Science.gov

Sample records for highly deformed states

  1. Anisotropy and oxidative resistance of highly crosslinked UHMWPE after deformation processing by solid-state ram extrusion.

    PubMed

    Kurtz, Steven M; Mazzucco, Dan; Rimnac, Clare M; Schroeder, Dave

    2006-01-01

    Solid-state deformation processing is a promising technique for modifying the physical and mechanical properties of highly crosslinked ultra-high molecular weight polyethylene (UHMWPE) beyond simple thermal treatment cycles that have been employed previously. This study evaluates anisotropy and oxidative resistance in a novel, radiation crosslinked (50 kGy) UHMWPE material (ArComXL: Biomet, Inc., Warsaw, IN), incorporating solid-state, deformation processing by extrusion below the melt transition for application in total hip arthroplasty. Tensile, compression, and small punch tests were conducted to evaluate the material properties in the three principal axes of the resulting material. Furthermore, short-term oxidative resistance was evaluated using Fourier transform infrared spectroscopy and the small punch test in conjunction with accelerated shelf aging protocols. The results of this testing indicate that the material is anisotropic, with significantly enhanced strength oriented along the long axis of the rod. For certain other properties, the magnitude of the anisotropy was relatively slight, especially in the elastic regime, in which only a 20% difference was noted between the long axis of the rod and the orthogonal, radial direction. The highly crosslinked material contains detectable free radicals, at a concentration that is 90% less than control, gamma inert sterilized UHMWPE. An unexpected finding of this study was evidence of oxidative stability of the deformation-processed material, even after 4 weeks of accelerated aging in a pressure vessel containing five atmospheres of oxygen (ASTM F2003), which resulted in macroscopic embrittlement of the control material. The oxidative stability observed in ArComXL suggests that the deformation-processed material may be suitable for air-permeable packaging and gas sterilization, which has thus far been reserved for remelted highly crosslinked UHMWPE.

  2. High Temperature Solid-State Coeval Brittle and Ductile Deformation during Cooling of Lake Edison Granodiorite (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Pennacchioni, G.

    2009-12-01

    In the Lake Edison (LE) granodiorite (88Ma) of the Bear Creek area (Cretaceous Mono Pass intrusive suite, Sierra Nevada, CA) different sets of fractures developed during the high temperature stages of post-magmatic cooling. These fractures strongly localized successive ductile and later brittle shear deformation, but many pristine fractures do not show any shear offset (i.e. are joints). Away from the contact with the younger (86Ma) Mono Creek granite, the LE granodiorite mainly show a single dominant set of steeply dipping fractures striking around E-W to ENE-WSW which were exploited as left-handed strike-slip ductile shear zones and later as faults with identical kinematics. In the proximity of the contact, a second (dominant) set of steeply dipping fractures is present, striking about NNE-SSW, with a right-handed ductile shear reactivation and forming a conjugate array with the E-W set; many leucocratic dykes (including pegmatite) also localized the shear deformation within the granodiorite. Left-handed shear zones commonly overprint the right-handed ones, but the opposite is also observed which suggests that the two sets developed at the same time. Ductile shear zones are associated with a background solid state foliation in the host granodiorite which is mainly developed towards the contact and which has been referred to the Rosy Finch Shear Zone in the area. The mineral fabric along the foliation and along both the left- and right-handed localized shear zones indicate deformation T>500°C. The overall structural association is consistent with a regional shortening direction oriented about NW-SE. Fractures, including joints (occurring with the same orientation of the conjugate shear fractures), which form the precursory structures of shear zones, developed at the same time of ductile deformation and locally overprint the shear zones. The geometry and spatial arrangement of these precursory fractures control the patterns of ductile deformation of the host rocks

  3. Paleotectonic control on distribution of long-term deformation in the Central United States from high-resolution seismic data

    NASA Astrophysics Data System (ADS)

    Magnani, M.; McIntosh, K. D.; Guo, L.

    2011-12-01

    The theory of plate tectonics has provided earth science with a framework to explain why the majority of earthquakes occur at plate boundaries. By contrast, the processes leading to intraplate earthquakes are still poorly understood worldwide because a) the very occurrence of such earthquakes violate plate tectonic theory; b) these earthquakes have long recurrence intervals due to intrinsic low strain rates imposed by far field plate boundary forces, and c) they occur in relatively tectonically quiescent areas where major intracontinental structures are buried/unexposed, and therefore poorly understood. While we know that intraplate earthquakes result from plate-driving forces transmitted through plate interiors, we still do not understand what controls the spatial and temporal pattern of these events. One of the most studied intracontinental seismic zones in the world is the central United States, home to the New Madrid seismic zone, where repeated large magnitude earthquakes have shaken the ground for the past few thousands years, but little deformation is measured at the surface and observed in the subsurface. In the past few years several lines of evidence have emerged showing that currently aseismic portions of the central United States have been the location of large magnitude earthquakes in the recent past (Holocene). Here we summarize the main results of the Moonwalk Project, a ~950 km-long high-resolution marine seismic reflection and CHIRP profile acquired on the Mississippi River from Cape Girardeau, Missouri, to Lake Providence, Louisiana. The profile images the New Madrid fault system as well as several additional faults outside the active fault zone (e.g. the Meeman-Shelby Fault - see Hao et al., this session), where the deformed river alluvium constrains the youngest age of deformation to the Holocene. The data also illuminate liquefaction-induced structures at few locations, one of them located at the Arkansas/Louisiana border, ~360 km south of the

  4. Characterizing the deformed state in Al-0.1 Mg alloy using high-resolution electron backscattered diffraction.

    PubMed

    Hurley, P J; Humphreys, F J

    2002-03-01

    The application of high resolution electron backscatter diffraction (EBSD) in a field emission gun scanning electron microscope to the characterization of a deformed aluminium alloy is discussed and the results are compared with those obtained by transmission electron microscopy. It is shown that the adequate spatial resolution, accompanied by the improvement in angular resolution to approximately 0.5 degrees that can be achieved by data processing, together with the extensive quantitative data obtainable, make EBSD a suitable method for characterizing the cell or subgrain structures in deformed aluminium. The various methods of analysing EBSD data to obtain subgrain sizes are discussed and it is concluded that absolute subgrain reconstruction is the most accurate.

  5. State-variable theories for nonelastic deformation

    SciTech Connect

    Li, C.Y.

    1981-01-01

    The various concepts of mechanical equation of state for nonelastic deformation in crystalline solids, originally proposed for plastic deformation, have been recently extended to describe additional phenomena such as anelastic and microplastic deformation including the Bauschinger effect. It has been demonstrated that it is possible to predict, based on current state variables in a unified way, the mechanical response of a material under an arbitrary loading. Thus, if the evolution laws of the state variables are known, one can describe the behavior of a material for a thermal-mechanical path of interest, for example, during constant load (or stress) creep without relying on specialized theories. Some of the existing theories of mechanical equation of state for nonelastic deformation are reviewed. The establishment of useful forms of mechanical equation of state has to depend on extensive experimentation in the same way as that involved in the development, for example, the ideal gas law. Recent experimental efforts are also reviewed. It has been possible to develop state-variable deformation models based on experimental findings and apply them to creep, cyclic deformation, and other time-dependent deformation. Attempts are being made to correlate the material parameters of the state-variable models with the microstructure of a material. 24 figures.

  6. Deformation of partially pumped active mirrors for high average-power diode-pumped solid-state lasers.

    PubMed

    Albach, Daniel; LeTouzé, Geoffroy; Chanteloup, Jean-Christophe

    2011-04-25

    We discuss the deformation of a partially pumped active mirror amplifier as a free standing disk, as implemented in several laser systems. We rely on the Lucia laser project to experimentally evaluate the analytical and numerical deformation models.

  7. Mechanical biocompatibility of highly deformable biomedical materials.

    PubMed

    Mazza, Edoardo; Ehret, Alexander E

    2015-08-01

    Mismatch of mechanical properties between highly deformable biomedical materials and adjacent native tissue might lead to short and long term health impairment. The capability of implants to deform at the right level, i.e. similar to the macroscopic mechanical response of the surrounding biological materials, is often associated with dissimilar microstructural deformation mechanisms. This mismatch on smaller length scales might lead to micro-injuries, cell damage, inflammation, fibrosis or necrosis. Hence, the mechanical biocompatibility of soft implants depends not only on the properties and composition of the implant material, but also on its organization, distribution and motion at one or several length scales. The challenges related to the analysis and attainment of mechanical biocompatibility are illustrated with two examples: prosthetic meshes for hernia and pelvic repair and electrospun scaffolds for tissue engineering. For these material systems we describe existing methods for characterization and analysis of the non-linear response to uniaxial and multiaxial stress states, its time and history dependence, and the changes in deformation behavior associated with tissue in-growth and material resorption. We discuss the multi-scale deformation behavior of biomaterials and adjacent tissue, and indicate major interdisciplinary questions to be addressed in future research. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Deformation of high-temperature superconductors

    SciTech Connect

    Goretta, K.C.; Routbort, J.L.; Miller, D.J.; Chen, N.; Dominguez-Rodriguez, A.; Jimenez-Melendo, M.; De Arellano-Lopez, A.R.

    1994-08-01

    Of the many families of high-temperature superconductors, only the properties of those discovered prior to 1989 - Y-Ba-Cu-O, Tl-Ba(Sr)-Ca-Cu-O, and Bi(Pb)-Sr-Ca-Cu-O - have been studied extensively. Deformation tests have been performed on YBa{sub 2}Cu{sub 3}O{sub x} (Y-123), YBa{sub 2}Cu{sub 4}O{sub x} (Y-124), TlBa{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} (Bi-2223). The tests have revealed that plasticity is generally limited in these compounds and that the rate-controlling diffusional kinetics for creep are very slow. Nevertheless, hot forming has proved to be quite successful for fabrication of bulk high-temperature superconductors, so long as deformation rates are low or large hydrostatic stresses are applied. Steady-state creep data have proved to be useful in designing optimal heat treatments for superconductors and in support of more-fundamental diffusion experiments. The high-temperature superconductors are highly complex oxides, and it is a challenge to understand their deformation responses. In this paper, results of interest and operant creep mechanisms will be reviewed.

  9. Deformable mirror for high power laser applications

    NASA Astrophysics Data System (ADS)

    Mrň; a, Libor; Sarbort, Martin; Hola, Miroslava

    2015-01-01

    The modern trend in high power laser applications such as welding, cutting and surface hardening lies in the use of solid-state lasers. The output beam of these lasers is characterized by a Gaussian intensity distribution. However, the laser beams with different intensity distributions, e.g. top-hat, are preferable in various applications. In this paper we present a new type of deformable mirror suitable for the corresponding laser beam shaping. The deformation of the mirror is achieved by an underlying array of actuators and a pressurized coolant that also provides the necessary cooling. We describe the results of the surface shape measurement using a 3D scanner for different settings of actuators. Further, we show the achieved intensity distributions measured by a beam profiler for a low power laser beam reflected from the mirror.

  10. Deformed quons and bi-coherent states

    NASA Astrophysics Data System (ADS)

    Bagarello, F.

    2017-04-01

    We discuss how a q-mutation relation can be deformed replacing a pair of conjugate operators with two other and unrelated operators, as it is done in the construction of pseudo-fermions, pseudo-bosons and truncated pseudo-bosons. This deformation involves interesting mathematical problems and suggests possible applications to pseudo-hermitian quantum mechanics. We construct bi-coherent states associated to D -pseudo-quons, and we show that they share many of their properties with ordinary coherent states. In particular, we find conditions for these states to exist, to be eigenstates of suitable annihilation operators and to give rise to a resolution of the identity. Two examples are discussed in details, one connected to an unbounded similarity map, and the other to a bounded map.

  11. Motion Planning Under Uncertainty In Highly Deformable Environments

    PubMed Central

    Patil, Sachin; van den, Jur; Alterovitz, Berg Ron

    2012-01-01

    Many tasks in robot-assisted surgery, food handling, manufacturing, and other applications require planning and controlling the motions of manipulators or other devices that must interact with highly deformable objects. We present a unified approach for motion planning under uncertainty in deformable environments that maximizes probability of success by accounting for uncertainty in deformation models, noisy sensing, and unpredictable actuation. Unlike prior planners that assume deterministic deformations or treat deformations as a type of small perturbation, our method explicitly considers the uncertainty in large, time-dependent deformations. Our method requires a simulator of deformable objects but places no significant restrictions on the simulator used. We use a sampling-based motion planner in conjunction with the simulator to generate a set of candidate plans based on expected deformations. Our method then uses the simulator and optimal control to numerically estimate time-dependent state distributions based on uncertain parameters (e.g. deformable material properties or actuation errors). We then select the plan with the highest estimated probability of successfully avoiding obstacles and reaching the goal region. Using FEM-based simulation of deformable tissues, we demonstrate the ability of our method to generate high quality plans in two medical-inspired scenarios: (1) guiding bevel-tip steerable needles through slices of deformable tissue around obstacles for minimally invasive biopsies and drug-delivery, and (2) manipulating planar tissues to align interior points at desired coordinates for precision treatment. PMID:25030775

  12. Highly deformable nanofilaments in flow

    NASA Astrophysics Data System (ADS)

    Pawłowska, S.

    2016-10-01

    Experimental analysis of hydrogel nanofilaments conveyed by flow is conducted to help in understanding physical phenomena responsible for transport properties and shape deformations of long bio-objects, like DNA or proteins. Investigated hydrogel nanofilaments exhibit typical macromolecules-like behavior, as spontaneous conformational changes and cross-flow migration. Results of the experiments indicate critical role of thermal fluctuations behavior of single filaments.

  13. Highly deformable bones: unusual deformation mechanisms of seahorse armor.

    PubMed

    Porter, Michael M; Novitskaya, Ekaterina; Castro-Ceseña, Ana Bertha; Meyers, Marc A; McKittrick, Joanna

    2013-06-01

    Multifunctional materials and devices found in nature serve as inspiration for advanced synthetic materials, structures and robotics. Here, we elucidate the architecture and unusual deformation mechanisms of seahorse tails that provide prehension as well as protection against predators. The seahorse tail is composed of subdermal bony plates arranged in articulating ring-like segments that overlap for controlled ventral bending and twisting. The bony plates are highly deformable materials designed to slide past one another and buckle when compressed. This complex plate and segment motion, along with the unique hardness distribution and structural hierarchy of each plate, provide seahorses with joint flexibility while shielding them against impact and crushing. Mimicking seahorse armor may lead to novel bio-inspired technologies, such as flexible armor, fracture-resistant structures or prehensile robotics.

  14. Liquid Droplets on a Highly Deformable Membrane

    NASA Astrophysics Data System (ADS)

    Schulman, Rafael; Dalnoki-Veress, Kari

    2015-11-01

    We present measurements of the deformation produced by micro-droplets atop thin elastomeric and glassy free-standing films. Due to the Laplace pressure, the droplets deform the elastic membrane thereby forming a bulge. Thus, there are two angles that define the droplet/membrane geometry: the angle the liquid surface makes with the film and the angle the deformed bulge makes with the film. The contact line geometry is well captured by a Neumann construction which includes contributions from interfacial and mechanical tensions. Finally, we show that a droplet atop a film with biaxial tension assumes an equilibrium shape which is elongated along the axis of high tension.

  15. Nonclassical Properties of Q-Deformed Superposition Light Field State

    NASA Technical Reports Server (NTRS)

    Ren, Min; Shenggui, Wang; Ma, Aiqun; Jiang, Zhuohong

    1996-01-01

    In this paper, the squeezing effect, the bunching effect and the anti-bunching effect of the superposition light field state which involving q-deformation vacuum state and q-Glauber coherent state are studied, the controllable q-parameter of the squeezing effect, the bunching effect and the anti-bunching effect of q-deformed superposition light field state are obtained.

  16. High-temperature deformation and diffusion in oxides

    SciTech Connect

    Routbort, J.L.

    1992-06-01

    High-temperature, steady-state deformation is usually controlled by diffusion of the slowest moving ion along its fastest diffusion path. Therefore, measurements of steady-state deformation can, in principle, be used to obtain information concerning diffusion. This paper will briefly review the assumptions that relate creep, defect chemistry, and diffusion. Steady-state deformation of the NaCI-structured oxides, Co{sub 1-x}O and Mn{sub l-x}O, and the perovskite-structured high-temperature superconductors YBa{sub 2}Cu{sub 3}0{sub x} and Bi{sub 2}Sr{sub 2}CaCu{sub 2}0{sub x} will be discussed, emphasizing diffusion of the minority defects.

  17. Nuclear ground-state masses and deformations: FRDM(2012)

    DOE PAGES

    Moller, P.; Sierk, A. J.; Ichikawa, T.; ...

    2016-03-25

    Here, we tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A=339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensivemore » and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient LL, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.« less

  18. Nuclear ground-state masses and deformations: FRDM(2012)

    SciTech Connect

    Moller, P.; Sierk, A. J.; Ichikawa, T.; Sagawa, H.

    2016-03-25

    Here, we tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A=339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensive and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient LL, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.

  19. Nuclear ground-state masses and deformations: FRDM(2012)

    NASA Astrophysics Data System (ADS)

    Möller, P.; Sierk, A. J.; Ichikawa, T.; Sagawa, H.

    2016-05-01

    We tabulate the atomic mass excesses and binding energies, ground-state shell-plus-pairing corrections, ground-state microscopic corrections, and nuclear ground-state deformations of 9318 nuclei ranging from 16O to A = 339. The calculations are based on the finite-range droplet macroscopic and the folded-Yukawa single-particle microscopic nuclear-structure models, which are completely specified. Relative to our FRDM(1992) mass table in Möller et al. (1995), the results are obtained in the same model, but with considerably improved treatment of deformation and fewer of the approximations that were necessary earlier, due to limitations in computer power. The more accurate execution of the model and the more extensive and more accurate experimental mass data base now available allow us to determine one additional macroscopic-model parameter, the density-symmetry coefficient L, which was not varied in the previous calculation, but set to zero. Because we now realize that the FRDM is inaccurate for some highly deformed shapes occurring in fission, because some effects are derived in terms of perturbations around a sphere, we only adjust its macroscopic parameters to ground-state masses.

  20. Acoustic emission of coal in the postlimiting deformation state

    SciTech Connect

    Voznesenskii, A.S.; Tavostin, M.N.

    2005-08-01

    The features of acoustic emission in coal samples in the state of pre- and postlimiting deformation are considered. It is shown that in the postlimiting deformation stages and in the transient period, a contrary change is observed in a correlation coefficient of the acoustic emission activity N{Sigma} recorded in the upper and lower portions of a sample; whereas in the prelimiting deformation stages, this change is consistent. It is proposed to recognize the stages of deformation by the correlation coefficient of N{Sigma} recorded in different zones: a positive coefficient corresponds to the prelimiting stage of deformation, and a negative one corresponds to the postlimiting stage.

  1. Grain boundary engineering of highly deformable ceramics

    SciTech Connect

    Mecartney, M.L.

