Duan, B.; Wesnousky, S. G.

2008-12-01

Segmented faults with stepovers are ubiquitous, and occur at a variety of scales, ranging from small stepovers on the San Jacinto Fault, to the large-scale stepover on of the San Andreas Fault between Tejon Pass and San Gorgonio Pass. Because this type of fault geometry is so prevalent, understanding how rupture propagates through such systems is important for evaluating seismic hazard at different points along these faults. In the present study, we systematically investigate how far rupture will propagate through a fault with a linked (i.e., continuous fault) stepover, based on the length of the linking fault segment and the angle that connects the linking segment to adjacent segments. We conducted dynamic models of such systems using a two-dimensional finite element code (Duan and Oglesby 2007). The fault system in our models consists of three segments: two parallel 10km-long faults linked at a specified angle by a linking segment of between 500 m and 5 km. This geometry was run both as a extensional system and a compressional system. We observed several distinct rupture behaviors, with systematic differences between compressional and extensional cases. Both shear directions rupture straight through the stepover for very shallow stepover angles. In compressional systems with steeper angles, rupture may jump ahead from the stepover segment onto the far segment; whether or not rupture on this segment reaches critical patch size and slips fully is also a function of angle and stepover length. In some compressional cases, if the angle is steep enough and the stepover short enough, rupture may jump over the step entirely and propagate down the far segment without touching the linking segment. In extensional systems, rupture jumps from the nucleating segment onto the linking segment even at shallow angles, but at steeper angles, rupture propagates through without jumping. It is easier to propagate through a wider range of angles in extensional cases. In both extensional and compressional cases, for each stepover length there exists a maximum angle through which rupture can fully propagate; this maximum angle decreases asymptotically to a minimum value as the stepover length increases. We also found that a wave associated with a stopping phase coming from the far end of the fault may restart rupture and induce full propagation after a significant delay in some cases where the initial rupture terminated.

PIP silicone breast implants: rupture rates based on the explantation of 676 implants in a single surgeon series.

PubMed

Quaba, Omar; Quaba, Awf

2013-09-01

To determine the true rupture rates of PIP implants from a large single surgeon cohort and to assess whether rupture rates varied depending on time of implant insertion. In addition, the efficacy of ultra sound scanning (USS) in determining rupture is examined. Predominantly prospectively based analysis of patient records, investigations and surgical findings. 338 patients (676 implants) were included in the study and they all had removal of their implants. The senior author operated on all patients at some stage of their treatment. 160 patients were imaged pre-operatively with USS. Patients had implants inserted between 1999 and 2007 for cosmetic breast augmentation. A total of 144 ruptured implants were removed from 119 patients, giving a rupture rate of 35.2% per patient and 21.3% per implant over a mean implantation period of 7.8 years. A statistical difference (P < 0.001) in rupture rates between implants inserted prior to 2003 and those inserted from 2003 was demonstrated, with higher failure rates in the latter group. There was a significant difference in rupture rates depending on pocket placement of the implants. The sensitivity and specificity of USS at detecting rupture was 90.6% and 98.3% respectively. A proportion of patients (29.4%) demonstrated loco-regional spread of silicone to the axilla on scanning. Our paper has confirmed high rates of PIP implant failure in the largest published series to date. The significant difference in rupture rates between implants inserted prior to 2003 and those after this time supports the view that industrial silicone was used in the devices after 2003. Implants are more likely to rupture if inserted in the sub muscular plane compared to the sub glandular plane. USS is highly effective at detecting rupture in PIP implants and loco-regional spread is high compared to other devices. We believe this paper provides hard data enabling more informed decision making for patients, clinicians and providers in what remains an active issue affecting thousands of women. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Ab-initio study of electronic structure and elastic properties of ZrC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mund, H. S., E-mail: hmoond@gmail.com; Ahuja, B. L.

2016-05-23

The electronic and elastic properties of ZrC have been investigated using the linear combination of atomic orbitals method within the framework of density functional theory. Different exchange-correlation functionals are taken into account within generalized gradient approximation. We have computed energy bands, density of states, elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, lattice parameters and pressure derivative of the bulk modulus by calculating ground state energy of the rock salt structure type ZrC.

Evaluation of Variability in Resilient Modulus Test Results (ASTM D4123)

DOT National Transportation Integrated Search

1989-10-01

Samples of asphalt mixture were evaluated in the laboratory under various conditions to evaluate the repeatability of the resilient modulus test and to evaluate the effect of stress on the measured resilient modulus. Some of the samples were prepared...

CyberShake: A Physics-Based Seismic Hazard Model for Southern California

NASA Astrophysics Data System (ADS)

Graves, Robert; Jordan, Thomas H.; Callaghan, Scott; Deelman, Ewa; Field, Edward; Juve, Gideon; Kesselman, Carl; Maechling, Philip; Mehta, Gaurang; Milner, Kevin; Okaya, David; Small, Patrick; Vahi, Karan

2011-03-01

CyberShake, as part of the Southern California Earthquake Center's (SCEC) Community Modeling Environment, is developing a methodology that explicitly incorporates deterministic source and wave propagation effects within seismic hazard calculations through the use of physics-based 3D ground motion simulations. To calculate a waveform-based seismic hazard estimate for a site of interest, we begin with Uniform California Earthquake Rupture Forecast, Version 2.0 (UCERF2.0) and identify all ruptures within 200 km of the site of interest. We convert the UCERF2.0 rupture definition into multiple rupture variations with differing hypocenter locations and slip distributions, resulting in about 415,000 rupture variations per site. Strain Green Tensors are calculated for the site of interest using the SCEC Community Velocity Model, Version 4 (CVM4), and then, using reciprocity, we calculate synthetic seismograms for each rupture variation. Peak intensity measures are then extracted from these synthetics and combined with the original rupture probabilities to produce probabilistic seismic hazard curves for the site. Being explicitly site-based, CyberShake directly samples the ground motion variability at that site over many earthquake cycles (i.e., rupture scenarios) and alleviates the need for the ergodic assumption that is implicitly included in traditional empirically based calculations. Thus far, we have simulated ruptures at over 200 sites in the Los Angeles region for ground shaking periods of 2 s and longer, providing the basis for the first generation CyberShake hazard maps. Our results indicate that the combination of rupture directivity and basin response effects can lead to an increase in the hazard level for some sites, relative to that given by a conventional Ground Motion Prediction Equation (GMPE). Additionally, and perhaps more importantly, we find that the physics-based hazard results are much more sensitive to the assumed magnitude-area relations and magnitude uncertainty estimates used in the definition of the ruptures than is found in the traditional GMPE approach. This reinforces the need for continued development of a better understanding of earthquake source characterization and the constitutive relations that govern the earthquake rupture process.

CyberShake: A Physics-Based Seismic Hazard Model for Southern California

USGS Publications Warehouse

Graves, R.; Jordan, T.H.; Callaghan, S.; Deelman, E.; Field, E.; Juve, G.; Kesselman, C.; Maechling, P.; Mehta, G.; Milner, K.; Okaya, D.; Small, P.; Vahi, K.

2011-01-01

CyberShake, as part of the Southern California Earthquake Center's (SCEC) Community Modeling Environment, is developing a methodology that explicitly incorporates deterministic source and wave propagation effects within seismic hazard calculations through the use of physics-based 3D ground motion simulations. To calculate a waveform-based seismic hazard estimate for a site of interest, we begin with Uniform California Earthquake Rupture Forecast, Version 2.0 (UCERF2.0) and identify all ruptures within 200 km of the site of interest. We convert the UCERF2.0 rupture definition into multiple rupture variations with differing hypocenter locations and slip distributions, resulting in about 415,000 rupture variations per site. Strain Green Tensors are calculated for the site of interest using the SCEC Community Velocity Model, Version 4 (CVM4), and then, using reciprocity, we calculate synthetic seismograms for each rupture variation. Peak intensity measures are then extracted from these synthetics and combined with the original rupture probabilities to produce probabilistic seismic hazard curves for the site. Being explicitly site-based, CyberShake directly samples the ground motion variability at that site over many earthquake cycles (i. e., rupture scenarios) and alleviates the need for the ergodic assumption that is implicitly included in traditional empirically based calculations. Thus far, we have simulated ruptures at over 200 sites in the Los Angeles region for ground shaking periods of 2 s and longer, providing the basis for the first generation CyberShake hazard maps. Our results indicate that the combination of rupture directivity and basin response effects can lead to an increase in the hazard level for some sites, relative to that given by a conventional Ground Motion Prediction Equation (GMPE). Additionally, and perhaps more importantly, we find that the physics-based hazard results are much more sensitive to the assumed magnitude-area relations and magnitude uncertainty estimates used in the definition of the ruptures than is found in the traditional GMPE approach. This reinforces the need for continued development of a better understanding of earthquake source characterization and the constitutive relations that govern the earthquake rupture process. ?? 2010 Springer Basel AG.

[Heart rupture in acute myocardial infarction: multicenter observational study of the coronary unit of Piedmont].

PubMed

Pron, Paolo Giay; Angelino, Paolo; Varbella, Ferdinando; Bongioanni, Sergio; Masi, Andrea Sibona; Iazzolino, Ernesto; Bonfiglio, Giovanna; Brusin, Maria Cristina Rosa; Mainardi, Loredana; Nicastro, Cristina; Bouslenko, Zoe; Conte, Maria Rosa

2002-02-01

The aim of this study was to prospectively evaluate the incidence of cardiac rupture during myocardial infarction (MI) as well as the predictive value of the main cardiac rupture risk factors. The study was carried out in 17 coronary care units (CCU) between January and December 1999 in the Piedmont region (Italy). The incidence of cardiac rupture was 1.4% of the total number of MI (n = 3041). Data from 13 out of 17 CCU showed the following causes of death during MI: 66% heart failure, 16% cardiac rupture, 7% arrhythmias, 11% others. Twenty-seven percent out of 44 cardiac ruptures had prior angina, 9% prior MI; 24% of patients were diabetic; 38% had anterior wall MI; 62% infero-postero-lateral MI; 86% showed ST-segment elevation, and 79.5% developed Q waves. Thrombolysis was administered in 39% of cases. Forty-three percent cardiac ruptures occurred within 24 hours. Electromechanical dissociation was present in 73% of cases, syncope and hypotension in 43%, bradycardia in 30%. An echocardiogram was performed in 89% of cases in the suspicion of cardiac rupture but only 45% showed severe pericardial effusion. One patient was referred to surgery but he died in the postoperative period. Autoptical diagnosis was made in 32% of cases. All patients died. The analysis of some qualitative variables (gender, thrombolysis, MI localization, ST-segment/non-ST-segment elevation) in 8 out of 17 CCU, between the cardiac rupture group (n = 22) and the MI group (n = 1330) showed a significant result only for the female gender. Cardiac rupture is the second cause of death during MI after heart failure; there is a higher incidence of cardiac rupture in infero-postero-lateral MI, after the first 24 hours particularly in the female gender; there is a low global incidence (1.4%).

The International Network of Obstetric Survey Systems study of uterine rupture: a descriptive multi-country population-based study.

PubMed

Vandenberghe, G; Bloemenkamp, K; Berlage, S; Colmorn, L; Deneux-Tharaux, C; Gissler, M; Knight, M; Langhoff-Roos, J; Lindqvist, P G; Oberaigner, W; Van Roosmalen, J; Zwart, J; Roelens, K

2018-05-04

International comparison of complete uterine rupture. Descriptive multi-country population-based study. International. International Network of Obstetric Survey Systems (INOSS). We merged individual data, collected prospectively in nine population-based studies, of women with complete uterine rupture, defined as complete disruption of the uterine muscle and the uterine serosa, regardless of symptoms and rupture of fetal membranes. Prevalence of complete uterine rupture, regional variation and correlation with rates of caesarean section (CS) and trial of labour after CS (TOLAC). Severe maternal and perinatal morbidity and mortality. We identified 864 complete uterine ruptures in 2 625 017 deliveries. Overall prevalence was 3.3 (95% CI 3.1-3.5) per 10 000 deliveries, 22 (95% CI 21-24) in women with and 0.6 (95% CI 0.5-0.7) in women without previous CS. Prevalence in women with previous CS was negatively correlated with previous CS rate (ρ = -0.917) and positively correlated with TOLAC rate of the background population (ρ = 0.600). Uterine rupture resulted in peripartum hysterectomy in 87 of 864 women (10%, 95% CI 8-12%) and in a perinatal death in 116 of 874 infants (13.3%, 95% CI 11.2-15.7) whose mother had uterine rupture. Overall rate of neonatal asphyxia was 28% in neonates who survived. Higher prevalence of complete uterine ruptures per TOLAC was observed in countries with low previous CS and high TOLAC rates. Rates of hysterectomy and perinatal death are about 10% following complete uterine rupture, but in women undergoing TOLAC the rates are extremely low (only 2.2 and 3.2 per 10 000 TOLACs, respectively.) TWEETABLE ABSTRACT: Prevalence of complete uterine rupture is higher in countries with low previous CS and high TOLAC rates. © 2018 Royal College of Obstetricians and Gynaecologists.

Uterine rupture: socio-demographic aspects, etiology and therapy at the University Clinic of Gynecology and Obstetrics of the National Donka Hospital in Conakry University Hospital, Guinea.

PubMed

Diallo, M H; Baldé, I S; Mamy, M N; Diallo, B S; Baldé, O; Barry, A B; Keita, N

2017-08-01

Uterine rupture is an obstetric catastrophe that has become rare in developed countries. In developing countries, including Guinea, however, it remains a major concern of obstetricians. The objectives of this work were to calculate the frequency of uterine rupture in our département, describe the women's social and demographic characteristics, identify factors predisposing them to uterine rupture, describe its treatment, and assess maternal and fetal prognosis. Data for this descriptive study were collected in 2 phases, with a retrospective review of files covering the 3-year period from April 1, 2011, to March 31, 2014, followed by prospective data collection for the 6-month period from April 1 to September 30, 2014. This study of uterine rupture took place at the maternity unit of Donka National Hospital (CHU Conakry). We identified 98 cases of uterine rupture among 26 827 births, for a frequency of 0.36%. The women's mean age was 28.4 years (range: 16-43 years). The socio-demographic profile of the women admitted for uterine rupture was that of a housewife (50%), with two or three previous deliveries (41.84%), and who had no prenatal care (58.17%). Most of the ruptures took place in birthing centers, outlying maternity units, or during the journey to reach our reference department (87.16%). Most uterine ruptures were iatrogenic (69.38%) and occurred on an non cicatriciel uterus (62.24%). The rupture was most often complete. Most surgical treatment was conservative, by hysterorrhaphy (80.61%). Four women died, for a lethality rate of 4.80%. Almost all women were admitted without signs of fetal life. The role of uterine rupture in the obstetric activity in this service requires joint and urgent action by all stakeholders in the health system to combat this catastrophic complication that is evidence of a poor quality of obstetric care.

The 2017 Mw8.2 Tres Picos, Mexico Earthquake, an intraslab rupture crossing the Tehuantepec Fracture Zone stopped by a tear in the Cocos Plate

NASA Astrophysics Data System (ADS)

Wei, S.; Zeng, H.; WANG, X.; Qiu, Q.; Wang, T.; Li, L.; Chen, M.; Hermawan, I.; Wang, Y.; Tapponnier, P.; Barbot, S.

