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1

Correlation of tensile and shear strengths of metals with their friction properties  

NASA Technical Reports Server (NTRS)

The relation between the theoretical tensile and the shear strengths and the friction properties of metals in contact with diamond, boron nitride, silicon carbide, manganese-zinc ferrite, and the metals themselves in vacuum was investigated. The relationship between the actual shear strength and the friction properties of the metal was also investigated. An estimate of the theoretical uniaxial tensile strength was obtained in terms of the equilibrium surface energy, interplanar spacing of the planes perpendicular to the tensile axis, and the Young's modulus of elasticity. An estimate of the theoretical shear strength for metals was obtained from the shear modulus, the repeat distance of atoms in the direction of shear of the metal and the interplanar spacing of the shear planes. The coefficient of friction for metals was found to be related to the theoretical tensile, theoretical shear, and actual shear strengths of metals. The higher the strength of the metal, the lower the coefficient of friction.

Miyoshi, K.; Buckley, D. H.

1982-01-01

2

Impact tensile properties and strength development mechanism of glass for reinforcement fiber  

NASA Astrophysics Data System (ADS)

In this study, impact tensile properties of E-glass were investigated by fiber bundle testing under a high strain rate. The impact tests were performed employing two types of experiments. One is the tension-type split Hopkinson pressure bar system, and the other is the universal high-speed tensile-testing machine. As the results, it was found that not only the tensile strength but also the fracture strain of E-glass fiber improved with the strain rate. The absorbed strain energy of this material significantly increased. It was also found that the degree of the strain rate dependency of E-glass fibers on the tensile strength was varied according to fiber diameter. As for the strain rate dependency of the glass fiber under tensile loading condition, change of the small crack-propagation behaviour was considered to clarify the development of the fiber strength. The tensile fiber strength was estimated by employing the numerical simulation based on the slow crack-growth model (SCG). Through the parametric study against the coefficient of the crack propagation rate, the numerical estimation value was obtained for the various testing conditions. It was concluded that the slow crack-growth behaviour in the glass fiber was an essential for the increase in the strength of this material.

Kim, T.; Oshima, K.; Kawada, H.

2013-07-01

3

CHARACTERIZATION OF TENSILE STRENGTH OF GLOVEBOX GLOVES  

SciTech Connect

A task was undertaken to compare various properties of different glovebox gloves, having various compositions, for use in gloveboxes at the Savannah River Site (SRS). One aspect of this project was to determine the tensile strength (TS) of the gloves. Longitudinal tensile samples were cut from 15 different gloves and tensile tested. The stress, load, and elongation at failure were determined. All of the gloves that are approved for glovebox use and listed in the glovebox procurement specification met the tensile and elongation requirements. The Viton{reg_sign} compound gloves are not listed in the specification, but exhibited lower tensile strengths than permissible based on the Butyl rubber requirements. Piercan Polyurethane gloves were the thinnest samples and exhibited the highest tensile strength of the materials tested.

Korinko, P.; Chapman, G.

2012-02-29

4

Multivariate analysis approach for correlations between material properties and tablet tensile strength of microcrystalline cellulose.  

PubMed

In this study we applied statistical multivariate analysis techniques to establish correlations between material properties and tablet tensile strength (TS) of microcrystalline cellulose (MCC) with different types and manufacturers. There were sixteen MCC samples included in this analysis described by 22 material parameters. For data analysis, principal component analysis (PCA) was used to model and evaluate the various relationships between the material properties and TS. Furthermore, partial least squares regression (PLS) analysis was performed to quantify the relationships between the material properties and TS and to predict the most influential MCC parameters contributing to the compactibility. The results showed that the moisture content, hygroscopicity and crystallinity did not exhibit significant impact on TS. The turgidity, maximum water uptake, degree of polymerization and molecular weight presented a strong positive influence on TS, while the density property, bulk and tap density, exhibited an obvious negative impact. The present work demonstrated that multivariate data analysis techniques (PCA and PLS) are useful for interpreting complex relations between 22 material properties and the tabletting properties of MCC. Furthermore, the method can be used for material classification. PMID:23016450

Liao, Zhenggen; Zhang, Nan; Zhao, Guowei; Zhang, Jing; Liang, Xinli; Zhong, Shaojin; Wang, Guangfa; Chen, Xulong

2012-09-01

5

Making High-Tensile-Strength Amalgam Components  

NASA Technical Reports Server (NTRS)

Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams, ternary additions to liquid or solid components should be considered as means to impart desired properties to amalgams.

Grugel, Richard

2008-01-01

6

Effects of excipients on the tensile strength, surface properties and free volume of Klucel® free films of pharmaceutical importance  

NASA Astrophysics Data System (ADS)

The physicochemical properties of polymers planned to be applied as mucoadhesive films were studied. Two types of Klucel® hydroxypropylcellulose (LF and MF) were used as film-forming polymers. Hydroxypropylcellulose was incorporated in 2 w/w% with glycerol and xylitol as excipients and lidocaine base as an active ingredient at 5, 10 or 15 w/w% of the mass of the film-forming polymer. The free volume changes of the films were investigated by positron annihilation lifetime spectroscopy, the mechanical properties of the samples were measured with a tensile strength tester and contact angles were determined to assess the surface properties of the films. It was found that the Klucel® MF films had better physicochemical properties than those of the LF films. Klucel® MF as a film-forming polymer with lidocaine base and both excipients at 5 w/w% exhibited physicochemical properties and good workability. The excipients proved to exert strong effects on the physicochemical properties of the tested systems and it is very important to study them intensively in preformulation studies in the pharmaceutical technology in order to utilise their benefits and to avoid any disadvantageous effects.

Gottnek, Mihály; Süvegh, Károly; Pintye-Hódi, Klára; Regdon, Géza

2013-08-01

7

Method and apparatus for determining tensile strength  

DOEpatents

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.

Ratigan, Joe L. (Rapid City, SD)

1984-01-01

8

Tensile Properties of GRCop-84  

NASA Technical Reports Server (NTRS)

This is a chapter in the final report on GRCop-84 for the Reusable Launch Vehicle (RLV) Second Generation/Project Constellation Program. It contains information on the tensile properties of GRCop-84. GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) was produced by extrusion and Hot Isostatic Pressing (HIPing). Some of the extrusions were rolled to plate and sheet while other extrusions were drawn into tubing. The material was further subjected to various heat treatments corresponding to annealing, anticipated typical brazing conditions, an end-of-life condition and various elevated temperature exposures to attempt to improve creep resistance. As anticipated, cold work increased strength while decreasing ductility. Annealing at 600 C (1112 F) and higher temperatures was effective. An exposure for 100 h at 500 C (932 F) resulted in an increase in strength rather than the anticipated decrease. High temperature simulated-braze cycles and thermal exposures lowered the strength of GRCop-84, but the deceases were small compared to precipitation strengthened copper alloys. It was observed that the excess Cr could form large precipitates that lower the reduction in area though it appears a minimum amount is required. Overall, GRCop-84 exhibits good stability of its tensile properties, which makes it an excellent candidate for rocket engine liners and many other high temperature applications.

Ellis, David L.; Loewenthal, William S.; Yun, Hee-Man

2012-01-01

9

49 CFR 230.26 - Tensile strength of shell plates.  

Code of Federal Regulations, 2010 CFR

...DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of steel or wrought-iron shell...

2010-10-01

10

Tensile Properties and Viscoelastic Model of a Polyimide Film  

NASA Astrophysics Data System (ADS)

This paper presents tensile properties of a polyimide thin film used in electronic devices. Tensile tests were performed to determine Young's modulus, proportional limit, yield stress, ultimate tensile strength and elongation of the polyimide film. Effects of strain rate and temperature on the tensile properties were discussed. There was a little effect of strain rate on Young's modulus but proportional limit, yield stress and ultimate tensile strength increased with increasing strain rate. Only elongation decreased with strain rate. Young's modulus, proportional limit, yield stress and ultimate tensile strength decreased with increasing temperature, but elongation increased. Applicability of a viscoelastic model for describing the stress-strain curves of the polyimide film was discussed.

Zhang, Shengde; Mori, Syuhei; Sakane, Masao; Nagasawa, Tadashi; Kobayashi, Kaoru

11

Tensile properties of textile composites  

NASA Technical Reports Server (NTRS)

The importance of textile composite materials in aerospace structural applications has been gaining momentum in recent years. With a view to better understand the suitability of these materials in aerospace applications, an experimental program was undertaken to assess the mechanical properties of these materials. Specifically, the braided textile preforms were infiltrated with suitable polymeric matrices leading to the fabrication of composite test coupons. Evaluation of the tensile properties and the analyses of the results in the form of strength moduli, Poisson's ratio, etc., for the braided composites are presented. Based on our past experience with the textile coupons, the fabrication techniques have been modified (by incorporating glass microballoons in the matrix and/or by stabilizing the braid angle along the length of the specimen with axial fibers) to achieve enhanced mechanical properties of the textile composites. This paper outlines the preliminary experimental results obtained from testing these composites.

Avva, V. Sarma; Sadler, Robert L.; Lyon, Malcolm

1992-01-01

12

Improved molding process ensures plastic parts of higher tensile strength  

NASA Technical Reports Server (NTRS)

Single molding process ensures that plastic parts /of a given mechanical design/ produced from a conventional thermosetting molding compound will have a maximum tensile strength. The process can also be used for other thermosetting compounds to produce parts with improved physical properties.

Heier, W. C.

1968-01-01

13

Data Qualification and Data Summary Report: Intact Rock Properties Data on Tensile Strength, Schmidt Hammer Rebound Hardness, and Rock Triaxial Creep  

SciTech Connect

This report presents a systematic review of the available data in the TDMS that are relevant to the following intact rock properties: rock tensile strength, Schmidt hammer rebound hardness, and rock triaxial creep. Relevant data are compiled from qualified and unqualified sources into the summary DTNs and these DTNs are evaluated for qualification using the method of corroborating data as defined in AP-SIII.2Q, ''Qualification of Unqualified Data''. This report also presents a summary of the compiled information in the form of descriptive statistics and recommended values that will be contained in a Reference Information Base (RIB) item prepared in accordance with AP-SIII.4Q, ''Development, Review, Online Placement, and Maintenance of Individual Reference Information Base Data Items''. The primary purpose of this report is to produce qualified sets of data that include all relevant intact rock tensile strength, Schmidt hammer rebound hardness, and rock triaxial creep testing done over the course of the Yucca Mountain Project (YMP). A second purpose is to provide a qualified summary (i.e., a RIB data item) of the test results using descriptive statistics. The immediate purpose of the report is to support the data needs of repository design; however, the products are designed to be appropriate for general use by the YMP. The appropriateness and limitations, if any, of the data, with respect to the intended use, are addressed in this report.

E.M. Cikanek; R.J. Blakely; T.A. Grant; L.E. Safley

2003-07-29

14

Kevlar 49 fibres: correlation between tensile strength and X-ray diffraction peak positions  

Microsoft Academic Search

The exceptional properties and the consequent extensive applications of Kevlar fibres are well known [1]. Some of the applications utilize the high tensile modulus of the fibres and other applications depend on the high tensile strength. It has been observed that exposure to thermal environments can introduce changes in the tensile characteristics of the fibre [2-4]. In particular, the thermally

M. Shubha; H. V. Parimala; Kalyani Vijayan

1991-01-01

15

Mechanical Strength and Failure Characteristics of Cast Mg-9 pctAl-1 pctZn Alloys Produced by a Heated-Mold Continuous Casting Process: Tensile Properties  

NASA Astrophysics Data System (ADS)

The mechanical properties and failure characteristics of a cast Mg alloy (AZ91: Mg-Al8.9-Zn0.6-Mn0.2) produced by a heated-mold continuous casting process (HMC) are investigated. In a modification of the original HMC process, the cooling of the liquid alloy by direct water spray is carried out in an atmosphere of high-purity argon gas. The HMC-AZ91 alloy exhibits excellent mechanical properties (high strength and high ductility) that are about twice as high as those for the same alloy produced by conventional gravity casting. The increased material strength and ductility of the HMC sample are attributed to nanoscale and microscale microstructural characteristics. The fine grains and tiny spherical eutectic structures ( e.g., Mg17Al12 and Al6Mn) distributed randomly in the matrix of the HMC alloy result in resistance to dislocation movement, leading to high tensile strength. Basal slip on (0001) planes in the relatively organized crystal orientation of the HMC alloy, as well as grain boundary sliding through tiny spherical eutectic structures, results in high ductility. Details of the failure mechanism under static loading in the HMC alloy are also discussed using failure models.

Okayasu, Mitsuhiro; Takeuchi, Shuhei; Ohfuji, Hiroaki

2014-11-01

16

Tensile properties of martensitic stainless steels at elevated temperatures  

Microsoft Academic Search

Tensile properties of quenched and tempered martensitic alloys EP-823, HT-9, and 422 were evaluated at temperatures ranging\\u000a from ambient to 600 C as a function of three different tempering times. The results indicated that the yield strength, ultimate\\u000a tensile strength, and the failure strength were gradually reduced with increasing temperature. The ductility parameters were\\u000a enhanced at elevated temperatures due to

A. K. Roy; S. R Kukatla; B. Yarlagadda; V. N. Potluri; M. Lewis; M. Jones; B. J. O’Toole

2005-01-01

17

Tensile strength and fracture of cemented granular aggregates.  

PubMed

Cemented granular aggregates include a broad class of geomaterials such as sedimentary rocks and some biomaterials such as the wheat endosperm. We present a 3D lattice element method for the simulation of such materials, modeled as a jammed assembly of particles bound together by a matrix partially filling the interstitial space. From extensive simulation data, we analyze the mechanical properties of aggregates subjected to tensile loading as a function of matrix volume fraction and particle-matrix adhesion. We observe a linear elastic behavior followed by a brutal failure along a fracture surface. The effective stiffness before failure increases almost linearly with the matrix volume fraction. We show that the tensile strength of the aggregates increases with both the increasing tensile strength at the particle-matrix interface and decreasing stress concentration as a function of matrix volume fraction. The proportion of broken bonds in the particle phase reveals a range of values of the particle-matrix adhesion and matrix volume fraction for which the cracks bypass the particles and hence no particle damage occurs. This limit is shown to depend on the relative toughness of the particle-matrix interface with respect to the particles. PMID:23160765

Affes, R; Delenne, J-Y; Monerie, Y; Radjaï, F; Topin, V

2012-11-01

18

Dynamic compressive and tensile strengths of spark plasma sintered alumina  

SciTech Connect

Fully dense submicron grain size alumina samples were manufactured from alumina nano-powder using Spark Plasma Sintering and tested in two kinds of VISAR-instrumented planar impact tests. In the first kind, samples were loaded by 1-mm tungsten impactors, accelerated to a velocity of about 1?km/s. These tests were aimed at studying the Hugoniot elastic limit (HEL) of Spark Plasma Sintering (SPS)-processed alumina and the decay, with propagation distance, of the elastic precursor wave. In the tests of the second kind, alumina samples of 3-mm thickness were loaded by 1-mm copper impactors accelerated to 100–1000?m/s. These tests were aimed at studying the dynamic tensile (spall) strength of the alumina specimens. The tensile fracture of the un-alloyed alumina shows a monotonic decline of the spall strength with the amplitude of the loading stress pulse. Analysis of the decay of the elastic precursor wave allowed determining the rate of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced inelastic deformation and to clarify the mechanisms responsible for the deformation. The 1-% addition of Cr{sub 2}O{sub 3} decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.

Girlitsky, I.; Zaretsky, E. [Department of Mechanical Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Kalabukhov, S.; Dariel, M. P.; Frage, N. [Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)

2014-06-28

19

Evaluation of the tensile strength of the human ureter - Preliminary results.  

PubMed

Introduction: Ureteral injuries such as avulsion are directly related to mechanical damage of the ureter. Understanding the tensile strength of this tissue may assist in prevention of iatrogenic injuries. Few published studies have looked at the mechanical properties of the animal ureter, and of those none have determined the tensile strength of the human ureter. Therefore, the purpose of this work was to determine the tensile strength of the human ureter. Materials and Methods: We harvested 11 human proximal ureters from patients who were undergoing nephrectomy for either kidney tumors or non-functioning kidney. The specimens were then cut into multiple circumferentially and longitudinally-oriented tissue strips for tensile testing. Strips were uniaxially stretched to failure in a tensile testing machine. The corresponding force and displacement were recorded. Finally, stress at failure was noted as the tensile strength of the sample. Circumferential tensile strength was also compared in the proximal and distal regions of the specimens. Results: The tensile strength of the ureter in circumferential and longitudinal orientations was found to be 457.52±33.74 Ncm-2 and 902.43±122.08 Ncm-2, respectively (p<0.001). The circumferential strength in the proximal portion of the ureter was 409.89±35.13 Ncm-2 in comparison to 502.89±55.85 Ncm-2 in the distal portion (p=0.08). Conclusions: The circumferential tensile strength of the ureter was found to be significantly lower than the longitudinal strength. Circumferential tensile strength was also lower with more proximal parts of the ureter. This information may be important for the design of "intelligent" devices and simulators in order to prevent complications. PMID:25222851

Shilo, Yaniv; Pichamuthu, Joseph E; Averch, Timothy D; Vorp, David A

2014-09-15

20

Residual Stress Distribution of 600MPa Grade High Tensile Strength Steel Pipe Using Welding fe Simulation  

NASA Astrophysics Data System (ADS)

This paper aims to determine the residual stress distribution of 600MPa grade high tensile strength steel pipe (STKT590) by girth welding. Welding FE simulation is achieved considering temperature dependent physical constants and mechanical properties, obtained by the temperature elevated tensile tests. Comparative analyses clarify the characteristics of residual stress profile near weld joint of STKT590 pipe.

Chang, Kyong-Ho; Jang, Gab-Chul

2011-06-01

21

Nanostructured high-strength molybdenum alloys with unprecedented tensile ductility  

NASA Astrophysics Data System (ADS)

The high-temperature stability and mechanical properties of refractory molybdenum alloys are highly desirable for a wide range of critical applications. However, a long-standing problem for these alloys is that they suffer from low ductility and limited formability. Here we report a nanostructuring strategy that achieves Mo alloys with yield strength over 800 MPa and tensile elongation as large as ~ 40% at room temperature. The processing route involves a molecular-level liquid-liquid mixing/doping technique that leads to an optimal microstructure of submicrometre grains with nanometric oxide particles uniformly distributed in the grain interior. Our approach can be readily adapted to large-scale industrial production of ductile Mo alloys that can be extensively processed and shaped at low temperatures. The architecture engineered into such multicomponent alloys offers a general pathway for manufacturing dispersion-strengthened materials with both high strength and ductility.

Liu, G.; Zhang, G. J.; Jiang, F.; Ding, X. D.; Sun, Y. J.; Sun, J.; Ma, E.

2013-04-01

22

Nanostructured high-strength molybdenum alloys with unprecedented tensile ductility.  

PubMed

The high-temperature stability and mechanical properties of refractory molybdenum alloys are highly desirable for a wide range of critical applications. However, a long-standing problem for these alloys is that they suffer from low ductility and limited formability. Here we report a nanostructuring strategy that achieves Mo alloys with yield strength over 800 MPa and tensile elongation as large as ~ 40% at room temperature. The processing route involves a molecular-level liquid-liquid mixing/doping technique that leads to an optimal microstructure of submicrometre grains with nanometric oxide particles uniformly distributed in the grain interior. Our approach can be readily adapted to large-scale industrial production of ductile Mo alloys that can be extensively processed and shaped at low temperatures. The architecture engineered into such multicomponent alloys offers a general pathway for manufacturing dispersion-strengthened materials with both high strength and ductility. PMID:23353630

Liu, G; Zhang, G J; Jiang, F; Ding, X D; Sun, Y J; Sun, J; Ma, E

2013-04-01

23

Silicon nitride having a high tensile strength  

DOEpatents

A silicon nitride ceramic comprising: a) inclusions no greater than 25 microns in length, b) agglomerates no greater than 20 microns in diameter, and c) a surface finish of less than about 8 microinches, said ceramic having a four-point flexural strength of at least about 900 MPa.

Pujari, Vimal K. (Northboro, MA); Tracey, Dennis M. (Medfield, MA); Foley, Michael R. (Oxford, MA); Paille, Norman I. (Oxford, MA); Pelletier, Paul J. (Millbury, MA); Sales, Lenny C. (Grafton, MA); Willkens, Craig A. (Sterling, MA); Yeckley, Russell L. (Oakham, MA)

1996-01-01

24

Tensile properties of titanium electrolytically charged with hydrogen  

NASA Technical Reports Server (NTRS)

Yield strength, ultimate tensile strength, and elongation were studied for annealed titanium electrolytically charged with hydrogen. The hydrogen was present as a surface hydride layer. These tensile properties were generally lower for uncharged titanium than for titanium with a continuous surface hydride; they were greater for uncharged titanium than for titanium with an assumed discontinuous surface hydride. We suggest that the interface between titanium and titanium hydride is weak. And the hydride does not necessarily impair strength and ductility of annealed titanium. The possibility that oxygen and/or nitrogen can embrittle titanium hydride is discussed.

Smith, R. J.; Otterson, D. A.

1971-01-01

25

Influence of mix proportions and curing conditions on tensile splitting strength of high strength concretes  

Microsoft Academic Search

The effect of the composition of high strength concretes with low water to binder ratio and silica fume on the development\\u000a of splitting tensile strength was studied. A statistical approach was employed to develop formulation which could adequately\\u000a describe the relations between splitting tensile strength and the concrete composition, when cured in two different regimes:\\u000a water curing at 20°C and

K. Kovler; I. Schamban; S. Igarashi; A. Bentur

1999-01-01

26

An investigation into geometry and microstructural effects upon the ultimate tensile strengths of butt welds  

NASA Technical Reports Server (NTRS)

A mathematical theory was evaluated empirically. This theory predicts weld ultimate tensile strength based on material properties and fusion line angles, mismatch, peaking, and weld widths. Welds were made on 1/4 and 1/2 in. aluminum 2219-T87, their geometries were measured, they were tensile tested, and these results were compared to theoretical predictions. Statistical analysis of results was performed to evaluate correlation of theory to results for many different categories of weld geometries.

Gordon, Stephen S.

1992-01-01

27

Characterizing Curing-Cement Slurries by Permeability, Tensile Strength,  

E-print Network

Characterizing Curing-Cement Slurries by Permeability, Tensile Strength, and Shrinkage K.R. Backe oilwell cements. The results show that the curing characteristics are a function of temperature and that there is a correlation between shrinkage and cement content. The paper also introduces a new mechanism for gas migration

Backe, Knut

28

Tensile strength of butt-joined epoxy-aluminum plates  

Microsoft Academic Search

Tensile tests conducted on butt joined epoxy-aluminum plates containing single cracks along the bond surfaces showed that there exists a characteristic crack length below which the fracture strength of the composite is mainly influenced by the stress concentrations at the bond edges. For specimens with cracks longer than the characteristic length the fracture of the composite is entirely controlled by

T. T. Wang; T. K. kwei; H. M. Zupko

1970-01-01

29

Practical Estimates of Tensile Strength and Hoek-Brown Strength Parameter m i of Brittle Rocks  

Microsoft Academic Search

By applying the Griffith stress criterion of brittle failure, one can find that the uniaxial compressive strength (sigmac) of rocks is eight times the value of the uniaxial tensile strength (sigmat). The Griffith strength ratio is smaller than what is normally measured for rocks, even with the consideration of crack closure. The reason is that Griffith's theories address only the

M. Cai

2010-01-01

30

Influence of surface defects on the tensile strength of carbon fibers  

NASA Astrophysics Data System (ADS)

The mechanical properties of carbon fibers, especially their tensile properties, are affected by internal and surface defects. In order to asses in what extent the generation of surface defects can result in a loss of the mechanical properties, non-surface treated carbon fibers were oxidized with three different surface treatment processes: electro-chemical oxidation, oxidation in nitric acid, and oxidation in oxygen plasma. Different surface topographies and surface chemistries were obtained, as well as different types and densities of surface defects. The density of surface defects was measured with both a physical approach (Raman spectroscopy) and a chemical approach (Active Surface Area). The tensile properties were evaluated by determining the Weibull modulus and the scale parameter of each reference, after measuring the tensile strength for four different gauge lengths. A relationship between the tensile properties and the nature and density of surface defects was noticed, as large defects largely control the value of the tensile strength. When optimized, some oxidation surface treatment processes can generate surface functional groups as well as an increase of the mechanical properties of the fibers, because of the removal of the contamination layer of pyrolytic carbon generated during the carbonization of the polyacrylonitrile precursor. Oxidation in oxygen plasma revealed to be a promising technology for alternative surface treatment processes, as high levels of functionalization were achieved and a slight improvement of the mechanical properties was obtained too.

Vautard, F.; Dentzer, J.; Nardin, M.; Schultz, J.; Defoort, B.

2014-12-01

31

Predictions of tensile strength of binary tablets using linear and power law mixing rules.  

PubMed

There has recently been an increased interest in predicting the tensile strength of binary tablets from the properties of the individual components. In this paper, measurements are reported for tensile strength of tablets compressed from single-component and binary powder mixtures of lactose with microcrystalline cellulose (MCC), and lactose with two types of silicified microcrystalline cellulose (SMCC and SMCC-HD), which are different in compressibility. Measurements show the tensile strength increases with the relative density for single powders, and both with the relative density and the mass fraction of cellulose in the mixtures. It was also observed, for binary mixtures compacted at 50 and 150 MPa, that there was a slight variation in porosity with the mass fraction of celluloses. The predictions of the tensile strength of binary tablets from the characteristics of the single-components was analysed with the extended Ryshkewitch-Duckworth model by assuming both linear and power law mixing rules for the determination of the parameters "tensile strength at zero porosity and bonding capacity constant". As consequence, four models were analysed and compared with measurements using criteria based on the standard deviation from the mean values. Results showed a good prediction using a linear mixing rule combined with the power law. However, as the predictions of these models depend on the powders and the porosity range for the characterization of single-components, none of them can be systematically considered as being the best to predict binary behaviour from data for individual powders. PMID:17097245

Michrafy, A; Michrafy, M; Kadiri, M S; Dodds, J A

2007-03-21

32

The Effect of Reprocessing on the Tensile Properties of Composites  

NASA Astrophysics Data System (ADS)

In this study, waste cotton fabric reinforced polymer matrix composite material has been manufactured by a custom made recycling extruder. Composites with different reinforcement ratios as 12,5%wt ( 12,5%wtRPE ) and 25%wt ( 25%wtRPE ) were tested for their mechanical properties such as tensile strength and young's modulus. The material was then granulated down to the size enough to be used in the extrusion process in order to observe the effects of reprocessing. Reprocessing leads to improve Tensile Strength of composite materials and slows down the reduction of tensile strength of polyethylene. It was observed that composite materials were highly affected by the fiber orientation and acts as anisotropic material under the load.

Bodur, Mehmet Safa; Bakkal, Mustafa; Berkalp, Omer Berk; Sadikoglu, Telem Gok

2011-01-01

33

Practical Estimates of Tensile Strength and Hoek-Brown Strength Parameter m i of Brittle Rocks  

NASA Astrophysics Data System (ADS)

By applying the Griffith stress criterion of brittle failure, one can find that the uniaxial compressive strength (?c) of rocks is eight times the value of the uniaxial tensile strength (?t). The Griffith strength ratio is smaller than what is normally measured for rocks, even with the consideration of crack closure. The reason is that Griffith’s theories address only the initiation of failure. Under tensile conditions, the crack propagation is unstable so that the tensile crack propagation stress (?cd)t and the peak tensile strength ?t are almost identical to the tensile crack initiation stress (?ci)t. On the other hand, the crack growth after crack initiation is stable under a predominantly compressive condition. Additional loading is required in compression to bring the stress from the crack initiation stress ?ci to the peak strength ?c. It is proposed to estimate the tensile strength of strong brittle rocks from the strength ratio of R = {{?_{text{c}} }/{left| {?_{text{t} } right|}}} = 8{{?_{text{c}} }/{?_{text{ci} }}}. The term {{?_{text{c}} }/{?_{text{ci} }}} accounts for the difference of crack growth or propagation in tension and compression in uniaxial compression tests. {{?c }/{?_{ci }}} depends on rock heterogeneity and is larger for coarse grained rocks than for fine grained rocks. ?ci can be obtained from volumetric strain measurement or acoustic emission (AE) monitoring. With the strength ratio R determined, the tensile strength can be indirectly obtained from left| {?_{text{t}} } right| = {{?_{text{c}} }/R} = {{?_{text{ci}} }/8}. It is found that the predicted tensile strengths using this method are in good agreement with test data. Finally, a practical estimate of the Hoek-Brown strength parameter m i is presented and a bi-segmental or multi-segmental representation of the Hoek-Brown strength envelope is suggested for some brittle rocks. In this fashion, the rock strength parameters like ?t and m i, which require specialty tests such as direct tensile (or Brazilian) and triaxial compression tests for their determination, can be reasonably estimated from uniaxial compression tests.

Cai, M.

2010-03-01

34

Morphogenesis of Plasmodium zoites is uncoupled from tensile strength  

PubMed Central

A shared feature of the motile stages (zoites) of malaria parasites is a cortical cytoskeletal structure termed subpellicular network (SPN), thought to define and maintain cell shape. Plasmodium alveolins comprise structural components of the SPN, and alveolin gene knockout causes morphological abnormalities that coincide with markedly reduced tensile strength of the affected zoites, indicating the alveolins are prime cell shape determinants. Here, we characterize a novel SPN protein of Plasmodium berghei ookinetes and sporozoites named G2 (glycine at position 2), which is structurally unrelated to alveolins. G2 knockout abolishes parasite transmission and causes zoite malformations and motility defects similar to those observed in alveolin null mutants. Unlike alveolins, however, G2 contributes little to tensile strength, arguing against a cause-effect relationship between tensile strength and cell shape. We also show that G2 null mutant sporozoites display an abnormal arrangement of their subpellicular microtubules. These results provide important new understanding of the factors that determine zoite morphogenesis, as well as the potential roles of the cortical cytoskeleton in gliding motility. PMID:23773015

Tremp, Annie Z; Carter, Victoria; Saeed, Sadia; Dessens, Johannes T

2013-01-01

35

Distribution of tensile property and microstructure in friction stir weld of 6063 aluminum  

Microsoft Academic Search

Dominant microstructural factors governing the global tensile properties of a friction-stir-welded joint of 6063 aluminum\\u000a were examined by estimating distribution of local tensile properties corresponding to local microstructure and hardness. Yield\\u000a and ultimate tensile strengths of the as-welded weld were significantly lower than those of the base material. Postweld aging\\u000a and postweld solution heat-treatment and aging (SHTA) restored the strengths

Yutaka S. Sato; Hiroyuki Kokawa

2001-01-01

36

A novel indirect tensile test method to measure the biaxial tensile strength of concretes and other quasibrittle materials  

SciTech Connect

A novel indirect tensile test method, the biaxial flexure test (BFT) method, has been developed to measure the biaxial tensile strength of concretes. The classical modulus of rupture (MOR) test has been generalized to three dimensions. In this method, we use a circular plate as the new test specimen. This plate is supported by an annular ring. We apply an external load to this specimen through a circular edge. The centers of the specimen, the loading device and the support are identical. The biaxial tensile strength measured by this new method is about 19% greater than the uniaxial tensile strength obtained from the classical modulus of rupture test as reported by other researchers. However, at the same time, we also found that the stochastic deviation of the biaxial tensile strength is about 63% greater than the uniaxial strength.

Zi, Goangseup [Department of Civil, Environmental and Architectural Engineering, Korea, University, 5 Ga 1, An-Am Dong, Sung-Buk Gu, Seoul, 136-701 (Korea, Republic of)], E-mail: g-zi@korea.ac.kr; Oh, Hongseob [Department of Civil Engineering, Jinju National University, 150 Chilam Dong, Jinju, Kyongnam, 660-758 (Korea, Republic of); Park, Sun-Kyu [Department of Civil Engineering, Sungkyunkwan University, 300 Cheoncheon Dong, Jangan Gu, Suwon, Gyeonggi, 440-746 (Korea, Republic of)

2008-06-15

37

Tensile strength of bilayered ceramics and corresponding glass veneers  

PubMed Central

PURPOSE To investigate the microtensile bond strength between two all-ceramic systems; lithium disilicate glass ceramic and zirconia core ceramics bonded with their corresponding glass veneers. MATERIALS AND METHODS Blocks of core ceramics (IPS e.max® Press and Lava™ Frame) were fabricated and veneered with their corresponding glass veneers. The bilayered blocks were cut into microbars; 8 mm in length and 1 mm2 in cross-sectional area (n = 30/group). Additionally, monolithic microbars of these two veneers (IPS e.max® Ceram and Lava™ Ceram; n = 30/group) were also prepared. The obtained microbars were tested in tension until fracture, and the fracture surfaces of the microbars were examined with fluorescent black light and scanning electron microscope (SEM) to identify the mode of failure. One-way ANOVA and the Dunnett's T3 test were performed to determine significant differences of the mean microtensile bond strength at a significance level of 0.05. RESULTS The mean microtensile bond strength of IPS e.max® Press/IPS e.max® Ceram (43.40 ± 5.51 MPa) was significantly greater than that of Lava™ Frame/Lava™ Ceram (31.71 ± 7.03 MPa)(P<.001). Fluorescent black light and SEM analysis showed that most of the tested microbars failed cohesively in the veneer layer. Furthermore, the bond strength of Lava™ Frame/Lava™ Ceram was comparable to the tensile strength of monolithic glass veneer of Lava™ Ceram, while the bond strength of bilayered IPS e.max® Press/IPS e.max® Ceram was significantly greater than tensile strength of monolithic IPS e.max® Ceram. CONCLUSION Because fracture site occurred mostly in the glass veneer and most failures were away from the interfacial zone, microtensile bond test may not be a suitable test for bonding integrity. Fracture mechanics approach such as fracture toughness of the interface may be more appropriate to represent the bonding quality between two materials. PMID:25006377

Champirat, Tharee; Jirajariyavej, Bundhit

2014-01-01

38

Practical Estimates of Tensile Strength and Hoek–Brown Strength Parameter m i of Brittle Rocks  

Microsoft Academic Search

By applying the Griffith stress criterion of brittle failure, one can find that the uniaxial compressive strength (?c) of rocks is eight times the value of the uniaxial tensile strength (?t). The Griffith strength ratio is smaller than what is normally measured for rocks, even with the consideration of crack closure.\\u000a The reason is that Griffith’s theories address only the

M. Cai

2010-01-01

39

Scale effects on the transverse tensile strength of graphite epoxy composites  

NASA Technical Reports Server (NTRS)

The influence of material volume on the transverse tensile strength of AS4/3501-6 graphite epoxy composites was investigated. Tensile tests of 90 degree laminates with 3 different widths and 5 different thicknesses were conducted. A finite element analysis was performed to determine the influence of the grip on the stress distribution in the coupons and explain the tendency for the distribution of failure locations to be skewed toward the grip. Specimens were instrumented with strain gages and extensometers to insure good alignment and to measure failure strains. Data indicated that matrix dominated strength properties varied with the volume of material that was stressed, with the strength decreasing as volume increased. Transverse strength data were used in a volumetric scaling law based on Weibull statistics to predict the strength of 90 degree laminates loaded in three point bending. Comparisons were also made between transverse strength measurements and out-of-plane interlaminar tensile strength measurements from curved beam bending tests. The significance of observed scale effects on the use of tests for material screening, quality assurance, and design allowables is discussed.

Obrien, T. Kevin; Salpekar, Satish A.

1992-01-01

40

Through-the-thickness tensile strength of textile composites  

NASA Technical Reports Server (NTRS)

A series of tests was run to characterize the through-the-thickness tensile strength for a variety of composites that included 2D and 3D braids, 2D and 3D weaves, and prepreg tapes. A new test method based on a curved beam was evaluated. The through-the-thickness deformations were characterized using moire interferometry. Failures were significantly different between the 2D and 3D materials. The 2D materials delaminated between layers due to out-of-plane tensile stresses. The strength of the 2D textile composites did not increase relative to the tapes. The 3D materials failed due to the formation of radial cracks caused by high circumferential stresses along the inner radius. A circumferential crack similar to the 2D materials produced the final failure. Final failure in the 3D materials occurred at a lower bending moment than in other materials. The early failures were caused by radial crack formation rather than low through-the-thickness strength.

Jackson, Wade C.; Ifju, Peter G.

1994-01-01

41

Size effect on flexural, splitting tensile, and torsional strengths of high-strength concrete  

SciTech Connect

This paper presents the results of an investigation into the size effect on flexural, splitting tensile, and torsional strengths of high-strength concrete (HSC) with normal aggregate (crushed limestone) and lightweight aggregate (sintered fly ash). The Bazant`s size effect law gives a very good fit to the flexural strengths of both normal and lightweight aggregate HSC measured from beams of different sizes. As observed in the size effect curve, the fracture behavior of the lightweight HSC seems more brittle than that of the normal HSC. Linear elastic fracture mechanics may still be less applicable to HSC in the normal size range than nonlinear fracture mechanics. A reverse size effect is observed in the prism splitting tensile strengths of both normal and light-weight HSC and possible mechanisms of the reverse size effect are discussed. The torsional strength of the lightweight HSC appears to have a stronger size dependency than that of the normal HSC.

Zhou, F.P.; Balendran, R.V.; Jeary, A.P. [City Univ. of Hong Kong (Hong Kong). Dept. of Building and Construction] [City Univ. of Hong Kong (Hong Kong). Dept. of Building and Construction

1998-12-01

42

METHOD FOR DETERMINING ULTIMATE TENSILE STRENGTH OF CONCRETE ANCHORAGE DEVICES  

E-print Network

Prior to handling test materials, performing equipment setups, and/or conducting this method, testers are required to read “SAFETY AND HEALTH ” in Section H of this method. It is the responsibility of the user of this method to consult and use departmental safety and health practices and determine the applicability of regulatory limitations before any testing is performed. A. OVERVIEW This method describes the test procedure to be followed in determining the tensile strength of various concrete anchorage devices, including cast-in-place concrete inserts, undercut anchors, and threaded bars and rebar dowels post-bonded with cartridge epoxy, portland cement grout, magnesium phosphate concrete, or other approved bonding materials.

unknown authors

43

Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.  

PubMed

The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks. PMID:23858281

Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

2012-06-01

44

Development of Manila Hemp Fiber Epoxy Composite with High Tensile Properties Through Handpicking Fiber Fragments  

NASA Astrophysics Data System (ADS)

Manila hemp fibers are separated to several sequent fragments from single fiber. The tensile strength of each fiber fragments and their epoxy composite are measured, followed by scanning electronic microscopic (SEM) analysis. The results show that the tensile strength of fiber fragments is almost constant along fiber. For composite, the tensile strength first increases and then decreases at the position near to root. The Young's modulus presents increasing with location from root to top for fiber and composite. Microstructure analysis indicates that the difference of tensile properties between fiber fragments derive from the difference of fiber diameter.

Liu, Ke; Takagi, Hitoshi; Yang, Zhimao

45

Tensile properties of nitrile elastomers  

E-print Network

Page ABSTRACT ACKNOWLEDGMENTS TABLE OF CONTENTS lv LIST OF FIGURES LIST OF TABLES l. INTRODUCTION 1. 1 Polymers, Rubbers, and Elastomers . 1. 2 Elastomers in the Oil Industry 1. 3 Material Testing of Elastomers 1. 4 Finite Element Modeling... 25 Effect on Material Properties 29 Figure 2. 2 - Removal of Rubber Compound from an Internal Mixer 31 Figure 2. 3 - Addition of Rubber Compound to a Two Roll Mill 32 Figure 2. 4 ? Working of Rubber Compound on a Two Roll Mill 33 Figure 2. 5...

Fairbrother, Debora Ann

1992-01-01

46

Tensile strength and the mining of black holes.  

PubMed

There are a number of important thought experiments that involve raising and lowering boxes full of radiation in the vicinity of black hole horizons. This Letter looks at the limitations placed on these thought experiments by the null energy condition, which imposes a fundamental bound on the tensile-strength-to-weight ratio of the materials involved, makes it impossible to build a box near the horizon that is wider than a single wavelength of the Hawking quanta, and puts a severe constraint on the operation of "space elevators" near black holes. In particular, it is shown that proposals for mining black holes by lowering boxes near the horizon, collecting some Hawking radiation, and dragging it out to infinity cannot proceed nearly as rapidly as has previously been claimed. As a consequence of this limitation, the boxes and all the moving parts are superfluous and black holes can be destroyed equally rapidly by threading the horizon with strings. PMID:24313473

Brown, Adam R

2013-11-22

47

Quantifying the tensile strength of microbial mats grown over noncohesive sediments.  

PubMed

Biofilms in marine and fluvial environments can comprise strong bacterial and diatom mats covering large areas of the bed and act to bind sediments. In this case the bed material becomes highly resistant to shear stresses applied by the overlying fluid motion and detachment, when it does occur, is manifest in patches of biofilm of the order cm(2) being entrained into the flow. This article is the first to report tensile test data specific to the centimeter scale using moist biofilm/sediment composite materials; the strain (?)-stress (?) relationships permit quantification of the elasticity (Young's modulus, E) and cohesive strength of each specimen. Specifically, we compare the mechanical strength of cyanobacterial biofilm-only samples to that of biofilm cultured over sediment samples (glass beads or natural sands of d ~ 1 mm) for up to 8 weeks. The range of tensile strength (1,288-3,283 Pa) for composite materials was up to three times higher than previous tensile tests conducted at smaller scale on mixed culture biofilm [Ohashi et al. (1999) Water Sci Technol 39:261-268], yet of similar range to cohesive strength values recorded on return activated sludge flocs [RAS; Poppele and Hozalski (2003) J Microbiol Methods 55:607-615]. Composite materials were 3-6 times weaker than biofilm-only samples, indicating that adhesion to sediment grains is weaker than cohesion within the biofilm. Furthermore, in order to relate the tensile test results to the more common in-situ failure of bio-mats due to shear flow, controlled erosion experiments were conducted in a hydraulic flume with live fluid flow. Here, the fluid shear stress causing erosion was 3 orders of magnitude lower than tensile stress; this highlights both the problem of interpreting material properties measured ex-situ and the need for a better mechanistic model of bio-mat detachment. PMID:22170239

Vignaga, E; Haynes, H; Sloan, W T

2012-05-01

48

DETERMINATION OF THE TENSILE STRENGTH OF MAGNESIUM PHOSPHATE CEMENTS CONTAINING DIFFERENT METALS USING THE BRAZILIAN TEST  

E-print Network

Surface treatment processes like electrolytic or electroless plating provide coatings to metallic parts improving some of their properties like corrosion resistance, wear resistance and appearance [1]. Such processes use baths containing high concentration of heavy metals like chromium, nickel, zinc, etc. When exhausted, the bath becomes a hazardous waste which has to be properly managed. An option for the valorization of the waste is manufacturing of magnesium phosphate cement parts that may be cast in order to obtain road walls or as a base for roads [2]. The stabilized waste may also be disposed at a landfill. In order to know the performance of the material, the strength of the specimens is usually determined. Pastes containing different heavy metals (cadmium, copper, chromium, nickel, lead and zinc) were prepared with a metal concentration of 25000 ppm, a water-to-solid ratio(W/S) of 0.3, 0.4, 0.5 (0.4, 0.5 and 0.6 for Cr) and a magnesium oxide content of 50 % in weight of the total solid. They were allowed to solidify and after 10 months of curing. After that, disks were cut and they were subjected to an indirect tensile strength test (Brazilian test or splitting test) [3]. In general, tensile strength decreased with increasing water content as expected. The specimens prepared with a water-to-solid ratio (W/S) of 0.3 showed relatively high tensile strength values.

Irene Buj Corral; Josep Torras Grané; Miquel Rovira Boixaderas; Joan De Pablo

49

Improved tensile strength of glycerol-plasticized gluten bioplastic containing hydrophobic liquids.  

PubMed

The aim of the present work has been to study the influence of hydrophobic liquids on the morphology and the properties of thermo-molded plastics based on glycerol-plasticized wheat gluten (WG). While the total amount of castor oil and glycerol was remained constant at 30 wt%, castor oil with various proportions with respect to glycerol was incorporated with WG by mixing at room temperature and the resultant mixtures were thermo-molded at 120 degrees C to prepare sheet samples. Moisture absorption, morphology, dynamic mechanical properties, and tensile properties (Young's modulus, tensile strength and elongation at break) of the plastics were evaluated. Experimental results showed that the physical properties of WG plastic were closely related to glycerol to castor oil ratio. Increasing in castor oil content reduces the moisture absorption markedly, which is accompanied with a significant improvement in tensile strength and Young's modulus. These observations were further confirmed in 24 wt% glycerol-plasticized WG plastics containing 6 wt% silicone oil or polydimethylsiloxane (PDMS) liquid rubber. PMID:18337091

Song, Yihu; Zheng, Qiang

2008-11-01

50

Evaluation of tensile strength of surgical synthetic absorbable suture materials: an in vitro study  

PubMed Central

Purpose The purpose of this study was to evaluate the tensile strength of surgical synthetic absorbable sutures over a period of 14 days under simulated oral conditions. Methods Three suture materials (polyglycolic acid [PGA], polyglactin [PG] 910, and poly (glycolide-co-?-caprolactone) [PGC]) were used in 4-0 and 5-0 gauges. 210 suture samples (35 of each material and gauge) were used. All of the samples were tested preimmersion and 1 hour and 1, 3, 7, 10, and 14 days postimmersion. The tensile strength of each suture material and gauge was assessed. The point of breakage and the resorption pattern of the sutures were also assessed. Results During the first 24 hours of immersion, all 4-0 and 5-0 samples of PGA, PG 910, and PGC maintained their initial tensile strength. At baseline (preimmersion), there was a statistically significant (P<0.001) difference in the tensile strengths between the 4-0 and 5-0 gauge of PGA, PG 910, and PGC. PGA 4-0 showed the highest tensile strength until day 10. At 7 days, all the 4-0 sutures of the three materials had maintained their tensile strength with PGA 4-0 having significantly greater (P=0.003) tensile strength compared to PG. Conclusions 4-0 sutures are stronger and have greater tensile strength than 5-0 sutures. The PGA 4-0 suture showed the highest tensile strength at the end of day 10. PMID:23837127

Ranganath, V.; Nichani, Ashish Sham

2013-01-01

51

Tensile Properties of Hydrogels and of Snake Skin  

NASA Technical Reports Server (NTRS)

Stimulus-responsive or 'smart' gels are of potential interest as sensors and actuators, in industrial separations, and as permeable delivery systems. In most applications, a certain degree of mechanical strength and toughness will be required, yet the large-strain behavior of gels has not been widely reported. Some exceptions include work on gelatin and other food gels, some characterization of soft gels applicable for in-vitro cell growth studies, and toughness determinations on commercial contact lens materials. In general, it can be anticipated that the gel stiffness will increase with increasing degree of crosslinking, but the tensile strength may go through a maximum. Gel properties can be tailored by varying not only the degree of crosslinking, but also the polymer concentration and the nature of the polymer backbone (e.g. its stiffness or solubility). Polypeptides provide an especially interesting case, where secondary structure affects trends in moduli and conformational transitions may accompany phase changes. A few papers on the tensile properties of responsive gels have begun to appear. The responsive hydrogel chosen for the present study, crosslinked hydroxypropylcellulose, shrinks over a rather narrow temperature range near 44 C. Some vertebrate skin is also subject to substantial strain. Among reptiles, the morphologies of the skin and scales show wide variations. Bauer et al. described the mechanical properties and histology of gecko skin; longitudinal tensile properties of snake skin were examined by Jayne with reference to locomotion. The present measurements focus on adaptations related to feeding, including the response of the skin to circumferential tension. Tensile properties will be related to interspecific and regional variation in skin structure and folding.

Hinkley, Jeffrey A.; Savitzky, Alan H.; Rivera, Gabriel; Gehrke, Stevin H.

2002-01-01

52

Bulk metallic glass composite with good tensile ductility, high strength and large elastic strain limit.  

PubMed

Bulk metallic glasses exhibit high strength and large elastic strain limit but have no tensile ductility. However, bulk metallic glass composites reinforced by in-situ dendrites possess significantly improved toughness but at the expense of high strength and large elastic strain limit. Here, we report a bulk metallic glass composite with strong strain-hardening capability and large elastic strain limit. It was found that, by plastic predeformation, the bulk metallic glass composite can exhibit both a large elastic strain limit and high strength under tension. These unique elastic mechanical properties are attributed to the reversible B2?B19' phase transformation and the plastic-predeformation-induced complicated stress state in the metallic glass matrix and the second phase. These findings are significant for the design and application of bulk metallic glass composites with excellent mechanical properties. PMID:24931632

Wu, Fu-Fa; Chan, K C; Jiang, Song-Shan; Chen, Shun-Hua; Wang, Gang

2014-01-01

53

Tensile and creep properties of titanium-vanadium, titanium-molybdenum, and titanium-niobium alloys  

NASA Technical Reports Server (NTRS)

Tensile and creep properties of experimental beta-titanium alloys were determined. Titanium-vanadium alloys had substantially greater tensile and creep strength than the titanium-niobium and titanium-molybdenum alloys tested. Specific tensile strengths of several titanium-vanadium-aluminum-silicon alloys were equivalent or superior to those of commercial titanium alloys to temperatures of 650 C. The Ti-50V-3Al-1Si alloy had the best balance of tensile strength, creep strength, and metallurgical stability. Its 500 C creep strength was far superior to that of a widely used commercial titanium alloy, Ti-6Al-4V, and almost equivalent to that of newly developed commercial titanium alloys.

Gray, H. R.

1975-01-01

54

Flexural and tensile strength developments of various shape carbon fiber-reinforced lightweight cementitious composites  

SciTech Connect

Effects of three types of carbon fiber shapes (C, round, and hollow shape) on tensile and flexural strength developments of randomly oriented carbon-fiber-reinforced lightweight cement composites (CFRLC) were investigated. C-shape CFRLC (C-CFRLC) showed higher tensile and flexural strength development than any other shape. C-CFRLC loading V{sub f} = 3% in particular increased about 40% in tensile and flexural strength, compared to round shape CFRLC (R-CFRLC). Hollow-shape CFRLC (H-CFRLC) showed slightly higher tensile and flexural strength than R-CFRLC. C-CFRLC presented stronger fiber-matrix interfacial adhesive force, due to mechanical anchorage into the matrix, than any other fibers. Silica fume significantly influences the increase of tensile and flexural strength for the CFRLC.

Kim, T.J.; Park, C.K. [Ssangyong Research Center, Taejon (Korea, Republic of)] [Ssangyong Research Center, Taejon (Korea, Republic of)

1998-07-01

55

Tensile properties of Inconel 718 after low temperature neutron irradiation  

NASA Astrophysics Data System (ADS)

Tensile properties of Inconel 718 (IN718) have been investigated after neutron irradiation to 0.0006-1.2 dpa at 60-100 °C in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). The alloy was exposed in solution-annealed (SA) and precipitation-hardened (PH) conditions. Before irradiation, the yield strength of PH IN718 was about 1170 MPa, which was 3.7 times higher than that of SA IN718. In the SA condition, an almost threefold increase in yield strength was found at 1.2 dpa, but the alloy retained a positive strain-hardening capability and a uniform ductility of more than 20%. Comparisons showed that the strain-hardening behavior of the SA IN718 is similar to that of a SA 316LN austenitic stainless steel. In the PH condition, the IN718 displayed no radiation-induced hardening in yield strength and significant softening in ultimate tensile strength. The strain-hardening capability of the PH IN718 decreased with dose as the radiation-induced dissolution of precipitates occurred, which resulted in the onset of plastic instability at strains less than 1% after irradiation to 0.16 or 1.2 dpa. An analysis on plastic instability indicated that the loss of uniform ductility in PH IN718 was largely due to the reduction in strain-hardening rate, while in SA IN718 and SA 316LN stainless steel it resulted primarily from the increase of yield stress.

Byun, T. S.; Farrell, K.

2003-05-01

56

Tensile strength of carbyne chains in varied chemical environments and structural lengths  

NASA Astrophysics Data System (ADS)

Carbyne and carbyne-based low-dimensional structures are promising for several applications including ultra-compact circuits and purification devices. Designing any applied carbyne-based structure requires a fundamental understanding of the mechanical strength of carbyne chains with different lengths at different temperatures and operating chemical environment. Here we use molecular dynamics simulations to investigate the strength of carbyne chains with different lengths at different temperatures. A theoretical framework based on statistical mechanics and molecular dynamics results is presented, proving a fast and insightful method for predicting the rupture force and its physical mechanism. The effect of water molecules’ interaction is also studied on the mechanical properties and it is shown that both the tensile strength and rupture strain are improved by the water interaction. The results of this work can be used for designing and analyzing the robustness and reliability of various carbyne-based materials and applied devices for varies working conditions.

Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J.

2014-09-01

57

Tensile strength of carbyne chains in varied chemical environments and structural lengths.  

PubMed

Carbyne and carbyne-based low-dimensional structures are promising for several applications including ultra-compact circuits and purification devices. Designing any applied carbyne-based structure requires a fundamental understanding of the mechanical strength of carbyne chains with different lengths at different temperatures and operating chemical environment. Here we use molecular dynamics simulations to investigate the strength of carbyne chains with different lengths at different temperatures. A theoretical framework based on statistical mechanics and molecular dynamics results is presented, proving a fast and insightful method for predicting the rupture force and its physical mechanism. The effect of water molecules' interaction is also studied on the mechanical properties and it is shown that both the tensile strength and rupture strain are improved by the water interaction. The results of this work can be used for designing and analyzing the robustness and reliability of various carbyne-based materials and applied devices for varies working conditions. PMID:25148690

Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J

2014-09-19

58

Effects of neutron irradiation on tensile properties of oxide dispersion strengthened (ODS) steel claddings  

NASA Astrophysics Data System (ADS)

The effects of fast neutron irradiation on ring tensile properties of oxide dispersion strengthened (ODS) steel claddings for fast reactor were investigated. Specimens were irradiated in the experimental fast reactor Joyo using the material irradiation rig at temperatures between 693 and 1108 K to fast neutron doses ranging from 16 to 33 dpa. The post-irradiation ring tensile tests were carried out at irradiation temperatures. The experimental results showed that there was no significant change in tensile strengths after neutron irradiation below 923 K, but the tensile strengths at neutron irradiation above 1023 K up to 33 dpa were decreased by about 20%. On the other hand, uniform elongation after irradiation was more than 2% at all irradiation conditions. The ring tensile properties of these ODS claddings remained excellent within these irradiation conditions compared with conventional 11Cr ferritic/martensitic steel (PNC-FMS) claddings.