    2000-07-01

    Highly deformable ceramics can be created with the addition of intergranular silicate phases. These amorphous intergranular phases can assist in superplastic deformation by relieving stress concentrations and minimizing grain growth if the appropriate intergranular compositions are selected. Examples from 3Y-TZP and 8Y-CSZ ceramics are discussed. The grain boundary chemistry is analyzed by high resolution analytical TEM is found to have a strong influence on the cohesion of the grains both at high temperature and at room temperature. Intergranular phases with a high ionic character and containing large ions with a relatively weak bond strength appear to cause premature failure. In contrast, intergranular phases with a high degree of covalent character and similar or smaller ions than the ceramic and a high ionic bond strength are the best for grain boundary adhesion and prevention of both cavitation at high temperatures and intergranular fracture at room temperature.

  2. Multiparticle states in deformed special relativity

    SciTech Connect

    Hossenfelder, S.

    2007-05-15

    We investigate the properties of multiparticle states in deformed special relativity (DSR). Starting from the Lagrangian formalism with an energy dependent metric, the conserved Noether current can be derived which is additive in the usual way. The integrated Noether current had previously been discarded as a conserved quantity, because it was correctly realized that it does no longer obey the DSR transformations. We identify the reason for this mismatch in the fact that DSR depends only on the extensive quantity of total four momentum instead of the energy-momentum densities as would be appropriate for a field theory. We argue that the reason for the failure of DSR to reproduce the standard transformation behavior in the well established limits is due to the missing sensitivity to the volume inside which energy is accumulated. We show that the soccer-ball problem is absent if one formulates DSR instead for the field densities. As a consequence, estimates for predicted effects have to be corrected by many orders of magnitude. Further, we derive that the modified quantum field theory implies a locality bound.

  3. q -deformed noncommutative cat states and their nonclassical properties

    NASA Astrophysics Data System (ADS)

    Dey, Sanjib

    2015-02-01

    We study several classical-like properties of q -deformed nonlinear coherent states as well as nonclassical behaviors of q -deformed version of the Schrödinger cat states in noncommutative space. Coherent states in q -deformed space are found to be minimum uncertainty states together with the squeezed photon distributions unlike the ordinary systems, where the photon distributions are always Poissonian. Several advantages of utilizing cat states in noncommutative space over the standard quantum mechanical spaces have been reported here. For instance, the q -deformed parameter has been utilized to improve the squeezing of the quadrature beyond the ordinary case. Most importantly, the parameter provides an extra degree of freedom by which we achieve both quadrature squeezed and number squeezed cat states at the same time in a single system, which is impossible to achieve from ordinary cat states.

  4. High strain rate deformation of layered nanocomposites.

    PubMed

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A; Thomas, Edwin L

    2012-01-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  5. High strain rate deformation of layered nanocomposites

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

    2012-11-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  6. Interpretation of microstructures in high temperature deformation

    SciTech Connect

    McQueen, H.J.

    1999-07-01

    In each historical period the microstructures produced by high temperature straining were probed by the current technology, this giving rise to new models and theories of rate controlling mechanisms. The progress in understanding has not been monotonic since occasionally theories were developed to high levels of sophistication while overlooking aspects of the substructure which were to become significant. New technologies such as TEM, or SEM-EBSP-OIM have made possible great leaps forward but often leave unresolved problems on a different scale. Experimental observations are presented of substructures in Al with solute, dynamic precipitates, dispersoids and reinforcing particles and in both austenitic and ferritic stainless steels, thus providing a range of crystal structures and stacking fault energies (SFE). After the historical analysis, the current view of the hot-worked state will be presented with comparison of the conflicting theories. The analysis is centered on dislocation strain and there is only mention of pertinent interactions with grain boundary related deformation. The first seventy references point to research being done during the period that Prof. Julia Weertman (also the author) was pursuing research for the Ph.D. or starting a teaching career. it was an exciting time in which the applications of dislocation theory to cold working, recovery and creep were being confirmed by intragranular structural observations. Both the new modes of microscopic examination and the enhanced theories made possible the surge in fundamental understanding of hot working mechanisms that were summarized in the following twenty classic reviews. Finally, the remaining fifty references survey the current research which attempts to clarify the more complex details of the mechanisms: dynamic recovery (DRV) and dynamic recrystallization (DRX).

  7. Block versus continuum deformation in the Western United States

    USGS Publications Warehouse

    King, G.; Oppenheimer, D.; Amelung, F.

    1994-01-01

    The relative role of block versus continuum deformation of continental lithosphere is a current subject of debate. Continuous deformation is suggested by distributed seismicity at continental plate margins and by cumulative seismic moment sums which yield slip estimates that are less than estimates from plate motion studies. In contrast, block models are favored by geologic studies of displacement in places like Asia. A problem in this debate is a lack of data from which unequivocal conclusions may be reached. In this paper we apply the techniques of study used in regions such as the Alpine-Himalayan belt to an area with a wealth of instrumental data-the Western United States. By comparing plate rates to seismic moment release rates and assuming a typical seismogenic layer thickness of 15 km it appears that since 1850 about 60% of the Pacific-North America motion across the plate boundary in California and Nevada has occurred seismically and 40% aseismically. The San Francisco Bay area shows similar partitioning between seismic and aseismic deformation, and it can be shown that within the seismogenic depth range aseismic deformation is concentrated near the surface and at depth. In some cases this deformation can be located on creeping surface faults, but elsewhere it is spread over a several kilometer wide zone adjacent to the fault. These superficial creeping deformation zones may be responsible for the palaeomagnetic rotations that have been ascribed elsewhere to the surface expression of continuum deformation in the lithosphere. Our results support the dominant role of non-continuum deformation processes with the implication that deformation localization by strain softening must occur in the lower crust and probably the upper mantle. Our conclusions apply only to the regions where the data are good, and even within the Western United States (i.e., the Basin and Range) deformation styles remain poorly resolved. Nonetheless, we maintain that block motion is the

  8. High-Temperature Deformation of Enstatite Aggregates

    NASA Astrophysics Data System (ADS)

    Bystricky, M.; Lawlis, J.; Mackwell, S. J.; Heidelbach, F.; Raterron, P. C.

    2011-12-01

    Although enstatite is a significant component of the upper mantle, its rheology is still poorly understood. We have performed an experimental investigation of the mechanical properties of enstatite at high pressure and temperature in the proto- and ortho-enstatite stability fields. Synthetic enstatite powders were produced by reacting San Carlos olivine powders with lab-grade quartz. Powders were hot-pressed at high PT, and were then baked at 1000°C under controlled oxygen fugacity conditions to remove all hydrous defect species. The polycrystalline enstatite samples were deformed in a Paterson gas-medium apparatus at temperatures of 1200-1300°C, an oxygen fugacity buffered at Ni/NiO, and confining pressures of 300 or 450 MPa. Under these conditions, samples were in the orthoenstatite field at 450 MPa and likely mainly in the protoenstatite field at 300 MPa. At both confining pressures, the mechanical data display a progressive increase of the stress exponent n from 1 to 3 as a function of differential stress, suggesting a transition from diffusional to dislocation creep. Non-linear least-square fits to the high-stress data yielded flow laws with n=3 and activation energies of 600 and 720 kJ/mol for ortho- and proto-enstatite, respectively. The measured strengths are significantly higher than those derived from Raleigh et al. (1971) and Ross and Nielsen (1978), due to the influence of water on the mechanical behavior of their samples. Deformed samples were analysed using optical microscopy, SEM and TEM. Because enstatite reverts to clinoenstatite during quenching, the microstructures present highly twinned grains composed of thin alternating domains of clino- and ortho-pyroxene. Nevertheless, the microstructures show evidence of dislocation processes in the form of undulatory extinction and kink bands. Crystallographic preferred orientations measured by EBSD are axisymmetric and indicate preferential slip on (100)[001]. High resolution TEM indicates that for

  9. Machining and grinding: High rate deformation in practice

    SciTech Connect

    Follansbee, P.S.

    1993-04-01

    Machining and grinding are well-established material-working operations involving highly non-uniform deformation and failure processes. A typical machining operation is characterized by uncertain boundary conditions (e.g.,surface interactions), three-dimensional stress states, large strains, high strain rates, non-uniform temperatures, highly localized deformations, and failure by both nominally ductile and brittle mechanisms. While machining and grinding are thought to be dominated by empiricism, even a cursory inspection leads one to the conclusion that this results more from necessity arising out of the complicated and highly interdisciplinary nature of the processes than from the lack thereof. With these conditions in mind, the purpose of this paper is to outline the current understanding of strain rate effects in metals.

  10. Machining and grinding: High rate deformation in practice

    SciTech Connect

    Follansbee, P.S.

    1993-01-01

    Machining and grinding are well-established material-working operations involving highly non-uniform deformation and failure processes. A typical machining operation is characterized by uncertain boundary conditions (e.g.,surface interactions), three-dimensional stress states, large strains, high strain rates, non-uniform temperatures, highly localized deformations, and failure by both nominally ductile and brittle mechanisms. While machining and grinding are thought to be dominated by empiricism, even a cursory inspection leads one to the conclusion that this results more from necessity arising out of the complicated and highly interdisciplinary nature of the processes than from the lack thereof. With these conditions in mind, the purpose of this paper is to outline the current understanding of strain rate effects in metals.

  11. Insect wing deformation measurements using high speed digital holographic interferometry.

    PubMed

    Aguayo, Daniel D; Mendoza Santoyo, Fernando; De la Torre-I, Manuel H; Salas-Araiza, Manuel D; Caloca-Mendez, Cristian; Gutierrez Hernandez, David Asael

    2010-03-15

    An out-of-plane digital holographic interferometry system is used to detect and measure insect's wing micro deformations. The in-vivo phenomenon of the flapping is registered using a high power cw laser and a high speed camera. A series of digital holograms with the deformation encoded are obtained. Full field deformation maps are presented for an eastern tiger swallowtail butterfly (Pterourus multicaudata). Results show no uniform or symmetrical deformations between wings. These deformations are in the order of hundreds of nanometers over the entire surface. Out-of-plane deformation maps are presented using the unwrapped phase maps.

  12. High stroke pixel for a deformable mirror

    DOEpatents

    Miles, Robin R.; Papavasiliou, Alexandros P.

    2005-09-20

    A mirror pixel that can be fabricated using standard MEMS methods for a deformable mirror. The pixel is electrostatically actuated and is capable of the high deflections needed for spaced-based mirror applications. In one embodiment, the mirror comprises three layers, a top or mirror layer, a middle layer which consists of flexures, and a comb drive layer, with the flexures of the middle layer attached to the mirror layer and to the comb drive layer. The comb drives are attached to a frame via spring flexures. A number of these mirror pixels can be used to construct a large mirror assembly. The actuator for the mirror pixel may be configured as a crenellated beam with one end fixedly secured, or configured as a scissor jack. The mirror pixels may be used in various applications requiring high stroke adaptive optics.

  13. Steady state and a general scale law of deformation

    NASA Astrophysics Data System (ADS)

    Huang, Yan

    2017-07-01

    Steady state deformation has been characterized based on the experimental results for dilute single-phase aluminium alloys. It was found that although characteristic properties such as flow stress and grain size remained constant with time, a continuous loss of grain boundaries occurred as an essential feature at steady state. A physical model, which takes into account the activity of grain boundary dislocations, was developed to describe the kinetics of steady state deformation. According to this model, the steady state as a function of strain rate and temperature defines the limit of the conventional grain size and strength relationship, i.e., the Hall-Petch relation holds when the grain size is larger than that at the steady state, and an inverse Hall-Petch relation takes over if grain size is smaller than the steady state value. The transition between the two relationships relating grain size and strength is a phenomenon that depends on deformation conditions, rather than an intrinsic property as generally perceived. A general scale law of deformation is established accordingly.

  14. Dynamic shear deformation in high purity Fe

    SciTech Connect

    Cerreta, Ellen K; Bingert, John F; Trujillo, Carl P; Lopez, Mike F; Gray, George T

    2009-01-01

    The forced shear test specimen, first developed by Meyer et al. [Meyer L. et al., Critical Adiabatic Shear Strength of Low Alloyed Steel Under Compressive Loading, Metallurgical Applications of Shock Wave and High Strain Rate Phenomena (Marcel Decker, 1986), 657; Hartmann K. et al., Metallurgical Effects on Impact Loaded Materials, Shock Waves and High Strain rate Phenomena in Metals (Plenum, 1981), 325-337.], has been utilized in a number of studies. While the geometry of this specimen does not allow for the microstructure to exactly define the location of shear band formation and the overall mechanical response of a specimen is highly sensitive to the geometry utilized, the forced shear specimen is useful for characterizing the influence of parameters such as strain rate, temperature, strain, and load on the microstructural evolution within a shear band. Additionally, many studies have utilized this geometry to advance the understanding of shear band development. In this study, by varying the geometry, specifically the ratio of the inner hole to the outer hat diameter, the dynamic shear localization response of high purity Fe was examined. Post mortem characterization was performed to quantify the width of the localizations and examine the microstructural and textural evolution of shear deformation in a bcc metal. Increased instability in mechanical response is strongly linked with development of enhanced intergranular misorientations, high angle boundaries, and classical shear textures characterized through orientation distribution functions.

  15. Localization in Naturally Deformed Systems - the Default State?

    NASA Astrophysics Data System (ADS)

    Clancy White, Joseph

    2017-04-01

    Based on the extensive literature on localized rock deformation, conventional wisdom would interpret it to be a special behaviour within an anticipated background of otherwise uniform deformation. The latter notwithstanding, the rock record is so rife with transient (cyclic), heterogeneous deformation, notably shear localization, as to characterize localization as the anticipated 'normal' behaviour. The corollary is that steady, homogeneous deformation is significantly less common, and if achieved must reflect some special set of conditions that are not representative of the general case. An issue central to natural deformation is then not the existance of localized strain, but rather how the extant deformation processes scale across tectonic phenomena and in turn organize to enable a coherent(?) descripion of Earth deformation. Deformation is fundamentally quantized, discrete (diffusion, glide, crack propagation) and reliant on the defect state of rock-forming minerals. The strain energy distribution that drives thermo-mechanical responses is in the first instance established at the grain-scale where the non-linear interaction of defect-mediated micromechanical processes introduces heterogeneous behaviour described by various gradient theories, and evidenced by the defect microstructures of deformed rocks. Hence, the potential for non-uniform response is embedded within even quasi-uniform, monomineralic materials, seen, for example, in the spatially discrete evolution of dynamic recrystallization. What passes as homogeneous or uniform deformation at various scales is the aggregation of responses at some characteristic dimension at which heterogeneity is not registered or measured. Nevertheless, the aggregate response and associated normalized parameters (strain, strain rate) do not correspond to any condition actually experienced by the deforming material. The more common types of macroscopic heterogeneity promoting localization comprise mechanically contrasting

  16. Deformation across the western United States: A local estimate of Pacific-North America transform deformation

    NASA Technical Reports Server (NTRS)

    Humphreys, Eugene D.; Weldon, Ray J., II

    1994-01-01

    We obtain a locally based estimate of Pacific-North America relative motion and an uncertainly in this estimate by integrating deformation rate along three different paths leading west across southwestern North America from east of the Rio Grande Rift to near the continental escarpment. Data are primarily Quatenary geologic slip rates estimates, and resulting deformation determinations therefore are 'instantaneous' in a geologic sense but 'long term' with respect to earthquake cycles. We deduce a rate of motion of the Pacific plane relative to North America that is 48 +/- 2 mm/yr, a rate indistinguishable from that predicted by the global kinematics models RM2 and NUVEL-1; however, we obtain an orientation that is 5-9 deg counterclockwise of these models. A more westerly motion of the Pacific plate, with respect to North America, is calculated from all three paths. The relatively westerly motion of the Pacific plate is accomodated by deformation in the North American continent that includes slip on relatively counterclockwise-oriented strike-slip faults (including the San Andreas fault), whic is especially relevant in and south of the Transverse Ranges, and a margin-normal component of net extension across the continent, which is especially relevant north of the Transverse Ranges. Deformation of the SW United States occurs in regionally coherent domains within the style of deformation is approximately uniform.

  17. Elastoplastic behavior of copper upon high-strain-rate deformation

    NASA Astrophysics Data System (ADS)

    Chembarisova, R. G.

    2015-06-01

    The deformation behavior of copper under conditions of high-strain-rate deformation has been investigated based on the model of elastoplastic medium with allowance for the kinetics of plastic deformation. Data have been obtained on the evolution of the dislocation subsystem, namely, on the average dislocation density, density of mobile dislocations, velocity of dislocation slip, concentration of deformation-induced vacancies, and density of twins. The coefficient of the annihilation of screw dislocations has been estimated depending on pressure and temperature. It has been shown that severe shear stresses that arise upon high-strain-rate deformation can lead to a significant increase in the concentration of vacancies. The time of the dislocation annihilation upon their nonconservative motion has been estimated. It has been shown that this time is much greater than the time of the deformation process in the samples, which makes it possible to exclude the annihilation of dislocations upon their nonconservative motion from the active mechanisms of deformation.

  18. The use of ion beam cleaning to obtain high quality cold welds with minimal deformation

    NASA Technical Reports Server (NTRS)

    Sater, B. L.; Moore, T. J.

    1978-01-01

    A variation of cold welding is described which utilizes an ion beam to clean mating surfaces prior to joining in a vacuum environment. High quality solid state welds were produced with minimal deformation.

  19. Biaxial deformation in high purity aluminum

    DOE PAGES

    Livescu, V.; Bingert, J. F.; Liu, C.; ...

    2015-09-25

    The convergence of multiple characterization tools has been applied to investigate the relationship of microstructure on damage evolution in high purity aluminum. The extremely coarse grain size of the disc-shaped sample provided a quasi-two dimensional structure from which the location of surface-measured features could be inferred. In particular, the role of pre-existing defects on damage growth was accessible due to the presence of casting porosity in the aluminum. Micro tomography, electron backscatter diffraction, and digital image correlation were applied to interrogate the sample in three dimensions. Recently micro-bulge testing apparatus was used to deform the pre-characterized disc of aluminum inmore » biaxial tension, and related analysis techniques were applied to map local strain fields. Subsequent post-mortem characterization of the failed sample was performed to correlate structure to damaged regions. We determined that strain localization and associated damage was most strongly correlated with grain boundary intersections and plastic anisotropy gradients between grains. Pre-existing voids played less of an apparent role than was perhaps initially expected. Finally, these combined techniques provide insight to the mechanism of damage initiation, propagation, and failure, along with a test bed for predictive damage models incorporating anisotropic microstructural effects.« less

  20. Biaxial deformation in high purity aluminum

    SciTech Connect

    Livescu, V.; Bingert, J. F.; Liu, C.; Lovato, M. L.; Patterson, B. M.

    2015-09-25

    The convergence of multiple characterization tools has been applied to investigate the relationship of microstructure on damage evolution in high purity aluminum. The extremely coarse grain size of the disc-shaped sample provided a quasi-two dimensional structure from which the location of surface-measured features could be inferred. In particular, the role of pre-existing defects on damage growth was accessible due to the presence of casting porosity in the aluminum. Micro tomography, electron backscatter diffraction, and digital image correlation were applied to interrogate the sample in three dimensions. Recently micro-bulge testing apparatus was used to deform the pre-characterized disc of aluminum in biaxial tension, and related analysis techniques were applied to map local strain fields. Subsequent post-mortem characterization of the failed sample was performed to correlate structure to damaged regions. We determined that strain localization and associated damage was most strongly correlated with grain boundary intersections and plastic anisotropy gradients between grains. Pre-existing voids played less of an apparent role than was perhaps initially expected. Finally, these combined techniques provide insight to the mechanism of damage initiation, propagation, and failure, along with a test bed for predictive damage models incorporating anisotropic microstructural effects.