2017-12-01

On September 7th 2017, an Mw 8.2 intraslab earthquake ruptured beneath the Tehuantepec seismic gap in the Mexico subduction zone. We conducted a comprehensive investigation to characterize the earthquake rupture, including high-resolution back-projection, mainshock and large aftershocks relocation, aftershock moment tensor inversion, finite rupture model inversion jointly inverted from seismic waveform, static/high-rate GPS and InSAR images, and tsunami modeling. The back-projection results delineate a unilateral northwestward rupture about 150 km in length and 60s in duration, with a stable average rupture speed of 2.8 km/s. To reconcile multiple datasets, we used a two-segment fault geometry with near vertical dip angle (78°), and the second segment strikes slightly northward oriented, to mimic the rupture across the Tehuantepec Fracture Zone (FTZ) that separates the rupture into two segments. The joint inversion shows that the slip southeastern of TFZ dominates the moment release in the depth range of 30-50km during the first 40s. The second rupture segment released about 15% of the total moment, but with relatively larger contribution to the high-rate GPS, static geodetic and tide gauges data. Most of the large aftershocks occurred in the shallower part of the slab, with dominant thrust focal mechanism in agreement with slab bending. In contrast, the mainshock initiated at greater depth inside the slab, on a fault that may have formed near the trench and was reactivated by slab unbending, and was perhaps facilitated by dehydration. The comparison between the rupture model and the free air gravity anomaly suggests that the rupture was blocked westward by a low gravity anomaly zone. We interpret the difference in subducting speed and slab age across the TFZ and the Cocos plate gravity anomaly to be responsible for the abrupt stopping of the rupture at a tear zone inside the diving Cocos plate. Whether this earthquake will enhance future rupture on the plate interface in Tehuantepec seismic gap is not clear, as the corresponding stress change clamped the megathrust up-dip. Still, the recent seismic activity raises concern about the imminent seismic hazards in the region.

Constraining Earthquake Source Parameters in Rupture Patches and Rupture Barriers on Gofar Transform Fault, East Pacific Rise from Ocean Bottom Seismic Data

NASA Astrophysics Data System (ADS)

Moyer, P. A.; Boettcher, M. S.; McGuire, J. J.; Collins, J. A.

2015-12-01

On Gofar transform fault on the East Pacific Rise (EPR), Mw ~6.0 earthquakes occur every ~5 years and repeatedly rupture the same asperity (rupture patch), while the intervening fault segments (rupture barriers to the largest events) only produce small earthquakes. In 2008, an ocean bottom seismometer (OBS) deployment successfully captured the end of a seismic cycle, including an extensive foreshock sequence localized within a 10 km rupture barrier, the Mw 6.0 mainshock and its aftershocks that occurred in a ~10 km rupture patch, and an earthquake swarm located in a second rupture barrier. Here we investigate whether the inferred variations in frictional behavior along strike affect the rupture processes of 3.0 < M < 4.5 earthquakes by determining source parameters for 100 earthquakes recorded during the OBS deployment.Using waveforms with a 50 Hz sample rate from OBS accelerometers, we calculate stress drop using an omega-squared source model, where the weighted average corner frequency is derived from an empirical Green's function (EGF) method. We obtain seismic moment by fitting the omega-squared source model to the low frequency amplitude of individual spectra and account for attenuation using Q obtained from a velocity model through the foreshock zone. To ensure well-constrained corner frequencies, we require that the Brune [1970] model provides a statistically better fit to each spectral ratio than a linear model and that the variance is low between the data and model. To further ensure that the fit to the corner frequency is not influenced by resonance of the OBSs, we require a low variance close to the modeled corner frequency. Error bars on corner frequency were obtained through a grid search method where variance is within 10% of the best-fit value. Without imposing restrictive selection criteria, slight variations in corner frequencies from rupture patches and rupture barriers are not discernable. Using well-constrained source parameters, we find an average stress drop of 5.7 MPa in the aftershock zone compared to values of 2.4 and 2.9 MPa in the foreshock and swarm zones respectively. The higher stress drops in the rupture patch compared to the rupture barriers reflect systematic differences in along strike fault zone properties on Gofar transform fault.

Demonstration of improved seismic source inversion method of tele-seismic body wave

NASA Astrophysics Data System (ADS)

Yagi, Y.; Okuwaki, R.

2017-12-01

Seismic rupture inversion of tele-seismic body wave has been widely applied to studies of large earthquakes. In general, tele-seismic body wave contains information of overall rupture process of large earthquake, while the tele-seismic body wave is inappropriate for analyzing a detailed rupture process of M6 7 class earthquake. Recently, the quality and quantity of tele-seismic data and the inversion method has been greatly improved. Improved data and method enable us to study a detailed rupture process of M6 7 class earthquake even if we use only tele-seismic body wave. In this study, we demonstrate the ability of the improved data and method through analyses of the 2016 Rieti, Italy earthquake (Mw 6.2) and the 2016 Kumamoto, Japan earthquake (Mw 7.0) that have been well investigated by using the InSAR data set and the field observations. We assumed the rupture occurring on a single fault plane model inferred from the moment tensor solutions and the aftershock distribution. We constructed spatiotemporal discretized slip-rate functions with patches arranged as closely as possible. We performed inversions using several fault models and found that the spatiotemporal location of large slip-rate area was robust. In the 2016 Kumamoto, Japan earthquake, the slip-rate distribution shows that the rupture propagated to southwest during the first 5 s. At 5 s after the origin time, the main rupture started to propagate toward northeast. First episode and second episode correspond to rupture propagation along the Hinagu fault and the Futagawa fault, respectively. In the 2016 Rieti, Italy earthquake, the slip-rate distribution shows that the rupture propagated to up-dip direction during the first 2 s, and then rupture propagated toward northwest. From both analyses, we propose that the spatiotemporal slip-rate distribution estimated by improved inversion method of tele-seismic body wave has enough information to study a detailed rupture process of M6 7 class earthquake.

Progressive failure during the 1596 Keicho earthquakes on the Median Tectonic Line active fault zone, southwest Japan

NASA Astrophysics Data System (ADS)

Ikeda, M.; Toda, S.; Nishizaka, N.; Onishi, K.; Suzuki, S.

2015-12-01

Rupture patterns of a long fault system are controlled by spatial heterogeneity of fault strength and stress associated with geometrical characteristics and stress perturbation history. Mechanical process for sequential ruptures and multiple simultaneous ruptures, one of the characteristics of a long fault such as the North Anatolian fault, governs the size and frequency of large earthquakes. Here we introduce one of the cases in southwest Japan and explore what controls rupture initiation, sequential ruptures and fault branching on a long fault system. The Median Tectonic Line active fault zone　(hereinafter MTL) is the longest and most active fault in Japan. Based on historical accounts, a series of M ≥ 7 earthquakes occurred on at least a 300-km-long portion of the MTL in 1596. On September 1, the first event occurred on the Kawakami fault segment, in Central Shikoku, and the subsequent events occurred further west. Then on September 5, another rupture initiated from the Central to East Shikoku and then propagated toward the Rokko-Awaji fault zone to Kobe, a northern branch of the MTL, instead of the eastern main extent of the MTL. Another rupture eventually extended to near Kyoto. To reproduce this progressive failure, we applied two numerical models: one is a coulomb stress transfer; the other is a slip-tendency analysis under the tectonic stress. We found that Coulomb stress imparted from historical ruptures have triggered the subsequent ruptures nearby. However, stress transfer does not explain beginning of the sequence and rupture directivities. Instead, calculated slip-tendency values show highly variable along the MTL: high and low seismic potential in West and East Shikoku. The initiation point of the 1596 progressive failure locates near the boundary in the slip-tendency values. Furthermore, the slip-tendency on the Rokko-Awaji fault zone is far higher than that of the MTL in Wakayama, which may explain the rupture directivity toward Kobe-Kyoto.

Rupture Processes of the Mw8.3 Sea of Okhotsk Earthquake and Aftershock Sequences from 3-D Back Projection Imaging

NASA Astrophysics Data System (ADS)

Jian, P. R.; Hung, S. H.; Meng, L.

2014-12-01

On May 24, 2013, the largest deep earthquake ever recorded in history occurred on the southern tip of the Kamchatka Island, where the Pacific Plate subducts underneath the Okhotsk Plate. Previous 2D beamforming back projection (BP) of P- coda waves suggests the mainshock ruptured bilaterally along a horizontal fault plane determined by the global centroid moment tensor solution. On the other hand, the multiple point source inversion of P and SH waveforms argued that the earthquake comprises a sequence of 6 subevents not located on a single plane but actually distributed in a zone that extends 64 km horizontally and 35 km in depth. We then apply a three-dimensional MUSIC BP approach to resolve the rupture processes of the manishock and two large aftershocks (M6.7) with no a priori setup of preferential orientations of the planar rupture. The maximum pseudo-spectrum of high-frequency P wave in a sequence of time windows recorded by the densely-distributed stations from US and EU Array are used to image 3-D temporal and spatial rupture distribution. The resulting image confirms that the nearly N-S striking but two antiparallel rupture stages. The first subhorizontal rupture initially propagates toward the NNE direction, while at 18 s later it directs reversely to the SSW and concurrently shifts downward to 35 km deeper lasting for about 20 s. The rupture lengths in the first NNE-ward and second SSW-ward stage are about 30 km and 85 km; the estimated rupture velocities are 3 km/s and 4.25 km/s, respectively. Synthetic experiments are undertaken to assess the capability of the 3D MUSIC BP for the recovery of spatio-temporal rupture processes. Besides, high frequency BP images based on the EU-Array data show two M6.7 aftershocks are more likely to rupture on the vertical fault planes.

Three-Dimensional Stress Fields and Slip Systems for Single Crystal Superalloy Notched Specimens

NASA Technical Reports Server (NTRS)

Magnan, Shannon M.; Throckmorton, David (Technical Monitor)

2002-01-01

Single crystal superalloys have become increasingly popular for turbine blade and vane applications due to their high strength, and creep and fatigue resistance at elevated temperatures. The crystallographic orientation of a single crystal material greatly affects its material properties, including elastic modulus, shear modulus, and ductility. These directional properties, along with the type of loading and temperature, dictate an anisotropic response in the yield strength, creep resistance, creep rupture ductility, fatigue resistance, etc. A significant amount of research has been conducted to determine the material properties in the <001> orientation, yet the material properties deviating from the <001> orientation have not been assessed for all cases. Based on the desired application and design criteria, a crystal orientation is selected to yield the maximum properties. Currently, single crystal manufacturing is able to control the primary crystallographic orientation within 15 of the target orientation, which is an acceptable deviation to meet both performance and cost guidelines; the secondary orientation is rarely specified. A common experiment is the standard load-controlled tensile test, in which specimens with different orientations can be loaded to observe the material response. The deformation behavior of single-crystal materials under tension and compression is known to be a function of not only material orientation, but also of varying microdeformation (i.e. dislocation) mechanisms. The underlying dislocation motion causes deformation via slip, and affects the activation of specific slip systems based on load and orientation. The slip can be analyzed by observing the visible traces left on the surface of the specimen from the slip activity within the single crystal material. The goal of this thesis was to predict the slip systems activated in three-dimensional stress fields of a notched tensile specimen, as a function of crystal orientation, using finite element analysis without addressing microstructural deformation mechanisms that govern their activation. Out of three orientations tested, the specimen with a [110] load orientation and a [001] growth direction had the lowest maximum resolved shear stress; this specimen orientation appears to be the best design candidate for a tensile application.

[Spontaneous rupture of the spleen in infectious mononucleosis: case report and review of the literature].

PubMed

Kuzman, Ilija; Kirac, Petar; Kuzman, Tomislav; Puljiz, Ivan; Bilić, Vide

2003-01-01

Spontaneous splenic rupture is a rare but potentially fatal complication of infectious mononucleosis. Abdominal pain is uncommon in infectious mononucleosis, and splenic rupture should be strongly considered whenever abdominal pain occurs. The onset of pain may be insidious or abrupt. The pain is usually in the left upper quadrant. To indicate that infectious mononucleosis is not always the innocent kissing disease, but could be complicated with splenic rupture as a life-threathenig condition. Our first case is described and a short literature review is provided. We report on the case of a 27-year-old man with infectious mononucleosis who had spontaneous splenic rupture that was successfully managed by splenectomy. On admission, he was febrile (38.5 degrees C) with hepatosplenomegaly, and had a blood pressure of 100/70 mm Hg. Six hours later, the patient complained of increasing abdominal pain. Abdominal ultrasound and computed tomography showed a 16.5 cm heterogeneous splenomegaly with subcapsular hematoma as well as free ascites. Laparotomy confirmed spontaneous rupture of the splenic capsule with active abdominal bleeding. Splenectomy was performed with a good clinical response. Examination of the spleen revealed a ruptured capsule with a subcapsular hematoma. Infectious mononucleosis is the most common infectious disease to result in spontaneous spleen rupture. The prognosis is favorable when diagnosis is made on time and correct treatment is started immediately. Although splenectomy was advocated as definitive therapy in the past, numerous recent reports have documented good outcomes with non-operative management. Based on the literature review, an approach to the management of a spontaneously ruptured spleen secondary to infectious mononucleosis is suggested. Non-operative management can be successful in hemodynamically stable patients, i.e. in patients with subcapsular hematoma without overt rupture of the capsule to avoid complications of splenectomy (e.g. post-splenectomy sepsis). We report on a 27-year-old man with infectious mononucleosis who had spontaneous splenic rupture that was successfully managed by splenectomy.

Effect of thermal pressurization on dynamic rupture propagation under depth-dependent stress

NASA Astrophysics Data System (ADS)

Urata, Y.; Kuge, K.; Kase, Y.

2009-12-01

Fluid and pore pressure evolution can affect dynamic propagation of earthquake ruptures owing to thermal pressurization (e.g., Mase and Smith, 1985). We investigate dynamic rupture propagation with thermal pressurization on a fault subjected to depth-dependent stress, on the basis of 3-D numerical simulations for spontaneous dynamic ruptures. We put a vertical strike-slip rectangular fault in a semi-infinite, homogenous, and elastic medium. The length and width of the fault are 8 and 3 km, respectively. We assume a depth-dependent stress estimated by Yamashita et al. (2004). The numerical algorithm is based on the finite-difference method by Kase and Kuge (2001). A rupture is initiated by increasing shear stress in a small patch at the bottom of the fault, and then proceeds spontaneously, governed by a slip-weakening law with the Coulomb failure criteria. Coefficients of friction and Dc are homogeneous on the fault. On a fault with thermal pressurization, we allow effective normal stress to vary with pore pressure change due to frictional heating by the formulation of Bizzarri and Cocco (2006). When thermal pressurization does not work, tractions drop in the same way everywhere and rupture velocity is subshear except near the free surface. Due to thermal pressurization, dynamic friction on the fault decreases and is heterogeneous not only vertically but horizontally, slip increases, and rupture velocity along the strike direction becomes supershear. As a result, plural peaks of final slip appear, as observed in the case of undrained dip-slip fault by Urata et al. (2008). We found in this study that the early stage of rupture growth under the depth-dependent stress is affected by the location of an initial crack. When a rupture is initiated at the center of the fault without thermal pressurization, the rupture cannot propagate and terminates. Thermal pressurization can help such a powerless rupture to keep propagating.