Yano, Y.; Ogawa, R.; Yamashita, S.; Ohtsuka, S.; Kaito, T.; Akasaka, N.; Inoue, M.; Yoshitake, T.; Tanaka, K.

2011-12-01

59

Tensile properties of NiAl bicrystals  

SciTech Connect

The intermetallic compound {beta}-NiAl continues to receive considerable attention in spite of its lack of room temperature toughness and high temperature strength. Although the dislocations are mobile at room temperature, the lack of a sufficient number of slip systems precludes significant elongation in single and polycrystalline NiAl except in single crystals under special conditions. In the case of polycrystals of stoichiometric NiAl, the room temperature fracture tends to be mostly intergranular; this has been related to the stresses that build up at the grain boundaries during plastic deformation due to the lack of active independent deformation mechanisms or the possibility that the grain boundaries are intrinsically weak. The present study was designed to establish the condition of grain boundary fracture by performing tensile tests at different temperatures and strain rates on bicrystals of NiAl containing natural boundaries produced by Bridgman growth. This approach was selected based on the previous work on NiAl bicrystals produced by diffusion bonding/brazing and Bridgman growth. In some cases, these boundaries were reportedly enriched in nickel although it is unclear, based on the limited atomistic modeling efforts to date, whether this is a result of sample processing or is a characteristic of this compound. Furthermore, the previous studies of slip behavior were performed in compression which is less suitable for examining the relative strength of the grain boundaries.

LeBleu, J.B. Jr.; Mei, P.R.; Levit, V.I.; Kaufman, M.J. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering] [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering

1998-01-06

60

Tensile and flexural strength of commercially pure titanium submitted to laser and tungsten inert gas welds.  

PubMed

This study evaluated the tensile and flexural strength of tungsten inert gas (TIG) welds in specimens made of commercially pure titanium (CP Ti) compared with laser welds. Sixty cylindrical specimens (2 mm diameter x 55 mm thick) were randomly assigned to 3 groups for each test (n=10): no welding (control), TIG welding (10 V, 36 A, 8 s) and Nd:YAG laser welding (380 V, 8 ms). The specimens were radiographed and subjected to tensile and flexural strength tests at a crosshead speed of 1.0 mm/min using a load cell of 500 kgf applied on the welded interface or at the middle point of the non-welded specimens. Tensile strength data were analyzed by ANOVA and Tukey's test, and flexural strength data by the Kruskal-Wallis test (?=0.05). Non-welded specimens presented significantly higher tensile strength (control=605.84 ± 19.83) (p=0.015) and flexural strength (control=1908.75) (p=0.000) than TIG- and laser-welded ones. There were no significant differences (p>0.05) between the welding types for neither the tensile strength test (TIG=514.90 ± 37.76; laser=515.85 ± 62.07) nor the flexural strength test (TIG=1559.66; laser=1621.64). As far as tensile and flexural strengths are concerned, TIG was similar to laser and could be suitable to replace laser welding in implant-supported rehabilitations. PMID:24474361

Atoui, Juliana Abdallah; Felipucci, Daniela Nair Borges; Pagnano, Valéria Oliveira; Orsi, Iara Augusta; Nóbilo, Mauro Antônio de Arruda; Bezzon, Osvaldo Luiz

2013-01-01

61

Increased Tensile Strength of Carbon Nanotube Yarns and Sheets through Chemical Modification and Electron Beam Irradiation  

NASA Technical Reports Server (NTRS)

The inherent strength of individual carbon nanotubes offers considerable opportunity for the development of advanced, lightweight composite structures. Recent work in the fabrication and application of carbon nanotube (CNT) forms such as yarns and sheets has addressed early nanocomposite limitations with respect to nanotube dispersion and loading; and has pushed the technology toward structural composite applications. However, the high tensile strength of an individual CNT has not directly translated to macro-scale CNT forms where bulk material strength is limited by inter-tube electrostatic attraction and slippage. The focus of this work was to assess post processing of CNT sheet and yarn to improve the macro-scale strength of these material forms. Both small molecule functionalization and e-beam irradiation was evaluated as a means to enhance tensile strength and Youngs modulus of the bulk CNT material. Mechanical testing results revealed a tensile strength increase in CNT sheets by 57 when functionalized, while an additional 48 increase in tensile strength was observed when functionalized sheets were irradiated; compared to unfunctionalized sheets. Similarly, small molecule functionalization increased yarn tensile strength up to 25, whereas irradiation of the functionalized yarns pushed the tensile strength to 88 beyond that of the baseline yarn.

Miller, Sandi G.; Williams, Tiffany S.; Baker, James S.; Sola, Francisco; Lebron-Colon, Marisabel; McCorkle, Linda S.; Wilmoth, Nathan G.; Gaier, James; Chen, Michelle; Meador, Michael A.

2014-01-01

62

The effect of tensile prestraining on 2024-T851 aluminum mechanical properties  

NASA Astrophysics Data System (ADS)

The effects of a tensile prestrain on the mechanical properties of 2024-T851 aluminum were investigated. Specifically, the effect of a 3% tensile prestrain on the offset yield strength, ultimate strength, compressive yield strength, resilience, and toughness was studied. Smooth tensile bars and notched round bars were used to study the interaction between internally generated hydrostatic stress and the tensile prestrain. Prestrain effects on material damage were also studied, using both tensile bars and notched round bars to evaluate the combined effect of internal hydrostatic stress and prestrain on damage. As expected, a tensile prestrain had favorable effects on 2024-T851, such as increased yield strength and resilience. However, compressive yield strength and the modulus of toughness decreased significantly (41% and 45% respectively). The damage variable decreased as much as 38% for smooth tensile bars. However, the damage values of prestrained notched round bars were greater than baseline notched round bars until fracture. These results suggest that prestraining 2024-T851 should be carefully examined due to the potentially harmful effects.

Poore, Adam Lawrence

63

The Cryogenic Tensile Properties of an Extruded Aluminum-Beryllium Alloy  

NASA Technical Reports Server (NTRS)

Basic mechanical properties; i.e., ultimate tensile strength, yield strength, percent elongation, and elastic modulus, were obtained for the aluminum-beryllium alloy, AlBeMet162, at cryogenic (-195.5 C (-320 F) and -252.8 C (-423 F)) temperatures. The material evaluated was purchased to the requirements of SAE-AMS7912, "Aluminum-Beryllium Alloy, Extrusions."

Gamwell, W. R.

2002-01-01

64

Relationships between tensile strength, morphology and crystallinity of treated kenaf bast fibers  

NASA Astrophysics Data System (ADS)

Surface treatments on kenaf bast fibers were carried out with steam, alkali and a combination of steam-alkali. To verify and gain an understanding of their inter-relationship, tensile strength, surface morphology and crystallinity of treated and raw fibers were characterized. Tensile strength of fibers was measured with a universal tensile machine (UTM), crystallinity was estimated using X-ray diffraction (XRD) and Fourier transformation infrared (FTIR) spectroscopy, and surface morphology was examined by scanning electron microscopy (SEM). Tensile strength of the treated fibers was higher than that of the raw fiber. Tensile strength increased after steam treatment and was further improved by alkali treatment, but slightly reduced after steam treatment followed by alkalization. Increase of concentration of alkali tended to increase tensile strength. Differences in tensile strength of the treated fibers are discussed in relation to the changes in surface morphology and crystallinity. Understanding of these relationships may provide direction towards the goal of producing better performance of natural fiber composites.

Sosiati, H.; Rohim, Ar; Ma`arif, Triyana, K.; Harsojo

2013-09-01

65

Effect of the strain-induced melt activation (SIMA) process on the tensile properties of a new developed super high strength aluminum alloy modified by Al-5Ti-1B grain refiner  

SciTech Connect

In this study, the effect of Al-5Ti-1B grain refiners and modified strain-induced melt activation process on an Al-Zn-Mg-Cu alloy was studied. The optimum level of Ti was found to be 0.1 wt.%. The specimens subjected to deformation ratio of 40% (at 300 Degree-Sign C) and various heat treatment times (10-40 min) and temperature (550-600 Degree-Sign C) regimes were characterized in this study. Reheating condition to obtain a fine globular microstructure was optimized. Microstructural examinations were conducted by optical and scanning electron microscopy coupled with an energy dispersive spectrometry. The optimum temperature and time in strain-induced melt activation process are 575 Degree-Sign C and 20 min, respectively. T6 heat treatment including quenching to room temperature and aging at 120 Degree-Sign C for 24 h was employed to reach to the maximum strength. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment. After the T6 heat treatment, the average tensile strength increased from 283 MPa to 587 and 332 MPa to 617 for samples refined with 2 wt.% Al-5Ti-1B before and after strain-induced melt activation process and extrusion process, respectively. Ultimate strength of Ti-refined specimens without SIMA process has a lower value than globular microstructure specimens after SIMA and extrusion process. - Highlights: Black-Right-Pointing-Pointer The effect of Al-5Ti-1B on the aluminum alloy produced by SIMA process was studied. Black-Right-Pointing-Pointer Al-5Ti-1B is an effective in reducing the grain and reagent fine microstructure. Black-Right-Pointing-Pointer Reheating condition to obtain a fine globular microstructure was optimized. Black-Right-Pointing-Pointer The optimum temperature and time in SIMA process are 575 Degree-Sign C and 20 min respectively. Black-Right-Pointing-Pointer UTS of globular structure specimens have a more value than Ti-refined specimens.

Haghparast, Amin [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)] [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nourimotlagh, Masoud [Young Researchers Club, Dareshahr Branch, Islamic Azad university (Iran, Islamic Republic of)] [Young Researchers Club, Dareshahr Branch, Islamic Azad university (Iran, Islamic Republic of); Alipour, Mohammad, E-mail: Alipourmo@ut.ac.ir [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)] [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

2012-09-15

66

Predicting the Open-Hole Tensile Strength of Composite Plates Based on Probabilistic Neural Network  

NASA Astrophysics Data System (ADS)

Tensile experiments were performed for open-hole composite plates with three different layups. With the limited number of experimental results, a probabilistic neural network (PNN) based approach is proposed to predict the tensile strength of composite plates with an open-hole. The predictive model takes the geometric parameters, the layup features and the average tensile stress of open-hole composite plates as the inputs and produces the safety status as the intermediate output with the classification function of PNN. Then the critical safety point, that is the open-hole tensile strength, where the safety status turns from survival to failure, is determined with the bi-section searching method. The predictions produce acceptable results whose errors are comparable to the coefficient of variation of experimental results. With experimental data from other studies, further assessments are also made to prove the capability of this model in predicting the open-hole tensile strength of composite plates.

Fan, Hai-Tao; Wang, Hai

2014-12-01

67

Characterization of the Compressive and Fracture Behavior, as Well as the Residual Tensile Strength of a Polyurethane Foam.  

E-print Network

??Experiments were conducted on polyurethane foam to determine its compressive strength/modulus, relaxation behavior, fracture toughness, as well as residual tensile strength after repetitive compression at… (more)

Zhang, Yanli

2007-01-01

68

Experimental and Numerical Study on Tensile Strength of Concrete under Different Strain Rates  

PubMed Central

The dynamic characterization of concrete is fundamental to understand the material behavior in case of heavy earthquakes and dynamic events. The implementation of material constitutive law is of capital importance for the numerical simulation of the dynamic processes as those caused by earthquakes. Splitting tensile concrete specimens were tested at strain rates of 10?7?s?1 to 10?4?s?1 in an MTS material test machine. Results of tensile strength versus strain rate are presented and compared with compressive strength and existing models at similar strain rates. Dynamic increase factor versus strain rate curves for tensile strength were also evaluated and discussed. The same tensile data are compared with strength data using a thermodynamic model. Results of the tests show a significant strain rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain rate. In the quasistatic strain rate regime, the existing models often underestimate the experimental results. The thermodynamic theory for the splitting tensile strength of concrete satisfactorily describes the experimental findings of strength as effect of strain rates. PMID:24883355

Min, Fanlu; Yao, Zhanhu; Jiang, Teng

2014-01-01

69

Experimental and numerical study on tensile strength of concrete under different strain rates.  

PubMed

The dynamic characterization of concrete is fundamental to understand the material behavior in case of heavy earthquakes and dynamic events. The implementation of material constitutive law is of capital importance for the numerical simulation of the dynamic processes as those caused by earthquakes. Splitting tensile concrete specimens were tested at strain rates of 10(-7) s(-1) to 10(-4) s(-1) in an MTS material test machine. Results of tensile strength versus strain rate are presented and compared with compressive strength and existing models at similar strain rates. Dynamic increase factor versus strain rate curves for tensile strength were also evaluated and discussed. The same tensile data are compared with strength data using a thermodynamic model. Results of the tests show a significant strain rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain rate. In the quasistatic strain rate regime, the existing models often underestimate the experimental results. The thermodynamic theory for the splitting tensile strength of concrete satisfactorily describes the experimental findings of strength as effect of strain rates. PMID:24883355

Min, Fanlu; Yao, Zhanhu; Jiang, Teng

2014-01-01

70

Strength Prediction of Composite ? Joints Under Tensile Load  

Microsoft Academic Search

Application of an all-composite ? joint as a structural connector for integrated aircraft structures can potentially enable both weight and assembly cost benefits while retaining good load carrying capability. This article is concerned with the behavior of an all-composite ? joint under a static, tensile load. The damage onset, propagation, and ultimate collapse of the composite ? joint are simulated

Libin Zhao; Tianliang Qin; R. Ajit Shenoi; Jianyu Zhang; Xianzhu Liang; Hai Huang

2010-01-01

71

SIZE EFFECT ON CONCRETE SPLITTING TENSILE STRENGTH AND MODULUS OF ELASTICITY  

Microsoft Academic Search

The work presented in this paper is part of an experimental investigation program regarding the tensile behavior of intermediate\\u000a strength concrete. In total, ninety-one oncrete cylinder specimens were casted and eighty-two of them were tested in uniaxial\\u000a compression and indirect tension. The concrete specimens were systematically varied in size. The splitting tensile strength\\u000a and modulus of elasticity of concrete exhibited

A. Kanos; P. C. Perdikaris

72

The tensile strength of the cometary surface: Laboratory experiments and implications on formation scenarios  

NASA Astrophysics Data System (ADS)

One big question in cometary physics is how the gas pressure can overcome the tensile strength of the surface material to effectively release dust from the cometary surface. Thus, we have performed laboratory experiments in order to measure the tensile strength of the cometary surface by using silica aggregates as an analog sample material. During this conference we would like to present our experimental results and to discuss how different formation scenarios can have influenced the activity of comets.

Gundlach, B.; Blum, J.

2014-07-01

73

Factors limiting the tensile strength of PBO-based carbon fibers  

Microsoft Academic Search

Poly p-phenylene benzobisoxazole (PBO) converts directly to carbon fiber without stabilization. However, the applicability of PBO-based carbon fibers is limited by their low tensile strength. This paper represents the first study of the high-temperature conversion of PBO to carbon fiber and examines some factors leading to this low tensile strength. A mixed-mode Weibull analysis implies that the flaws present in

J. A. Newell; D. D. Edie

1996-01-01

74

Dynamic tensile strength of terrestrial rocks and application to impact cratering  

Microsoft Academic Search

Dynamic tensile strengths and fracture strengths of 3 terrestrial rocks, San Marcos gabbro, Coconino sandstone, and Sesia eclogite were determined by carrying out flat-plate (PMMA and aluminum) impact experiments on disc-shaped samples in the 5 to 60 m\\/sec range. Tensile stresses of 125 to 300 MPa and 245 to 580 MPa were induced for gabbro and eclogite, respectively (with duration

Huirong-Anita Ai; Thomas J. Ahrens

2004-01-01

75

Tensile Properties of Commonly Used Prolapse Meshes  

PubMed Central

Objectives Although most currently available synthetic meshes are lightweight, macroporous polypropylene, they differ in regard to pore size, knit pattern and surface characteristics, all of which may impact behavior. In this study, we compare the biomechanical properties of 4 commonly used prolapse meshes relative to Gynecare PS ™, using a tensile testing protocol. Methods Full length meshes [Gynecare PS™ (Ethicon), Pelvitex ™ (Bard), Popmesh™, Timesh ™ (Caldera), and Polyform (Boston Scientific)] were divided into 15 × 5 cm samples. Light microscopy was used to define pore size. For tensile testing, each mesh was either loaded to failure (n=5 per group) or cyclically loaded (n=3 per group). Data abstracted from the largely bilinear load-elongation curves included the low and high stiffness, the point of transition between them (inflection point), the load at failure, and the relative elongation. Results Microscopic analysis demonstrated that the pore size for all of the meshes were distinct. With the exception of Popmesh which displayed linear behavior, all prolapse meshes were characterized by a very low initial stiffness increasing by an order of magnitude into the high stiffness region. The newer meshes were 70%-90% less stiff than Gynecare (p< 0.05) and more readily deformed in response to cyclical loading (greater permanent elongation; p < 0.001). There was a significant positive correlation between mesh weight and load at failure, (p< 0.001). Conclusions Newer meshes are significantly less stiff than Gynecare PS. The significant amount of permanent elongation of these meshes may be important to consider, especially during the early post-operative period when tissue in growth has yet to take place. PMID:19495548

Jones, Keisha A.; Feola, Andrew; Meyn, Leslie; Abramowitch, Steven D.; Moalli, Pamela A.

2010-01-01

76

Enzymatic Surface Erosion of High Tensile Strength Polycarbonates Based on Natural Phenols  

PubMed Central

Surface erosion has been recognized as a valuable design tool for resorbable biomaterials within the context of drug delivery devices, surface coatings, and when precise control of strength retention is critical. Here we report on high tensile strength, aromatic–aliphatic polycarbonates based on natural phenols, tyrosol (Ty) and homovanillyl alcohol (Hva), that exhibit enzymatic surface erosion by lipase. The Young’s moduli of the polymers for dry and fully hydrated samples are 1.0 to 1.2 GPa and 0.8 to 1.2 GPa, respectively. Typical characteristics of enzymatic surface erosion were confirmed for poly(tyrosol carbonate) films with concomitant mass-loss and thickness-loss at linear rates of 0.14 ± 0.01 mg cm–2 d–1 and 3.0 ± 0.8 ?m d–1, respectively. The molecular weight and the mechanical properties of the residual films remained constant. Changing the ratio of Ty and Hva provided control over the glass transition temperature (Tg) and the enzymatic surface erosion: increasing the Hva content in the polymers resulted in higher Tg and lower enzymatic erosion rate. Polymers with more than 50 mol % Hva were stable at 37 °C in enzyme solution. Analysis on thin films using quartz crystal microbalance with dissipation (QCM-D) demonstrated that the onset temperature of the enzymatic erosion was approximately 20 °C lower than the wet Tg for all tested polymers. This new finding demonstrates that relatively high tensile strength polycarbonates can undergo enzymatic surface erosion. Moreover, it also sheds light on the connection between Tg and enzymatic degradation and explains why few of the high strength polymers follow an enzyme-meditated degradation pathway. PMID:24432806

2015-01-01

77

Tensile and fatigue properties of 17-4 PH stainless steel at high temperatures  

Microsoft Academic Search

The tensile and high-cycle fatigue properties for 17-4 PH* stainless steels in three different conditions were investigated\\u000a at temperatures ranging from room temperature to 400 C. Results indicated that the yield strength and fatigue strength for\\u000a the three conditions at a given temperature took the following order: condition H900 > condition A> condition H1150. The yield\\u000a strength of each condition

Jui-Hung Wu; Chih-Kuang Lin

2002-01-01

78

Impact of a microwave curing process on tensile strength of selected carbon fiber composites  

NASA Astrophysics Data System (ADS)

The traditional process for curing carbon fiber (CF) composites has been the autoclave system. A review of recent research indicates curing CF composites in a microwave oven has the potential for reducing processing time. The problem statement of the experimental study was that the impact of a microwave curing process on tensile strength of selected CF composite specimens was unknown. The research study describes the statistical procedure and analysis of data to answer the specific question for the experimental trials: What is the effect on the tensile strength of cured CF composite samples due to the relationship of the autoclave and microwave curing process cycle time and temperature? ASTM International standard test method designation D 5083 - 02 was used for testing tensile strength of reinforced carbon fiber plastics using straight-sided specimens. Analytical data was obtained for evaluating the effects of process cycle time and temperature on tensile strength of the CF composite specimens. The result was that curing time of the autoclave system and microwave process had significant effects on the maximum tensile stress of CF composite specimen. Although 83% faster than the autoclave system, the microwave curing process had CF specimens with lower maximum tensile strength compared with the autoclave system results. The primary reason for the difference was that the microwave process did not use vacuum or pressure. Considering the cost/benefit ratio, the research study indicated that the microwave oven would be a viable and efficient process for curing CF composites.

Balzer, Brian B.

79

The effects of sterilization on the tensile strength of orthodontic wires.  

PubMed

The purpose of this study was to evaluate the effect of sterilization on the tensile strength of 0.016" beta-titanium, nickel titanium and stainless steel wires. Three common methods of sterilization--autoclaving, dry heat and ethylene oxide--were evaluated in three test trials involving zero, one and five sterilization cycles. For each of the test trials, five pieces each of 0.016" TMA, 0.016" Sentalloy and 0.016" Tru-chrome stainless steel wires were sterilized using a standard autoclave. Five other pieces of each of the same wires were sterilized in a dryclave, while an additional five pieces of each of the three wire types were sterilized using ethylene oxide. The ultimate tensile strengths of the wires were then determined using an Instron Universal Testing Machine. The data were compared for statistical differences using analysis of variance. The results showed that dry heat sterilization significantly increased the tensile strength of TMA wires after one cycle, but not after five cycles. Autoclaving and ethylene oxide sterilization did not significantly alter the tensile strength of TMA wires. Dry heat and autoclave sterilization also significantly increased the tensile strength of Sentalloy wires, but the mean strength after five sterilization cycles was not significantly different than after one cycle. Ethylene oxide sterilization of Sentalloy wires did not significantly alter the tensile strengths of that wire. There were no significant differences in the tensile strengths of the stainless steel wires following zero, one or five cycles for any of the sterilization methods. PMID:8498702

Staggers, J A; Margeson, D

1993-01-01

80

Establishing Correlations for Predicting Tensile Properties Based on the Shear Punch Test and Vickers Microhardness data  

NASA Astrophysics Data System (ADS)

A series of mechanical tests was performed on a matrix of pressure vessel alloys to establish correlations between shear punch tests (SPT), microhardness (Hv), and tensile data. The purpose is to estimate tensile properties from SPT and Hv data. Small specimen testing is central to characterization of irradiation-induced changes in alloys used for nuclear applications. SPT have the potential for estimating tensile yield and ultimate strengths, strain hardening and ductility data, by using TEM disks, for example. Additional insight into SPT was gained by performing finite element analysis (FEA) simulations.

Milot, Timothy S.

81

Effect of abrasive wear on the tensile strength of steel wire rope  

Microsoft Academic Search

Known amounts of external abrasive wear were introduced into a new 6-strand steel wire rope and the effects of this wear on the tensile strength of the rope examined against the rope discard criteria for wear stated in ISO 4309: 1990 and other selected international standards. The variations of strength with degree of wear in the test rope were compared

A. R. T. de Silva; Long Woon Fong

2002-01-01

82

THE INFLUENCE OF FORMATION ON TENSILE STRENGTH OF PAPER MADE FROM MECHANICAL PULPS  

Microsoft Academic Search

The importance of paper formation is widely appreciated amongst papermakers in relation to sheet appearance, but much remains unclear about its role in paper strength, particularly for paper made from mechanical pulps. This paper addressed the question of how formation affects the tensile strength of such pulps. Two softwoods mechanical pulps from species of differing fibre length and coarseness were

Mousa M. Nazhad; Emma J. Harris; Christopher T. J. Dodson; Richard J. Kerekes

83

Ideal tensile and shear strength of a gum metal approximant: Ab initio density functional calculations  

NASA Astrophysics Data System (ADS)

The ideal tensile and shear strengths of binary ?-phase Ti3Nb alloys have been investigated using ab initio density functional calculations. The binary alloy is considered as an approximant to the multifunctional Ti-Nb-Ta-Zr-O alloy known as “gum metal,” which displays high strength, low elastic modulus, high yield strain, and very good ductility. This alloy has been reported to deform elastically until the stress approaches the ideal tensile strength. Our calculations have been performed for an optimized chemical decoration of the body-centered cubic (bcc) structure of the ? phase. Previous work has demonstrated that this model yields elastic constants in very good agreement with those measured for gum metal specimens and leads to a reasonably accurate description of the martensitic transformations between the bcc ?, the orthorhombic ?'' and the hexagonal ? phases [Lazar , Phys. Rev. BPLRBAQ0556-280510.1103/PhysRevB.84.054202 84, 054202 (2011)]. The simulations of the response to tensile and shear loading have been performed for large supercells which account also for the different orientations of the -Nb-Nb- chains characteristic for the ?-phase structure relative to the direction of the applied load. The energy-strain and stress-strain curves are found to be very different from those reported for all bcc metals. Under uniaxial <100> loading we find an ideal tensile strength of 2.4 GPa, the upper limit to the tensile stress arising from a shear instability of the structure. Under uniaxial <110> load we calculate an ideal tensile strength of 2.2 or 2.8 GPa, depending on the orientation of the -Nb-Nb- chains relative to the loading direction. For a realistic multidomain structure the ideal strength is expected to correspond to the average of these values. An ideal strength of 2.6 GPa under <110> loading is roughly the same as under <100> load, despite a considerable anisotropy of the tensile moduli. For {211}<111> shear we calculate an ideal shear strength of 1.6 GPa, again as an average over different possible shearing directions relative to the Nb-Nb bonds. For the {110}<110> shear system we find a lower strength of 0.9 GPa. The structures reached at the stress maximum under <100> uniaxial tension and {211}<111> shear are identical, and since the maximal shear stress is much lower than the tensile stress, the alloy will fail by shear even under strictly uniaxial tension. The values of the ideal tensile and shear strengths are significantly low, even in comparison with those calculated for bcc V and Nb with very small shear moduli and approach the values reported for gum metal alloys.

Nagasako, Naoyuki; Asahi, Ryoji; Hafner, Jürgen

2012-01-01

84

Characterization of Optical Fiber Strength Under Applied Tensile Stress and Bending Stress  

SciTech Connect

Various types of tensile testing and bend radius tests were conducted on silica core/silica cladding optical fiber of different diameters with different protective buffer coatings, fabricated by different fiber manufacturers. The tensile tests were conducted to determine not only the average fiber strengths at failure, but also the distribution in fracture strengths, as well as the influence of buffer coating on fracture strength. The times-to-failure of fiber subjected to constant applied bending stresses of various magnitudes were measured to provide a database from which failure times of 20 years or more, and the corresponding minimum bend radius, could be extrapolated in a statistically meaningful way. The overall study was done to provide an understanding of optical fiber strength in tensile loading and in applied bending stress as related to applications of optical fiber in various potential coizfgurations for weapons and enhanced surveillance campaigns.

P.E. Klingsporn

2011-08-01

85

Contribution of hydroxyapatite to the tensile strength of the isobutyl-2-cyanoacrylate-bone bond.  

PubMed

The bonding strength between bone and alpha-2-cyanoacrylate polymers, with or without the addition of powdered hydroxyapatite, was determined. The tensile strength of a bone-cyanoacrylate bond was measured for each polymer: 4.31 +/- 0.88 MPa (methyl-), 5.74 +/- 0.62 MPa (ethyl-), and 8.33 +/- 0.41 MPa (isobutyl-). The tensile strength of the isobutyl-2-cyanoacrylate bond increased to 12.03 +/- 0.72 MPa with the addition of 10% (w/v) hydroxyapatite before decreasing to 7.89 +/- 0.58 MPa on addition of 15% (w/v) hydroxyapatite. An optimal concentration of hydroxyapatite significantly increased the tensile strength of a bone-cyanocacrylate bond in vitro in a manner comparable to reinforced bone replacement materials. PMID:2720039

Papatheofanis, F J

1989-04-01

86

Strength properties of separators in alkaline solutions  

SciTech Connect

Battery separator non-wovens that were coated with regenerated cellulose via the viscose process were subjected to storage in 40% potassium hydroxide (KOH) over a two month period. Samples were periodically checked for wet MD tensile strength. The test showed that among the non-wovens, the polyamide retained about 93% of its initial tensile strength whereas polyvinyl alcohol and cellulosic non-wovens retained only 55% and 35%, respectively. Adding a viscose coating to the non-wovens improved tensile strength retention by 20--25% for the polyvinyl alcohol and cellulosic materials. The viscose-coated polyamide retained more than 98% of its initial tensile strength.

Danko, T. [Viskase Corp., Chicago, IL (United States)

1996-11-01

87

Addition of antibacterial agents to MMA-TBB dentin bonding systems--influence on tensile bond strength and antibacterial effect.  

PubMed

To produce a bonding system which has both high bond strength and antibacterial properties, an antibacterial agent (vancomycin: VCM or metronidazol: MN) was added to the PMMA powder of 4-META/MMA-TBB resin (CB). The influence of the addition of an antibacterial agent on tensile bond strength to dentin and the antibacterial effect were investigated in this study. Forty-seven freshly extracted bovine first or second incisors were used to measure the tensile bond strength to dentin. The bond strengths to bovine dentin were not significantly decreased by addition of VCM (1%, 2%, 5%), or MN (1%) to CB (p < 0.05). The antibacterial effect of CB containing antibacterial agent on six strains of bacteria was investigated by the agar plate diffusion method, analyzing the appearance of the inhibition zone around a resin disk following anaerobic culturing. The resin disks containing VCM showed antibacterial effects on all of the strains examined; the widths of the inhibition zones were 4-15 mm. The resin disks containing MN showed antibacterial effects on three strains; the widths of the inhibition zones were 0-4 mm. It was thus possible to produce a bonding system with both antibacterial effect and high tensile bond strength by addition of VCM to PMMA powder. PMID:11219091

Kudou, Y; Obara, K; Kawashima, T; Kubota, M; Abe, S; Endo, T; Komatsu, M; Okuda, R

2000-03-01

88

Tensile bond strength of metal bracket bonding to glazed ceramic surfaces with different surface conditionings  

PubMed Central

Objective The objective of this study was to compare the tensile bond strength of metal brackets bonding to glazed ceramic surfaces using three various surface treatments. Materials and Methods Forty two glazed ceramic disks were assigned to three groups. In the first and second groups the specimens were etched with 9.5% hydrofluoric acid (HFA). Subsequently in first group, ceramic primer and adhesive were applied, but in second group a bonding agent alone was used. In third group, specimens were treated with 35% phosphoric acid followed by ceramic primer and adhesive application. Brackets were bonded with light cure composites. The specimens were stored in distilled water in the room temperature for 24 hours and thermocycled 500 times between 5°C and 55°C. The universal testing machine was used to test the tensile bond strength and the adhesive remenant index scores between three groups was evaluated. The data were subjected to one-way ANOVA, Tukey and Kruskal-Wallis tests respectively. Results The tensile bond strength was 3.69±0.52 MPa forfirst group, 2.69±0.91 MPa for second group and 3.60±0.41 MPa for third group. Group II specimens showed tensile strength values significantly different from other groups (P<0.01). Conclusion In spite of limitations in laboratory studies it may be concluded that in application of Scotch bond multipurpose plus adhesive, phosphoric acid can be used instead of HFA for bonding brackets to the glazed ceramic restorations with enough tensile bond strength. PMID:22509459

Akhoundi, MS. Ahmad; Kamel, M. Rahmati; Hashemi, SH. Mahmood; Imani, M.

2011-01-01

89

Environmental effects on the tensile strength of chemically vapor deposited silicon carbide fibers  

NASA Technical Reports Server (NTRS)

The room temperature and elevated temperature tensile strengths of commercially available chemically vapor-deposited (CVD) silicon carbide fibers were measured after 15 min heat treatment to 1600 C in various environments. These environments included oxygen, air, argon and nitrogen at one atmosphere and vacuum at 10/9 atmosphere. Two types of fibers were examined which differed in the SiC content of their carbon-rich coatings. Threshold temperature for fiber strength degradation was observed to be dependent on the as-received fiber-flaw structure, on the environment and on the coating. Fractographic analyses and flexural strength measurements indicate that tensile strength losses were caused by surface degradation. Oxidation of the surface coating is suggested as one possible degradation mechanism. The SiC fibers containing the higher percentage of SiC near the surface of the carbon-rich coating show better strength retention and higher elevated temperature strength.

Bhatt, R. T.; Kraitchman, M. D.

1985-01-01

90

A modified Johnson–Cook model for tensile behaviors of typical high-strength alloy steel  

Microsoft Academic Search

The uniaxial tensile tests were conducted with the initial strain rates range of (0.0001–0.01)s?1 and the temperature range of (1123–1373)K for typical high-strength alloy steel. Based on the experimental results, the modified Johnson–Cook model, which considers the coupled effects of strain, strain rate and deformation temperature, was proposed to describe the tensile behaviors of the studied alloy steel. Results show

Y. C. Lin; Xiao-Min Chen; Ge Liu

2010-01-01

91

Change in Tensile Properties of Neoprene and Nitrile Gloves After Repeated Exposures to Acetone and Thermal Decontamination  

Microsoft Academic Search

This study investigated the change in tensile properties of neoprene and nitrile gloves after repeated cycles of exposure to acetone, followed by thermal decontamination. The glove was exposed to acetone (outer surface in contact with chemical), subjected to thermal decontamination, and tested for the tensile strength and the ultimate elongation. Thermal decontamination was carried out inside an oven for 16

Pengfei Gao; Beth Tomasovic

2005-01-01

92

Elevated-temperature tensile and creep properties of several ferritic stainless steels  

NASA Technical Reports Server (NTRS)

The elevated-temperature mechanical properties of several ferritic stainless steels were determined. The alloys evaluated included Armco 18SR, GE 1541, and NASA-18T-A. Tensile and creep strength properties at 1073 and 1273 K and residual room temperature tensile properties after creep testing were measured. In addition, 1273 K tensile and creep tests and residual property testing were conducted with Armco 18SR and GE 1541 which were exposed for 200 hours to a severe oxidizing environment in automotive thermal reactors. Aside from the residual tensile properties for Armco 18SR, prior exposure did not affect the mechanical properties of either alloy. The 1273 K creep strength parallel to the sheet-rolling direction was similar for all three alloys. At 1073 K, NASA-18T-A had better creep strength than either Armco 18SR or GE 1541. NASA-18T-A possesses better residual properties after creep testing than either Armco 18SR or Ge 1541.

Whittenberger, J. D.

1977-01-01

93

Effects of strain rate on tensile properties of TZM and Mo-5%Re  

NASA Astrophysics Data System (ADS)

In the present work, we have studied the strain rate sensitivity of tensile properties of TZM and Mo-5%Re alloys. Tests were performed at room temperature and around the transition temperature of each alloy, at strain rates varying over five decades. Ductility appeared insensitive to strain rate, whereas the strength is found to be strain rate dependent. Both proof stress and ultimate tensile strength are affected by strain rate and the Mo-5%Re alloy is more sensitive than TZM. As expected, the hardening decreases with temperature; in TZM alloy the strain rate sensitivity was apparent only at room temperature.

Filacchioni, G.; Casagrande, E.; De Angelis, U.; De Santis, G.; Ferrara, D.

2002-12-01

94

Establishing a Mathematical Model to Predict the Tensile Strength of Friction Stir Welded Pure Copper Joints  

NASA Astrophysics Data System (ADS)

This investigation was undertaken to predict the tensile strength of friction stir welded pure copper. Response surface methodology based on a central composite rotatable design with four welding parameters, five levels, and 31 runs was used to conduct the experiments and to develop the mathematical regression model by means of Design-Expert software. Four welding parameters considered were tool profile design, rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted model. Confirmation experiments including microstructural characterization and conducted tensile tests showed that developed models are reasonably accurate. The results showed that the joints welded using the square and triangular tools had higher tensile strength compared to the joints welded using other tools. The increase in tool rotational speed, welding speed, and axial force resulted in increasing the tensile strength of the joints up to a maximum value. Also, the developed model showed that the optimum parameters to get a maximum of tensile strength were rotational speed, welding speed, and axial force of 942 rpm, 84 mm/min, and 1.62 kN, respectively.

Heidarzadeh, A.; Saeid, T.; Khodaverdizadeh, H.; Mahmoudi, A.; Nazari, E.

2013-02-01

95

Development of a silicon carbide fibre with high tensile strength  

Microsoft Academic Search

MUCH work has been done on preparing heat-resistant silicon carbide materials in fibrous form, since plastics or metals can be reinforced with them to obtain very heat-resistant material of great mechanical strength. SiC whiskers1 are, however, impractical because of their shortness (several mm), their non-uniform diameter and high cost of production. SiC-on-W (ref. 2) and SiC-on-C (ref. 3) filaments have

S. Yajima; J. Hayashi; M. Omori; K. Okamura

1976-01-01

96

A Novel Ni-Containing Powder Metallurgy Steel with Ultrahigh Impact, Fatigue, and Tensile Properties  

NASA Astrophysics Data System (ADS)

The impact toughness of powder metallurgy (PM) steel is typically inferior, and it is further impaired when the microstructure is strengthened. To formulate a versatile PM steel with superior impact, fatigue, and tensile properties, the influences of various microstructures, including ferrite, pearlite, bainite, and Ni-rich areas, were identified. The correlations between impact toughness with other mechanical properties were also studied. The results demonstrated that ferrite provides more resistance to impact loading than Ni-rich martensite, followed by bainite and pearlite. However, Ni-rich martensite presents the highest transverse rupture strength (TRS), fatigue strength, tensile strength, and hardness, followed by bainite, pearlite, and ferrite. With 74 pct Ni-rich martensite and 14 pct bainite, Fe-3Cr-0.5Mo-4Ni-0.5C steel achieves the optimal combination of impact energy (39 J), TRS (2170 MPa), bending fatigue strength at 2 × 106 cycles (770 MPa), tensile strength (1323 MPa), and apparent hardness (38 HRC). The impact energy of Fe-3Cr-0.5Mo-4Ni-0.5C steel is twice as high as those of the ordinary high-strength PM steels. These findings demonstrate that a high-strength PM steel with high-toughness can be produced by optimized alloy design and microstructure.

Wu, Ming-Wei; Shu, Guo-Jiun; Chang, Shih-Ying; Lin, Bing-Hao

2014-08-01

97

The effect of boron addition on the tensile properties of control-rolled and normalized C-Mn steels  

Microsoft Academic Search

Control-rolled and normalized C-Mn steels with and without boron alloying at two finish rolling temperatures of 800 °C and 1000°C were studied with respect to their tensile properties in order to investigate the role of boron in enhancing the strength of these materials. It was found that in boron steels ultimate tensile strength increased and impact transition temperature decreased owing

M. I. Haq; Nazma Ikram

1993-01-01

98

Tensile strength of five types of retention for resin-bonded prostheses.  

PubMed

The tensile bond strengths of five retention techniques for bonded cast restorations were tested. The retentive methods were the electrolytic etch, Rochette's perforations, retention beads, the recessed surface, and soldered orthodontic mesh. The electrolytic etch and recessed surface methods gave the highest values of bond strength, followed by retention beads. Rochette's perforations and the soldered orthodontic mesh failed to surpass the bond strength of the control group (no additional retention) after 1 hour and provided the lowest bond strength after 24 hours. PMID:1687153

Bastos, M T; Mondelli, J; Ishikiriama, A; Navarro, M F

1991-12-01

99

Tensile and thickness swelling properties of strands from  

E-print Network

-poplar (Liriodendron tulipifera L), red oak (Quercus spp.) and southern yellow pine (Pinus taeda L.)--were tested of engineering constants of strand composites. Among the four species tested, yellow-poplar strands demonstrated engineering con stants of strand composites. Tensile modulus and strength of sweet-gum strands, for example

100

Tensile Properties and Fracture Behavior of Different Carbon Nanotube-Grafted Polyacrylonitrile-Based Carbon Fibers  

NASA Astrophysics Data System (ADS)

The tensile properties and fracture behavior of different carbon nanotube (CNT)-grafted polyacrylonitrile-based (T1000GB) single carbon fibers were investigated. Grafting of CNTs was achieved via chemical vapor deposition (CVD). When Fe(C5H5)2 (also applied via CVD) was used as the catalyst, the tensile strength and Weibull modulus of the carbon fibers were improved, possibly due to the growth of dense CNT networks on the carbon fibers, which may have led to a reduction in the number of strength-limiting defects. Separately, at lower concentrations of an Fe(NO3)3·9H2O catalyst in ethanol, which was applied via dipping, the tensile strength of CNT-grafted fibers was nearly identical to that of the as-received fibers, although the Weibull modulus was higher. For higher concentrations of the Fe(NO3)3·9H2O catalyst, however, the tensile strength and the Weibull modulus were lower than those for the as-received material. Although the density of the CNT network increased with the concentration of the Fe(NO3)3·9H2O catalyst in the ethanol solution, heating of the ethanolic Fe(NO3)3·9H2O catalyst solution generated nitric acid (HNO3) due to decomposition, which damaged the fiber surfaces, resulting in an increase in the number of flaws and consequently a reduction in the tensile strength. Therefore, the tensile strength and Weibull modulus of CNT-grafted carbon fibers vary due to the combination of these effects and as a function of the catalyst concentration.

Naito, Kimiyoshi

2014-11-01

101

Mechanical properties of high-strength concrete  

NASA Astrophysics Data System (ADS)

This report summarizes an experimental program conducted to investigate production techniques and mechanical properties of high strength concrete in general and to provide recommendations for using these concretes in manufacturing precast/prestressed bridge girders. Test variables included total amount and composition of cementitious material (portland cement, fly ash, and silica fume), type and brand of cement, type of silica fume (dry densified and slurry), type and brand of high-range water-reducing admixture, type of aggregate, aggregate gradation, maximum aggregate size, and curing. Tests were conducted to determine the effects of these variables on changes in compressive strength and modulus of elasticity over time, splitting tensile strength, modulus of rupture, creep, shrinkage, and absorption potential (as an indirect indicator of permeability). Also investigated were the effects of test parameters such as mold size, mold material, and end condition. Over 6,300 specimens were cast from approximately 140 mixes over a period of 3 years.

Mokhtarzadeh, Alireza

102

Impact of a microwave curing process on tensile strength of selected carbon fiber composites  

Microsoft Academic Search

The traditional process for curing carbon fiber (CF) composites has been the autoclave system. A review of recent research indicates curing CF composites in a microwave oven has the potential for reducing processing time. The problem statement of the experimental study was that the impact of a microwave curing process on tensile strength of selected CF composite specimens was unknown.

Brian B. Balzer

2007-01-01

103

Strength of Tensile Loaded Graphite\\/Epoxy Laminates Containing Cracks, Open and Filled Holes  

Microsoft Academic Search

Most methods currently used for predicting tensile strength of composite laminates containing holes and cracks adopt a characteristic distance approach such as the Point Stress Criterion (PSC) or the Average Stress Criterion (ASC). These and similar ap proaches are attractive to designers since they are simple to apply. The limitation of such approaches, however, is that the characteristic distance is

Ingvar Eriksson; Carl-Gustaf Aronsson

1990-01-01

104

Microstructure and Tensile Properties of Wrought Al Alloy 5052 Produced by Rheo-Squeeze Casting  

NASA Astrophysics Data System (ADS)

The semisolid slurry of wrought Al alloy 5052 was prepared by the indirect ultrasonic vibration (IUV) method, in which the horn was vibrated under the outside of the metallic cup containing molten alloy, and then shaped by direct squeeze casting (SC). Spherical primary ?-Al particles were uniformly dispersed in the matrix and presented a bimodal distribution of grain sizes. The effects of rheo-squeeze casting (RSC) parameters such as squeeze pressure and solid fraction on the microstructure and tensile properties of the semisolid alloy were investigated. The results indicate that average diameters of the primary ?-Al particles decreased with the increase of squeeze pressure, while the tensile properties of the alloy increased. With the increase of solid fraction, the tensile strength increased first and then decreased, but the elongation decreased continuously. The best tensile properties were achieved when the slurry with a solid fraction of 0.17 solidified under 100 MPa. Compared to conventional squeeze casting, RSC process can offer the 5052 alloy better tensile strength and elongation, which were improved by 9.7 pct and 42.4 pct, respectively.

Lü, Shulin; Wu, Shusen; Wan, Li; An, Ping

2013-06-01

105

Wet-spinning of recombinant silk-elastin-like protein polymer fibers with high tensile strength and high deformability.  

PubMed

A recombinant silk-elastin-like protein copolymer SELP-47K containing tandemly repeated amino acid sequence blocks from silk, GAGAGS, and elastin, GVGVP, was fabricated into microdiameter fibers using a wet-spinning technique. Raman spectral analysis revealed the formation of antiparallel beta-sheet crystals of the silk-like blocks. Dry SELP-47K fibers display the dependence of mechanical properties such as Young's modulus on fiber diameter, suggesting more oriented and crystallized molecular chains in small-diameter fibers. Additionally, a brittle fracture mode was identified for dry fibers by SEM analysis of fracture surfaces. Hydration dramatically influenced the mechanical behavior of SELP-47K fibers. In contrast to the high tensile strength and limited strains to failure of dry fibers, fully hydrated SELP-47K fibers possessed strains to failure as high as 700%. Furthermore, upon chemical cross-linking, a tensile mechanical strength up to 20 MPa was achieved in hydrated fibers without compromising their high deformability. By combing the silk- and elastin-derived sequences into a single SELP-47K protein polymer, we demonstrated that protein fibers with high tensile strength and high deformability can be fabricated. PMID:19186950

Qiu, Weiguo; Teng, Weibing; Cappello, Joseph; Wu, Xiaoyi

2009-03-01

106

Tensile and transient burst properties of advanced ferritic/martensitic steel claddings after neutron irradiation  

NASA Astrophysics Data System (ADS)

The effects of fast neutron irradiation on tensile and transient burst properties of advanced ferritic/martensitic steel claddings for fast breeder reactors were investigated. Specimens were irradiated in the experimental fast reactor JOYO using the material irradiation rig at temperatures between 773 and 1013 K to fast neutron doses ranging from 11 to 102 dpa. The post-irradiation tensile and temperature-transient-to-burst tests were carried out. The results of mechanical tests showed that there was no significant degradation in tensile and transient burst strengths after neutron irradiation below 873 K. This was attributed to grain boundary strengthening caused by precipitates that preferentially formed on prior-austenite grain boundaries. Both strengths at neutron irradiation above about 903 K up to 102 dpa decreased due to radiation enhanced recovery of lath martensite structures and recrystallization.

Yano, Y.; Yoshitake, T.; Yamashita, S.; Akasaka, N.; Onose, S.; Takahashi, H.

2007-08-01

107

Effect of TiO2 Nanoparticles on Tensile Strength of Dental Acrylic Resins  

PubMed Central

Background and aims. Adding further fillers to dental resins may enhance their physical characteristics. The aim of this study was to evaluate the tensile strength of heat-curing acrylic resin reinforced by TiO2nanoparticles added into the resin matrix. Materials and methods. Commercially available TiO2 nanoparticles were obtained and characterized using X-ray diffrac-tion (XRD) and scanning electron microscopy (SEM) to determine their crystalline structure, particle size and morphology. TiO2-acrylic resin nanocomposite was prepared by mixing 0.5, 1 and 2 (wt%) of surface modified TiO2 nanoparticles in an amalgamator providing three groups of samples. Before curing, the obtained paste was packed into steel molds. After cur-ing, the specimens were removed from the molds. The tensile strength test samples were prepared according to ISO 1567. Results. Two crystalline phases were found in TiO2 nanoparticles including: (i) anatase as the major one, and (ii) rutile. The average particle size calculated according to the Scherrer equation was 20.4 nm, showing a normal size distribution. According to SEM images, the nanocomposite with 1wt% TiO2 nanoparticles had a better distribution compared to other groups. In addition, the group by 1wt% TiO2 exhibited higher tensile strength with a significant difference compared to other groups. ANOVA showed significant differences between the contents of TiO2 particles in acrylic resin (F = 22.19; P < 0.001). Conclusion. A considerable increase in tensile strength was observed with titania NPs reinforcement agents in 1wt% by weight. Further increase of TiO2 nanoparticles decreased the tensile strength. PMID:25587380

Shirkavand, Saeed; Moslehifard, Elnaz

2014-01-01

108

The effect of surface indications on the tensile properties of cast steel  

NASA Astrophysics Data System (ADS)

The objective of this thesis was to study the effect of surface indications on the tensile properties of cast steel. Four cast steel grades were selected for evaluation; these grades include three carbon and low alloy steels (110/80, 165/135, and Eglin) and one high alloy steel (CF8M). Using these steels, tensile specimens were produced, inspected via MT/PT, categorized by surface indications (as-cast or machined), and tested. Bars with natural surface indications were tensile tested and the properties recorded. The presence of a ? inch, ? inch, or ¼ inch flat-bottomed hole drilled through half the thickness mimicked a similar nonlinear worse-case scenario indication. The ¼ inch indication resulted in an ultimate tensile strength loss ranging from 21.5% to 36.0%, with the more ductile materials being impacted least. The percent elongation loss ranged from 38.5% to 69.9%, with the majority of the alloys showing an approximate 60 percent loss in elongation. The modulus decrease ranged from 2.9% to 17.5%. These results were modeled using ANSYS to observe capability in predicting a decrease in properties. The resulting decrease in properties matched the experimental data to an accuracy of 3+/-11%. The results provide a previously undocumented relationship between indication size and tensile properties.

Hamby, Jeff

109

Effects of bathing solution on tensile properties of the cornea.  

PubMed

The cornea is a transparent tissue with the major functions of protecting the inner contents of the eye and refracting incoming light. The biomechanical properties of the cornea strongly depend on the microstructure and composition of the stromal layer, a hydrated bio-gel. The uniaxial strip testing is a convenient and well-accepted experimental technique for characterizing corneal material parameters. It is known that the water content of specimens in this method depends on the osmolality of the bathing solution. The present study was designed to investigate the effects of different bathing solutions on uniaxial tensile material properties of the cornea. The tensile behavior of bovine corneal samples was measured in six different bathing solutions, i.e., hypertonic solution (12% NaCl solution), common preserving isotonic solutions (e.g., phosphate buffer saline, ophthalmic balanced salt solution, and 0.9% NaCl solution), hypotonic solution (distilled water), and neutral solution (mineral oil). It was observed that the bathing solution had significant influence on the tensile behavior of the corneal samples. In particular, the specimens tested in bathing solutions causing less swelling had significantly stiffer tensile properties. Furthermore, a simple mathematical model based on Voigt composite material model was developed to represent the measured solution-dependent tensile properties. The present study suggests that extra attention should be paid to corneal thickness (hydration) in uniaxial tensile experiments. It also provides important data on tensile properties of the cornea; such information could significantly contribute to improving the accuracy of numerical predictions of corneal biomechanics. PMID:24333541

Hatami-Marbini, Hamed; Rahimi, Abdolrasol

2014-03-01

110

Comparison of the Effect of two Denture Cleansers on Tensile bond Strength of a Denture Liner  

PubMed Central

Statement of Problem: One of the most clinical challenging issues in prosthodontics is debonding of soft liners from the denture base. Purpose: The aim of this study was to evaluate and compare tensile bond strength between soft liner and heat-cured acrylic resin when immersed in two different types of denture cleanser and distilled water, at different period of times. Materials and Method: In this experimental in vivo study, 238 heat-cured acrylic blocks were made. A soft liner was embedded between the acrylic blocks. Samples were divided into four groups: 17 samples were in the control group and were not soaked in any solution .The remaining samples were divided into 3 groups (Distilled water, Calgon and Fittydent). Each group was then subdivided into two subcategories, regarding the immersion time variable; 15 and 45 minutes. All samples were placed in tension force and tensile bond strength was recorded with the testing machine. One- way ANOVA and Tucky HSD post-hoc test were adopted to analyze the yielded data (?> 0.05). Results: Specimens which were immersed in two denture cleansers (Fittydent and Calgon) and in distilled water showed significant difference (p= 0.001) in bonding strength when compared to the control group. The subjects immersed in denture cleanser solutions and distilled water did not reveal any significant difference (p= 0.90). For all groups; most of the bonding failures (72%) were cohesive type. Conclusion: The effect of the denture cleansers and distilled water on the bond strength was not statistically different; however, the difference was significant between the immersed groups with the non-immersed group. Moreover, type of the denture cleanser did not show any effect on the tensile strength. The tensile strength increases with time of immersion. PMID:24724134

Farzin, M; Bahrani, F; Adelpour, E

2013-01-01

111

Microcracking and engineering properties of high-strength concrete  

NASA Astrophysics Data System (ADS)

An X-ray technique was used to study internal microcracking. Two classification systems were developed to analyze the microcracks: bond-mortar crack analysis and simple-combined crack analysis. Internal microcracks were observed at four strain levels. The observed microcracking mechanism is related to the failure mode in uniaxial compression. The results of the mechanical properties study are presented including data on compressive strength, strength gain with age, specimen size effect, static modulus of elasticity, Poisson's ratio, modulus of rupture, tensile splitting strength, unit weight, and drying effect on compressive and flexural strength of normal- and high-strength concretes.

Carrasquillo, R. L.

1980-02-01

112

Various conditioning methods for root canals influencing the tensile strength of titanium posts.  