  1. Use of solid-state nanopores for sensing co-translocational deformation of nano-liposomes.

    PubMed

    Goyal, Gaurav; Darvish, Armin; Kim, Min Jun

    2015-07-21

    Membrane deformation of nano-vesicles is crucial in many cellular processes such as virus entry into the host cell, membrane fusion, and endo- and exocytosis; however, studying the deformation of sub-100 nm soft vesicles is very challenging using the conventional techniques. In this paper, we report detecting co-translocational deformation of individual 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) nano-liposomes using solid-state nanopores. Electrokinetic translocation through the nanopore caused the soft DOPC liposomes (85 nm diameter) to change their shape, which we attribute to the strong electric field strength and physical confinement inside the pore. The experiments were performed at varying transmembrane voltages and the deformation was observed to mount up with increasing applied voltage and followed an exponential trend. Numerical simulations were performed to simulate the concentrated electric field strength inside the nanopore and a field strength of 14 kV cm(-1) (at 600 mV applied voltage) was achieved at the pore center. The electric field strength inside the nanopore is much higher than the field strength known to cause deformation of 15-30 μm giant membrane vesicles. As a control, we also performed experiments with rigid polystyrene beads that did not show any deformation during translocation events, which further established our hypothesis of co-translocational deformation of liposomes. Our technique presents an innovative and high throughput means for investigating deformation behavior of soft nano-vesicles.

  2. Measuring High Speed Deformation for Space Applications

    NASA Technical Reports Server (NTRS)

    Wentzel, Daniel

    2014-01-01

    PDV (Photonic Doppler Velocimetry) has proven to be a reliable and versatile technique to observe rapid deformation of frangible joints. It will be a valuable technique in order to understand the physics of two-stage light gas guns and the material response to hypervelocity impact.

  3. Effect of Purity Levels on the High-Temperature Deformation Characteristics of Severely Deformed Titanium

    NASA Astrophysics Data System (ADS)

    Sajadifar, Seyed Vahid; Yapici, Guney Guven

    2017-01-01

    In the present investigation, high-temperature compression tests were conducted at strain rates of 0.001 to 0.1 s-1 and at temperatures of 873 K to 1173 K (600 °C to 900 °C) in order to study the hot deformation characteristics and dynamic softening mechanisms of two different grades of commercial purity titanium after severe plastic deformation. It was observed that the effects of deformation rate and temperature are significant on obtained flow stress curves of both grades. Higher compressive strength exhibited by grade 2 titanium at relatively lower deformation temperatures was attributed to the grain boundary characteristics in relation with its lower processing temperature. However, severely deformed grade 4 titanium demonstrated higher compressive strength at relatively higher deformation temperatures (above 800 °C) due to suppressed grain growth via oxygen segregation limiting grain boundary motion. Constitutive equations were established to model the flow behavior, and the validity of the predictions was demonstrated with decent agreement accompanied by average error levels less than 5 pct for all the deformation conditions.

  4. Effect of Purity Levels on the High-Temperature Deformation Characteristics of Severely Deformed Titanium

    NASA Astrophysics Data System (ADS)

    Sajadifar, Seyed Vahid; Yapici, Guney Guven

    2017-03-01

    In the present investigation, high-temperature compression tests were conducted at strain rates of 0.001 to 0.1 s-1 and at temperatures of 873 K to 1173 K (600 °C to 900 °C) in order to study the hot deformation characteristics and dynamic softening mechanisms of two different grades of commercial purity titanium after severe plastic deformation. It was observed that the effects of deformation rate and temperature are significant on obtained flow stress curves of both grades. Higher compressive strength exhibited by grade 2 titanium at relatively lower deformation temperatures was attributed to the grain boundary characteristics in relation with its lower processing temperature. However, severely deformed grade 4 titanium demonstrated higher compressive strength at relatively higher deformation temperatures (above 800 °C) due to suppressed grain growth via oxygen segregation limiting grain boundary motion. Constitutive equations were established to model the flow behavior, and the validity of the predictions was demonstrated with decent agreement accompanied by average error levels less than 5 pct for all the deformation conditions.

  5. Modelling highly deformable metal extrusion using SPH

    NASA Astrophysics Data System (ADS)

    Prakash, Mahesh; Cleary, Paul W.

    2015-05-01

    Computational modelling is often used to reduce trial extrusions through accurate defect prediction. Traditionally, metal extrusion is modelled using mesh based finite element methods. However, large plastic deformations can lead to heavy re-meshing and numerical diffusion. Here we use the mesh-less smoothed particle hydrodynamics method since it allows simulation of large deformations without re-meshing and the tracking of history dependent properties such as plastic strain making it suitable for defect prediction. The variation in plastic strain and deformation for aluminium alloy in a cylindrical 3D geometry with extrusion ratio and die angle is evaluated. The extrusion process is found to have three distinct phases consisting of an initial sharp rise in extrusion force, a steady phase requiring constant force and terminating in a sharp decline in force as metal is completely extruded. Deformation and plastic strain increased significantly with extrusion ratio but only moderately with die angle. Extrusion force increased by 150 % as the extrusion ratio increased from 2:1 to 4:1 but had only a marginal change with die angle. A low strain zone in the centre of the extruded product was found to be a function of extrusion ratio but was persistent and did not vary with die angle. Simulation of a complex 3D building industry component showed large variations in plastic strain along the length of the product at two scales. These were due to change in metal behaviour as extrusion progressed from phase 1 to phase 2. A stagnation zone at the back of the die was predicted that could lead to the "funnel" or "pipe" defect.

  6. Highly Deformable Origami Paper Photodetector Arrays.

    PubMed

    Lin, Chun-Ho; Tsai, Dung-Sheng; Wei, Tzu-Chiao; Lien, Der-Hsien; Ke, Jr-Jian; Su, Chun-Hao; Sun, Ju-Yen; Liao, Ying-Chih; He, Jr-Hau

    2017-09-27

    Flexible electronics will form the basis of many next-generation technologies, such as wearable devices, biomedical sensors, the Internet of things, and more. However, most flexible devices can bear strains of less than 300% as a result of stretching. In this work, we demonstrate a simple and low-cost paper-based photodetector array featuring superior deformability using printable ZnO nanowires, carbon electrodes, and origami-based techniques. With a folded Miura structure, the paper photodetector array can be oriented in four different directions via tessellated parallelograms to provide the device with excellent omnidirectional light harvesting capabilities. Additionally, we demonstrate that the device can be repeatedly stretched (up to 1000% strain), bent (bending angle ±30°), and twisted (up to 360°) without degrading performance as a result of the paper folding technique, which enables the ZnO nanowire layers to remain rigid even as the device is deformed. The origami-based strategy described herein suggests avenues for the development of next-generation deformable optoelectronic applications.

  7. Continuous deformation versus episodic deformation at high stress - the microstructural record

    NASA Astrophysics Data System (ADS)

    Trepmann, C. A.; Stöckhert, B.

    2009-04-01

    The microstructural record of continuous high stress deformation is compared to that of episodic high stress deformation on two examples: 1. Folding of quartz veins in metagreywacke from Pacheco Pass, California, undergoing deformation by dissolution precipitation creep at temperatures of 300 ± 50°C. The microfabric of the folded quartz veins indicates deformation by dislocation creep accompanied by subgrain rotation. The small recrystallized grain size of ~8±6 µm in average implies relatively high differential stresses of a few hundred MPa. The stress concentration in the vein is due to a high contrast in effective viscosities between the single phase material and the polyphase fine-grained host metagreywacke deforming by dissolution precipitation creep. Smoothly curved, but generally not sutured, grain boundaries as well as the small size and a relatively high dislocation density of recrystallized grains suggest that strain-induced grain boundary migration was of minor importance. This is suspected to be a consequence of low strain gradients, which are due to the relative rates of dynamic recovery and continuous dislocation production during climb-controlled creep, at high stress and the given low temperature. Subgrain rotation recrystallization is thus proposed to be characteristic for continuous deformation at high differential stress. 2. Episodic deformation in the middle crust at the tip of a seismic active fault zone. The microfabric of mid-crustal rocks exhumed in tectonically active regions can record episodic high stress deformation at the base of the seismogenic layer. The quartz veins from St. Paul la Roche in the Massif Central, France, are very coarse grained. On the scale of a thin section they are basically single crystalline. However, they show a very heterogeneous microstructure with a system of healed microcracks that are decorated by subgrains and more rarely by small recrystallized grains. Undulating deformation lamellae that do not show a

  8. Phenomenological model for transient deformation based on state variables

    SciTech Connect

    Jackson, M S; Cho, C W; Alexopoulos, P; Mughrabi, H; Li, C Y

    1980-01-01

    The state variable theory of Hart, while providing a unified description of plasticity-dominated deformation, exhibits deficiencies when it is applied to transient deformation phenomena at stresses below yield. It appears that the description of stored anelastic strain is oversimplified. Consideration of a simple physical picture based on continuum dislocation pileups suggests that the neglect of weak barriers to dislocation motion is the source of these inadequacies. An appropriately modified description incorporating such barriers then allows the construction of a macroscopic model including transient effects. Although the flow relations for the microplastic element required in the new theory are not known, tentative assignments may be made for such functions. The model then exhibits qualitatively correct behavior when tensile, loading-unloading, reverse loading, and load relaxation tests are simulated. Experimental procedures are described for determining the unknown parameters and functions in the new model.

  9. BPS states in the duality web of the Omega deformation

    NASA Astrophysics Data System (ADS)

    Hellerman, Simeon; Orlando, Domenico; Reffert, Susanne

    2013-06-01

    In this note, we study different limits of an Ω-deformed (2, 0) six-dimensional gauge theory realized in an M-theory fluxtrap background. Via a chain of dualities, we connect the Ω-deformed sym to a new four-dimensional gauge theory which we refer to as the reciprocal gauge theory. This theory has several properties in common with Liouville field theory, such as its gauge coupling b 2 = ɛ 2/ ɛ 1, and its behavior under S-duality. Finally, we realize the bps states on the sym side of the agt correspondence and follow them along the chain of dualities. In the fluxtrap frame, we are dealing with two distinct types of states localized in different radial positions, while in the reciprocal frame, we find single states carrying both charges localized in one place which appear to be perturbatively stable. Our microscopic picture of the small- b limit exhibits semiclassically bps bound states, which are not visible at the level of the partition function.

  10. Deformation Twinning of a Silver Nanocrystal under High Pressure

    SciTech Connect

    Huang, Xiaojing; Yang, Wenge; Harder, Ross; Sun, Yugang; Liu, Ming; Chu, Yong S.; Robinson, Ian K.; Mao, Ho-kwang

    2015-11-01

    Within a high-pressure environment, crystal deformation is controlled by complex processes such as dislocation motion, twinning, and phase transitions, which change materials' microscopic morphology and alter their properties. Understanding a crystal's response to external stress provides a unique opportunity for rational tailoring of its functionalities. It is very challenging to track the strain evolution and physical deformation from a single nanoscale crystal under high-pressure stress. Here, we report an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube within a high-pressure environment using the Bragg Coherent Diffractive Imaging (CDI) method. We observed a continuous lattice distortion, followed by a deformation twining process at a constant pressure. The ability to visualize stress-introduced deformation of nanocrystals with high spatial resolution and prominent strain sensitivity provides an important route for interpreting and engineering novel properties of nanomaterials.

  11. Deformation Twinning of a Silver Nanocrystal under High Pressure

    SciTech Connect

    Huang, Xiaojing; Yang, Wenge; Harder, Ross; Sun, Yugang; Lu, Ming; Chu, Yong S.; Robinson, Ian K.; Mao, Ho-kwang

    2015-10-20

    Within a high-pressure environment, crystal deformation is controlled by complex processes such as dislocation motion, twinning, and phase transitions, which change materials’ microscopic morphology and alter their properties. Understanding a crystal’s response to external stress provides a unique opportunity for rational tailoring of its functionalities. It is very challenging to track the strain evolution and physical deformation from a single nanoscale crystal under high-pressure stress. Here, we report an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube within a high-pressure environment using the Bragg Coherent Diffractive Imaging (CDI) method. We observed a continuous lattice distortion, followed by a deformation twining process at a constant pressure. The ability to visualize stress-introduced deformation of nanocrystals with high spatial resolution and prominent strain sensitivity provides an important route for interpreting and engineering novel properties of nanomaterials.

  12. Dislocation models of interseismic deformation in the western United States

    USGS Publications Warehouse

    Pollitz, F.F.; McCrory, P.; Svarc, J.; Murray, J.

    2008-01-01

    The GPS-derived crustal velocity field of the western United States is used to construct dislocation models in a viscoelastic medium of interseismic crustal deformation. The interseismic velocity field is constrained by 1052 GPS velocity vectors spanning the ???2500-km-long plate boundary zone adjacent to the San Andreas fault and Cascadia subduction zone and extending ???1000 km into the plate interior. The GPS data set is compiled from U.S. Geological Survey campaign data, Plate Boundary Observatory data, and the Western U.S. Cordillera velocity field of Bennett et al. (1999). In the context of viscoelastic cycle models of postearthquake deformation, the interseismic velocity field is modeled with a combination of earthquake sources on ???100 known faults plus broadly distributed sources. Models that best explain the observed interseismic velocity field include the contributions of viscoelastic relaxation from faulting near the major plate margins, viscoelastic relaxation from distributed faulting in the plate interior, as well as lateral variations in depth-averaged rigidity in the elastic lithosphere. Resulting rigidity variations are consistent with reduced effective elastic plate thickness in a zone a few tens of kilometers wide surrounding the San Andreas fault (SAF) system. Primary deformation characteristics are captured along the entire SAF system, Eastern California Shear Zone, Walker Lane, the Mendocino triple junction, the Cascadia margin, and the plate interior up to ???1000 km from the major plate boundaries.

  13. Deformed band structures at high spin in 200Tl

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Soumik; Bhattacharyya, S.; Das Gupta, S.; Pai, H.; Mukherjee, G.; Palit, R.; Xu, F. R.; Wu, Q.; Shrivastava, A.; Asgar, Md. A.; Banik, R.; Bhattacharjee, T.; Chanda, S.; Chatterjee, A.; Goswami, A.; Nanal, V.; Pandit, S. K.; Saha, S.; Sethi, J.; Roy, T.; Thakur, S.

    2017-01-01

    High-spin band structures of 200Tl have been studied by γ -ray spectroscopic methods using the 198Pt(7Li,5 n )200Tl reaction at 45 MeV of beam energy. The level scheme of 200Tl has been extended significantly and several new band structures have been established with the observation of 60 new transitions. The π h9 /2⊗ν i13 /2 oblate band has been extended beyond the particle alignment frequencies. The band structures and the other excited states have been compared with the neighboring odd-odd Tl isotopes. Total Routhian surface calculations have been performed to study the deformation and shape changes as a function of spin in this nucleus. These calculations could reproduce the particle alignment frequency and suggest that the neutron pair alignment in ν i13 /2 orbital induces γ softness in 200Tl.

  14. Direct state reconstruction with coupling-deformed pointer observables

    NASA Astrophysics Data System (ADS)

    Zhu, Xuanmin; Zhang, Yu-Xiang; Wu, Shengjun

    2016-06-01

    Direct state tomography (DST) using weak measurements has received wide attention. Based on the concept of coupling-deformed pointer observables presented by Zhang et al. [Y.-X. Zhang, S. Wu, and Z.-B. Chen, Phys. Rev. A 93, 032128 (2016), 10.1103/PhysRevA.93.032128], a modified direct state tomography (MDST) is proposed, examined, and compared with other typical state tomography schemes. MDST has exact validity for measurements of any strength. We identify the strength needed to attain the highest efficiency level of MDST by using statistical theory. MDST is much more efficient than DST in the sense that far fewer samples are needed to reach DST's level of reconstruction accuracy. Moreover, MDST has no inherent bias when compared to DST.

  15. High-actuator-count MEMS deformable mirrors

    NASA Astrophysics Data System (ADS)

    Helmbrecht, Michael A.; He, Min; Kempf, Carl J.

    2013-05-01

    Adaptive optics (AO) technology has enabled dramatic improvement in imaging performance for fields spanning astronomy, defense, microscopy, and retinal imaging. A critical component within the AO systems is the deformable mirror (DM) that implements the actual wavefront correction. This paper introduces the Iris AO segmented MEMS DM technology with an overview of the fabrication process and a description of the DM operation. The paper demonstrates correction capabilities of 111 and 489 actuator DMs and describes recent effort for scaling to 1000-actuator class DMs. Finally, the paper presents laser testing results of dielectric coated DMs and describes the development path for MEMS DMs capable of 2.8 kW/cm2 average laser power.

  16. Plastic deformation and sintering of alumina under high pressure

    SciTech Connect

    Liu, Fangming; Liu, Pingping; Wang, Haikuo; Xu, Chao; Yin, Shuai; Yin, Wenwen; Li, Yong; He, Duanwei

    2013-12-21

    Plastic deformation of alumina (Al{sub 2}O{sub 3}) under high pressure was investigated by observing the shape changes of spherical particles, and the near fully dense transparent bulks were prepared at around 5.5 GPa and 900 °C. Through analyzing the deformation features, densities, and residual micro-strain of the Al{sub 2}O{sub 3} compacts prepared under high pressures and temperatures (2.0–5.5 GPa and 600–1200 °C), the effects of plastic deformation on the sintering behavior of alumina have been demonstrated. Under compression, the microscopic deviatoric stress caused by grain-to-grain contact could initiate the plastic deformation of individual particles, eliminate pores of the polycrystalline samples, and enhance the local atomic diffusion at the grain boundaries, thus produced transparent alumina bulks.

  17. Simulation of erythrocyte deformation in a high shear flow.

    PubMed

    Nakamura, Masanori; Bessho, Sadao; Wada, Shigeo

    2009-01-01

    Deformation of a red blood cell (RBC) in a high-shear flow was investigated. The RBC was modeled as a closed shell membrane consisting of spring networks in the framework of the energy minimum concept. The simulation of RBC in a parallel shear flow showed deformation parameters of RBC were well agreed with experimental results. The simulation of RBC behavior in various flow fields demonstrated that the shape was determined not only by instantaneous fluid force acting on it but also its deformation history. No consistency was found between the maximum of the first principal strain and conventionally used hemolysis index. Those results addressed the importance of considering an RBC deformation for accurately predicting hemolysis.

  18. Novel high-bandwidth bimorph deformable mirrors

    NASA Astrophysics Data System (ADS)

    Griffith, Michael S.; Laycock, Leslie C.; Archer, Nick J.