Tissue engineering human small-caliber autologous vessels using a xenogenous decellularized connective tissue matrix approach: preclinical comparative biomechanical studies.

PubMed

Heine, Jörg; Schmiedl, Andreas; Cebotari, Serghei; Karck, Matthias; Mertsching, Heike; Haverich, Axel; Kallenbach, Klaus

2011-10-01

Suggesting that bioartificial vascular scaffolds cannot but tissue-engineered vessels can withstand biomechanical stress, we developed in vitro methods for preclinical biological material testings. The aim of the study was to evaluate the influence of revitalization of xenogenous scaffolds on biomechanical stability of tissue-engineered vessels. For measurement of radial distensibility, a salt-solution inflation method was used. The longitudinal tensile strength test (DIN 50145) was applied on bone-shaped specimen: tensile/tear strength (SigmaB/R), elongation at maximum yield stress/rupture (DeltaB/R), and modulus of elasticity were determined of native (NAs; n = 6), decellularized (DAs; n = 6), and decellularized carotid arteries reseeded with human vascular smooth muscle cells and human vascular endothelial cells (RAs; n = 7). Radial distensibility of DAs was significantly lower (113%) than for NAs (135%) (P < 0.001) or RAs (127%) (P = 0.018). At levels of 120 mm Hg and more, decellularized matrices burst (120, 160 [n = 2] and 200 mm Hg). Although RAs withstood levels up to 300 mm Hg, ANOVA revealed a significant difference from NA (P = 0.018). Compared with native vessels (NAs), SigmaB/R values were lower in DAs (44%; 57%) (P = 0.014 and P = 0.002, respectively) and were significantly higher in RAs (71%; 83%) (both P < 0.001). Similarly, DeltaB/R values were much higher in DAs compared with NAs (94%; 88%) (P < 0.001) and RAs (87%; 103%) (P < 0.001), but equivalent in NAs and RAs. Modulus of elasticity (2.6/1.1/3.7 to 16.6 N/mm(2)) of NAs, DAs, RAs was comparable (P = 0.088). Using newly developed in vitro methods for small-caliber vascular graft testing, this study proved that revitalization of decellularized connective tissue scaffolds led to vascular graft stability able to withstand biomechanical stress mimicking the human circulation. This tissue engineering approach provides a sufficiently stable autologized graft. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Effect of single-particle magnetostriction on the shear modulus of compliant magnetoactive elastomers.

PubMed

Kalita, Viktor M; Snarskii, Andrei A; Shamonin, Mikhail; Zorinets, Denis

2017-03-01

The influence of an external magnetic field on the static shear strain and the effective shear modulus of a magnetoactive elastomer (MAE) is studied theoretically in the framework of a recently introduced approach to the single-particle magnetostriction mechanism [V. M. Kalita et al., Phys. Rev. E 93, 062503 (2016)10.1103/PhysRevE.93.062503]. The planar problem of magnetostriction in an MAE with magnetically soft inclusions in the form of a thin disk (platelet) having the magnetic anisotropy in the plane of this disk is solved analytically. An external magnetic field acts with torques on magnetic filler particles, creates mechanical stresses in the vicinity of inclusions, induces shear strain, and increases the effective shear modulus of these composite materials. It is shown that the largest effect of the magnetic field on the effective shear modulus should be expected in MAEs with soft elastomer matrices, where the shear modulus of the matrix is less than the magnetic anisotropy constant of inclusions. It is derived that the effective shear modulus is nonlinearly dependent on the external magnetic field and approaches the saturation value in magnetic fields exceeding the field of particle anisotropy. It is shown that model calculations of the effective shear modulus correspond to a phenomenological definition of effective elastic moduli and magnetoelastic coupling constants. The obtained theoretical results compare well with known experimental data. Determination of effective elastic coefficients in MAEs and their dependence on magnetic field is discussed. The concentration dependence of the effective shear modulus at higher filler concentrations has been estimated using the method of Padé approximants, which predicts that both the absolute and relative changes of the magnetic-field-dependent effective shear modulus will significantly increase with the growing concentration of filler particles.

Effect of single-particle magnetostriction on the shear modulus of compliant magnetoactive elastomers

NASA Astrophysics Data System (ADS)

Kalita, Viktor M.; Snarskii, Andrei A.; Shamonin, Mikhail; Zorinets, Denis

2017-03-01

The influence of an external magnetic field on the static shear strain and the effective shear modulus of a magnetoactive elastomer (MAE) is studied theoretically in the framework of a recently introduced approach to the single-particle magnetostriction mechanism [V. M. Kalita et al., Phys. Rev. E 93, 062503 (2016), 10.1103/PhysRevE.93.062503]. The planar problem of magnetostriction in an MAE with magnetically soft inclusions in the form of a thin disk (platelet) having the magnetic anisotropy in the plane of this disk is solved analytically. An external magnetic field acts with torques on magnetic filler particles, creates mechanical stresses in the vicinity of inclusions, induces shear strain, and increases the effective shear modulus of these composite materials. It is shown that the largest effect of the magnetic field on the effective shear modulus should be expected in MAEs with soft elastomer matrices, where the shear modulus of the matrix is less than the magnetic anisotropy constant of inclusions. It is derived that the effective shear modulus is nonlinearly dependent on the external magnetic field and approaches the saturation value in magnetic fields exceeding the field of particle anisotropy. It is shown that model calculations of the effective shear modulus correspond to a phenomenological definition of effective elastic moduli and magnetoelastic coupling constants. The obtained theoretical results compare well with known experimental data. Determination of effective elastic coefficients in MAEs and their dependence on magnetic field is discussed. The concentration dependence of the effective shear modulus at higher filler concentrations has been estimated using the method of Padé approximants, which predicts that both the absolute and relative changes of the magnetic-field-dependent effective shear modulus will significantly increase with the growing concentration of filler particles.

The 2016 Kaikōura earthquake: Simultaneous rupture of the subduction interface and overlying faults

NASA Astrophysics Data System (ADS)

Wang, Teng; Wei, Shengji; Shi, Xuhua; Qiu, Qiang; Li, Linlin; Peng, Dongju; Weldon, Ray J.; Barbot, Sylvain

2018-01-01

The distribution of slip during an earthquake and how it propagates among faults in the subduction system play a major role in seismic and tsunami hazards, yet they are poorly understood because offshore observations are often lacking. Here we derive the slip distribution and rupture evolution during the 2016 Mw 7.9 Kaikōura (New Zealand) earthquake that reconcile the surface rupture, space geodetic measurements, seismological and tsunami waveform records. We use twelve fault segments, with eleven in the crust and one on the megathrust interface, to model the geodetic data and match the major features of the complex surface ruptures. Our modeling result indicates that a large portion of the moment is distributed on the subduction interface, making a significant contribution to the far field surface deformation and teleseismic body waves. The inclusion of local strong motion and teleseismic waveform data in the joint inversion reveals a unilateral rupture towards northeast with a relatively low averaged rupture speed of ∼1.5 km/s. The first 30 s of the rupture took place on the crustal faults with oblique slip motion and jumped between fault segments that have large differences in strike and dip. The peak moment release occurred at ∼65 s, corresponding to simultaneous rupture of both plate interface and the overlying splay faults with rake angle changes progressively from thrust to strike-slip. The slip on the Papatea fault produced more than 2 m of offshore uplift, making a major contribution to the tsunami at the Kaikōura station, while the northeastern end of the rupture can explain the main features at the Wellington station. Our inversions and simulations illuminate complex up-dip rupture behavior that should be taken into consideration in both seismic and tsunami hazard assessment. The extreme complex rupture behavior also brings new challenges to the earthquake dynamic simulations and understanding the physics of earthquakes.

Empirical potential influence and effect of temperature on the mechanical properties of pristine and defective hexagonal boron nitride

NASA Astrophysics Data System (ADS)

Thomas, Siby; Ajith, K. M.; Valsakumar, M. C.

2017-06-01

The major objective of this work is to present results of a classical molecular dynamics study to investigate the effect of changing the cut-off distance in the empirical potential on the stress-strain relation and also the temperature dependent Young’s modulus of pristine and defective hexagonal boron nitride. As the temperature increases, the computed Young’s modulus shows a significant decrease along both the armchair and zigzag directions. The computed Young’s modulus shows a trend in keeping with the structural anisotropy of h-BN. The variation of Young’s modulus with system size is elucidated. The observed mechanical strength of h-BN is significantly affected by the vacancy and Stone-Wales type defects. The computed room temperature Young’s modulus of pristine h-BN is 755 GPa and 769 GPa respectively along the armchair and zigzag directions. The decrease of Young’s modulus with increase in temperature has been analyzed and the results show that the system with zigzag edge shows a higher value of Young’s modulus in comparison to that with armchair edge. As the temperature increases, the computed stiffness decreases and the system with zigzag edge possesses a higher value of stiffness as compared to the armchair counterpart and this behaviour is consistent with the variation of Young’s modulus. The defect analysis shows that presence of vacancy type defects leads to a higher Young’s modulus, in the studied range with different percentage of defect concentration, in comparison with Stone-Wales defect. The variations in the peak position of the computed radial distribution function reveals the changes in the structural features of systems with zigzag and armchair edges in the presence of applied stress.

Use of fluroquinolone and risk of Achilles tendon rupture: a population-based cohort study.

PubMed

Sode, Jacob; Obel, Niels; Hallas, Jesper; Lassen, Annmarie

2007-05-01

Several case-control studies have reported that the use of fluoroquinolone increases the risk of rupture of the Achilles tendon. Our aim was to estimate this risk by means of a population-based cohort approach. Data on Achilles tendon ruptures and fluoroquinolone use were retrieved from three population-based databases that include information on residents of Funen County (population: 470,000) in primary and secondary care during the period 1991-1999. A study cohort of all 28,262 first-time users of fluoroquinolone and all incident cases of Achilles tendon ruptures were identified. The incidence rate of Achilles tendon ruptures among users and non-users of fluoroquinolones and the standardised incidence rate ratio associating fluoroquinolon use with Achilles tendon rupture were the main outcome measures. Between 1991 and 2002 the incidence of Achilles tendon rupture increased from 22.1 to 32.6/100,000 person-years. Between 1991 and 1999 the incidence of fluoroquinolone users was 722/100,000 person-years, with no apparent trend over time. Within 90 days of their first use of fluoroquinolone, five individuals had a rupture of the Achilles tendon; the expected number was 1.6, yielding an age- and sex-standardised incidence ratio of 3.1 [(95% confidence interval (95%CI): 1.0-7.3). The 90-day cumulative incidence of Achilles tendon ruptures among fluoroquinolone users was 17.7/100,000 (95%CI: 5.7-41.3), which is an increase of 12.0/100,000 (95%CI: 0.0-35.6) compared to the background population. Fluoroquinolone use triples the risk of Achilles tendon rupture, but the incidence among users is low.

Resilient modulus for New Hampshire subgrade soils for use in mechanistic AASHTO design

DOT National Transportation Integrated Search

1999-09-01

Resilient modulus tests were conducted on five subgrade soils commonly found in the state of New Hampshire. Tests were conducted on samples prepared at optimum density and moisture content. To determine the effective resilient modulus of the various ...

Developing an economical and reliable test for measuring the resilient modulus and Poisson's ratio of subgrade.

DOT National Transportation Integrated Search

2010-11-01

The resilient modulus and Poissons ratio of base and sublayers in highway use are : important parameters in design and quality control process. The currently used techniques : include CBR (California Bearing Ratio) test, resilient modulus test,...

Dynamic rupture simulations on a fault network in the Corinth Rift

NASA Astrophysics Data System (ADS)

Durand, V.; Hok, S.; Boiselet, A.; Bernard, P.; Scotti, O.

2017-03-01

The Corinth rift (Greece) is made of a complex network of fault segments, typically 10-20 km long separated by stepovers. Assessing the maximum magnitude possible in this region requires accounting for multisegment rupture. Here we apply numerical models of dynamic rupture to quantify the probability of a multisegment rupture in the rift, based on the knowledge of the fault geometry and on the magnitude of the historical and palaeoearthquakes. We restrict our application to dynamic rupture on the most recent and active fault network of the western rift, located on the southern coast. We first define several models, varying the main physical parameters that control the rupture propagation. We keep the regional stress field and stress drop constant, and we test several fault geometries, several positions of the faults in their seismic cycle, several values of the critical distance (and so several fracture energies) and two different hypocentres (thus testing two directivity hypothesis). We obtain different scenarios in terms of the number of ruptured segments and the final magnitude (between M = 5.8 for a single segment rupture to M = 6.4 for a whole network rupture), and find that the main parameter controlling the variability of the scenarios is the fracture energy. We then use a probabilistic approach to quantify the probability of each generated scenario. To do that, we implement a logical tree associating a weight to each model input hypothesis. Combining these weights, we compute the probability of occurrence of each scenario, and show that the multisegment scenarios are very likely (52 per cent), but that the whole network rupture scenario is unlikely (14 per cent).

Presence of Bacteria in Spontaneous Achilles Tendon Ruptures.

PubMed

Rolf, Christer G; Fu, Sai-Chuen; Hopkins, Chelsea; Luan, Ju; Ip, Margaret; Yung, Shu-Hang; Friman, Göran; Qin, Ling; Chan, Kai-Ming

2017-07-01

The structural pathology of Achilles tendon (AT) ruptures resembles tendinopathy, but the causes remain unknown. Recently, a number of diseases were found to be attributed to bacterial infections, resulting in low-grade inflammation and progressive matrix disturbance. The authors speculate that spontaneous AT ruptures may also be influenced by the presence of bacteria. Bacteria are present in ruptured ATs but not in healthy tendons. Cross-sectional study; Level of evidence, 3. Patients with spontaneous AT ruptures and patients undergoing anterior cruciate ligament (ACL) reconstruction were recruited for this study. During AT surgical repair, excised tendinopathic tissue was collected, and healthy tendon samples were obtained as controls from hamstring tendon grafts used in ACL reconstruction. Half of every sample was reserved for DNA extraction and the other half for histology. Polymerase chain reaction (PCR) was conducted using 16S rRNA gene universal primers, and the PCR products were sequenced for the identification of bacterial species. A histological examination was performed to compare tendinopathic changes in the case and control samples. Five of 20 AT rupture samples were positive for the presence of bacterial DNA, while none of the 23 hamstring tendon samples were positive. Sterile operating and experimental conditions and tests on samples, controlling for harvesting and processing procedures, ruled out the chance of postoperative bacterial contamination. The species identified predominantly belonged to the Staphylococcus genus. AT rupture samples exhibited histopathological features characteristic of tendinopathy, and most healthy hamstring tendon samples displayed normal tendon features. There were no apparent differences in histopathology between the bacterial DNA-positive and bacterial DNA-negative AT rupture samples. The authors have demonstrated the presence of bacterial DNA in ruptured AT samples. It may suggest the potential involvement of bacteria in spontaneous AT ruptures.