PubMed

Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, manufacturers' instructions for this purpose differ widely from one another. The aim of this study was to compare the tensile bond strengths of passive, tapered, titanium root posts that were luted with four different resin composite cements (Compolute Aplicap, Flexi-Flow cem, Panavia 21 EX, Twinlook) in the root canals at three conditions, namely (i) no conditioning, (ii) etching with 37% phosphoric acid, and (iii) etching + bonding agent application. Panavia 21 EX was further tested after using the primer for the post-surface according to the manufacturer's recommendations. The posts luted with zinc phosphate cement (Tenet) acted as the control group. Following endodontic preparation of 140 intact anterior teeth with hand instruments, the post-spaces were prepared using the opening drills of the corresponding size of the posts. The samples were first stored in water at 37 degrees C for 24 h and then thermocycled (5000 cycles, 5-55 degrees C, 30 s). The tensile strength values were measured with the universal testing machine at a crosshead speed of 0.5 mm min(-1). The data were analysed statistically using anova and corrected with Scheffé test due to the significance levels (P < 0.05). The tensile bond strengths of the titanium posts after luting with various cements and thermocycling were affected by the conditioning systems used for the root canals. Tensile bond strengths were the highest with Flexi-Flow (475 +/- 78 N) followed in descending order by Panavia 21 EX (442 +/- 97 N), Twinlook (430 +/- 78 N) and Compolute Aplicap (352 +/- 76 N) after conditioning the root canal. The use of primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia 21 EX group (375 +/- 77 N) (P < 0.001). Tensile bond strengths obtained after luting the posts with zinc phosphate cement (414 +/- 102 N) were not significantly different (P < 0.05) than those of resin composite cements. Although the importance of conditioning the root canal was evident for Panavia 21 EX, it was not the case for the other luting cements tested. PMID:15369471

Schmage, P; Sohn, J; Nergiz, I; Ozcan, M

2004-09-01

113

Study of austenitic stainless steel welded with low alloy steel filler metal. [tensile and impact strength tests  

NASA Technical Reports Server (NTRS)

The tensile and impact strength properties of 316L stainless steel plate welded with low alloy steel filler metal were determined. Tests were conducted at room temperature and -100 F on standard test specimens machined from as-welded panels of various chemical compositions. No significant differences were found as the result of variations in percentage chemical composition on the impact and tensile test results. The weldments containing lower chromium and nickel as the result of dilution of parent metal from the use of the low alloy steel filler metal corroded more severely in a marine environment. The use of a protective finish, i.e., a nitrile-based paint containing aluminum powder, prevented the corrosive attack.

Burns, F. A.; Dyke, R. A., Jr.

1979-01-01

114

Influences of post-weld heat treatment on tensile properties of friction stir-welded AA6061 aluminum alloy joints  

SciTech Connect

This paper reports on studies of the influences of various post-weld heat treatment procedures on tensile properties of friction stir-welded AA6061 aluminum alloy joints. Rolled plates of 6-mm thick AA6061 aluminum alloy were used to fabricate the joints. Solution treatment, an artificial aging treatment and a combination of both were given to the welded joints. Tensile properties such as yield strength, tensile strength, elongation and joint efficiency were evaluated. Microstructures of the welded joints were analyzed using optical microscopy and transmission electron microscopy. A simple artificial aging treatment was found to be more beneficial than other treatment methods to enhance the tensile properties of the friction stir-welded AA6061 aluminum alloy joints.

Elangovan, K. [Department of Mechanical and Production Engineering, Annamalai University, Annamalai Nagar - 608 002, Tamil Nadu (India); Balasubramanian, V. [Centre for Materials Joining Research (CEMAJOR), Department of Manufacturing Engineering, Annamalai University, Annamalai Nagar - 608 002, Tamil Nadu (India)], E-mail: visvabalu@yahoo.com

2008-09-15

115

Developing an Empirical Relationship to Predict Tensile Strength of Friction Stir Welded AA2219 Aluminum Alloy  

NASA Astrophysics Data System (ADS)

AA2219 aluminum alloy (Al-Cu-Mn alloy) has gathered wide acceptance in the fabrication of lightweight structures requiring a high strength-to-weight ratio and good corrosion resistance. Friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a nonconsumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force, etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop an empirical relationship between FSW variables to predict tensile strength of the friction stir welded AA2219 aluminum alloy. To obtain the desired strength, it is essential to have a complete control over the relevant process parameters to maximize the tensile strength on which the quality of a weldment is based. Therefore, it is very important to select and control the welding process parameter for obtaining maximum strength. To achieve this various prediction methods such as response surface method (RSM), analysis of variance (ANOVA), Student’s t-test, coefficient of determination, etc., can be applied to define the desired output variables through developing mathematical models to specify the relationship between the output parameters and input variables. Four factors, five levels central composite design have been used to minimize number of experimental conditions. The developed mathematical relationship can be effectively used to predict the tensile strength of FSW joints of AA2219 aluminum alloy at 95% confidence level.

Elangovan, K.; Balasubramanian, V.; Babu, S.

2008-12-01

116

Hydrogen Embrittlement of a 1500-MPa Tensile Strength Level Steel with an Ultrafine Elongated Grain Structure  

NASA Astrophysics Data System (ADS)

A deformation of a tempered martensitic structure ( i.e., tempforming) at 773 K (500 °C) was applied to a 0.6 pct C-2 pct Si-1 pct Cr steel. The hydrogen embrittlement (HE) property of the tempformed (TF) steel was investigated by a slow strain rate test (SSRT) and an accelerated atmospheric corrosion test (AACT). Hydrogen content within the samples after SSRT and AACT was measured by thermal desorption spectrometry (TDS). The tempforming at 773 K (500 °C) using multipass caliber rolling with an accumulative are reduction of 76 pct resulted in the evolution of an ultrafine elongated grain (UFEG) structure with a strong <110>//rolling direction (RD) fiber deformation texture and a dispersion of spheroidized cementite particles. The SSRT of the pre-hydrogen-charged notched specimens and the AACT demonstrated that the TF sample had superior potential for HE resistance to the conventional quenched and tempered (QT) sample at a tensile strength of 1500 MPa. The TDS analysis also indicated that the hydrogen might be mainly trapped by reversible trapping sites such as grain boundaries and dislocations in the TF sample, and the hydrogen trapping states of the TF sample were similar to those of the QT sample. The QT sample exhibited hydrogen-induced intergranular fracture along the boundaries of coarse prior-austenite grains. In contrast, the hydrogen-induced cracking occurred in association with the UFEG structure in the TF sample, leading to the higher HE resistance of the TF sample.

Nie, Yihong; Kimura, Yuuji; Inoue, Tadanobu; Yin, Fuxing; Akiyama, Eiji; Tsuzaki, Kaneaki

2012-05-01

117

FE Analysis of Buckling Behavior Caused by Welding in Thin Plates of High Tensile Strength Steel  

NASA Astrophysics Data System (ADS)

The target of this study was to investigate buckling behavior during the entire welding process which consists of the heating and the cooling processes. For thin plate structures made of high tensile strength steel, not only residual buckling during or after cooling down but also transient buckling during heating may occur. The thermal elastic plastic FE analysis to investigate welding-induced buckling during the entire welding process is presented. Because of the high yield stress of high tensile strength steel, larger longitudinal compressive thermal stress is produced near the welding line compared with that in the case of carbon steel. Therefore, the plate may buckle due to thermal expansion, before the material nears yielding. During cooling down, the longitudinal compressive thermal stress close to the welding line disappears, and longitudinal tensile residual stress is produced due to contraction. Meanwhile, longitudinal compressive residual stress occurs far from the welding line to balance the tensile stress close to the welding line. This distribution of longitudinal residual stress would change the deformed dish shape of transient buckling into a saddle buckling type when the stress exceeds the critical buckling condition.

Wang, Jiangchao; Rashed, Sherif; Murakawa, Hidekazu

2014-09-01

118

FE Analysis of Buckling Behavior Caused by Welding in Thin Plates of High Tensile Strength Steel  

NASA Astrophysics Data System (ADS)

The target of this study was to investigate buckling behavior during the entire welding process which consists of the heating and the cooling processes. For thin plate structures made of high tensile strength steel, not only residual buckling during or after cooling down but also transient buckling during heating may occur. The thermal elastic plastic FE analysis to investigate welding-induced buckling during the entire welding process is presented. Because of the high yield stress of high tensile strength steel, larger longitudinal compressive thermal stress is produced near the welding line compared with that in the case of carbon steel. Therefore, the plate may buckle due to thermal expansion, before the material nears yielding. During cooling down, the longitudinal compressive thermal stress close to the welding line disappears, and longitudinal tensile residual stress is produced due to contraction. Meanwhile, longitudinal compressive residual stress occurs far from the welding line to balance the tensile stress close to the welding line. This distribution of longitudinal residual stress would change the deformed dish shape of transient buckling into a saddle buckling type when the stress exceeds the critical buckling condition.

Wang, Jiangchao; Rashed, Sherif; Murakawa, Hidekazu

2014-12-01

119

Laser solder repair technique for nerve anastomosis: temperatures required for optimal tensile strength  

NASA Astrophysics Data System (ADS)

Laser-assisted repair of nerves is often unsatisfactory and has a high failure rate. Two disadvantages of laser assisted procedures are low initial strength of the resulting anastomosis and thermal damage of tissue by laser heating. Temporary or permanent stay sutures are used and fluid solders have been proposed to increase the strength of the repair. These techniques, however, have their own disadvantages including foreign body reaction and difficulty of application. To address these problems solid protein solder strips have been developed for use in conjunction with a diode laser for nerve anastomosis. The protein helps to supplement the bond, especially in the acute healing phase up to five days post- operative. Indocyanine green dye is added to the protein solder to absorb a laser wavelength (approximately 800 nm) that is poorly absorbed by water and other bodily tissues. This reduces the collateral thermal damage typically associated with other laser techniques. An investigation of the feasibility of the laser-solder repair technique in terms of required laser irradiance, tensile strength of the repair, and solder and tissue temperature is reported here. The tensile strength of repaired nerves rose steadily with laser irradiance reaching a maximum of 105 plus or minus 10 N.cm-2 at 12.7 W.cm-2. When higher laser irradiances were used the tensile strength of the resulting bonds dropped. Histopathological analysis of the laser- soldered nerves, conducted immediately after surgery, showed the solder to have adhered well to the perineurial membrane, with minimal damage to the inner axons of the nerve. The maximum temperature reached at the solder surface and at the solder/nerve interface, measured using a non-contact fiber optic radiometer and thermocouple respectively, also rose steadily with laser irradiance. At 12.7 W.cm-2, the temperatures reached at the surface and at the interface were 85 plus or minus 4 and 68 plus or minus 4 degrees Celsius respectively. This study demonstrates the feasibility of the laser-solder repair technique for nerve anastomosis resulting in improved tensile strength. The welding temperature required to achieve optimal tensile strength has been identified.

McNally-Heintzelman, Karen M.; Dawes, Judith M.; Lauto, Antonio; Parker, Anthony E.; Owen, Earl R.; Piper, James A.

1998-01-01

120

Tensile Properties of Extruded Corn Protein Low-Density Polyethylene Films 1  

Microsoft Academic Search

Cereal Chem. 79(2):261-264 The strength of films extruded from powder blends of corn zein or corn gluten meal (CGM) with low-density polyethylene was investigated. Tensile strength, percent elongation at break, and elastic modulus of the extruded films were measured. The tensile strength decreased from 13 MPa to ?10.5 MPa with zein addition, while CGM addition resulted in tensile strength of

Thomas J. Herald; Ersel Obuz; Wesley W. Twombly; Kent D. Rausch

2002-01-01

121

A stereological analysis of aggregate grading and size effect on concrete tensile strength  

Microsoft Academic Search

One of the most important topics in solid mechanics is the study of the so-called size effects, whose importance has been widely recognised during the last decades. Size effects are particularly strong in quasi-brittle\\u000a (i.e., concrete-like) materials. In this paper we focus our attention on the tensile strength decrease associated with the\\u000a size of concrete structures. An original explanation of

Alberto Carpinteri; Pietro Cornetti; Simone Puzzi

2004-01-01

122

Tensile Bond Strength and SEM Evaluation of Caries-affected Dentin Using Dentin Adhesives  

Microsoft Academic Search

Tensile bond strength measurements are commonly used for the evaluation of dentin adhesive systems. Most tests are performed using extracted non-carious human or bovine dentin. However, the adhesion of resins to caries-affected dentin is still unclear. The objectives of this study were to test the hypothesis that bonding to caries-affected dentin is inferior to bonding to normal dentin, and that

M. Nakajima; H. Sano; M. F. Burrow; J. Tagami; M. Yoshiyama; S. Ebisu; B. Ciucchi; C. M. Russell; D. H. Pashley

1995-01-01

123

Tensile strength of simulated and welded butt joints in W-Cu composite sheet  

NASA Technical Reports Server (NTRS)

The weldability of W-Cu composite sheet was investigated using simulated and welded joints. The welded joints were produced in a vacuum hot press. Tensile test results showed that simulated joints can provide strength and failure mode data which can be used in joint design for actual weldments. Although all of the welded joints had flaws, a number of these joints were as strong as the W-Cu composite base material.

Moore, Thomas J.; Watson, Gordon K.

1994-01-01

124

Effect of laser welding on the titanium ceramic tensile bond strength  

PubMed Central

Titanium reacts strongly with elements, mainly oxygen at high temperature. The high temperature of titanium laser welding modifies the surface, and may interfere on the metal-ceramic tensile bond strength. Objective The influence of laser welding on the titanium-ceramic bonding has not yet been established. The purpose of this in vitro study was to analyze the influence of laser welding applied to commercially pure titanium (CpTi) substructure on the bond strength of commercial ceramic. The influence of airborne particle abrasion (Al2O3) conditions was also studied. Material and Methods Forty CpTi cylindrical rods (3 mm x 60 mm) were cast and divided into 2 groups: with laser welding (L) and without laser welding (WL). Each group was divided in 4 subgroups, according to the size of the particles used in airborne particle abrasion: A - Al2O3 (250 µm); B - Al2O3 (180 µm); C - Al2O3 (110 µm); D - Al2O3 (50 µm). Ceramic rings were fused around the CpTi rods. Specimens were invested and their tensile strength was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 200 kgf load cell. Statistical analysis was carried out with analysis of variance and compared using the independent t test (p?0.05). Results Significant differences were found among all subgroups (p<0.05). The highest and the lowest bond strength means were recorded in subgroups WLC (52.62 MPa) and LD (24.02 MPa), respectively. Conclusion Airborne particle abrasion yielded significantly lower bond strength as the Al2O3 particle size decreased. Mechanical retention decreased in the laser-welded specimens, i.e. the metal-ceramic tensile bond strength was lower. PMID:21956585

GALO, Rodrigo; RIBEIRO, Ricardo Faria; RODRIGUES, Renata Cristina Silveira; PAGNANO, Valéria de Oliveira; de MATTOS, Maria da Glória Chiarello

2011-01-01

125

The Effect of Teucrium Polium Hney on the Wound Healing and Tensile Strength in Rat  

PubMed Central

Objective(s) Wound healing represents a dynamic physiological process influenced by many factors. The aim of the present study was to evaluate the effects of Teucrium polium honey on the wound healing and tensile strength in rat. Materials and Methods Thirty-six Sprague-Dawley rats were randomly divided into four equal (n= 9) treatment and control groups. Two full-thickness wounds were made over the dorsal thoracic region according to the incision and excision models. Animals were treated with topical Teucrium polium honey twice a day post surgery until complete healing was achieved. Histopathology and tensiometry were then studied. Results The wound healing process occurred faster in the incision model than excision ones (P< 0.05). Teucrium polium honey promoted wound contraction, closure time and tensile strength (P< 0.05). Histopathological study also showed relative epithelial proliferation, improved angiogenesis granulation, and fibrous connective tissue in Teucrium polium honey treated animals. Conclusion The present study demonstrates that Teucrium polium honey can accelerate wound healing as well as tensile strength in rat skin wounds. PMID:23493667

Alizadeh, Ali Mohammad; Sohanaki, Hamid; Khaniki, Mahmod; Mohaghgheghi, Mohammad Ali; Ghmami, Giti; Mosavi, Maryamsadat

2011-01-01

126

Tensile properties of rat anterior cruciate ligament in collagen induced arthritis  

PubMed Central

OBJECTIVES—To investigate the effects of collagen induced arthritis (CIA) on the tensile properties of rat anterior cruciate ligament (ACL).?METHODS—The tensile strength, bone mineral density (BMD), and histology of ACL units from rats with CIA were investigated.?RESULTS—The tensile strength of the ACL unit was significantly lower in the rats with CIA at 10 weeks after immunisation (ultimate failure load, 74.9% of the control; stiffness, 62.0% of the control). The major mode of failure was femoral avulsion, and the BMD was significantly lower in the rats with CIA. A histological examination of the ligament insertion in rats with CIA showed resorption of the cortical bone beneath the ACL insertion and an enlarged mineralised fibrocartilage zone.?CONCLUSIONS—These findings indicate that the decrease in tensile strength of ACL units correlated with histological changes in the ligament-bone attachment, such as bone resorption beneath the ligament insertion site and an enlargement of the mineralised fibrocartilage zone.?? PMID:11247872

Nawata, K; Enokida, M; Yamasaki, D; Minamizaki, T; Hagino, H; Morio, Y; Teshima, R

2001-01-01

127

Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers  

NASA Astrophysics Data System (ADS)

The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4'-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.

Naito, Kimiyoshi

2014-09-01

128

Parameters of tensile strength, elongation, and tenacity of 70mm IIaO spectroscopic film  

NASA Technical Reports Server (NTRS)

The 70mm IIaO spectroscopic film was tested to determine its tensile strength, elongation, and breaking strength, using an Instron (strength and compression) 4201 Test Instrument. These data provide information leading to the upper and lower limits of the above parameters for 70mm IIaO spectroscopic film. This film will be developed by a commercial developing machine after the Ultraviolet Telescope Space Shuttle Mission returns to the Earth in the early 1990's; thus, it is necessary to understand these force parameters. Several test strips of approximately 200mm in length were used. The results indicate that when a stress load of 100 kg was applied, the film elongated approximately 1.06mm and the break strength was 19.45 kilograms.

Hammond, Ernest C., Jr.; Peters, Kevin A.

1989-01-01

129

Optimization of laser beam welding process parameters to attain maximum tensile strength in AZ31B magnesium alloy  

NASA Astrophysics Data System (ADS)

An empirical relationship is developed to predict tensile strength of the laser beam welded AZ31B magnesium alloy by incorporating process parameters such as laser power, welding speed and focal position. The experiments were conducted based on a three factor, three level, central composite face centered design matrix with full replications technique. The empirical relationship can be used to predict the tensile strength of laser beam welded AZ31B magnesium alloy joints at 95% confidence level. The results indicate that the welding speed has the greatest influence on tensile strength, followed by laser power and focal position.

Padmanaban, G.; Balasubramanian, V.

2010-11-01

130

Structure-tensile properties of polyurethanes  

Microsoft Academic Search

A series of hydroxyl terminated polybutadiene-(HTPB) based polyurethanes (PUs) were synthesized by solution polymerization with different types of diisocyanates, hard segment contents, NCOOH ratio and polymerization methods. Spectroscopic and stress-strain studies were carried out to elucidate the structure-property relationships existing in these polymers. It was found that the binding of the hard segment and the flexibility of soft segments had

Shih-Liang Huang; Juin-Yih Lai

1997-01-01

131

The tensile strength of black bear (Ursus americanus) cortical bone is not compromised with aging despite annual periods of hibernation.  

PubMed

Black bears (Ursus americanus) may not develop disuse osteoporosis during long periods of disuse (i.e. hibernation) because they may be able to maintain bone formation. Previously, we found that cortical bone bending strength was not compromised with age in black bears' tibias, despite annual periods of disuse. Here we showed that cortical bone tensile strength (166-198MPa) also does not decrease with age (2-14 years) in black bear tibias. There were also no significant age-related changes in cortical bone porosity in black bear tibias. It is likely that the ability of black bears to maintain bone formation during hibernation keeps bone porosity low (2.3-8.6%) with aging, notwithstanding annual periods of disuse. This low porosity likely preserves ultimate stress with aging. Female bears give birth and nurse during hibernation; however, we found no significant differences between male and female tensile material properties, mineral content, or porosity. Our findings support the idea that black bears, which hibernate 5-7 months annually, have evolved biological mechanisms to mitigate the adverse effects of disuse on bone porosity and strength. PMID:16115638

Harvey, Kristin B; Drummer, Thomas D; Donahue, Seth W

2005-11-01

132

Identification of anisotropic tensile strength of cortical bone using Brazilian test.  

PubMed

For a proper analysis of cortical bone behaviour, it is essential to take into account both the elastic stiffness and the failure criteria. While ultrasound methods allow complete identification of the elastic orthotropic coefficients, tests used to characterise the various failure mechanisms and to identify the brittle tensile strength in all directions are currently inadequate. In the present work we propose the Brazilian test as a complement to conventional tensile tests. In fact, this experimental technique, rarely employed in the biomechanics field, has the potential to provide an accurate description of the anisotropic strength of cortical bone. Additionally, it allows us to assess the scale influence on failure behaviour which may be attributed to an intrinsic length in correlation with the cortical bone microstructure. In order to correctly set up the Brazilian test, several aspects such as the machining, the geometrical parameters of the specimen and the loading conditions were determined. The finite element method was used to evaluate the maximal tensile stress at the centre of a 2D anisotropic elastic specimen as a simple function of the loading. To validate the protocol, the Brazilian test was carried out on 29 cortical bovine cylindrical specimens with diameters ranging from 10mm to 4mm. PMID:25051151

Allena, Rachele; Cluzel, Christophe

2014-10-01

133

Tensile bond strength of four denture resins to porcelain teeth with different surface treatment  

PubMed Central

PURPOSE This study evaluated the bond strength between porcelain denture teeth (Bioblend 43D) and four different polymerized denture resins (Lucitone 199, Palapress, Acron MC, Triad) with and without a bonding agent and after four different types of surface treatment (polished, HF etched, sandblasted, air-abraded). MATERIALS AND METHODS Central incisor porcelain denture teeth were divided into 32 groups of 5 each. Tensile bond strength (MPa) was determined using a testing machine at crosshead speed of 0.5 mm/min. Mean and standard deviation are listed. Data were analyzed by two-way ANOVA. Means were compared by Tukey-Kramer intervals at 0.05 significance level. RESULTS All surface treatment increased bond strength compared to polished surface and the highest bond strength was found with Palapress resin with etched porcelain surface (8.1 MPa). Bonding agent improved the bond strength of all denture resins to porcelain teeth. Superior bonding was found with Palapress and air-abraded porcelain (39 MPa). CONCLUSION Resins with different curing methods affect the bond strength of porcelain teeth to denture bases. Superior bonding was found with auto-polymerized resin (Palapress). Application of ceramic primer and bonding agent to porcelain teeth with and without surface treatment will improve the bond strength of all denture resins to porcelain teeth. PMID:24353880

Powers, John

2013-01-01

134

Tensile Properties and Deformation Characteristics of a Ni-Fe-Base Superalloy for Steam Boiler Applications  

NASA Astrophysics Data System (ADS)

Ni-Fe-base superalloys due to their good manufacturability and low cost are the proper candidates for boiler materials in advanced power plants. The major concerns with Ni-Fe-base superalloys are the insufficient mechanical properties at elevated temperatures. In this paper, tensile properties, deformation, and fracture characteristics of a Ni-Fe-base superalloy primarily strengthened by ?' precipitates have been investigated from room temperature to 1073 K (800 °C). The results showed a gradual decrease in the strength up to about 973 K (700 °C) followed by a rapid drop above this temperature and a ductility minimum at around 973 K (700 °C). The fracture surfaces were studied using scanning electron microscopy and the deformation mechanisms were determined by the observation of deformed microstructures using transmission electron microscopy. An attempt has been made to correlate the tensile properties and fracture characteristics at different temperatures with the observed deformation mechanisms.

Zhong, Zhihong; Gu, Yuefeng; Yuan, Yong; Shi, Zhan

2014-01-01

135

Elastic constants and tensile properties of Al2OC by density functional calculations  

NASA Astrophysics Data System (ADS)

Al2OC is a compound that forms as a nanoscale grain-boundary crystalline film in silicon carbide ceramics, and is responsible for imparting high low-temperature toughness and high-temperature creep strength in these materials. The elastic properties and ultimate strengths properties of Al2OC are determined from first-principles calculations. The crystal structure of Al2OC was approximated by an optimized model based on the wurtzite structure. The full set of single-crystal elastic stiffness cij was calculated, from which the polycrystalline elastic constants were obtained by using the Voigt-Reuss-Hill averaging scheme. The tensile properties and the ideal strength in [001] direction of Al2OC were also computed and compared to those of SiC , where it was found that indeed, Al2OC is the weaker and more brittle phase, supporting fracture mechanics expectations for SiC containing Al2OC -type intergranular films.

Yu, R.; Zhang, X. F.; de Jonghe, L. C.; Ritchie, R. O.

2007-03-01

136

Effect of the concrete compressive strength and tensile reinforcement ratio on the flexural behavior of fibrous concrete beams  

Microsoft Academic Search

Twenty seven reinforced concrete beams were tested to study the effects of steel fibers, longitudinal tensile reinforcement ratio and concrete compressive strength on the flexural behavior of reinforced concrete beams.Concrete compressive strengths of 49, 79 and 102 MPa and tensile reinforcement ratios of 1.18, 1.77 and 2.37% were used. The fiber contents were 0.0, 0.5 and 1.0% by volume. The

Samir A Ashour; Faisal F Wafa; Mohmd I Kamal

2000-01-01

137

Low-velocity impact characteristics and residual tensile strength of carbon fiber composite lattice core sandwich structures  

Microsoft Academic Search

In this paper, low-velocity impact characteristics and residual tensile strength of carbon fiber composite lattice core sandwich structures are investigated by experimentally and numerically. Low-velocity impact tests and residual tensile strength tests are performed using an instrumented drop-weight machine (Instron 9250HV) and static test machine (Instron 5569), respectively. The FE (finite element) software, ABAQUS\\/Explicit is employed to simulate low-velocity impact

Bing Wang; Lin-Zhi Wu; Li Ma; Ji-Cai Feng

2011-01-01

138

Effect of Welding and Post-weld Heat Treatment on Tensile Properties of Nimonic 263 at Room and Elevated Temperatures  

NASA Astrophysics Data System (ADS)

Nimonic 263 has been developed for the improved ductility in welded assemblies and is a candidate material for gas turbine combustor and transition pieces along with its good weldability and mechanical properties at room and elevated temperatures. In this study, the tensile behavior of an as-welded Nimonic 263 specimen at room temperature and 1053 K (780 °C) was examined in conjunction with microstructural evolution during welding and postweld heat treatment (PWHT). With the welding and the PWHT, the yield strength (YS), ultimate tensile strength (UTS), and tensile elongation of Nimonic 263 varied in a complex manner. It was observed that the PWHT of resolutionization at 1423 K (1150 °C) for 2 hours gave the highest YS and UTS values, whereas the tensile elongation was the lowest, at both testing temperatures. With increasing resolutionization time, the YS and UTS tended to decrease along with the increase in tensile ductility. The tensile behaviors of as-welded Nimonic 263 specimens was affected by several factors, including grain size, residual stress, possible microsegregation of ?' forming elements, a tendency for interdendritic or intergranular fracture and a morphological change in both M23C6 and MC type carbides, depending on the testing temperature and the PWHT. The complex changes in tensile properties of Nimonic 263 with welding and PWHT at room temperature and 1053 K (780 °C) were discussed based on the micrographic and fractographic observations.

Jeon, Minwoo; Lee, Jae-Hyun; Woo, Ta Kwan; Kim, Sangshik

2011-04-01

139

Tensile Strength and Microstructure of Al2O3-ZrO2 Hypo-Eutectic Fibers Studied  

NASA Technical Reports Server (NTRS)

Oxide eutectics offer high-temperature strength retention and creep resistance in oxidizing environments. Al2O3-ZrO2 eutectic strengths have been studied since the 1970's. Directionally solidified oxide eutectics exhibit improved resistance to slow crack growth and excellent strength retention at high temperatures up to 1400 C. Materials studied typically contain Y2O3 to metastably retain the high-temperature cubic and tetragonal polymorphs at room temperature. Al2O3-ZrO2 is of fundamental interest for creep studies because it combines a creep-resistant material, Al2O3, with a very low creep resistance material, ZrO2. Results on mechanical properties and microstructures of these materials will be used to define compositions for creep testing in future work. Substantial variations from the eutectic alumina to zirconia ratio can be tolerated without a loss in room-temperature strength. The effect of increasing Y2O3 addition on the room-temperature tensile strength of an Al2O3-ZrO2 material containing excess Al2O3 was examined at the NASA Glenn Research Center, where the materials were grown using Glenn's world-class laser growth facilities.

Farmer, Serene C.; Sayir, Ali

2001-01-01

140

Effect of Strain Rate on Tensile Properties of Carbon Fiber Epoxy-Impregnated Bundle Composite  

NASA Astrophysics Data System (ADS)

The tensile tests for high tensile strength polyacrylonitrile (PAN)-based (T1000GB) carbon fiber epoxy-impregnated bundle composite at various strain rates ranging from 3.33 × 10-5 to 6.0 × 102 s-1 (various crosshead speeds ranging from 8.33 × 10-7 to 1.5 × 101 m/s) were investigated. The statistical distributions of the tensile strength were also evaluated. The results clearly demonstrated that the tensile strength of bundle composite slightly increased with an increase in the strain rate (crosshead speed) and the Weibull modulus of tensile strength for the bundle composite decreased with an increase in the strain rate (crosshead speed), there is a linear relation between the Weibull modulus and the average tensile strength on log-log scale.

Naito, Kimiyoshi

2014-03-01

141

Scale-up model describing the impact of lubrication on tablet tensile strength.  

PubMed

Lubrication of 2:1 and 1:1 blends of microcrystalline cellulose and spray-dried lactose or dibasic calcium phosphate (DCP) with 0.33% or 1% magnesium stearate, as model free-flowing pharmaceutical formulations, was performed in rotary drum blenders. Blender process parameters examined in this study included type (Bin, V, and Turbula), volume (0.75-Quart to 200-L), fraction of headspace in the blender after the blend is loaded (30-70%), speed (6-202 rpm), and time (up to 225 min). Based on analysis of the experimental data, the following model for the impact of the lubrication process on tablet tensile strength at 0.85 solid fraction, TS(SF=0.85), was obtained, TS(SF=0.85)=TS(SF=0.85,0) [?exp(-?×V(1/3)×F(headspace)×r)+(1-?)], where V is blender volume, F(headspace) is the headspace fraction, r is the number of revolutions (i.e. speed × time), TS(SF=0.85,0) is the initial tensile strength of the blend, ? is the sensitivity of the blend to lubrication, and ? is the lubrication rate constant of the formulation. This model can be used to maintain tensile strength during scale-up, by ensuring that (V(1/3)F(headspace)r)(1)=(V(1/3)F(headspace)r)(2). The model also suggests that formulations with DCP are less sensitive to lubrication and more slowly lubricated than formulations with spray-dried lactose (i.e. smaller ? and ? values). PMID:20667504

Kushner, Joseph; Moore, Francis

2010-10-31

142

Morphine enhances tissue content of collagen and increases wound tensile strength  

Microsoft Academic Search

Purpose  Morphine is a commonly prescribed analgesic for wound pain. Previous studies have shown that morphine enhances accumulation\\u000a of collagen in cultured fibroblasts. Because fibroblasts are important for the remodeling of connective tissue in incisional\\u000a wound, this study investigates the biological effects of morphine on cutaneous collagen content and wound tensile strength.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  A full-thickness incisional wound (2 cm in length) was created

Pei-Jung Chang; Meng-Yi Chen; Yu-Sheng Huang; Chou-Hwei Lee; Chien-Chi Huang; Chen-Fuh Lam; Yu-Chuan Tsai

2010-01-01

143

Tensile properties of cellulose fiber reinforced hydroxypropylcellulose films  

Microsoft Academic Search

The tensile properties of cross-linked and uncross-linked composite films (thickness 20-35 m) prepared from Hydroxypropylcellulose (HPC) with incorporation of microcrystalline cellulose fibers (Avicel) were studied. The concentration of fibers in the composites ranged from 0 to 30 w\\/w% and cross-linked composites were obtained by the reaction of HPC-Avicel mixtures with 1,4-butyldiisocyanate. It was demonstrated that the inclusion of fibers in

J. P. Borges; M. H. Godinho; A. F. Martins; D. F. Stamatialis; M. N. De Pinho; M. N. Belgacem

2004-01-01

144

An experimental investigation on the tensile moduli and strengths of graphite/epoxy laminates  

NASA Technical Reports Server (NTRS)

The results of a series of tensile tests on some graphite/epoxy laminates, at rates varying from 0.002 to 2 in./min are examined. The loads were applied at various angles to the fiber directions in each case. The rate-dependent behavior of the stress-strain response is assessed. Evidence is presented to indicate that failure first occurs on inner plies, and that, in some cases, moduli increase with increasing stress (or strain) level. Lamination theory is used to predict the moduli, and comparisons with experiment are given. This theory is also used in conjunction with three failure theories to predict ultimate strengths (with varying degrees of success). Further, two approaches to ply unloading after first-ply failure are used and discussed. One is a standard method found in the literature while the other is a proposed 'strength-of-materials' type of technique which is computationally much simpler.

Yeow, Y. T.; Brinson, H. F.

1977-01-01

145

Tensile properties and fracture reliability of a glass-coated Co-based amorphous microwire  

NASA Astrophysics Data System (ADS)

Co68.15Fe4.35Si12.25B15.25 (at%) amorphous microwires with a smooth surface and a circular cross-section were fabricated by the glass-coated melt spinning method. Their mechanical properties were evaluated through tensile tests of the glass-coated amorphous microwires, and their fracture reliability was estimated using two- and three-parameter Weibull analysis. X-ray diffraction and transmission electron microscopy results showed that these glass-coated Co-based microwires were mostly amorphous. The coated Co-based microwires exhibit a tensile strength of 1145 to 2457 MPa, with a mean value of 1727 MPa and a variance of 445 MPa. Weibull statistical analysis showed that the tensile two-parameter Weibull modulus of the amorphous microwires is 4.16 and the three-parameter Weibull modulus is 1.61 with a threshold value as high as 942 MPa. These results indicate that the fabricated microwires exhibit good tensile properties and fracture reliability, and thus appear to be good candidates for electronics reliability engineering applications.

Wang, Xiao-dong; Wang, Huan; Shen, Hong-xian; Qin, Fa-xiang; Xing, Da-wei; Liu, Jing-shun; Chen, Dong-ming; Sun, Jian-fei

2014-06-01

146

Microstructure and tensile properties of squeeze cast magnesium alloy AM50  

NASA Astrophysics Data System (ADS)

High-pressure die cast magnesium alloy AM50 is currently used extensively in large and complex shaped thin-wall automotive components. For further expansion of the alloy usage in automobiles, novelmanufacturing processes need to be developed. In this study, squeeze casting of AM50 alloy with a relatively thick cross section was carried out using a hydraulic press with an applied pressure of 70 MPa. Microstructure and mechanical properties of the squeeze cast AM50 with a cross-section thickness of 10 mm were characterized in comparison with the die cast counterpart. The squeeze cast AM50 alloy exhibits virtually no porosity in the microstructure as evaluated by both optical microscopy and the density measurement technique. The results of tensile testing indicate the improved tensile properties, specifically ultimate tensile strength and elongation, for the squeeze cast samples over the conventional high-pressure die cast parts. The analysis of tensile behavior show that the strain-hardening rate during the plastic deformation of the squeeze cast specimens is constantly higher than that of the die cast specimens. The scanning electron microscopy fractography evidently reveals the ductile fracture features of the squeeze cast alloy AM50.

Zhou, Ming; Hu, Henry; Li, Naiyi; Lo, Jason

2005-08-01

147

Tensile Properties of Under-Matched Weld Joints for 950 MPa Steel.  

NASA Astrophysics Data System (ADS)

In welding of 950 MPa-class high tensile strength steel, preheating is crucial in order to avoid cold cracks, which, however, eventually increases welding deformations. One way to decrease welding deformations is lowering preheating temperature by using under-matched weld metal. Toyota and others clarify that although breaking elongation can decrease due to plastic constraint effect under certain conditions, static tensile of under-matched weld joints is comparable to that of base metal. However, there has still been no report about joint static tensile of under-matched weld joints applied to 950 MPa-class high tensile strength steel. In this study, we aim to research tensile strength and fatigue strength of under-matched weld joints applied to 950 MPa-class high tensile steel.

Yamamoto, Kouji; Arakawa, Toshiaki; Akazawa, Nobuki; Yamamoto, Kousei; Matsuo, Hiroki; Nakagara, Kiyoyuki; Suita, Yoshikazu

148

The impact of polymerization method on tensile bond strength between denture base and acrylic teeth.  

PubMed

Failure of the bond between acrylic teeth and the denture base resin interface is one of the major concern in prosthodontics. The new generation of denture bases that utilize alternate polymerization methods are being introduced in the market. The aim of the study is to evaluate the influence of polymerization methods on bonding quality between the denture base and artificial teeth. Sixty test specimens were prepared (20 in each group) and were polymerized using heat, microwave and visible light curing. The tensile strength was recorded for each of the samples, and the results were analyzed statistically. The light-activated Eclipse™ System showed the highest tensile strength, followed by heat curing. The microwave-cured samples exhibited the least bonding to the acrylic teeth. Within the limitations of this study, it can be concluded that the new generation of light-cured denture bases showed significantly better bonding to acrylic teeth and can be used as an alternative to the conventional heat-polymerized denture base. PMID:25307813

Hashem, Mohamed; Binmgren, Mohammed A; Alsaleem, Samah O; Vellappally, Sajith; Assery, Mansour K; Sukumaran, Anil

2014-01-01

149

Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes  

PubMed Central

Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO) and differential scanning calorimetry (DSC) separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of ? and ? phases, the overall membranes were predominantly ? phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of ? and ? phases, the overall membranes were predominantly ? phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 °C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites. PMID:24957064

Liu, Jie; Lu, Xiaolong; Wu, Chunrui

2013-01-01

150

Investigating the Effect of Cyclic Loading on the Indirect Tensile Strength of Rocks  

NASA Astrophysics Data System (ADS)

This paper presents the results of laboratory experiments during the investigation of the stress-strain characteristics of Brisbane tuff disc specimens under diametral compressive cyclic loading. Two different cyclic loading methods were used: namely, sinusoidal cyclic loading and cyclic loading with increasing mean level. The first method applied the S- N curve approach to the indirect tensile strength (ITS) of rock specimens for the first time in the literature, and the second method investigated the effect of increasing cyclic loading on the ITS of rock specimens. The ITS of Brisbane tuff disc specimens was measured using the Brazilian tensile strength test. The reduction in ITS was found to be 33% with sinusoidal loading tests, whereas increasing cyclic loading caused a maximum reduction of 37%. It is believed that the fracturing under cyclic loading starts at contact points between strong grains and weak matrices, and that contact points at grain boundaries are the regions of stress concentration (i.e., indenters). Transgranular cracks emanate from these regions and intergranular cracks sometimes pass through the contact points. Once cracking begins, there is a steady progression of damage and a general `loosening' of the rock, which is a precursor to the formation of intergranular cracks.

Erarslan, N.; Williams, D. J.

2012-05-01

151

Effect of Cold Work on Tensile Properties During Annealing Process for Pure Commercial Aluminum (AA 1070 Alloy)  

Microsoft Academic Search

The behavior of non-heat-treatable aluminum alloy in annealing process depends mainly on chemical composition and amount of cold work (strain) retained in the texture. This article discusses the effect of cold work on tensile properties during annealing process. The article discusses the steepness and magnitude of the decline in yield strength and the critical temperature, which has the greatest effect

Raed M. Al Qassab

2007-01-01

152

Influence of macrostructure on tensile properties of multipass SAW C-Mn steel deposits  

NASA Astrophysics Data System (ADS)

Blocks of 'all weld' metal were prepared by a multipass submerged arc process, using a C-Mn filler wire, at different welding currents and speeds by keeping the arc voltage constant. The variation in welding parameters was found to alter the macrostructure primarily by influencing its co-axial dendrite content. The chemical composition and hardness of the dendritic and the heat affected regions were affected little by the welding parameters. A dendrite content up to 37%, had no significant effect on the tensile properties. However an increase in it beyond 37% was found to enhance the UTS and YS and reduce percent elongation. The tensile strength was found to be a maximum in the L orientation and a minimum in the S direction. The use of post-weld heat treatment (PWHT) at 873 K caused spheroidization of cementite there by somewhat reducing the hardness and strength. The treatment while not affecting the basic dendritic morphology reduced the observed difference in tensile properties along the L, T and S directions. Implications of the data vis-a-vis industrial applications have been discussed.

Yongyuth, P.; Ghosh, P. K.; Gupta, P. C.; Patwardhan, A. K.; Prakash, Satya

1993-06-01

153

Relationship between apposition pressure during welding and tensile strength of the acute weld  

NASA Astrophysics Data System (ADS)

Dye-assisted photothermal welding is a technique used to close wounds by thermally cross-linking collagen across apposed tissue edges. For a successful weld, not only do laser parameters have to be optimized, but also apposition of the incision has to be consistent and controlled. The objective of this study was to quantify the relationship between the applied apposition pressure (i.e., the compressive force holding the wound closed during the welding procedure divided by the area of the skin-to-skin interface) and the tensile strength of the wound following the welding procedure. By using a clamping device made of two complementary pieces, each 3 cm wide with a row of 10 equally spaced blunt wire mesh tips, the apposition pressure along a 2-cm-long incision in each albino guinea pig was quantified using a 127-micrometers -thick load cell and varied from 0-1.8 kgf/cm2. A continuous wave, Nd:YAG laser emitting 10.0 W of 1.06-micrometers radiation from a 600-micrometers -diameter fiber irradiating a 5-mm-diameter spot size was scanned across the incision in order to deliver 300 J of total energy. As the apposition pressure of the incisions was increased, the resulting tensile strength of welded skin increased in a sigmoidal manner. For this welding technique, an apposition pressure of at least 1.2 kgf/cm2 is necessary to obtain maximum weld strength of the skin (2.56+/- 0.36 kg/cm2).

Wu, Paul J.; Walsh, Joseph T., Jr.

2001-05-01

154

Effect of current pulsing on tensile properties of titanium alloy  

Microsoft Academic Search

Titanium and its alloys have been considered as one of the best engineering metals for industrial applications. This is due to the excellent combination of properties such as elevated strength to weight ratio, high toughness, excellent resistance to corrosion and good fatigue properties make them attractive for many industrial applications. Recently, considerable research has been performed on pulsed current gas

V. Balasubramanian; V. Jayabalan; M. Balasubramanian

2008-01-01

155

Tensile Property of Al-Mg-Sc-Zr Alloy at Cryogenic Temperature  

SciTech Connect

The tensile property and fracture characteristic of Al-Mg-Sc-Zr alloy have been investigated at 77 K, 123 K, 173 K, 223 K and 300 K respectively. Both the strength and elongation improved with decreasing temperature from 300 K to 77 K, particularly between 123 K and 77 K. However, the reduction of area exhibited a maximum at around 173 K. The fractographs of tensile specimens show a completely dimple-type ductile mode of fracture at 77 K and mixed type of fracture at 300 K, and the primary Al3(Sc,Zr) and Al6(Mn,Fe) phases are responsible for void and crack initiation at their interface with the matrix at cryogenic temperature.

Zhao, W. T.; Yan, D. S.; Li, X. Y.; Rong, L. J.; Li, Y. Y. [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

2006-03-31

156

Mechanical properties of individual InAs nanowires studied by tensile tests  

SciTech Connect

Mechanical properties of individual InAs nanowires (NWs) synthesized by metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) methods are studied by in-situ tensile tests in a scanning electron microscope and their fracture strength and Young's modulus are obtained. The two types of NWs both exhibit brittle fracture with a maximum elastic strain up to ?10%. Their fracture strength distributes in a similar range of ?2–5?GPa with a general trend of increasing with NW volume decrease, which is well described by Weibull statistic with a smaller Weibull modulus and a higher characteristic strength for MOCVD NWs. Young's modulus is determined to be 16–78?GPa with an average value of 45?GPa and no dependence on NW diameter for MOCVD NWs and 34–79?GPa with an average value of 58?GPa for MBE NWs.

Li, X.; Wei, X. L., E-mail: weixl@pku.edu.cn, E-mail: qingchen@pku.edu.cn; Xu, T. T.; Ning, Z. Y.; Shu, J. P.; Chen, Q., E-mail: weixl@pku.edu.cn, E-mail: qingchen@pku.edu.cn [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Wang, X. Y.; Pan, D.; Zhao, J. H.; Yang, T. [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)] [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2014-03-10

157

Mechanical properties of individual InAs nanowires studied by tensile tests  

NASA Astrophysics Data System (ADS)

Mechanical properties of individual InAs nanowires (NWs) synthesized by metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) methods are studied by in-situ tensile tests in a scanning electron microscope and their fracture strength and Young's modulus are obtained. The two types of NWs both exhibit brittle fracture with a maximum elastic strain up to ˜10%. Their fracture strength distributes in a similar range of ˜2-5 GPa with a general trend of increasing with NW volume decrease, which is well described by Weibull statistic with a smaller Weibull modulus and a higher characteristic strength for MOCVD NWs. Young's modulus is determined to be 16-78 GPa with an average value of 45 GPa and no dependence on NW diameter for MOCVD NWs and 34-79 GPa with an average value of 58 GPa for MBE NWs.

Li, X.; Wei, X. L.; Xu, T. T.; Ning, Z. Y.; Shu, J. P.; Wang, X. Y.; Pan, D.; Zhao, J. H.; Yang, T.; Chen, Q.

2014-03-01

158

Where to fix in rejuvenation surgeries?: tensile strength of the periosteum.  

PubMed

The aim of this study is to elucidate the tensile strength of the periosteum relating to facial rejuvenation surgeries.Twelve hemifaces of 6 formalin-fixed Korean adult cadavers were used. Two horizontal incision lines were made 3 cm above the supraorbital rim and 1 cm below the infraorbital rim. Another 2 vertical incisions were on the medial orbital rim and 2 cm lateral to the lateral orbital rim. Elevated flaps were turned over, and the undersurfaces of the periosteum were exposed. A silk string was passed below the periosteum with a 3-mm bite and wound. A 3-cm loop was made, and this was pulled away using the tensiometer. The breaking strength was measured.The breaking strengths of the periosteum were different according to the location (P = 0.000, analysis of variation). The strongest point was 2 cm above the supraorbital rim at the medial one third of the orbit (14.05 [2.50] N) followed by 1 cm above the frontozygomatic suture (13.35 [4.70] N). The weakest point was the infraorbital rim at the lateral one third of the orbit (6.93 [3.76] N) followed by the lateral orbital rim at the level of the lateral canthus (7.60 [3.49] N). Breaking strengths of the periosteum of the medial side (11.44 [3.83] N) were significantly greater (P = 0.021, t-test) than the lateral side (9.32 [3.76] N). In the supraorbital area, the breaking strengths of the periosteum of the upper points (12.91 [3.00] N) were significantly greater (P = 0.000, t-test) than the lower points (9.36 [2.76] N).The results of this study can be of use when choosing a fixation point in rejuvenation surgeries. PMID:25569400

Hwang, Kun; Kim, Han Joon; Han, Seung Ho; Kim, Kyung Yong; Park, Jong Ju; Kim, Seong Kee

2015-01-01

159

The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes  

NASA Astrophysics Data System (ADS)

Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=<0.001) as well as for the pairwise comparison between the different filler group values and between the different soaking times as an individual treatment. Overall, longer soaking times resulted in lower mean DTS values. The DTS of the PCNC for filler #1 decreased to 82.4% of the original value after 1 day of soaking, 67.2% after 7 days and 27.2 % after 28 days. For filler #2 decreased to 54.8% of the original value after 1 day of soaking, 62.3% after 7 days and 61.2% after 28 days. For filler #3 decreased to 71.2% of the original value, 67.3% after 7 days and 51.4% after 28 days (Fig 8). Conclusions: Within the limitation of this study it can be concluded that the use of coupling agent will significantly influence the degradation of the material under wet environment. Clinical Implication: Changes within matrix composition and bonding interphase of resin base composites promise improvements of mechanical properties, decreasing the incidence of clinical failure of posterior composite restorations, hence resulting in a more ideal restorative material for use in posterior segment. The results of this investigation showed that the deficiency of hydrostability in dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the silane coupling agent can dramatically reduce the average lifetime of dental composites.

Yepez, Johanna

160

Analysis of Ninety Degree Flexure Tests for Characterization of Composite Transverse Tensile Strength  

NASA Technical Reports Server (NTRS)

Finite element (FE) analysis was performed on 3-point and 4-point bending test configurations of ninety degree oriented glass-epoxy and graphite-epoxy composite beams to identify deviations from beam theory predictions. Both linear and geometric non-linear analyses were performed using the ABAQUS finite element code. The 3-point and 4-point bending specimens were first modeled with two-dimensional elements. Three-dimensional finite element models were then performed for selected 4-point bending configurations to study the stress distribution across the width of the specimens and compare the results to the stresses computed from two-dimensional plane strain and plane stress analyses and the stresses from beam theory. Stresses for all configurations were analyzed at load levels corresponding to the measured transverse tensile strength of the material.

OBrien, T. Kevin; Krueger, Ronald

2001-01-01

161

Tensile and impact properties of TZM and Mo-5% Re*1  

NASA Astrophysics Data System (ADS)

Some aspects of the mechanical behaviour of two molybdenum alloys, one belonging to the precipitation hardened sub-family (TZM) and the other is a solid solution Mo 5% rhenium-bearing alloy, have been investigated. Experimental data (tensile mechanical strength, ductility and impact properties of unirradiated materials) show that a difference in behaviour exists between the precipitation hardened and the solid solution strengthened alloy, but at the same time a serious discrepancy has been found between the present results and previously reported ductile to brittle transition temperature values for Mo alloys.

Filacchioni, G.; Casagrande, E.; De Angelis, U.; De Santis, G.; Ferrara, D.

1994-09-01

162

Tensile Fracture Strength of Brisbane Tuff by Static and Cyclic Loading Tests  

NASA Astrophysics Data System (ADS)

This research presents the results of laboratory experiments during the investigation of tensile strength-strain characteristics of Brisbane tuff disc specimens under static and diametral cyclic loading. Three different cyclic loading methods were used; namely, sinusoidal cyclic loading, type I and II increasing cyclic loading with various amplitude values. The first method applied the stress amplitude-cycle number (s-n) curve approach to the measurement of the indirect tensile strength (ITS) and fracture toughness ( K IC) values of rocks for the first time in the literature. The type I and II methods investigated the effect of increasing cyclic loading on the ITS and K IC of rocks. For Brisbane tuff, the reduction in ITS was found to be 30 % under sinusoidal loading, whereas type I and II increasing cyclic loading caused a maximum reduction in ITS of 36 %. The maximum reduction of the static K IC of 46 % was obtained for the highest amplitude type I cyclic loading tested. For sinusoidal cyclic loading, a maximum reduction of the static K IC of 30 % was obtained. A continuous irreversible accumulation of damage was observed in dynamic cyclic tests conducted at different amplitudes and mean stress levels. Scanning electron microscope images showed that fatigue damage in Brisbane tuff is strongly influenced by the failure of the matrix because of both inter-granular fracturing and trans-granular fracturing. The main characteristic was grain breakage under cyclic loading, which probably starts at points of contact between grains and is accompanied by the production of very small fragments, probably due to frictional sliding within the weak matrix.

Erarslan, N.; Alehossein, H.; Williams, D. J.

2014-07-01

163

Diametral tensile strength and film thickness of an experimental dental luting agent derived from castor oil  

PubMed Central

The need to develop new dental luting agents in order to improve the success of treatments has greatly motivated research. Objective The aim of this study was to evaluate the diametral tensile strength (DTS) and film thickness (FT) of an experimental dental luting agent derived from castor oil (COP) with or without addition of different quantities of filler (calcium carbonate - CaCO3). Material and Methods Eighty specimens were manufactured (DTS N=40; FT N=40) and divided into 4 groups: Pure COP; COP 10%; COP 50% and zinc phosphate (control). The cements were mixed according to the manufacturers' recommendations and submitted to the tests. The DTS test was performed in the MTS 810 testing machine (10 KN, 0.5 mm/min). For FT test, the cements were sandwiched between two glass plates (2 cm2) and a load of 15 kg was applied vertically on the top of the specimen for 10 min. The data were analyzed by means of one-way ANOVA and Tukey's test (?=0.05). Results The values of DTS (MPa) were: Pure COP- 10.94±1.30; COP 10%- 30.06±0.64; COP 50%- 29.87±0.27; zinc phosphate- 4.88±0.96. The values of FT (µm) were: Pure COP- 31.09±3.16; COP 10%- 17.05±4.83; COP 50%- 13.03±4.83; Zinc Phosphate- 20.00±0.12. One-way ANOVA showed statistically significant differences among the groups (DTS - p=1.01E-40; FT - p=2.4E-10). Conclusion The experimental dental luting agent with 50% of filler showed the best diametral tensile strength and film thickness. PMID:22437672

CARMELLO, Juliana Cabrini; FAIS, Laiza Maria Grassi; RIBEIRO, Lígia Nunes de Moraes; CLARO NETO, Salvador; GUAGLIANONI, Dalton Geraldo; PINELLI, Lígia Antunes Pereira

2012-01-01

164

Correlation analysis of the variation of weld seam and tensile strength in laser welding of galvanized steel  

NASA Astrophysics Data System (ADS)

Many advantages of laser welding technology such as high speed and non-contact welding make the use of the technology more attractive in the automotive industry. Many studies have been conducted to search the optimal welding condition experimentally that ensure the joining quality of laser welding that relies both on welding system configuration and welding parameter specification. Both non-destructive and destructive techniques, for example, ultrasonic inspection and tensile test are widely used in practice for estimating the joining quality. Non-destructive techniques are attractive as a rapid quality testing method despite relatively low accuracy. In this paper, we examine the relationship between the variation of weld seam and tensile shear strength in the laser welding of galvanized steel in a lap joint configuration in order to investigate the potential of the variation of weld seam as a joining quality estimator. From the experimental analysis, we identify a trend in between maximum tensile shear strength and the variation of weld seam that clearly supports the fact that laser welded parts having larger variation in the weld seam usually have lower tensile strength. The discovered relationship leads us to conclude that the variation of weld seam can be used as an indirect non-destructive testing method for estimating the tensile strength of the welded parts.