    2004-12-01

    Adaptive Optics (AO) is a critical underpinning technology for future laser delivery (including free-space optical communications), target illumination and imaging systems. It measures and compensates for optical distortion caused by transmission through the atmosphere, resulting in the ability to deploy smaller lasers and identify targets at greater ranges. One of the key components in an AO system is the wavefront modifier, which acts on the incoming or outgoing beam to counter the effects of the atmosphere. BAE SYSTEMS Advanced Technology Centre is developing multi-element bimorph deformable mirrors for such an applications. Our initial designs were based on a standard construction and exhibited a resonant frequency of 1kHz with a maximum stroke of +/-20μm for an active aperture of 50mm. These devices were limited by the necessity to have a 'dead space' between the inner active area and the mirror boundary; this ensured that both the requirements for the stroke and the fixed boundary conditions could be met simultaneously. However, there was a significant penalty to pay in terms of bandwidth, which is inversely proportional to the square of the full mirror diameter. In a series of iteration steps, we have created novel mounting arrangements that reduce dead space and thus provide the optimum trade-off between bandwidth and stroke. These schemes include supporting the mirror from underneath, rather than at its edge. As a result, models of 60mm active diameter mirrors predict a resonance in excess of 5kHz, combined with a maximum stroke greater than +/-40μm. This paper will discuss a number of different mirror designs and present experimental results for recently assembled devices.

  19. Calculation of the spectrum of {gamma} rays connecting superdeformed and normally deformed nuclear states

    SciTech Connect

    Dossing, T.; Khoo, T.L.; Lauritsen, T.

    1995-08-01

    The decay out of superdeformed states occurs by coupling to compound nuclear states of normal deformation. The coupling is very weak, resulting in mixing of the SD state with one or two normal compound states. With a high energy available for decay, a statistical spectrum ensues. The shape of this statistical spectrum contains information on the level densities of the excited states below the SD level. The level densities are sensitively affected by the pair correlations. Thus decay-out of a SD state (which presents us with a means to start a statistical cascade from a highly-excited sharp state) provides a method for investigating the reduction of pairing with increasing thermal excitation energy.

  20. High Resolution, Large Deformation 3D Traction Force Microscopy

    PubMed Central

    López-Fagundo, Cristina; Reichner, Jonathan; Hoffman-Kim, Diane; Franck, Christian

    2014-01-01

    Traction Force Microscopy (TFM) is a powerful approach for quantifying cell-material interactions that over the last two decades has contributed significantly to our understanding of cellular mechanosensing and mechanotransduction. In addition, recent advances in three-dimensional (3D) imaging and traction force analysis (3D TFM) have highlighted the significance of the third dimension in influencing various cellular processes. Yet irrespective of dimensionality, almost all TFM approaches have relied on a linear elastic theory framework to calculate cell surface tractions. Here we present a new high resolution 3D TFM algorithm which utilizes a large deformation formulation to quantify cellular displacement fields with unprecedented resolution. The results feature some of the first experimental evidence that cells are indeed capable of exerting large material deformations, which require the formulation of a new theoretical TFM framework to accurately calculate the traction forces. Based on our previous 3D TFM technique, we reformulate our approach to accurately account for large material deformation and quantitatively contrast and compare both linear and large deformation frameworks as a function of the applied cell deformation. Particular attention is paid in estimating the accuracy penalty associated with utilizing a traditional linear elastic approach in the presence of large deformation gradients. PMID:24740435

  1. High resolution, large deformation 3D traction force microscopy.

    PubMed

    Toyjanova, Jennet; Bar-Kochba, Eyal; López-Fagundo, Cristina; Reichner, Jonathan; Hoffman-Kim, Diane; Franck, Christian

    2014-01-01

    Traction Force Microscopy (TFM) is a powerful approach for quantifying cell-material interactions that over the last two decades has contributed significantly to our understanding of cellular mechanosensing and mechanotransduction. In addition, recent advances in three-dimensional (3D) imaging and traction force analysis (3D TFM) have highlighted the significance of the third dimension in influencing various cellular processes. Yet irrespective of dimensionality, almost all TFM approaches have relied on a linear elastic theory framework to calculate cell surface tractions. Here we present a new high resolution 3D TFM algorithm which utilizes a large deformation formulation to quantify cellular displacement fields with unprecedented resolution. The results feature some of the first experimental evidence that cells are indeed capable of exerting large material deformations, which require the formulation of a new theoretical TFM framework to accurately calculate the traction forces. Based on our previous 3D TFM technique, we reformulate our approach to accurately account for large material deformation and quantitatively contrast and compare both linear and large deformation frameworks as a function of the applied cell deformation. Particular attention is paid in estimating the accuracy penalty associated with utilizing a traditional linear elastic approach in the presence of large deformation gradients.

  2. Deformation processing of high-Tc superconducting oxides

    NASA Astrophysics Data System (ADS)

    Rajan, K.; German, R. M.; Knorr, D. B.; Maccrone, R. K.; Misiolek, W.; Wright, R. N.

    1989-04-01

    Plastic deformation and texture development in polycrystalline YBa2Cu3O7- δ has been studied to expedite the process development of high-critical-temperature (high-Tc) superconducting wires and tapes. It is anticipated that deformation texture will be a major processing consideration in terms of maximizing critical current density, assessing conductor-fabrication options in light of critical current density, and developing such mechanical properties as strength, toughness and thermal fatigue. The intrinsic texture development in YBa2Cu3O7- δ deformation processing should be highly beneficial, insofar as the c axes of the crystals tend to become oriented along the compression axis. This means that conducting tapes and wires formed by rolling, extrusion and drawing can develop textures with the c axis in the transverse or radial direction, thus maximizing the flow of current along the length of the conductor.

  3. A High-accuracy Micro-deformation Measurement Method

    NASA Astrophysics Data System (ADS)

    Jiang, Li

    2016-07-01

    The requirement for ever-increasing-resolution space cameras drives focal length and diameter of optical lenses be increasing. High-frequency vibration in the process of launching and complex environmental conditions of the outer space generate micro deformation in components of space cameras. As a result, images from the space cameras are blurred. Therefore, it is necessary to measure the micro deformations in components of space cameras in various experiment conditions. This paper presents a high-accuracy micro deformation measurement method. The method is implemented as follows: (1) fix Tungsten-steel balls onto a space camera being measured and measure the coordinate for each ball under the standard condition; (2) simulate high-frequency vibrations and environmental conditions like the outer space to measure coordinates for each ball under each combination of test conditions; and (3) compute the deviation of a coordinate of a ball under a test condition combination from the coordinate of the ball under the standard condition and the deviation is the micro deformation of the space camera component associated with the ball. This method was applied to micro deformation measurement for space cameras of different models. Measurement data for these space cameras validated the proposed method.

  4. Nanostructural states in Nb-Al mechanocomposite after combined deformation treatment

    SciTech Connect

    Ditenberg, Ivan A. Denisov, Konstantin I.; Tyumentsev, Alexander N.; Korchagin, Michail A.; Korznikov, Alexander V.

    2015-10-27

    Nanostructural states were investigated, that were formed in Nb-Al system-based mechanocomposite after combined deformation treatment that includes mechanical activation in a planetary ball mill and subsequent consolidation by torsion under pressure on Bridgman anvils. The formation of the layered structure, consisting of Nb and Al nanobands with width from several to several tens of nanometers was revealed. The structural states with high elastic curvature of crystal lattice and high level of local internal stresses found in Nb and Al subgrains were investigated by transmission electron microscopy.

  5. High-temperature behavior of a deformed Fermi gas obeying interpolating statistics

    NASA Astrophysics Data System (ADS)

    Algin, Abdullah; Senay, Mustafa

    2012-04-01

    An outstanding idea originally introduced by Greenberg is to investigate whether there is equivalence between intermediate statistics, which may be different from anyonic statistics, and q-deformed particle algebra. Also, a model to be studied for addressing such an idea could possibly provide us some new consequences about the interactions of particles as well as their internal structures. Motivated mainly by this idea, in this work, we consider a q-deformed Fermi gas model whose statistical properties enable us to effectively study interpolating statistics. Starting with a generalized Fermi-Dirac distribution function, we derive several thermostatistical functions of a gas of these deformed fermions in the thermodynamical limit. We study the high-temperature behavior of the system by analyzing the effects of q deformation on the most important thermostatistical characteristics of the system such as the entropy, specific heat, and equation of state. It is shown that such a deformed fermion model in two and three spatial dimensions exhibits the interpolating statistics in a specific interval of the model deformation parameter 0 < q < 1. In particular, for two and three spatial dimensions, it is found from the behavior of the third virial coefficient of the model that the deformation parameter q interpolates completely between attractive and repulsive systems, including the free boson and fermion cases. From the results obtained in this work, we conclude that such a model could provide much physical insight into some interacting theories of fermions, and could be useful to further study the particle systems with intermediate statistics.

  6. High Resolution Rapid Revisits Insar Monitoring of Surface Deformation

    NASA Astrophysics Data System (ADS)

    Singhroy, V.; Li, J.; Charbonneau, F.

    2014-12-01

    Monitoring surface deformation on strategic energy and transportation corridors requires high resolution spatial and temporal InSAR images for mitigation and safety purposes. High resolution air photos, lidar and other satellite images are very useful in areas where the landslides can be fatal. Recently, radar interferometry (InSAR) techniques using more rapid revisit images from several radar satellites are increasingly being used in active deformation monitoring. The Canadian RADARSAT Constellation (RCM) is a three-satellite mission that will provide rapid revisits of four days interferometric (InSAR) capabilities that will be very useful for complex deformation monitoring. For instance, the monitoring of surface deformation due to permafrost activity, complex rock slide motion and steam assisted oil extraction will benefit from this new rapid revisit capability. This paper provide examples of how the high resolution (1-3 m) rapid revisit InSAR capabilities will improve our monitoring of surface deformation and provide insights in understanding triggering mechanisms. We analysed over a hundred high resolution InSAR images over a two year period on three geologically different sites with various configurations of topography, geomorphology, and geology conditions. We show from our analysis that the more frequent InSAR acquisitions are providing more information in understanding the rates of movement and failure process of permafrost triggered retrogressive thaw flows; the complex motion of an asymmetrical wedge failure of an active rock slide and the identification of over pressure zones related to oil extraction using steam injection. Keywords: High resolution, InSAR, rapid revisits, triggering mechanisms, oil extraction.

  7. Microfabric development in dunite during high stress deformation and subsequent recrystallization

    NASA Astrophysics Data System (ADS)

    Trepmann, Claudia; Druiventak, Anthony; Matysiak, Agnes; Renner, Jörg

    2010-05-01

    The microfabric development in dunite is analyzed in non-steady state deformation and annealing experiments, which are designed to simulate earthquake-driven episodic creep in the upper mantle of the oceanic lithosphere at the base of the seismogenic zone. The samples are deformed in a servohydraulically-controlled solid medium deformation apparatus at a temperature of 600°C, a constant strain rate of 10-4s-1 (kick) and a confining pressure of 1.0 GPa. In some experiments deformation is followed by annealing for 15 h to 70 h at zero nominal differential stress, temperatures of 800°C to 1000°C (kick & cook) and 2.0 GPa confining pressure. We use coarse-grained dunite from the Almklovdalen peridotite complex (Western Norway) as starting material. The dunite comprises ca. 90% olivine, <10% orthopyroxene and small amounts of spinel and chlorite. The kick experiments yield maximum differential stress of ca. 1 GPa and < 20% of permanent strain. The resulting microfabrics are analysed by optical and electron microscopic techniques. Intragranular microcracks and micro-shear zones in olivine, which can be crystallographically controlled, developed during deformation. After annealing at 1000°C, the microfabric is characterized by very fine-grained recrystallized olivine grains with an average diameter of ca. 5 µm. The recrystallized grains are arranged along micro-shear zones and occur in aggregates surrounding olivine porphyroclasts. The area fraction of recrystallized grains is varying but generally smaller than 20%. The microfabrics from our experiments compare well with microfabrics observed from naturally deformed peridotites of the Baldissero, Balmuccia and Finero complexes in the Western Alps. Similar olivine recrystallization aggregates in naturally deformed peridotites are frequently interpreted as indicative of deformation by dislocation or diffusion creep. The microfabrics of our kick & cook experiments indicate a development through an initial stage of high

  8. Beam quality active control of a slab MOPA solid state laser with combined deformable mirrors

    NASA Astrophysics Data System (ADS)

    Xiang, Rujian; Xu, Honglai; Li, Guohui; Wu, Jing; Du, Yinglei; Zhang, Kai

    2017-01-01

    A novel phase aberration correcting method based on combined deformable mirrors (DMs) in a slab MOPA (master oscillator and power amplifier) solid state laser system is proposed and validated experimentally. The adaptive optics(AO) system with combined deformable mirrors composed of a one-dimension (1D) DM with 11 actuators and a two-dimension (2D) DM with 67 valid actuators, has been designed to correct the phase aberrations, which doesn't need the high voltage drivers and has an excellent correcting efficiency of the high order phase aberrations. The experimental results show that the wave front of the slab laser beam is compensated well and the residual wave front is less than 0.08 λ rms. The beam quality of the slab laser in the far field is improved to1.67x DL.

  9. HIGH-CONTRAST IMAGING VIA MODAL CONVERGENCE OF DEFORMABLE MIRROR

    SciTech Connect

    Wang Feiling

    2012-06-01

    For extremely high contrast imaging, such as direct observation of faint stellar companions, an adaptive optics system is required to produce low-halo and low-speckle regions in the focal plane. A method for deformable mirror control is proposed to achieve this goal. The method relies on a modal convergence of the deformable mirror driven by a focal-plane metric. The modal sets are derived from the Walsh functions. The Walsh-function modes serve two purposes: the expansion of the actuator displacements and the expansion of the phase functions. Taking advantage of the unique properties of the modal functions, a universal control algorithm is devised for the realization of high-contrast focal planes with and without the help of conventional coronagraphy. Numerical modeling is conducted to simulate complete imaging systems under various scenarios. It is shown that the proposed method reliably produces high-contrast focal planes using either a segmented or a membrane mirror. In the presence of random aberration the method is shown to be able to maintain high-contrast focal planes. Requiring neither retrieval of electric fields nor detailed knowledge of the deformable mirrors, this technique may allow high-contrast imaging in real time.

  10. Bone Ingrowth to Ti Fibre Knit Block with High Deformability

    PubMed Central

    Henmi, Yoko; Jimbo, Ryo; Jinno, Yohei; Sekine, Kazumitsu; Hamada, Kenichi

    2016-01-01

    ABSTRACT Objectives The objective of this study is to develop a Ti fibre knit block without sintering, and to evaluate its deformability and new bone formation in vivo. Material and Methods A Ti fibre with a diameter of 150 μm was knitted to fabricate a Ti mesh tube. The mesh tube was compressed in a metal mould to fabricate porous Ti fibre knit blocks with three different porosities of 88%, 69%, and 50%. The elastic modulus and deformability were evaluated using a compression test. The knit block was implanted into bone defects of a rabbit’s hind limb, and new bone formation was evaluated using micro computed tomography (micro-CT) analysis and histological analysis. Results The knit blocks with 88% porosity showed excellent deformability, indicating potential appropriateness for bone defect filling. Although the porosities of the knit block were different, they indicated similar elastic modulus smaller than 1 GPa. The elastic modulus after deformation increased linearly as the applied compression stress increased. The micro-CT analysis indicated that in the block with 50% porosity new bone filled nearly all of the pore volume four weeks after implantation. In contrast, in the block with 88% porosity, new bone filled less than half of the pore volume even 12 weeks after implantation. The histological analysis also indicated new bone formation in the block. Conclusions The titanium fibre knit block with high porosity is potentially appropriate for bone defect filling, indicating good bone ingrowth after porosity reduction with applied compression. PMID:28154746

  11. High-density deformable mirrors to enable coronographic planet detection

    NASA Astrophysics Data System (ADS)

    Ealey, Mark A.; Trauger, John T.

    2004-02-01

    Active wavefront correction of a space telescope provides a technology path for extremely high contrast imaging astronomy at levels well beyond the capabilities of current telescope systems. A precision deformable mirror technology intended specifically for wavefront correction in a visible/near-infrared space telescope has been developed at Xinetics and extensively tested at JPL over the past several years. Active wavefront phase correction has been demonstrated to 1-Angstrom rms over the spatial frequency range accessible to a mirror with an array of actuators on a 1-mm pitch. High density deformable mirror technology is based on a modular actuator arrays that are scalable to 1000s of actuator elements coupled to the surface of a thin mirror facesheet. Precision actuator control is done by using a low-power, vacuum compatible multiplexed driver system. Mirror surface figure, actuator influence function, and dimensional stability will be given in the context of the Eclipse point design for a coronagraphic space telescope.

  12. Effect of deformation on the structural state of piracetam

    NASA Astrophysics Data System (ADS)

    Kanunnikova, O. M.; Mikhailova, S. S.; Karban', O. V.; Mukhgalin, V. V.; Aksenova, V. V.; Sen'kovskii, B. V.; Pechina, E. A.; Lad'yanov, V. I.

    2016-04-01

    The effect of various deformation actions on the structure-phase transformations in piracetam of modifications I and II with a sodium acetate addition is studied. Mechanical activation and pressing are shown to cause the polymorphic transformation of modification I into modification II, and modification III forms predominantly during severe plastic deformation by torsion. The structural difference between the piracetam molecules of modifications I and II is found to be retained in aqueous solutions.

  13. Deformation of Single Crystal Molybdenum at High Pressure

    SciTech Connect

    Bonner, B P; Aracne, C; Farber, D L; Boro, C O; Lassila, D H

    2004-02-24

    Single crystal samples of micron dimensions oriented in the [001] direction were shortened 10 to 40% in uniaxial compression with superposed hydrostatic pressure to begin investigation of how the onset of yielding evolves with pressure. A testing machine based on opposed anvil geometry with precision pneumatic control of the applied force and capability to measure sub micron displacements was developed to produce shape changing deformation at pressure. The experiments extend observations of pressure dependent deformation to {approx}5Gpa at shortening rates of {approx}2*10{sup -4}. Samples have been recovered for post run characterization and analysis to determine if deformation mechanisms are altered by pressure. Experiments under hydrostatic pressure provide insight into the nature of materials under extreme conditions, and also provide a means for altering deformation behavior in a controlled fashion. The approach has a long history demonstrating that pressure enhances ductility in general, and produces enhanced hardening relative to that expected from normal cold work in the BCC metals Mo, Ta and Nb{sup 2}. The pressure hardening is in excess of that predicted from the measured increase in shear modulus at pressure, and therefore is likely due to a dislocation mechanism, such as suppression of kink pair formation or the interaction of forest dislocation cores, and not from lattice resistance. The effect has not been observed in FCC metals, suggesting a fundamental difference between deformation mechanisms at pressure for the two classes. The purpose of this letter is to investigate the origin of pressure hardening with new experiments that extend the pressure range beyond 3 GPa, the upper limit of conventional large sample (1cm{sup 3}) testing methods. Most previous high pressure deformation studies have been on poly crystals, relying on model dependent analysis to infer the maximum deviatoric stress that a deformed sample can support. In one experiment, a

  14. High strain rate deformation of martensitic NiTi shape memory alloy

    SciTech Connect

    Liu, Y.; Humbeeck, J. van; Li, Y.; Ramesh, K.T.