Rupture Dynamics and Scaling Behavior of Hydraulically Stimulated Micro-Earthquakes in a Shale Reservoir

NASA Astrophysics Data System (ADS)

Viegas, G. F.; Urbancic, T.; Baig, A. M.

2014-12-01

In hydraulic fracturing completion programs fluids are injected under pressure into fractured rock formations to open escape pathways for trapped hydrocarbons along pre-existing and newly generated fractures. To characterize the failure process, we estimate static and dynamic source and rupture parameters, such as dynamic and static stress drop, radiated energy, seismic efficiency, failure modes, failure plane orientations and dimensions, and rupture velocity to investigate the rupture dynamics and scaling relations of micro-earthquakes induced during a hydraulic fracturing shale completion program in NE British Columbia, Canada. The relationships between the different parameters combined with the in-situ stress field and rock properties provide valuable information on the rupture process giving insights into the generation and development of the fracture network. Approximately 30,000 micro-earthquakes were recorded using three multi-sensor arrays of high frequency geophones temporarily placed close to the treatment area at reservoir depth (~2km). On average the events have low radiated energy, low dynamic stress and low seismic efficiency, consistent with the obtained slow rupture velocities. Events fail in overshoot mode (slip weakening failure model), with fluids lubricating faults and decreasing friction resistance. Events occurring in deeper formations tend to have faster rupture velocities and are more efficient in radiating energy. Variations in rupture velocity tend to correlate with variation in depth, fault azimuth and elapsed time, reflecting a dominance of the local stress field over other factors. Several regions with different characteristic failure modes are identifiable based on coherent stress drop, seismic efficiency, rupture velocities and fracture orientations. Variations of source parameters with rock rheology and hydro-fracture fluids are also observed. Our results suggest that the spatial and temporal distribution of events with similar characteristic rupture behaviors can be used to determine reservoir geophysical properties, constrain reservoir geo-mechanical models, classify dynamic rupture processes for fracture models and improve fracture treatment designs.

The Atmospheric Pressure and Temperature Seem to Have No Effect on the Incidence of Rupture of Abdominal Aortic Aneurysm in a Mid-European Region.

PubMed

Majd, Payman; Ahmad, Wael; Luebke, Thomas; Brunkwall, Jan Sigge

2017-07-01

This study aims to examine the relationship between weather changes (atmospheric pressure and temperature) and incidence of rupture of abdominal aortic aneurysm (AAA). All patients with ruptured infrarenal AAA and who were referred to our institution between August 1998 and August 2015 were prospectively entered into a database of which a retrospective review of a ruptured AAA was performed. The needed information about the daily atmospheric pressure and air temperature could be extracted from the meteorological unit in Cologne. During the study period (6,225 days), a total number of 154 patients with confirmed ruptured AAA were identified. Basic patients' characteristics are tabulated. The mean daily atmospheric pressure during the study was 1,004.04 ± 8.79 mBar ranging from 965.40-1031.80 mBar. The mean atmospheric pressure on the days of rupture was 1,004.03 vs. 1,004.68 on those days when no rupture occurred (P = 0.34). The mean atmospheric pressure on the day of rupture and that on the preceding day was not significantly different (1,004.78 vs. 1,005.44 with P = 0.13). The air temperature (10.62 ± 6.25 vs. 10.77 ± 6.83°C, P = 0.787) was equally distributed between days of rupture events and control days. The present study could not show a significant association between the monthly and seasonal difference in atmospheric pressure and the prevalence of AAA rupture as it has been supposed by previous studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Assessment of vulnerable plaque composition by matching the deformation of a parametric plaque model to measured plaque deformation.

PubMed

Baldewsing, Radj A; Schaar, Johannes A; Mastik, Frits; Oomens, Cees W J; van der Steen, Antonius F W

2005-04-01

Intravascular ultrasound (IVUS) elastography visualizes local radial strain of arteries in so-called elastograms to detect rupture-prone plaques. However, due to the unknown arterial stress distribution these elastograms cannot be directly interpreted as a morphology and material composition image. To overcome this limitation we have developed a method that reconstructs a Young's modulus image from an elastogram. This method is especially suited for thin-cap fibroatheromas (TCFAs), i.e., plaques with a media region containing a lipid pool covered by a cap. Reconstruction is done by a minimization algorithm that matches the strain image output, calculated with a parametric finite element model (PFEM) representation of a TCFA, to an elastogram by iteratively updating the PFEM geometry and material parameters. These geometry parameters delineate the TCFA media, lipid pool and cap regions by circles. The material parameter for each region is a Young's modulus, EM, EL, and EC, respectively. The method was successfully tested on computer-simulated TCFAs (n = 2), one defined by circles, the other by tracing TCFA histology, and additionally on a physical phantom (n = 1) having a stiff wall (measured EM = 16.8 kPa) with an eccentric soft region (measured EL = 4.2 kPa). Finally, it was applied on human coronary plaques in vitro (n = 1) and in vivo (n = 1). The corresponding simulated and measured elastograms of these plaques showed radial strain values from 0% up to 2% at a pressure differential of 20, 20, 1, 20, and 1 mmHg respectively. The used/reconstructed Young's moduli [kPa] were for the circular plaque EL = 50/66, EM = 1500/1484, EC = 2000/2047, for the traced plaque EL = 25/1, EM = 1000/1148, EC = 1500/1491, for the phantom EL = 4.2/4 kPa, EM = 16.8/16, for the in vitro plaque EL = n.a./29, EM = n.a./647, EC = n.a./1784 kPa and for the in vivo plaque EL = n.a./2, EM = n.a./188, Ec = n.a./188 kPa.

Pore pressure may control rupture propagation of the 2001 Mw=7.8 Kokoxili earthquake from the Kunlun fault to the Kunlun Pass fault

NASA Astrophysics Data System (ADS)

Xiao, J.; Wang, W.; He, J.

2016-12-01

The 2001 Mw=7.8 Kokoxili earthquake nucleated on the west-east tending Kunlun strike-slip fault in center of the Tibetan plateau. When the rupture propagated eastward near the Xidatan segment of the Kunlun fault, this earthquake jumped to the Kunlun Pass fault, a less matured fault that, due to the geometric orientation, was obviously clamped by the coseismic deformation before its rupture. To investigate the possible mechanism for the rupture jump, we updated the coseismic rupture model from a joint inversion of the geological, geodetic and seismic wave data. Constrained with the rupture process, a three-dimensional finite element model was developed to calculate the failure stress from elastic and poroelastic deformation of the crust during the rupture propagation. Results show that just before the rupture reached the conjunction of the Xidatan segment and the Kunlun Pass fault, the failure stress induced by elastic deformation is indeed larger on Xidatan segment of the Kunlun fault than on the Kunlun Pass fault. However, if the pore pressure resulted from undrained poroelastic deformation was invoked, the failure stress is significantly increased on the Kunlun Pass fault. Given a reasonable bound on fault friction and on poroelastic parameters, it can be seen that the poroelastic failure stress is 0.3-0.9 Mpa greater on the Kunlun Pass fault than on Xidatan segment of the Kunlun fault. We therefore argue that during the rupture process of the 2001 Mw=7.8 Kokoxili earthquake, pore pressure may play an important role on controlling the rupture propagation from the Kunlun fault to the Kunlun Pass fault.

Rupture Dynamics along Thrust Dipping Fault: Inertia Effects due to Free Surface Wave Interactions

NASA Astrophysics Data System (ADS)

Vilotte, J. P.; Scala, A.; Festa, G.

2017-12-01

We numerically investigate the dynamic interaction between free surface and up-dip, in-plane rupture propagation along thrust faults, under linear slip-weakening friction. With reference to shallow along-dip rupture propagation during large subduction earthquakes, we consider here low dip-angle fault configurations with fixed strength excess and depth-increasing initial stress. In this configuration, the rupture undergoes a break of symmetry with slip-induced normal stress perturbations triggered by the interaction with reflected waves from the free surface. We found that both body-waves - behind the crack front - and surface waves - at the crack front - can trigger inertial effects. When waves interact with the rupture before this latter reaches its asymptotic speed, the rupture can accelerate toward the asymptotic speed faster than in the unbounded symmetric case, as a result of these inertial effects. Moreover, wave interaction at the crack front also affects the slip rate generating large ground motion on the hanging wall. Imposing the same initial normal stress, frictional strength and stress drop while varying the static friction coefficient we found that the break of symmetry makes the rupture dynamics dependent on the absolute value of friction. The higher the friction the stronger the inertial effect both in terms of rupture acceleration and slip amount. When the contact condition allows the fault interface to open close to the free surface, the length of the opening zone is shown to depend on the propagation length, the initial normal stress and the static friction coefficient. These new results are shown to agree with analytical results of rupture propagation in bounded media, and open new perspectives for understanding the shallow rupture of large subduction earthquakes and tsunami sources.

Hypertrophic remodeling and increased arterial stiffness in patients with intracranial aneurysms.

PubMed

Maltete, David; Bellien, Jeremy; Cabrejo, Lucie; Iacob, Michele; Proust, François; Mihout, Bruno; Thuillez, Christian; Guegan-Massardier, Evelyne; Joannides, Robinson

2010-08-01

Because an underlying arteriopathy might contribute to the development of intracranial aneurysms (IAs), we assessed the elastic properties of proximal conduit arteries in patients with IA. In 27 patients with previous ruptured IA and 27 control subjects matched for age, gender and BMI, we determined arterial pressure, internal diameter, intima-media thickness (IMT), circumferential wall stress (CWS) and elastic modulus (wall stiffness) in common carotid arteries using applanation tonometry and echotracking. Moreover, carotid augmentation index (AIx, arterial wave reflections) and carotid-to-femoral pulse wave velocity (PWV, aortic stiffness) were assessed. Compared with controls, patients with IA exhibited higher brachial and carotid systolic and diastolic blood pressures, with similar brachial but higher carotid artery pulse pressure (35 + or - 6mm Hg vs. 41 + or - 8mm Hg, P=0.014). Moreover, patients have higher PWV (7.8 + or - 1.2ms(-1) vs. 8.3 + or - 1.1ms(-1), P=0.048) and AIx (15.8 + or - 10.8% vs. 21.1 + or - 8.5%, P<0.001) which contributes to increase carotid blood pressures. Furthermore, carotid IMT was higher in patients (546 + or - 64 microm vs. 642 + or - 70 microm, P<0.001) without difference in diameter suggesting an adaptive hypertrophy. However, patients display a lower CWS (61.6 + or - 9.2 kPa vs. 56.9 + or - 10.3 kPa, P=0.007) and no correlation between IMT and pulse pressure (r=0.152, P=NS) in contrast to controls (r=0.539, P<0.001) showing the contribution of a pressure-independent process. Finally, despite this lesser CWS, elastic modulus was increased in patients (310 + or - 105 kPa vs. 383 + or - 174 kPa, P=0.026). This study demonstrates that patients with IA display a particular carotid artery phenotype with an exaggerated hypertrophic remodeling and altered elastic properties. Thus, a systemic arteriopathy might contribute, together with the arterial wall fatiguing effect of the increased pulsatile stress, to the pathogenesis of IA. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Nucleation and dynamic rupture on weakly stressed faults sustained by thermal pressurization

NASA Astrophysics Data System (ADS)

Schmitt, Stuart V.; Segall, Paul; Dunham, Eric M.

2015-11-01

Earthquake nucleation requires that the shear stress τ locally reaches a fault's static strength, fσeff, the product of the friction coefficient and effective normal stress. Once rupture initiates, shear heating-induced thermal pressurization can sustain rupture at much lower τ/σeff ratios, a stress condition believed to be the case during most earthquakes. This requires that earthquakes nucleate at heterogeneities. We model nucleation and dynamic rupture on faults in a 2-D elastic medium with rate/state friction and thermal pressurization, subjected to globally low τ but with local stress heterogeneities that permit nucleation. We examine end-member cases of either high-τ or low-σeff heterogeneities. We find that thermal pressurization can sustain slip at τ/σeff values as low as 0.13, compared to static friction of ˜0.7. Background τ (and, to lesser extent, heterogeneity width) controls whether ruptures arrest or are sustained, with extremely low values resulting in arrest. For a small range of background τ, sustained slip is pulse-like. Cessation of slip in a pulse tail can result from either diffusive restrengthening of σeff or a wave-mediated stopping phase that follows the rupture tip. Slightly larger background τ leads to sustained crack-like rupture. Thermal pressurization is stronger at high-τ heterogeneities, resulting in a lower background τ threshold for sustained rupture and potentially larger arresting ruptures. High-stress events also initiate with higher moment rate, although this may be difficult to observe in nature. For arresting ruptures, stress drops and the dependence of fracture energy on mean slip are both consistent with values inferred for small earthquakes.

Amplification of tsunami heights by delayed rupture of great earthquakes along the Nankai trough

NASA Astrophysics Data System (ADS)

Imai, K.; Satake, K.; Furumura, T.

2010-04-01

We investigated the effect of delayed rupture of great earthquakes along the Nankai trough on tsunami heights on the Japanese coast. As the tsunami source, we used a model of the 1707 Hoei earthquake, which consists of four segments: Tokai, Tonankai, and two Nankai segments. We first searched for the worst case, in terms of coastal tsunami heights, of rupture delay time on each segment, on the basis of superposition principle for the linear long wave theory. When the rupture starts on the Tonankai segment, followed by rupture on the Tokai segment 21 min later, as well as the eastern and western Nankai segments 15 and 28 min later, respectively, the average coastal tsunami height becomes the largest. To quantify the tsunami amplification, we compared the coastal tsunami heights from the delayed rupture with those from the simultaneous rupture model. Along the coasts of the sea of Hyu'uga and in the Bungo Channel, the tsunami heights become significantly amplified (>1.4 times larger) relative to the simultaneous rupture. Along the coasts of Tosa Bay and in the Kii Channel, the tsunami heights become amplified about 1.2 times. Along the coasts of the sea of Kumano and Ise Bay, and the western Enshu coast, the tsunami heights become slightly smaller for the delayed rupture. Along the eastern Enshu coast, the coast of Suruga Bay, and the west coast of Sagami Bay, the tsunami heights become amplified about 1.1 times.

Flexor Tendon Rupture Due to Previously Undiagnosed Kienböck Disease: A Case Report.

PubMed

Turner, Kenrick; Sheppard, Nicholas N; Norton, Samuel E

2017-05-01

Spontaneous flexor tendon rupture is rare and most common in the little finger. The pathogenesis of spontaneous tendon ruptures is unclear but may occur through attrition or mechanical abrasion over a bony prominence. Kienböck disease is avascular necrosis of the lunate, with an unknown etiology. We present a case of spontaneous rupture of flexor digitorum profundus due to Kienböck disease, which we believe is the first recorded case of flexor tendon rupture attributable to osteonecrosis of the lunate. The patient underwent single-stage reconstruction of FDP and regained a good range of motion at the affected DIPJ. This case illustrates the the importance of plain radiographs in the assessment of a patient presenting with spontaneous flexor tendon rupture in the hand to exclude bony pathology as a cause.

Nonoperative management of spontaneous splenic rupture in infectious mononucleosis: a case report and review of the literature.