Sinha, Amit Kumar; Kim, Duck Young; Ceglarek, Darek

2013-10-01

165

Optimization of high filler loading on tensile properties of recycled HDPE/PET blends filled with rice husk  

NASA Astrophysics Data System (ADS)

Biocomposites of recycled high density polyethylene / recycled polyethylene terephthalate (rHDPE/rPET) blend incorporated with rice husk flour (RHF) were prepared using a corotating twin screw extruder. Maleic anhydride polyethylene (MAPE) was added as a coupling agent to improve the fibre-matrix interface adhesion. The effect of high filler loadings (50-90 wt%) on morphology and tensile properties of compatibilized rHDPE/rPET blend was investigated. The results of our study shown that composite with 70 wt% exhibited the highest tensile strength and Young's modulus, which are 22 MPa and 1752 MPa, respectively. The elongation at break decreased with increasing percentage of RHF. SEM micrograph confirmed fillers dispersion, morphological interaction and enhanced interfacial bonding between recycled polymer blends and rice husk. It can be concluded that the optimum RHF content is 70 wt% with maximum tensile strength.

Chen, Ruey Shan; Ahmad, Sahrim; Ghani, Mohd Hafizuddin Ab; Salleh, Mohd Nazry

2014-09-01

166

Effect of storage on tensile material properties of bovine liver.  

PubMed

Cadaveric tissue models play an important role in the assessment and optimization of novel restraint systems for reducing abdominal injuries. However, the effect of tissue preservation by means of freezing on the material properties of abdominal tissues remains unknown. The goal of this study was to investigate the influence of frozen storage time on the material responses of the liver parenchyma in tensile loading. Specimens from ten bovine livers were equally divided into three groups: fresh, 30-day frozen storage, and 60-day frozen storage. All preserved specimens were stored at -12°C. Dog-bone specimens from each preservation group were randomly assigned to one of three strain rates (0.01s(-1), 0.1s(-1), and 1.0s(-1)) and tested to failure in tensile loading. The local material response recorded at the tear location and the global material response of the whole specimen of the liver parenchyma specimens were investigated based on the experimental data and optimized analytical material models. The local and global failure strains decreased significantly between fresh specimens and specimens preserved for 30 days (p<0.05), and between fresh specimens and specimens preserved for 60 days (p<0.05) for all three loading rates. Changes on the material model parameters were also observed between fresh and preserved specimens. Preservation by means of frozen storage was found to affect both the material and failure response of bovine liver parenchyma in tensile loading. The stiffness of the tissue increased with increased preservation time and increased strain rate. In summary, significant changes (p<0.05) between the failure strain of previously frozen liver parenchyma samples and fresh samples were demonstrated at both global and local levels in this study. In addition, nonlinear and viscoelastic characteristics of the liver parenchyma were observed in tension for both fresh and preserved samples. PMID:24148876

Lu, Yuan-Chiao; Kemper, Andrew R; Untaroiu, Costin D

2014-01-01

167

The effect of HIPing on the fatigue and tensile strength of a case, porous-coated Co-Cr-Mo alloy.  

PubMed

The process required to sinter porous Co-Cr-Mo alloys results in the formation of substrate porosity through carbide dissolution. Since hot isostatic pressing (HIPing) has been shown to eliminate casting porosity in the Co-Cr-Mo alloy, it is possible that it may be equally effective on pores that are generated from the sintering operation. The effect that HIPing a porous-coated Co-Cr-Mo material has on the fatigue and tensile properties was investigated. Fatigue testing was performed on sintered materials as well as sintered and HIPed materials, both with and without a porous coating. Further, the effect of varying coating thickness on the resulting fatigue strength of sintered and HIPed materials was studied. Light microscopy was performed in order to define the microstructural changes brought about by the various thermal cycles. Scanning electron microscopy was utilized to define the crack initiation process. The fatigue strength of uncoated "as sintered" materials was found to be reduced by 34% relative to the "as cast" condition. The same material that was HIPed revealed a fatigue strength slightly lower than the "as cast" condition. It was found that porous coatings created preferential sites for fatigue crack initiation. However, the presence of the coating did not further reduce the fatigue strength of "as sintered" materials because of the already low strength created by the sintering operation. Materials that were sintered exhibited a lowering in both tensile strength and elongation to failure relative to the "as cast" condition. The HIPing of sintered materials improved both fatigue and tensile properties relative to the "as sintered" condition. PMID:3782180

Georgette, F S; Davidson, J A

1986-10-01

168

Effect of Beverages on the Hardness and Tensile Bond Strength of Temporary Acrylic Soft Liners to Acrylic Resin Denture Base  

PubMed Central

Statement of Problem: Two potential problems commonly identified with a denture base incorporating a resilient liner are failure of the bond between acrylic resin and soft liner material, and loss of resiliency of the soft liner over time. Since patients may drink different beverages, it is important to evaluate their effects on physical properties of soft lining materials. Purpose: The objective of this in vitro study was to evaluate the effect of different beverages on the hardness of two temporary acrylic-based soft lining materials and their bond strength to the denture base resin. Materials and Method: For the hardness test; a total of 80 rectangular specimens (40mm×10mm×3mm) were fabricated from a heat-polymerized polymethylmethacrylate. Two commercially auto-polymerized acrylic resin-based resilient liners; Coe-Soft and Visco-gel were prepared according to the manufacturers’ instructions and applied on the specimens. For the tensile test, 160 cylindrical specimens (30mm×10mm) were prepared. The liners were added between specimens with a thickness of 3 mm. The specimens of both soft liners were divided into 4 groups (n=10) and immersed in distilled water as the control group, Coca-Cola, 8% and 50% ethanol. All groups were stored in separate containers at 37oC for 12 days. All beverages were changed daily. The hardness was determined using a Shore A durometer and tensile bond strength was determined in a ZwickRoell testing machine at a cross-head speed of 5mm/min. The results were analyzed using two-way ANOVA. Results: There was no significant interaction between the soft liners and the drinks for both hardness (p= 0.748) and bond strength (p= 0.902). There were statistically significant differences between all drinks for both hardness (p< 0.001) and bond strength (p< 0.05). Conclusion: Within the limitations of this study, it seems that drinking Coca-Cola and alcoholic beverages would not be potentially causing any problems for the temporary acrylic soft liners. PMID:24724142

Safari, A; Vojdani, M; Mogharrabi, S; Iraji Nasrabadi, N; Derafshi, R

2013-01-01

169

Non-linear Correlation Between Uniaxial Tensile Properties and Shear-Edge Hole Expansion Ratio  

NASA Astrophysics Data System (ADS)

Stretch flanging of steel sheets is an important formability issue for automobile industry. Finite element simulation study confirms that the edge of the hole deforms in a uniaxial tensile manner during the hole expansion process. To understand the effect of various tensile properties on hole expansion ratio, current experimental data and collected data from published work have been used. Yield stress, ultimate tensile stress, coefficient of normal anisotropy, total elongation, and post uniform elongation are closely related to hole expansion ratio. A non-linear relationship between hole expansion ratio and tensile properties (ultimate tensile stress, coefficient of normal anisotropy, and total elongation) is developed in the present investigation.

Paul, Surajit Kumar

2014-10-01

170

Tensile properties of some copper- and zinc-based alloys: Effects of strain rate and test temperature  

Microsoft Academic Search

This study analyzes the effects of test temperature and strain rate on the tensile properties of some copper-and zinc-based\\u000a alloys. The copper-based alloys comprised a leaded-tin and an aluminum bronze, whereas the zinc-based alloys were added with\\u000a various quantities of aluminum. The aluminum bronze attained maximum room-temperature tensile strength, whereas that of the\\u000a leaded-tin bronze was the least. Among the

B. K. Prasad; A. H. Yegneswaran; A. K. Patwardhan

2000-01-01

171

Heat Treatment Effects on the Tensile Properties and Microstructures of a SiC/RBSN Composite in Nitrogen  

NASA Technical Reports Server (NTRS)

The room-temperature tensile properties and constituent microstructures of a unidirectionally reinforced SiC/reaction bonded silicon nitride (RBSN) composite have been investigated after heat treatments at 1400, 1600, or 1800 C in nitrogen for up to 100 hr. The composite consisted of approximately 24 vol% of aligned 140 micron diameter, continuous length, chemically vapor deposited SiC fibers in an approximately 40% porous silicon nitride matrix. The composites heat treated at 1400 C for up to 100 hr showed elastic modulus, first matrix cracking strength, and ultimate tensile strength values similar to those of the as-fabricated composites, but those heat treated for 1 hr beyond this temperature displayed losses in all three properties. Recrystallization of the SiC fibers, reaction between the carbon-rich interface coating on the fibers and the RBSN matrix, and dissociation of the RBSN matrix are the reasons for the loss of mechanical properties.

Bhatt, R. T.

1995-01-01

172

Effect of He on the structure and bonding properties of W: A first-principles computational tensile test  

NASA Astrophysics Data System (ADS)

Using a first-principles computational tensile test (FPCTT), we have investigated the effect of helium (He) on the structure and bonding properties of tungsten (W), which is a promising plasma-facing material in nuclear fusion Tokamak. Density of states results reveal the underlying reason that the substitutional site for He is the most energetically favorable, while the tetrahedral interstitial site is more favorable than the octahedral interstitial one. The FPCTT shows that the ideal tensile strength is 29.1 GPa at the strain of 14% along the [0 0 1] direction for intrinsic W, while it decreases to 28.2 GPa at the same strain when one impurity He atom is introduced. A local bond-breaking region around He forms in the tensile process due to the presence of He, which suggests He will have a large effect on the bonding properties of W.

Liu, Yue-Lin; Zhou, Hong-Bo; Zhang, Ying; Jin, Shuo; Lu, Guang-Hong

2009-09-01

173

Use of Spherical Instrumented Indentation to Evaluate the Tensile Properties of 3D Combined Structures  

NASA Astrophysics Data System (ADS)

In this paper we propose a novel method, spherical indentation, for evaluation of the plastic properties of combined structures. Three-dimensional (3D) printed products, for example gradient metal alloys consisting of different kinds of material, contain interfaces that can act as weak points and threaten the mechanical reliability of products. Combined structures containing an interface between Cu alloy and Ag were prepared for testing. Samples were heat-treated at 100°C and 200°C for 3 h to optimize processing conditions. The indentation tensile properties of the samples were estimated by analyzing multiple loading-unloading curves obtained by use of the representative stress and strain method. A continuous increase in both yield strength and tensile strength was observed for the Cu alloy and the Cu/Ag interface after heat treatment at up to 200°C, because of precipitation hardening. These experimental results show that mechanical characterization of combined structures by spherical indentation is highly useful on the nano and micro scales.

Song, Won-Seok; Kim, Seung-Gyu; Kim, Young-Cheon; Kwon, Dongil

2015-01-01

174

Structural and High-Temperature Tensile Properties of Special Pitch-Coke Graphites  

NASA Technical Reports Server (NTRS)

The room-temperature structural properties and the tensile properties up to 5000 F (275O C) were determined for ten grades of specially prepared petroleum-coke coal-tar-pitch graphites which were graphitized at 5430 F (3000 C). One impregnation with coal-tar pitch increased the bulk density from 1.41 to 1.57 g/cm3 and the maximum strength at 4500 F (2500 C) from 4000 to 5700 psi. None of the processing parameters studied had a marked effect on the closed porosity or the X-ray structure or the per cent graphitization. The coarse-particle filler resulted in the lowest coefficient of thermal expansion and the fine-particle filler in the highest coefficient. A marked improvement in uniformity of tensile strength was observed. A standard-deviation analysis gave a one-sigma value of approximately 150 psi for one of these special grades and values of 340-420 psi for three commercial grades.

Kotlensky, W. V.; Martens, H. E.

1961-01-01

175

The tensile strength of black bear ( Ursus americanus) cortical bone is not compromised with aging despite annual periods of hibernation  

Microsoft Academic Search

Black bears (Ursus americanus) may not develop disuse osteoporosis during long periods of disuse (i.e. hibernation) because they may be able to maintain bone formation. Previously, we found that cortical bone bending strength was not compromised with age in black bears tibias, despite annual periods of disuse. Here we showed that cortical bone tensile strength (166–198MPa) also does not decrease

Kristin B. Harvey; Thomas D. Drummer; Seth W. Donahue

2005-01-01

176

Simulation of the tensile properties of silica aerogels: the effects of cluster structure and primary particle size.  

PubMed

A new two-level model is proposed to investigate the relationship between the mechanical properties and microstructure of silica aerogels. This two-level model consists of the particle-particle interaction model and the cluster structure model. The particle-particle interaction model is proposed to describe interactions between primary particles, in which the polymerization reaction between primary particles is considered. The cluster structure model represents the geometrical structure of silica aerogels, and it is established using a modified diffusion-limited colloid aggregation (DLCA) algorithm. This two-level model is used to investigate the tensile behavior of silica aerogels based on the discrete element method (DEM). The numerical results show that the primary particle size has significant effects on the elastic modulus and tensile strength of silica aerogels. Moreover, the power-law relationships between tensile properties and aerogel density are dependent on the variation of the primary particle radius with density. The present results can explain the difference among different experimental exponents to a certain extent. In comparison with experimental data within a wide density range, this two-level model provides good quantitative estimations of the elastic modulus and tensile strength of silica aerogels after the size effects of the primary particle are considered. This paper provides a fundamental understanding of the relationship between the mechanical properties and microstructure of silica aerogels. The two-level model can be extended to study the mechanical properties of other aerogels and aerogel composites. PMID:25022232

Liu, Qiang; Lu, Zixing; Zhu, Man; Yuan, Zeshuai; Yang, Zhenyu; Hu, Zijun; Li, Junning

2014-09-01

177

Water Saturation Effects on the Brazilian Tensile Strength of Gypsum and Assessment of Cracking Processes Using High-Speed Video  

NASA Astrophysics Data System (ADS)

This study investigates the water weakening effect on the tensile strength, as well as the fracturing behavior, of an artificially molded Hydrocal B-11 gypsum rock. Brazilian disc tests, with the aid of a high-speed video system to monitor and record the cracking processes, are conducted on dry and wet specimens to determine their tensile strengths. The dry specimens are oven-dried, while the wet specimens are prepared by soaking in water for 1, 3, and 10 weeks to achieve different levels of water content. The test results show that the tensile strength drops to nearly half of its dry value after being soaked in water for only 1 week. The tensile strength reduces only slightly further after the specimens have been immersed in water for 3 and 10 weeks. An analysis of the recorded high-speed footage shows that the primary crack initiates at the center as observed from the surface for the majority of the tested specimens. Most importantly, the cracking processes of dry and wet specimens are distinctly different with regard to the speed of crack propagation and the number of cracks developed.

Wong, Louis Ngai Yuen; Jong, Ming Chuan

2014-07-01

178

Influence of magnetic arc oscillation and current pulsing on microstructure and high temperature tensile strength of alloy 718 TIG weldments  

Microsoft Academic Search

The aim of the present work is to study the effect of magnetic arc oscillation and current pulsing on the microstructure and high temperature tensile strength of alloy 718 tungsten inert gas weldments. The magnetic arc oscillation technique resulted in refined Laves phase with lesser interconnectivity. The full benefits of current pulsing in breaking the dendrites could not be realized

K. Sivaprasad; S. Ganesh Sundara Raman; P. Mastanaiah; G. Madhusudhan Reddy

2006-01-01

179

Improving wet and dry strength properties of recycled old corrugated carton (OCC) pulp using various polymers.  

PubMed

In this study, the application of different dosages of low and high molecular weights (MW) of chitosan (Ch), cationic starch (CS) and poly vinyl alcohol (PVA) were systematically investigated using old corrugated carton (OCC) furnishes. Various sequences of above-mentioned polymeric additives were also examined to find out the optimal combination for improving both wet and dry tensile strength. For each treatment, 4 handsheets, each having basis weight of 100 g/m(2), were made. In general, the tensile strength of handsheets was significantly affected by the addition of polymeric agents. The enhancing effect of additives on dry tensile property was much higher than wet condition. The results also showed that the tensile strength of the samples made from OCC furnishes were improved upon the addition of high molecular weight chitosan (ChI) compared to the untreated ones (control). The low MW chitosan did not change the properties of handsheets dramatically. Application of polymeric agents moderately decreased the stretch to rupture, however with increasing dosage the stretch was improved. Sequential addition of used polymers showed that triple application of polymers was beneficial to both dry and wet tensile strength, although the effect was larger for dry. The best results in wet and dry tensile strengths were achieved using sequential of PVA-ChI-CS. Sequential addition of oppositely charged polymers forms a macromolecular layered structure of polyelectrolytes. PMID:23544577

Hamzeh, Yahya; Sabbaghi, Sanaz; Ashori, Alireza; Abdulkhani, Ali; Soltani, Farshid

2013-04-15

180

Effect of Temperature and Deformation Rate on the Tensile Mechanical Properties of Polyimide Films  

NASA Technical Reports Server (NTRS)

In order to study the structure-property relationships of different processed oriented polyimide films, the mechanical properties will be identified by using tensile tester Instron 4505 and structural information such as the 3-dimensional birefringence molecular symmetry axis and 3-dimensional refractive indices will be determined by using wave guide coupling techniques. The monoaxial drawing techniques utilized in this research are very useful for improving the tensile mechanical properties of aromatic polyimide films. In order to obtain high modulus/high strength polyimide films the following two techniques have been employed, cold drawing in which polyimide films are drawn at room temperature at different cross head speeds and hot drawing in which polyimide films are drawn at different temperatures and cross head speeds. In the hot drawing process the polyimide films are drawn at different temperatures until the glass transition temperature (Tg) is reached by using the environmental chamber. All of the mechanical and optical property parameters will be identified for each sample processed by both cold and hot drawing techniques.

Moghazy, Samir F.; McNair, Kevin C.

1996-01-01

181

Influence of post-superplastic forming practices on the tensile properties of aluminum-lithium alloys  

NASA Astrophysics Data System (ADS)

The effect of thermal processing following superplastic forming on the tensile properties of aluminum-lithium alloys is addressed. The starting materials consisted of alloys 8090, 2090, and X2095 (a Weldalite™ 049 variant) in the form of commercial- grade superplastic sheet. Experience dictates that post- forming practices aimed at a slightly underaged T6 temper produce balanced engineering proper-ties in these alloys. The objective of this study was to assess the potential to use a T5- type temper by elimi-nating the solution heat treatment and/or cold water quenching steps characteristic of T6 processing. The experimental procedures adopted ensured that the tensile properties compiled were representative of the bulk material Initially, the strengthening behavior of each alloy as a function of temper selection was established. Subsequently, aging practices that resulted in peak strength and balanced properties were identified for the baseline T6 temper and two T5 tempers. The implications for replacing a T6 tem-per with a T5- type temper, including rapid and slow cooling following forming, are discussed on the basis of the results.

Hales, S. J.; Lippard, H. E.

1994-06-01

182

Influence of high pressure hydrogen environment on tensile and fatigue properties of stainless steels at low temperatures  

NASA Astrophysics Data System (ADS)

Hydrogen environment embrittlement (HEE) of stainless steels in the environment of high pressure and low temperature hydrogen gas was evaluated using a very simple mechanical properties testing procedure. In the method, the high-pressure hydrogen environment is produced just inside the hole in the specimen. In this work, the effects of HEE on fatigue properties for austenitic stainless steels SUS304L and SUS316L were evaluated at 298 and 190 K. The effects of HEE on the tensile properties of higher strength stainless steels, such as strain-hardened 316, SUS630, and other alloys, SUH660 and Alloy 718 were also examined. The less effect of HEE on fatigue properties of SUS316L and tensile properties of strain-hardened 316 were observed compared with SUS304L and other steels at room temperature and 190 K.

Ogata, T.

2012-06-01

183

Research on tensile strength characteristics of bridge deck pavement bonding layers  

NASA Astrophysics Data System (ADS)

As the development of the traffic in the world, the bridge deck pavement is playing a more and more important role in the whole traffic system. Big span bridge has become more and more especially cement concrete bridge, therefore the bridge deck pavement bonding layers are emphasized as an important part of bridge traffic system, which can mitigate travel impact to bridge and magnify stationary or traffic amenity. The quality and durability of deck pavement bonding layer has directly effect on traffic safety, comfort, durability and investment of bridge. It represents the first line of defence against the ingress of water, road de-icing salts and aggressive chemicals. In real project, many early age damage of bridge deck pavement has become serious disease that affecting the function of bridge. During the construction of the bridge deck, many types of asphalt binders were used, such as styrene-butadiene-styrene (SBS) modified asphalt, styrene-butadiene rubber (SBR) modified asphalt, neoprene latex asphalt, etc. In this paper UTM-25 was used to test the tensile strength of different bridge deck pavement bonding layers with the different treatment methods to inter-surface.

Wu, Shaopeng; Han, Jun

2009-12-01

184

Research on tensile strength characteristics of bridge deck pavement bonding layers  

NASA Astrophysics Data System (ADS)

As the development of the traffic in the world, the bridge deck pavement is playing a more and more important role in the whole traffic system. Big span bridge has become more and more especially cement concrete bridge, therefore the bridge deck pavement bonding layers are emphasized as an important part of bridge traffic system, which can mitigate travel impact to bridge and magnify stationary or traffic amenity. The quality and durability of deck pavement bonding layer has directly effect on traffic safety, comfort, durability and investment of bridge. It represents the first line of defence against the ingress of water, road de-icing salts and aggressive chemicals. In real project, many early age damage of bridge deck pavement has become serious disease that affecting the function of bridge. During the construction of the bridge deck, many types of asphalt binders were used, such as styrene-butadiene-styrene (SBS) modified asphalt, styrene-butadiene rubber (SBR) modified asphalt, neoprene latex asphalt, etc. In this paper UTM-25 was used to test the tensile strength of different bridge deck pavement bonding layers with the different treatment methods to inter-surface.

Wu, Shaopeng; Han, Jun

2010-03-01

185

Root diversity in alpine plants: root length, tensile strength and plant age  

NASA Astrophysics Data System (ADS)

A high diversity of plant species and functional groups is hypothesised to increase the diversity of root types and their subsequent effects for soil stability. However, even basic data on root characteristics of alpine plants are very scarce. Therefore, we determined important root characteristics of 13 plant species from different functional groups, i.e. grasses, herbs and shrubs. We excavated the whole root systems of 62 plants from a machine-graded ski slope at 2625 m a.s.l. and analysed the rooting depth, the horizontal root extension, root length and diameter. Single roots of plant species were tested for tensile strength. The age of herbs and shrubs was determined by growth-ring analysis. Root characteristics varied considerably between both plant species and functional groups. The rooting depth of different species ranged from 7.2 ± 0.97 cm to 20.5 ± 2.33 cm, but was significantly larger in the herb Geum reptans (70.8 ± 10.75 cm). The woody species Salix breviserrata reached the highest horizontal root extensions (96.8 ± 25.5 cm). Most plants had their longest roots in fine diameter classes (0.5

Pohl, M.; Stroude, R.; Körner, C.; Buttler, A.; Rixen, C.

2009-04-01

186

Effect of cooling rate on eutectic cell count, grain size, microstructure, and ultimate tensile strength of hypoeutectic cast iron  

NASA Astrophysics Data System (ADS)

This article describes a series of microstructural and strength studies performed on hypoeutectic cast iron, which was sand cast using a variety of end chills (metallic, nonmetallic, water-cooled, and subzero, respectively). The effects of cooling rate on the eutectic cell count (ECC), grain size, and the ultimate tensile strength (UTS) were evaluated. Attempts were also made to explain these effects and to correlate the UTS with ECC. It was found that subzero chilled and water-cool, chilled cast iron exhibit severe undercooling compared to normal sand cast iron. It was concluded from this investigation that nucleation conditions are completely altered but growth conditions prevail as usual. Therefore, undercooling during solidification is considered to be responsible for variation in ECC, grain size, microstructure, and tensile strength.

Hemanth, J.; Rao, K. V. S.

1999-08-01

187

Effect of Ultrasonic Treatment on The Tensile and Impact Properties of Thermoplastic Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

This study investigates the effect of ultrasonic treatment on the mechanical properties of thermoplastic natural rubber (TPNR) nanocomposites reinforced with multi-walled nanotubes. The TPNR nanocomposites were prepared using melt blending method from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer, respectively, with 1% of Multi-wall nanotubes. The nanocomposite was prepared using the indirect technique (IDT) with the optimum processing parameters at 180° C with 80 rpm mixing speed and 11 minutes processing time. The results have showed that the good dispersion on nanotubes was achieved by ultrasonic treatment. The optimization of ultrasonic time indicated that the maximum tensile and impact properties occurred with 1 h ultrasonic treatment. The Young's modulus, tensile strength, elongation at break and impact strength have increased by almost 11%, 21%, 43% and 50%, respectively. The results from our study indicate that nanotubes have as excellent reinforcement filler in TPNR matrix.

Tarawneh, Mou'ad A.; Ahmad, Sahrim Hj.; Yahya, S. Y.; Rasid, Rozaidi

2009-06-01

188

Effect of irradiation on the fracture behavior and tensile properties of an HT9 duct  

SciTech Connect

Alloy HT9 is a leading candidate material for Liquid Metal Reactor applications because of insignificant swelling and low thermal expansion. To evaluate applications for this alloy, the ACO-1 experiment was conducted. The HT9 alloy was used for cladding and duct for the FFTF Test Assembly. A part of the postirradiation portion of the experiment was the mechanical property testing of the irradiated duct. Results of tensile and fracture toughness tests in samples cut from the HT9 duct are presented in this report. Tensile tests were performed on smooth as well as notched tensile specimens, and fracture toughness tests were performed on compact tension specimens. The postirradiation strength in the lower region of the duct was found to be about 50% stronger than that in the center region. The total elongation for smooth tensile specimens remained at 10% or above for the irradiated specimens taken from the duct various axial locations along the ACO-1 duct. Results showed that irradiation temperature had a strong effect on notched sample behavior. The samples which were irradiated at 360{degree}C and tested at 33{degree}C failed without plastic deformation, their fracture toughness values were also found to be significantly lower than tests at 205{degree}C. This shows that reactor ducts of HT9 irradiated at an FFTF inlet temperature of 360{degree}C have adequate fracture toughness for in-reactor service at temperatures near 200{degree}C, but caution must be taken for duct handling at hot cell temperatures to prevent brittle fracture. 8 refs., 17 figs., 2 tabs.

Huang, F.H.

1989-05-01

189

Effect of particle size and volume fraction on tensile properties of fly ash/polyurea composites  

E-print Network

Effect of particle size and volume fraction on tensile properties of fly ash/polyurea composites polyurea and the polyurea matrix for the composites based on Isonate® 2143L (diisocyanate) and Versalink® P of the composites. Particle size and volume fraction were varied to study their effects on the tensile properties

Nemat-Nasser, Sia

190

The effect of disk type and cutting speed on the micro-tensile bond strength of ceramic specimens to resin cement.  

PubMed

The bond strength of dental materials has been evaluated by tensile testing of micro-specimens. The cutting process used to obtain specimens may influence the results. The objective of this study was to investigate the influence of different types of diamond disks and cutting speeds on the bond strength of ceramic specimens and on specimen integrity. Lithium disilicate-based ceramic cubes were bonded with resin cement to composite resin cubes, according to the manufacturers' instructions. The ceramic/cement/resin blocks thus obtained were divided into two groups to be cut with Buehler(®) or Extec(®) disks and then sectioned at cutting speeds of 200 rpm and 400 rpm. The results showed that the bond strength values were affected by the cutting speed and disk/speed interaction (p<0.05). SEM analysis revealed better specimen properties when the blocks were cut at 200 rpm. It was concluded that ceramic specimens must be cut at low speeds. PMID:25311334

Castro, Martha C C; Sadek, Fernanda T; Batitucci, Eduardo; Miranda, Mauro S

2014-12-01

191

Self-assembled smooth muscle cell tissue rings exhibit greater tensile strength than cell-seeded fibrin or collagen gel rings  

PubMed Central

In this study, we created self-assembled smooth muscle cell (SMC) tissue rings (comprised entirely of cells and cell-derived matrix; CDM) and compared their structure and material properties with tissue rings created from SMC-seeded fibrin or collagen gels. All tissue rings were cultured statically for 7 days in supplemented growth medium (with ?-amino caproic acid, ascorbic acid, and insulin-transferrin-selenium), prior to uniaxial tensile testing and histology. Self-assembled CDM rings exhibited ultimate tensile strength and stiffness values that were two-fold higher than fibrin gel and collagen gel rings. Tensile testing of CDM, fibrin gel and collagen gel rings treated with deionized water to lyse cells showed little to no change in mechanical properties relative to untreated ring samples, indicating that the ECM dominates the measured ring mechanics. In addition, CDM rings cultured in supplemented growth medium were significantly stronger than CDM rings cultured in standard, unsupplemented growth medium. These results illustrate the potential utility of self-assembled cell rings as model CDM constructs for tissue engineering and biomechanical analysis of ECM material properties. PMID:22865465

Adebayo, Olufunmilayo; Gwyther, Tracy A.; Hu, Jason Z.; Billiar, Kristen L.; Rolle, Marsha W.

2012-01-01

192

Structural basis of the tensile strength of protein complexes mediating cell adhesion  

NASA Astrophysics Data System (ADS)

This study explores the behaviour of adhesive complexes of cell adhesion molecules undergoing forced detachment. Molecular-forces measurements combined with Steered Molecular Dynamic (SMD) simulations were used to investigate the mechanical response of the CD2 C58 and hemophilic C-cadherin bonds. The CD2-CD58 adhesive complex, important for the adaptive immune response, contains several salt-bridges in the adhesive interface. SMD simulations showed that these inter-protein salt bridges contribute independently to the tensile strength of the complex. Consistent with this, force measurements with the Surface Force Apparatus (SFA) demonstrated that the elimination of single salt bridges weakens the bond. The corresponding loss in adhesion energy of the CD2-CD58 complex correlates with the importance of the salt bridges observed in the simulations. These findings correlate closely with the effect of the elimination of single salt bridges observed in cell aggregation assays and binding measurements. On the other hand, the hemophilic C-cadherin interaction determines specific cell-cell adhesion during development in Xenopus laevis . Single molecule force spectroscopy was used to characterize the multiple bound states between C-cadherin ectodomains. The experiments showed two short-lived bound states associated with the two outermost ectodomains and two long-lived states associated with the full ectodomain. It is likely that the two short-lived states are involved in the specificity of the interaction since previous studies showed that the corresponding states in E-cadherin have different lifetimes. In addition, SMD simulations of the forced dissociation of the strand dieter of C-cadherin suggested a mechanism for the specificity of cadherin interactions.

Bayas, Marco Vinicio

193

Influence of dilute silicon addition on the oxidation resistance and tensile properties of modified Zircaloy-4  

NASA Astrophysics Data System (ADS)

Si-added modified Zircaloy-4 (Zry-4) and Zr-Si binary alloys were developed to evaluate the effect of silicon addition on zirconium based alloys for high burn-up application. The silicon content varied from 0 to 0.1 wt% for both the alloys. The relationships between alloy chemistry, microstructure, mechanical property and oxidation behavior were investigated. The ultimate tensile strength of the modified Zry-4 generally increased with the increase in silicon content. The optimum silicon content for improved oxidation resistance turned out to be 0.01 wt% from the weight gain measurement. The weight gain decreased with decreasing Si content from 0.1 to 0.01 wt% although the Si free specimen showed higher weight gain than the 0.01 wt% Si specimen. The details of microstuctural change with silicon addition and its influence on tensile properties and oxidation resistance are discussed; the effects of silicon on the oxide crystal structure, second phase precipitates and microstructure of the metal matrix are studied.

Hong, Hyun Seon; Kim, Seon Jin; Lee, Kyung Sub

2002-07-01

194

Effect of Postweld Heat Treatment on Microstructure, Hardness, and Tensile Properties of Laser-Welded Ti-6Al-4V  

NASA Astrophysics Data System (ADS)

The effects of postweld heat treatment (PWHT) on 3.2-mm- and 5.1-mm-thick Ti-6Al-4V butt joints welded using a continuous wave (CW) 4-kW Nd:YAG laser welding machine were investigated in terms of microstructural transformations, welding defects, and hardness, as well as global and local tensile properties. Two postweld heat treatments, i.e., stress-relief annealing (SRA) and solution heat treatment followed by aging (STA), were performed and the weld qualities were compared with the as-welded condition. A digital image correlation technique was used to determine the global tensile behavior for the transverse welding samples. The local tensile properties including yield strength and maximum strain were determined, for the first time, for the laser-welded Ti-6Al-4V. The mechanical properties, including hardness and the global and local tensile properties, were correlated to the microstructure and defects in the as-welded, SRA, and STA conditions.

Kabir, Abu Syed H.; Cao, Xinjin; Gholipour, Javad; Wanjara, Priti; Cuddy, Jonathan; Birur, Anand; Medraj, Mamoun

2012-11-01

195

Evaluation of tensile properties of 5052 type aluminum-magnesium alloy at warm temperatures  

Microsoft Academic Search

Purpose: The purpose of the paper is to evaluate the tensile properties of 5052 type aluminum-manganese alloy in warm temperatures. Design\\/methodology\\/approach: In this research, uniaxial tensile deformation behavior of 5052-H32 type aluminum magnesium alloy was studied range between room to 300°C and in the strain rate range of 0.0083-0.16 s-1. Findings: It was observed that the uniaxial tensile elongation of

F. Ozturk; S. Toros; S. Kilic

196

Tensile and mixed-mode strength of a thin film-substrate interface under laser induced pulse loading  

Microsoft Academic Search

Laser induced stress waves are used to characterize intrinsic interfacial strength of thin films under both tensile and mixed-mode conditions. A short-duration compressive pulse induced by pulsed-laser ablation of a sacrificial layer on one side of a substrate is allowed to impinge upon a thin test film on the opposite surface. Laser-interferometric measurements of test film displacement enable calculation of

Junlan Wang; Nancy R. Sottos; Richard L. Weaver

2004-01-01

197

Evaluation of tensile strength and surface topography of orthodontic wires after infection control procedures: An in vitro study  

PubMed Central

Aim: The aim of this study is to evaluate, the influence of four types of sterilization/disinfection procedures (autoclave, hot air oven, glutaraldehyde, and ultraviolet [UV] light) on the tensile strength and surface topography of three orthodontic wires (stainless steel (SS), titanium - molybdenum alloy [TMA], and cobalt chromium (CoCr)). Materials and Methods: Sample comprised of three types of 8 inches straight length segments of orthodontic wires. They were divided into three groups according to wire composition comprising of 50 samples each. Totally 50 samples of each group were then equally divided into five subgroups according to sterilization method. After sterilization and disinfection of the experimental group, surface topography was examined with scanning electron microscope (SEM) and tensile strength was tested using universal testing machine. Result: The results of this study show that the mean ultimate tensile strength (UTS) of SS wire after four sterilization procedures were similar to the control group (1845.815 ± 142.29 MPa). The mean UTS of TMA wire increases after four sterilization procedures when compared with the control group (874.107 ± 275.939 MPa). The mean UTS of CoCr wire remains same after UV light disinfection, but increases after other three sterilization procedures when compared with the control group (1449.759 ± 156.586 MPa). SEM photographs of the present study shows gross increase in pitting roughness of the surface topography of all the three types of wires after four types of sterilization. Conclusion: Orthodontists who want to offer maximum safety for their patients can sterilize orthodontic wires before placement, as it does not deteriorate the tensile strength and surface roughness of the alloys. PMID:25210383

Brindha, M.; Kumaran, N. Kurunji; Rajasigamani, K.

2014-01-01

198

Tensile bond strength of sealants following Er:YAG laser etching compared to acid etching in permanent teeth.  

PubMed

The aim of this in vitro study was to assess the effect of Er:YAG laser surface treatment on the tensile bond strength of a sealant in permanent teeth. A total of 30 sound third molars were selected and embedded in cold-cure acrylic resin. The enamel surfaces were flattened by a grinding. The teeth were randomly divided into three groups and pretreated as follows: (1) 37% phosphoric acid; (2) Er:YAG laser (1.5 ml/min water spray, 100 mJ energy output, 10 Hz frequency, focal distance 17 mm); (3) Er:YAG laser + 37% phosphoric acid. The treated surfaces were isolated by double adhesive Sellotape and after insertion of a split Teflon matrix at an isolated site, sealant was applied. The specimens were thermocycled and stored at 37°C in distilled water for 72 h, then subjected to a tensile bond strength test (50 kgf at 0.5 mm/min). The mean tensile bond strengths (± SD, in megapascals) were: 18.51 ± 5.68 in group 1, 8.06 ± 2.69 in group 2, and 17.33 ± 5.04 in group 3. Data were submitted to analysis of variance and the Tukey test. No significant difference were found between groups 1 (37% phosphoric acid) and group 3 (Er:YAG laser + 37% phosphoric acid) but treatment with the Er:YAG laser alone (group 2) resulted in significantly lower tensile bond strength than seen in the other groups. In this setting, the Er:YAG laser prepared the enamel surface for sealing but did not eliminate the need for acid etching before sealant application. PMID:21336680

Shahabi, Sima; Bagheri, Hossein G; Ramazani, Kosar

2012-03-01

199

Compression molding and tensile properties of thermoplastic potato starch materials.  

PubMed

The mechanical and melt flow properties of two thermoplastic potato starch materials with different amylose contents were evaluated. The materials were prepared by mixing starch, glycerol, and water, mainly in the weight proportions of 10:3:4.5. Compression molding was used to produce sheets/films with a thickness in the range of 0.3-1 mm. After conditioning at 53% relative humidity (RH) and 23 C, the glycerol-plasticized sheets with a higher amylose content (HAP) were stronger and stiffer than the normal thermoplastic starch (NPS) with an amylose content typical for common potato starch. The tensile modulus at 53% RH was about 160 MPa for the high-amylose material and about 120 MPa for the plasticized NPS. The strain at break was about 50% for both materials. The stress at break was substantially higher for the HAP materials than for the NPS materials, 9.8 and 4.7 MPa, respectively. Capillary viscometry at 140 C showed that the high-amylose material had a higher melt viscosity and was more shear-thinning than the NPS. Dynamic mechanical measurements indicated a broad transition temperature range for both types of starch material. The main transition peaks for glycerol-plasticized starch were located at about room temperature with the transition for the HAP material being at a somewhat higher temperature than that of the NPS material with a lower amylose content. It was also noted that the processing conditions used during the compression molding markedly affected the mechanical properties of the starch material. PMID:16529440

Thunwall, Mats; Boldizar, Antal; Rigdahl, Mikael

2006-03-01

200

Effects of enzymes and gamma irradiation on the tensile strength and morphology of poly(p-dioxanone) fibers  

SciTech Connect

The objective of this study was to examine how and to what extent a new degradable polymeric fiber, poly(p-dioxanone), used as a surgical suture material, degrades in the presence of enzymes and after ..gamma..-irradiation. The degradation of the fiber was studied mechanically using an Instron and morphologically by SEM. Both esterase and trypsine enzymes and their corresponding buffer controls were used. The fibers were ..gamma..-irradiated at the dosages ranging from 0 to 20 Mrad, immersed in the solution for up to 70 days, and then removed for tensile strength and morphological examinations. ..gamma..-irradiation alone lowered the tensile strength of PDS fibers and made them more susceptible to hydrolysis. Esterase and trypsin did not accelerate the hydrolytic degradation of this fiber to any significant level. Both ..gamma..-irradiation and enzymes influenced the gross morphological characteristic of PDS fibers when they were subjected to hydrolysis. The most important morphological observations were the formation of surface cracks and chips on the fibers and the subsequent peeling of the chips. Enzyme-treated PDS fibers exhibited similar morphological findings but the size of the chips was smaller. The morphological observations of PDS fibers were consistent with the tensile strength data. 24 references, 7 figures.

Williams, D.F.; Chu, C.C.; Dwyer, J.

1984-05-01

201

Acoustic emission monitoring of tensile testing of corroded and un-corroded clad aluminum 2024-T3 and characterization of effects of corrosion on AE source events and material tensile properties  

NASA Astrophysics Data System (ADS)

Corrosion damage affects structural integrity and deteriorates material properties of aluminum alloys in aircraft structures. Acoustic Emission (AE) is an effective nondestructive evaluation (NDE) technique for monitoring such damages and predicting failure in large structures of an aircraft. For successful interpretation of data from AE monitoring, sources of AE and factors affecting it need to be identified. This paper presents results of AE monitoring of tensile testing of corroded and un-corroded clad Aluminum 2024-T3 test specimens, and characterization of the effects of strain-rate and corrosion damage on material tensile properties and AE source events. Effect of corrosion was studied by inducing corrosion in the test specimens by accelerated corrosion testing in a Q-Fog accelerated corrosion chamber for 12 weeks. Eight (8) masked dog-bone shaped specimens were placed in the accelerated corrosion chamber at the beginning of the test. Two (2) dog-bone shaped specimens were removed from the corrosion chamber after exposure time of 3, 6, 9, and 12 weeks respectively, and subjected to tension testing till specimen failure along with AE monitoring, as well as two (2) reference samples not exposed to corrosion. Material tensile properties (yield strength, ultimate tensile strength, toughness, and elongation) obtained from tension test and AE parameters obtained from AE monitoring were analyzed and characterized. AE parameters increase with increase in exposure period of the specimens in the corrosive environment. Aluminum 2024-T3 is an acoustically silent material during tensile deformation without any damage. Acoustic emission events increase with increase of corrosion damage and with increase in strain rate above a certain value. Thus AE is suitable for structural health monitoring of corrosion damage. Ultimate tensile strength, toughness and elongation values decrease with increase of exposure period in corrosion chamber.

Okafor, A. Chukwujekwu; Natarajan, Shridhar

2014-02-01

202

Determination of mechanical strength properties of hemp fibers using near-infrared fourier transform Raman microspectroscopy.  

PubMed

Fourier transform near-infrared (FT-NIR) Raman microspectroscopy was adopted for analyzing the micro mechanical tensile deformation behavior of cellulosic plant fibers. Mechanical strength parameters such as tensile strength, failure strain, and Young's modulus of diversified hemp fibers were determined within the range of single fiber cells and fiber filaments. The analysis of fiber deformation at the molecular level was followed by the response of a characteristic Raman signal of fiber cellulose that is sensitive to the tensile load applied. The frequency shift of the Raman signal at 1095 cm(-1) to lower wavenumbers was observed when the fibers were subjected to tensile strain. Microstructural investigations using electron microscopy under environmental conditions supported the discussion of mechanical properties of hemp fibers in relation to several fiber variabilities. Generally, mechanical strength properties of diversified hemp fibers were discussed at the molecular, microstructural, and macroscale level. It was observed that mechanical strength properties of the fibers can be controlled in a broad range by appropriate mercerization parameters such as alkali concentration, fiber shrinkage, and tensile stress applied to the fibers during the alkaline treatments. PMID:16808870

Peetla, Padmaja; Schenzel, Karla C; Diepenbrock, Wulf

2006-06-01

203

Statistical properties of microcracking in polyurethane foams under tensile test, influence of temperature and density  

E-print Network

1 Statistical properties of microcracking in polyurethane foams under tensile test, influence; Power-law scaling Abstract We report tensile failure experiments on polyurethane (PU) foams. Experiments. Specifically, we have used polyurethane foams recognized as ductile at room temperature. We record acoustic

Boyer, Edmond

204

Short-term mechanical properties of high-strength light-weight concrete  

NASA Astrophysics Data System (ADS)

An experimental investigation was undertaken to establish the mechanical properties of high-strength light-weight concrete. Concretes having compressive strengths ranging from 2,564 to 8,585 psi, and densities between 90 and 103 pcf were tested. The results include a comprehensive study of the engineering properties of light-weight concrete. Data are presented on compressive strength gain with age, speciment size effect, static modulus of elasticity, Poisson's ratio, modulus of rupture, splitting tensile strength, and drying effects. Results are compared to data on normal-weight concrete. The deformation characteristics of light-weight concrete are studied in detail.

Morales, S. M.

1982-08-01

205

Effect of boron on tensile properties of B2 BeAl  

NASA Technical Reports Server (NTRS)

Small additions of boron were shown to improve the room temperature ductility of the intermetallic compound Ni3Al. Boron is believed to segregate to the gain boundaries and strengthen them, allowing the inheret ductility of the grains to be achieved. The present study was undertaken to see if boron has a similar effect on the low temperature tensile properties of the equiatomic intermetallic compound FeAl. A binary alloy without boron is compared with an alloy containing 0.78 at % B (0.2 wt %) B, by tensile testing over the temperature range of 300 K to 640 K. Both alloys were processed by powder metallurgy. Results showed that 0.78 at % B addition to FeAl does indeed change the room temperature fracture mode from intergranular to transgranular, suggesting a strengthening of grain boundaries. The alloy containing boron is, however, still brittle at room temperature. A slight decrease in the ductile to brittle transition temperature is, nevertheless, observed. In addition a significant increase in strength of the alloy is observed with boron addition.

Crimp, M.; Vedula, K.

1986-01-01

206

Root tensile strength of grey alder and mountain maple grown on a coarse grained eco-engineered slope in the Swiss Alps related to wood anatomical features  

NASA Astrophysics Data System (ADS)

Steep, vegetation free slopes are a common feature in alpine areas. The material covering these slopes is prone to all kind of erosional processes, resulting in a high risk potential for population and infrastructure. This risk potential is likely to increase with the predicted change in the spatiotemporal distribution of precipitation events. A potential increase in extreme precipitation events will also result in a higher magnitude and frequency of erosional processes. In the Swiss Alps as in many other mountainous areas, there is a need to stabilize these slopes to reduce their direct or indirect hazard potential. In this regard, eco-engineering is a very promising and sustainable approach for slope stabilization. Planting trees and shrubs is a central task in eco-engineering. A developing vegetation cover will on one hand reduce the mechanical effects of rainfall by an increased interception, on the other hand, the root systems cause modifications of soil properties. Roots not only provide anchorage for the plants, they also promote soil aggregation and are able to penetrate possible shear horizons. Overall, anchorage of plants is at the same extend also stabilizing the near subsurface. When rainfall occurs, the saturated soil exerts downhill pressure to a tree or shrub. As long as the root distribution supports anchorage, the respective slope area remains stable. At this point, the tensile strength of the roots is a critical measure, because it is more likely that the supporting roots break than the entire root system being pulled out of the soil completely. As a consequence, root tensile strength is an important parameter in characterizing the soil stabilization potential of trees and shrubs. It is known that tree roots show a high variability in their anatomical structure depending on their depth below soil surface as well as their distance to the main stem. Therefore, we assume that these structural changes affect the tensile strength of every single root. In order to confirm this assumption and possibly find more important root properties which have an influence on soil stabilization, the root systems of seven trees (three grey alder, four mountain maple) were excavated and analyzed. The study site is a catchment, where shallow landslides are common. It is located in the Prättigau valley in the Eastern Swiss Alps and was eco-engineered in 1997. The substrate is coarse-grained morainic material, mean annual air temperature reaches 4.64°C, average precipitation is 1170 mm, and the altitude is about 1000 m a.s.l.. The root system of each tree was uncovered carefully by hand to keep the roots undamaged, before removal it was photographed in situ to document the root distribution. The root systems were then cut into single root pieces of about 20 cm length and the position of each sample was documented. The root samples were then hierarchically classified in several root classes. The tensile strength of more than 500 samples was determined. In addition, the values for age, diameter, and root moisture were ascertained. Since it was assumed, that the cellular structure of the roots has an influence on the tensile strength, two microscopic thin-sections were prepared from all successfully tested root samples. The microscopic analysis focused on anatomical parameters such as the size and number of vessels, their distribution as well as their conductivity. The results for the final correlation between the anatomical characteristics and the root's tensile strength are presented for both tree species.

Kink, Dimitri; Bast, Alexander; Meyer, Christine; Meier, Wolfgang; Egli, Markus; Gärtner, Holger

2014-05-01

207

The tensile strength of 339 aluminum reinforced with Kaowool fibers: A comparison of T5 and T6 heat treatments  

SciTech Connect

This study compares the effects of T5 and T6 heat treatment on the tensile strengths of both KAOWOOL fiber reinforced and unreinforced 339 aluminum. The 339 Al-T6 is stronger than 339 AL-T5 (as expected), but for a KAOWOOL/339 Al composite, the T5 condition is substantially stronger than the T6. The controlling parameter is the strength of the aluminum dendrites, which in turn is proportional to the concentration of magnesium retained in the dendrites. In the T5 condition, more than half of the magnesium is in the form of large intermetallics in both the unreinforced alloy and the KAOWOOL/339 Al composite. During a T6 heat treatment, magnesium in the intermetallics is redissolved. In the unreinforced T6 alloy, this additional magnesium is retained in and strengthens the dendrites. But in the T6 composite, the magnesium segregates extensively to the KAOWOOL/aluminum interfaces depleting and softening the dendrites. This factor along is sufficient to account for the low strength of the T6 composites. The tensile strengths of both the T5 and T6 composites correspond to the calculated values for a perfectly bonded system.

Baxter, W.J.; Sachdev, A.K. [General Motors R and D Center, Warren, MI (United States). Metallurgy Dept.

1999-07-01

208

Effects of polymerization and briquetting parameters on the tensile strength of briquettes formed from coal coke and aniline-formaldehyde resin  

SciTech Connect

In this work, the utilization of aniline (C{sub 6}H{sub 7}N) formaldehyde (HCHO) resins as a binding agent of coke briquetting was investigated. Aniline (AN) formaldehyde (F) resins are a family of thermoplastics synthesized by condensing AN and F in an acid solution exhibiting high dielectric strength. The tensile strength sharply increases as the ratio of F to AN from 0.5 to 1.6, and it reaches the highest values between 1.6 and 2.2 F/AN ratio; it then slightly decreases. The highest tensile strength of F-AN resin-coke briquette (23.66 MN/m{sup 2}) was obtained from the run with 1.5 of F/AN ratio by using (NH4){sub 2}S{sub 2}O{sub 8} catalyst at 310 K briquetting temperature. The tensile strength of F-AN resin-coke briquette slightly decreased with increasing the catalyst percent to 0.10%, and then it sharply decreased to zero with increasing the catalyst percent to 0.2%. The effect of pH on the tensile strength is irregular. As the pH of the mixture increases from 9.0 to 9.2, the tensile strength shows a sharp increase, and the curve reaches a plateau value between pH 9.3 and 9.9; then the tensile strength shows a slight increase after pH = 9.9.

Demirbas, A.; Simsek, T. [Selcuk University, Konya (Turkey)

2006-10-15

209

Influence of different brazing and welding methods on tensile strength and microhardness of orthodontic stainless steel wire.  

PubMed

The aim of this study was to compare the mechanical strength and microhardness of joints made by conventional brazing and tungsten inert gas (TIG) and laser welding. A standardized end-to-end joint configuration of the orthodontic wire material in spring hard quality was used. The joints were made using five different methods: brazing (soldering > 450 degrees C) with universal silver solder, two TIG, and two laser welders. Laser parameters and welding conditions were used according to the manufacturers' guidance. The tensile strengths were measured with a universal testing machine (Zwick 005). The microhardness measurements were carried out with a hardness tester (Zwick 3202). Data were analysed using one-way analysis of variance and Bonferroni's post hoc correction (P < 0.05). In all cases, brazing joints ruptured at low levels of tensile strength (198 +/- 146 MPa). Significant differences (P < 0.001) between brazing and TIG or laser welding were found. The highest means were observed for TIG welding (699-754 MPa). Laser welding showed a significantly lower mean tensile strength (369-520 MPa) compared with TIG welding. Significant differences (P < 0.001) were found between the original orthodontic wire and the mean microhardness at the centre of the welded area. The mean microhardness differed significantly between brazing (1.99 GPa), TIG (2.22-2.39 GPa) and laser welding (2.21-2.68 GPa). For orthodontic purposes, laser and TIG welding are solder-free alternatives to joining metal. TIG welding with a lower investment cost is comparable with laser welding. However, while expensive, the laser technique is a sophisticated and simple method. PMID:18617503

Bock, Jens Johannes; Fraenzel, Wolfgang; Bailly, Jacqueline; Gernhardt, Christian Ralf; Fuhrmann, Robert Andreas Werner

2008-08-01

210

Ultrasonic Elastic Properties of Steel under Tensile Stress  

Microsoft Academic Search

Longitudinal and transverse wave velocities, eight kinds of elastic parameters and dilational and shear dampings of chromium-molybdenum steel have been simultaneously measured at room temperature in terms of acoustoelasticity, by an ultrasonic pulse method. Young, shear and bulk moduli and Lamé parameter apparently decrease with increasing tensile stress, suggesting decrement of rigidity. However, decease in Poisson's ratio shows actual enhancement

Mikio Fukuhara; Asao Sampei

2000-01-01

211

Influence of powder/liquid ratio on the radiodensity and diametral tensile strength of glass ionomer cements  

PubMed Central

Objective To determine the influence of P/L ratio on the radiodensity and diametral tensile strength (DTS) of glass ionomer cements. Material and Methods There were 2 factors under study: P/L ratio (manufacturer's recommended P/L ratio and a 50% reduced P/L ratio), and materials (Vitro Molar, Vitro Fil, Vitro Cem conventional GICs and Vitro Fil LC, Ortho Glass LC RMGICs). Five 1-mm-thick samples of each material-P/L ratio were produced for radiodensity evaluation. Samples were x-ray exposed onto Digora phosphor plate and radiodensity was obtained using the software Digora for Windows 2.5 Rev 0. For DTS, five (4.0x8.0 mm) cylinder samples of each material were tested (0.5 mm/min). Data were subjected to one- and two-way ANOVA (5x2) followed by Tukey's HSD test, or Kruskal-Wallis and Dunn's method. For paired comparisons, t-test or Mann-Whitney test were used (a=0.05). Results There was a significant interaction (P=0.001) for the studied factors (materials vs. P/L ratio). Reduced P/L ratio resulted in significantly lower DTS for the RMGICs, but radiodensity was affected for all materials (P<0.05). Conclusions Reduced P/L ratio affected properties of the tested glass ionomer cements. RMGICs were more susceptible to lower values of DTS, but radiodensity decreased for all materials following P/L ratio reduction. PMID:21308288

FONSECA, Rodrigo Borges; BRANCO, Carolina Assaf; QUAGLIATTO, Paulo Sérgio; GONÇALVES, Luciano de Souza; SOARES, Carlos José; CARLO, Hugo Lemes; CORRER-SOBRINHO, Lourenço

2010-01-01

212

Experimental investigation of the tensile properties and failure mechanisms of three-dimensional woven composites.  