    1999-06-04

    Shape memory alloys possess three fundamental properties due to their unique deformation mechanisms: shape memory effect, superelasticity and high damping capacity. The first two properties have already shown significant prospects for application, while the third one has not attracted significant attention. Recently, however, these materials appear promising for civil engineering applications due to the high damping capacity, coupling with good strength, ductility and very good corrosion resistance. Previous research on the deformation behavior of SMAs has been focused on low strain rates. Recently, some preliminary results have been reported on stress-induced martensite formation with austenitic SMAs subjected to impact. However, the high strain rate deformation behavior of SMAs in their martensitic state has not been reported. In the present work, the mechanical behavior of a martensitic NiTi SMA under very high state rate (3 {times} 10{sup 3} s{sup {minus}1}) compression is obtained and is primarily compared to its low rate (3 {times} 10{sup {minus}4} s{sup {minus}1}) deformation behavior.

  15. Uniaxial plastic deformation of isotactic polypropylene studied by solid-state NMR

    NASA Astrophysics Data System (ADS)

    Kang, Jia

    At alleviated temperatures, some semicrystralline polymers can be stretched to very large deformation ratios. Such deformations of semicrystalline polymers have been extensively studied since 1960s. Based on experimental observations and theoretical investigations, solid-state transformation (three stage model) proposed in 1971 and local melting and recrystallization in 1978 have been considered two major mechanisms to explain the deformations of polymer crystals. With the elucidation of molecular dynamics in the last two decades, it was proposed in 1999 that helical jump motion plays an important role in crystal deformation. On the other hand, the new structures induced by deformation also influence the molecular motions and resultant properties of deformed polymers. Such processing-structure-property relationship is very important to understand the polymer behaviors as well as to inform the polymer industry. In this dissertation, using the advanced tool of solid-state NMR (ss-NMR), we achieve three goals: Firstly, we investigate the hierarchical crystalline structural changes of isotactic polypropylene (i PP) upon high temperature stretching to understand the deformation process. Secondly, we evaluate the roles of local packing structure and crystal thickness in determining the stem motions and thermal properties of deformed alpha-form iPP. Thirdly, we utilize 13C-labeled isotactic polypropylene (iPP) to trace the change of chain folding number as a function of e to conclude molecular-level deformation mechanism. To realize the first and second goals, the chain packing, crystal thickness, molecular dynamics, and melting temperature (Tm) of a-form iPP drawn uniaxially at high temperatures of 100 - 150 °C were investigated using solid-state (SS) NMR and DSC. Two types of iPP samples with disordered (alpha1) and relatively ordered (alpha2-rich) packing structures were prepared via different thermal treatments and drawn up to an engineering strain ( e) of

  16. Modeling Large-Strain, High-Rate Deformation in Metals

    SciTech Connect

    Lesuer, D R; Kay, G J; LeBlanc, M M

    2001-07-20

    The large strain deformation response of 6061-T6 and Ti-6Al-4V has been evaluated over a range in strain rates from 10{sup -4} s{sup -1} to over 10{sup 4} s{sup -1}. The results have been used to critically evaluate the strength and damage components of the Johnson-Cook (JC) material model. A new model that addresses the shortcomings of the JC model was then developed and evaluated. The model is derived from the rate equations that represent deformation mechanisms active during moderate and high rate loading. Another model that accounts for the influence of void formation on yield and flow behavior of a ductile metal (the Gurson model) was also evaluated. The characteristics and predictive capabilities of these models are reviewed.

  17. Analysis of dense packing of highly deformed grains

    NASA Astrophysics Data System (ADS)

    Vu, Thi Lo; Nezamabadi, Saeid; Barés, Jonathan; Mora, Serge

    2017-06-01

    This paper concerns modeling of soft granular materials in which the grains are highly deformable. In order to simulate these materials, an approach based on an implicit formulation of the Material Point Method in the context of the finite strain theory, allowing for large deformations of grains, coupled with the Contact Dynamics method for the treatment of unilateral frictional contacts between grains, is proposed. In this context, the Mooney-Rivlin constitutive relationship is applied with two different set of elastic parameters. Considering these two material behaviors, a uniaxial compression of 2D soft granular packings is analyzed. The stress-strain relation and the evolution of the packing fraction as well as of the connectivity of the grains are discussed.

  18. Ultrasound Velocity Measurements in High-Chromium Steel Under Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Lunev, Aleksey; Bochkareva, Anna; Barannikova, Svetlana; Zuev, Lev

    2016-04-01

    In the present study, the variation of the propagation velocity of ultrasound in the plastic deformation of corrosion-resistant high-chromium steel 40X13 with ferrite-carbide (delivery status), martensitic (quenched) and sorbitol (after high-temperature tempering) structures have beem studied/ It is found that each state shows its view of the loading curve. In the delivery state diagram loading is substantially parabolic throughout, while in the martensitic state contains only linear strain hardening step and in the sorbitol state the plastic flow curve is three-step. The velocity of ultrasonic surface waves (Rayleigh waves) was measured simultaneously with the registration of the loading curve in the investigated steel in tension. It is shown that the dependence of the velocity of ultrasound in active loading is determined by the law of plastic flow, that is, the staging of the corresponding diagram of loading. Structural state of the investigated steel is not only changing the type of the deformation curve under uniaxial tension, but also changes the nature of ultrasound speed of deformation.

  19. Measurement of high viscosity with laser induced surface deformation technique

    SciTech Connect

    Yoshitake, Y.; Mitani, S.; Sakai, K.; Takagi, K.

    2005-01-15

    A technique for viscosity measurement was developed based on the principle of laser-induced surface deformation. Light incident into liquids increases its momentum due to the difference in refractive index and gives the surface an upward force as a reaction. The plane surface thus swells up and deforms, and the shape is determined so that the force is balanced with the surface tension and the gravity. On sudden laser irradiation, the deformation inevitably accompanies a viscous flow and exhibits a relaxational behavior with a delay time, which gives the viscosity. Theoretical prediction of the step-response function was given that takes surface tension waves excited by the laser into consideration. Nd-yttritium-aluminum-garnet laser with 0.6 W output was focused to {approx}200 {mu}m beam waist and used for the pumping. The deformation process was observed sensitively with another probe laser illuminating the activated area. This system was tested with the standard liquids for viscosity ranging from 1 to 10{sup 6} cSt. The results demonstrated the validity of this technique, though a correction for the inertia effect was needed in the range lower than 10 cSt. Further, effect of the thermal expansion by a slight optical absorption was discussed. This technique is especially useful at high viscosities since the measurement takes only a few seconds even in the specimen with 10{sup 6} cSt. Besides the rapidity, it has a great advantage of a noncontact feature and is appropriate for measuring the liquids that strongly dislike contamination. It has also potential applications in industries, measurement of liquids isolated in a production line, for instance.

  20. High Pressure Experimental Deformation in Talc Assemblies: Cheap, Easy, Wrong

    NASA Astrophysics Data System (ADS)

    Stewart, E. D.; Holyoke, C. W.; Kronenberg, A. K.; Newman, J.

    2011-12-01

    Early methods of applying high pressures in the Griggs piston-cylinder triaxial deformation apparatus employed solid confining media thought to be weak compared with the silicate samples under investigation. Griggs apparatus sample assemblies with talc as the confining medium have been used in large numbers of experimental studies of rock deformation at pressures of 1.0 to 2.0 GPa. Modern methods now use solid and molten salts as confining media, with flow strengths that are low for solid salts (at elevated temperatures) and zero for molten salts; yet, talc continues to be used when deformation microstructures are used to infer differential stress. Recent comparison experiments conducted in the Griggs apparatus and gas apparatus have yielded calibrations that enable accurate stress measurements using solid and molten salt assemblies. These calibrations demonstrate that differential stresses measured at high confining pressures using the Griggs apparatus are systematically high, yet they are correctable. They also indicate that a significant portion of the required stress correction is due to friction in the nested loading column of the apparatus. No other correction is required for molten salt assemblies and the offset in stress measurements using solid salt assemblies, due to the strength of solid salt, is considerably smaller than previously thought. Encouraged by these calibrations for solid and molten salt assemblies, we performed similar comparison experiments in the Griggs apparatus using traditional, easy-to-use talc assemblies with the goal of developing another calibration for high-pressure stress measurements. Following the same procedures as used in our earlier calibrations, we deformed molybdenum and TZM alloy cylinders using a talc assembly at the same temperatures and strain rates (600-1000{circ}C and 1{ast}10^{-4}/s) as used in gas apparatus experiments. The apparent strengths of the samples deformed below the talc dehydration temperature were at

  1. High Shear Deformation to Produce High Strength and Energy Absorption in Mg Alloys

    SciTech Connect

    Joshi, Vineet V.; Jana, Saumyadeep; Li, Dongsheng; Garmestani, Hamid; Nyberg, Eric A.; Lavender, Curt A.

    2014-02-01

    Magnesium alloys have the potential to reduce the mass of transportation systems however to fully realize the benefits it must be usable in more applications including those that require higher strength and ductility. It has been known that fine grain size in Mg alloys leads to high strength and ductility. However, the challenge is how to achieve this optimal microstructure in a cost effective way. This work has shown that by using optimized high shear deformation and second phase particles of Mg2Si and MgxZnZry the energy absorption of the extrusions can exceed that of AA6061. The extrusion process under development described in this presentation appears to be scalable and cost effective. In addition to process development a novel modeling approach to understand the roles of strain and state-of-strain on particle fracture and grain size control has been developed

  2. Characteristics of aluminum alloy microplastic deformation in different structural states

    SciTech Connect

    Seregin, G.V.; Efimenko, L.L.; Leonov, M.V.

    1995-07-01

    The solution to the problem of improving the mechanical properties (including cyclic strength) of structural materials is largely dependent on our knowledge of the laws governing the development of microplastic deformations in them. The effect of heat and mechanical treatment on the elastoplastic properties and fatigue resistance of the commercial aluminum alloys AK4-1 and D16 is analyzed.

  3. 3D High Resolution Mesh Deformation Based on Multi Library Wavelet Neural Network Architecture

    NASA Astrophysics Data System (ADS)

    Dhibi, Naziha; Elkefi, Akram; Bellil, Wajdi; Amar, Chokri Ben

    2016-12-01

    This paper deals with the features of a novel technique for large Laplacian boundary deformations using estimated rotations. The proposed method is based on a Multi Library Wavelet Neural Network structure founded on several mother wavelet families (MLWNN). The objective is to align features of mesh and minimize distortion with a fixed feature that minimizes the sum of the distances between all corresponding vertices. New mesh deformation method worked in the domain of Region of Interest (ROI). Our approach computes deformed ROI, updates and optimizes it to align features of mesh based on MLWNN and spherical parameterization configuration. This structure has the advantage of constructing the network by several mother wavelets to solve high dimensions problem using the best wavelet mother that models the signal better. The simulation test achieved the robustness and speed considerations when developing deformation methodologies. The Mean-Square Error and the ratio of deformation are low compared to other works from the state of the art. Our approach minimizes distortions with fixed features to have a well reconstructed object.

  4. Deformation-induced localized solid-state amorphization in nanocrystalline nickel

    PubMed Central

    Han, Shuang; Zhao, Lei; Jiang, Qing; Lian, Jianshe

    2012-01-01

    Although amorphous structures have been widely obtained in various multi-component metallic alloys, amorphization in pure metals has seldom been observed and remains a long-standing scientific curiosity and technological interest. Here we present experimental evidence of localized solid-state amorphization in bulk nanocrystalline nickel introduced by quasi-static compression at room temperature. High-resolution electron microscope observations illustrate that nano-scale amorphous structures present at the regions where severe deformation occurred, e.g. along crack paths or surrounding nano-voids. These findings have indicated that nanocrystalline structures are highly desirable for promoting solid-state amorphization, which may provide new insights for understanding the nature of the crystalline-to-amorphous transformation and suggested a potential method to produce elemental metallic glasses that have hardly been available hitherto through rapid solidification. PMID:22768383

  5. Phase sensitivity in deformed-state superposition considering nonlinear phase shifts

    NASA Astrophysics Data System (ADS)

    Berrada, K.

    2016-07-01

    We study the problem of the phase estimation for the deformation-state superposition (DSS) under perfect and lossy (due to a dissipative interaction of DSS with their environment) regimes. The study is also devoted to the phase enhancement of the quantum states resulting from a generalized non-linearity of the phase shifts, both without and with losses. We find that such a kind of superposition can give the smallest variance in the phase parameter in comparison with usual Schrödinger cat states in different order of non-linearity even if for a larger average number of photons. Due to the significance of how a system is quantum correlated with its environment in the construction of a scalable quantum computer, the entanglement between the DSS and its environment is investigated during the dissipation. We show that partial entanglement trapping occurs during the dynamics depending on the kind of deformation and mean photon number. These features make the DSS with a larger average number of photons a good candidate for implementation of schemes of quantum optics and information with high precision.

  6. High-strain shear deformation of olivine aggregates with different iron contents

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zimmerman, M. E.; Kohlstedt, D. L.

    2006-12-01

    High-strain deformation experiments were conducted at high temperature and high pressure on olivine aggregates with two different iron contents in order to investigate both the mechanical behavior and the microstructural development. Torsion experiments were conducted in a gas-medium deformation apparatus under anhydrous conditions to shear strains of ~4 at a constant angular velocity, a temperature of 1473K, and a confining pressure of 300MPa. The compositions of the aggregates were Fo50 and Fo70. The applied shear strain rate ranged from 10-4 to 10^{-5} s-1, yielding shear stresses supported by the sample of ~100 MPa. To examine microstructural development, a series of parallel sections were examined. The first section was cut near the outside margin and the last section was cut along the central plane of the cyllindrical sample. Olivine samples deformed in the dislocation creep regime strain weakened before approaching steady state. A strong lattice preferred orientation (LPO) dominated the microstructure along with significant grain flattening, elongation, and dynamic recrystallization. The LPO indicates that slip occurred primarily on the (0kl)[100] slip system. This observation is consistent with the LPO observed by Bystricky et al. (2000) for samples of Fo90 that were also deformed in torsion. Bystricky, M., K. Kunze, L. Burlini, J.-P. Burg, Science, 290:1564-1567 (2000).

  7. Analytical Modeling of the High Strain Rate Deformation of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.; Gilat, Amos

    2003-01-01

    The results presented here are part of an ongoing research program to develop strain rate dependent deformation and failure models for the analysis of polymer matrix composites subject to high strain rate impact loads. State variable constitutive equations originally developed for metals have been modified in order to model the nonlinear, strain rate dependent deformation of polymeric matrix materials. To account for the effects of hydrostatic stresses, which are significant in polymers, the classical 5 plasticity theory definitions of effective stress and effective plastic strain are modified by applying variations of the Drucker-Prager yield criterion. To verify the revised formulation, the shear and tensile deformation of a representative toughened epoxy is analyzed across a wide range of strain rates (from quasi-static to high strain rates) and the results are compared to experimentally obtained values. For the analyzed polymers, both the tensile and shear stress-strain curves computed using the analytical model correlate well with values obtained through experimental tests. The polymer constitutive equations are implemented within a strength of materials based micromechanics method to predict the nonlinear, strain rate dependent deformation of polymer matrix composites. In the micromechanics, the unit cell is divided up into a number of independently analyzed slices, and laminate theory is then applied to obtain the effective deformation of the unit cell. The composite mechanics are verified by analyzing the deformation of a representative polymer matrix composite (composed using the representative polymer analyzed for the correlation of the polymer constitutive equations) for several fiber orientation angles across a variety of strain rates. The computed values compare favorably to experimentally obtained results.

  8. Entanglement generation from deformed spin coherent states using a beam splitter

    NASA Astrophysics Data System (ADS)

    Berrada, K.; El Baz, M.; Saif, F.; Hassouni, Y.; Mnia, S.

    2009-07-01

    Using the linear entropy as a measure of entanglement, we investigate the effect of a beam splitter on the Perelomov coherent states for the q-deformed Uq(su(2)) algebra. We distinguish two cases: in the classical q → 1 limit, we find that the states become Glauber coherent states as the spin tends to infinity; whereas for q ≠ 1, the states, contrary to the earlier case, become entangled as they pass through a beam splitter. The entanglement strongly depends on the q-deformation parameter and the amplitude Z of the state.

  9. Skyrme random-phase-approximation description of lowest Kπ=2γ+ states in axially deformed nuclei

    NASA Astrophysics Data System (ADS)

    Nesterenko, V. O.; Kartavenko, V. G.; Kleinig, W.; Kvasil, J.; Repko, A.; Jolos, R. V.; Reinhard, P.-G.

    2016-03-01

    The lowest quadrupole γ -vibrational Kπ=2+ states in axially deformed rare-earth (Nd, Sm, Gd, Dy, Er, Yb, Hf, W) and actinide (U) nuclei are systematically investigated within the separable random-phase-approximation (SRPA) based on the Skyrme functional. The energies Eγ and reduced transition probabilities B (E 2 ) of 2γ+ states are calculated with the Skyrme forces SV-bas and SkM*. The energies of two-quasiparticle configurations forming the SRPA basis are corrected by using the pairing blocking effect. This results in a systematic downshift of Eγ by 0.3-0.5 MeV and thus in a better agreement with the experiment, especially in Sm, Gd, Dy, Hf, and W regions. For other isotopic chains, a noticeable overestimation of Eγ and too weak collectivity of 2γ+ states still persist. It is shown that domains of nuclei with low and high 2γ+ collectivity are related to the structure of the lowest two-quasiparticle states and conservation of the Nilsson selection rules. The description of 2γ+ states with SV-bas and SkM* is similar in light rare-earth nuclei but deviates in heavier nuclei. However SV-bas much better reproduces the quadrupole deformation and energy of the isoscalar giant quadrupole resonance. The accuracy of SRPA is justified by comparison with exact RPA. The calculations suggest that a further development of the self-consistent calculation schemes is needed for a systematic satisfactory description of the 2γ+ states.

  10. Deformation Experiment on Quartz Aggregates with High Porosity and High Water Contents at High Pressure and Temperature

    NASA Astrophysics Data System (ADS)

    Okazaki, K.; Hirth, G.