PubMed

Stephenson, Jacob T; DuBois, Jeffrey J

2007-08-01

Spontaneous rupture of the spleen is a rare complication of infectious mononucleosis with no clear consensus on appropriate management. Although management of traumatic splenic rupture has largely moved to nonoperative treatment, splenectomy is still frequently used in dealing with rupture of the diseased spleen. Here we report the case of a 16-year-old boy with splenic rupture secondary to laboratory-confirmed infectious mononucleosis in the absence of trauma. Nonoperative management including ICU admission, serial computed tomography scans, and activity limitation was used successfully. Our experience, along with a review of the literature, leads us to conclude that splenic preservation can be a safe alternative to splenectomy in hemodynamically stable patients with spontaneous splenic rupture. This is of particular importance in the pediatric population, which is at higher risk for postsplenectomy sepsis.

Rupture Dynamics and Seismic Radiation on Rough Faults for Simulation-Based PSHA

NASA Astrophysics Data System (ADS)

Mai, P. M.; Galis, M.; Thingbaijam, K. K. S.; Vyas, J. C.; Dunham, E. M.

2017-12-01

Simulation-based ground-motion predictions may augment PSHA studies in data-poor regions or provide additional shaking estimations, incl. seismic waveforms, for critical facilities. Validation and calibration of such simulation approaches, based on observations and GMPE's, is important for engineering applications, while seismologists push to include the precise physics of the earthquake rupture process and seismic wave propagation in 3D heterogeneous Earth. Geological faults comprise both large-scale segmentation and small-scale roughness that determine the dynamics of the earthquake rupture process and its radiated seismic wavefield. We investigate how different parameterizations of fractal fault roughness affect the rupture evolution and resulting near-fault ground motions. Rupture incoherence induced by fault roughness generates realistic ω-2 decay for high-frequency displacement amplitude spectra. Waveform characteristics and GMPE-based comparisons corroborate that these rough-fault rupture simulations generate realistic synthetic seismogram for subsequent engineering application. Since dynamic rupture simulations are computationally expensive, we develop kinematic approximations that emulate the observed dynamics. Simplifying the rough-fault geometry, we find that perturbations in local moment tensor orientation are important, while perturbations in local source location are not. Thus, a planar fault can be assumed if the local strike, dip, and rake are maintained. The dynamic rake angle variations are anti-correlated with local dip angles. Based on a dynamically consistent Yoffe source-time function, we show that the seismic wavefield of the approximated kinematic rupture well reproduces the seismic radiation of the full dynamic source process. Our findings provide an innovative pseudo-dynamic source characterization that captures fault roughness effects on rupture dynamics. Including the correlations between kinematic source parameters, we present a new pseudo-dynamic rupture modeling approach for computing broadband ground-motion time-histories for simulation-based PSHA

Fault segmentation: New concepts from the Wasatch Fault Zone, Utah, USA

USGS Publications Warehouse

Duross, Christopher; Personius, Stephen F.; Crone, Anthony J.; Olig, Susan S.; Hylland, Michael D.; Lund, William R.; Schwartz, David P.

2016-01-01

The question of whether structural segment boundaries along multisegment normal faults such as the Wasatch fault zone (WFZ) act as persistent barriers to rupture is critical to seismic hazard analyses. We synthesized late Holocene paleoseismic data from 20 trench sites along the central WFZ to evaluate earthquake rupture length and fault segmentation. For the youngest (<3 ka) and best-constrained earthquakes, differences in earthquake timing across prominent primary segment boundaries, especially for the most recent earthquakes on the north-central WFZ, are consistent with segment-controlled ruptures. However, broadly constrained earthquake times, dissimilar event times along the segments, the presence of smaller-scale (subsegment) boundaries, and areas of complex faulting permit partial-segment and multisegment (e.g., spillover) ruptures that are shorter (~20–40 km) or longer (~60–100 km) than the primary segment lengths (35–59 km). We report a segmented WFZ model that includes 24 earthquakes since ~7 ka and yields mean estimates of recurrence (1.1–1.3 kyr) and vertical slip rate (1.3–2.0 mm/yr) for the segments. However, additional rupture scenarios that include segment boundary spatial uncertainties, floating earthquakes, and multisegment ruptures are necessary to fully address epistemic uncertainties in rupture length. We compare the central WFZ to paleoseismic and historical surface ruptures in the Basin and Range Province and central Italian Apennines and conclude that displacement profiles have limited value for assessing the persistence of segment boundaries but can aid in interpreting prehistoric spillover ruptures. Our comparison also suggests that the probabilities of shorter and longer ruptures on the WFZ need to be investigated.

Surgical Treatment Versus Conservative Management for Acute Achilles Tendon Rupture: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

PubMed

Deng, Senlin; Sun, Zhengyu; Zhang, Chenghao; Chen, Gang; Li, Jian

Acute Achilles tendon ruptures can be treated with surgical and nonsurgical treatment. However, the optimal intervention for acute Achilles tendon rupture remains controversial. The aim of the present study was to compare the clinical outcomes of surgical treatment versus conservative management for acute Achilles tendon rupture. Eight randomized controlled studies involving 762 patients were included in the meta-analysis. In general, re-rupture occurred in 14 of 381 surgically treated patients (3.7%) and 37 of 377 nonsurgically treated patients (9.8%). Pooled results showed that the total re-rupture rate was significantly lower in surgical group than that in the nonsurgical group (risk ratio 0.38, 95% confidence interval 0.21 to 0.68; p = .001). No significant differences were found between the 2 treatment groups in the incidence of deep venous thrombosis, the number who returned to sport, ankle range of motion (dorsiflexion, plantarflexion), Achilles tendon total rupture score, or physical activity scale. Surgical treatment can effectively reduce the re-rupture rate and might be a better choice for the treatment of acute Achilles tendon rupture. Multicenter, double-blind randomized controlled trials with stratification and long-term follow-up are needed to obtain a higher level of evidence and to guide clinical practice, especially in the comparison and selection of different treatments. Copyright © 2017 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Triple Achilles Tendon Rupture: Case Report.

PubMed

Saxena, Amol; Hofer, Deann

We present a case report with 1-year follow-up data of a 57-year-old male soccer referee who had sustained an acute triple Achilles tendon rupture injury during a game. His triple Achilles tendon rupture consisted of a rupture of the proximal watershed region, a rupture of the main body (mid-watershed area), and an avulsion-type rupture of insertional calcific tendinosis. The patient was treated surgically with primary repair of the tendon, including tenodesis with anchors. Postoperative treatment included non-weightbearing for 4 weeks and protected weightbearing until 10 weeks postoperative, followed by formal physical therapy, which incorporated an "antigravity" treadmill. The patient was able to return to full activity after 26 weeks, including running and refereeing, without limitations. Copyright © 2017 The American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

The influence of orientation on the stress rupture properties of nickel-base superalloy single crystals

NASA Technical Reports Server (NTRS)

Mackay, R. A.; Maier, R. D.

1982-01-01

Constant load creep rupture tests were performed on MAR-M247 single crystals at 724 MPa and 774 C where the effect of anisotropy is prominent. The initial orientations of the specimens as well as the final orientations of selected crystals after stress rupture testing were determined by the Laue back-reflection X-ray technique. The stress rupture lives of the MAR-M247 single crystals were found to be largely determined by the lattice rotations required to produce intersecting slip, because second-stage creep does not begin until after the onset of intersecting slip. Crystals which required large rotations to become oriented for intersecting slip exhibited the shortest stress rupture lives, whereas crystals requiring little or no rotations exhibited the lowest minimum creep rates, and consequently, the longest stress rupture lives.

Indentation-derived elastic modulus of multilayer thin films: Effect of unloading induced plasticity

DOE PAGES

Jamison, Ryan Dale; Shen, Yu -Lin

2015-08-13

Nanoindentation is useful for evaluating the mechanical properties, such as elastic modulus, of multilayer thin film materials. A fundamental assumption in the derivation of the elastic modulus from nanoindentation is that the unloading process is purely elastic. In this work, the validity of elastic assumption as it applies to multilayer thin films is studied using the finite element method. The elastic modulus and hardness from the model system are compared to experimental results to show validity of the model. Plastic strain is shown to increase in the multilayer system during the unloading process. Additionally, the indentation-derived modulus of a monolayermore » material shows no dependence on unloading plasticity while the modulus of the multilayer system is dependent on unloading-induced plasticity. Lastly, the cyclic behavior of the multilayer thin film is studied in relation to the influence of unloading-induced plasticity. Furthermore, it is found that several cycles are required to minimize unloading-induced plasticity.« less

Three-dimensional curved grid finite-difference modelling for non-planar rupture dynamics

NASA Astrophysics Data System (ADS)

Zhang, Zhenguo; Zhang, Wei; Chen, Xiaofei

2014-11-01

In this study, we present a new method for simulating the 3-D dynamic rupture process occurring on a non-planar fault. The method is based on the curved-grid finite-difference method (CG-FDM) proposed by Zhang & Chen and Zhang et al. to simulate the propagation of seismic waves in media with arbitrary irregular surface topography. While keeping the advantages of conventional FDM, that is computational efficiency and easy implementation, the CG-FDM also is flexible in modelling the complex fault model by using general curvilinear grids, and thus is able to model the rupture dynamics of a fault with complex geometry, such as oblique dipping fault, non-planar fault, fault with step-over, fault branching, even if irregular topography exists. The accuracy and robustness of this new method have been validated by comparing with the previous results of Day et al., and benchmarks for rupture dynamics simulations. Finally, two simulations of rupture dynamics with complex fault geometry, that is a non-planar fault and a fault rupturing a free surface with topography, are presented. A very interesting phenomenon was observed that topography can weaken the tendency for supershear transition to occur when rupture breaks out at a free surface. Undoubtedly, this new method provides an effective, at least an alternative, tool to simulate the rupture dynamics of a complex non-planar fault, and can be applied to model the rupture dynamics of a real earthquake with complex geometry.

Spontaneous rupture of the ascending aorta.

PubMed

Bin Mahmood, Syed Usman; Ulrich, Andrew; Safdar, Basmah; Geirsson, Arnar; Mangi, Abeel A

2018-02-01

Nontraumatic, spontaneous rupture of the ascending aorta is rare and the etiology is largely unknown. We reviewed seven patients from our institution, with no known aortic disease or hereditary connective tissue disorder that presented with spontaneous ascending aortic rupture from 2012 to 2017. Most patients presented with non-radiating chest pain along with hypertension (71.4%). The mean ascending aortic diameter at rupture was 4.60 ± 0.62 cm. The median door-to-operating room time was 2.58 h, resulting from effective implementation of an aortic emergency protocol. There were no operative mortalities. In patients with ascending aortic rupture, aortic diameter may not always correlate with the risk of rupture. Rapid diagnosis combined with a multidisciplinary approach is vital for the successful management of these high-risk patients. © 2018 Wiley Periodicals, Inc.

MEMS squeezer for the measurement of single cell rupture force, stiffness change, and hysteresis

NASA Astrophysics Data System (ADS)

Barazani, B.; Warnat, S.; Fine, A.; Hubbard, T.

2017-02-01

A MEMS squeezer able to compress single living cells underwater until rupture was designed and tested. The relatively large motion range of the device in aqueous media (~2.5 µm) allows provoking cell disruption while measuring cell mechanical properties before and after membrane rupture. An AC driven electrothermal micro actuator with mechanical amplification pressed single cells against a reference back spring. Deformations of the cell and the reference spring were measured with nanoscale resolution using optical Fourier transform techniques. The motion of the reference spring divided by the cell deformation provides the cell stiffness relative to the reference spring constant. An abrupt change in the cell stiffness and the appearance of cracks indicated the cell wall rupture force was reached. A total of 22 baker’s yeast cells (Saccharomyces cerevisiae) were squeezed with the micro device. The average force necessary to rupture the cell membrane was 0.47  ±  0.1 µN. Before rupture the cells had an average stiffness of 9.3  ±  3.1 N m-1 the post-rupture stiffness dropped to 0.94  ±  0.57 N m-1. Cell hysteresis was also measured: cells squeezed and released before reaching the rupture force showed residual deformations below 100 nm, while cells squeezed past the rupture force and then released showed residual deformations between 490 and 990 nm.

Spontaneous splenic rupture in infectious mononucleosis.

PubMed

Rothwell, S; McAuley, D

2001-09-01

Spontaneous splenic rupture is a rare but life-threatening complication of infectious mononucleosis. Abdominal pain and tachycardia are unusual in uncomplicated infectious mononucleosis and should alert a doctor to the possibility of spontaneous splenic rupture.

Characterization of time-dependent changes in strength and stiffness of Florida base materials : final report, October 2008.

DOT National Transportation Integrated Search

2008-10-01

Resilient modulus and Youngs modulus are parameters increasingly used to fundamentally characterize the behavior : of pavement materials both in the laboratory and in the field. This study documents the small-strain Youngs modulus : and larger-...

Shear Modulus for Nonisotropic, Open-Celled Foams Using a General Elongated Kelvin Foam Model

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.; Ghosn, Louis J.

2008-01-01

An equation for the shear modulus for nonisotropic, open-celled foams in the plane transverse to the elongation (rise) direction is derived using an elongated Kelvin foam model with the most general geometric description. The shear modulus was found to be a function of the unit cell dimensions, the solid material properties, and the cell edge cross-section properties. The shear modulus equation reduces to the relation derived by others for isotropic foams when the unit cell is equiaxed.

Rupture Process During the Mw 8.1 2017 Chiapas Mexico Earthquake: Shallow Intraplate Normal Faulting by Slab Bending

NASA Astrophysics Data System (ADS)

Okuwaki, R.; Yagi, Y.

2017-12-01

A seismic source model for the Mw 8.1 2017 Chiapas, Mexico, earthquake was constructed by kinematic waveform inversion using globally observed teleseismic waveforms, suggesting that the earthquake was a normal-faulting event on a steeply dipping plane, with the major slip concentrated around a relatively shallow depth of 28 km. The modeled rupture evolution showed unilateral, downdip propagation northwestward from the hypocenter, and the downdip width of the main rupture was restricted to less than 30 km below the slab interface, suggesting that the downdip extensional stresses due to the slab bending were the primary cause of the earthquake. The rupture front abruptly decelerated at the northwestern end of the main rupture where it intersected the subducting Tehuantepec Fracture Zone, suggesting that the fracture zone may have inhibited further rupture propagation.

Material contrast does not predict earthquake rupture propagation direction

USGS Publications Warehouse

Harris, R.A.; Day, S.M.

2005-01-01

Earthquakes often occur on faults that juxtapose different rocks. The result is rupture behavior that differs from that of an earthquake occurring on a fault in a homogeneous material. Previous 2D numerical simulations have studied simple cases of earthquake rupture propagation where there is a material contrast across a fault and have come to two different conclusions: 1) earthquake rupture propagation direction can be predicted from the material contrast, and 2) earthquake rupture propagation direction cannot be predicted from the material contrast. In this paper we provide observational evidence from 70 years of earthquakes at Parkfield, CA, and new 3D numerical simulations. Both the observations and the numerical simulations demonstrate that earthquake rupture propagation direction is unlikely to be predictable on the basis of a material contrast. Copyright 2005 by the American Geophysical Union.