E-print Network

??This PhD thesis presents an experimental investigation into the tensile properties, strengthening mechanics and failure mechanisms of three-dimensional (3D) woven composites with through-the-thickness (z-binder) reinforcement.… (more)

Rudov-Clark, S

2007-01-01

213

Space environmental effects on graphite-epoxy compressive properties and epoxy tensile properties  

NASA Technical Reports Server (NTRS)

This study characterizes the effects of electron radiation and temperature on a graphite-epoxy composite material. Compressive properties of the T300/934 material system were obtained at -250 F (-157 C), room temperature, and 250 F (121 C). Tensile specimens of the Fiberite 934 epoxy resin were fabricated and tested at room temperature and 250 F (121 C). Testing was conducted in the baseline (nonirradiated) and irradiated conditions. The radiation exposure was designed to simulate 30 year, worst-case exposure in geosynchronous Earth orbit. Mechanical properties tended to degrade at elevated temperature and improve at cryogenic temperature. Irradiation generally degraded properties at all temperatures.

Fox, Derek J.; Sykes, George F., Jr.; Herakovich, Carl T.

1987-01-01

214

Nondestructive determination of tensile properties and fracture toughness of cold worked A36 steel  

Microsoft Academic Search

Tensile and fracture properties of ASTM grade A36 steel have been studied using nondestructive Stress–Strain Microprobe™ system (SSM), which is developed on the basis of automated ball indentation (ABI) technique. Tests have been carried out on as-received, and cold worked (4, 8 and 12%) materials at several temperatures in the range ?150°C–+200°C at a constant strain rate. Tensile properties determined

K. L. Murty; M. D. Mathew; Y. Wang; V. N. Shah; F. M. Haggag

1998-01-01

215

The Value Compressive Strength and Split Tensile Strength on Concrete Mixture With Expanded Polystyrene Coated by Surfactant Span 80 as a Partial Substitution of Fine Aggregate  

NASA Astrophysics Data System (ADS)

The value of the density normal concrete which ranges between 2200-2400 kg/m3. Therefore the use of Expanded Polystyrene (EPS) as a subitute to fine aggregate can reduce the density of concrete. The purpose this research is to reduce the density of normal concrete but increase compressive strength of EPS concrete, with use surfactant as coating for the EPS. Variables of substitution percentage of EPS and EPS coated by surfactant are 5%,10%,15%,20%,25%. Method of concrete mix design based on SNI 03-2834-2000 "Tata Cara Pembuatan Rencana Campuran Beton Normal (Provisions for Proportioning Normal Concrete Mixture)". The result of testing, every increase percentage of EPS substitution will decrease the compressive strength around 1,74 MPa and decrease density 34,03 kg/m3. Using Surfactant as coating of EPS , compressive strength increase from the EPS's compressive strength. Average of increasing compressive strength 0,19 MPa and increase the density 20,03 kg/m3,average decrease of the tensile split strength EPS coated surfaktan is 0,84 MPa.

Hidayat, Irpan; Siauwantara, Alice

2014-03-01

216

Studies of Microtexture and Its Effect on Tensile and High-Cycle Fatigue Properties of Laser-Powder-Deposited INCONEL 718  

NASA Astrophysics Data System (ADS)

The current work studies the microstructure, texture, and mechanical properties of INCONEL 718 alloy (IN718) produced by laser direct metal deposition. The grain microstructure exhibits an alternative distribution of banded fine and coarse grain zones as a result of the rastering scanning pattern. The effects of the anisotropic crystallographic texture on the tensile and high-cycle fatigue (HCF) properties at room temperature are investigated. Tensile test results showed that the tensile strength of laser-deposited IN718 after direct aging or solution heat treatment is equivalent to the minimum-forged IN718 properties. The transverse direction (relative to the laser scanning direction) produces >10 pct stiffer modulus of elasticity but 3 to 6 pct less tensile strength compared to the longitudinal direction due to the preferential alignment of grains having <111> and <100> directions parallel to the tensile loading direction. Laser-deposited IN718 with good metallurgical integrity showed equivalent HCF properties compared to the direct-aged wrought IN718, which can be attributed to the banded grain size variation and cyclic change of inclining grain orientations resulted from alternating rastering deposition path.

Qi, Huan; Azer, Magdi; Deal, Andrew

2012-11-01

217

Effect of oxidation on tensile properties of a V-5Cr-5Ti alloy  

SciTech Connect

Oxidation studies were conducted on V-5Cr-5Ti alloy specimens at 5000{degrees}C in an air environment to evaluate the alloy`s oxygen uptake behavior as a function of temperature and exposure time. Oxidation rates, calculated from measurements of thermogravimetric testing, are 5, 17, and 27 {mu}m after a 1-yr exposure at 300, 400, and 5000{degrees}C, respectively. Uniaxial tensile tests were conducted on preoxidized specimens of the alloy to examine the effects of oxidation and oxygen migration on tensile strength and ductility. Microstructural characteristics of several of the tested specimens were characterized by electron-optical techniques. Correlations have been developed between the tensile strength and ductility of the oxidized alloy and microstructural characteristics such as oxide thickness, depth of hardened layer, depth of intergranular fracture zone, and transverse crack length.

Natesan, K.; Soppet, W.K.

1995-05-01

218

Effect of oxygen and oxidation on tensile properties of V-5Cr-5Ti alloy  

SciTech Connect

Oxidation studies were conducted on V-5Cr-5Ti alloy specimens in an air environment to evaluate the oxygen uptake behavior of the alloy as a function of temperature and exposure time. The oxidation rates calculated from parabolic kinetic measurements of thermogravimetric testing and confirmed by microscopic analyses of cross sections of exposed specimens were 5, 17, and 27 {mu}m per year after exposure at 300, 400, and 500{degrees}C, respectively. Uniaxial-tensile tests were conducted at room temperature and at 500C on preoxidized specimens of the alloy to examine the effects of oxidation and oxygen migration on tensile strength and ductility. Microstructural characteristics of several of the tested specimens were determined by electron optics techniques. Correlations were developed between tensile strength and ductility of the oxidized alloy and microstructural characteristics such as oxide thickness, depth of hardened layer, depth of intergranular fracture zone, and transverse crack length.

Natesan, K.; Soppet, W.K.

1995-09-01

219

Development of a new method to determine dynamic tensile strength of ballistic yarns  

NASA Astrophysics Data System (ADS)

Since the design of new soft protections is getting intensive, the study of the dynamic behavior of ballistic yarns becomes more and more important. This paper deals with the development of a new experimental method in order to obtain some dynamic parameters by performing dynamic tensile tests. The concept is quite simple: two projectiles, linked together by the ballistic yarn we want to study, are accelerated together with the help of a gas gun. The first one flies freely while the second one is suddenly stopped. The yarn is then loaded in tensile. Several measurements are performed during each test with the help of a high speed camera. First results on a polyethylene yarn are presented here and several improvements are proposed in order to improve the accuracy of the results.

Nussbaum, J.; Faderl, N.; Nuesing, R.; Ha-Minh, C.; Boussu, F.

2012-08-01

220

Tensile and fatigue properties of two titanium alloys as candidate materials for fusion reactors  

NASA Astrophysics Data System (ADS)

Titanium alloys have been identified as candidate structural materials for the first wall, the blanket and the magnetic coil structures of fusion reactors. Titanium alloys are interesting materials because of their high specific strength and low elastic modulus, their low swelling tendency and their fast induced radioactivity decay. Other attractive properties are an excellent resistance to corrosion and good weldability, even in thick sections. Furthermore titanium alloys are suitable for components exposed to heat loads since they have a low thermal stress parameter. Titanium alloys with an ? structure are believed to have a good resistance against radiation embrittlement and ?+? alloys should possess the best tolerance to hydrogen embrittlement. Two classical industrially available alloys in the two families, the Ti5Al2.4Sn and the Ti6Al4V alloys have been used in this study. The tensile properties between room temperature and 450°C are reported. A low cycle fatigue analysis has been performed under strain control at total strain ranges between 0.8% and 2% and at a temperature of 350°C. The microstructure of both alloys was investigated before and after both types of deformation. Both alloys exhibit excellent mechanical properties comparable to or better than those of ferritic martensitic steels.

Marmy, P.; Leguey, T.; Belianov, I.; Victoria, M.

2000-12-01

221

Tensile and impact properties of V-4Cr-4Ti alloy heats 832665 and 832864.  

SciTech Connect

Two large heats of V-4Cr-4Ti alloy were produced in the United States in the past few years. The first, 832665, was a 500 kg heat procured by the U.S. Department of Energy for basic fusion structural materials research. The second, 832864, was a 1300 kg heat procured by General Atomics for the DIII-D radiative divertor upgrade. Both heats were produced by Oremet-Wah Chang (previously Teledyne Wah Chang of Albany). Tensile properties up to 800 C and Charpy V-notch impact properties down to liquid nitrogen temperature were measured for both heats. The product forms tested for both heats were rolled sheets annealed at 1000 C for 1 h in vacuum. Testing results show the behavior of the two heats to be similar and the reduction of strengths with temperature to be insignificant up to at least 750 C. Ductility of both materials is good in the test temperature range. Impact properties for both heats are excellent--no brittle failures at temperatures above -150 C. Compared to the data for previous smaller laboratory heats of 15-50 kg, the results show that scale-up of vanadium alloy ingot production to sizes useful for reactor blanket design can be successfully achieved as long as reasonable process control is implemented.

Bray, T. S.; Tsai, H.; Nowicki, L. J.; Billone, M. C.; Smith, D. L.; Johnson, W. R.; Trester, P. W.

1999-11-08

222

Tensile property of a hot work tool steel prepared by biomimetic coupled laser remelting process with different laser input energies  

NASA Astrophysics Data System (ADS)

Coupled with the biomimetic principle, a hot work tool steel (4Cr5MoSiV1) was manufactured using a laser with different input energies. Results of tensile tests confirmed that the biomimetic coupled laser remelting (BCLR) process had an advance effect on improving the strength and ductility of 4Cr5MoSiV1 steel simultaneously. Microstructure examinations demonstrated that a fine microstructure along with nano scale carbide was acquired in the BCLR units, which produced an accumulative contribution of grain refinement, precipitation strengthening and a mixed microstructure. Based on the well distribution of the BCLR units, the beneficial effect of stress transfer from the matrix to the units on tensile property was also analyzed.

Wang, Chuanwei; Zhou, Hong; Zhang, Zhihui; Zhao, Yu; Zhang, Peng; Cong, Dalong; Meng, Chao; Tan, Fuxing

2012-09-01

223

Effects of helium implantation on the tensile properties and microstructure of Ni73P27 metallic glass nanostructures.  

PubMed

We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ?130 nm diameter Ni73P27 metallic glass nanocylinders. The nanocylinders were fabricated by a templated electroplating process and implanted with He(+) at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ?3 atom % throughout the nanocylinders. Transmission electron microscopy imaging and through-focus analysis reveal that the specimens contained ?2 nm helium bubbles distributed uniformly throughout the nanocylinder volume. In situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens with no sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation. PMID:25084487

Liontas, Rachel; Gu, X Wendy; Fu, Engang; Wang, Yongqiang; Li, Nan; Mara, Nathan; Greer, Julia R

2014-09-10

224

Influence of excessive filler coating on the tensile properties of LDPE–calcium carbonate composites  

Microsoft Academic Search

Calcium carbonate fillers are usually coated with stearic acid to reduce their surface energy and improve their dispersion in polymers. Commercial products are often over-coated and contain an excess of surfactant. It was found that stearic acid linearly increases the modulus and yield stress of LDPE but reduces its tensile strength, yield strain, and ultimate elongation. The influence of surfactant

Maged A. Osman; Ayman Atallah; Ulrich W. Suter

2004-01-01

225

Tensile strength of the cement-bone interface depends on the amount of bone interdigitated with PMMA cement  

Microsoft Academic Search

An experimental investigation was performed to (1) determine the general mechanical behavior and in particular, the post-yield behavior of the cement-bone interface under tensile loading, (2) determine where interface failure occurs, and (3) determine if the mechanical properties of the interface could be related to the density of bone at the interface and\\/or the amount of cement-bone interdigitation. Seventy-one cement-bone

K. A. Mann; D. C. Ayers; F. W. Werner; R. J. Nicoletta; M. D. Fortino

1997-01-01

226

Apparatus for measuring tensile and compressive properties of solid materials at cryogenic temperatures  

DOEpatents

An apparatus for evaluating the tensile and compressive properties of material samples at very low or cryogenic temperatures employs a stationary frame and a dewar mounted below the frame. A pair of coaxial cylindrical tubes extend downward towards the bottom of the dewar. A compressive or tensile load is generated hydraulically and is transmitted by the inner tube to the material sample. The material sample is located near the bottom of the dewar in a liquid refrigerant bath. The apparatus employs a displacement measuring device, such as a linear variable differential transformer, to measure the deformation of the material sample relative to the amount of compressive or tensile force applied to the sample.

Gonczy, John D. (Oaklawn, IL); Markley, Finley W. (St. Charles, IL); McCaw, William R. (Burr Ridge, IL); Niemann, Ralph C. (Downers Grove, IL)

1992-01-01

227

Tensile Properties of Poly (N-vinyl caprolactam) Gels  

NASA Technical Reports Server (NTRS)

N-vinyl caprolactam was copolymerized with ethylene glycol dimethacrylate using a free-radical initiator in alcohol/water solution. The resulting gels were thermally-responsive in water, undergoing an approximate fivefold reversible volume shrinkage between room temperature and ca. 50 C. Tensile testing showed that the stress-strain behavior was qualitatively different in the collapsed state above the temperature-induced transition. At the higher temperature, gels were stiffer, more ductile, and showed greater time dependence. Implications for the design of gel actuators are briefly discussed.

Morgret, Leslie D.; Hinkley, Jeffrey A.

2004-01-01

228

Waiting Time for Coronal Preparation and the Influence of Different Cements on Tensile Strength of Metal Posts  

PubMed Central

This study aimed to assess the effect of post-cementation waiting time for core preparation of cemented cast posts and cores had on retention in the root canal, using two different luting materials. Sixty extracted human canines were sectioned 16?mm from the root apex. After cast nickel-chromium metal posts and cores were fabricated and luted with zinc phosphate (ZP) cement or resin cement (RC), the specimens were divided into 3 groups (n = 10) according to the waiting time for core preparation: no preparation (control), 15 minutes, or 1 week after the core cementation. At the appropriate time, the specimens were subjected to a tensile load test (0.5?mm/min) until failure. Two-way ANOVA (time versus cement) and the Tukey tests (P < 0.05) showed significantly higher (P < 0.05) tensile strength values for the ZP cement groups than for the RC groups. Core preparation and post-cementation waiting time for core recontouring did not influence the retention strength. ZP was the best material for intraradicular metal post cementation. PMID:22291705

Oliveira, Ilione Kruschewsky Costa Sousa; Arsati, Ynara Bosco de Oliveira Lima; Basting, Roberta Tarkany; França, Fabiana Mantovani Gomes

2012-01-01

229

Effect of varying chromophores used in light-activated protein solders on tensile strength and thermal damage profile of repairs.  

PubMed

Clinical adoption of laser tissue welding (LTW) techniques has been beleaguered by problems associated with thermal damage of tissue and insufficient strength of the resulting tissue bond. The magnitude of these problems has been significantly reduced with the incorporation of indocyanine green (ICG)-doped protein solders into the LTW procedure to form a new technique known as laser tissue soldering (LTS). With the addition of ICG, a secondary concern has arisen relating to the potential harmful effects of the degradation products of the chromophore upon thermal denaturation of the protein solder with a laser. In this study, two different food colorings were investigated, including blue #1 and green consisting of yellow #5 and blue #1, as alternative chromophores for use in LTS techniques. Food coloring has been found to have a suitable stability and safety profile for enteral use when heated to temperatures above 200 degrees C; thus, it is a promising candidate chromophore for LTS which typically requires temperatures between 50 degrees C and 100 degrees C. Experimental investigations were conducted to test the tensile strength of ex vivo repairs formed using solders doped with these alternative chromophores in a bovine model. Two commonly used chromophores, ICG and methylene blue (MB), were investigated as a reference. In addition, the temperature rise, depth of thermal coagulation in the protein solder, and the extent of thermal damage in the surrounding tissue were measured. Temperature rise at the solder/tissue interface, and consequently the degree of solder coagulation and collateral tissue thermal damage, was directly related to the penetration depth of laser light in the protein solder. Variation of the chromophore concentration such that the laser light penetrated to a depth approximately equal to half the thickness of the solder resulted in uniform results between each group of chromophores investigated. Optimal tensile strength of repairs was achieved by optimizing laser and solder parameters to obtain a temperature of approximately 65 degrees C at the solder/tissue interface. The two alternative chromophores tested in this study show considerable promise for application in LTS techniques, with equivalent tensile strength to solders doped with ICG or MB, and the potential advantage of eliminating the risks associated with harmful byproducts. PMID:12724861

Hoffman, Grant T; Byrd, Brian D; Soller, Eric C; Heintzelman, Douglas L; McNally-Heintzelman, Karen M

2003-01-01

230

Studies on weld metal characteristics and their influence on tensile and fatigue properties of pulsed-current GMA welded Al-Zn-Mg alloy  

SciTech Connect

Pulsed-current GMA welding of an extruded section of Al-Zn-Mg alloy (7005) was carried out by using Al-Mg (5183) welding wire. During welding, the pulse parameters, such as pulse frequency and duration, were varied and their effects on the zinc pickup due to dilution of base material, porosity content and microstructure, as well as the hardness, tensile and fatigue properties of the weld metal were studied. The zinc pickup of the weld was correlated to its hardness and both the zinc pickup and porosity content of the weld were correlated to the tensile strength and fatigue life of the weld. The characteristics and mechanical properties of the pulsed-current GMA weld were compared with those of a continuous-current weld. It was observed that the variation in the pulse parameters affects the zinc pickup, porosity content and microstructure of the weld. The increase in zinc pickup enhanced the hardness, tensile strength and fatigue life, whereas, the porosity content was found to reduce the tensile strength and fatigue life of the weld. The pulsed-current GMA welding was found to improve the weld properties over those of continuous-current GMA welds.

Potluri, N.B. [Auburn Univ., AL (United States). Materials Engineering Program; Ghosh, P.K.; Gupta, P.C.; Reddy, Y.S. [Univ. of Roorkee (India)

1996-02-01

231

Tensile strength at elevated temperature and its applicability as an accelerated testing methodology for unidirectional composites  

NASA Astrophysics Data System (ADS)

The applicability of a macroscopic time-temperature superposition principle (TTSP) to unidirectional composite strength is discussed based on the microscopic Simultaneous Fiber-Failure (SFF) model that has been presented by Koyanagi et al. (J. Compos. Mater. 43:1901-1914, 2009a). The SFF model estimates composite strengths as functions of fiber, matrix, and interface strengths. This paper first investigates the applicability of SFF to the complicated temperature dependence of composite strengths, i.e., one composite exhibits significant temperature dependence and another does not, considering the temperature dependence of the components, which results in successful estimations for the two composite systems used in the present study. The long-term durability predicted by the SFF and that predicted by the TTSP are then compared. They typically correspond to each other in various cases; accelerated testing methodology (ATM) employing TTSP is thus proved to be valid from the micromechanical viewpoint, assuming the SFF applicability.

Koyanagi, Jun; Nakada, Masayuki; Miyano, Yasushi

2012-02-01

232

Relevance of impacter shape to nonvisible damage and residual tensile strength of a thick graphite/epoxy laminate  

NASA Technical Reports Server (NTRS)

A study was made to determine the relevance of impacter shape to nonvisible damage and tensile residual strength of a 36 mm (1.4 in.) thick graphite/epoxy motor case. The shapes of the impacters were as follows: 12.7 mm (0.5 in.) and 25.4 mm (1.0 in.) diameter hemispheres, a sharp corner, and a 6.3 mm (0.25 in.) diameter bolt-like rod. The investigation revealed that damage initiated when the contact pressure exceeded a critical level. However, the damage was not visible on the surface until an even higher pressure was exceeded. The damage on the surface consisted of a crater shaped like the impacter, and the damage below the surface consisted of broken fibers. The impact energy to initiate damage or cause visible damage on the surface increased approximately with impacter diameter to the third power. The reduction in strength for nonvisible damage increased with increasing diameter, 9 and 30 percent for the 12.7 mm (0.5 in.) and 25.4 mm (1.0 in.) diameter hemispheres, respectively. The corner impacter made visible damage on the surface for even the smallest impact energy. The rod impacter acted like a punch and sliced through the composite. Even so, the critical level of pressure to initiate damage was the same for the rod and hemispherical impacters. Factors of safety for nonvisible damage increased with increasing kinetic energy of impact. The effects of impacter shape on impact force, damage size, damage visibility, and residual tensile strength were predicted quite well assuming Hertzian contact and using maximum stress criteria and a surface crack analysis.

Poe, C. C., Jr.

1990-01-01

233

Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin  

PubMed Central

Objective The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM. Material and Methods Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student's t-test. The failure modes of all groups were also evaluated. Results The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure. Conclusion The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces. PMID:21710095

TÜRKMEN, Cafer; DURKAN, Meral; C?M?LL?, Hale; ÖKSÜZ, Mustafa

2011-01-01

234

Tuning electronic and magnetic properties of partially hydrogenated graphene by biaxial tensile strain: a computational study  

PubMed Central

Using density functional theory calculations, we have investigated the effects of biaxial tensile strain on the electronic and magnetic properties of partially hydrogenated graphene (PHG) structures. Our study demonstrates that PHG configuration with hexagon vacancies is more energetically favorable than several other types of PHG configurations. In addition, an appropriate biaxial tensile strain can effectively tune the band gap and magnetism of the hydrogenated graphene. The band gap and magnetism of such configurations can be continuously increased when the magnitude of the biaxial tensile strain is increased. This fact that both the band gap and magnetism of partially hydrogenated graphene can be tuned by applying biaxial tensile strain provides a new pathway for the applications of graphene to electronics and photonics. PMID:25258610

2014-01-01

235

Hierarchical composites of carbon nanotubes on carbon fiber: Influence of growth condition on fiber tensile properties  

Microsoft Academic Search

Growing carbon nanotubes (CNT) on the surface of high performance carbon fibers (CF) provides a means to tailor the thermal, electrical and mechanical properties of the fiber–resin interface of a composite. However, many CNT growth processes require pretreatment of the fiber, deposition of an intermediate layer, or harsh growth conditions which can degrade tensile properties and limit the conduction between

Qiuhong Zhang; Jianwei Liu; Ryan Sager; Liming Dai; Jeffery Baur

2009-01-01

236

Residual strength of composite laminates subjected to tensile-compressive fatigue loading  

NASA Technical Reports Server (NTRS)

Results are presented on the measurements of the residual strengths of T300/934 graphite epoxy laminates, in tension and in compression, after the samples were exposed to tension-compression fatigue loading (R = -1). Four laminate ocnfigurations were tested: unidirectional, cross-ply, angle-ply, and quasi-isotropic. It was found that the fatigue behavior of laminates was dependent on the quasi-static strengths and the specific structure of the laminate. No direct correlation was found between remaining residual strengths and the percentage of average fatigue life. However, a correlation scheme was developed for the individual specimen under test, based on a cumulative damage model and a stiffness change of the material.

Rotem, Assa; Nelson, H. G.

1990-01-01

237

Physical Property Measurements: Unconfined Compressive Strength (UCS)  

NSDL National Science Digital Library

This site, by the Colorado School of Mines, addresses the properties of a measurement technique called unconfined compression strength (UCS). Along with defining the technique, the website shows different experiments, pictures and diagrams associated with UCS. This well organized work will be a valuable asset for any geology or engineering classroom.

Ozdemir, Levent

2008-09-17

238

Evaluation of a sugar based edible adhesive utilizing a tensile strength tester  

Technology Transfer Automated Retrieval System (TEKTRAN)

A new method to evaluate adhesives has been developed and utilized to formulate a recently patented adhesive based on sugar and citric acid. Factors affecting adhesive performance were uncovered, such as reduced strength due to improper heating time, and an optimal curing temperature of 60oC was ac...

239

LEONARDO DA VINCI'S TENSILE STRENGTH TESTS: IMPLICATIONS FOR THE DISCOVERY OF ENGINEERING MECHANICS  

Microsoft Academic Search

In one of Leonardo Da Vinci's notebooks, an experiment is described where strengths in tension are measured for various lengths of wire. The notebook indicates that the results of these experiments were that longer wires were weaker than shorter wires. This result defies classical mechanics of materials. This conflict has been explained as a note-taking failure by Leonardo. This short

JAY R. LUND; JOSEPH P. BYRNE

2001-01-01

240

Microstructure and tensile properties after thermohydrogen processing of Ti-6 Al-4V.  

PubMed

Thermohydrogen processing (THP), a technique in which hydrogen is used as a temporary alloying element, can refine the microstructure and improve the final mechanical properties of the Ti-6 Al-4V alloy. THP allows microstructural modification of titanium alloys near net shape such as biomaterial components obtained by powder metallurgy and castings, since it does not require mechanical working. Two THP, called THP-A and THP-B, have been evaluated in samples of Ti-6Al-4V with a coarse and lamellar microstructure typical of castings and powder metallurgy. The THP-A is based in the eutectoid decomposition of the beta(H) phase to alpha phase and hydride phase. The THP-B is based in the isothermal decomposition of alpha('') martensite phase, obtained by quenching of hydrogenated samples. The refinement of the microstructure due to THP has been evaluated by means of optical and electron microscopy. Tensile tests showed that while both processes were able to increase the strength of the alloy as compared with the starting material, the ductility in samples subjected to THP-B was severely reduced. PMID:19627819

Guitar, A; Vigna, G; Luppo, M I

2009-04-01

241

The variability and interdependence of spider viscid line tensile properties.  

PubMed

True stress-true strain curves of naturally spun viscid line fibres retrieved directly from the spiral of orb-webs built by Argiope trifasciata spiders were measured using a novel methodology. This new procedure combines a method for removing the aqueous coating of the fibres and a technique that allows the accurate measurement of their cross-sectional area. Comparison of the tensile behaviour of different samples indicated that naturally spun viscid lines show a large variability, comparable to that of other silks, such as major ampullate gland silk and silkworm silk. Nevertheless, application of a statistical analysis allowed the identification of two independent parameters that underlie the variability and characterize the observed range of true stress-true strain curves. The combination of this result with previous mechanical and microstructural data suggested the assignment of these two independent effects to the degree of alignment of the protein chains and to the local relative humidity, which, in turn, depends on the composition of the viscous coating and on the external environmental conditions. PMID:24072798

Perea, Gracia Belén; Plaza, Gustavo R; Guinea, Gustavo V; Elices, Manuel; Velasco, Beatriz; Pérez-Rigueiro, José

2013-12-15

242

Tensile testing of SiC whiskers  

SciTech Connect

The room temperature tensile mechanical properties of SiC whiskers have been examined using a micro-tensile-test apparatus. SiC whiskers exhibit an average tensile strength of 8.4 GPa for a 5 mm tested length, and an average elastic modulus of 581 GPa. These results indicate that SiC whiskers possess significant potential as short-fiber reinforcement elements in ceramic matrix composites.

Petrovic, J.J.

1984-01-01

243

Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study  

PubMed Central

Background: The condition of the denture bearing tissues may be adversely affected by high stress concentration during function. Chairside Denture (Hard and Soft) reliners are used to distribute forces applied to soft tissues during function. Tensile and shear bond strength has been shown to be dependent on their chemical composition. A weak bond could harbor bacteria, promote staining and delamination of the lining material. To investigate tensile and shear bond strength of 4 different commercially available denture relining materials to conventional heat cured acrylic denture base resin. Materials & Methods: 4 mm sections in the middle of 160 Acrylic cylindrical specimens (20 mm x 8 mm) were removed, packed with test materials (Mollosil, G C Reline Soft, G C Reline Hard (Kooliner) and Ufi Gel Hard and polymerized. Specimens were divided into 8 groups of 20 each. Tensile and shear bond strength to the conventional heat cured acrylic denture base resin were examined by Instron Universal Tensile Testing Machine using the equation F=N/A (F-maximum force exerted on the specimen (Newton) and A-bonding area= 50.24 mm2). One-way ANOVA was used for multiple group comparisons followed by Bonferroni Test and Hsu’s MCB for multiple pairwise comparisons to asses any significant differences between the groups. Results: The highest mean Tensile bond strength value was obtained for Ufi Gel Hard (6.49+0.08 MPa) and lowest for G C Reline Soft (0.52+0.01 MPa). The highest mean Shear bond strength value was obtained for Ufi Gel Hard (16.19+0.1 MPa) and lowest for Mollosil (0.59+0.05 MPa). The Benferroni test showed a significant difference in the mean tensile bond strength and the mean shear bond strength when the two denture soft liners were compared as well as when the two denture hard liners were compared. Hsu’s MCB implied that Ufi gel hard is better than its other closest competitors. Conclusion: The Tensile and Shear bond strength values of denture soft reliners were significantly lower than denture hard reliners. How to cite the article: Lau M, Amarnath GS, Muddugangadhar BC, Swetha MU, Das KA. Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study. J Int Oral Health 2014;6(2):55-61. PMID:24876703

Lau, Mayank; Amarnath, G S; Muddugangadhar, B C; Swetha, M U; Das, Kopal Anshuraj Ashok Kumar

2014-01-01

244

Elastic properties, strength and damage tolerance of pultruded composites  

NASA Astrophysics Data System (ADS)

Pultruded composites are candidate materials for civil engineering infrastructural applications due their higher corrosion resistance and lower life cycle cost. Efficient use of materials like structural members requires thorough understanding of the mechanism that affects their response. The present investigation addresses the modeling and characterization of E-glass fiber/polyester resin matrix pultruded composites in the form of sheets of various thicknesses. The elastic constants were measured using static, vibration and ultrasonic methods. Two types of piezoelectric crystals were used in ultrasonic measurements. Finally, the feasibility of using a single specimen, in the form of a circular disk, was shown in measuring all the elastic constants using ultrasonic technique. The effects of stress gradient on tensile strength were investigated. A large number of specimens, parallel and transverse to the pultrusion direction, were tested in tension, 3-point flexure, and 4-point flexure. A 2-parameter Weibull model was applied to predict the tensile strength from the flexure tests. The measured and Weibull-predicted ratios did not show consistent agreement. Microstructural observations suggested that the flaw distribution in the material was not uniform, which appears to be a basic requirement for the Weibull distribution. Compressive properties were measured using a short-block compression test specimen of 44.4-mm long and 25.4-mm wide. Specimens were tested at 0°, 30°, 45°, 60° and 90° orientations. The compression test specimen was modeled using 4-noded isoparametric layered plate and shell elements. The predicted elastic properties for the roving layer and the continuous strand mat layer was used for the finite element study. The damage resistance and damage tolerance were investigated experimentally. Using a quasi-static indentation loading, damage was induced at various incrementally increased force levels to investigate the damage growth process. Damage parameters were measured in the form of dent depth, back surface crack length, and damage area. The compression tests were performed, using an end-gripped compression test fixture, on both the damaged specimens and open-hole specimens. A relationship between the compressive strength and hole-diameter was established. The compressive strength of damaged specimens was compared to determine the "equivalent-hole-diameter." A correlation between damage parameters and the "equivalent-hole-diameter" was established to find a parameter that could be used as a measure of damage resistance and damage tolerance of pultruded composite structures.

Saha, Mrinal Chandra

245

Effect of different surface preparations on the tensile strength of adhesively bonded metal joints  

Microsoft Academic Search

In this in vitro study, the effects of different surface preparations and resins on the strength and durability of adhesively bonded joints were evaluated. Disk-shaped cobalt-chromium substrate samples of the first group were treated by the Silicoater MD® system. Samples of the two subgroups were bonded with two different bisphenol-A glycidyl methacrylate (Bis-GMA) adhesives. Samples of the second group were

Mahmoud Abd El Salam Shakal; Peter Pfeiffer

1998-01-01

246

Effect of Load Rate on Ultimate Tensile Strength of Ceramic Matrix Composites at Elevated Temperatures  

NASA Technical Reports Server (NTRS)

The strengths of three continuous fiber-reinforced ceramic composites, including SiC/CAS-II, SiC/MAS-5 and SiC/SiC, were determined as a function of test rate in air at 1100 to 1200 C. All three composite materials exhibited a strong dependency of strength on test rate, similar to the behavior observed in many advanced monolithic ceramics at elevated temperatures. The application of the preloading technique as well as the prediction of life from one loading configuration (constant stress-rate) to another (constant stress loading) suggested that the overall macroscopic failure mechanism of the composites would be the one governed by a power-law type of damage evolution/accumulation, analogous to slow crack growth commonly observed in advanced monolithic ceramics. It was further found that constant stress-rate testing could be used as an alternative to life prediction test methodology even for composite materials, at least for short range of lifetimes and when ultimate strength is used as the failure criterion.

Choi, Sung R.; Gyekenyesi, John P.

2001-01-01

247

The elevated temperature tensile properties of S-200E commercially pure beryllium  

SciTech Connect

Experiments were performed at 300-100 C in longitudinal and transverse orientations at quasi-static strain rate 5.5 {times} 10{sup {minus}4}s{sup {minus}1}. Results show that the stress-strain curve is smooth, without yield points or serrations. Yield stress and ultimate tensile stress decrease monotonically with temperature. Similar strengths were measured for both orientations. Failure elongation vs temperature is complex.

Henshall, G.A.; Torres, S.G.; Hanafee, J.E.

1995-03-01

248

Determination of biofilm mechanical properties from tensile tests performed using a micro-cantilever method  

Microsoft Academic Search

Recently, a micro-cantilever method was introduced for measuring the ultimate tensile strength of intact bacterial biofilms. Herein, is reported the analysis of the video files from the testing of a 4-day-old Staphylococcus epidermidis biofilm to determine the elastic modulus, toughness, and failure strain. Elastic modulus (1270±280 Pa) was within the range of previously reported values (17–6000 Pa). The high failure

Srijan Aggarwal; Raymond M. Hozalski

2010-01-01

249

Creep and tensile properties of several oxide-dispersion-strengthened nickel-base alloys at 1365 K  

NASA Technical Reports Server (NTRS)

The tensile properties at room temperature and at 1365 K and the tensile creep properties at low strain rates at 1365 K were measured for several oxide-dispersion-strengthened (ODS) alloys. The alloys examined included ODS Ni, ODS Ni-20Cr, and ODS Ni-16Cr-Al. Metallography of creep tested, large grain size ODS alloys indicated that creep of these alloys is an inhomogeneous process. All alloys appear to possess a threshold stress for creep. This threshold stress is believed to be associated with diffusional creep in the large grain size ODS alloys and normal dislocation motion in perfect single crystal (without transverse low angle boundaries) ODS alloys. Threshold stresses for large grain size ODS Ni-20Cr and Ni-16Cr-Al type alloys are dependent on the grain aspect ratio. Because of the deleterious effect of prior creep on room temperature mechanical properties of large grain size ODS alloys, it is speculated that the threshold stress may be the design limiting creep strength property.

Wittenberger, J. D.

1977-01-01

250

The Tensile Properties of Advanced Nickel-Base Disk Superalloys During Quenching Heat Treatments  

NASA Technical Reports Server (NTRS)

There is a need to increase the temperature capabilities of superalloy turbine disks. This would allow full utilization of higher temperature combustor and airfoil concepts under development. One approach to meet this goal is to modify the processing and chemistry of advanced alloys, while preserving the ability to use rapid cooling supersolvus heat treatments to achieve coarse grain, fine gamma prime microstructures. An important step in this effort is to understand the key high temperature tensile properties of advanced alloys as they exist during supersolvus heat treatments. This could help in projecting cracking tendencies of disks during quenches from supersolvus heat treatments. The objective of this study was to examine the tensile properties of two advanced disk superalloys during simulated quenching heat treatments. Specimens were cooled from the solution heat treatment temperatures at controlled rates, interrupted, and immediately tensile tested at various temperatures. The responses and failure modes were compared and related to the quench cracking tendencies of disk forgings.

Gabb, Timothy P.; Gayda, John; Kantzos, Pete T.; Biles, Tiffany; Konkel, William

2001-01-01

251

Tensile Properties and Integrity of Clean Room and Low-Modulus Disposable Nitrile Gloves: A Comparison of Two Dissimilar Glove Types  

PubMed Central

Background: The selection of disposable nitrile exam gloves is complicated by (i) the availability of several types or formulations, (ii) product variability, and (iii) an inability of common quality control tests to detect small holes in the fingers. Differences in polymer formulation (e.g. filler and plasticizer/oil content) and tensile properties are expected to account for much of the observed variability in performance. Objectives: This study evaluated the tensile properties and integrity (leak failure rates) of two glove choices assumed to contain different amounts of plasticizers/oils. The primary aims were to determine if the tensile properties and integrity differed and if associations existed among these factors. Additional physical and chemical properties were evaluated. Methods: Six clean room and five low-modulus products were evaluated using the American Society for Testing and Materials Method D412 and a modified water-leak test to detect holes capable of passing a virus or chemical agent. Results: Significant differences in the leak failure rates and tensile properties existed between the two glove types (P ? 0.05). The clean room gloves were about three times more likely to have leak failures (chi-square; P = 0.001). No correlation was observed between leak failures and tensile properties. Solvent extract, an indication of added plasticizer/oil, was not associated with leak failures. However, gloves with a maximum modulus <4 MPa or area density (AD) <11 g cm?2 were about four times less likely to leak. Conclusions: On average, the low-modulus gloves were a better choice for protection against aqueous chemical or biological penetration. The observed variability between glove products indicated that glove selection cannot rely solely on glove type or manufacturer labeling. Measures of modulus and AD may aid in the selection process, in contrast with common measures of tensile strength and elongation at break. PMID:22201179

Phalen, Robert N.; Wong, Weng kee

2012-01-01

252

Tensile Properties and Microstructure of Inconel 718 Fabricated with Electron Beam Freeform Fabrication (EBF(sup 3))  

NASA Technical Reports Server (NTRS)

Electron beam freeform fabrication (EBF3) direct metal deposition processing was used to fabricate two Inconel 718 single-bead-width wall builds and one multiple-bead-width block build. Specimens were machined to evaluate microstructure and room temperature tensile properties. The tensile strength and yield strength of the as-deposited material from the wall and block builds were greater than those for conventional Inconel 718 castings but were less than those for conventional cold-rolled sheet. Ductility levels for the EBF3 material were similar to those for conventionally-processed sheet and castings. An unexpected result was that the modulus of the EBF3-deposited Inconel 718 was significantly lower than that of the conventional material. This low modulus may be associated with a preferred crystallographic orientation resultant from the deposition and rapid solidification process. A heat treatment with a high solution treatment temperature resulted in a recrystallized microstructure and an increased modulus. However, the modulus was not increased to the level that is expected for Inconel 718.

Bird, R. Keith; Hibberd, Joshua

2009-01-01

253

Hardness distribution and tensile properties in an electron beam weldment of F82H irradiated in HFIR  

NASA Astrophysics Data System (ADS)

F82H-IEA and its EB-weld joint were irradiated at 573 and 773 K up to 9.6 dpa and the irradiation effect on its mechanical properties and microstructure were investigated. A hardness profile across the weld joint before irradiation showed the hardness in transformed region (TR) was high and especially that in the edge of TR was the highest (high hardness region: HHR) compared to base metal (BM). These hardness distribution was correspond to grain size distribution. After irradiation, hardening in HHR was small compared to other region in the sample. In tensile test, the amount of hardening in yield strength and ultimate tensile strength of F82H EB-weld joint was almost similar to that of F82H-IEA but the fracture position of EB-weld joint was at the boundary of TR and BM. Therefore, the TR/BM boundary is the structural weak point in F82H EB-weld joint after irradiation. As the plastic instability was observed, the dislocation channeling deformation can be expected though the dislocation channel was not observed in this study.

Oka, H.; Hashimoto, N.; Muroga, T.; Kimura, A.; Sokolov, M. A.; Yamamoto, T.; Ohnuki, S.

2014-12-01

254

Temperature dependence of the tensile properties of single-walled carbon nanotubes: O(N) tight-binding molecular-dynamics simulations  

NASA Astrophysics Data System (ADS)

This paper examines the effect of temperature on the structural stability and mechanical properties of 20-layered (10,10) single-walled carbon nanotubes (SWCNTs) under tensile loading using an O(N) tight-binding molecular-dynamics simulation method. We observed that (10,10) tube can sustain its structural stability for the strain values of 0.23 in elongation and 0.06 in compression at 300K . Bond-breaking strain value decreases with increasing temperature under stretching but not under compression. The elastic limit, Young’s modulus, tensile strength, and Poisson ratio are calculated as 0.10, 0.395TPa , 83.23GPa , and 0.285, respectively, at 300K . In the temperature range from 300to900K , Young’s modulus and the tensile strengths decrease with increasing temperature while the Poisson ratio increases. At higher temperatures, Young’s modulus starts to increase while the Poisson ratio and tensile strength decrease. In the temperature range from 1200to1800K , the SWCNT is already deformed and softened. Applying strain on these deformed and softened SWCNTs does not follow the same pattern as in the temperature range of 300to900K .

Dereli, Gülay; Süngü, Banu

2007-05-01

255

Improved tensile creep properties of yttrium-and lanthanum-doped alumina: a solid solution effect  

E-print Network

Improved tensile creep properties of yttrium- and lanthanum-doped alumina: a solid solution effect- and lanthanum-doped alumina (at dopant levels below the solubility limit) was examined. Both compositions (100 ppm yttrium, 100 ppm lanthanum) exhibited a uniform microstructure consisting of fine, equiaxed grains

Cho, Junghyun

256

Tensile and thermal properties of nanocellulose-reinforced poly(vinyl alcohol) nanocomposites  

Microsoft Academic Search

This work reports on the mechanical and thermal properties of poly(vinyl alcohol) (PVA) nanocomposites reinforced with nanocelluloses isolated by the sulfuric acid hydrolysis using commercial microcrystalline cellulose (MCC). Nanocellulose-reinforced PVA nanocomposite films were prepared by the casting method with different nanocellulose loadings, which were exposed to tensile test, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The nanocellulose obtained by

Mi-Jung Cho; Byung-Dae Park

2011-01-01

257

Vol. 79, No. 2, 2002 261 Tensile Properties of Extruded Corn Protein  

E-print Network

Vol. 79, No. 2, 2002 261 Tensile Properties of Extruded Corn Protein Low-Density Polyethylene Films products, petroleum conservation, and con- servation of landfill space. Research in protein films has focused on the production of solvent- cast films. Corn and wheat protein (Aydt et al 1991; Herald et al

258

Optical measurements of vocal fold tensile properties: Implications for phonatory mechanics  

Microsoft Academic Search

In voice research, in vitro tensile stretch experiments of vocal fold tissues are commonly employed to determine the tissue biomechanical properties. In the standard stretch-release protocol, tissue deformation is computed from displacements applied to sutures inserted through the thyroid and arytenoid cartilages, with the cartilages assumed to be rigid. Here, a non-contact optical method was employed to determine the actual

Jordan E. Kelleher; Thomas Siegmund; Roger W. Chan; Erin A. Henslee

2011-01-01

259

Tensile properties of short-glass-fiber- and short-carbon-fiber-reinforced polypropylene composites  

Microsoft Academic Search

Composites of polypropylene (PP) reinforced with short glass fibers (SGF) and short carbon fibers (SCF) were prepared with extrusion compounding and injection molding techniques. The tensile properties of these composites were investigated. It was noted that an increase in fiber volume fraction led to a decrease in mean fiber length as observed previously. The relationship between mean fiber length and

S.-Y Fu; B Lauke; E Mäder; C.-Y Yue; X Hu

2000-01-01

260

Sub-Microsecond Yield and Tensile Strengths of Metals and Alloys at Elevated Temperatures  

NASA Astrophysics Data System (ADS)

The shock-wave tests have been carried out for Armco-iron, aluminum and Al-6%Mg alloy, and titanium of different purity at temperatures up to 600°C. The dynamic yield stresses are practically athermal for Al-6%Mg alloy and titanium of commercial purity, decrease for Armco-iron and anomalously increase for titanium of high purity with increasing the temperature. The different behaviors of metals and alloys are treated in terms of relationship between phonon drag of motion of dislocations and the drag forces created by obstacles. The spall strength slightly decreases with increasing the temperature and, for polycrystalline aluminum and aluminum alloy, precipitously drops as temperature approaches the melting point. The waveforms for pure titanium indicate irreversible polymorphic transformations at normal and elevated temperatures.

Razorenov, S. V.; Savinykh, A. S.; Kanel, G. I.; Skakun, S. N.

2004-07-01

261

Ultimate tensile strength of embedded I-sections: a comparison of experimental and numerical results  

NASA Astrophysics Data System (ADS)

Exposed baseplates together with anchor bolts are the customary method of connection of steel structures to the concrete footings. Post-Kobe studies revealed that the embedded column bases respond better to the earthquake uplift forces. The embedded column bases also, offer higher freedom in achieving the required strength, rigidity and ductility. The paper presents the results of the pullout failure of three embedded IPE140 sections, tested under different conditions. The numerical models are then, generated in Abaqus 6.10-1 software. It is concluded that, the steel profiles could be directly anchored in concrete without using anchor bolts as practiced in the exposed conventional column bases. Such embedded column bases can develop the required resistance against pullout forces at lower constructional costs.

Heristchian, Mahmoud; Pourakbar, Pouyan; Imeni, Saeed; Ramezani, M. Reza Adib

2014-12-01

262

Effect of the Position of Immobilization Upon the Tensile Properties in Injured Achilles Tendon of Rat  

PubMed Central

Objective To examine the effect of the posture of immobilization upon the tensile properties in injured Achilles tendon of rat for an initial period of immobilization. Methods Forty-two Sprague-Dawley rats were used in the present study. Eighteen rats received a total tenotomy of the right Achilles tendon to mimic total rupture and were divided into three groups comprising of 6 rats each. Ankles of group A were immobilized at 60° of plantarflexion. Ankles of group B were immobilized at neutral position. Whereas, those of group C were immobilized at 60° of dorsiflexion. Other 18 rats received hemitenotomy to mimic partial rupture and were divided into three groups. The remaining 6 rats were kept free as control. After 14 days, we dissected the tendons and analyzed maximum force, stiffness, and energy uptake during pulling of the tendons until they ruptured. The tendons of 6 rats in each group and control were reserved for histology. Picrosirius staining was done for the analysis of collagen organization. Results In total tenotomy, tensile properties were significantly different between the control and the intervention groups (p<0.05). Group C showed relatively higher values than the groups A and B with respect to tensile properties (p>0.05). In partial tenotomy, tensile properties were significantly different between the control and the intervention groups (p<0.05). Group C showed significantly higher value than other intervention groups in terms of maximum force and energy uptake (p<0.05). The semiquantitative histologic grading scores were assigned for collagen organization. The scores for dorsiflexion posture were higher than the ones for plantarflexion. Conclusion Dorsiflexion posture in partial ruptured Achilles tendon showed better functional recovery than other immobilized postures. In total ruptured case, the tensile properties showed increasing tendency in dorsiflexion posture. PMID:23525566

Min, Yong; Kwon, Young-Bae; Lee, Min-Ho

2013-01-01

263

Improved tensile strength of glycerol-plasticized gluten bioplastic containing hydrophobic liquids  

Microsoft Academic Search

The aim of the present work has been to study the influence of hydrophobic liquids on the morphology and the properties of thermo-molded plastics based on glycerol-plasticized wheat gluten (WG). While the total amount of castor oil and glycerol was remained constant at 30wt%, castor oil with various proportions with respect to glycerol was incorporated with WG by mixing at

Yihu Song; Qiang Zheng

2008-01-01

264

Dependence of ultimate tensile strength of friction stir welded AA2024-T6 aluminium alloy on friction stir welding process parameters  

Microsoft Academic Search

parameters. The present research work is aimed to evaluate the interaction effects of four process parameters viz., tool rotational speed N, welding speed S, tool pin diameter D and tool axial plunging force F on the tensile strength of FS welded AA2024 -T6 joints fabricated using the newly developed tool. Response surface method (RSM) was em- ployed to develop the

N. Shanmuga Sundaram; N. Murugan

265

Report on thermal aging effects on tensile properties of ferritic-martensitic steels.  

SciTech Connect

This report provides an update on the evaluation of thermal-aging induced degradation of tensile properties of advanced ferritic-martensitic steels. The report is the first deliverable (level 3) in FY11 (M3A11AN04030103), under the Work Package A-11AN040301, 'Advanced Alloy Testing' performed by Argonne National Laboratory, as part of Advanced Structural Materials Program for the Advanced Reactor Concepts. This work package supports the advanced structural materials development by providing tensile data on aged alloys and a mechanistic model, validated by experiments, with a predictive capability on long-term performance. The scope of work is to evaluate the effect of thermal aging on the tensile properties of advanced alloys such as ferritic-martensitic steels, mod.9Cr-1Mo, NF616, and advanced austenitic stainless steel, HT-UPS. The aging experiments have been conducted over a temperature of 550-750 C for various time periods to simulate the microstructural changes in the alloys as a function of time at temperature. In addition, a mechanistic model based on thermodynamics and kinetics has been used to address the changes in microstructure of the alloys as a function of time and temperature, which is developed in the companion work package at ANL. The focus of this project is advanced alloy testing and understanding the effects of long-term thermal aging on the tensile properties. Advanced materials examined in this project include ferritic-martensitic steels mod.9Cr-1Mo and NF616, and austenitic steel, HT-UPS. The report summarizes the tensile testing results of thermally-aged mod.9Cr-1Mo, NF616 H1 and NF616 H2 ferritic-martensitic steels. NF616 H1 and NF616 H2 experienced different thermal-mechanical treatments before thermal aging experiments. NF616 H1 was normalized and tempered, and NF616 H2 was normalized and tempered and cold-rolled. By examining these two heats, we evaluated the effects of thermal-mechanical treatments on material microstructures and associated mechanical properties during long-term aging at elevated temperatures. Thermal aging experiments at different temperatures and periods of time have been completed: 550 C for up to 5000 h, 600 C for up to 7500 h, and 650 C for more than 10,000 h. Tensile properties were measured on thermally aged specimens and aging effect on tensile behavior was assessed. Effects of thermal aging on deformation and failure mechanisms were investigated by using in-situ straining technique with simultaneous synchrotron XRD measurements.

Li, M.; Soppet, W.K.; Rink, D.L.; Listwan, J.T.; Natesan, K. (Nuclear Engineering Division)

2012-05-10

266

Effect of neutron irradiation on microstructure and tensile properties of TZM and Mo-5% Re alloys  

NASA Astrophysics Data System (ADS)

The response of two molybdenum alloys (e.g. TZM and Mo-5% Re) to fission neutron irradiation has been investigated. These alloys were irradiated in the DR-3 reactor at Risø National Laboratory with a flux of ˜ 2.5 × 10 17 n/m 2/s ( E > 1 MeV) at ˜ 320 and 373 K toa fluence level of ˜ 1.5 × 10 24 n/m 2 ( E > 1 MeV), corresponding to ˜ 0.16 dpa (NRT). The microstructure of these materials was investigated before and after irradiation. Both unirradiated and irradiated specimens of the two alloys were tensile tested at ˜ 295 and 373 K. The fracture surfaces of both alloys in unirradiated as well as irradiated conditions were investigated by scanning electron microscopy. The main conclusion of the present investigation is that even this low dose irradiation causes a tremendous increase in tensile strength and a drastic decrease in elongation.

Singh, B. N.; Horsewell, A.; Toft, P.; Evans, J. H.

1994-09-01

267

Effect of ultrasonic treatment on tensile properties of PLA/LNR/NiZn ferrite nanocomposite  

NASA Astrophysics Data System (ADS)

The influence of sonication treatment time on the morphological and mechanical properties of LNR/PLA composite impregnated with different filler loadings of NiZn ferrite nanoparticles was investigated. The nanocomposite was prepared using melt blending method with assistance of ultrasonic treatment of 0, 1 and 2 hrs. Structural characterization of the nanocomposites was examined using scanning electron microscopy (SEM) with their elemental composition being confirmed by energy dispersive X-ray spectroscopy (EDX). The tensile properties of LNR/PLA composite treated with different ultrasonication times have improved with increasing magnetic nanofiller signature in the nanocomposite. Further, the optimum sonication time of 1 hr was found to produce nanocomposite with maximum tensile properties.