    2016-12-01

    Large earthquakes typically nucleate near the depth limit of seismogenic zones. In these areas, high Vp/Vs ratios are commonly observed, indicating the presence of high pore fluid pressures. Thus, it is important to understand how the water content (both water in the crystal and in the pores) and the pore structure affect the rheology of polycrystalline materials. We conducted deformation experiments on quartz aggregates using a Griggs-type deformation apparatus. Samples were hot-pressed from silica gels, which contain 9 wt% water within the amorphous structure and absorbed on the surface. Hydrostatic experiments within the α-quartz stability field at a pressure of 1.5 GPa and 900°C indicate that hot-pressed samples are composed of quartz and no relict of amorphous material is present. The average grain size and porosity of the hot-pressed aggregates is about 4 μm and 23%, respectively. The grain shape is equigranular and no crystallographic preferred orientation (CPO) is observed. Initial results from general shear experiments on the hot-pressed quartz aggregates at the equivalent strain rate of 1.5 x 10-4 1/s, a pressure of 1.5 GPa and 900°C show very low strength (equivalent stress of 140 MPa) and nominally steady state flow at shear strains up to 3.5. The samples show no CPO and evidence for strain localization along R1 riedel shears. In contrast, deformation experiments on cores of quartzite show dislocation creep at this pressure/temperature condition. The measured stress from the new experiments is significantly lower than predicted by the wet quartz flow law (e.g., Hirth et al., 2001). The low flow stress and absence of CPO suggest the operation of grain-size sensitive flow, or perhaps that the effective pressure law is still applicable and the sample deforms by a distributed semi-brittle flow process

  11. The high-speed deformation behavior of TRIP steels

    NASA Astrophysics Data System (ADS)

    Choi, Ildong; Bruce, Denise M.; Matlock, David K.; Speer, John G.

    2008-04-01

    The high-speed deformation behavior of TRIP steel was investigated at strain rates ranging from 10-2 s-1 to 103 s-1. The effects of metallurgical factors, such as the rolling direction, thickness, and gage length, on the tensile properties at various strain rates were evaluated. The ultimate tensile strength, uniform elongation, strain rate sensitivity, absorbed energy, and strain-hardening exponent are reported. In general, the strength increases and the ductility decreases as the strain rate increases. The samples with a high amount of retained austenite had two distinct regions of strain rate sensitivity, showing high strain rate sensitivity over a strain rate of 102 s-1. The tensile properties were not affected by the gage length and thickness of the tensile samples; however, the rolling direction of the tensile samples affected the UTS values slightly. The absorbed energy of the TRIP steel greatly exceeded that of HSLA steel.

  12. Revisiting the deformed high shoreline of Lake Bonneville

    NASA Astrophysics Data System (ADS)

    Chen, Christine Y.; Maloof, Adam C.

    2017-03-01

    Since G. K. Gilbert's foundational work in the eastern Great Basin during the late 1800s, the late Pleistocene Lake Bonneville (30-10 ka) has been recognized as a natural laboratory for various Quaternary studies, including lithospheric deformation due to surface loading and climate-forced water balance changes. Such studies rely on knowledge of the elevations of Lake Bonneville's paleoshoreline features and depositional landforms, which record a complex history of lake level variations induced by deglacial climate change. In this paper, we present (1) a new compilation of 178 elevation measurements of shoreline features marking Lake Bonneville's greatest areal extent measured using high-precision differential GPS (dGPS), and (2) a reconstructed outline of the highest shoreline based on dGPS measurements, submeter-resolution aerial imagery, topographic digital elevation models (DEMs), and field observations. We also (3) devise a simplified classification scheme and method for standardizing shoreline elevation measurement for different shoreline morphologies that includes constraints on the position of the still water level (SWL) relative to each feature type. The deformation pattern described by these shoreline features can help resolve the relative effects of local hydro-isostasy due to the lake load and regional solid earth deflection due to the Laurentide ice sheet, with potential implications for Earth rheology, glacial isostatic adjustment, and eustatic sea level change.

  13. High strain rate deformation of NiAl

    SciTech Connect

    Maloy, S.A.; Gray, G.T. III; Darolia, R.

    1994-07-01

    NiAl is a potential high temperature structural material. Applications for which NiAl is being considered (such as rotating components in jet engines) requires knowledge of mechanical properties over a wide range of strain rates. Single crystal NiAl (stoichiometric and Ni 49.75Al 0.25Fe) has been deformed in compression along [100] at strain rates of 0.001, 0.1/s and 2000/s and temperatures of 76,298 and 773K. <111> slip was observed after 76K testing at a strain rate of 0.001/s and 298K testing at a strain rate of 2000/s. Kinking was observed after deformation at 298K and a strain rate of 0.001/s and sometimes at 298 K and a strain rate of 0.1/s. Strain hardening rates of 8200 and 4000 MPa were observed after 773 and 298K testing respectively, at a strain rate of 2000/s. Results are discussed in reference to resulting dislocation substructure.

  14. Measuring Crustal Deformation in Europe by High Precision Geodetic VLBI

    NASA Astrophysics Data System (ADS)

    Campbell, J.; Nothnagel, A.; Vennebusch, M.

    2002-06-01

    At the western tip of the Eurasian plate, the European continent is besieged by thrusting and receding neighbour plates causing deformations and ruptures of the Earth's crust evidenced by earthquakes and volcanic outbursts. Measuring the extent and progress of crustal deformation has become one of the primary tasks of geodesists and geophysicists. Realizing that Europe enjoys one of the densest networks of radio telescopes especially equipped for high precision, geodetic VLBI has provided the incentive to organise a campaign of regular geodetic VLBI observations in the European network of fixed radio telescopes. The measurements have been carried out since the late eighties at an average rate of six sessions per year. From these data, site coordinates, baseline length changes and station velocity vectors have been derived with steadily increasing accuracy. The overall picture of the observed present-day site motions emulates quite well the pattern of tectonic motions inferred from the geotectonic setting of central Europe and the western Mediterranean. Interesting details are emerging for horizontal motions of the three stations in Italy, which are strongly affected by the complex interactions between the different tectonic regimes in this area. The accuracy of the vertical components is also improving with increasing length of the observational record, allowing to detect significant trends among the relative vertical motions of the sites. The geodetic VLBI network operations have received supportive funding by the European Union under the 2nd and 4th Framework Programmes.

  15. Time-dependent q-deformed bi-coherent states for generalized uncertainty relations

    NASA Astrophysics Data System (ADS)

    Gouba, Laure

    2015-07-01

    We consider the time-dependent bi-coherent states that are essentially the Gazeau-Klauder coherent states for the two dimensional noncommutative harmonic oscillator. Starting from some q-deformations of the oscillator algebra for which the entire deformed Fock space can be constructed explicitly, we define the q-deformed bi-coherent states. We verify the generalized Heisenberg's uncertainty relations projected onto these states. For the initial value in time, the states are shown to satisfy a generalized version of Heisenberg's uncertainty relations. For the initial value in time and for the parameter of noncommutativity θ = 0, the inequalities are saturated for the simultaneous measurement of the position-momentum observables. When the time evolves, the uncertainty products are different from their values at the initial time and do not always respect the generalized uncertainty relations.

  16. Generalized q-deformed Tamm-Dancoff oscillator algebra and associated coherent states

    SciTech Connect

    Chung, Won Sang; Hounkonnou, Mahouton Norbert Arjika, Sama

    2014-08-15

    In this paper, we propose a full characterization of a generalized q-deformed Tamm-Dancoff oscillator algebra and investigate its main mathematical and physical properties. Specifically, we study its various representations and find the condition satisfied by the deformed q-number to define the algebra structure function. Particular Fock spaces involving finite and infinite dimensions are examined. A deformed calculus is performed as well as a coordinate realization for this algebra. A relevant example is exhibited. Associated coherent states are constructed. Finally, some thermodynamics aspects are computed and discussed.

  17. High-temperature deformation behavior in Sr TiO{sub 3} ceramics.

    SciTech Connect

    Singh, D.; Lorenzo-Martin, M.; Chen, G.; Gutierrez-Mora, F.; Routbort, J. L.; Nuclear Engineering Division; Univ. de Sevilla

    2007-01-01

    The high-temperature deformation behavior of a polycrystalline strontium titanate (SrTiO{sub 3}) ceramic (6 {micro}m grain size) was investigated at temperatures of 1200-1345 C in an argon atmosphere. Compressive deformation tests were conducted at strain rates ranging from 5 x 10{sup -6} to 5 x 10{sup -5} s{sup -1}. Steady-state flow stresses were 0.05-30 MPa and increased with increasing strain rates. Stress exponents of {approx}1, at temperatures >1200 C, indicated a viscous diffusion-controlled deformation with an activation energy of {approx}628 {+-} 24 kJ/mol. Comparison of activation energy with literature data suggests diffusion of cations as the rate-controlling mechanism. Absence of cavitation and grain-shape changes were consistent with grain-boundary sliding as the principal deformation mechanism. The electron back-scattered diffraction (EBSD) technique was used to determine the grain orientation as a function of applied strain. The results indicate that some of the grains rotate with cumulative rotation as large as 7 degrees at a strain of 4%.

  18. Charged particle beam scanning using deformed high gradient insulator

    SciTech Connect

    Chen, Yu -Jiuan

    2015-10-06

    Devices and methods are provided to allow rapid deflection of a charged particle beam. The disclosed devices can, for example, be used as part of a hadron therapy system to allow scanning of a target area within a patient's body. The disclosed charged particle beam deflectors include a dielectric wall accelerator (DWA) with a hollow center and a dielectric wall that is substantially parallel to a z-axis that runs through the hollow center. The dielectric wall includes one or more deformed high gradient insulators (HGIs) that are configured to produce an electric field with an component in a direction perpendicular to the z-axis. A control component is also provided to establish the electric field component in the direction perpendicular to the z-axis and to control deflection of a charged particle beam in the direction perpendicular to the z-axis as the charged particle beam travels through the hollow center of the DWA.

  19. Deformation effects of droplet fluctuations on dynamics in an Ising ferromagnetic state

    NASA Technical Reports Server (NTRS)

    Nakanishi, Hiizu

    1990-01-01

    Deformation effects of droplet fluctuations on the dynamics in an Ising ferromagnetic state in two dimensions are studied in the case of an order-parameter-nonconserving system by investigating an equation of motion for a domain boundary. Analytic and numerical studies show that the deformation effects on the survival probability of the droplets simply result in changing the time scale or renormalizing a kinetic coefficient.

  20. Lifetime measurements of high-lying short lived states in {sup 69}As

    SciTech Connect

    Matejska-Minda, M.; Bednarczyk, P.; Fornal, B.; Ciemala, M.; Kmiecik, M.; Krzysiek, M.; Maj, A.; Meczynski, W.; Myalski, S.; Styczen, J.; Zieblinski, M.; Angelis, G. de; Huyuk, T.; Michelagnoli, C.; Sahin, E.; Aydin, S.; Farnea, E.; Menegazzo, R.; Recchia, F.; Ur, C. A.; and others

    2012-10-20

    Lifetimes of high-spin states in {sup 69}As have been measured using Doppler shift attenuation technique with the GASP and RFD setup. The determined transition probabilities indicate large deformation associated with some rotational bands in this nucleus.

  1. Lifetime measurements of high-lying short lived states in 69As

    NASA Astrophysics Data System (ADS)

    Matejska-Minda, M.; Bednarczyk, P.; Fornal, B.; Ciemała, M.; Kmiecik, M.; Krzysiek, M.; Maj, A.; Meczyński, W.; Myalski, S.; Styczén, J.; Ziebliński, M.; de Angelis, G.; Huyuk, T.; Michelagnoli, C.; Sahin, E.; Aydin, S.; Farnea, E.; Menegazzo, R.; Recchia, F.; Ur, C. A.; Brambilla, S.; Leoni, S.; Montanari, D.; Jaworski, G.; Palacz, M.; Wadsworth, R.

    2012-10-01

    Lifetimes of high-spin states in 69As have been measured using Doppler shift attenuation technique with the GASP and RFD setup. The determined transition probabilities indicate large deformation associated with some rotational bands in this nucleus.

  2. Triaxial superdeformed and normal-deformed high-spin band structures in {sup 170}Hf

    SciTech Connect

    Neusser-Neffgen, A.; Huebel, H.; Bringel, P.; Domscheit, J.; Mergel, E.; Nenoff, N.; Singh, A.K.; Hagemann, G.B.; Jensen, D.R.; Bhattacharya, S.; Curien, D.; Dorvaux, O.; Hannachi, F.; Lopez-Martens, A.

    2006-03-15

    The high-spin structure of {sup 170}Hf was investigated using the EUROBALL spectrometer. The previously known level scheme was extended in the low-spin region as well as to higher spins, and several new bands were discovered. In particular, two bands were identified which show the characteristics of triaxial superdeformation. One of these bands is strongly populated, and its excitation energy and spins are established. Configuration assignments are made to the normal-deformed bands based on comparisons of their properties with cranked shell model calculations. The results for the very high spin states provide important input for such calculations.

  3. Variable-intercept panel model for deformation zoning of a super-high arch dam.

    PubMed

    Shi, Zhongwen; Gu, Chongshi; Qin, Dong

    2016-01-01

    This study determines dam deformation similarity indexes based on an analysis of deformation zoning features and panel data clustering theory, with comprehensive consideration to the actual deformation law of super-high arch dams and the spatial-temporal features of dam deformation. Measurement methods of these indexes are studied. Based on the established deformation similarity criteria, the principle used to determine the number of dam deformation zones is constructed through entropy weight method. This study proposes the deformation zoning method for super-high arch dams and the implementation steps, analyzes the effect of special influencing factors of different dam zones on the deformation, introduces dummy variables that represent the special effect of dam deformation, and establishes a variable-intercept panel model for deformation zoning of super-high arch dams. Based on different patterns of the special effect in the variable-intercept panel model, two panel analysis models were established to monitor fixed and random effects of dam deformation. Hausman test method of model selection and model effectiveness assessment method are discussed. Finally, the effectiveness of established models is verified through a case study.

  4. Analysis of deformation bands in the Aztec Sandstone, Valley of Fire State Park, Nevada

    SciTech Connect

    Hill, R.E. )

    1993-04-01

    This research concerns two types of deformation structures, deformation bands and low-angle slip surfaces, that occur in the Aztec Sandstone in the Valley of Fire State Park, Nevada. Deformation bands were analyzed by mapping and describing over 500 of the structures on a bedding surface of about 560 square meters. Deformation bands are narrow zones of reduced porosity which form resistant ribs in the sandstone. Three sets of deformation bands are present at the study site (type 1,2, and 3). Type 1 and 2 bands are interpreted as coeval and form a conjugate set with a dihedral angle of 90 degrees. These sets are usually composed of multiple bands. A third set is interpreted to be subsidiary to the older set, and intersections angles with the earlier formed sets are approximately 45 degrees. In contrast with the older sets, the third set is nearly always a single band which is sinuous or jagged along its length. All three sets of deformation bands are crosscut and sometimes offset by low-angle slip surfaces. These faults have reverse dip slip displacement and locally have mullions developed. Displacements indicate eastward movement of the hanging wall which is consistent with the inferred movements of major Mesozoic thrust faults in the vicinity. The change of deformation style from deformation bands to low-angle slip surfaces may document a change in the stress regime. Paleostress interpretation of the deformation band geometry indicates the intermediate stress axis is vertical. The low-angle slip surfaces indicate the least compressive stress axis is vertical. This possible change in stress axes may be the result of increasing pore pressure associated with tectonic loading from emplacement of the Muddy Mountain thrust.

  5. High-temperature deformation and recrystallization: A variational analysis and its application to olivine aggregates

    NASA Astrophysics Data System (ADS)

    Hackl, Klaus; Renner, JöRg

    2013-03-01

    We develop a framework for a variational analysis of microstructural evolution during inelastic high-temperature deformation accommodated by dislocation mechanisms and diffusive mass transport. A polycrystalline aggregate is represented by a distribution function characterizing the state of individual grains by three variables, dislocation density, grain size, and elastic strain. The aggregate's free energy comprises elastic energy and energies of lattice distortions due to dislocations and grain boundaries. The work performed by the external loading is consumed by changes in the number of defects and their migration leading to inelastic deformation. The variational approach minimizes the rate of change of free energy with the evolution of the state variables under constraints on the aggregate volume, on a relation between changes in plastic strain and dislocation density, and on the form of the dissipation functionals for defect processes. The constrained minimization results in four basic evolution equations, one each for the evolution in grain size and dislocation density and flow laws for dislocation and diffusion creep. Analytical steady state scaling relations between stress and dislocation density and grain size (piezometers) are derived for quasi-homogeneous materials characterized by a unique relation between grain size and dislocation density. Our model matches all currently available experimental observations regarding high-temperature deformation of olivine aggregates with plausible values for the involved micromechanical model parameters. The relation between strain rate and stress for olivine aggregates maintaining a steady state microstructure is distinctly nonlinear in stark contrast to the majority of geodynamical modeling relying on linear relations, i.e., Newtonian behavior.

  6. High-pressure deformation of serpentine + olivine aggregates

    NASA Astrophysics Data System (ADS)

    Hilairet, N.; Ferrand, T. P.; Raterron, P.; Merkel, S.; Guignard, J.; Langrand, C.; Schubnel, A.

    2015-12-01

    Serpentinization is expected to occur when fluids are released from the dehydrating subducting slabs and migrate into shear zones and the mantle wedge peridotites. At shallow depths (15-30km) a few percent volume serpentine can lower the viscosity of peridotites by almost an order of magnitude [1]. However, the deformation mechanisms are not easily extrapolable to deeper contexts. The rheology of a rock with two phases of contrasted mechanical properties is highly non-linear with composition and cannot be modelled from its end-members. Here we investigate the rheology of serpentine + olivine « synthetic » peridotites with varying serpentine content (5 to 50%) at high pressure (2- 3 GPa, ca. 60-90 km depth), using the D-DIA large volume press and synchrotron powder X-ray diffraction and imaging. The results will provide insights on the conditions under which serpentinized peridotites evolve in a regime dominated by the rheology of the strongest phase (olivine) or the weakest phase (antigorite). [1] Escartin et al, Journal of Geophysical Research, 1997

  7. Study of natural rubber crosslinked in the state of uniaxial deformation

    NASA Astrophysics Data System (ADS)

    Dubrović, I.; Klepac, D.; Valić, S.; Žauhar, G.

    2008-06-01

    A natural rubber (NR) film with the thickness of about 1 mm was prepared by removing the liquid phase from NR latex. Two types of NR films crosslinked by γ-irradiation were investigated: (i) samples irradiated in the relaxed state and (ii) samples irradiated in the state of uniaxial deformation. The total irradiation dose varied from 0 kGy (for nonirradiated NR) to 400 kGy and the degree of deformation, defined as λ=l/ l0 ( l0 and l being the lengths of relaxed and uniaxially deformed sample, respectively), was chosen to be λ=1.0 (relaxed state), λ=1.5 and λ=2.0. The amount of sol and gel phase of NR was determined by extracting the sol component in toluene. A significant decrease in the amount of the sol component (from 14.2% to 33.5%, depending on irradiation dose) was observed by increasing the irradiation dose. It has been shown that the application of deformation during the crosslinking leads to the lower crosslink density. Such an effect can be attributed to the loss of the gel component induced mechanically. The electron spin resonance (ESR) spectra of spin probe diffusing in the NR matrix crosslinked under deformation are influenced by both, the local dynamics of the chain segments and their spacious orientation.

  8. From microjoules to megajoules and kilobars to gigabars: Probing matter at extreme states of deformation

    SciTech Connect

    Remington, Bruce A.; Rudd, Robert E.; Wark, Justin S.