Women's expectations and experiences of rupture of membranes and views of the potential use of reagent pads for detecting amniotic fluid.

PubMed

Spiby, Helen; Borrelli, Sara; Hughes, Anita J

2017-12-01

To explore first-time mothers' expectations and experiences regarding rupture of membranes at term and their views on the potential use of reagent pads that detect amniotic fluid. There is little information available on women's experiences of spontaneous rupture of membranes, or interest in using methods to confirm rupture of membranes (e.g. reagent pads). Descriptive qualitative study, using focus groups and telephone interviews with women during pregnancy and after the birth of their first baby. Thematic analysis was undertaken to analyse women's responses. Ethics committee approval was obtained. Twenty-five women participated in the study of whom 13 contributed both during pregnancy and postpartum between October 2015-March 2016. Three overarching themes were identified from the data from women's expectations and experiences: uncertainty in how, when and where membranes may rupture; information which was felt to be limited and confirmation of rupture of membranes. The potential use of reagent pads met with varied responses. Women were interested in having facts and figures regarding rupture of membranes, such as characteristics of liquor; volume and probability of membranes rupturing spontaneously at term. Use of a pad as a means of confirmation was viewed as helpful, although the potential for increasing anxiety was raised. © 2017 John Wiley & Sons Ltd.

Sentinel-1 observation of the 2017 Sangsefid earthquake, northeastern Iran: Rupture of a blind reserve-slip fault near the Eastern Kopeh Dagh

NASA Astrophysics Data System (ADS)

Xu, Guangyu; Xu, Caijun; Wen, Yangmao

2018-04-01

New satellites are now revealing InSAR-based surface deformation within a week after natural hazard events. Quick hazard responses will be more publically accessible and provide information to responding agencies. Here we used Sentinel-1 interferometric synthetic aperture radar (InSAR) data to investigate coseismic deformation associated with the 2017 Sangsefid earthquake, which occurred in the southeast margin of the Kopeh Dagh fault system. The ascending and descending interferograms indicate thrust-dominated slip, with the maximum line-of-sight displacement of 10.5 and 13.7 cm, respectively. The detailed slip-distribution of the 2017 Sangsefid Mw6.1 earthquake inferred from geodetic data is presented here for the first time. Although the InSAR interferograms themselves do not uniquely constrain what the primary slip surface is, we infer that the source fault dips to southwest by analyzing the 2.5 D displacement field decomposed from the InSAR observations. The determined uniform slip fault model shows that the dip angle of the seimogenic fault is approximately 40°, with a strike of 120° except for a narrower fault width than that predicted by the empirical scaling law. We suggest that geometric complexities near the Kopeh Dagh fault system obstruct the rupture propagation, resulting in high slip occurred within a small area and much higher stress drop than global estimates. The InSAR-determined moment is 1.71 × 1018 Nm with a shear modulus of 3.32 × 1010 N/m2, equivalent to Mw 6.12, which is consistent with seismological results. The finite fault model (the west-dipping fault plane) reveals that the peak slip of 0.90 m occurred at a depth of 6.3 km, with substantial slip at a depth of 4-10 km and a near-uniform slip of 0.1 m at a depth of 0-2.5 km. We suggest that the Sangsefid earthquake occurred on an unknown blind reverse fault dipping southwest, which can also be recognised through observing the long-term surface effects due to the existence of the blind fault.

Epidemiology of Achilles tendon ruptures: increasing incidence over a 33-year period.

PubMed

Lantto, I; Heikkinen, J; Flinkkilä, T; Ohtonen, P; Leppilahti, J

2015-02-01

We investigated the epidemiology of total Achilles tendon ruptures and complication rates after operative and nonoperative treatments over a 33-year period in Oulu, Finland. Patients with Achilles tendon ruptures from 1979 to 2011 in Oulu were identified from hospital patient records. Demographic data, treatment method, and complications were collected retrospectively from medical records. Overall and sex- and age-specific incidence rates were calculated with 95% confidence intervals (CIs). The overall incidence per 100,000 person-years increased from 2.1 (95% CI 0.3-7.7) in 1979 to 21.5 (95% CI 14.6-30.6) in 2011. The incidence increased in all age groups. The mean annual increase in incidence was 2.4% (95% CI 1.3-4.7) higher for non-sports-related ruptures than for sports-related ruptures (P = 0.036). The incidence of sports-related ruptures increased during the second 11-year period whereas the incidence of non-sports-related ruptures increased steadily over the entire study period. Infection was four times more common after operative treatment compared with nonoperative treatment, re-rupture rates were similar. The incidence of Achilles tendon ruptures increased in all age groups over a 33-year period. Increases were mainly due to sports-related injuries in the second 11-year period and non-sports-related injuries in the last 11-year period. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

In silico synchronization reveals regulators of nuclear ruptures in lamin A/C deficient model cells

NASA Astrophysics Data System (ADS)

Robijns, J.; Molenberghs, F.; Sieprath, T.; Corne, T. D. J.; Verschuuren, M.; de Vos, W. H.

2016-07-01

The nuclear lamina is a critical regulator of nuclear structure and function. Nuclei from laminopathy patient cells experience repetitive disruptions of the nuclear envelope, causing transient intermingling of nuclear and cytoplasmic components. The exact causes and consequences of these events are not fully understood, but their stochastic occurrence complicates in-depth analyses. To resolve this, we have established a method that enables quantitative investigation of spontaneous nuclear ruptures, based on co-expression of a firmly bound nuclear reference marker and a fluorescent protein that shuttles between the nucleus and cytoplasm during ruptures. Minimally invasive imaging of both reporters, combined with automated tracking and in silico synchronization of individual rupture events, allowed extracting information on rupture frequency and recovery kinetics. Using this approach, we found that rupture frequency correlates inversely with lamin A/C levels, and can be reduced in genome-edited LMNA knockout cells by blocking actomyosin contractility or inhibiting the acetyl-transferase protein NAT10. Nuclear signal recovery followed a kinetic that is co-determined by the severity of the rupture event, and could be prolonged by knockdown of the ESCRT-III complex component CHMP4B. In conclusion, our approach reveals regulators of nuclear rupture induction and repair, which may have critical roles in disease development.

Investigation of cryogenic rupture disc design

NASA Technical Reports Server (NTRS)

Keough, J. B.; Oldland, A. H.

1973-01-01

Rupture disc designs of both the active (command actuated) and passive (pressure ruptured) types were evaluated for performance characteristics at cryogenic temperatures and for capability to operate in a variety of cryogens, including gaseous and liquid fluorine. The test results, coupled with information from literature and industry searches, were used to establish a statement of design criteria and recommended practices for application of rupture discs to cryogenic rocket propellant feed and vent systems.

Factors Controlling Stress Rupture of Fiber-Reinforced Ceramic Composites

NASA Technical Reports Server (NTRS)

DiCarlo, J. A.; Yun, H. M.

1999-01-01

The successful application of fiber-reinforced ceramic matrix composites (CMC) depends strongly on maximizing material rupture life over a wide range of temperatures and applied stresses. The objective of this paper is to examine the various intrinsic and extrinsic factors that control the high-temperature stress rupture of CMC for stresses below and above those required for cracking of the 0 C plies (Regions I and II, respectively). Using creep-rupture results for a variety of ceramic fibers and rupture data for CMC reinforced by these fibers, it is shown that in those cases where the matrix carries little structural load, CMC rupture conditions can be predicted very well from the fiber behavior measured under the appropriate test environment. As such, one can then examine the intrinsic characteristics of the fibers in order to develop design guidelines for selecting fibers and fiber microstructures in order to maximize CMC rupture life. For those cases where the fiber interfacial coatings are unstable in the test environment, CMC lives are generally worse than those predicted by fiber behavior alone. For those cases where the matrix can support structural load, CMC life can even be greater provided matrix creep behavior is properly controlled. Thus the achievement of long CMC rupture life requires understanding and optimizing the behavior of all constituents in the proper manner.

Effect of pore geometry on the compressibility of a confined simple fluid

NASA Astrophysics Data System (ADS)

Dobrzanski, Christopher D.; Maximov, Max A.; Gor, Gennady Y.

2018-02-01

Fluids confined in nanopores exhibit properties different from the properties of the same fluids in bulk; among these properties is the isothermal compressibility or elastic modulus. The modulus of a fluid in nanopores can be extracted from ultrasonic experiments or calculated from molecular simulations. Using Monte Carlo simulations in the grand canonical ensemble, we calculated the modulus for liquid argon at its normal boiling point (87.3 K) adsorbed in model silica pores of two different morphologies and various sizes. For spherical pores, for all the pore sizes (diameters) exceeding 2 nm, we obtained a logarithmic dependence of fluid modulus on the vapor pressure. Calculation of the modulus at saturation showed that the modulus of the fluid in spherical pores is a linear function of the reciprocal pore size. The calculation of the modulus of the fluid in cylindrical pores appeared too scattered to make quantitative conclusions. We performed additional simulations at higher temperature (119.6 K), at which Monte Carlo insertions and removals become more efficient. The results of the simulations at higher temperature confirmed both regularities for cylindrical pores and showed quantitative difference between the fluid moduli in pores of different geometries. Both of the observed regularities for the modulus stem from the Tait-Murnaghan equation applied to the confined fluid. Our results, along with the development of the effective medium theories for nanoporous media, set the groundwork for analysis of the experimentally measured elastic properties of fluid-saturated nanoporous materials.

Metrics for comparing dynamic earthquake rupture simulations

USGS Publications Warehouse

Barall, Michael; Harris, Ruth A.

2014-01-01

Earthquakes are complex events that involve a myriad of interactions among multiple geologic features and processes. One of the tools that is available to assist with their study is computer simulation, particularly dynamic rupture simulation. A dynamic rupture simulation is a numerical model of the physical processes that occur during an earthquake. Starting with the fault geometry, friction constitutive law, initial stress conditions, and assumptions about the condition and response of the near‐fault rocks, a dynamic earthquake rupture simulation calculates the evolution of fault slip and stress over time as part of the elastodynamic numerical solution (Ⓔ see the simulation description in the electronic supplement to this article). The complexity of the computations in a dynamic rupture simulation make it challenging to verify that the computer code is operating as intended, because there are no exact analytic solutions against which these codes’ results can be directly compared. One approach for checking if dynamic rupture computer codes are working satisfactorily is to compare each code’s results with the results of other dynamic rupture codes running the same earthquake simulation benchmark. To perform such a comparison consistently, it is necessary to have quantitative metrics. In this paper, we present a new method for quantitatively comparing the results of dynamic earthquake rupture computer simulation codes.

Treatment of acute Achilles tendon ruptures in Central Finland Central Hospital in 2010-2015.

PubMed

Reito, Aleksi; Logren, Hanna-Liina; Ahonen, Katri; Nurmi, Heikki; Paloneva, Juha

The epidemiology of Achilles tendon ruptures and treatment strategies have undergone a major change in recent years. We investigated the incidence of acute Achilles tendon ruptures, the choice of treatment strategies and treatment implementation. The research material consisted of patients living in the catchment area of Central Finland Hospital District who had been diagnosed with an acute Achilles tendon rupture between 2010 and 2015. The final sample consisted of 266 patients. Conservative treatment was started for 207 patients, and the remaining 59 were referred for surgery. During the study period, the proportion of patients undergoing surgery fell from 41% to 10%. Three patients (1.4%) were referred for surgery during conservative treatment, and 10 patients (4.7%) developed deep vein thrombosis while wearing a cast or an orthosis. Twelve patients (5.8%) sustained a re-rupture after conservative treatment. Two surgically-treated patients (3.5%) sustained a re-rupture, and one patient (1.7%) developed deep vein thrombosis. The strategies for treating acute Achilles tendon ruptures have clearly become more conservative in our hospital. Conservative treatment is safe and rarely fails. However, it is important to bear in mind that surgery still has a role in the treatment of acute Achilles tendon ruptures.

Validity of measurement of shear modulus by ultrasound shear wave elastography in human pennate muscle.

PubMed

Miyamoto, Naokazu; Hirata, Kosuke; Kanehisa, Hiroaki; Yoshitake, Yasuhide

2015-01-01

Ultrasound shear wave elastography is becoming a valuable tool for measuring mechanical properties of individual muscles. Since ultrasound shear wave elastography measures shear modulus along the principal axis of the probe (i.e., along the transverse axis of the imaging plane), the measured shear modulus most accurately represents the mechanical property of the muscle along the fascicle direction when the probe's principal axis is parallel to the fascicle direction in the plane of the ultrasound image. However, it is unclear how the measured shear modulus is affected by the probe angle relative to the fascicle direction in the same plane. The purpose of the present study was therefore to examine whether the angle between the principal axis of the probe and the fascicle direction in the same plane affects the measured shear modulus. Shear modulus in seven specially-designed tissue-mimicking phantoms, and in eleven human in-vivo biceps brachii and medial gastrocnemius were determined by using ultrasound shear wave elastography. The probe was positioned parallel or 20° obliquely to the fascicle across the B-mode images. The reproducibility of shear modulus measurements was high for both parallel and oblique conditions. Although there was a significant effect of the probe angle relative to the fascicle on the shear modulus in human experiment, the magnitude was negligibly small. These findings indicate that the ultrasound shear wave elastography is a valid tool for evaluating the mechanical property of pennate muscles along the fascicle direction.

Aortic regurgitation due to fibrous strand rupture in the fenestrated left coronary cusp of the tricuspid aortic valve.

PubMed

Irisawa, Yusuke; Itatani, Keiichi; Kitamura, Tadashi; Hanayama, Naoji; Oka, Norihiko; Tomoyasu, Takahiro; Inoue, Nobuyuki; Hayashi, Hidenori; Inoue, Takamichi; Miyaji, Kagami

2014-01-01

Fenestration-related massive aortic regurgitation is rare. The underlying mechanism is reported to be rupture of the fenestrated fibrous strand, and most ruptured cords have been reported in the bicuspid valve or in the right coronary cusp of the tricuspid aortic valve. We encountered a rare case of acute aortic regurgitation due to fibrous strand rupture in the fenestrated left coronary cusp. Preoperative echocardiography detected left coronary cusp prolapse, and operative findings revealed rupture of a fibrous strand in the left coronary cusp. For cases such as this, preoperative echocardiography would be useful for appropriate diagnosis.

Controls on Patterns of Repeated Fault Rupture: Examples From the Denali and Bear River Faults

NASA Astrophysics Data System (ADS)

Schwartz, D. P.; Hecker, S.