Shahdan, Dalila; Ahmad, Sahrim Hj.; Flaifel, Moayad Husein

2013-11-01

268

Studies on Tensile Properties of Eri Silk/Polyester Blended Yarn Using Design of Experiment Methodology  

NASA Astrophysics Data System (ADS)

Eri silk is one of the four varieties of silk available in India which has excellent thermal insulation property. With a view to explore its blending possibilities with polyester, manufacturing of eri/polyester blended yarn at different blend ratio in ring spinning system has been successfully performed following drawframe blending technique. The Box and Behnken design of experiment for three variables and three levels has been used to study the influence of count of the yarn spun (Ne), twist multiplier and proportion of eri fibre in the blends on some important tensile properties of the yarns produced. The chosen level of variables remaining within the industrially acceptable limits shows that fibre character and yarn parameters are the determining factors to influence yarn tensile properties. Validity of Hamburger model for the prediction of blended yarn tenacity has also been assessed for the blended yarn produced.

Choudhuri, Prabir Kumar; Majumdar, Prabal Kumar; Sarkar, Bijon

2013-03-01

269

Effect of Friction Stir Processing on Microstructure and Tensile Properties of an Investment Cast Al-7Si-0.6Mg Alloy  

NASA Astrophysics Data System (ADS)

Friction stir processing (FSP) is emerging as a promising tool for microstructural modification. The current study assesses the effects of FSP on the microstructure and mechanical properties of an investment cast Al-7Si-Mg alloy. FSP eliminates porosity and significantly refines eutectic Si particles. The extent of particle refinement varied with changes in processing conditions. A high tool rotation rate and a low-to-intermediate tool traverse speed generated a higher volume fraction of finer particles. Tensile ductility changed significantly as a result of FSP, whereas ultimate tensile strength improved only marginally. Yield strength was similar in both cast and FSP samples under various heat-treated conditions, with the highest value obtained after a T6 heat treatment. Furthermore, FSP caused significant grain refinement in the stir zone, subsequently transforming into very coarse grains as abnormal grain growth occurred during solution treatment at high temperature.

Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John A.; Grant, Glenn J.

2010-10-01

270

Microstructure and tensile properties of iron parts fabricated by selective laser melting  

NASA Astrophysics Data System (ADS)

Iron, as the basic industry material was extensively studied in the past, but it could still offer extended possibilities with the use of new processing techniques such as selective laser melting (SLM). In this work, the manufacturing of iron parts using SLM technology was investigated. The effect of processing parameters on density of the iron parts was studied. Fully dense iron parts have been fabricated at the laser power of 100 W using different laser scanning speeds. By means of metallographic observation and TEM characterization, it can be found that the grains size decreased with increasing scanning speed and high dislocation density was observed. Tensile specimens were fabricated using optimal parameters and mechanical tests allowed observing an ultimate tensile strength of 412 MPa and the yield strength of 305 MPa. Multiple self-strengthening mechanisms during SLM process are proposed to explain this high mechanical strength. The grain refinement seems to be the most significant strengthening mechanism, followed by work hardening arising from the high cooling rate.

Song, Bo; Dong, Shujuan; Deng, Sihao; Liao, Hanlin; Coddet, Christian

2014-03-01

271

Hardness and tensile strength of zircon particles and TiB 2 reinforced Al-A356.1 alloy matrix composites: comparative study  

NASA Astrophysics Data System (ADS)

Aluminum matrix composites are important engineering materials in automotive, aerospace, thermal, wear, and other applications because of excellent low weight, high specific strength, and better physical and mechanical properties compared to pure aluminum. In this paper, zircon and TiB II ceramic particles with different amounts were incorporated into Al-A356.1 alloy by stir-casting route. The ceramic particles size and adding temperature were 1 micron and 750°C respectively. Microstructure of samples has been investigated by scanning electron microscopy (SEM); hence the dispersion of reinforcement was noted. Situation of compounds of composites was examined by XRD. Mechanical tests such as hardness measurement, tensile and physical (density) tests were used. Results showed that the mechanical properties and microstructure behavior of composites have improved compared to monolithic alloy. Microstructures of the composites in as-cast conditions show uniform distribution particles and reveal better bonding in the case of zircon reinforced composite compare to TiB II, but increasing the amount of reinforcement shows better conditions in the case of TiB II reinforced composite. It is observed that TiB II reinforced composites have a better wetting condition compare to zircon reinforced composites.

Shirvani Moghaddam, K.; Abdizadeh, H.; Baharvandi, H. R.; Ehsani, N.; Abdi, F.

2007-07-01

272

Can extended photoactivation time of resin-based fissure sealer materials improve ultimate tensile strength and decrease water sorption/solubility?  

PubMed Central

Objective: This study aimed to evaluate the impact of extended photoactivation time on ultimate tensile strength (UTS), water sorption (WS) and solubility (WSB) of resin-based materials used as fissure-sealants. Methods: A fissure-sealant (Fluroshield) and a flowable composite (Permaflo) polymerized for 20 and 60 seconds were tested. For UTS, 20 hourglass shaped samples were prepared representing two materials and two photoactivation time (n=5). After 24-h dry-storage, samples were tested in tension using a universal testing machine at a cross-head speed of 0.5 mm/min (UTS was calculated in MPa). For WS and WSB, 20 disks with 5 mm diameter and 1 mm height (n=5) were prepared and volumes were calculated (mm3). They were transferred to desiccators until a constant mass was obtained (m1) and were subsequently immersed in distilled water until no alteration in mass was detected (m2). Samples were reconditioned to constant mass in desiccators (m3). WS and WSB were determined using the equations m2-m3/V and m1-m3/V, respectively. Data were subjected to two-way ANOVA and Tukey’s HSD test (P<.05). Results: There was no significant difference between materials or photoactivation times for the UTS and WS. Permaflo presented lower but negative WSB compared to Fluroshield. Conclusions: Extended photoactivation time did not improve the physical properties tested. Fluroshield presented physical properties that were similar to or better than Permaflo. PMID:23077420

Borges, Boniek Castillo Dutra; Souza-Júnior, Eduardo José; Catelan, Anderson; Paulillo, Luís Alexandre Maffei Sartini; Aguiar, Flávio Henrique Baggio

2012-01-01

273

Transverse tensile and stress rupture properties of gamma/gamma prime-delta directionally solidified eutectic  

NASA Technical Reports Server (NTRS)

Tensile and stress rupture properties were determined primarily at 760 C for specimens oriented at various angles (0 deg, 10 deg, 45 deg, and 90 deg) from the solidification direction of bars and/or slabs of the Ni-20Cb-6Cr-2.5A (gamma/gamma prime-delta) eutectic. Threaded-head specimens yielded longer rupture lives with significantly less scatter than did tapered-head specimens. Miniature specimens are suitable for determining traverse tensile and rupture properties of 1.2 centimeter diameter bar stock. The 300 hour rupture stress at 760 C for specimens oriented at 10 deg from the solidification direction was reduced from 740 to 460 MPa, and to 230 MPa for material oriented at either 45 deg or 90 deg.

Gray, H. H.

1976-01-01

274

Notch tensile properties of laser-surface-annealed 17-4 PH stainless steel in hydrogen-related environments  

Microsoft Academic Search

Slow displacement rate tensile tests were performed to determine the notched tensile strength (NTS) of 17-4 PH stainless steel with various microstructures in hydrogen-related environments. Solution-annealed (SA), peak-aged (H900), over-aged (H1025), and laser-annealed (LA) specimens were included in the study. Based on the results of NTS in air, the NTS loss in both gaseous hydrogen and H2S-saturated solution was used

L. W. Tsay; W. C. Lee; R. K. Shiue; J. K. Wu

2002-01-01

275

Improvement of tensile properties of nano-SiO 2\\/PP composites in relation to percolation mechanism  

Microsoft Academic Search

Low nano-silica loaded polypropylene composites are produced by conventional compounding technique in which the nanoparticles are grafted by polystyrene using irradiation beforehand. A high interfacial stress transfer efficiency is demonstrated by both strengthening and toughening effects perceived in tensile tests. The role of the modified nanoparticles in improvement of tensile properties of the nanocomposites is discussed in terms of percolation

Min Zhi Rong; Ming Qiu Zhang; Yong Xiang Zheng; Han Min Zeng; K Friedrich

2001-01-01

276

Prediction of Aircraft Aluminum Alloys Tensile Mechanical Properties Degradation Using Support Vector Machines  

Microsoft Academic Search

\\u000a In this paper we utilize Support Vector Machines to predict the degradation of the mechanical properties, due to surface corrosion,\\u000a of the Al 2024-T3 aluminum alloy used in the aircraft industry. Pre-corroded surfaces from Al 2024-T3 tensile specimens for\\u000a various exposure times to EXCO solution were scanned and analyzed using image processing techniques. The generated pitting\\u000a morphology and individual characteristics

Nikolaos Ampazis; Nikolaos D. Alexopoulos

2010-01-01

277

Effect of strain rate on the tensile properties of irradiated Inconel 718  

Microsoft Academic Search

The effects of strain rate on the elevated temperature tensile properties of unirradiated and irradiated Inconel 718 were determined. Irradiation conditions included total neutron fluences to 1.0 x 10²² n\\/cm² at 400°C, to 2.4 x 10²² n\\/cm² at 593°C, and 3.4 x 10²² n\\/cm² at 649°C. Test parameters included temperatures to 649°C and strain rates to 1.0 sec¹. Results show

J. M. Steichen; A. L. Ward

1976-01-01

278

Tensile properties of HVOF sprayed Inconel 625 coatings subjected aqueous corrosion  

Microsoft Academic Search

Purpose – To examine the tensile properties of high velocity oxy-fuel (HVOF) sprayed Inconel 625 coating of steel substrate before and after the aqueous corrosion. Design\\/methodology\\/approach – Workpieces were cut from steel sheets. After chemical and ultrasonic cleaning, workpiece surfaces were sand blasted and HVOF sprayed Inconel 625 coated. The coated and un-coated surfaces were subjected to the aqueous corrosion

A. Boudi; M. S. J. Hashmi; B. S. Yilbas

2006-01-01

279

CONSTITUTIONAL FACTORS AFFECTING THE TENSILE PROPERTIES OF WROUGHT ALUMINIUM-MAGNESIUM-SILICON-COPPER ALLOYS  

Microsoft Academic Search

S>The tensile properties of solution-treated and artificially aged ; alloys within the composition range 0.5 to 2.0% magnesium, 0.3 to 1.2% silicon, ; and 0 to 1.5% copper, have been investigated, and related to equilibrium ; reactions at the heat-treatment temperatures. An isotherm for the aluminum-- ; magnesium --silicon-- copper system at 520 deg C has been derived from published

D. L. W

1958-01-01

280

Effect of Surface Treatment on the Flexural Strength of Denture Base Resin and Tensile Strength of Autopolymerizing Silicone Based Denture Liner Bonded to Denture Base Resin: An In Vitro Study  

Microsoft Academic Search

Silicone based denture liners are superior to acrylic based denture liners but it has a problem of failure of adhesion with\\u000a the denture base. To evaluate the effect on the tensile bond strength of silicone based liner and flexural strength of denture\\u000a base resin when the latter is treated with different chemical etchants prior to the application of the resilient

Saloni Gupta

2010-01-01

281

Peripheral nerves in the rat exhibit localized heterogeneity of tensile properties during limb movement  

PubMed Central

Peripheral nerves in the limbs stretch to accommodate changes in length during normal movement. The aim of this study was to determine how stretch is distributed along the nerve relative to local variations in mechanical properties. Deformation (strain) in joint and non-joint regions of rat median and sciatic nerves was measured in situ during limb movement using optical image analysis. In each nerve the strain was significantly greater in the joint rather than the non-joint regions (2-fold in the median nerve, 5- to 10-fold in the sciatic). In addition, this difference in strain was conserved in the median nerve ex vivo, demonstrating an in-built longitudinal heterogeneity of mechanical properties. Tensile testing of isolated samples of joint and non-joint regions of both nerves showed that joint regions were less stiff (more compliant) than their non-joint counterparts with joint: non-joint stiffness ratios of 0.5 ± 0.07 in the median nerve, and 0.8 ± 0.02 in the sciatic. However, no structural differences identified at the light microscope level in fascicular/non-fascicular tissue architecture between these two nerve regions could explain the observed tensile heterogeneity. This identification of localized functional heterogeneity in tensile properties is particularly important in understanding normal dynamic nerve physiology, provides clues to why peripheral nerve repair outcomes are variable, and suggests potential novel therapeutic targets. PMID:15064329

Phillips, JB; Smit, X; De Zoysa, N; Afoke, A; Brown, RA

2004-01-01

282

Dynamic Tensile Properties of Iron and Steels for a Wide Range of Strain Rates and Strain  

NASA Astrophysics Data System (ADS)

The tensile stress-strain curves of iron and a variety of steels, covering a wide range of strength level, over a wide strain rate range on the order of 10-3 ~ 103 s-1, were obtained systematically by using the Sensing Block Type High Speed Material Testing System (SBTS, Saginomiya). Through intensive analysis of these results, the strain rate sensitivity of the flow stress for the large strain region, including the viscous term at high strain rates, the true fracture strength and the true fracture strain were cleared for the material group of the ferrous metals. These systematical data may be useful to develop a practical constitutive model for computer codes, including a fracture criterion for simulations of the dynamic behavior in crash worthiness studies and of work-pieces subjected to dynamic plastic working for a wide strain rate range.

Kojima, Nobusato; Hayashi, Hiroyuki; Yamamoto, Terumi; Mimura, Koji; Tanimura, Shinji

283

Microstructure evolution and tensile properties of Zr-2.5 wt.% Nb pressure tubes processed from billets with different microstructures  

SciTech Connect

Pressurized heavy water reactors (PHWR) use zirconium-base alloys for their low neutron-absorption cross section, good mechanical strength, low irradiation creep, and high corrosion resistance in reactor atmospheres. Starting with identical ingots, billets having different microstructures were obtained by three different processing methods for fabrication of Zr-2.5 wt%Nb pressure tubes., The billets were further processed by hot extrusion and cold Pilger tube reducing to the finished product. Microstructural characterization was done at each stage of processing. The effects of the initial billet microstructure on the intermediate and final microstructure and mechanical property results were determined. It was found that the structure at each stage and the final mechanical properties depend strongly on the initial billet microstructure. The structure at the final stage consists of elongated alpha zirconium grains with a network of metastable beta zirconium phase. Some of this metastable phase transforms into stable beta niobium during thermomechanical processing. Billets with quenched structure resulted in less beta niobium at the final stage. The air cooled billets resulted in a large amount of beta niobium. The tensile properties, especially the percentage elongation, were found to vary for the different methods. Higher percentage elongation was observed for billets having quenched structure. Extrusion and forging did not produce any characteristic differences in the properties. The results were used to select a process flow sheet which yields the desired mechanical properties with suitable microstructure in the final product.

Kapoor, K.; Saratchandran, N. [NDT, Hyderabad (India). Quality Assurance Group] [NDT, Hyderabad (India). Quality Assurance Group; Muralidharan, K. [Defense Metallurgical Research Lab., Hyderabad (India)] [Defense Metallurgical Research Lab., Hyderabad (India)

1999-02-01

284

Investigation of the C-ring test for measuring hoop tensile strength of nuclear grade ceramic composites  

NASA Astrophysics Data System (ADS)

Silicon carbide (SiC) and silicon carbide fiber reinforced composites (SiC/SiCf) are currently being evaluated as a high temperature material for use in nuclear reactors. While methods to determine the mechanical properties of SiC/SiCf on planar test specimens are well established, mechanical testing methods for tubular SiC/SiCf are still being developed. In this study the C-ring test is evaluated for use with nuclear grade SiC/SiCf as a method of measuring hoop strength. For the samples tested in this work, hoop strengths from C-ring testing are shown to agree within 6% to those obtained using expanding plug testing and analysis shows that the expected composite behavior is observed during testing. While other techniques may give more accurate values for hoop stress, the small specimen requirements and ease of testing makes C-ring testing a valuable tool.

Jacobsen, G. M.; Stone, J. D.; Khalifa, H. E.; Deck, C. P.; Back, C. A.

2014-09-01

285

Effects of Long-Term Thermal Exposure on Commercially Pure Titanium Grade 2 Elevated-Temperature Tensile Properties  

NASA Technical Reports Server (NTRS)

Elevated-temperature tensile testing of commercially pure titanium (CP Ti) Grade 2 was conducted for as-received commercially produced sheet and following thermal exposure at 550 and 650 K (531 and 711 F) for times up to 5000 h. The tensile testing revealed some statistical differences between the 11 thermal treatments, but most thermal treatments were statistically equivalent. Previous data from room temperature tensile testing was combined with the new data to allow regression and development of mathematical models relating tensile properties to temperature and thermal exposure. The results indicate that thermal exposure temperature has a very small effect, whereas the thermal exposure duration has no statistically significant effects on the tensile properties. These results indicate that CP Ti Grade 2 will be thermally stable and suitable for long-duration space missions.

Ellis, David L.

2012-01-01

286

Correlation between strength properties in standard test specimens and molded phenolic parts  

NASA Technical Reports Server (NTRS)

This report describes an investigation of the tensile, flexural, and impact properties of 10 selected types of phenolic molding materials. The materials were studied to see in what ways and to what extent their properties satisfy some assumptions on which the theory of strength of materials is based: namely, (a) isotropy, (b) linear stress-strain relationship for small strains, and (c) homogeneity. The effect of changing the dimensions of tensile and flexural specimens and the span-depth ratio in flexural tests were studied. The strengths of molded boxes and flexural specimens cut from the boxes were compared with results of tests on standard test specimens molded from the respective materials. The nonuniformity of a material, which is indicated by the coefficient of variation, affects the results of tests made with specimens of different sizes and tests with different methods of loading. The strength values were found to depend on the relationship between size and shape of the molded specimen and size and shape of the fillers. The most significant variations observed within a diversified group of materials were found to depend on the orientation of fibrous fillers. Of secondary importance was the dependence of the variability of test results on the pieces of filler incorporated into the molding powder as well as on the size of the piece. Static breaking strength tests on boxes molded from six representative phenolic materials correlated well with falling-ball impact tests on specimens cut from molded flat sheets. Good correlation was obtained with Izod impact tests on standard test specimens prepared from the molding materials. The static breaking strengths of the boxes do not correlate with the results of tensile or flexural tests on standard specimens.

Turner, P S; Thomason, R H

1946-01-01

287

Effect of hydrogen and oxygen on the tensile properties of V 4Cr 4Ti  

NASA Astrophysics Data System (ADS)

Flat subsized tensile specimens of the vanadium alloy V-4Cr-4Ti were loaded with different amounts of pure hydrogen in order to study its effect on room temperature tensile properties. It was found that, apart from a slight influence of pretreatment, hydrogen can be tolerated up to about 2.5 at.%, whereas higher hydrogen contents lead to catastrophic failure. It is suggested that this behavior is attributed to coexistence of dissolved hydrogen and brittle hydride at room temperature. In addition, some measurements were made with specimens that had been loaded with about 850 wppm oxygen from a low oxygen partial pressure at 500°C (773 K), prior to hydrogen exposure. In this case room temperature ductility, starting from a decreased level, suffered severe deterioration by hydrogen concentrations of much less than 1 at.%. Apparently, in this case, embrittlement is concentrated at the near-surface grain boundaries, and stresses can no longer be absorbed if the matrix gets hardened by the addition of hydrogen. Thus, under the given conditions, oxygen and hydrogen show a strong synergistic effect on the tensile properties of this material.

Röhrig, H. D.; DiStefano, J. R.; Chitwood, L. D.

1998-10-01

288

Low-energy electron effects on tensile modulus and infrared transmission properties of a polypyromellitimide film  

NASA Technical Reports Server (NTRS)

Infrared (IR) spectroscopy and tensile modulus testing were used to evaluate the importance of experimental procedure on changes in properties of pyromellitic dianhydride-p,p prime-oxydianiline film exposed to electron radiation. The radiation exposures were accelerated, approximate equivalents to the total dose expected for a 30 year mission in geosynchronous Earth orbit. The change in the tensile modulus depends more on the dose rate and the time interval between exposure and testing than on total dose. The IR data vary with both total dose and dose rate. A threshold dose rate exists below which reversible radiation effects on the IR spectra occur. Above the threshold dose rate, irreversible effects occur with the appearance of a new band. Post-irradiation and in situ IR absorption bands are significantly different. It is suggested that the electron radiation induced metastable, excites molecular states.

Ferl, J. E.; Long, E. R., Jr.

1981-01-01

289

Tensile properties of 21-6-9 stainless steel at elevated temperatures  

SciTech Connect

Tensile properties of Type 21-6-9 austenitic stainless steel were measured at temperatures ranging from ambient to 1200C at a strain rate of 6.67 {times} 10{sup {minus}4} s{sup {minus}1}. Data show that yield stress decreases rapidly from room temperature to about 300C, followed by a nearly constant value in the `plateau` region from 300 to 600C. Beyond the ``plateau,`` there is more rapid drop in yield stress as temperature increases. Ultimate tensile stress shows a plateau between 300 and 700 C, which may be caused by solutes. 21-6-9 stainless steel has excellent ductility, with the elongation to failure ranging from 55 to 95%. It appears that there is a local minimum in the ductility at approximately 700C. Results are compared with earlier results of Kassner and co-workers.

Torres, S.G.; Henshall, G.A.

1993-10-01

290

Effect of Neutron Irradiation on Tensile Properties of Unidirectional Silicon Carbide Composites  

SciTech Connect

Tensile properties of uni-directionally reinforced Hi-Nicalon EType S SiC fiber, chemically vapor-infiltrated (CVI) SiC-matrix composites, with either pyrolytic carbon (PyC) or multilayered PyC/SiC interphase, were characterized following neutron irradiations to the maximum fluence of 7.7x1025 n/m2 at 380 and 800 C. The stress - strain behavior of the multilayered interphase composites remained unmodified after irradiation. The PyC interphase composite increased in ultimate tensile stress and strain to failure following neutron irradiation, whereas the proportional limit stress exhibited a slight decrease. Potential mechanisms for these changes include accommodation of misfit stress through irradiation creep, reduced interfacial friction, and differential swelling among individual composite constituents.

Katoh, Yutai [ORNL; Nozawa, Takashi [ORNL; Snead, Lance Lewis [ORNL; Hinoki, Tatsuya [ORNL

2007-01-01

291

Influence of Prior Fatigue Damage on Tensile Properties of 316L(N) Stainless Steel and Modified 9Cr-1Mo Steel  

NASA Astrophysics Data System (ADS)

In the current study, the effect of prior low-cycle fatigue (LCF) damage on the tensile properties of 316L(N) stainless steel (SS) and modified 9Cr-1Mo steel were systematically investigated. The LCF tests were interrupted at 5, 10, 30, and 50 pct of the total fatigue life followed by tensile tests on the same specimens at the same strain rate (3 × 10-3 s-1) and temperatures of 300 K, 823 K, and 873 K (27 °C, 550 °C, and 600 °C). Prior strain cycling at elevated temperatures had remarkable effect on the tensile properties of both cyclically hardening and cyclically softening materials. An exponential relationship between the yield stress and the amount of pre-strain cycles is obtained for both the materials. The initial drastic change in the yield strength values up to 10 pct of fatigue life may be due to the microstructural changes that lead to hardening or softening in 316L(N) SS and modified 9Cr-1Mo steel, respectively. Saturation in the yield strength values beyond 10 pct of fatigue life has practical importance for remnant fatigue life assessment. Evolution of fatigue damage in both the 316L(N) SS and modified 9Cr-1Mo steel was analyzed using the surface replica technique.

Mariappan, K.; Shankar, Vani; Sandhya, R.; Mathew, M. D.; Bhaduri, A. K.

2014-12-01

292

Influence of Prior Fatigue Damage on Tensile Properties of 316L(N) Stainless Steel and Modified 9Cr-1Mo Steel  

NASA Astrophysics Data System (ADS)

In the current study, the effect of prior low-cycle fatigue (LCF) damage on the tensile properties of 316L(N) stainless steel (SS) and modified 9Cr-1Mo steel were systematically investigated. The LCF tests were interrupted at 5, 10, 30, and 50 pct of the total fatigue life followed by tensile tests on the same specimens at the same strain rate (3 × 10-3 s-1) and temperatures of 300 K, 823 K, and 873 K (27 °C, 550 °C, and 600 °C). Prior strain cycling at elevated temperatures had remarkable effect on the tensile properties of both cyclically hardening and cyclically softening materials. An exponential relationship between the yield stress and the amount of pre-strain cycles is obtained for both the materials. The initial drastic change in the yield strength values up to 10 pct of fatigue life may be due to the microstructural changes that lead to hardening or softening in 316L(N) SS and modified 9Cr-1Mo steel, respectively. Saturation in the yield strength values beyond 10 pct of fatigue life has practical importance for remnant fatigue life assessment. Evolution of fatigue damage in both the 316L(N) SS and modified 9Cr-1Mo steel was analyzed using the surface replica technique.

Mariappan, K.; Shankar, Vani; Sandhya, R.; Mathew, M. D.; Bhaduri, A. K.

2015-02-01

293

Tensile Properties and Small-Angle Neutron Scattering Investigation of Stereoblock Elastomeric Polypropylene  

SciTech Connect

Elastomeric polypropylene (ePP) produced from unbridged 2-arylindene metallocene catalysts was studied by uniaxial tensile and small-angle neutron scattering (SANS) techniques. The ePP can be separated into three fractions by successive boiling-solvent fractionation method to yield: a low-tacticity fraction soluble in ether (ES), an intermediate-tacticity fraction soluble in heptane (HS), and a high-tacticity fraction insoluble in heptane (HI). Tensile properties of ePP were compared to its solvent fractions, and the role of each solvent fraction residing within ePP was investigated by blending 5 weight % deuterated fraction with ePP. The tensile properties of each fraction vary considerably, exhibiting properties from a weak gum elastomer for ES, to a semi-crystalline thermoplastic for HI. The intermediate-tacticity HS fraction exhibits elastic properties similar to the parent elastomer (ePP). In the melt at 160 C, SANS shows that all deuterated fractions are homogeneously mixed with ePP in a one-phase system. At 25 C upon a slow cooling from the melt, the low-tacticity fraction is preferentially segregated in the amorphous domains induced by different crystallization temperatures and kinetics of the deuterated ES and high-tacticity components. The high-tacticity component within ePP (dHI-ePP) retains its plastic properties in the blend. Despite its low crystallinity ({le} 2%), the low-tacticity fraction can co-crystallize with the crystalline matrix. The dES-ePP shows little or no relaxation when held under strain and recovers readily upon the release of stress.

Pople, John A

2002-08-06

294

In Vitro Comparison of Compressive and Tensile Strengths ofAcrylic Resins Reinforced by Silver Nanoparticles at 2% and0.2% Concentrations  

PubMed Central

Background and aims. Polymethyl methacrylate, PMMA, is widely used in prosthodontics for fabrication of removable prostheses. This study was undertaken to investigate the effect of adding silver nanoparticles (AgNPs) to PMMA at 2% and 0.2% concentrations on compressive and tensile strengths of PMMA. Materials and methods. The silver nanoparticles were mixed with heat-cured acrylic resin in an amalgamator in two groups at 0.2 and 2 wt% of AgNPs. Eighteen 2×20×200-mm samples were prepared for tensile strength test, 12 samples containing silver nanoparticle and 6 samples for the control group. Another 18 cylindrical 25×38-mm samples were prepared for compressive strength test. Scanning electron microscopy was used to verify homogeneous distribution of particles. The powder was manually mixed with a resin monomer and then the mixture was properly blended. Before curing, the paste was packed into steel molds. After curing, the specimens were removed from the molds. One-way ANOVA was used for statistical analysis, followed by multiple comparison test (Scheffé’s test). Results. This study showed that the mean compressive strength of PMMA reinforced with AgNPs was significantly higher than that of the unmodified PMMA (P<0.05). It was not statistically different between the two groups reinforced with AgNPs. The tensile strength was not significantly different between the 0.2% group and unmodified PMMA and it de-creased significantly after incorporation of 2% AgNPs (P<0.05). Conclusion. Based on the results and the desirable effect of nanoparticles of silver on improvement of compressive strength of PMMA, use of this material with proper concentration in the palatal area of maxillary acrylic resin dentures is recommended. PMID:25587381

Ghaffari, Tahereh; Hamedirad, Fahimeh; Ezzati, Baharak

2014-01-01

295

Influence of thermo-mechanical treatment on the tensile properties of a modified 14Cr-15Ni stainless steel  

NASA Astrophysics Data System (ADS)

The titanium modified 14Cr-15Ni austenitic stainless steel is used as clad and wrapper material for fast breeder nuclear reactor. Thermo-mechanical treatments consisting of solution annealing at two different temperatures of 1273 and 1373 K followed by cold-work and thermal ageing have been imparted to the steel to tailor its microstructure for enhancing strength. Tensile tests have been carried out on the thermo-mechanically treated steel at nominal strain rate of 1.6 × 10-4 s-1 over a temperature range of 298-1073 K. The yield stress and the ultimate tensile strength of the steel increased with increase in solution treatment temperature and this has been attributed to the fine and higher density of Ti(C,N) precipitate. Tensile flow behaviour of the steel has been analysed using Ludwigson and Voce constitutive equations. The steel heat treated at higher solution temperature exhibited earlier onset of cross slip during tensile deformation. The rate of recovery at higher test temperatures was also influenced by variations in solution heat treatment temperature. In addition, dynamic recrystallization during tensile deformation at higher temperatures was profound for steel solution heat-treated at lower temperature. The differences in flow behaviour and softening mechanisms during tensile testing of the steel after different heat treated conditions have been attributed to the nature of Ti(C,N) precipitation.

Vijayanand, V. D.; Laha, K.; Parameswaran, P.; Nandagopal, M.; Panneer Selvi, S.; Mathew, M. D.

2014-10-01

296

Predictions of the Mechanical Properties and Microstructure Evolution of High Strength Steel in Hot Stamping  

NASA Astrophysics Data System (ADS)

Hot stamping is an innovative operation in metal-forming processes which virtually avoids the cracking and wrinkling of high strength steel (HSS) sheets. Examining the phase transformation and mechanical properties of HSS by means of experiments is challenging. In this article, a numerical model of the hot stamping process including forming, quenching, and air cooling was developed to reveal the microstructure evolution and to predict the final mechanical properties of hot-stamped components after multi-process cycles. The effects of the number of process cycles and the holding times on the temperature of HSS were examined using the model. The microstructure evolution of HSS under variable holding times is illustrated. The mechanical properties, particularly hardness and tensile strength, were predicted. It was found that the martensitic content increased with increasing holding time, and the martensitic content of the formed component at the flange and end was higher than for the sidewall, and lowest for the bottom. The hardness trend was consistent with the martensitic content. After six process cycles, the predictive errors of the model for hardness and tensile strength were acceptable for practical applications in engineering. Comparison between the predicted results and the experiment results showed that the developed model was reliable.

Cui, Junjia; Lei, Chengxi; Xing, Zhongwen; Li, Chunfeng; Ma, Shumei

2012-11-01

297

A novel in situ device based on a bionic piezoelectric actuator to study tensile and fatigue properties of bulk materials.  

PubMed

In this work, a miniaturized device based on a bionic piezoelectric actuator was developed to investigate the static tensile and dynamic fatigue properties of bulk materials. The device mainly consists of a bionic stepping piezoelectric actuator based on wedge block clamping, a pair of grippers, and a set of precise signal test system. Tensile and fatigue examinations share a set of driving system and a set of signal test system. In situ tensile and fatigue examinations under scanning electron microscope or metallographic microscope could be carried out due to the miniaturized dimensions of the device. The structure and working principle of the device were discussed and the effects of output difference between two piezoelectric stacks on the device were theoretically analyzed. The tensile and fatigue examinations on ordinary copper were carried out using this device and its feasibility was verified through the comparison tests with a commercial tensile examination instrument. PMID:24985848

Wang, Shupeng; Zhang, Zhihui; Ren, Luquan; Zhao, Hongwei; Liang, Yunhong; Zhu, Bing

2014-06-01

298

A novel in situ device based on a bionic piezoelectric actuator to study tensile and fatigue properties of bulk materials  

NASA Astrophysics Data System (ADS)

In this work, a miniaturized device based on a bionic piezoelectric actuator was developed to investigate the static tensile and dynamic fatigue properties of bulk materials. The device mainly consists of a bionic stepping piezoelectric actuator based on wedge block clamping, a pair of grippers, and a set of precise signal test system. Tensile and fatigue examinations share a set of driving system and a set of signal test system. In situ tensile and fatigue examinations under scanning electron microscope or metallographic microscope could be carried out due to the miniaturized dimensions of the device. The structure and working principle of the device were discussed and the effects of output difference between two piezoelectric stacks on the device were theoretically analyzed. The tensile and fatigue examinations on ordinary copper were carried out using this device and its feasibility was verified through the comparison tests with a commercial tensile examination instrument.

Wang, Shupeng; Zhang, Zhihui; Ren, Luquan; Zhao, Hongwei; Liang, Yunhong; Zhu, Bing

2014-06-01

299

Effect of neutron irradiation on tensile properties of materials for pressure vessel internals of WWER type reactors  

NASA Astrophysics Data System (ADS)

Tensile properties of austenitic stainless steels used for pressure vessel internals of WWER type reactors (18Cr-10Ni-Ti steel and its weld metal) in the initial and irradiated conditions were investigated. Based on the presented original investigations and generalization of the available experimental data the dependences of yield strength and ultimate strength on a neutron damage dose up to 108 dpa, irradiation temperature range 320-450 °C and test temperature range 20-450 °C were obtained. The method of determination of the stress-strain curve parameters was proposed which does not require uniform elongation of a specimen as an input parameter. The dependences was proposed allowing one to calculate the stress-strain curve parameters for 18Cr-10Ni-Ti steel and its weld metal for different test temperatures, different irradiation temperatures and doses. The dependences were obtained to describe the fracture strain decrease under irradiation at a temperature range 320-340 °C when irradiation swelling is absent.

Sorokin, A. A.; Margolin, B. Z.; Kursevich, I. P.; Minkin, A. J.; Neustroev, V. S.

2014-01-01

300

Effects of heat input on microstructure and tensile properties of laser welded magnesium alloy AZ31  

SciTech Connect

A 3 kW CO{sub 2} laser beam was used to join wrought magnesium alloy AZ31 sheets, and the effects of heat input on the quality of butt welding joints were studied. By macro and microanalysis, it is found that the welding heat input plays an important role in laser welding process for AZ31 wrought sheets. After welding, the grains far from the weld centre present the typical rolled structure. But the microstructure out of the fusion zone gradually changes to complete equiaxed crystals as the distance from the weld centre decreases. Adjacent to the fusion boundary, there is a band region with columnar grains, and its growth direction is obviously perpendicular to the solid/liquid line. The microstructure in fusion centre consists of fine equiaxed grains and the many precipitated particles are brittle phase Mg{sub 17}Al{sub 12} or Mg{sub 17}(Al,Zn){sub 12}. With increasing the heat input, the band width of columnar grains varies, the grains in fusion zone get coarser, and the distribution of precipitates changes from intragranularly scattered particles to intergranularly packed ones. The results of tensile test show that the change trend of ultimate tensile strength (UTS) and elongation of the welded joints is to increase at first and then decrease with the heat input increasing. When the heat input reaches 24 J mm{sup -1}, the maximum value of the UTS is up to 96.8% of the base metal.

Quan, Y.J. [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China)], E-mail: quanyj_2006@yahoo.com.cn; Chen, Z.H.; Gong, X.S.; Yu, Z.H. [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

2008-10-15

301

The Effect of Artificial Aging on the Tensile Properties of Alclad 24S-T and 24S-T Aluminum Alloy  

NASA Technical Reports Server (NTRS)

An experimental study was made to determine the effect of artificial aging on the tensile properties of alclad 24S-T and 24S-T aluminum-alloy sheet material. The results of the tests show that certain combinations of aging time and temperature cause a marked increase in the yield strength and a small increase in the ultimate strength; these increases are accompanied by a very large decrease in elongation. A curve is presented that shows the maximum yield strengths that can be obtained by aging this material at various combinations of time and temperature. The higher values of yield stress are obtained in material aged at relatively longer times and lower temperatures.

Kotanchik, Joseph N.; Woods, Walter; Zender, George W.

1943-01-01

302

Thermal Stability and Tensile Properties of Electrodeposited Cu-Bi Alloy  

NASA Astrophysics Data System (ADS)

By means of pulse electrodeposition technique, a nanocrystalline Cu-0.42at.%Bi alloy with a grain size down to ~10 nm was synthesized. The thermal stability of Cu-Bi electrodeposit was investigated using differential scanning calorimetry (DSC), x-ray diffraction (XRD), transmission electron microscopy (TEM), and hardness measurements. The temperature at which this material tends to become unstable was found to be 160 °C. DSC revealed an exothermal peak between 190 and 300 °C, caused by grain growth. It was observed that segregation of Bi at grain boundary has a considerable effect on the thermal stability of the Cu-Bi alloy. Tensile test showed the sample interestingly possesses a high strength of 760 MPa, while no plastic strain is detected.

Chen, Xianhua; Mao, Jianjun

2011-04-01

303

Compressive and Tensile Properties of Tungsten-Continuous-Fiber-Reinforced Zr-Based Amorphous Alloy Matrix Composite Fabricated by Liquid Pressing Process  

NASA Astrophysics Data System (ADS)

In the present study, a Zr-based amorphous alloy matrix composite reinforced with tungsten continuous fibers was fabricated without pores or defects by a liquid pressing process; the microstructures and mechanical properties of the fibers were investigated. Approximately 60 vol pct of the fibers was distributed inside the amorphous matrix, although the matrix of the composite also contained a small number of polygonal crystalline phases. The tensile strength of the composite was about 30 pct higher than that of the amorphous alloy, because of the very strong reinforcement of the tungsten fibers and because of the strong fiber/matrix interfacial bonding. The shear fracture of the amorphous matrix was significantly constrained by the fibers, and fracture proceded almost perpendicular to the tensile direction. According to the compressive test results of the composite, fracture did not take place as a one-time occurrence after the maximum strength point, but proceeded as the loading was sustained by the fibers, thereby leading to a maximum strength of 2477 MPa and a plastic strain of 1.5 pct. The fibers played an important role in improving the ductility, by interrupting the propagation of shear cracks initiated at the amorphous matrix and by taking over a considerable number of compressive loads in the area in which the cracks were formed, while the fibers themselves were buckled. These findings suggested that the liquid pressing process was useful for the development of amorphous matrix composites with improved mechanical properties.

Lee, Kyuhong; Lee, Sang-Bok; Lee, Sang-Kwan; Lee, Sunghak

2008-06-01

304

Friction, wear, and tensile properties of vacuum hot pressing crosslinked UHMWPE/nano-HAP composites.  

PubMed

Ultra high molecular weight polyethylene (UHMWPE) is a thermoplastic engineering plastic with excellent mechanical properties. In this study, nonirradiated and irradiated UHMWPE/nano-hydroxyapatite (nano-HAP) composites were prepared by vacuum hot-pressing method, and then friction, wear, and tensile properties were investigated. To explore mechanisms of these properties, differential scanning calorimetry, infrared spectrum, and scanning electron microscopy with energy dispersive spectrometry analysis were carried out on the samples. The results in this study indicated that reduced friction coefficients and wear rate could be obtained when nonirradiated and irradiated UHMWPE were filled with 7% nano-HAP. The irradiated UHMWPE/7% nano-HAP also had a synergistic function of wear reduction as compared with irradiated UHMWPE and nonirradiated UHMWPE/7% nano-HAP. Samples filled with 7% nano-HAP showed a brittle fracture behavior, and a linear relationship between modulus and crystallinity for a nonirradiated and irradiated sample was found in this study. PMID:21598380

Xiong, Lei; Xiong, Dangsheng; Yang, Yuanyuan; Jin, Jiabo

2011-07-01

305

An in vitro Comparative Evaluation of Micro Tensile Bond Strength of Two metal bonding Resin Cements bonded to Cobalt Chromium alloy  

PubMed Central

Background: The purpose of this study was to evaluate and compare the micro tensile bond strength of two metal bonding resin cements to sandblasted cobalt chromium alloy. Materials & Methods: Eight, Cobalt chromium alloy blocks of dimensions 10x5x5 mm were cast, finished and polished. One of the faces of each alloy block measuring 5x5mm was sandblasted with 50 ?m grit alumina particles. The alloy blocks were then cleaned in an ultrasonic cleaner for 1 min and then air dried with an air stream. The Sandblasted surfaces of the two alloy blocks were bonded together with 2 different metal bonding resin systems (Panavia F Kuraray and DTK Kleber – Bredent). The samples were divided into 2 groups (n=4). Group 1- Two Co-Cr blocks were luted with Panavia cement. Group 2- Two Co-Cr blocks were luted with DTK Kleber-Bredent cement. The bonded samples were cut with a diamond saw to prepare Microtensile bars of approximately 1mm x 1mm x 6mm. Thirty bars from each group were randomly separated into 2 subgroups (n=15) and left for 3hrs (baseline) as per manufacturer's instructions while the other group was aged for 24hrs in 370C water, prior to loading to failure under tension at a cross head speed of 1mm/min. Failure modes were determined by means of stereomicroscopy (sm). Statistical analysis was performed through one way – ANOVA. Results: Significant variation in micro-tensile bond strength was observed between the two metal bonding resin systems. Conclusion: DTK showed higher mean bond strength values than Panavia F cement both at baseline and after aging. How to cite this article: Musani S, Musani I, Dugal R, Habbu N, Madanshetty P, Virani D. An in vitro Comparative Evaluation of Micro Tensile Bond Strength of Two metal bonding Resin Cements bonded to Cobalt Chromium alloy. J Int Oral Health 2013;5(5):73-8. PMID:24324308

Musani, Smita; Musani, Iqbal; Dugal, Ramandeep; Habbu, Nitin; Madanshetty, Pallavi; Virani, Danish

2013-01-01

306

Data on Material Properties and Panel Compressive Strength of a Plastic-bonded Material of Glass Cloth and Canvas  

NASA Technical Reports Server (NTRS)

Results are presented of tests for determining the tensile, compressive, and bending properties of a material of plastic-bonding glass cloth and canvas layers. In addition, 10 panel specimens were tested in compression. Although the material is not satisfactory for primary structural use in aircraft when compared on a strength-weight basis with other materials in common use, there appears to be potential strength in the material that will require research for development. These points are considered in some detail in the concluding discussion of the report. An appendix shows that a higher tensile strength can be obtained by changes in the type of weave used in the glass-cloth reinforcement.

Zender, George W; Schuette, Evan H; Weinberger, Robert A

1944-01-01

307

Solar Effects on Tensile and Optical Properties of Hubble Space Telescope Silver-Teflon(Registered Trademark) Insulation  

NASA Technical Reports Server (NTRS)

A section of the retrieved Hubble Space Telescope (HST) solar array drive arm (SADA) multilayer insulation (MLI), which experienced 8.25 years of space exposure, was analyzed for environmental durability of the top layer of silver-Teflon (DuPont) fluorinated ethylene propylene (Ag-FEP). Because the SADA MLI had solar and anti-solar facing surfaces and was exposed to the space environment for a long duration, it provided a unique opportunity to study solar effects on the environmental degradation of Ag-FEP, a commonly used spacecraft thermal control material. Data obtained included tensile properties, solar absorptance, surface morphology and chemistry. The solar facing surface was found to be extremely embrittled and contained numerous through-thickness cracks. Tensile testing indicated that the solar facing surface lost 60% of its mechanical strength and 90% of its elasticity while the anti-solar facing surface had ductility similar to pristine FEP. The solar absorptance of both the solar facing surface (0.155 plus or minus 0.032) and the anti-solar facing surface (0.208 plus or minus 0.012) were found to be greater than pristine Ag-FEP (0.074). Solar facing and anti-solar facing surfaces were microscopically textured, and locations of isolated contamination were present on the anti-solar surface resulting in increased localized texturing. Yet, the overall texture was significantly more pronounced on the solar facing surface indicating a synergistic effect of combined solar exposure and increased heating with atomic oxygen erosion. The results indicate a very strong dependence of degradation, particularly embrittlement, upon solar exposure with orbital thermal cycling having a significant effect.

deGroh, Kim, K.; Dever, Joyce A.; Snyder, Aaron; Kaminski, Sharon; McCarthy, Catherine E.; Rapoport, Alison L.; Rucker, Rochelle N.

2006-01-01

308

Influence of Specimen Preparation and Specimen Size on the Transverse Tensile Strength and Scatter of Glass Epoxy Laminates  

NASA Technical Reports Server (NTRS)

The influence of specimen polishing, specimen configuration, and specimen size on the transverse tension strength of two glass epoxy materials loaded in three and four point bending was evaluated. Polishing machined edges, and/or tension side failure surfaces, was detrimental to specimen strength characterization instead of yielding a higher, more accurate, strength as a result of removing inherent manufacture and handling flaws. Transverse tension strength was sensitive to span length due to the classical weakest link effect. However, strength was less sensitive to volume changes achieved by increasing specimen width. The Weibull scaling law over-predicted changes in transverse tension strengths in three point bend tests and under-predicted changes in transverse tension strengths in four point bend tests. Furthermore, the Weibull slope varied with specimen configuration, volume, and sample size. Hence, the utility of this scaling law for predicting transverse tension strength is unclear.

OBrien, T. Kevin; Chawan, Arun D.; DeMarco, Kevin

1999-01-01

309

The Relationships Between Microstructure, Tensile Properties and Fatigue Life in Ti-5Al-5V-5Mo-3Cr-0.4Fe (Ti-5553)  

NASA Astrophysics Data System (ADS)

beta-titanium alloys are being increasingly used in airframes as a way to decrease the weight of the aircraft. As a result of this movement, Ti-5Al-5V-5Mo-3Cr-0.4Fe (Timetal 555), a high-strength beta titanium alloy, is being used on the current generation of landing gear. This alloy features good combinations of strength, ductility, toughness and fatigue life in alpha+beta processed conditions, but little is known about beta-processed conditions. Recent work by the Center for the Accelerated Maturation of Materials (CAMM) research group at The Ohio State University has improved the tensile property knowledge base for beta-processed conditions in this alloy, and this thesis augments the aforementioned development with description of how microstructure affects fatigue life. In this work, beta-processed microstructures have been produced in a Gleeble(TM) thermomechanical simulator and subsequently characterized with a combination of electron and optical microscopy techniques. Four-point bending fatigue tests have been carried out on the material to characterize fatigue life. All the microstructural conditions have been fatigue tested with the maximum test stress equal to 90% of the measured yield strength. The subsequent results from tensile tests, fatigue tests, and microstructural quantification have been analyzed using Bayesian neural networks in an attempt to predict fatigue life using microstructural and tensile inputs. Good correlation has been developed between lifetime predictions and experimental results using microstructure and tensile inputs. Trained Bayesian neural networks have also been used in a predictive fashion to explore functional dependencies between these inputs and fatigue life. In this work, one section discusses the thermal treatments that led to the observed microstructures, and the possible sequence of precipitation that led to these microstructures. The thesis then describes the implications of microstructure on fatigue life and implications of tensile properties on fatigue life. Several additional experiments are then described that highlight possible causes for the observed dependence of microstructure on fatigue life, including fractographic evidence to provide support of microstructural dependencies.

Foltz, John W., IV

310

Optical Measurements of Vocal Fold Tensile Properties: Implications for Phonatory Mechanics  

PubMed Central

In voice research, in vitro tensile stretch experiments of vocal fold tissues are commonly employed to determine the tissue biomechanical properties. In the standard stretch-release protocol, tissue deformation is computed from displacements applied to sutures inserted through the thyroid and arytenoid cartilages, with the cartilages assumed to be rigid. Here, a non-contact optical method was employed to determine the actual tissue deformation of vocal fold lamina propria specimens from three excised human larynges in uniaxial tensile tests. Specimen deformation was found to consist not only of deformation of the tissue itself, but also deformation of the cartilages, as well as suture alignment and tightening. Stress-stretch curves of a representative load cycle were characterized by an incompressible Ogden model. The initial longitudinal elastic modulus was found to be considerably higher if determined based on optical displacement measurements than typical values reported in the literature. The present findings could change the understanding of the mechanics underlying vocal fold vibration. Given the high longitudinal elastic modulus the lamina propria appeared to demonstrate a substantial level of anisotropy. Consequently, transverse shear could play a significant role in vocal fold vibration, and fundamental frequencies of phonation should be predicted by beam theories accounting for such effects. PMID:21497355

Kelleher, Jordan E.; Siegmund, Thomas; Chan, Roger W.; Henslee, Erin A.

2011-01-01

311

Optical measurements of vocal fold tensile properties: implications for phonatory mechanics.  

PubMed

In voice research, in vitro tensile stretch experiments of vocal fold tissues are commonly employed to determine the tissue biomechanical properties. In the standard stretch-release protocol, tissue deformation is computed from displacements applied to sutures inserted through the thyroid and arytenoid cartilages, with the cartilages assumed to be rigid. Here, a non-contact optical method was employed to determine the actual tissue deformation of vocal fold lamina propria specimens from three excised human larynges in uniaxial tensile tests. Specimen deformation was found to consist not only of deformation of the tissue itself, but also deformation of the cartilages, as well as suture alignment and tightening. Stress-stretch curves of a representative load cycle were characterized by an incompressible Ogden model. The initial longitudinal elastic modulus was found to be considerably higher if determined based on optical displacement measurements than typical values reported in the literature. The present findings could change the understanding of the mechanics underlying vocal fold vibration. Given the high longitudinal elastic modulus the lamina propria appeared to demonstrate a substantial level of anisotropy. Consequently, transverse shear could play a significant role in vocal fold vibration, and fundamental frequencies of phonation should be predicted by beam theories accounting for such effects. PMID:21497355

Kelleher, Jordan E; Siegmund, Thomas; Chan, Roger W; Henslee, Erin A

2011-06-01

312

The theoretical strength of rubber: numerical simulations of polyisoprene networks at high tensile strains evidence the role of average chain tortuosity  

NASA Astrophysics Data System (ADS)

The ultimate stress and strain of polyisoprene rubber were studied by numerical simulations of three-dimensional random networks, subjected to tensile strains high enough to cause chain rupture. Previously published molecular chain force extension models and a numerical network construction procedure were used to perform the simulations for network crosslink densities between 2 × 1019 and 1 × 1020 cm-3, corresponding to experimental dicumyl-peroxide concentrations of 1-5 parts per hundred. At tensile failure (defined as the point of maximum stress), we find that the fraction of network chains ruptured is between 0.1% and 1%, depending on the crosslink density. The fraction of network chains that are taut, i.e. their end-to-end distance is greater than their unstretched contour length, ranges between 10% and 15% at failure. Our model predicts that the theoretical (defect-free) failure stress should be about twice the highest experimental value reported. For extensions approaching failure, tensile stress is dominated by the network morphology and purely enthalpic bond distortion forces and, in this regime, the model has essentially no free parameters. The average initial chain tortuosity (?) appears to be an important statistical property of rubber networks; if the stress is scaled by ? and the tensile strain is scaled by ?-1, we obtain a master curve for stress versus strain, valid for all crosslink densities. We derive an analytic expression for the average tortuosity, which is in agreement with values calculated in the simulations.

Hanson, David E.; Barber, John L.

2013-10-01

313

TRPV4 channel activation improves the tensile properties of self-assembled articular cartilage constructs  

PubMed Central

A persistent hurdle in the field of tissue regeneration is to produce tissues with biochemical and biomechanical properties robust enough to meet the aggressive physiological demands of the native milieu. In an effort to improve these properties, tissues grown in vitro are often subjected to mechanical stimuli that aim to recapitulate in vivo physiology. These mechanical stimuli are thought to produce downstream alterations in intracellular ion concentrations, which ultimately give rise to increased biosynthesis. There is mounting evidence that these perturbations in the cellular microenvironment are regulated by the Ca(2+)-permeable transient receptor potential vanilloid 4 (TRPV4) channel. In this study, we examined the effects of targeted TRPV4 activation on self-assembled articular cartilage constructs. The objectives of this study were 1) to determine whether TRPV4 activation would enhance self-assembled constructs, 2) to identify an optimal treatment time window for TRPV4 activation, and 3) to compare TRPV4 activation to Na(+)/K(+) pump inhibition, which has been shown previously to improve construct tensile properties. This study employed a two-phased approach. In Phase I, self-assembled constructs were grown for 4 weeks and subjected to treatment with the TRPV4 agonist 4alpha-phorbol-12,13-didecanoate (4alpha-PDD) during three treatment time windows: t=6-10 days, t=10-14 days, and t=14-18 days. Treatment during t=10-14 days produced an 88% increase in collagen and a 153% increase in tensile stiffness. This treatment window was carried forward to Phase II. In Phase II, we performed a head-to-head comparison between TRPV4 activation using 4alpha-PDD and Na(+)/K(+) pump inhibition using ouabain. Treatment with 4alpha-PDD produced improvements on par with ouabain (91% to 107% increases in tensile stiffness). The results of this study demonstrate the effectiveness of ion channel modulation as a strategy for improving engineered tissues. To our knowledge, this is the first study to examine TRPV4 channel activation in tissue engineering. PMID:23128162

Eleswarapu, Sriram V.; Athanasiou, Kyriacos A.

2012-01-01

314

Charpy toughness and tensile properties of a neutron irradiated stainless steel submerged-arc weld cladding overlay  

SciTech Connect

The possibility of stainless steel cladding increasing the resistance of an operating nuclear reactor pressure vessel to extension of surface flaws is highly dependent upon the irradiated properties of the cladding. Therefore, weld overlay cladding irradiated at temperatures and fluences relevant to power reactor operation was examined. The cladding was applied to a pressure vessel steel plate by the submerged-arc, single-wire, oscillating electrode method. Three layers of cladding were applied to provide a cladding thickness adequate for fabrication of test specimens. The first layer was type 309, and the upper two layers were type 308 stainless steel. There was considerable dilution of the type 309 in the first layer of cladding as a result of excessive melting of the base plate. Specimens for the irradiation study were taken from near the base plate/cladding interface and also from the upper layers of cladding. Charpy V-notch and tensile specimens were irradiated at 288/sup 0/C to neutron fluences of 2 x 10/sup 23/ n/m/sup 2/ (E > 1 MeV). When irradiated, both types 308 and 309 cladding showed a 5 to 40% increase in yield strength accompanied by a slight increase in ductility in the temperature range from 25 to 288/sup 0/C. All cladding exhibited ductile-to-brittle transition behavior during impact testing.