    2015-09-15

    Over the past 3 decades, there has been an exponential increase in work done in the newly emerging field of matter at extreme states of deformation and compression. This accelerating progress is due to the confluence of new experimental facilities, experimental techniques, theory, and simulations. Regimes of science hitherto thought out of reach in terrestrial settings are now being accessed routinely. High-pressure macroscopic states of matter are being experimentally studied on high-power lasers and pulsed power facilities, and next-generation light sources are probing the quantum response of matter at the atomic level. Combined, this gives experimental access to the properties and dynamics of matter from femtoseconds to microseconds in time scale and from kilobars to gigabars in pressure. There are a multitude of new regimes of science that are now accessible in laboratory settings. Examples include planetary formation dynamics, asteroid and meteor impact dynamics, space hardware response to hypervelocity dust and debris impacts, nuclear reactor component response to prolonged exposure to radiation damage, advanced research into light weight armor, capsule dynamics in inertial confinement fusion research, and the basic high energy density properties of matter. We review highlights and advances in this rapidly developing area of science and research.

  9. From microjoules to megajoules and kilobars to gigabars: Probing matter at extreme states of deformation

    NASA Astrophysics Data System (ADS)

    Remington, Bruce A.; Rudd, Robert E.; Wark, Justin S.

    2015-09-01

    Over the past 3 decades, there has been an exponential increase in work done in the newly emerging field of matter at extreme states of deformation and compression. This accelerating progress is due to the confluence of new experimental facilities, experimental techniques, theory, and simulations. Regimes of science hitherto thought out of reach in terrestrial settings are now being accessed routinely. High-pressure macroscopic states of matter are being experimentally studied on high-power lasers and pulsed power facilities, and next-generation light sources are probing the quantum response of matter at the atomic level. Combined, this gives experimental access to the properties and dynamics of matter from femtoseconds to microseconds in time scale and from kilobars to gigabars in pressure. There are a multitude of new regimes of science that are now accessible in laboratory settings. Examples include planetary formation dynamics, asteroid and meteor impact dynamics, space hardware response to hypervelocity dust and debris impacts, nuclear reactor component response to prolonged exposure to radiation damage, advanced research into light weight armor, capsule dynamics in inertial confinement fusion research, and the basic high energy density properties of matter. We review highlights and advances in this rapidly developing area of science and research.

  10. Effects of pairwise versus many-body forces on high-stress plastic deformation

    NASA Astrophysics Data System (ADS)

    Holian, B. L.; Voter, A. F.; Wagner, N. J.; Ravelo, R. J.; Chen, S. P.; Hoover, W. G.; Hoover, C. G.; Hammerberg, J. E.; Dontje, T. D.

    1991-03-01

    We propose a model embedded-atom (many-body) potential and test it against an effective, density-independent, pairwise-additive potential in a variety of nonequilibrium molecular-dynamics simulations of plastic deformation under high stress. Even though both kinds of interactions have nearly the same equilibrium equation of state, the defect energies (i.e., vacancy formation and surface energies) are quite different. As a result, we observe significant qualitative differences in flow behavior between systems characterized by purely pairwise interactions versus higher-order many-body forces.

  11. An Approach for Measuring and Modeling of Plastic Deformation of Metallic Plates during High Velocity Impacts

    SciTech Connect

    O'Toole, Brendan J.; Trabia, Mohamed B.; Roy, Shawoon K.; Somasundarum, Deepak; Jennings, Richard; Matthes, Melissa; Hixson, Robert S.; Becker, Steven; Daykin, Edward P.; Pena, Michael T.; Machorro, Eric A.

    2014-05-29

    During high velocity impact experiments, projectile impact creates extreme pressure waves that results in a significant localized deformation within a short period of time. Experiments under these conditions require sophisticated data acquisition technique to better understand the materials deformation mechanisms. Since these experiments are expensive, it is also beneficial to develop accurate computational models that can predict this kind of deformation in high velocity impact events.

  12. Rock Deformation at High Confining Pressure and Temperature.

    DTIC Science & Technology

    debugged, delivered and installed to the contracting agency. Clay specimens of illite, kaolinite and montmorillonite were deformed in tri-axial compression...at 25 and 3000C at a constant confining pressure of 2 kb and a constant strain rate of .0001 sec. The illite and kaolinite are stronger under these...conditions than montmorillonite . Cores from dolomite single crystals were deformed at a confining pressure of 7 kb and temperatures of 300 and 500C

  13. Microscopic description of collective states near the yrast line of nuclei with stable octupole deformation

    NASA Astrophysics Data System (ADS)

    Kvasil, J.; Nazmitdinov, R. G.

    1985-06-01

    Collective states near the yrast line in nuclei with stable octupole deformation are discussed in the framework of the random phase approximation (RPA) based on the cranking model. These vibrational states are characterized by the quantum number of generalized signature (eigenvalue of the operator Sx = PRx-1( π)). In the zero-octupole deformation limit the RPA equations of motion are reduced to the well-known ones characterized by both values of parity and signature, respectively. The connection of the translational and rotational symmetry of the model hamiltonian with the spurious solutions of the RPA equation of motion is discussed. Expressions for the reduced probabilities B(E1), B(E2) and B(E3) are obtained. These expressions confirm the conclusions of phenomenological models for the strong E1 and E3 intraband transitions in nuclei with stable octupole deformation.

  14. Investigating the confining compressibility of STF at high deformation rate

    NASA Astrophysics Data System (ADS)

    Jiang, Weifeng; Gong, Xinglong; Xu, Yulei; Xuan, Shouhu; Jiang, Wanquan; Zhu, Wei; Li, Xiaofeng; Qin, Lijun

    2012-12-01

    The split Hopkinson pressure bar (SHPB) was used to study the compressibility of shear thickening fluid (STF) at high deformation rate. In this study, a steel bulk was introduced into the SHPB system to confine and load the STF. A series of STFs with different particle types (SiO2 and PSt-EA) and volume fractions (63 vol.% and 65 vol.%) were tested and the results were compared. The reliability of the results was proved by repeating the tests and the force balance in suspension. The bulk modulus was used to evaluate the compressibility of STF, which indicated that the SiO2-based STF exhibited a larger compressibility than the PSt-EA-based STF. It was found that the bulk modulus increases with increasing of the strain rate and the volume fraction shows little effect on the bulk modulus. The structure-dependent mechanical property was analyzed and the loading effect of bulk modulus was considered to be originated from the interparticle clustering.

  15. High-load, high-temperature deformation apparatus for synthetic and natural silicate melts

    NASA Astrophysics Data System (ADS)

    Hess, K.-U.; Cordonnier, B.; Lavallée, Y.; Dingwell, D. B.

    2007-07-01

    A unique high-load, high-temperature uniaxial press was developed to measure the rheology of silicate melts and magmatic suspensions at temperature up to 1050°C. This new apparatus is designed to operate at constant stresses (up to 300kN) or constant strain rates (˜10-7 to 100s-1) and further allows us to carry on experiments on samples with high viscosities (˜108 to 1012Pas). The rheological instrument represents an advance in that it accommodates homogeneously heated samples (±2°C) of voluminous sizes (up to 790cm3) which permit the insertion of thermocouples to monitor temperature distribution evolutions during measurements. At last this setup allows for accurate measurements of viscosity of natural multiphase materials at strain rates and temperatures common to natural systems. The apparatus aspires to precisely (1) describe the onset of non-Newtonian behavior and its evolution with increasing strain rate until the point of rupture in the brittle regime, (2) constrain the effect of crystals and bubbles on the viscosity, and (3) record heating dissipated through viscous deformation. Here, we present a series of measurements on NIST standard material SRM 717a to calibrate the instrument. We couple the viscosity determined via Gent's equation with certified viscosity data of the standard material to calibrate this state-of-the-art apparatus. This work shows that we can resolve the viscosity of voluminous melt sample within 0.06 logarithmic unit and furthermore present the detection of minor viscous dissipation for a high-temperature, high strain rate experiment.

  16. Adiabatically deformed ensemble: Engineering nonthermal states of matter

    NASA Astrophysics Data System (ADS)

    Kennes, D. M.

    2017-07-01

    We propose a route towards engineering nonthermal states of matter, which show largely unexplored physics. The main idea relies on the adiabatic passage of a thermal ensemble under slow variations of the system Hamiltonian. If the temperature of the initial thermal ensemble is either zero or infinite, the ensemble after the passage is a simple thermal one with the same vanishing or infinite temperature. However, for any finite nonzero temperature, intriguing nonthermal ensembles can be achieved. We exemplify this in (a) a single oscillator, (b) a dimerized interacting one-dimensional chain of spinless fermions, (c) a BCS-type superconductor, and (d) the topological Kitaev chain. We solve these models with a combination of methods: either exactly, numerically using the density matrix renormalization group, or within an approximate functional renormalization group scheme. The designed states show strongly nonthermal behavior in each of the considered models. For example, for the chain of spinless fermions we exemplify how long-ranged nonthermal power-law correlations can be stabilized, and for the Kitaev chain we elucidate how the nonthermal ensemble can largely alter the transition temperature separating topological and trivial phases.

  17. Application of distal metaphyseal osteotomy for treatment of high intermetatarsal angle bunion deformities.

    PubMed

    Oloff, L M; Bocko, A P

    1998-01-01

    This is a retrospective study of 10 patients (13 feet) with moderate to severe hallux valgus who underwent a chevron or modified chevron osteotomy with multiple adjunctive soft-tissue releases for surgical treatment. Radiographic and subjective results were evaluated with an average follow-up of 24 months (range, 10-41). Preoperative criteria included an intermetatarsal (IM) angle of greater than 16 degrees (average of 18.4 degrees) and painful hallux valgus deformity. Average preop hallux abductus was 35.4 degrees (range, 25 degrees-48 degrees). The average reduction in the actual IM angle was (-) 5.2 degrees with a relative IM correction of (-) 11.6 degrees. Average postoperative hallux abductus angle was 7.0 degrees (range, 0 degree-22 degrees). Subjectively, all patients were satisfied with their results and stated they would have the procedure again. No complications were noted in this patient population, including, infection, avascular necrosis, hallux varus, and recurrence of deformity. The chevron osteotomy was found to be successful in this population with high intermetatarsal angles when appropriate consideration was given to correction of soft-tissue-deforming forces and contractures.

  18. Active zone impact on deformation state of non-rigid pavement

    NASA Astrophysics Data System (ADS)

    Mandula, Ján

    2014-06-01

    The paper deals with the design of non-rigid pavement, with emphasis on the effect of active zone on its deformation state. The concepts of determination of active zone are described. The results of numerical modelling of pavement laying on elastic subgrade are presented in the paper

  19. Deformation processes in orogenic wedges: New methods and application to Northwestern Washington State

    NASA Astrophysics Data System (ADS)

    Thissen, Christopher J.

    Permanent deformation records aspects of how material moves through a tectonic environment. The methods required to measure deformation vary based on rock type, deformation process, and the geological question of interest. In this thesis we develop two new methods for measuring permanent deformation in rocks. The first method uses the autocorrelation function to measure the anisotropy present in two-dimensional photomicrographs and three-dimensional X-ray tomograms of rocks. The method returns very precise estimates for the deformation parameters and works best for materials where the deformation is recorded as a shape change of distinct fabric elements, such as grains. Our method also includes error estimates. Image analysis techniques can focus the method on specific fabric elements, such as quartz grains. The second method develops a statistical technique for measuring the symmetry in a distribution of crystal orientations, called a lattice-preferred orientation (LPO). We show that in many cases the symmetry of the LPO directly constrains the symmetry of the deformation, such axial flattening vs. pure shear vs. simple shear. In addition to quantifying the symmetry, the method uses the full crystal orientation to estimate symmetry rather than pole figures. Pole figure symmetry can often be misleading. This method works best for crystal orientations measured in samples deformed by dislocation creep, but otherwise can be used on any mineral without requiring information about slip systems. In Chapter 4 we show how deformation measurements can be used to inform regional tectonic and orogenic models in the Pacific Northwestern United States. A suite of measurements from the Olympic Mountains shows that uplift and deformation of the range is consistent with an orogenic wedge model driven by subduction of the Juan de Fuca plate, and not northward forearc migration of the Oregon block. The deformation measurements also show that deformation within the Olympic Mountains

  20. The Health Impact of Symptomatic Adult Spinal Deformity: Comparison of Deformity Types to United States Population Norms and Chronic Diseases

    PubMed Central

    Bess, Shay; Line, Breton; Fu, Kai-Ming; McCarthy, Ian; Lafage, Virgine; Schwab, Frank; Shaffrey, Christopher; Ames, Christopher; Akbarnia, Behrooz; Jo, Han; Kelly, Michael; Burton, Douglas; Hart, Robert; Klineberg, Eric; Kebaish, Khaled; Hostin, Richard; Mundis, Gregory; Mummaneni, Praveen; Smith, Justin S.

    2016-01-01

    Study Design. A retrospective analysis of a prospective, multicenter database. Objective. The aim of this study was to evaluate the health impact of symptomatic adult spinal deformity (SASD) by comparing Standard Form Version 2 (SF-36) scores for SASD with United States normative and chronic disease values. Summary of Background Data. Recent data have identified radiographic parameters correlating with poor health-related quality of life for SASD. Disability comparisons between SASD patients and patients with chronic diseases may provide further insight to the disease burden caused by SASD. Methods. Consecutive SASD patients, with no history of spine surgery, were enrolled into a multicenter database and evaluated for type and severity of spinal deformity. Baseline SF-36 physical component summary (PCS) and mental component summary (MCS) values for SASD patients were compared with reported U.S. normative and chronic disease SF-36 scores. SF-36 scores were reported as normative-based scores (NBS) and evaluated for minimally clinical important difference (MCID). Results. Between 2008 and 2011, 497 SASD patients were prospectively enrolled and evaluated. Mean PCS for all SASD was lower than U.S. total population (ASD = 40.9; US = 50; P < 0.05). Generational decline in PCS for SASD patients with no other reported comorbidities was more rapid than U.S. norms (P < 0.05). PCS worsened with lumbar scoliosis and increasing sagittal vertical axis (SVA). PCS scores for patients with isolated thoracic scoliosis were similar to values reported by individuals with chronic back pain (45.5 vs 45.7, respectively; P > 0.05), whereas patients with lumbar scoliosis combined with severe sagittal malalignment (SVA >10 cm) demonstrated worse PCS scores than values reported by patients with limited use of arms and legs (24.7 vs 29.1, respectively; P < 0.05). Conclusions. SASD is a heterogeneous condition that, depending upon the type and severity of the deformity

  1. Deformation and Shear Band Development in an Ultrahigh Carbon Steel During High Strain Rate Deformation

    SciTech Connect

    Lesuer, D R; Syn, C K; Sherby, O D

    2004-07-06

    The mechanical response of a pearlitic UHCS-1.3C steel deformed at approximately 4000 s{sup -1} to large strains ({var_epsilon} = -0.9) has been studied. Failure, at both the macroscopic and the microscopic levels has been evaluated, and the ability of the material to absorb energy in compression has been examined. Failure occurred by the development of a shear band. However before failure, extensive buckling of the carbide plates was observed and the UHCS-1.3C material exhibited significant potential for compressive ductility and energy absorption due to the distributed buckling of these plates. Strain localization during adiabatic shear band development resulted in the formation of austenite. Subsequent cooling produced a divorced-eutectoid transformation with associated deformation, which resulted in a microstructure consisting of 50 to 100 nm sized grains. The stress-strain behavior within the shear band has also been determined. The results are used to critically evaluate the maximum shear stress criterion of shear band development. New criteria for the development of shear bands are developed based on a strain energy concept.

  2. Steady-state deformation of some lithium ceramics

    SciTech Connect

    Poeppel, R.B.; Routbort, J.L.; Billone, M.C.; Applegate, D.S.; Buchmann, E.; Londschien, B.

    1987-05-01

    The stress-strain behavior of Li/sub 2/O, LiAlO/sub 2/ and Li/sub 2/ZrO/sub 3/ polycrystals, with densities varying from 0.70 to 0.95 of the theoretical, has been measured in constant-crosshead-speed compression tests at temperatures of 700 to 1000/sup 0/C with strain rates ranging from about 10/sup -6/ to 10/sup -4/ s/sup -1/. A steady-state stress, sigma/sub s/, for which the work-hardening rate becomes zero, was achieved. These results, therefore, yield information equivalent to that obtained from creep experiments. Limited data on LiAlO/sub 2/ and Li/sub 2/ZrO/sub 3/ were obtained. Nevertheless, under comparable conditions the lithium aluminate and zirconate were considerably stronger than the Li/sub 2/O. This finding may be related to differences in crystal structure. It is, however, likely that in operation as a function breeder blanket material, the oxide will swell whereas the aluminate and the zirconate will crack. 5 refs., 6 figs., 1 tab.

  3. Dynamic Impact Deformation Analysis Using High-speed Cameras and ARAMIS Photogrammetry Software

    DTIC Science & Technology

    2010-06-01

    photogrammetry for high-speed impact deformation. ARAMIS is a non-contact measurement system that calculates the strain history of a deformation event...stereo photography and photogrammetry, one can obtain a detail history of a target that undergoes fast rate of deformation. This report is a...desired (highlighted) panel, and then selecting the Edit option. The values in the “Name,” “Calibration scale,” “Cert. Temp.,” and “Exp. Coff

  4. Transition in the deformation mode of nanocrystalline tantalum processed by high-pressure torsion

    SciTech Connect

    Ligda, J.P.; Schuster, B.E.; Wei, Q.

    2012-10-11

    We present quasi-static room temperature compression and nanoindentation data for nanocrystalline and ultrafine grained tantalum processed by high-pressure torsion. Because bulk samples possess an inherent gradient in properties, microstructures were characterized using site-specific transmission electron microscopy and synchrotron X-ray diffraction. Nanocrystalline Ta shows appreciable homogeneous plastic deformation in compression; however, specimens with the smallest grain sizes exhibit localized plastic deformation via shear bands. Microstructural changes associated with this transition in deformation mode are discussed.

  5. New Developments in Deformation Experiments at High Pressure

    SciTech Connect

    Durham, W B; Weidner, D J; Karato, S; Wang, Y

    2004-01-09

    Although the importance of rheological properties in controlling the dynamics and evolution of the whole mantle of Earth is well-recognized, experimental studies of rheological properties and deformation-induced microstructures have mostly been limited to low-pressure conditions. This is mainly a result of technical limitations in conducting quantitative rheological experiments under high-pressure conditions. A combination of factors is changing this situation. Increased resolution of composition and configuration of Earth's interior has created a greater demand for well-resolved laboratory measurement of the effects of pressure on the behavior of materials. Higher-strength materials have become readily available for containing high-pressure research devices, and new analytical capabilities--in particular very bright synchrotron X-ray sources--are now readily available to high-pressure researchers. One of the biggest issues in global geodynamics is the style of mantle convection and the nature of chemical differentiation associated with convectional mass transport. Although evidence for deep mantle circulation has recently been found through seismic tomography (e.g., van der Hilst et al. (1997)), complications in convection style have also been noted. They include (1) significant modifications of flow geometry across the mantle transition zone as seen from high resolution tomographic studies (Fukao et al. 1992; Masters et al. 2000; van der Hilst et al. 1991) and (2) complicated patterns of flow in the deep lower mantle ({approx}1500-2500 km), perhaps caused by chemical heterogeneity (Kellogg et al. 1999; van der Hilst and Karason 1999). These studies indicate that while large-scale circulation involving the whole mantle no doubt occurs, significant deviations from simple flow geometry are also present. Two mineral properties have strong influence on convection: (1) density and (2) viscosity (rheology) contrasts. In the past, the effects of density contrast have

  6. Tidal deformability of neutron and hyperon stars within relativistic mean field equations of state

    NASA Astrophysics Data System (ADS)

    Kumar, Bharat; Biswal, S. K.; Patra, S. K.