2013-12-01

A requirement for estimating seismic hazards is assigning magnitudes to earthquake sources. This relies on anticipating rupture length and slip along faults. Fundamental questions include whether lengths of past surface ruptures can be reasonably determined from fault zone characteristics and whether the variability in length and slip during repeated faulting can be constrained. To address these issues, we look at rupture characteristics and their possible controls from examples in very different tectonic settings: the high slip rate (≥15 mm/yr) Denali fault system, Alaska, and the recently activated Bear River normal fault, Wyoming-Utah. The 2002 rupture of the central Denali fault (CDF) is associated with two noteworthy geometric features. First, rupture initiated where the Susitna Glacier thrust fault (SG) intersects the CDF at depth, near the apex of a structurally complex restraining bend along the Denali. Paleoseismic data show that for the past 700 years the timing of large surface ruptures on the Denali fault west of the 2002 rupture has been distinct from those along the CDF. For the past ~6ka the frequency of SG to Denali ruptures has been ~1:12, indicating that this complexity of the 2002 rupture has not been common. Second, rupture propagated off of one strike-slip fault (CDF) onto another (the Totschunda fault, TF), an occurrence that seldom has been observed. LiDAR mapping of the intersection shows direct connectivity of the two faults--the CDF simply branches into both the TF and the eastern Denali fault (EDF). Differences in the timing of earthquakes during the past 700-800 years at sites surrounding this intersection, and estimates of accumulated slip from slip rates, indicate that for the 2002 rupture sufficient strain had accumulated on the TF to favor its failure. In contrast, the penultimate CDF rupture, with the same slip distribution as in 2002, appears to have stopped at or near the branch point, implying that neither the TF nor the EDF was stressed sufficiently to fail at that time. The Bear River fault zone (BRFZ) is a young normal fault along the eastern margin of basin-range extension that appears to have reactivated a ramp in the Laramide-age Darby-Hogsback thrust. The entire Cenozoic history of the BRFZ may consist of only two surface-rupturing events in the late Holocene (one at ~5 ka and the most recent at ~2.5 ka). The 40-km-long fault comprises synthetic and antithetic scarps extending across a zone up to 5 km wide. Remote sensing, including airborne LiDAR, and field studies show that, despite the complexity, the pattern of faulting was similar (in location and amount) for each of the two events and, at the south end, was strongly influenced by the east-west-trending Uinta Arch. Pre-existing structure clearly has exerted a first-order control on moment release on this immature fault. As shown by these examples, data on timing of surface ruptures, coseismic slip, slip rate, and fault geometry can provide a basis to constrain lengths of past and future earthquake ruptures, including possible alternative rupture scenarios. The difficult question for hazard analysis is whether the available data capture the full range of behavior and with what relative frequency do the alternatives occur?

A RETROSPECTIVE ANALYSIS OF ACUTE APPENDICITIS, RUPTURED APPENDICITIS AND THE LEVEL OF LEUKOCYTOSIS IN PAEDIATRIC SURGICAL PATIENTS OF NELSON MANDELA CENTRAL HOSPITAL.

PubMed

Mtimba, L; Dhaffala, A; Molaoa, S Z

2017-06-01

Appendicectomy is the most commonly performed operation worldwide. The diagnosis is predominantly based on clinical findings. Some patients will clinically be unclear if ruptured or acute inflamed appendicitis; the level of white cell count has been used as the predictor for ruptured appendicitis. This was a retrospective chart review of paediatric surgical patients admitted at Nelson Mandela Central Hospital, Mthatha South Africa. A total of 214 patients with a diagnosis of acute appendicitis. Overall, the ruptured appendicitis was 62% and 38% were inflamed appendicitis. Nature of the acute appendicitis: White cell count, Inflamed, Ruptured, Total p-value < 9.9 21 30 51 0.075, 10-14.9 28 54 82 0.0, 15-19.9 17 29 46 0.012, 20-29.9 5 26 31 0.0 > 30 0 4 4. This study has demonstrated that in patients who are diagnosed with acute appendicitis clinically, the normal white cell count does not necessarily rule out ruptured acute appendicitis. But the risks of ruptured acute appendicitis increase with the increase level of white cell count.

Indirect choroidal ruptures: aetiological factors, patterns of ocular damage, and final visual outcome.

PubMed Central

Wood, C M; Richardson, J

1990-01-01

Indirect choroidal ruptures result from blunt ocular trauma and have a pathognomonic fundal appearance. We analysed a group of 30 patients with indirect choroidal ruptures with specific reference to the circumstances of the injury, the pattern of ocular damage, the cause of any visual loss, and the final visual outcome. Using this analysis we deduce a pathogenetic explanation for the characteristic fundus signs in patients with indirect choroidal ruptures. The majority of cases were young males injured during sport or by an assault, a minority were injured at work. Diffuse nonfocal impact injuries due to punches were associated with ruptures concentric with and adjacent to the optic disc. Focal impact injuries, due to projectiles, showed more extensive ocular damage. Seventeen of 30 patients regained 6/12 vision after injury. Injuries due to projectiles and temporally situated ruptures were associated with a poorer visual outcome than others. Macular damage was the commonest cause of visual loss, principally due to pigmentary maculopathy, traumatic inner retinal damage, and choroidal neovascular membranes rather than direct focal damage by the rupture. Images PMID:2337545

Perspective sur les ruptures d’approvisionnement de médicaments en établissement de santé de 2006 à 2010

PubMed Central

Bussières, Jean-François; Chiveri, Andrei; Lebel, Denis

2011-01-01

RÉSUMÉ Contexte: Si les ruptures d’approvisionnement de médicaments font partie de la réalité de la pratique pharmaceutique depuis plusieurs décennies, elles deviennent une préoccupation quotidienne pour les pharmaciens dans les années 2000 et dépassent les frontières de la littérature pharmaceutique. Objectif: L’objectif principal de cette étude était de quantifier le nombre de médicaments en rupture de stock par année et la durée de ces interruptions. L’objectif secondaire visait à décrire le nombre de médicaments en rupture de stock par fabricant et par classe thérapeutique. Méthode: Cette étude descriptive et rétrospective des ruptures d’approvisionnement en médicaments a porté sur l’ensemble des médicaments à contrat pour les hôpitaux des régions administratives de Montréal, de Laval et de l’Estrie, au Québec. Le nombre de ruptures de stocks, le nombre de jours de rupture de stock et leur durée moyenne par année ont été calculés par fabricant et par classe thérapeutique. De plus, la proportion de produits en rupture de stock et la proportion de jours de rupture de stocks ont été déterminées par classe thérapeutique. Les données ont été analysées à l’aide de statistiques descriptives (c.-à-d. somme, moyenne, écart-type, médiane, intervalle). Résultats: Entre le 1er janvier 2006 et le 31 août 2010 (une période de 56 mois), 2400 ruptures de stocks ont été dénombrées pour un total de 258 105 jours de rupture de stocks (durée moyenne de 108 jours, écart-type de 130 jours et intervalle de 5 à 1623 jours). Un total de 70 fabricants étaient impliqués dans la survenue de toutes les ruptures d’approvisionnement de médicaments relevées durant cette période. Cinquante pour cent (50 %) des ruptures de stocks et des jours de rupture de stocks provenaient de quatre fabricants. Les interruptions étudiées touchaient la majorité des classes thérapeutiques de médicaments disponibles sur le marché. Toutefois, 50 % des ruptures de stocks provenaient de trois classes thérapeutiques (médicaments du système nerveux central, agents anti-infectieux et médicaments cardiovasculaires). Conclusion: Il s’agit des premières données canadiennes publiées sur l’étendue des ruptures d’approvisionnement sur le marché hospitalier. L’étude a démontré que les ruptures de stocks touchent la plupart des fabricants et la majorité des classes thérapeutiques. D’autres études sont nécessaires afin d’explorer les causes et les conséquences des ruptures d’approvisionnement en établissements de santé. PMID:22479098

Dynamic rupture modeling with laboratory-derived constitutive relations

USGS Publications Warehouse

Okubo, P.G.

1989-01-01

A laboratory-derived state variable friction constitutive relation is used in the numerical simulation of the dynamic growth of an in-plane or mode II shear crack. According to this formulation, originally presented by J.H. Dieterich, frictional resistance varies with the logarithm of the slip rate and with the logarithm of the frictional state variable as identified by A.L. Ruina. Under conditions of steady sliding, the state variable is proportional to (slip rate)-1. Following suddenly introduced increases in slip rate, the rate and state dependencies combine to produce behavior which resembles slip weakening. When rupture nucleation is artificially forced at fixed rupture velocity, rupture models calculated with the state variable friction in a uniformly distributed initial stress field closely resemble earlier rupture models calculated with a slip weakening fault constitutive relation. Model calculations suggest that dynamic rupture following a state variable friction relation is similar to that following a simpler fault slip weakening law. However, when modeling the full cycle of fault motions, rate-dependent frictional responses included in the state variable formulation are important at low slip rates associated with rupture nucleation. -from Author

Macroscopic Asymmetry of Dynamic Rupture on a Bimaterial Interface With Velocity- Weakening Friction

NASA Astrophysics Data System (ADS)

Ampuero, J.; Ben-Zion, Y.

2006-12-01

Large faults typically separate rocks of different elastic properties. In-plane ruptures on bimaterial interfaces have remarkable dynamic properties that may be relevant to many issues of basic and applied science (e.g., Ben-Zion, 2001). In contrast to slip between similar media, slip along a bimaterial interface generates dynamic changes of normal stress that modify the local fault strength (e.g., Weertman, 1980). One important issue is whether rupture on a bimaterial interface evolves toward a unilateral wrinkle-like pulse in the direction of motion of the compliant medium (the "preferred" direction), or whether it propagates as a symmetric bilateral crack. Some field data suggest that bimaterial interfaces in natural fault zones produce macroscopic rupture asymmetry (Dor et al., 2006; Lewis et al., 2005, 2006); however, this is a subject of ongoing debate. Rubin and Ampuero (2006) performed numerical simulations of bimaterial ruptures under pure slip-weakening friction. They found bilateral crack-like ruptures without significant asymmetry of slip. For ruptures that stopped in low stress areas, there was asymmetry in the final stress distribution, induced by a small scale pulse that detaches from the crack when it stops. This may provide a mechanism for the observed asymmetry of microearthquakes on segments of the San Andreas fault (Rubin and Gillard, 2000). In addition, the results included very prominent asymmetry of slip velocities at the opposite rupture fronts. In calculations with slip-weakening friction the strong asymmetry of slip velocities can not manifest itself into macroscopic rupture asymmetry. However, incorporating in the simulations rate-dependent friction may produce larger stress drop in the preferred direction, leading to macroscopically asymmetric rupture (Ben-Zion, 2006). In this work we study the effect of velocity-weakening friction on rupture along a bimaterial interface, using 2D in-plane simulations with a spectral boundary integral method and a rate-and-state dependent friction law with strong velocity dependence. The law contains slip-weakening or velocity-weakening as limit cases, depending on the length scale in the state evolution law. The steady-state friction coefficient is inversely proportional to slip-rate, mimicking the weakening mechanisms thought to operate on natural faults at high velocities. We examine the behavior of ruptures triggered by a slightly overstressed nucleation zone of size larger than a critical size derived by linear stability analysis. We characterize the range of friction parameters and initial stress values for which ruptures behave as cracks or pulses, decaying or sustained, with subshear or super-shear speeds. All sustained ruptures are initially bilateral. In the range where sub-shear pulse-like rupture is observed, the ruptures develop strong macroscopic asymmetry with continuing propagation along the bimaterial interface. This is manifested by significantly larger seismic potency and propagation distance in the preferred direction, similar to what was found by Shi and Ben-Zion (2006) with strong nucleation phases and slip-weakening friction. The stress asymmetry mechanism described by Rubin and Ampuero (2006) remains in our velocity-weakening simulations as a super-imposed small-scale feature.

UTILIZING RESULTS FROM INSAR TO DEVELOP SEISMIC LOCATION BENCHMARKS AND IMPLICATIONS FOR SEISMIC SOURCE STUDIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. BEGNAUD; ET AL

2000-09-01

Obtaining accurate seismic event locations is one of the most important goals for monitoring detonations of underground nuclear teats. This is a particular challenge at small magnitudes where the number of recording stations may be less than 20. Although many different procedures are being developed to improve seismic location, most procedures suffer from inadequate testing against accurate information about a seismic event. Events with well-defined attributes, such as latitude, longitude, depth and origin time, are commonly referred to as ground truth (GT). Ground truth comes in many forms and with many different levels of accuracy. Interferometric Synthetic Aperture Radar (InSAR)more » can provide independent and accurate information (ground truth) regarding ground surface deformation and/or rupture. Relating surface deformation to seismic events is trivial when events are large and create a significant surface rupture, such as for the M{sub w} = 7.5 event that occurred in the remote northern region of the Tibetan plateau in 1997. The event, which was a vertical strike slip even appeared anomalous in nature due to the lack of large aftershocks and had an associated surface rupture of over 180 km that was identified and modeled using InSAR. The east-west orientation of the fault rupture provides excellent ground truth for latitude, but is of limited use for longitude. However, a secondary rupture occurred 50 km south of the main shock rupture trace that can provide ground truth with accuracy within 5 km. The smaller, 5-km-long secondary rupture presents a challenge for relating the deformation to a seismic event. The rupture is believed to have a thrust mechanism; the dip of the fimdt allows for some separation between the secondary rupture trace and its associated event epicenter, although not as much as is currently observed from catalog locations. Few events within the time period of the InSAR analysis are candidates for the secondary rupture. Of these, we have identified six possible secondary rupture events (mb range = 3.7-4.8, with two magnitudes not reported), based on synthetic tests and residual analysis. All of the candidate events are scattered about the main and secondary rupture. A Joint Hypocenter Determination (JHD) approach applied to the aftershocks using global picks was not able to identify the secondary event. We added regional data and used propagation path corrections to reduce scatter and remove the 20-km bias seen in the main shock location. A&r preliminary analysis using several different velocity models, none of the candidate events proved to relocate on the surface trace of the secondary rupture. However, one event (mb = not reported) moved from a starting distance of {approximately}106 km to a relocated distance of {approximately}28 km from the secondary rupture, the only candidate event to relocate in relative proximity to the secondary rupture.« less

Apparatus for controlling fluid flow in a conduit wall

DOEpatents

Glass, S. Jill; Nicolaysen, Scott D.; Beauchamp, Edwin K.

2003-05-13

A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

Incidence of plantar fascia ruptures following corticosteroid injection.

PubMed

Kim, Chul; Cashdollar, Michael R; Mendicino, Robert W; Catanzariti, Alan R; Fuge, LaDonna

2010-12-01

Plantar fasciitis is commonly treated with corticosteroid injections to decrease pain and inflammation. Therapeutic benefits often vary in terms of efficacy and duration. Rupture of the plantar fascia has been reported as a possible complication following corticosteroid injection. A retrospective chart review of 120 patients who received corticosteroid injection for plantar fasciitis was performed at the authors' institution to determine the incidence of plantar fascia rupture. The plantar fascia rupture was diagnosed clinically and confirmed with magnetic resonance imaging. Various factors were analyzed, including the number of injections, interval between injections, body mass index (BMI), and activity level. Four patients (2.4%) consequently experienced plantar fascia rupture following an average of 2.67 injections. The average BMI of these patients was 38.6 kg/m². The authors conclude that corticosteroid injection therapy appears to be a safe and effective form of nonoperative treatment with minimal complications and a relatively low incident of plantar fascia rupture.

Rupture of abdominal aortic aneurysm: concurrent comparison of outcome of those occurring after endovascular repair versus those occurring without previous treatment in an 11-year single-center experience.