Corwin, W.R.; Berggren, R.G.; Nanstad, R.K.

1984-01-01

315

An open-end burst test method to obtain uniaxial hoop tensile properties of fuel cladding in a hot cell  

NASA Astrophysics Data System (ADS)

The hoop stress-hoop strain relationship of fuel cladding is one of the essential input parameters for safety analysis of fuel rods. The three objectives of this paper were: to propose a burst test method for open-end tube specimens with the uniaxial hoop stress condition; to develop the necessary in-cell high temperature open-end burst (OEB) techniques to implement the method; and to determine the optimum specimen length for the proposed OEB test method. Silicone oil was selected as the pressurization medium, and it was sealed inside the specimens not by welding but by O-rings so that no axial tensile stress was induced in the specimens. The specimens with combined end plugs and O-rings were successfully assembled by manipulators in a hot cell, and a high temperature (?350 °C), high pressure (?100 MPa) seal was achieved. The optimum specimen length was determined by using ductile and embrittled tubes with various lengths of 30-60 mm and was found to be around 45 mm for typical BWR fuel rods. During the OEB test, internal pressure and diametral expansion were monitored to obtain the basic mechanical performance properties of the fuel cladding such as yield stress, ultimate strength, as well as the true hoop stress-hoop strain curve.

Nakatsuka, Masafumi; Aita, Makoto; Sakamoto, Kan; Higuchi, Toru

2013-03-01

316

Thermal degradation of the tensile properties of undirectionally reinforced FP-Al2O3/EZ 33 magnesium composites  

NASA Technical Reports Server (NTRS)

The effects of isothermal and cyclic exposure on the room temperature axial and transverse tensile strength and dynamic flexural modulus of 35 volume percent and 55 volume percent FP-Al203/EZ 33 magnesium composites were studied. The composite specimens were continuously heated in a sand bath maintained at 350 C for up to 150 hours or thermally cycled between 50 and 250 C or 50 and 350 C for up to 3000 cycles. Each thermal cycle lasted for a total of six minutes with a hold time of two minutes at the maximum temperature. Results indicate no significant loss in the room temperature axial tensile strength and dynamic flexural modulus of composites thermally cycled between 50 and 250 C or of composites isothermally heated at 350 C for up to 150 hours from the strength and modulus data for the untreated, as-fabricated composites. In contrast, thermal cycling between 50 and 350 C caused considerable loss in both room temperature strength and modulus. Fractographic analysis and measurement of composite transverse strength and matrix hardness of thermally cycled and isothermally heated composites indicated matrix softening and fiber/matrix debonding due to void growth at the interface and matrix cracking as the likely causes of the strength and modulus loss behavior. Previously announced in STAR as N82-21260

Bhatt, R.T.; Grimes, H. H.

1983-01-01

317

Thermal degradation of the tensile properties of undirectionally reinforced FP-AI203/EZ 33 magnesium composites  

NASA Technical Reports Server (NTRS)

The effects of isothermal and cyclic exposure on the room temperature axial and transverse tensile strength and dynamic flexural modulus of 35 volume percent and 55 volume percent FP-Al2O3/EZ 33 magnesium composites were studied. The composite specimens were continuously heated in a sand bath maintained at 350 C for up to 150 hours or thermally cycled between 50 and 250 C or 50 and 350 C for up to 3000 cycles. Each thermal cycle lasted for a total of six minutes with a hold time of two minutes at the maximum temperature. Results indicate to significant loss in the room temperature axial tensile strength and dynamic flexural modulus of composites thermally cycled between 50 and 250 C or of composites isothermally heated at 350 C for up to 150 hours from the strength and modulus data for the untreated, as fabricated composites. In contrast, thermal cycling between 50 and 350 C caused considerable loss in both room temperature strength and modulus. Fractographic analysis and measurement of composite transverse strength and matrix hardness of thermally cycled and isothermally heated composites indicated matrix softening and fiber/matrix debonding due to void growth at the interface and matrix cracking as the likely causes of the strength and modulus loss behavior.

Bhatt, R. T.; Grimes, H. H.

1982-01-01

318

The effect of hydrogen as a temporary alloying element on the microstructure and tensile properties of Ti-6Al-4V  

NASA Astrophysics Data System (ADS)

Ti-6Al-4V alloy, to which 0.6 wt pct to 1.0 wt pct (22 to 33 at. pct) hydrogen has been added, can undergo a phase transformation which produces unique, fine microstructures. Specimens of the alloy were heated to 870°C, transformed at temperatures between 540°C and 700°C, and the microstructures were determined as a function of hydrogen content and transformation temperature. Microstructures and tensile properties of sheet specimens were determined after such transformation followed by dehydrogenation at temperatures between 650°C and 760°C. The highest yield strength (1130 MPa) and good ductility (9 pct El) were associated with a fine equiaxed microstructure obtained in material charged with approximately 1.0 wt pct hydrogen, transformed at 565°C and dehydrogenated at 675°C. Lower strengths and ductilities were associated with acicular microstructures produced by transformation at higher temperatures or coarser structures producted at higher dehydrogenation temperatures.

Kerr, William R.

1985-06-01

319

Tensile properties of latex paint films with TiO2 pigment  

NASA Astrophysics Data System (ADS)

The tensile properties of latex paint films containing TiO2 pigment were studied with respect to temperature, strain-rate and moisture content. The purpose of performing these experiments was to assist museums in defining safe conditions for modern paintings held in collections. The glass transition temperature of latex paint binders is in close proximity to ambient temperature, resulting in high strain-rate dependence in typical exposure environments. Time dependence of modulus and failure strain is discussed in the context of time-temperature superposition, which was used to extend the experimental time scale. Nonlinear viscoelastic material models are also presented, which incorporate a Prony series with the Ogden or Neo-Hookean hyperelastic function for different TiO2 concentrations.

Hagan, Eric W. S.; Charalambides, Maria N.; Young, Christina T.; Learner, Thomas J. S.; Hackney, Stephen

2009-05-01

320

Effect of Zr content and mechanical working on the structure and tensile properties of AA8090 alloy plates  

Microsoft Academic Search

Aluminium–lithium (Al–Li)-based alloy, equivalent to AA8090 specification, was cast and processed to 12–90mm thick semi-finished products by upset forging and rolling. Increasing the Zr content within the AA8090 specification from ?0.06 to ?0.12% resulted in refinement of the as-cast grain structure, and improvement in in-plane and short transverse tensile properties.The in-plane tensile properties of the wrought products increased, while the

Amol A. Gokhale; Vijaya Singh

2005-01-01

321

Effects of Mn Addition on Tensile and Charpy Impact Properties in Austenitic Fe-Mn-C-Al-Based Steels for Cryogenic Applications  

NASA Astrophysics Data System (ADS)

Effects of Mn addition (17, 19, and 22 wt pct) on tensile and Charpy impact properties in three austenitic Fe-Mn-C-Al-based steels were investigated at room and cryogenic temperatures in relation with deformation mechanisms. Tensile strength and elongation were not varied much with Mn content at room temperature, but abruptly decreased with decreasing Mn content at 77 K (-196 °C). Charpy impact energies at 273 K (0 °C) were higher than 200 J in the three steels, but rapidly dropped to 44 J at 77 K (-196 °C) in the 17Mn steel, while they were higher than 120 J in the 19Mn and 22Mn steels. Although the cryogenic-temperature stacking fault energies (SFEs) were lower by 30 to 50 pct than the room-temperature SFEs, the SFE of the 22Mn steel was situated in the TWinning-induced plasticity regime. In the 17Mn and 19Mn steels, however, ?'-martensites were formed by the TRansformation-induced plasticity mechanism because of the low SFEs. EBSD analyses along with interrupted tensile tests at cryogenic temperature showed that the austenite was sufficiently deformed in the 19Mn steel even after the formation of ?'-martensite, thereby leading to the high impact energy over 120 J.

Lee, Junghoon; Sohn, Seok Su; Hong, Seokmin; Suh, Byeong-Chan; Kim, Sung-Kyu; Lee, Byeong-Joo; Kim, Nack J.; Lee, Sunghak

2014-11-01

322

The Strength Properties and Frictional Behaviour of Brittle Solids  

Microsoft Academic Search

An experimental study has been made of the friction and strength properties of crystalline materials such as rock-salt, lead sulphide and ice. From frictional measurements on rock-salt and from estimates of the real area of contact during sliding, the specific shear strength of the material at the rubbing interface is calculated and found to be nearly seven times as great

R. F. King; D. Tabor

1954-01-01

323

Incorporating Turbula mixers into a blending scale-up model for evaluating the effect of magnesium stearate on tablet tensile strength and bulk specific volume.  

PubMed

Turbula bottle blenders are often used in lab-scale experiments during early-stage pharmaceutical product development. Unfortunately, applying knowledge gained with these blenders to larger-sized diffusion mixers is limited by the lack of blending models that include Turbula mixers. To address this need for lubrication blending scale-up, 2:1 blends of microcrystalline cellulose and spray-dried lactose or dibasic calcium phosphate were mixed with 1% magnesium stearate using Turbula bottle blenders, varying bottle volume, V (30-1250mL); bottle headspace fraction, F(headspace) (30-70%); and the number of blending cycles, r (24 to ?190,000 cycles). The impact of lubrication blending on tensile strength and bulk specific volume quality attributes, QA, was modeled by:where QA(0) is initial QA value, ? is sensitivity of QA to lubrication, ? is formulation-specific lubrication rate constant, and L is characteristic mixing length scale (i.e. 1.5V(1/3) for Turbula blenders, V(1/3) for simple diffusion mixers). The factor of 1.5 captures the bottle dimensions and the more complex mixing dynamics of the Turbula blender. This lubrication blending process model is valid for scale-up from 30-mL to 200-L blenders. Assessing bulk specific volume may provide a simpler, more material-sparing means for determining ? than tensile strength, since these QAs exhibited similar ? values. PMID:22405966

Kushner, Joseph

2012-06-15

324

Tensile and Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials  

NASA Technical Reports Server (NTRS)

This paper represents a status report documenting the work on creep of superalloys performed under Project Prometheus. Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, are being screened to compare their respective capabilities for impeller applications. Several wrought superalloys including Hastelloy X, (Haynes International, Inc., Kokomo, IN), Inconel 617, Inconel 740, Nimonic 263, and Incoloy MA956 (Special Metals Corporation, Huntington, WV) are also being screened to compare their capabilities for duct applications. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Conventional tensile and creep tests were performed at temperatures up to 1200 K on specimens extracted from the materials. Initial microstructure evaluations were also undertaken.

Gabb, Timothy P.; Gayda, John

2006-01-01

325

Tensile impact properties of vanadium-base alloys irradiated at <430{degree}C.  

SciTech Connect

Tensile and impact properties were investigated at <430 C on V-Cr-Ti, V-Ti-Si, and V-Ti alloys after irradiation to {approx}2-46 dpa at 205-430 C in lithium or helium in the Fast Flux Test Facility (FFTF), High Flux Isotope Reactor (HFIR), Experimental Breeder Reactor II (EBR-II), and Advanced Test Reactor (ATR). A 500-kg heat of V-4Cr-4Ti exhibited high ductile-brittle transition temperature and minimal uniform elongation as a result of irradiation-induced loss of work-hardening capability. Work-hardening capabilities of 30- and 100-kg heats of V-4Cr-4Ti varied significantly with irradiation conditions, although the 30-kg heat exhibited excellent impact properties after irradiation at {approx}390-430 C. The origin of the significant variations in the work-hardening capability of V-4Cr-4Ti is not understood, although fabrication variables, annealing history, and contamination from the irradiation environment are believed to play important roles. A 15-kg heat of V-3Ti-1Si exhibited good work-hardening capability and excellent impact properties after irradiation at {approx}390-430 C. Helium atoms, either charged dynamically or produced via transmutation of boron in the alloys, promote work-hardening capability in V-4Cr-4Ti and V-3Ti-1Si.

Chung, H. M.

1998-05-18

326

Hydrogen effects on the tensile properties of 21-6-9 stainless steel  

Microsoft Academic Search

The effect of hydrogen on the mechanical properties of a series of nineteen experimental heats of 21-6-9 stainless steel was\\u000a investigated. The nineteen material groups covered a variety of forging processes, strength levels, grain sizes, and microstructures.\\u000a The data show that absorbed hydrogen acts as an interstitial strengthener which increases the flow stress of 21-6-9 similar\\u000a to the effects of

McIntyre R. Louthan

1982-01-01

327

Compressive and tensile failure at high fluid pressure where preexisting fractures have cohesive strength, with application to the San Andreas fault  

USGS Publications Warehouse

In thrusting and strike-slip situations, when the maximum principal horizontal stress S1 acts nearly normal to a fault (a misoriented fault, such as the San Andreas), pore-fluid pressure > the lithostatic load, Pf > Sv, is required to reactivate movement on that fault. Pf > Sv may be achieved without causing hydraulic tensile fracturing if (1) previously existing cracks have regained cohesive strength by chemical processes, (2) subcritical crack growth has been blunted, and (3) the least principal horizontal stress S3 nearly equals Sv. Where Pf > Sv has been attained within a misaligned fault, increasing the stress difference (S1 - S3) at constant Pf > Sv will not lead to shear failure, while a decrease in (S1 - S3) can lead to shear failure of that fault. However, where the cohesive strength of material in a broad misaligned fault zone is less than that of the surrounding intact rock, increasing (S1 - S3) while Pf > Sv can result in shear failure of fractures at near optimum angles to S1, but confined within this weak fault zone. If this faulting results in the local short-lived attainment of Pf > Sv (cataclastic deformation and frictional heating overcoming dilation) and a simultaneous decrease in (S1 - S3), this combination of effects can trigger movement along the main trace of the misaligned fault. When increasing Pf results in hydraulic failure, anisotropy in tensile strength or fracture toughness resulting from foliation within faults allows fractures to propagate along the planes of weakness rather than across the foliation perpendicular to S3.

Fournier, R.O.

1996-01-01

328

Physical aging of plastoferrites under tensile stress and its effect on microwave properties  

NASA Astrophysics Data System (ADS)

Aging phenomena in soft viscoelastic materials have been used as an important tool to investigate the physics of complexity for both scientific and practical purposes. At ambient conditions, microwave frequency-domain spectroscopy (gigahertz-FDS) is employed to investigate the electromagnetic properties at continuum length scales for two commercial plastoferrites (PFs) subjected to a uniaxial tension during a long time t of application. PFs are an attractive prototype for investigating the interactions between polarization and magnetization phenomena, and time. For both PFs we have measured simultaneously the time evolution of the effective complex permittivity ? =?'-j?? and magnetic permeability ? =?'-j?? spectra during tensile-loading experiments. These changes allow a determination of how physical aging affects the microwave properties of PFs with tensile elongation in the range of 3%-17% on the time scale of hundreds of hours. At short times of strain application the ? and ? measurements under stress can be explained in terms of a Gaussian molecular network model (affine behavior) in the limit of low strain. However, the large-strain mechanical response does show nonaffine behavior. The key achievement is that we present observational evidence for a three-stage aging in which ("zone I") ?' and ?? increase as the ln(t) and reach a peak value at tI, then ("zone II") there is a slower decrease in ?' and ???-ln(t) as time moves from tI up to tII, and finally, ("zone III") as time moves to higher values, ?' and ?? saturate for long times. We have provided experimental evidence that, while tI is found to be constant with the initial elongation ratio ?0 that is applied to the PF sample, the data revealed that tII??0. In sharp contrast, there is no significant change in ?' and ?? as a function of the elongation ratio. It can be argued that the decoupling of the dielectric properties from the magnetic properties may be regarded as a consequence of rigidity of the ferrite grains. To probe the influence of aging that alters the initial morphology of the PF samples, scanning electron microscopy (SEM) was used. The results of the SEM studies indicate the existence of cracks at the PF surface and disagglomeration of the ferrite grains. A tentative phenomenological model is proposed to explain the three-stage evolution of the elasticity network which has been tracked by gigahertz-FDS during the isothermal application of tension. Because the structure of soft materials is scale dependent, the response to a mechanical load also depends on the length and time scales of the probing excitation. We argued that the effective permittivity increase during stage I can be attributed to the electric dipole reorientation with respect to the direction of the polarization under the tensile stress applied to the material. The physical mechanism driving the effective permittivity decrease in stage II is thought to be a consequence of the breakup of the adsorbed ferrite particle network due to the detachment of chains from the surface of the particles. Stage III reflects the eventual stable steady state for which local stresses are redistributed in the elasticity network of the filled polymer under strain. The understanding of the physical aging mechanisms is significant because it can offer a strategy for materials selection and PF-based device performance optimization.

Brosseau, C.; NDong, W.

2008-09-01

329

Effect of fiber treatments on tensile and thermal properties of starch/ethylene vinyl alcohol copolymers/coir biocomposites  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effects of different fiber treatments, namely washing with water, alkali treatment (mercerization) and bleaching, on mechanical and thermal properties of starch/EVA/coir biocomposites were evaluated by tensile tests and thermogravimetry (TG), respectively. Additionally, the fiber/matrix interfac...

330

Influence of the chemical composition of flux on the microstructure and tensile properties of submerged-arc welds  

Microsoft Academic Search

A study was conducted on the effect of flux composition for the microstructure and tensile properties of a submerged-arc welded AISI 1025 steel. Three flux compositions were used with a low-carbon electrode. A commercial flux composition was used for comparison. The welding conditions were kept the same. Tension tests were pursued at room temperature. Microstructure and macrostructure of welds were

Ana Ma. Paniagua-Mercado; Victor M. López-Hirata; Maribel L. Saucedo Muñoz

2005-01-01

331

Notch effects on room temperature tensile and bend properties of Ni3Al and Ni3Al+B  

NASA Technical Reports Server (NTRS)

The notched mechanical properties of Ni3Al and Ni3Al+B prepared by powder metallurgy techniques have been determined in both tension and bending at room temperature. Tensile tests performed using double-notched specimens containing relatively blunt notches produced intergranular fracture in both Ni3Al and Ni3Al+B, with evidence of fracture initiating in an intergranular manner ahead of the blunt notch in both cases. Estimates of notched fracture toughness from bend tests and of local grain boundary fracture stress from the notched tensile tests suggest an increase in these values with boron addition.

Khadkikar, P. S.; Rigney, J. D.; Lewandowski, J. J.; Vedula, K.

1989-01-01

332

Dynamic Tensile Properties of Engineering Plastics over a Wide Range of Strain Rates  

NASA Astrophysics Data System (ADS)

Engineering plastics are used widely in the field of production of motor vehicles, electromotive tools and others. Most part of plastics has a remarkable strain rate dependency on the flow stress. It is, therefore, required to make clear the strain rate dependency of plastics over a wide range of strain rates on the order from 10-2 s-1 to 103 s-1, and to make use of these properties for the simulation of the behavior of crashing parts of automobiles and of work-pieces under dynamic plastic working. In this paper, dynamic tensile properties of polyamide, polycarbonate, polypropylene, and ABS plastic were studied over the wide range of strain rate. The strain-rate dependencies of these tested plastics were made clear quantitatively. The strain rate sensitivity of the flow stress, for a group of plastics whose elastic modulus does not depend significantly on the strain rates, is expressed clearly by using the constitutive model as a special case of Tanimura-Mimura model 2009 (T-M 2009). The rate sensitivity of the flow stress, for another group of plastics whose elastic modulus depends obviously on the strain rates, is also expressed with high accuracy by using the T-M 2009.

Tsuda, Toru; Hayashi, Hiroyuki; Yamamoto, Terumi; Abe, Atsushi; Tanimura, Shinji

333

Postirradiation tensile properties of Mo and Mo alloys irradiated with 600 MeV protons  

NASA Astrophysics Data System (ADS)

Tensile specimens of pure Mo and Mo-5 Re, Mo-41 Re and TZM alloys have been irradiated with 600 MeV protons in the PIREX facility at 300 and 660 K to 0.5 dpa. Results of the postirradiation tensile testing show a strong radiation hardening and a severe loss of ductility for all the materials tested at room temperature.

Müller, G. V.; Gavillet, D.; Victoria, M.; Martin, J. L.

1994-09-01

334

Dynamic Tensile Loading Improves the Functional Properties of Mesenchymal Stem Cell-Laden Nanofiber-Based Fibrocartilage  

PubMed Central

Fibrocartilaginous tissues such as the meniscus serve critical load-bearing roles, relying on arrays of collagen fibers to resist tensile loads experienced with normal activity. As these structures are frequently injured and possess limited healing capacity, there exists great demand for tissue-engineered replacements. Toward recreating the structural features of these anisotropic tissues in vitro, we employ scaffolds composed of co-aligned nanofibers that direct mesenchymal stem cell (MSC) orientation and the formation of organized extracellular matrix (ECM). Concomitant with ECM synthesis, the mechanical properties of constructs increase with free-swelling culture, but ultimately failed to achieve equivalence with meniscal fibrocartilage. As mechanical forces are essential to the development and maintenance of musculoskeletal tissues, this work examined the effect of cyclic tensile loading on MSC-laden nanofibrous constructs. We hypothesized that loading would modulate the transcriptional behavior of MSCs, spur the deposition of ECM, and lead to enhancements in construct mechanical properties compared to free-swelling controls. Fiber-aligned scaffolds were seeded with MSCs and dynamically loaded daily in tension or maintained as nonloaded controls for 4 weeks. With mechanical stimulation, fibrous gene expression increased, collagen deposition increased, and the tensile modulus increased by 16% relative to controls. These results show that dynamic tensile loading enhances the maturation of MSC-laden aligned nanofibrous constructs, suggesting that recapitulation of the structural and mechanical environment of load-bearing tissues results in increases in functional properties that can be exploited for tissue engineering applications. PMID:21247342

Baker, Brendon M.; Shah, Roshan P.; Huang, Alice H.

2011-01-01

335

The mechanical and strength properties of diamond  

NASA Astrophysics Data System (ADS)

Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of materials based on carbon, namely the fullerenes and graphines have been identified in recent years and are now the subject of intense research.

Field, J. E.

2012-12-01

336

The mechanical and strength properties of diamond.  

PubMed

Diamond is an exciting material with many outstanding properties; see, for example Field J E (ed) 1979 The Properties of Diamond (London: Academic) and Field J E (ed) 1992 The Properties of Natural and Synthetic Diamond (London: Academic). It is pre-eminent as a gemstone, an industrial tool and as a material for solid state research. Since natural diamonds grew deep below the Earth's surface before their ejection to mineable levels, they also contain valuable information for geologists. The key to many of diamond's properties is the rigidity of its structure which explains, for example, its exceptional hardness and its high thermal conductivity. Since 1953, it has been possible to grow synthetic diamond. Before then, it was effectively only possible to have natural diamond, with a small number of these found in the vicinity of meteorite impacts. Techniques are now available to grow gem quality synthetic diamonds greater than 1 carat (0.2 g) using high temperatures and pressures (HTHP) similar to those found in nature. However, the costs are high, and the largest commercially available industrial diamonds are about 0.01 carat in weight or about 1 mm in linear dimension. The bulk of synthetic diamonds used industrially are 600 µm or less. Over 75% of diamond used for industrial purposes today is synthetic material. In recent years, there have been two significant developments. The first is the production of composites based on diamond; these materials have a significantly greater toughness than diamond while still maintaining very high hardness and reasonable thermal conductivity. The second is the production at low pressures by metastable growth using chemical vapour deposition techniques. Deposition onto non-diamond substrates was first demonstrated by Spitsyn et al 1981 J. Cryst. Growth 52 219-26 and confirmed by Matsumoto et al 1982 Japan J. Appl. Phys. 21 L183-5. These developments have added further to the versatility of diamond. Two other groups of materials based on carbon, namely the fullerenes and graphines have been identified in recent years and are now the subject of intense research. PMID:23168381

Field, J E

2012-12-01

337

Microstructural Features Controlling Mechanical Properties in Nb-Mo Microalloyed Steels. Part I: Yield Strength  

NASA Astrophysics Data System (ADS)

Low carbon Nb-Mo microalloyed steels show interesting synergies between the "micro"-alloying elements when high strength-high toughness properties are required. Strain accumulation in austenite is enhanced, and therefore grain sizes are refined in the final microstructures. The presence of Mo facilitates the presence of non-polygonal phases, and this constituent modification induces an increment in strength through a substructure formation as well as through an increase in the dislocation density. Regarding fine precipitation and its strengthening effect, the mean size of NbC is reduced in the presence of Mo and their fraction increased, thus enhancing their contribution to yield strength. In this paper, a detailed characterization of the microstructural features of a series of microalloyed steels is described using the electron-backscattered diffraction technique. Mean crystallographic unit sizes, a grain boundary misorientation analysis, and dislocation density measurements are performed. Transmission electron microscopy is carried out to analyze the chemical composition of the precipitates and to estimate their volume fraction. In this first part, the contribution of different strengthening mechanisms to yield strength is evaluated and the calculated value is compared to tensile test results for different coiling temperatures and compositions.

Isasti, Nerea; Jorge-Badiola, Denis; Taheri, Mitra L.; Uranga, Pello

2014-10-01

338

High-temperature properties and microstructure of Mo microalloyed ultra-high-strength steel  

NASA Astrophysics Data System (ADS)

The high-temperature mechanical properties and microstructure of forging billets of C-Si-Mn-Cr and C-Si-Mn-Cr-Mo ultra-high-strength cold-rolled steels (tensile strength?1000 MPa, elongation?10%) were studied. Through the comparison of reduction in area and hot deformation resistance at 600-1300°C, the Mo-containing steel was found to possess a higher strength and a better plasticity than the Mo-free one. The equilibrium phase diagram and atom fraction of Mo in different phases at different temperatures were calculated by Thermo-Calc software (TCW). The results analyzed by using transmission electron microscopy and TCW show that precipitates in the Mo-containing steel are primarily M23C6, which promote pearlite formation. The experimental data also show that a lower ductility point existing in the Mo-free steel at 850°C is eliminated in the Mo-containing one. This is mainly due to the segregation of Mo at grain boundaries investigated by electron probe microanalysis (EPMA), which improves the strength of grain boundaries.

Han, Qi-Hang; Kang, Yong-Lin; Zhao, Xian-Meng; Gao, Lu-Feng; Qiu, Xue-Song

2011-08-01

339

Time/Temperature Dependent Tensile Strength of SiC and Al2O3-Based Fibers  

NASA Technical Reports Server (NTRS)

In order to understand and model the thermomechanical behavior of fiber-reinforced composites, stress-rupture, fast-fracture, and warm-up rupture studies were conducted on various advanced SiC and Al2O3-based fibers in the,temperature range from 20 to 1400 C in air as well as in inert environments. The measured stress-rupture, fast fracture, and warm-up rupture strengths were correlated into a single master time/temperature-dependent strength plot for each fiber type using thermal activation and slow crack growth theories. It is shown that these plots are useful for comparing and selecting fibers for CMC and MMC reinforcement and that, in comparison to stress rupture tests, the fast-fracture and warm-up tests can be used for rapid generation of these plots.

Yun, Hee Mann; DiCarlo, James A.

1997-01-01

340

Effects of build orientation on tensile strength for stereolithography-manufactured ASTM D-638 type I specimens  

Microsoft Academic Search

A statistical design of experiments (DOE) approach was used to determine if specific build orientation parameters impacted\\u000a mechanical strength of stereolithography (SL) fabricated parts. A single platform (25.4 × 25.4-cm cross-section) on the 3D\\u000a Systems Viper si2 SL machine was designed to hold 18 ASTM D-638 type I samples manufactured in different orientations. The\\u000a DOE tested three factors: axis, layout,

Rolando Quintana; Jae-Won Choi; Karina Puebla; Ryan Wicker

2010-01-01

341

Effect of hydrogen on tensile properties of martenistic steels for fusion application  

NASA Astrophysics Data System (ADS)

The present work is aimed at giving a contribution to the characterisation of hydrogen embrittlement (HE) resistance of two martensitic steels, i.e. the modified F 82 H and the MANET. The study is based on tensile low strain rate tests, conducted on notched cylindrical specimens which were previously charged with hydrogen. In the case of modified F 82 H steel, two different heat treatments were considered, i.e. the as-received (AR) and the aged condition. The results of the tests indicated that the analysed steels show a noticeable reduction of the area reduction coefficient ( Z%), even for rather low global hydrogen content. As an example, 1-2 wppm are sufficient to lower the Z% of mod. F 82 H to 14-18%, from the 35-40% value typical of the virgin material. In the paper, these results are discussed with the aid of microstructural investigations and SEM analysis which allowed to characterise the microstructural properties of the materials.

Beghini, M.; Benamati, G.; Bertini, L.; Valentini, R.

1998-10-01

342

Parametric Study on the Tensile Properties of Ni-Based Alloy for a VHTR  

NASA Astrophysics Data System (ADS)

A very high-temperature reactor (VHTR) has been studied among generation IV nuclear power plants owing to its many advantages such as high-electric efficiency and massive hydrogen production. The material used for the heat exchanger should sustain structural integrity for its life even though the material is exposed to a harsh environment at 1223 K (950 °C) in an impure helium coolant. Therefore, an enhancement of the material performance at high temperature gives a margin in determining the operating temperature and life time. This work is an effort to find an optimum combination of alloying elements and processing parameters to improve the material performance. The tensile property and microstructure for nickel-based alloys fabricated in a laboratory were evaluated as a function of the heat treatment, cold working, and grain boundary strengthener using a tension test at 1223 K (950 °C), scanning electron microscopy, and transmission electron microscopy. Elongation to rupture was increased by additional heat treatment and cold working, followed by additional heat treatment in the temperature range from 1293 K to 1383 K (1020 °C to 1110 °C) implying that the intergranular carbide contributes to grain boundary strengthening. The temperature at which the grain boundary is improved by carbide decoration was higher for a cold-worked specimen, which was described by the difference in carbide stability and carbide formation kinetics between no cold-worked and cold-worked specimens. Zr and Hf played a scavenging effect of harmful elements causing an increase in ductility.

Kim, Dong-Jin; Jung, Su Jin; Mun, Byung Hak; Kim, Sung Woo; Lim, Yun Soo

2015-01-01

343

NIOBIUM-CLAD 304L STAINLESS STEEL PEMFC BIPOLAR PLATE MATERIAL: TENSILE AND BEND PROPERTIES  

SciTech Connect

Niobium (Nb)-clad 304L stainless steel (SS) is currently under consideration for use as a bipolar plate material in polymer electrolyte membrane fuel cell (PEMFC) stacks. Because metal bipolar plates will likely be formed by stamping, the sheet metal properties of this material were characterized in both the as-rolled and an optimized annealed condition via a series of bend and quasi-static tensile tests. Results from tensile testing demonstrate that annealing significantly softens and thereby improves the ductility of the material. Bend test results indicate that springback is nearly independent of the bend direction relative to rolling direction for both the as-rolled and annealed conditions. In the as-rolled condition, springback is also nearly independent of specimen orientation (i.e. whether the cladding layer is on the inside or outside of the bend). However in the annealed condition, springback does depend on the cladding orientation relative to bending and was found in all cases to be substantially lower than that observed in the as-rolled condition. Microstructural analysis of the specimens indicates that two failure conditions can potentially arise, dependent on the thermomechanical condition of the material. In the as-rolled condition, failure initiates via fracture through the Nb cladding. In the annealed specimens, failure can occur by brittle fracture of an interfacial intermetallic layer that forms during the annealing treatment. This generates a series of crack-induced pores along the interface between the Nb cladding and the SS core, which eventually leads to ductile failure of the Nb cladding via localized necking. However the conditions required for this phenomenon to take place are fairly extreme and can be readily avoided in practice. In general, the results suggest that to achieve acceptable stamping tolerances, the material should be annealed prior to forming and the bipolar plate flow channel pattern should be designed such that extreme levels of strain at the cladding/core interface are avoided to mitigate the potential for partial delamination within the material.

Hong, Sung-tae; Weil, K. Scott

2007-06-01

344

Influence of weak layer heterogeneity and slab properties on slab tensile failure propensity and avalanche release area  

NASA Astrophysics Data System (ADS)

Dry-snow slab avalanches are generally caused by a sequence of fracture processes including failure initiation in a weak snow layer underlying a cohesive slab followed by crack propagation within the weak layer (WL) and tensile fracture through the slab. During past decades, theoretical and experimental work has gradually improved our knowledge of the fracture process in snow. However, our limited understanding of crack propagation and fracture arrest propensity prevents the evaluation of avalanche release sizes and thus impedes hazard assessment. To address this issue, slab tensile failure propensity is examined using a mechanically-based statistical model of the slab-WL system based on the finite element method. This model accounts for WL heterogeneity, stress redistribution by elasticity of the slab and the slab possible tensile failure. Two types of avalanche release are distinguished in the simulations: (1) full-slope release if the heterogeneity is not sufficient to stop crack propagation and to trigger a tensile failure within the slab, (2) partial-slope release if fracture arrest and slab tensile failure occurs due to the WL heterogeneity. The probability of these two release types is presented as a function of the characteristics of WL heterogeneity and of the slab. One of the main outcomes is that, for realistic values of the parameters, the tensile failure propensity is mainly influenced by slab properties. Hard and thick snow slabs are more prone to wide-scale crack propagation and thus lead to larger avalanches (full-slope release). In this case, the avalanche size is mainly influenced by topographical and morphological features such as rocks, trees, slope curvature and the spatial variability of the snow depth as it is often claimed in the literature.

Gaume, J.; Chambon, G.; Eckert, N.; Naaim, M.; Schweizer, J.

2014-12-01

345

Strength and flexibility properties of advanced ceramic fabrics  

NASA Technical Reports Server (NTRS)

The mechanical properties of four advanced ceramic fabrics are measured at a temperature range of 23 C to 1200 C. The fabrics evaluated are silica, high-and low-boria content aluminoborosilicate, and silicon carbide. Properties studied include fabric break strengths from room temperature to 1200 C, and bending durability after temperature conditioning at 1200 C and 1400 C. The interaction of the fabric and ceramic insulation is also studied for shrinkage, appearance, bend resistance, and fabric-to-insulation bonding. Based on these tests, the low-boria content aluminoborosilicate fabric retains more strength and fabric durability than the other fabrics studied at high temperature.

Sawko, P. M.; Tran, H. K.

1985-01-01

346

Tensile properties of a 2014 aluminum alloy in the temperature range 250° to 500 °C  

Microsoft Academic Search

The effect of deformation temperature in the range 250 to 500 C on the tensile ductility of a 2014 aluminum alloy was measured\\u000a in constant extension-rate tensile tests, generally with an initial strain rate of 2.6 X 10-3 s-1. Elongation at fracture increased with increasing temperature in the range 250 to 450 C, reaching a maximum value of ~180\\u000a pct,

G. L’Esperance; M. H. Loretto; W. T. Roberts; D. Price; D. V. Wilson

1984-01-01

347

Tensile properties of a 2014 aluminum alloy in the temperature range 250° to 500 °C  

Microsoft Academic Search

The effect of deformation temperature in the range 250° to 500 °C on the tensile ductility of a 2014 aluminum alloy was measured in constant extension-rate tensile tests, generally with an initial strain rate of 2.6 X 10-3 s-1. Elongation at fracture increased with increasing temperature in the range 250° to 450 °C, reaching a maximum value of ~180 pct,

G. L'Esperance; M. H. Loretto; W. T. Roberts; D. Price; D. V. Wilson

1984-01-01

348

Effect of excitation energy on dentine bond strength and composite properties.  

PubMed

A number of available dentine adhesives and dental composites require light activation for polymerization. There are many variables which affect the light absorbing properties (e.g. bond strength) of these materials. The purpose of this study was to determine the influence of excitation energy (EE) on the dentine shear bond strength (SBS) of two lengths (2.1 mm and 3.25 mm) of light-cured (or dual-cured) dentine adhesives/dental composites. Diametral tensile (DTS) and compressive (CS) strengths of the same composites were also studied as a function of EE. Three resin composites with their respective adhesives (Marathon One/Tenure, Z100/Scotchbond Multi-Purpose and Herculite XRV/Optibond) were used. Five commercial curing lights were used to produce spectra of 100-650 mW cm-2. The data were analysed using ANOVA and the Tukey LSD test. No significant correlation was observed at the P > 0.05 level between EE and SBS in the shorter specimens. The SBS of Optibond is independent of EE and composite length. The SBS data were also analysed with Weibull statistics. The characteristic strengths calculated varied between 14 and 27 MPa. For the composites tested, mean values of DTS varied between 33 and 54 MPa and CS varied between 167 and 414 MPa. The DTS and CS of Z100 were significantly greater than those of the other materials. Intensities > or = 250 mW cm-2 produced equivalent mechanical properties within all composite materials and equivalent bond strengths in systems which included dentine, adhesive and composite resin. PMID:8027461

Lee, S Y; Greener, E H

1994-06-01

349

Effect of Friction Stir Processing on Microstructure and Tensile Properties of an Investment Cast Al-7Si-0.6Mg Alloy  

SciTech Connect

Friction stir processing (FSP) is emerging as a promising tool for microstructural modification. The present study assesses the effects of FSP on the microstructure and mechanical properties of an investment cast Al-7Si-Mg alloy. FSP eliminates porosity and significantly refines eutectic Si particles. The extent of particle refinement varied with changes in processing conditions. High tool rotation rate and low to intermediate tool traverse speed generated a higher volume fraction of finer particles. Tensile ductility changed significantly as a result of FSP, whereas UTS improved only marginally. Yield strength was similar in both cast and FSPed samples under various heat treated conditions, with the highest value obtained after a T6 heat treatment. Further, FSP caused significant grain refinement in the stir zone, subsequently transforming into very coarse grains as abnormal grain growth (AGG) occurred during solution treatment at high temperature.

Jana, Saumyadeep; Mishra, Rajiv S.; Baumann, John B.; Grant, Glenn J.

2010-10-01

350

Irradiation and thermal effects on the tensile properties of Inconel alloy 718. [Wrought and weld-deposited  

Microsoft Academic Search

The effects of neutron irradiation and out-of-flux aging on the tensile properties of wrought and weld-deposited Inconel 718 were investigated following fast-reactor (EBR-II) irradiation to total fluences ranging from 0.55 x 10²² cm² (approximately 400°C) to 6.6 x 10²² n\\/cm² (649°C) and thermal exposure at 538°C and 649°C for durations to 10,000 hours. Classical irradiation hardening is exhibited by this

A. L. Ward; J. M. Steichen; R. L. Knecht

1976-01-01

351

Effect of minor Sc additions on structure, age hardening and tensile properties of aluminium alloy AA8090 plate  

Microsoft Academic Search

The grain structure, age hardening response, precipitate structure and tensile properties of AA8090 alloy plate without and with minor additions of Sc were investigated. Primary aluminide particles were present in all alloys. Sc additions ?0.43% resulted in refinement of the as-cast grain structure. Further investigations on 0.11% and 0.22% Sc containing alloys showed that the subgrain size was finer while

Vijaya Singh; K. Satya Prasad; Amol A. Gokhale

2004-01-01

352

Influence of Aging Parameters on the Tensile Properties and Quality Index of Al-9 Pct Si-1.8 Pct Cu-0.5 Pct Mg 354-Type Casting Alloys  

NASA Astrophysics Data System (ADS)

The current study was carried out with a view to investigating the influence of age-hardening parameters, aging temperature and time, on the tensile properties and quality indices of a high-strength Al-9 pct Si casting alloy, namely, 354-Al-9 pct Si-1.8 pct Cu-0.5 pct Mg. Quality charts were used as an evaluation tool for selecting the optimum conditions to be applied, in practice, in order to develop high strength and optimum quality in 354 casting alloy. Aging at a low temperature of 428 K (155 °C) was observed to produce the greatest strength and optimum quality in the 354-type castings compared to aging at higher temperatures. The peak strength observed for 354 alloy may be attained after shorter aging times on the condition that the aging temperature is increased. The aging times required for reaching peak strength in 354 alloys are 72 hours, 40 hours, 8 hours, 1 hour, and 15 minutes at aging temperatures of 428 K, 443 K, 468 K, 493 K, and 518 K (155 °C, 170 °C, 195 °C, 220 °C, and 245 °C), respectively. Aging treatment at higher temperatures is accompanied by a reduction in the tensile properties and quality index values of the castings; however, it also introduces the possibility of a significant economical strategy for minimizing the time and the cost of this same treatment. Aging treatment at a lower temperature of 428 K (155 °C) produces fine and dense precipitates displaying smaller interparticle spacing, while at higher aging temperatures, such as 518 K (245 °C), the precipitates are coarser in size, less dense, and more widely dispersed. The quality charts developed in the course of the current research facilitate the interpretation and evaluation of the tensile properties of the 354 alloy. Such charts provide a logical evaluation tool, from the metallurgical point of view, for an accurate prediction of the influence of aging parameters studied on the properties of the alloys. Depending on the required level of tensile properties and based on the quality charts developed, it is possible to make a rigorous selection as to the most suitable aging parameters to be applied to the 354 alloy so as to obtain the best possible cost-effective compromise between alloy strength and quality.

Ammar, H. R.; Samuel, A. M.; Samuel, F. H.; Simielli, E.; Sigworth, G. K.; Lin, J. C.

2012-01-01

353

Effects of Heat Treatment on Microstructure and Tensile Properties of a Fe-27Mn-12Al-0.8C Low-Density Steel  

NASA Astrophysics Data System (ADS)

A low-density duplex steel of Fe-27Mn-12Al-0.8C (density 6.53 g/cm3) was directly quenched to room temperature and ordering treated at 500°C and 700°C after solution treatment. The heat-treated microstructures and corresponding room-temperature tensile properties were investigated. The ? phase precipitated in austenite in all the cases such that its size became coarser with increasing ordering temperature. Ferrite of the as-quenched steel consisted of the B2 domains and disordered ferrite with uniformly distributed nanosized D03 particles. Ferrite of the 700°C ordering steel exhibited basically identical features to the as-quenched steel, but with the coarser B2 domains, finer D03 particles, and less disordered ferrite. By contrast, the D03 domains were mainly observed in ferrite of the 500°C ordering steel. The yield strength of the 500°C ordering steel was higher than other two steels, which showed the similar yield strengths. The elongation of the as-quenched steel was higher than two ordering-treated steels. Deformation of austenite was manifested by the ? phase shearing by planar gliding dislocations. Intensive interactions of superdislocations were mainly observed in ferrite, depending on the type of the ordered phase. Factors influencing the strength and deformation behavior of the low-density duplex steel were discussed based on observation of deformed microstructure. Overall, the high-Mn/Al duplex steels with the ordered phases exhibit the high specific strength, the low density, and the moderate strain hardening that are suitable for the structural use requiring high strength and light weight.

Park, Kyung-Tae; Hwang, Si Woo; Son, Chang Young; Lee, Jae-Kon

2014-09-01

354

Tensile Properties of 17-7 PH and 12 MoV Stainless-Steel Sheet under Rapid-Heating and Constant-Temperature Conditions  

NASA Technical Reports Server (NTRS)

Results are presented of rapid-heating tests of 17-7 PH and 12 MoV stainless-steel sheet heated to failure at temperature rates from about 1 F to 170 F per second under constant-load conditions. Yield and rupture strengths obtained from rapid-heating tests are compared with yield and tensile strengths obtained from short-time elevated-temperature tensile tests (30-minute exposure). A rate-temperature parameter was used to construct master curves from which yield and rupture stresses or temperatures can be predicted. A method for measuring strain by optical means is described.

Manning, Charles R., Jr.; Price, Howard L.

1961-01-01

355

Oxidation resistance in LBE and air and tensile properties of ODS ferritic steels containing Al/Zr elements  

NASA Astrophysics Data System (ADS)

The effects of Al and Zr addition on improvement of oxidation resistance in lead-bismuth eutectic (LBE) and in air as well as the tensile properties were investigated for the oxide dispersion strengthened (ODS) steels. The 16Cr-4Al-0.8Zr-ODS steel samples were fabricated by a sol-gel method combining with spark plasma sintering technique. The tests in LBE at 600 °C for 1000 h indicate the good oxidation resistance comparing with the specimens without Zr/Al elements. The samples also exhibit superior oxidation resistance in air due to formation of dense and continuous aluminum oxide film. Minor Zr addition prevents the Al element induced coarsening of the oxide particles in ODS steels and significantly improves the ultimate tensile stress and total elongation of the samples.

Gao, R.; Xia, L. L.; Zhang, T.; Wang, X. P.; Fang, Q. F.; Liu, C. S.

2014-12-01

356

Simultaneous determination of the impurity and radial tensile strength of reduced glutathione tablets by a high selective NIR-PLS method  

NASA Astrophysics Data System (ADS)

This paper establishes a high-throughput and high selective method to determine the impurity named oxidized glutathione (GSSG) and radial tensile strength (RTS) of reduced glutathione (GSH) tablets based on near infrared (NIR) spectroscopy and partial least squares (PLS). In order to build and evaluate the calibration models, the NIR diffuse reflectance spectra (DRS) and transmittance spectra (TS) for 330 GSH tablets were accurately measured by using the optimized parameter values. For analyzing GSSG or RTS of GSH tablets, the NIR-DRS or NIR-TS were selected, subdivided reasonably into calibration and prediction sets, and processed appropriately with chemometric techniques. After selecting spectral sub-ranges and neglecting spectrum outliers, the PLS calibration models were built and the factor numbers were optimized. Then, the PLS models were evaluated by the root mean square errors of calibration (RMSEC), cross-validation (RMSECV) and prediction (RMSEP), and by the correlation coefficients of calibration (Rc) and prediction (Rp). The results indicate that the proposed models have good performances. It is thus clear that the NIR-PLS can simultaneously, selectively, nondestructively and rapidly analyze the GSSG and RTS of GSH tablets, although the contents of GSSG impurity were quite low while those of GSH active pharmaceutical ingredient (API) quite high. This strategy can be an important complement to the common NIR methods used in the on-line analysis of API in pharmaceutical preparations. And this work expands the NIR applications in the high-throughput and extraordinarily selective analysis.

Li, Juan; Jiang, Yue; Fan, Qi; Chen, Yang; Wu, Ruanqi

357

The dynamic properties behavior of high strength concrete under different strain rate  

NASA Astrophysics Data System (ADS)

This paper present a number experimental data and numerical technique used in the dynamic behavior of high strength concrete. A testing device is presented for the experimental study of dynamic behavior material under high strain rates. The specimen is loaded by means of a high carbon steel Hopkinson pressure bar (40 mm diameter, 3000 mm long input bar and 1500 mm long out put bar) allowing for the testing of specimen diameter is large enough in relation to the size of aggregates. The other method also proposed for measuring tensile strength, the measurement method based on the superposition and concentration of tensile stress wave reflected both from the free-free ends of striking bar and the specimen bar. The compression Hopkinson bar test, the impact tensile test of high strength concrete bars are performed, together with compression static strength test. In addition, the relation between break position under finite element simulation and impact tensile strength are examined. The three-dimensional simulation of the specimen under transient loading are presented and comparisons between the experimental and numerical simulation on strain rate effects of constitutive law use in experimental are study.

Abdullah, Hasballah; Husin, Saiful; Umar, Hamdani; Rizal, Samsul

2005-04-01

358

Study on strength, elastic modulus of artifical lightweight aggregate concrete  

NASA Astrophysics Data System (ADS)

Aggregate strength of artificial lightweight concrete and concrete used with this artificial lightweight aggregate can be expected to have nearly the same strength as normal weight concrete. An experimental study of properties of concrete strength and correlation between compressive and tensile and flexural strengths and elastic modulus of its concrete was made.

Kakizaki, M.

1982-04-01

359

Controlling factors in tensile deformation of nanocrystalline cobalt and nickel  

NASA Astrophysics Data System (ADS)

In an effort to understand and enhance the tensile ductility of truly nanocrystalline metals, we have investigated and compared the mechanical behavior, especially the tensile behavior, of hexagonal close-packed (hcp) nanocrystalline cobalt (˜20 nm) and face-centered cubic (fcc) nanocrystalline nickel (˜28 nm). Although both materials exhibit obvious plasticity in tension, their uniform tensile ductility, tensile elongation-to-failure, and fracture behavior are drastically different. In-situ synchrotron x-ray diffraction and ultra-small angle x-ray scattering reveal distinct deformation disparity in terms of residual strain development, texture evolution, nanovoid formation, and subsequent strain-hardening and strain-rate-hardening behavior. The dependence of tensile property on the strain rate and temperature is examined and discussed. Factors that influence the strength and ductility of nanocrystalline metals are considered and prioritized according to the current findings. A new Hall-petch relationship is proposed for nanocrystalline nickel.

Wang, Y. M.; Ott, R. T.; van Buuren, T.; Willey, T. M.; Biener, M. M.; Hamza, A. V.

2012-01-01

360

Antimicrobial properties and dentin bonding strength of magnesium phosphate cements.  

PubMed

The main objective of this work was to assess the antimicrobial properties and the dentin-bonding strength of novel magnesium phosphate cements (MPC). Three formulations of MPC, consisting of magnesium oxide and a phosphate salt, NH4H2PO4, NaH2PO4 or a mixture of both, were evaluated. As a result of the setting reaction, MPC transformed into either struvite (MgNH4PO4·6H2O) when NH4H2PO4 was used or an amorphous magnesium sodium phosphate when NaH2PO4 was used. The MPC had appropriate setting times for hard tissue applications, high early compressive strengths and higher strength of bonding to dentin than commercial mineral trioxide aggregate cement. Bacteriological studies were performed with fresh and aged cements against three bacterial strains, Escherichia coli, Pseudomonas aeruginosa (planktonic and in biofilm) and Aggregatibacter actinomycetemcomitans. These bacteria have been associated with infected implants, as well as other frequent hard tissue related infections. Extracts of different compositions of MPC had bactericidal or bacteriostatic properties against the three bacterial strains tested. This was associated mainly with a synergistic effect between the high osmolarity and alkaline pH of the MPC. These intrinsic antimicrobial properties make MPC preferential candidates for applications in dentistry, such as root fillers, pulp capping agents and cavity liners. PMID:23747324

Mestres, G; Abdolhosseini, M; Bowles, W; Huang, S-H; Aparicio, C; Gorr, S-U; Ginebra, M-P

2013-09-01

361

Variation in Mechanical Properties and Heterogeneity in Microstructure of High-Strength Ferritic Steel During Mill Trial  

NASA Astrophysics Data System (ADS)

HS600 and HS800 are two new generation, high-strength advanced ferritic steels that find widespread application in automobiles. During commercial production of the same grades with different thicknesses, it has been found that mechanical properties like tensile strength and stretchability varied widely and became inconsistent. In the current endeavor, two different thicknesses have been chosen from a mill trial sample of HS600 and HS800. An in-depth structural characterization was carried out for all four alloys to explain the variation in their respective mechanical and shear punch properties. The carbon content was smaller and Ti + Mo quantity was higher in case of HS800 with respect to HS600. The microstructure of both steels consisted of the dispersion of (Ti,Mo)C in a ferrite matrix. The grain size of HS800 was little larger than HS600 due to an increased coiling temperature (CT) of the former in comparison to the latter. It was found that in case of same grade of steel with a different thickness, a variation in microstructure occurred due to change in strain, CT, and cooling rate. The strength and stretch formability of these two alloys were predominantly governed by a microalloyed carbide. In this respect, carbides with a size range above 5 nm were responsible for loosing coherency with ferrite matrix. In case of HS600, both ?5 and >5-nm size (Ti,Mo)C precipitates shared a nearly equal fraction of microalloyed precipitates. However, for HS800, >5-nm size (Ti,Mo)C carbide was substantially higher than ?5-nm size alloy carbides. The ultimate tensile strength and yield strength of HS800 was superior to that of HS600 owing to a higher quantity of microalloyed carbide with a decreased column width and interparticle distance. A higher degree of in-coherency of HS800 made the alloy prone to crack formation with low stretchability.

Ghosh, M.; Barat, K.; Das, S. K.; Ravi Kumar, B.; Pramanick, A. K.; Chakraborty, J.; Das, G.; Hadas, S.; Bharathy, S.; Ray, S. K.

2014-06-01

362

Effect of temperature and aging on the mechanical properties of concrete  

Microsoft Academic Search

In Part I, empirical relationships between compressive strength and splitting tensile strength or elastic modulus with temperature and aging were proposed. This paper investigates new prediction models estimating splitting tensile strength and elastic modulus without knowing compressive strength. The prediction model is suggested on the basis of the equation that was suggested to predict compressive strength. The mechanical properties calculated

Jin-Keun Kim; Sang Hun Han; Seok Kyun Park

2002-01-01

363

Swelling and tensile properties of EBR-II-irradiated tantalum alloys for space reactor applications  

Microsoft Academic Search

The tantalum alloys T-111, ASTAR-811C, Ta-10 W, and unalloyed tantalum were examined following EBR-II irradiation to a fluence of 1.7 x 10²⁶ neutrons\\/m² (E > 0.1 MeV) at temperatures from 650 to 950 K. Swelling was found to be negligible for all alloys; only tantalum was found to exhibit swelling, 0.36%. Tensile testing revealed that irradiated T-111 and Ta-10 W

M. L. Grossbeck; F. W. Wiffen

1985-01-01

364

CHARACTERIZATION OF MONOLITHIC FUEL FOIL PROPERTIES AND BOND STRENGTH  

SciTech Connect

Understanding fuel foil mechanical properties, and fuel / cladding bond quality and strength in monolithic plates is an important area of investigation and quantification. Specifically, what constitutes an acceptable monolithic fuel – cladding bond, how are the properties of the bond measured and determined, and what is the impact of fabrication process or change in parameters on the level of bonding? Currently, non-bond areas are quantified employing ultrasonic determinations that are challenging to interpret and understand in terms of irradiation impact. Thus, determining mechanical properties of the fuel foil and what constitutes fuel / cladding non-bonds is essential to successful qualification of monolithic fuel plates. Capabilities and tests related to determination of these properties have been implemented at the INL and are discussed, along with preliminary results.