PubMed

May, James; White, Geoffrey H; Stephen, Michael S; Harris, John P

2004-11-01

The purpose of this single-center study was to compare findings at presentation and surgical outcome in patients in whom abdominal aortic aneurysms (AAAs) ruptured after endovascular repair and patients in whom AAAs ruptured before any treatment, over a defined period. From May 1992 to September 2003, 1043 patients underwent elective repair of intact infrarenal AAAs. Endovascular repair was performed in 609 patients, and open repair in 434 patients. Eighteen of 609 patients (3%) who underwent endovascular AAA repair required treatment because of rupture of the aneurysm after a mean of 29 months (group 1). During the same 11-year period, another 91 patients without previous treatment required urgent repair of a ruptured AAA (group 2). Rupture was diagnosed at contrast material-enhanced computed tomography or by presence of extramural extravasation of blood at open repair. Except for a higher incidence of women in group 2, patients in both groups were similar with regard to demographics and clinical characteristics but differed in findings at presentation. Eight patients in group 1 had a known endoleak before AAA rupture, whereas contrast-enhanced computed tomography, performed in 15 patients at presentation, demonstrated an endoleak in all. Hypotension (systolic blood pressure <100 mm Hg) was noted at presentation in 4 of 18 patients (22%) in group 1 and 76 of 91 patients (84%) in group 2. All patients underwent open repair via a transperitoneal approach, except for 4 patients in group 1 and 3 patients in group 2 who underwent endovascular repair of ruptured AAAs. The proportion of patients with hypotension at presentation in group 1 (4 of 18) was significantly less than in group 2 (76 of 91; P < .01). The difference in perioperative (30 day) mortality rate in group 1 (3 of 18; 16.6%) compared with group 2 (49 of 91; 53.8%) was also significant (P < .01). The outcome in group 1 was therefore superior to that in group 2. This study confirms that endovascular AAA repair complicated by endoleak does not prevent rupture. The data suggest, however, that rupture, when it occurs in these circumstances, may not be accompanied by such major hemodynamic changes and high mortality as rupture of an untreated AAA. Further long-term follow-up and analysis in a larger group of patients are required to confirm the apparent intermediate level of protection afforded by failed endovascular repair, which does not prevent rupture but enhances survival after operation to treat rupture, possibly by ameliorating the hemodynamic changes associated with the rupture process.

Nanoindentation mapping of a wood-adhesive bond

NASA Astrophysics Data System (ADS)

Konnerth, J.; Valla, A.; Gindl, W.

2007-08-01

A mapping experiment of a wood phenol-resorcinol-formaldehyde adhesive bond was performed by means of grid nanoindentation. The variability of the modulus of elasticity and the hardness was evaluated for an area of 17 μm by 90 μm. Overall, the modulus of elasticity of the adhesive was clearly lower than the modulus of wood cell walls, whereas the hardness of the adhesive was slightly higher compared to cell walls. A very slight trend of decreasing modulus of elasticity was found with increasing distance from the immediate bond line. However, the trend was superimposed by a high variability of the modulus of elasticity in dependence on the position in the wood cell wall. The unexpectedly high variation of the modulus between 12 and 24 GPa may be explained by the interaction between the helical orientation of the cellulose microfibrils in the S2 layer of the wood cell wall and the geometry of the three-sided Berkovich type indenter pyramid used. Corresponding to the very slight decrease in modulus with increasing distance from the bond line, a similar but clearer trend was found for hardness. Both trends of changing mechanical properties of wood cell walls with varying distance from the bond line are attributed to effects of adhesive penetration into the wood cell wall.

Random field assessment of nanoscopic inhomogeneity of bone

PubMed Central

Dong, X. Neil; Luo, Qing; Sparkman, Daniel M.; Millwater, Harry R.; Wang, Xiaodu

2010-01-01

Bone quality is significantly correlated with the inhomogeneous distribution of material and ultrastructural properties (e.g., modulus and mineralization) of the tissue. Current techniques for quantifying inhomogeneity consist of descriptive statistics such as mean, standard deviation and coefficient of variation. However, these parameters do not describe the spatial variations of bone properties. The objective of this study was to develop a novel statistical method to characterize and quantitatively describe the spatial variation of bone properties at ultrastructural levels. To do so, a random field defined by an exponential covariance function was used to present the spatial uncertainty of elastic modulus by delineating the correlation of the modulus at different locations in bone lamellae. The correlation length, a characteristic parameter of the covariance function, was employed to estimate the fluctuation of the elastic modulus in the random field. Using this approach, two distribution maps of the elastic modulus within bone lamellae were generated using simulation and compared with those obtained experimentally by a combination of atomic force microscopy and nanoindentation techniques. The simulation-generated maps of elastic modulus were in close agreement with the experimental ones, thus validating the random field approach in defining the inhomogeneity of elastic modulus in lamellae of bone. Indeed, generation of such random fields will facilitate multi-scale modeling of bone in more pragmatic details. PMID:20817128

Chorioretinal neovascular membranes complicating contusional eye injuries with indirect choroidal ruptures.

PubMed Central

Wood, C M; Richardson, J

1990-01-01

Chorioretinal neovascular membranes are a recognised but rare cause of late visual loss in eyes suffering contusional injuries. A series of eight cases is presented all with indirect choroidal ruptures involving the perifoveal region. Two main patterns of 'at risk' rupture were noted: a temporally situated rupture passing almost directly through the fovea, and a rupture which curves inferior or superior to the optic disc stopping just short of the fovea. In six of eight cases there was only a partial thickness rupture of the choroid. These neovascular membranes may present at any time after the original injury, either early (within six months of the injury), which could be related to persistence of the normal reparative neovascular response, or late (at least one year after the injury), which are more likely to have resulted from a secondary breakdown of the outer blood-retina barrier. Images PMID:1690025

Critical behavior of modulus of gel

NASA Astrophysics Data System (ADS)

Tokita, Masayuki; Niki, Ryoya; Hikichi, Kunio

1985-09-01

The critical behavior of the shear modulus of casein gel is studied. The shear modulus of casein gel scales with the conductivity exponent in the immediate vicinity of the sol-gel transition point. The asymptotic behavior of the modulus in the region far above the transition point is governed by a different exponent which is much larger than the conductivity exponent. These results are explainable by the crossover behavior of the percolation process. This study shows that the gelation of the casein micelle solution is a realization of the percolation process.

Self-healing slip pulses in dynamic rupture models due to velocity-dependent strength

USGS Publications Warehouse

Beeler, N.M.; Tullis, T.E.

1996-01-01

Seismological observations of short slip duration on faults (short rise time on seismograms) during earthquakes are not consistent with conventional crack models of dynamic rupture and fault slip. In these models, the leading edge of rupture stops only when a strong region is encountered, and slip at an interior point ceases only when waves from the stopped edge of slip propagate back to that point. In contrast, some seismological evidence suggests that the duration of slip is too short for waves to propagate from the nearest edge of the ruptured surface, perhaps even if the distance used is an asperity size instead of the entire rupture dimension. What controls slip duration, if not dimensions of the fault or of asperities? In this study, dynamic earthquake rupture and slip are represented by a propagating shear crack. For all propagating shear cracks, slip velocity is highest near the rupture front, and at a small distance behind the rupture front, the slip velocity decreases. As pointed out by Heaton (1990), if the crack obeys a negative slip-rate-dependent strength relation, the lower slip velocity behind the rupture front will lead to strengthening that further reduces the velocity, and under certain circumstances, healing of slip can occur. The boundary element method of Hamano (1974) is used in a program adapted from Andrews (1985) for numerical simulations of mode II rupture with two different velocity-dependent strength functions. For the first function, after a slip-weakening displacement, the crack follows an exponential velocity-weakening relation. The characteristic velocity V0 of the exponential determines the magnitude of the velocity-dependence at dynamic velocities. The velocity-dependence at high velocity is essentially zero when V0 is small and the resulting slip velocity distribution is similar to slip weakening. If V0 is larger, rupture propagation initially resembles slip-weakening, but spontaneous healing occurs behind the rupture front. The rise time and rupture propagation velocity depend on the choice of constitutive parameters. The second strength function is a natural log velocity-dependent form similar to constitutive laws that fit experimental rock friction data at lower velocities. Slip pulses also arise with this function. For a reasonable choice of constitutive parameters, slip pulses with this function do not propagate at speeds greater than the Raleighwave velocity. The calculated slip pulses are similar in many aspects to seismic observations of short rise time. In all cases of self-healing slip pulses, the residual stress increases with distance behind the trailing edge of the pulse so that the final stress drop is much less than the dynamic stress drop, in agreement with the model of Brune (1976) and some recent seismological observations of rupture.

Investigation of the use of resilient modulus for Louisiana soils in the design of pavements: final report.

DOT National Transportation Integrated Search

1994-06-01

The 1986 AASHTO Guide for the Design of Pavement Structures has adopted the use of resilient modulus (M,) as a fundamental proponent to characterize flexible pavement materials. The resilient modulus is defmed as the ratio of the repeated axial devia...

Blood vessel rupture by cavitation

PubMed Central

Chen, Hong; Brayman, Andrew A.; Bailey, Michael R.

2011-01-01

Cavitation is thought to be one mechanism for vessel rupture during shock wave lithotripsy treatment. However, just how cavitation induces vessel rupture remains unknown. In this work, a high-speed photomicrography system was set up to directly observe the dynamics of bubbles inside blood vessels in ex vivo rat mesenteries. Vascular rupture correlating to observed bubble dynamics were examined by imaging bubble extravasation and dye leakage. The high-speed images show that bubble expansion can cause vessel distention, and bubble collapse can lead to vessel invagination. Liquid jets were also observed to form. Our results suggest that all three mechanisms, vessel distention, invagination and liquid jets, can contribute to vessel rupture. PMID:20680255

Isolated rupture of the gallbladder following blunt abdominal trauma: case report

PubMed Central

Epstein, Marina Gabrielle; da Silva, Dorivaldo Lopes; Elias, Naim Carlos; Sica, Gustavo Tricta Augusto; Fávaro, Murillo de Lima; Ribeiro, Marcelo Augusto Fontenelle

2013-01-01

ABSTRACT Gallbladder rupture following blunt abdominal trauma is a rare event recognized on evaluation and treatment of other visceral injuries during laparotomy. Isolated gallbladder rupture secondary to blunt abdominal trauma is even more uncommon. The clinical presentation of gallbladder injury is variable, resulting in a delay in diagnosis and treatment. We report the case of a patient who suffered an isolated gallbladder rupture due to blunt abdominal trauma. PMID:23843066

Supershear rupture in the 24 May 2013 Mw 6.7 Okhotsk deep earthquake: Additional evidence from regional seismic stations

NASA Astrophysics Data System (ADS)

Zhan, Zhongwen; Shearer, Peter M.; Kanamori, Hiroo

2015-10-01

Zhan et al. (2014a) reported supershear rupture during the Mw 6.7 aftershock of the 2013 Mw 8.3 Sea of Okhotsk deep earthquake, relying heavily on the regional station PET, which played a critical role in constraining the vertical rupture dimension and rupture speed. Here we include five more regional stations and find that the durations of the source time functions derived from these stations are consistent with Zhan et al.'s supershear rupture model. Furthermore, to reduce the nonuniqueness of deconvolution and combine the bandwidths of different stations, we conduct a joint inversion of the six regional stations for a single broadband moment-rate function (MRF). The best fitting MRF, which explains all the regional waveforms well, has a smooth shape without any temporal gaps. The Mw 6.7 Okhotsk deep earthquake is more likely a continuous supershear rupture than a dynamically triggered doublet.

Spontaneous ruptured pheochromocytoma: an unusual case report and literature review.

PubMed

Jee, Ye Seob

2017-09-01

Ruptured pheochromocytoma is a rare disease. Its mortality rate is up to 31%-50%. Proper management of ruptured pheochromocytoma remains unclear. A 44-year-old male patient visited our Emergency Department and presented with abrupt onset of left flank pain. His blood pressure was 190/140 mmHg with purse rate of 130 beats/min. CT scan showed 8.1 × 5.6-cm-sized heterogeneously mass with rupture on the left retroperitoneal space and active bleeding. His symptom of abdominal pain was aggravated. Follow-up laboratory analysis revealed elevated WBC count and decreased hemoglobin 2 hours after admission. Emergency laparotomy was performed. We resected the ruptured left retroperitoneal mass and hemostasis. Pathologic exams revealed adrenal pheochromocytoma with rupture. Although our patient was alive, according to literature review, mortality rate of emergency operation without medical management is higher than elective operation after blood pressure control with either medical or interventional methods such as transcatheter arterial embolization.

Rupture disc

DOEpatents

Newton, Robert G.

1977-01-01

The intermediate heat transport system for a sodium-cooled fast breeder reactor includes a device for rapidly draining the sodium therefrom should a sodium-water reaction occur within the system. This device includes a rupturable member in a drain line in the system and means for cutting a large opening therein and for positively removing the sheared-out portion from the opening cut in the rupturable member. According to the preferred embodiment of the invention the rupturable member includes a solid head seated in the end of the drain line having a rim extending peripherally therearound, the rim being clamped against the end of the drain line by a clamp ring having an interior shearing edge, the bottom of the rupturable member being convex and extending into the drain line. Means are provided to draw the rupturable member away from the drain line against the shearing edge to clear the drain line for outflow of sodium therethrough.

Observations of the rupture development process from source time functions

NASA Astrophysics Data System (ADS)

Renou, Julien; Vallée, Martin

2017-04-01

The mechanisms governing the seismic rupture expansion and leading to earthquakes of very different magnitudes are still under debate. In the cascade model, the rupture starts from a very small patch, which size is undetectable by seismological investigation. Then rupture grows in a self-similar way, implying that no clues about the earthquake magnitude can be found before rupture starts declining. However dependencies between early phases of the rupture process and final magnitude have also been proposed, which can be explained if an earthquake is more likely to be a big one when its start and early development occur in rupture-prone areas. Here, the analysis of the early phases of the seismic rupture is achieved from an observational point of view using the SCARDEC database, a global catalog containing more than 3000 Source Time Functions (STFs) of earthquakes with magnitude larger than 5.7. This dataset is theoretically very suitable to investigate the initial phase, because STFs directly describe the seismic moment rate released over time, giving access to the rupture growth behavior. As several studies already showed that deep earthquakes tend to have a specific signature of short duration with respect to magnitude (implying a quicker rupture growth than superficial events), only shallow events (depths < 70km) are analyzed here. Our method consists in computing the STFs slope, i.e. the seismic moment acceleration, at several prescribed moment rates. In order to ensure that the chosen moment rates intersect the growth phase of the STF, its value must be high enough to avoid the very beginning of the signal -not well constrained in the deconvolution process-, and low enough to avoid the proximity of the peak moment rate. This approach does not use any rupture time information, which is interesting as (1) the exact hypocentral time can be uncertain and (2) the real rupture expansion can be delayed compared to origin time. If any magnitude-dependent signal exists, the average or median value of the slope should vary with the magnitude of the events, despite the intrinsic variability of the STFs. The preliminary results from the SCARDEC dataset seem to only exhibit a weak dependence of the slope with magnitude, in the magnitude domain where the chosen moment rate value crosses most of the STFs onsets. In addition, our results point out that slope values gradually increase with the moment rate. These findings will be discussed in the frame of the existing models of seismic rupture expansion.