D E Burkes; D D Keiser; D M Wachs; J S Larson; M D Chapple

2007-03-01

365

Improvement in Mechanical Properties of A356 Tensile Test Bars Cast in a Permanent Mold by Application of a Knife Ingate  

NASA Astrophysics Data System (ADS)

As a standard test-bar permanent mold, the "Stahl" Mold has been widely used in foundries to assess the properties of cast alloys. However, inferior mechanical properties are often obtained with this mold due to shrinkage-induced microporosity in the gage section. In order to improve the mechanical properties, a design modification comprising a thin knife ingate between the feeder and test-bar cavity was evaluated in this work. The new design was studied by computer-aided simulation. Simulations predicted that the knife ingate improved the metal feeding capability and reduced the shrinkage microporosity at the gage section from 3 to 1 pct. Experimental verification work has been undertaken with aluminum alloy A356, and the results were analyzed by a statistics theory-based factorial analysis method. The new design resulted in main effects with ultimate tensile strength (UTS) improvement of 20 MPa (relative 12 pct) and elongation increment of 2 pct (relative 45 pct) for the as-cast test bars.

Wang, Yaou; Schwam, David; Neff, David V.; Chen, Chai-Jung; Zhu, Xuejun

2012-03-01

366

Effect of open hole on tensile failure properties of 2D triaxial braided textile composites and tape equivalents  

NASA Technical Reports Server (NTRS)

The unnotched and notched (open hole) tensile strength and failure mechanisms of two-dimensional (2D) triaxial braided composites were examined. The effect of notch size and notch position were investigated. Damage initiation and propagation in notched and unnotched coupons were also examined. Theory developed to predict the normal stress distribution near an open hole and failure for tape laminated composites was evaluated for its applicability to triaxial braided textile composite materials. Four fiber architectures were considered with different combinations of braid angle, longitudinal and braider yam size, and percentage of longitudinal yarns. Tape laminates equivalent to textile composites were also constructed for comparison. Unnotched tape equivalents were stronger than braided textiles but exhibited greater notch sensitivity. Notched textiles and tape equivalents have roughly the same strength at large notch sizes. Two common damage mechanisms were found: braider yams cracking and near notch longitudinal yarn splitting. Cracking was found to initiate in braider yarns in unnotched and notched coupons, and propagate in the direction of the braider yarns until failure. Longitudinal yarn splitting occurred in three of four architectures that were longitudinally fiber dominated. Damage initiation stress decreased with increasing braid angle. No significant differences in prediction of near notch stress between measured and predicted stress were weak for textiles with large braid angle. Notch strength could not be predicted using existing anisotropic theory for braided textiles due to their insensitivity to notch.

Norman, Timothy L.; Anglin, Colin; Gaskin, David; Patrick, Mike

1995-01-01

367

Effects of Long Term Thermal Exposure on Chemically Pure (CP) Titanium Grade 2 Room Temperature Tensile Properties and Microstructure  

NASA Technical Reports Server (NTRS)

Room temperature tensile testing of Chemically Pure (CP) Titanium Grade 2 was conducted for as-received commercially produced sheet and following thermal exposure at 550 and 650 K for times up to 5,000 h. No significant changes in microstructure or failure mechanism were observed. A statistical analysis of the data was performed. Small statistical differences were found, but all properties were well above minimum values for CP Ti Grade 2 as defined by ASTM standards and likely would fall within normal variation of the material.

Ellis, David L.

2007-01-01

368

Effect of nitrogen on tensile properties and structures of T-111 (tantalum, 8 percent tungsten, 2 percent hafnium) tubing  

NASA Technical Reports Server (NTRS)

The effect of controlled nitrogen additions was evaluated on the mechanical properties of T-111 (Ta-8W-2Hf) fuel pin cladding material proposed for use in a lithium-cooled nuclear reactor concept. Additions of 80 to 1125 ppm nitrogen resulted in increased strengthening of T-111 tubular section test specimens at temperatures of 25 to 1200 C. Homogeneous distributions of up to 500 ppm nitrogen did not seriously decrease tensile ductility. Both single and two-phase microstructures, with hafnium nitride as the second phase, were evaluated in this study.

Buzzard, R. J.; Metroka, R. R.

1973-01-01

369

Axisymmetric Flow Properties for Magnetic Elements of Differing Strength  

NASA Technical Reports Server (NTRS)

Aspects of the structure and dynamics of the flows in the Sun's surface shear layer remain uncertain and yet are critically important for understanding the observed magnetic behavior. In our previous studies of the axisymmetric transport of magnetic elements we found systematic changes in both the differential rotation and the meridional flow over the course of Solar Cycle 23. Here we examine how those flows depend upon the strength (and presumably anchoring depth) of the magnetic elements. Line of sight magnetograms obtained by the HMI instrument aboard SDO over the course of Carrington Rotation 2097 were mapped to heliographic coordinates and averaged over 12 minutes to remove the 5-min oscillations. Data masks were constructed based on the field strength of each mapped pixel to isolate magnetic elements of differing field strength. We used Local Correlation Tracking of the unmasked data (separated in time by 1- to 8-hours) to determine the longitudinal and latitudinal motions of the magnetic elements. We then calculated average flow velocities as functions of latitude and longitude from the central meridian for approx 600 image pairs over the 27-day rotation. Variations with longitude indicate and characterize systematic errors in the flow measurements associated with changes in the signal from disk center to limb. Removing these systematic errors reveals changes in the axisymmetric flow properties that reflect changes in flow properties with depth in the surface shear layer.

Rightmire-Upton, Lisa; Hathaway, David H.

2012-01-01

370

ER-? agonist induces conversion of fibroblasts into myofibroblasts, while ER-? agonist increases ECM production and wound tensile strength of healing skin wounds in ovariectomised rats.  

PubMed

Oestrogen deprivation is one of the major factors responsible for many age-related processes, including poor wound healing in women. Previously, it has been shown that oestrogens have a modulatory effect in different wound-healing models. Therefore, in this study, the effect of selective oestrogen receptor (ER) agonists (PPT - ER-? agonist, DPN - ER-? agonist) on excisional and incisional wound-healing models was compared in ovariectomised rats in vivo as well as on human dermal fibroblasts (HDF) and human umbilical endothelial cells (HUVEC) in vitro. In the in vivo study, 4 months after either ovariectomy or sham ovariectomy, Sprague-Dawley rats were randomly divided into four groups and subjected to two incisional and excisional wounds: (i) control - sham operated, vehicle-treated; (ii) ovariectomised, vehicle-treated; (iii) ovariectomised, PPT treated; (iv) ovariectomised, DPN treated. In the in vitro study, HDFs and HUVECs were used. After treatment with ER agonists, cells were processed for immunocytochemistry and gelatin zymography. Our study shows that stimulation of ER-? leads to the differentiation of fibroblasts into myofibroblasts both in vivo and in vitro. On the other hand, the formation of extracellular matrix was more prominent, and wound tensile strength (TS) was increased when ER-? was stimulated. In contrast, stimulation of ER-? led to a more prominent increase in the expression of MMP-2 and decrease in wound TS. New information is presented in this investigation concerning oestrogen replacement therapy (ERT) in different wound-healing models. This study demonstrates that the ERT should be both wound and receptor-type specific. PMID:21507066

Novotný, Martin; Vasilenko, Tomáš; Varinská, Lenka; Smetana, Karel; Szabo, Pavol; Sarišský, Marek; Dvo?ánková, Barbora; Mojžiš, Ján; Bobrov, Nikita; Toporcerová, Silvia; Sabol, Franitšek; Matthews, Bryan J O; Gál, Peter

2011-09-01

371

Electro-mechanical Properties of Carbon Nanotubes: Effect of Small Tensile and Torsional Strains  

NASA Technical Reports Server (NTRS)

We present a simple picture to calculate the bandgap ($E_g$) of carbon nanotubes (CNT) in the presence of uniform torsional and tensile strain ($\\sigma$). We find that under tensile strain, $ absolute value of dE_g/d\\sigma$ of zig-zag tubes is approximately equal to $3t_0$, where $t_0$ is the hopping parameter. Further, $ absolute value of dE_g/d\\sigma$ decreases as the chirality changes to armchair, where it takes the value zero. The sign of $dE_g/d\\sigma$ follows the $(N_x-N_y) *mod 3$(equal to - 1, 0 and +1) rule. In contrast to the above, we show that under torsional strain, $absolute value of dE_g/d\\sigma$ of armchair tubes is approximately equal to $3t_0$ and continually decreases as the chirality changes to zig-zag, where is takes a small value. The sign of $dE_g/d\\sigma$ again follows the $(N_x-N_y)*mod 3$ rule. Finally, we predict a change in the sign of $dE_g/d\\sigma$ as function of strain, corresponding to a change in the value of $q$ that corresponds to the bandgap minimum.

Anantram, M. P.; Yang, Liu; Han, Jie; Liu, J. P.; Saini, Subhash (Technical Monitor)

1999-01-01

372

The effect of Mg addition on microstructure and tensile and stress rupture properties of a P/M Al-Fe-Ce alloy  

SciTech Connect

Dispersion strengthened Aluminium alloys based on Al-TM (TM = transition metal) type systems are being developed for elevated temperature structural applications in aerospace at temperatures up to 623K as possible substitutes for the more expensive and refractory Ti alloys currently used. Alloy systems containing transition metals such as Fe, Ni, V, Cr, Zr, Mo and Ti with possible additions of Si and Ce (or misch metal) have been investigated. Al-Fe-Ce alloys belong to this class of dispersion strengthened aluminium alloys which are strengthened primarily by ternary Al-Fe-Ce precipitates. The matrix in this case is almost pure aluminium. Further strengthening of the alloy may therefore be possible by addition of elements such as Mg which impart solid solution strengthening. This should also result in enhancement in elevated temperature strength and stress rupture properties. It is reported that the addition of Mg to Al-Fe-Mm (Mm = misch metal) alloy does not result in formation of new phases in melt spun ribbons even after annealing at 773K thereby confirming that Mg is retained in solid solution. The aim of the present work is to investigate the effect of Mg addition on the microstructure and tensile and stress rupture properties of an Al-Fe-Ce alloy.

Prakash, U.; Raghu, T.; Kamat, S.V.; Gokhale, A.A. [Defence Metallurgical Research Lab., Hyderabad (India)] [Defence Metallurgical Research Lab., Hyderabad (India)

1998-09-04

373

Direct Lentiviral-Cyclooxygenase 2 Application to the Tendon-Bone Interface Promotes Osteointegration and Enhances Return of the Pull-Out Tensile Strength of the Tendon Graft in a Rat Model of Biceps Tenodesis  

PubMed Central

This study sought to determine if direct application of the lentiviral (LV)-cyclooxygenase 2 (COX2) vector to the tendon-bone interface would promote osteointegration of the tendon graft in a rat model of biceps tenodesis. The LV-COX2 gene transfer strategy was chosen for investigation because a similar COX2 gene transfer strategy promoted bony bridging of the fracture gap during bone repair, which involves similar histologic transitions that occur in osteointegration. Briefly, a 1.14-mm diameter tunnel was drilled in the mid-groove of the humerus of adult Fischer 344 rats. The LV-COX2 or ?gal control vector was applied directly into the bone tunnel and onto the end of the tendon graft, which was then pulled into the bone tunnel. A poly-L-lactide pin was press-fitted into the tunnel as interference fixation. Animals were sacrificed at 3, 5, or 8 weeks for histology analysis of osteointegration. The LV-COX2 gene transfer strategy enhanced neo-chondrogenesis at the tendon-bone interface but with only marginal effect on de novo bone formation. The tendon-bone interface of the LV-COX2-treated tenodesis showed the well-defined tendon-to-fibrocartilage-to-bone histologic transitions that are indicative of osteointegration of the tendon graft. The LV-COX2 in vivo gene transfer strategy also significantly enhanced angiogenesis at the tendon-bone interface. To determine if the increased osteointegration was translated into an improved pull-out mechanical strength property, the pull-out tensile strength of the LV-COX2-treated tendon grafts was determined with a pull-out mechanical testing assay. The LV-COX2 strategy yielded a significant improvement in the return of the pull-out strength of the tendon graft after 8 weeks. In conclusion, the COX2-based in vivo gene transfer strategy enhanced angiogenesis, osteointegration and improved return of the pull-out strength of the tendon graft. Thus, this strategy has great potential to be developed into an effective therapy to promote tendon-to-bone healing after tenodesis or related surgeries. PMID:24848992

Wergedal, Jon E.; Stiffel, Virginia; Lau, Kin-Hing William

2014-01-01

374

Approaches for Tensile Testing of Braided Composites  

NASA Technical Reports Server (NTRS)

For angleply composites, lamina tension and compression strengths are commonly determined by applying classical lamination theory to test data obtained from testing of angleply composite specimens. For textile composites such as 2D triaxial braids, analysis is more complex and standard test methods do not always yield reliable strength measurements. This paper describes recent research focused on development of more reliable tensile test methods for braided composites and presents preliminary data for various approaches. The materials investigated in this work have 0deg+/-60 2D triaxial braid architecture with nearly equal fiber volume fraction in each of the three fiber directions. Flat composite panels are fabricated by resin transfer molding (RTM) using six layers of the braided preform aligned along the 0deg fiber direction. Various epoxy resins are used as matrix materials. Single layer panels are also fabricated in order to examine local variations in deformation related to the braid architecture. Specimens are cut from these panels in the shape of standard straight-sided coupons, an alternative bowtie geometry, and an alternative notched geometry. Axial tensile properties are measured using specimens loaded along the 0deg fiber direction. Transverse tensile properties are measured using specimens loaded perpendicular to the 0deg fibers. Composite tubes are also fabricated by RTM. These tubes are tested by internal pressurization using a soft rubbery material sealed between the inside diameter of the tube and the load fixtures. The ends of the tube are unconstrained, so the primary load is in the hoop direction. Tubes are fabricated with the 0deg fibers aligned along the tube axis by overbraiding the preform on a mandrel. Since the loading is in the hoop direction, testing of the overbraided tube provides a measure of transverse tensile strength. Previous work has indicated that straight-sided coupons yield a transverse tensile strength that is much lower than the expected material strength because of premature edge-initiated failure. Full-field strain measured during transverse tensile tests clearly showed accumulation of edge damage prior to failure. In the current work, high speed video and testing of single layer specimens are used to investigate potential failure mechanisms in more detail. High speed video clearly shows the edge initiation in six layer transverse tensile test coupons. Specimens with the bowtie geometry and the notched geometry minimize this edge effect and yield significantly higher transverse tensile strength values compared to the straight-sided coupons. However, bowtie and notched specimens geometries are not ideal because of the non-uniform stress and strain fields in the region of failure. Testing of tubes using internal pressurization eliminates edge-initiated failure and provides a more uniform state of stress and strain. Preliminary results indicate that bowtie, notched, and tube specimens yield comparable values for transverse tensile strength and that these values are much higher than the strength measured using a straight-sided coupon.

Roberts, Gary D.; Salem, Jonathan A.; Bail, Justin L.; Kohlman, Lee W.; Binienda, Wieslaw K.; Martin, Richard E.

2011-01-01

375

Optimizing the tensile properties of polyvinyl alcohol hydrogel for the construction of a bioprosthetic heart valve stent.  

PubMed

Although bioprosthetic heart valves offer the benefits of a natural opening and closing, better hemodynamics, and avoidance of life-long anticoagulant therapy, they nevertheless tend to fail in 10-15 years from tears and calcification. Several authors, including the present ones, have identified the rigid stent as a factor contributing to these failures. The ultimate solution is an artificial heart valve that has mechanical properties that allow it to move in conformity with the aortic root during the cardiac cycle, has superior hemodynamics, is nonthrombogenic, will last more than 20 years, and mitigates the need for anticoagulants. We have identified a polymer, polyvinyl alcohol (PVA) hydrogel, that has mechanical properties similar to soft tissue. The purpose of this research is to match the tensile properties of PVA to the porcine aortic root and to fabricate a stent prototype for a bioprosthetic heart valve with the use of the PVA hydrogel. Specimens of 15% w/w PVA were prepared by processing through 1-6 cycles of freezing (-20 degrees C) at 0.2 degrees C/min freeze rate and thawing (+20 degrees C) at different thawing rates (0.2 degrees C/min and 1 degrees C/min), for different holding times (1 and 6 h) at -20 degrees C. Subsequently tensile tests and stress-relaxation tests were conducted on the specimens. The different holding times at -20 degrees C demonstrated no difference in the result. The slower thawing rate improved the tensile properties but did not produce significant changes on the stress-relaxation properties. The nonlinear stress-strain curve for the PVA after the fourth freeze-thaw cycle matched the porcine aortic root within the physiological pressure range. The stress-relaxation curve for PVA also approximated the shape of the aortic root. The complex geometry of an artificial heart valve stent was successfully injection molded. These results, in combination with other preliminary findings for biocompatibility and fatigue behavior, suggest that PVA hydrogel is a promising biomaterial for implants, catheters, and artificial skin. PMID:12418034

Wan, W K; Campbell, G; Zhang, Z F; Hui, A J; Boughner, D R

2002-01-01

376

The influence of die semiangle and of the coefficient of friction on the uniform tensile elongation of drawn copper bars  

Microsoft Academic Search

Cold drawing of bars leads to changes in the mechanical properties of the products. An increase in strength and a loss of ductility are usually observed. The tensile elongation for example, decreases as greater reductions in area in drawing are considered. Previous researche has shown that this is basically associated with a reduction in tensile uniform elongation. The present paper

H. B Campos; P. R Cetlin

1998-01-01

377

Impact of irradiation on the tensile and fatigue properties of two titanium alloys  

NASA Astrophysics Data System (ADS)

The attachment of the first wall modules of the ITER FEAT fusion reactor is designed using flexible connectors made from titanium alloys. An assessment of the tensile and fatigue performance of two candidate alloys, a classical two phase Ti6Al4V alloy and a monophase ? alloy Ti5Al2.5Sn, has been carried out using 590 MeV protons for the simulation of the fusion neutrons. The dose deposited was up to 0.3 dpa and the irradiation temperature was between 40°C and 350°C. The unirradiated tensile performances of both alloys are roughly identical. The radiation hardening is much stronger in the ?+? alloy compared with the ? alloy, and the ductility is correspondingly strongly reduced. A very fine precipitation observed by TEM in the primary and secondary ? grains of the dual phase alloy seems to be the cause of the intense radiation hardening observed. Two different regimes have been observed in the behaviour of the cyclic stresses. At a high imposed strain, the softening is small in the Ti6Al4V and larger in the Ti5Al2.5Sn. At a low imposed strain, and for both alloys, cyclic softening occurs up to about 800 cycles, but then a transition occurs, after which a regime of cyclic hardening appears. This cyclic hardening disappears after irradiation. In both materials, and for all test conditions, the compressive stress of the hysteresis loop was found to be larger than the tensile stress. The stress asymmetry seems to be triggered by the plastic deformation. The fatigue resistance of the Ti5Al2.5Sn alloy is slightly better than that of the Ti6Al4V alloy. The irradiation did not significantly affect the fatigue performance of both alloys, except for high imposed strains, where a life reduction was observed in the case of the Ti6Al4V alloy. SEM micrographs showed that the fractures were transgranular and pseudo-brittle.

Marmy, P.; Leguey, T.

2001-07-01

378

Statistical properties of microcracking in polyurethane foams under tensile test, influence of temperature and density  

E-print Network

We report tensile failure experiments on polyurethane (PU) foams. Experiments have been performed by imposing a constant strain rate. We work on heterogeneous materials for whom the failure does not occur suddenly and can develop as a multistep process through a succession of microcracks that end at pores. The acoustic energy and the waiting times between acoustic events follow power-law distributions. This remains true while the foam density is varied. However, experiments at low temperatures (PU foams more brittle) have not yielded power-laws for the waiting times. The cumulative acoustic energy has no power law divergence at the proximity of the failure point which is qualitatively in agreement with other experiments done at imposed strain. We notice a plateau in cumulative acoustic energy that seems to occur when a single crack starts to propagate.

Deschanel, Stéphanie; Vigier, Gérard; Godin, Nathalie; Ciliberto, Sergio

2006-01-01

379

Mechanical tensile testing of titanium 15-3-3-3 and Kevlar 49 at cryogenic temperatures  

NASA Astrophysics Data System (ADS)

Titanium 15-3-3-3 and Kevlar 49 are highly desired materials for structural components in cryogenic applications due to their low thermal conductivity at low temperatures. Previous tests have indicated that titanium 15-3-3-3 becomes increasingly brittle as the temperature decreases. Furthermore, little is known regarding the mechanical properties of Kevlar 49 at low temperatures, most specifically its Young's modulus. This testing investigates the mechanical properties of both materials at cryogenic temperatures through cryogenic mechanical tensile testing to failure. The elongation, ultimate tensile strength, yield strength, and break strength of both materials are provided and analyzed here.

James, B. L.; Martinez, R. M.; Shirron, P.; Tuttle, J.; Galassi, N. M.; McGuinness, D. S.; Puckett, D.; Francis, J. J.; Flom, Y.

2012-06-01

380

Shear Strength and Fatigue Properties of Human Cortical Bone Determined from Pure Shear Tests  

Microsoft Academic Search

Shear properties of bone have been inferred from torsion tests. However, torsion often causes spiral fracture planes that correspond to tensile rather than shear failure. We measured the shear properties of human cortical bone in both longitudinal and transverse directions using pure shear tests. Shearing applied transverse to the bone long axis caused fracture along a 45 plane that coincided

C. H. Turner; T. Wang; D. B. Burr

2001-01-01

381

The influences of temperature and microstructure on the tensile properties of a CoCrFeMnNi high-entropy alloy  

SciTech Connect

An equiatomic CoCrFeMnNi high-entropy alloy, which crystallizes in the face-centered cubic (FCC) crystal structure, was produced by arc melting and drop casting. The drop-cast ingots were homogenized, cold rolled, and recrystallized to obtain single-phase microstructures with three different grain sizes in the range 4~160 m. Quasi-static tensile tests were then performed at temperatures between 77 and 1073 K. Yield strength, ultimate tensile strength and ductility all increased with decreasing temperature. During the initial stages of plasticity (up to ~2% strain), deformation occurs by planar dislocation glide on the normal FCC slip system {111} 110 at all temperatures and grain sizes investigated. Undissociated 1/2 110 dislocations were observed, as were numerous stacking faults, which imply the dissociation of several of these dislocations into 1/6 112 Shockley partials. At later stages ( 20% strain), nanoscale deformation twins were observed after interrupted tests at 77 K, but not in specimens tested at room temperature where plasticity occurred exclusively by dislocations which organized into cells. Deformation twinning, by continually decreasing the mean free path of dislocations during tensile testing, produces a high degree of work hardening and a significant increase in the ultimate tensile strength. This increased work hardening prevents the early onset of necking instability and is a reason for the enhanced ductility observed at 77 K. A second way in which twinning can contribute to ductility is by providing an additional deformation mode to accommodate plasticity. However, it cannot explain the increase in yield strength with decreasing temperature in our high-entropy alloy since twinning was not observed in the early stages of plastic deformation. Since strong temperature dependencies of yield strength are also seen in binary FCC solid solution alloys, it may be an inherent solute effect, which needs further study.

Otto, Frederik [ORNL; Dlouhy, A. [Institute of Physics of Materials, Brno, Czech Republic; Somsen, Ch. [Ruhr University, Bochum, Germany; Bei, Hongbin [ORNL; Eggeler, G. [Ruhr University, Bochum, Germany; George, Easo P [ORNL

2013-01-01

382

Tensile Fracture of Ductile Materials. M.S. Thesis  

NASA Technical Reports Server (NTRS)

For brittle materials, circular voids play an important role relative to fracture, intensifing both tensile and compressive stresses. A maximum intensified tensile stress failure criterion applies quite well to brittle materials. An attempt was made to explore the possibility of extending the approach to the tensile fracture of ductile materials. The three dimensional voids that exist in reality are modelled by circular holes in sheet metal. Mathematical relationships are sought between the shape and size of the hole, after the material is plastically deformed, and the amount of deformation induced. Then, the effect of hole shape, size and orientation on the mechanical properties is considered experimentally. The presence of the voids does not affect the ultimate tensile strength of the ductile materials because plastic flow wipes out the stress intensification caused by them. However, the shape and orientation of the defect is found to play an important role in affecting the strain at fracture.

Pai, D. M.

1984-01-01

383

Effect of irradiation in a spallation neutron environment on tensile properties and microstructure of aluminum alloys 5052 and 6061  

SciTech Connect

The Accelerator Production of Tritium (APT) and the Accelerator Transmutation of Waste (ATW) programs require structural materials which retain good mechanical properties when exposed in a spallation neutron irradiation environment. One group of materials likely to withstand the environment anticipated for these systems is the aluminum alloy series. To characterize this class of materials in a prototypical irradiation environment, AL5052 (Al-2.7Mg) and Al6061 (Al-1.1Mg-0.5Si) in hardened and annealed conditions were irradiated to a fluence of 4.2 {times} 10{sup 20} neutrons/cm{sup 2} at {approximately} 100 C in a spallation neutron source. Following irradiation, tensile tests and post-test examinations were performed to determine the influence of irradiation and test temperature on mechanical properties and fracture mode. It was found that, the properties of these two aluminum alloys were not significantly affected by the irradiation exposure conditions examined here. Thus these materials may be acceptable as structural materials for APT and ATW applications. This conclusion is based on limited mechanical properties testing, supported by other information in the literature on the performance of these materials in other irradiation environments.

Dunlap, J.A.; Stubbins, J.F. [Univ. of Illinois, Urbana, IL (United States); Borden, M.J.; Sommer, W.F. [Los Alamos National Lab., NM (United States)

1996-12-31

384

Shear punch and tensile measurements of mechanical property changes induced in various austenitic alloys by high-energy mixed proton and neutron irradiation at low temperatures  

NASA Astrophysics Data System (ADS)

Tensile and shear punch tests of Inconel 718, 316L and 304L specimens irradiated with very high-energy protons and spallation neutrons showed that irradiation caused significant hardening and loss of uniform elongation. The specimens were irradiated at temperatures from room temperature to 150°C in the Los Alamos Spallation Radiation Effects Facility (LASREF) at the Los Alamos Neutron Scattering Center (LANSCE). Dose levels ranged from 0.01 to 12 dpa. Most of the observed hardening for all three alloys occurred within the first 0.1 dpa (i.e., low dose) and before significant gas accumulation, indicating that gas generation may not play a significant role in the hardening or ductility loss. The correlations between tensile and shear punch data were as expected for yield strength but were unusual for the maximum strength in comparison with previous correlations based on fission-neutron-irradiated alloys.

Hamilton, M. L.; Garner, F. A.; Toloczko, M. B.; Maloy, S. A.; Sommer, W. F.; James, M. R.; Ferguson, P. D.; Louthan, M. R.

2000-12-01

385

Tensile properties of V-Cr-Ti alloys after exposure in oxygen-containing environments  

SciTech Connect

A systematic study was conducted to evaluate the oxidation kinetics of V-4Cr-4Ti (44 alloy) and V-5Cr-5Ti alloys (55 alloy) and to establish the role of oxygen ingress on the tensile behavior of the alloys at room temperature and at 500 C. The oxidation rate of the 44 alloy is slightly higher than that of the 55 alloy. The oxidation process followed parabolic kinetics. Maximum engineering stress for 55 alloy increased with an increase in oxidation time at 500 C. The maximum stress values for 55 alloy were higher at room temperature than ta 500 C for the same oxidation treatment. Maximum engineering stresses for 44 alloy were substantially lower than those for 55 alloy in the same oxidation {approx}500 h exposure in air at 500 C; the same values were 4.8 and 6.1%, respectively, at 500 C after {approx}2060 h oxidation in air at 500 C. Maximum engineering stress for 44 alloy at room temperature was 421.6--440.6 MPa after {approx}250 h exposure at 500 C in environments with a pO{sub 2} range of 1 {times} 10{sup {minus}6} to 760 torr. The corresponding uniform and total elongation values were 11--14.4% and 14.5--21.7%, respectively. Measurements of crack depths in various specimens showed that depth is independent of pO{sub 2} in the preexposure environment and was of 70--95 {micro}m after 250--275 h exposure at 500 C.

Natesan, K.; Soppet, W.K. [Argonne National Lab., IL (United States)

1998-03-01

386

Effect of 475 C embrittlement on fractal behavior and tensile properties of a duplex stainless steel  

SciTech Connect

The fractal dimension variations of several tension surfaces of a duplex stainless steel broken at room temperature has been studied after several aging treatments performed at 475 C for 1, 2, 6.5, 12, 24, 40, and 120 h. A dimple type of fracture mode was observed for small aging times and transgranular as well as dimple rupture for 24, 40, and 120 h of aging. The higher the time of aging is, the smaller the fractal dimension and the true fracture strain. An expected reduction of the strength with the time of aging was observed.

Hilders, O.A.; Ramos, M.; Pena, N.D. [Central Univ. of Venezuela, Caracas (Venezuela). School of Metallurgical Engineering and Materials Science] [Central Univ. of Venezuela, Caracas (Venezuela). School of Metallurgical Engineering and Materials Science; Saenz, L. [Univ. of Carabobo, Valencia (Venezuela). Dept. of Materials and Fabrication Processes] [Univ. of Carabobo, Valencia (Venezuela). Dept. of Materials and Fabrication Processes

1999-02-01

387

Optimization of quenching process in hot press forming of 22MnB5 steel for high strength properties for publication in  

NASA Astrophysics Data System (ADS)

This paper presents hot press forming of 22MnB5 steel blanks for high strength automotive components. The hot press forming was performed using Schenck press PEZ0673 machine with maximum press force of 1000 kN. Samples were square 22MnB5 blanks, of 50 × 60 mm dimension. A high temperature furnace was used to heat up the blanks to austenite temperature of 950°C. Samples were held at the austenite temperature prior to forming and quenching process. Three independent controlled parameters were cooling water temperature, press holding time and flow rate of water. Pressed samples were characterized for metallographic study, hardness properties and tensile properties. Metallographic study was conducted using Meiji optical microscope. Hardness was measured using Vickers indenter with load 1000gf. From metallographic study, the hot pressed 22MnB5 boron steel samples produced lath martensitic microstructure. Hardness of hot pressed samples increased with decreasing cooling time. The yield strength and the ultimate tensile strength of samples after hot forming were between 1546 and 1923 N/mm2. These findings were important to design tailored ultra-high strength in automotive components at different process parameter settings.

Aziz, Nuraini; Aqida, S. N.

2013-12-01

388

Rate effect on mechanical properties of hydraulic concrete flexural-tensile specimens under low loading rates using acoustic emission technique.  

PubMed

Acoustic emission (AE) waveform is generated by dislocation, microcracking and other irreversible changes in a concrete material. Based on the AE technique (AET), this paper focuses on strain rate effect on physical mechanisms of hydraulic concrete specimens during the entire fracture process of three point bending (TPB) flexural tests at quasi-static levels. More emphasis is placed on the influence of strain rate on AE hit rate and AE source location around peak stress. Under low strain rates, namely 0.77×10(-7)s(-1), 1×10(-7)s(-1) to 1×10(-6)s(-1) respectively, the results show that the tensile strength increases as the strain rate increases while the peak AE hit rate decreases. Meanwhile, the specimen under a relatively higher strain rate shows a relatively wider intrinsic process zone in a more diffuser manner, lots of distributed microcracks relatively decrease stress intensity, thus delay both microcracking localization and macrocrack propagation. These phenomena can be attributed to Stéfan effect. In addition, further tests, namely the combination of AE monitoring and strain measuring systems was designed to understand the correlation between AE event activity and microfracture (i.e., microcracking and microcracking localization). The relative variation trend of cumulative AE events accords well with that of the load-deformation curve. PMID:22534061

Su, Huaizhi; Hu, Jiang; Tong, Jianjie; Wen, Zhiping

2012-09-01

389

Tensile city  

E-print Network

Tensile City is a story that provides the answer to the following question: II If we were to leap forward in time and visit a city of the future, what would learn about our contemporary city ? II The story unfolds when ...

Chakkour, Mario Henri

1987-01-01

390

Internal hydrogen effects on tensile properties of iron- and nickel-base superalloys  

SciTech Connect

Two nickel-base alloys (IN718) and (IN625) and one iron-base superalloy (A286) have been chosen to study the effects of internal H charging on their room-temperature slow strain rate mechanical behavior.Uniform internal H contents ranged from 0 to 50 wt ppm H (0 to 3000 at. ppm H), and a strain rate of 8.5 {times} 10{sup {minus} 7} m/s was used with notched strip specimens. The three alloys showed varying losses in strength and ductility, and the strongest alloy, IN718, showed a decrease of 67 pct in ductility for a dissolved H content of 40 wt ppm. Superalloy A286 showed a corresponding 50 pct decrease in ductility, and IN625 showed a 29 pct loss in ductility. Fractographic evidence and the decrease in strength lead the authors to conclude that the enhanced localized plasticity mechanism for H embrittlement is possibly operative in these face-centered cubic (fcc) alloys.

Hicks, P.D.; Altstetter, C.J. (Illinois Univ., Urbana, IL (USA). Dept. of Materials Science and Engineering)

1990-02-01

391

Internal hydrogen effects on tensile properties of iron- and nickel-base superalloys  

NASA Astrophysics Data System (ADS)

Two nickel-base alloys [superalloys INCONEL 718 (IN718) and INCONEL 625 (IN625)] and one iron-base superalloy (A286) were chosen to study the effects of internal H charging on their room-temperature slow strain rate mechanical behavior. Uniform internal H contents ranged from 0 to 50 wt ppm H (0 to 3000 at. ppm H), and a strain rate of 8.5 X 10-7 m/s was used with notched strip specimens. The three alloys showed varying losses in strength and ductility, and the strongest alloy, IN718, showed a decrease of 67 pet in ductility for a dissolved H content of 40 wt ppm. Superalloy A286 showed a corresponding 50 pet decrease in ductility, and IN625 showed a 29 pet loss in ductility. Fractographic evidence and the marked decrease in strength of the alloys lead the authors to conclude that the enhanced localized plasticity mechanism for H embrittlement is possibly operative in these face-centered cubic (fcc) alloys.

Hicks, P. D.; Altstetter, C. J.

1990-01-01

392

Methane gas hydrate effect on sediment acoustic and strength properties  

USGS Publications Warehouse

To improve our understanding of the interaction of methane gas hydrate with host sediment, we studied: (1) the effects of gas hydrate and ice on acoustic velocity in different sediment types, (2) effect of different hydrate formation mechanisms on measured acoustic properties (3) dependence of shear strength on pore space contents, and (4) pore pressure effects during undrained shear. A wide range in acoustic p-wave velocities (Vp) were measured in coarse-grained sediment for different pore space occupants. Vp ranged from less than 1 km/s for gas-charged sediment to 1.77–1.94 km/s for water-saturated sediment, 2.91–4.00 km/s for sediment with varying degrees of hydrate saturation, and 3.88–4.33 km/s for frozen sediment. Vp measured in fine-grained sediment containing gas hydrate was substantially lower (1.97 km/s). Acoustic models based on measured Vp indicate that hydrate which formed in high gas flux environments can cement coarse-grained sediment, whereas hydrate formed from methane dissolved in the pore fluid may not. The presence of gas hydrate and other solid pore-filling material, such as ice, increased the sediment shear strength. The magnitude of that increase is related to the amount of hydrate in the pore space and cementation characteristics between the hydrate and sediment grains. We have found, that for consolidation stresses associated with the upper several hundred meters of sub-bottom depth, pore pressures decreased during shear in coarse-grained sediment containing gas hydrate, whereas pore pressure in fine-grained sediment typically increased during shear. The presence of free gas in pore spaces damped pore pressure response during shear and reduced the strengthening effect of gas hydrate in sands.

Winters, W.J.; Waite, W.F.; Mason, D.H.; Gilbert, L.Y.; Pecher, I.A.

2007-01-01

393

Effect of conditioning temperature on the strength and permeability of normal- and high-strength concrete  

Microsoft Academic Search

In order to evaluate the effect of the conditioning temperature on strength and permeability properties of concrete a series of compressive, indirect tensile and permeability tests were performed on concretes (designed to have 28-day compressive strengths of 40 and 100 N\\/mm2) conditioned at temperatures of 85 and 105 °C. The results show that, for both the normal- (NSC) and the

D. R. Gardner; R. J. Lark; B. Barr

2005-01-01

394

Effects of Oxides on Tensile and Charpy Impact Properties and Fracture Toughness in Heat Affected Zones of Oxide-Containing API X80 Linepipe Steels  

NASA Astrophysics Data System (ADS)

This study is concerned with effects of complex oxides on acicular ferrite (AF) formation, tensile and Charpy impact properties, and fracture toughness in heat affected zones (HAZs) of oxide-containing API X80 linepipe steels. Three steels were fabricated by adding Mg and O2 to form oxides, and various HAZ microstructures were obtained by conducting HAZ simulation tests under different heat inputs. The no. of oxides increased with increasing amount of Mg and O2, while the volume fraction of AF present in the steel HAZs increased with increasing the no. of oxides. The strengths of the HAZ specimens were generally higher than those of the base metals because of the formation of hard microstructures of bainitic ferrite and granular bainite. When the total Charpy absorbed energy was divided into the fracture initiation and propagation energies, the fracture initiation energy was maintained constant at about 75 J at room temperature, irrespective of volume fraction of AF. The fracture propagation energy rapidly increased from 75 to 150 J and saturated when the volume fraction of AF exceeded 30 pct. At 253 K (-20 °C), the total absorbed energy increased with increasing volume fraction of AF, as the cleavage fracture was changed to the ductile fracture when the volume fraction of AF exceeded 45 pct. Thus, 45 vol pct of AF at least was needed to improve the Charpy impact energy, which could be achieved by forming a no. of oxides. The fracture toughness increased with increasing the no. of oxides because of the increased volume fraction of AF formed around oxides. The fracture toughness did not show a visible correlation with the Charpy absorbed energy at room temperature, because toughness properties obtained from these two toughness testing methods had different significations in view of fracture mechanics.

Sung, Hyo Kyung; Sohn, Seok Su; Shin, Sang Yong; Oh, Kyung Shik; Lee, Sunghak

2014-06-01

395

Tensile property and interfacial dewetting in the calcite filled HDPE, LDPE, and LLDPE composites  

Microsoft Academic Search

Mechanical properties and complex melt viscosity of unfilled and the calcite (calcium carbonate: CaCO3) filled high density polyethylene (HDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE) composites using dumbbell bar and film specimens are studied. In addition, the formation of air holes between calcium carbonate and the resin matrix was investigated from the phase morphology and interfacial

Sangmin Kwon; Kwang J Kim; Hyun Kim; Patit P Kundu; Tae J Kim; Young K Lee; Byung H Lee; Soonja Choe

2002-01-01

396

Effect of irradiation on the fracture behavior and tensile properties of an HT9 duct  

Microsoft Academic Search

Alloy HT9 is a leading candidate material for Liquid Metal Reactor applications because of insignificant swelling and low thermal expansion. To evaluate applications for this alloy, the ACO-1 experiment was conducted. The HT9 alloy was used for cladding and duct for the FFTF Test Assembly. A part of the postirradiation portion of the experiment was the mechanical property testing of

1989-01-01

397

Microsample characterization of the tensile and compressive mechanical properties of single crystalline gamma-TiAl  

NASA Astrophysics Data System (ADS)

Titanium-aluminide intermetallic compounds are promising as high temperature structural materials in both the automotive and gas turbine industries, because of their low density, relatively high Young's modulus and yield strength. The commercially used TiAl intermetallic alloys will most likely have a two-phase fully lamellar structure. However, due to the complex nature of these alloys this study focuses on the single-phase gamma, since it will be the major constituent in the two-phase materials and dislocation activity in two-phase alloys is believed to occur most readily in the gamma-TiAl phase. Previously, the lack of sufficiently large high quality single crystals has precluded mechanical testing of gamma-TiAl in tension. In the present study, single crystals of gamma-Ti 55.5at%Al have been grown, oriented and cut into microsample tension/compression specimens with nominal dimensions of 3mm x 1mm. The small size of the microsample allows for both tension and compression testing of single crystals of gamma-Ti 55.5at%Al as a function of temperature and crystallographic orientation. Single crystal microsample test specimens of gamma-Ti 55.5at%Al oriented along the ˜[001], ˜[010] and ˜[-110] crystal axes have been deformed in tension, compression, fully reversed compression-tension and fully reversed tension-compression tests at temperatures ranging from 723 K to 1273 K From these experiments measurements of the Young's modulus, coefficient of thermal expansion and 0.2% offset flow stress have been made as a function of temperature, crystal orientation and sense of applied load in the anomalous yielding regime. A measurable flow strength anomaly is observed for all three orientations and a significant tension/compression asymmetry has been measured in the anomalous yielding temperature region. The asymmetric dissociation and motion of superdislocations, their ability to cross-slip under applied loads, the anisotropic interaction forces between dislocations and the constriction forces on dislocations have all been analyzed to determine their role in the cross-slip locking processes of superdislocations. The formation of locks is most favorable when the applied stress promotes cross-slip of the trailing dissociated superpartial onto the secondary octahedral plane, and is used to explain the flow stress anomaly, tension/compression asymmetry and the Schmid's law violations that have been measured.

Zupan, Marc P.

398

Influence of Sludge Particles on the Tensile Properties of Die-Cast Secondary Aluminum Alloys  

NASA Astrophysics Data System (ADS)

The effects of sludge intermetallic particles on the mechanical properties of a secondary AlSi9Cu3(Fe) die-casting alloy have been studied. Different alloys have been produced by systematically varying the Fe, Mn, and Cr contents within the composition tolerance limits of the standard EN AC-46000 alloy. The microstructure shows primary ?-Al x (Fe,Mn,Cr) y Si z sludge particles, with polyhedral and star-like morphologies, although the presence of primary ?-Al5FeSi phase is also observed at the highest Fe:Mn ratio. The volume fraction of primary compounds increases as the Fe, Mn, and Cr contents increase and this can be accurately predicts from the Sludge Factor by a linear relationship. The sludge amount seems to not influence the size and the content of porosity in the die-cast material. Furthermore, the sludge factor is not a reliable parameter to describe the mechanical properties of the die-cast AlSi9Cu3(Fe) alloy, because this value does not consider the mutual interaction between the elements. In the analyzed range of composition, the design of experiment methodology and the analysis of variance have been used in order to develop a semi-empirical model that accurately predicts the mechanical properties of the die-cast AlSi9Cu3(Fe) alloys as function of Fe, Mn, and Cr concentrations.

Ferraro, Stefano; Timelli, Giulio

2014-12-01

399

Strength degradation of glass fibers at high temperatures  

Microsoft Academic Search

This article presents an experimental investigation into the effects of temperature and heating time on the tensile strength\\u000a and failure mechanisms of glass fibers. The loss in strength of two glass fiber types (E-glass and Advantex®, a boron-free version of E-glass) was investigated at temperatures up to 650 °C and heating times up to 2 h. The tensile\\u000a properties were measured by

S. Feih; K. Manatpon; Z. Mathys; A. G. Gibson; A. P. Mouritz

2009-01-01

400

Tensile Behavior of Al2o3/feal + B and Al2o3/fecraly Composites  

NASA Technical Reports Server (NTRS)

The feasibility of Al2O3/FeAl + B and Al2O3/FeCrAlY composites for high-temperature applications was assessed. The major emphasis was on tensile behavior of both the monolithics and composites from 298 to 1100 K. However, the study also included determining the chemical compatibility of the composites, measuring the interfacial shear strengths, and investigating the effect of processing on the strength of the single-crystal Al2O3 fibers. The interfacial shear strengths were low for Al203/FeAl + B and moderate to high for Al203/FeCrAlY. The difference in interfacial bond strengths between the two systems affected the tensile behavior of the composites. The strength of the Al203 fiber was significantly degraded after composite processing for both composite systems and resulted in poor composite tensile properties. The ultimate tensile strength (UTS) values of the composites could generally be predicted with either rule of mixtures (ROM) calculations or existing models when using the strength of the etched-out fiber. The Al2O3/FeAl + B composite system was determined to be unfeasible due to poor interfacial shear strengths and a large mismatch in coefficient of thermal expansion (CTE). Development of the Al2O3/FeCrAlY system would require an effective diffusion barrier to minimize the fiber strength degradation during processing and elevated temperature service.

Draper, S. L.; Eldridge, J. I.; Aiken, B. J. M.

1995-01-01

401

Tensile properties from room temperature to 1315 C of tungsten-lined tantalum-alloy (T-111) tubing fabricated by hot isostatic pressing  

NASA Technical Reports Server (NTRS)

The effects were studied of a thin tungsten liner on the tensile properties of T-111 tubing considered for fuel cladding in a space power nuclear reactor concept. The results indicate that the metallurgically bonded liner had no appreciable effects on the properties of the T-111 tubing. A hot isostatic pressing method used to apply the liners is described along with a means for overcoming the possible embrittling effects of hydrogen contamination.

Buzzard, R. J.; Metroka, R. R.

1974-01-01

402

Properties of high-strength cladded plate in tension  

Microsoft Academic Search

1.The strength of cladded steel VKS-1 in biaxial tension reaches values 20–25% higher than that of the homogeneous steel.2.For cladded high-strength steel the use of electroslag remelting increases the ductility, but to a lesser extent than for the homogeneous steel.

P. O. Pashkov; A. A. Yavor; É. A. Savchenkov; N. V. Kotov; N. M. Sklyarov; A. A. Mikheev; A. A. Platonov

1973-01-01

403

Effect of concurrent strength and endurance training on skeletal muscle properties and hormone concentrations in humans  

Microsoft Academic Search

The purpose of this study was to investigate the effect of concurrent strength and endurance training on strength, endurance,\\u000a endocrine status and muscle fibre properties. A total of 45 male and female subjects were randomly assigned to one of four\\u000a groups; strength training only (S), endurance training only (E), concurrent strength and endurance training (SE), or a control\\u000a group (C).

G. J. Bell; D. Syrotuik; T. P. Martin; R. Burnham; H. A. Quinney

2000-01-01

404

Hot tensile properties and deformation response of a gamma/Ni/-gamma prime/Ni3Al/-delta/Ni3Nb/ eutectic composite  

NASA Technical Reports Server (NTRS)

Three distinct regions of tensile, deformation and fracture behavior were observed in a 2.5 wt. per cent Al gamma/gamma prime-delta eutectic alloy as the testing temperature was varied. The major finding was an extraordinary ductility maximum at about 550 C. It was shown that this phenomenon is caused by the deflection of transverse cracks at the eutectic grain boundaries when yielding occurs. This delamination between eutectics grains caused by fracture of a gamma prime eutectic grain boundary film leads to a distinctly different 'wood-like' fracture surface morphology. Above 690 C to 926 C, yield and tensile strength values decrease while ductility increase slightly. Cooperative twinning of both phases develops giving rise to block-like deformation of the microstructure quite in parallel to the behavior observed previously in the gamma-delta system.

Bertorello, H. R.; Hertzberg, R. W.; Kraft, R. W.

1975-01-01

405

THE EFFECT OF PRECURSOR PROPERTIES ON THE STRENGTH OF CARBON FIBER  

Microsoft Academic Search

In this article, lyocell fiber is used as a precursor for carbon fiber. The mechanical properties of lyocell fiber and tenacity of carbon fiber from this precursor have been determined. Gray-relation analysis is used to investigate the relation between precursor's properties and the strength of the carbon fibers. The results suggested that the strength, force at breaking, and fineness of

Shunjin Peng; Huili Shao; Xuechao Hu

2004-01-01

406

Early age properties of high-strength\\/high-performance concrete  

Microsoft Academic Search

Analyses and results of tests on heat of hydration and compressive strength of high-performance concrete cured in variable thermal conditions are presented in this paper. Investigations of hydration heat of cement were carried out in calorimeter, in adiabatic conditions. Test samples for strength tests were stored in isothermal conditions at temperature of T=8°C, 20°C, 35°C, and in adiabatic conditions at

Maria Kaszy?ska

2002-01-01

407

Tensile Testing: A Simple Introduction  

ERIC Educational Resources Information Center

Tensile testing may be used to decide, say, which steel to use in various constructions. Analogous testing can be done simply in the classroom using plasticine and helps to introduce pupils to the various properties studied in materials science.

Carr, Martin

2006-01-01

408

Fatigue analysis for a multi-lap spot welded joint of high strength steel using quasi static tensile-shear test  

Microsoft Academic Search

The welding quality of spot weldment is an important factor that significantly affects the strength, stiffness, safety, and\\u000a other performance characteristics of vehicles. Therefore, quality control and fatigue life evaluation of spot weldment are\\u000a necessary processes. This paper presents a method for determining the fatigue life of multi-lap spot weldment of a high strength\\u000a steel sheet. In this method, the

S. R. Sin; S. M. Yang; H. S. Yu; C. W. Kim; H. Y. Kang

2008-01-01

409

Diffusion Bonding of Microduplex Stainless Steel and Ti Alloy with and without Interlayer: Interface Microstructure and Strength Properties  

NASA Astrophysics Data System (ADS)

The interface microstructure and strength properties of solid state diffusion bonding of microduplex stainless steel (MDSS) to Ti alloy (TiA) with and without a Ni alloy (NiA) intermediate material were investigated at 1173 K (900 °C) for 0.9 to 5.4 ks in steps of 0.9 ks in vacuum. The effects of bonding time on the microstructure of the bonded joint have been analyzed by light optical microscopy and scanning electron microscopy in the backscattered mode. In the direct bonded joints of MDSS and TiA, the layer-wise ? phase and the ? + FeTi phase mixture were observed at the bond interface when the joint was processed for 2.7 ks and above holding times. However, when NiA was used as an intermediate material, the results indicated that TiNi3, TiNi, and Ti2Ni are formed at the NiA-TiA interface, and the irregular shaped particles of Fe22Mo20Ni45Ti13 have been observed within the TiNi3 intermetallic layer. The stainless steel-NiA interface is free from intermetallics and the layer of austenitic phase was observed at the stainless steel side. A maximum tensile strength of ~520 MPa, shear strength of ~405 MPa, and impact toughness of ~18 J were obtained for the directly bonded joint when processed for 2.7 ks. However, when nickel base alloy was used as an intermediate material in the same materials, the bond tensile and shear strengths increase to ~640 and ~479 MPa, respectively, and the impact toughness to ~21 J when bonding was processed for 4.5 ks. Fracture surface observations in scanning electron microscopy using energy dispersive spectroscopy demonstrate that in MDSS-TiA joints, failure takes place through the FeTi + ? phase when bonding was processed for 2.7 ks; however, failure takes place through ? phase for the diffusion joints processed for 3.6 ks and above processing times. However, in MDSS-NiA-TiA joints, the fracture takes place through NiTi2 layer at the NiA-TiA interface for all bonding times.

Kundu, S.; Sam, S.; Mishra, B.; Chatterjee, S.

2014-01-01

410

Static and Dynamic Flexural Strength Anisotropy of Barre Granite  

NASA Astrophysics Data System (ADS)

Granite exhibits anisotropy due to pre-existing microcracks under tectonic loadings; and the mechanical property anisotropy such as flexural/tensile strength is vital to many rock engineering applications. In this paper, Barre Granite is studied to understand the flexural strength anisotropy under a wide range of loading rates using newly proposed semi-circular bend tests. Static tests are conducted with a MTS hydraulic servo-control testing machine and dynamic tests with a split Hopkinson pressure bar (SHPB) system. Six samples groups are fabricated with respect to the three principle directions of Barre granite. Pulse shaping technique is used in all dynamic SHPB tests to facilitate dynamic stress equilibrium. Finite element method is utilized to build up equations calculating the flexural tensile strength. For samples in the same orientation group, a loading rate dependence of the flexural tensile strength is observed. The measured flexural tensile strength is higher than the tensile strength measured using Brazilian disc method at given loading rate and this scenario has been rationalized using a non-local failure theory. The flexural tensile strength anisotropy features obvious dependence on the loading rates, the higher the loading rate, the less the anisotropy and this phenomenon may be explained considering the interaction of the preferentially oriented microcracks.

Dai, F.; Xia, K.; Zuo, J. P.; Zhang, R.; Xu, N. W.

2013-11-01

411

Relating Diffuse Interstellar Band Strengths to Line of Sight Properties  

NASA Astrophysics Data System (ADS)

We present a preliminary analysis of a set of optical (3800-8800 Å) high resolution (R = 80,000) spectra for 69 diffuse interstellar band targets. We carried out a sensitive search for interstellar features in the wavelength range 8470-8740 Å that will be covered by the upcoming GAIA mission. We also investigate how the ?8620Å DIB strength varies as a function of other interstellar parameters (other DIBs, E(B-V) and atomic and molecular column densities).

Rashedi, H.; Cami, J.; Cox, N. L. J.; van Winckel, H.

2014-02-01

412

Strength properties of autoclaved cellular concrete with high volume fly ash  

Microsoft Academic Search

This paper presents the results of an investigation on the strength properties of autoclaved cellular concrete (ACC) blocks, a building material that can contain up to 70% w\\/w of electric utility fly ash. The scope of this investigation covers three phases: (1) a brief literature review; (2) a selection of optimum strength testing methods suitable for ACC materials; and (3)

Wenyi Hu; Ronald D. Neufeld; Luis E. Vallejo; Christopher Kelly; Martin Latona

1997-01-01

413

Correlations Between Index Properties and Unconfined Compressive Strength of Weathered Ocala Limestone  

Microsoft Academic Search

Weathering has a negative effect on both physical and engineering properties of rock specimens and rock masses. When rock masses are weathered it is often difficult to obtain core segments that are the correct size for unconfined compressive strength testing. Thus engineers must use index testing to estimate the strength of specimens for design purposes. This thesis relates the unconfined

Raoaa Farah

2011-01-01

414