    2017-01-01

    We systematically study the tidal deformability for neutron and hyperon stars using relativistic mean field equations of state (EOSs). The tidal effect plays an important role during the early part of the evolution of compact binaries. Although, the deformability associated with the EOSs has a small correction, it gives a clean gravitational wave signature in binary inspiral. These are characterized by various Love numbers kl(l =2 ,3 ,4 ), that depend on the EOS of a star for a given mass and radius. The tidal effect of star could be efficiently measured through an advanced LIGO detector from the final stages of an inspiraling binary neutron star merger.

  7. Equation of state for charge-doping-induced deformation and hardening in cubic crystals

    NASA Astrophysics Data System (ADS)

    Li, Yao; Liu, Xiaofei; Guo, Wanlin

    2017-08-01

    Charge doping would inevitably induce strain, which can significantly influence device performance but cannot be directly predicted by classical mechanical laws. Here we present a set of equations of states for deformable cubic crystals subjected to charge doping by introducing the quantum electronic stress at fixed lattice as equivalent mechanical pressure into the classical hydrostatic pressure-vs-deformation equations. The equations are proved to be efficient for all the cubic crystals considered in this work (diamond, Si, Ge, GaAs, Al, and ZrO2) by first-principles calculations. The proposed method and presented equations should pave a convenient way to predict doping effects on device performance.

  8. Deformation and fracture of low alloy steels at high temperature

    SciTech Connect

    Marriott, D.L.; Stubbins, J.F.; Leckie, F.A.; Muddle, B.

    1988-12-01

    This project formed part of the initiative in the AR TD program to characterize high temperature, time-dependent damage processes in low alloy steels, for use in the construction of coal-gasification plant. This project was broadly aimed at adding to the knowledge base for this bainitic form of 2.25Cr 1Mo steel, as it related to time-dependent performance at elevated temperature. Its original intention was to obtain information in specific grades of 2.25Cr 1Mo steel, in particular those containing reduced residual elements and microalloyed modifications, which were being considered as candidate materials at the time. This objective was subsequently modified, in the course of the contract period, to a more generic study of bainitic steel, using the 2.25Cr 1Mo material as a representative of the class. The main thrust of the project was directed initially at the detrimental effect of cyclic loading on creep resistance and manifesting itself in an apparently severe creep-fatigue interaction. Three subtasks were eventually identified. These are: a study of the evolution of microstructural changes in bainitic materials during steady load creep and under constant amplitude cyclic deformation, investigation of the effect of cyclic softening on the fatigue and creep strength of complex geometries, focusing on circumferentially notched bars, and investigation of the influence of environment as a possible cause of observed fatigue/elevated temperature interaction through its effects on crack initiation and propagation, using EDM notched specimens tested in air and vacuum. Results are discussed. 24 refs., 40 figs., 5 tabs.

  9. Deformation and Phase Transformation Processes in Polycrystalline NiTi and NiTiHf High Temperature Shape Memory Alloys

    NASA Technical Reports Server (NTRS)

    Benafan, Othmane

    2012-01-01

    The deformation and transformation mechanisms of polycrystalline Ni49.9Ti50.1 and Ni50.3Ti29.7Hf20 (in at.%) shape memory alloys were investigated by combined experimental and modeling efforts aided by an in situ neutron diffraction technique at stress and temperature. The thermomechanical response of the low temperature martensite, the high temperature austenite phases, and changes between these two states during thermomechanical cycling were probed and reported. In the cubic austenite phase, stress-induced martensite, deformation twinning and slip processes were observed which helped in constructing a deformation map that contained the limits over which each of the identified mechanisms was dominant. Deformation of the monoclinic martensitic phase was also investigated where the microstructural changes (texture, lattice strains, and phase fractions) during room-temperature deformation and subsequent thermal cycling were compared to the bulk macroscopic response. When cycling between these two phases, the evolution of inelastic strains, along with the shape setting procedures were examined and used for the optimization of the transformation properties as a function of deformation levels and temperatures. Finally, this work was extended to the development of multiaxial capabilities at elevated temperatures for the in situ neutron diffraction measurements of shape memory alloys on the VULCAN Diffractometer at Oak Ridge National Laboratory.

  10. Theory of aging, rejuvenation, and the nonequilibrium steady state in deformed polymer glasses.

    PubMed

    Chen, Kang; Schweizer, Kenneth S

    2010-10-01

    The nonlinear Langevin equation theory of segmental relaxation, elasticity, and mechanical response of polymer glasses is extended to describe the coupled effects of physical aging, mechanical rejuvenation, and thermal history. The key structural variable is the amplitude of density fluctuations, and segmental dynamics proceeds via stress-modified activated barrier hopping on a dynamic free-energy profile. Mechanically generated disorder (rejuvenation) is quantified by a dissipative work argument and increases the amplitude of density fluctuations, thereby speeding up relaxation beyond that induced by the landscape tilting mechanism. The theory makes testable predictions for the time evolution and nonequilibrium steady state of the alpha relaxation time, density fluctuation amplitude, elastic modulus, and other properties. Model calculations reveal a rich dependence of these quantities on preaging time, applied stress, and temperature that reflects the highly nonlinear competition between physical aging and mechanical disordering. Thermal history is "erased" in the long-time limit, although the nonequilibrium steady state is not the literal "fully rejuvenated" freshly quenched glass. The present work provides the conceptual foundation for a quantitative treatment of the nonlinear mechanical response of polymer glasses under a variety of deformation protocols.

  11. Viscoelastic-cycle model of interseismic deformation in the northwestern United States

    USGS Publications Warehouse

    Pollitz, F.F.; McCrory, Patricia; Wilson, Doug; Svarc, Jerry; Puskas, Christine; Smith, Robert B.

    2010-01-01

    We apply a viscoelastic cycle model to a compilation of GPS velocity fields in order to address the kinematics of deformation in the northwestern United States. A viscoelastic cycle model accounts for time-dependent deformation following large crustal earthquakes and is an alternative to block models for explaining the interseismic crustal velocity field. Building on the approach taken in Pollitz et al., we construct a deformation model for the entire western United States-based on combined fault slip and distributed deformation-and focus on the implications for the Mendocino triple junction (MTJ), Cascadia megathrust, and western Washington. We find significant partitioning between strike-slip and dip-slip motion near the MTJ as the tectonic environment shifts from northwest-directed shear along the San Andreas fault system to east-west convergence along the Juan de Fuca Plate. By better accounting for the budget of aseismic and seismic slip along the Cascadia subduction interface in conjunction with an assumed rheology, we revise a previous model of slip for the M~ 9 1700 Cascadia earthquake. In western Washington, we infer slip rates on a number of strike-slip and dip-slip faults that accommodate northward convergence of the Oregon Coast block and northwestward convergence of the Juan de Fuca Plate. Lateral variations in first order mechanical properties (e.g. mantle viscosity, vertically averaged rigidity) explain, to a large extent, crustal strain that cannot be rationalized with cyclic deformation on a laterally homogeneous viscoelastic structure. Our analysis also shows that present crustal deformation measurements, particularly with the addition of the Plate Boundary Observatory, can constrain such lateral variations.

  12. Modeling of high homologous temperature deformation behavior for stress and life-time analyses

    SciTech Connect

    Krempl, E.

    1997-12-31

    Stress and lifetime analyses need realistic and accurate constitutive models for the inelastic deformation behavior of engineering alloys at low and high temperatures. Conventional creep and plasticity models have fundamental difficulties in reproducing high homologous temperature behavior. To improve the modeling capabilities {open_quotes}unified{close_quotes} state variable theories were conceived. They consider all inelastic deformation rate-dependent and do not have separate repositories for creep and plasticity. The viscoplasticity theory based on overstress (VBO), one of the unified theories, is introduced and its properties are delineated. At high homologous temperature where secondary and tertiary creep are observed modeling is primarily accomplished by a static recovery term and a softening isotropic stress. At low temperatures creep is merely a manifestation of rate dependence. The primary creep modeled at low homologous temperature is due to the rate dependence of the flow law. The model is unaltered in the transition from low to high temperature except that the softening of the isotropic stress and the influence of the static recovery term increase with an increase of the temperature.

  13. Stent deformation at the edge of a high pressure balloon.

    PubMed

    Kilic, Ismail Dogu; Foin, Nicolas; Konstantinidis, Nikolaos; Serdoz, Roberta; Caiazzo, Gianluca; Di Mario, Carlo

    2015-12-01

    Focal ultrashort balloons are essential tools for lesion preparation and final stent expansion. However, they may cause a major distortion of the adjacent segments. Here we report a case with a stent deformation emphasizing the importance of utilizing intravascular imaging techniques for optimal interventions.

  14. Structural Deformation of Sm@C88 under High Pressure.

    PubMed

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Ma, Fengxian; Li, Quanjun; Liu, Ran; Zou, Bo; Cui, Tian; Liu, Zhenxian; Sundqvist, Bertil; Liu, Bingbing

    2015-08-25

    We have studied the structural transformation of Sm@C88 under pressure up to 18 GPa by infrared spectroscopy combined with theoretical simulations. The infrared-active vibrational modes of Sm@C88 at ambient conditions have been assigned for the first time. Pressure-induced blue and red shifts of the corresponding vibrational modes indicate an anisotropic deformation of the carbon cage upon compression. We propose that the carbon cage changes from ellipsoidal to approximately spherical around 7 GPa. A smaller deformation of the carbon bonds in the area close to the Sm atom in the cage suggests that the trapped Sm atom plays a role in minimizing the compression of the adjacent bonds. Pressure induced a significant reduction of the band gap of the crystal. The HOMO-LUMO gap of the Sm@C88 molecule decreases remarkably at 7 GPa as the carbon cage is deformed. Also, compression enhances intermolecular interactions and causes a widening of the energy bands. Both effects decrease the band gap of the sample. The carbon cage deforms significantly above 7 GPa, from spherical to a peanut-like shape and collapses at 18 GPa.

  15. Structural Deformation of Sm@C88 under High Pressure

    PubMed Central

    Cui, Jinxing; Yao, Mingguang; Yang, Hua; Liu, Ziyang; Ma, Fengxian; Li, Quanjun; Liu, Ran; Zou, Bo; Cui, Tian; Liu, Zhenxian; Sundqvist, Bertil; Liu, Bingbing

    2015-01-01

    We have studied the structural transformation of Sm@C88 under pressure up to 18 GPa by infrared spectroscopy combined with theoretical simulations. The infrared-active vibrational modes of Sm@C88 at ambient conditions have been assigned for the first time. Pressure-induced blue and red shifts of the corresponding vibrational modes indicate an anisotropic deformation of the carbon cage upon compression. We propose that the carbon cage changes from ellipsoidal to approximately spherical around 7 GPa. A smaller deformation of the carbon bonds in the area close to the Sm atom in the cage suggests that the trapped Sm atom plays a role in minimizing the compression of the adjacent bonds. Pressure induced a significant reduction of the band gap of the crystal. The HOMO-LUMO gap of the Sm@C88 molecule decreases remarkably at 7 GPa as the carbon cage is deformed. Also, compression enhances intermolecular interactions and causes a widening of the energy bands. Both effects decrease the band gap of the sample. The carbon cage deforms significantly above 7 GPa, from spherical to a peanut-like shape and collapses at 18 GPa. PMID:26303867

  16. Stress-free state of the red blood cell membrane and the deformation of its skeleton.

    PubMed

    Svelc, Tjaša; Svetina, Saša

    2012-06-01

    The response of a red blood cell (RBC) to deformation depends on its membrane, a composite of a lipid bilayer and a skeleton, which is a closed, two-dimensional network of spectrin tetramers as its bonds. The deformation of the skeleton and its lateral redistribution are studied in terms of the RBC resting state for a fixed geometry of the RBC, partially aspirated into a micropipette. The geometry of the RBC skeleton in its initial state is taken to be either two concentric circles, a references biconcave shape or a sphere. It is assumed that in its initial state the skeleton is distributed laterally in a homogeneous manner with its bonds either unstressed, presenting its stress-free state, or prestressed. The lateral distribution was calculated using a variational calculation. It was assumed that the spectrin tetramer bonds exhibit a linear elasticity. The results showed a significant effect of the initial skeleton geometry on its lateral distribution in the deformed state. The proposed model is used to analyze the measurements of skeleton extension ratios by the method of applying two modes of RBC micropipette aspiration.

  17. Effect of high-pressure torsion deformation on surface properties and biocompatibility of Ti-50.9 mol. %Ni alloys.

    PubMed

    Awang Shri, Dayangku Noorfazidah; Tsuchiya, Koichi; Yamamoto, Akiko

    2014-06-01

    Ti-50.9 mol. %Ni was subjected to high-pressure torsion (HPT) deformation for different number of rotations (N) of 0.25, 0.5, 1, 5, and 10. The structural changes induced by HPT were analyzed using x-ray diffractometer (XRD). The surfaces of the samples before and after cell culture were characterized using x-ray photoelectron spectroscopy (XPS). The biocompatibility of the samples was evaluated based on a colony formation assay, nickel ion release, and protein adsorption behavior. XRD analysis revealed the occurrence of grain refinement, phase transformation, and amorphization in the TiNi samples by HPT deformation due to high dislocation density. The changes in chemical composition and thickness of the passive film formed on the surface observed in XPS analysis reveals improvement in the stability of the passive film by HPT deformation. The microstructural change due to the deformation was found to influence the biocompatibility behaviors of TiNi. Plating efficiency and protein adsorption were found to be higher when the samples are in stress-induced martensitic or amorphous state. HPT deformation was found to alter the surface behavior of the TiNi, which effectively reduced the Ni ion release and improved its biocompatibility.

  18. High resolution surface deformation measurements in Iceland's Northern Volcanic Zone: Unraveling multiple deformation sources using InSAR and GPS

    NASA Astrophysics Data System (ADS)

    Spaans, K. H.; Sigmundsson, F.; Hreinsdóttir, S.; Öfeigsson, B. G.

    2012-04-01

    We study crustal deformation in the Krafla and Theistareykir volcanic systems in the Northern Volcanic Zone of Iceland. Krafla experienced a major rifting episode in 1975-1984, and is also the site of a 60 MW geothermal power station. About 20 km to the north-west of Krafla, Theistareykir is mainly known for its geothermal activity, and plans exist to use the area for geothermal energy extraction. Previous studies have shown several deformation signals in the area, including continuous subsidence of the Krafla caldera, intrusive activity in the Theistareykir central volcano and a broad uplift signal to the north of Krafla. Poor spatial and/or temporal resolution in measurements used during previous studies have made it difficult to correctly identify and separate different signals. Here we present results from a combined study of InSAR and GPS data, which yields deformation maps over wide areas around Krafla and Theistareykir with unprecedented resolution. This allows us to not only obtain new constraints on previously identified displacements, but also reveals a subsidence source at Bjarnarflag geothermal field, in the southern part of Krafla's central volcano. We used Interferometric Synthetic Aperture Radar (InSAR) time series analysis covering the period 1992-2010, and over 10 years of Global Positioning System (GPS) measurements in the area. For the InSAR analysis, we applied the StaMPS method to analyse data from the ERS-1/2 and the Envisat missions. This resulted in a relative surface displacement map in the radar line-of-sight (LOS) with high spatial resolution and signal-to-noise ratio. GPS measurements provide highly accurate measurements in three dimensions with respect to an absolute reference frame. Campaign GPS measurements in Krafla and Theistareykir have been performed for over 10 years, with an increasingly dense network of stations. In the fall of 2011, we installed a continuous GPS station in both the Krafla and Theistareykir area to further

  19. Computer Modelling of Cyclic Deformation of High-Temperature Materials

    DTIC Science & Technology

    1993-06-14

    precision. In this case the aim will be at least to eliminate functional empiricism. Restriction of empiricism to the choice of parameters to be input...deformation of dispersion-hardened materials. In the general case this will be done by a literature search. For specific materials, the micromechanisms...cross-slip and/or climb without the generation of appreciable back-stress. Task 112. Anisotropic dispersoids This task covers the case of dispersoids

  20. Lessons from Dynamic Heds: Diagonite Microstructures Suggest Solid-State Deformation, Annealing and Incipient Differentiation

    NASA Astrophysics Data System (ADS)

    Piazolo, S.; Rushmer, T. A.; Luzin, V.

    2014-12-01

    Diagonite meteorites are commonly thought to represent the deep crust or mantle material of Vesta-like bodies. Here, we present textural analysis by neutron diffraction and microstructural and microchemical data on diagonite Yamato 74013. The meteorite is composed mainly of orthopyroxene with inclusions and interstitial grains of troilite and chromite. A coarse grained orthopyroxene - troilite vein transects the sample. Neutron diffraction data shows a distinct crystallographic preferred orientation (CPO) of the orthopyroxene grains. Such strong CPO is unusual for meteorites such as chondrites and stony meteorites. Detailed electron backscatter diffraction analysis confirms that the origin of the preferred orientation is solid state crystal plastic deformation. All phases in the matrix of the rock show crystal plastic deformation, chromite shows distinct substructures, with inclusions of troilite. Orthopyrxone grains are between 50-120 microns in diameter and exhibit irregular interlocking grain boundaries, subgrain boundaries and continuous crystal lattice bending. Grain boundary morphology suggests post-deformation recrystallization with a dominance of grain boundary migration. Orthopyroxene within the vein have traces of S and show straight grain boundaries to each other. Vein troilite grains are interstitial and reach sizes up to 50 times larger than in the matrix. Our results suggest that deep in Yamato's parent body, orthopyroxene is deformed in a crystal plastic regime and experienced significant post-deformational recrystallization. The irregular distribution of interstitial troilite and chromite suggests that segregation of core material has been incipient retaining significant amounts of metal. One possible conclusion is that within small bodies like Vesta, even though deformation and differentiation were concomitant within a dynamic environment, differentiation was not efficient.

  1. Interrogation of living myocardium in multiple static deformation states with diffusion tensor and diffusion spectrum imaging

    PubMed Central

    Lohezic, Maelene; Teh, Irvin; Bollensdorff, Christian; Peyronnet, Rémi; Hales, Patrick W.; Grau, Vicente; Kohl, Peter; Schneider, Jürgen E.

    2014-01-01

    Diffusion tensor magnetic resonance imaging (MRI) reveals valuable insights into tissue histo-anatomy and microstructure, and has steadily gained traction in the cardiac community. Its wider use in small animal cardiac imaging in vivo has been constrained by its extreme sensitivity to motion, exaggerated by the high heart rates usually seen in rodents. Imaging of the isolated heart eliminates respiratory motion and, if conducted on arrested hearts, cardiac pulsation. This serves as an important intermediate step for basic and translational studies. However, investigating the micro-structural basis of cardiac deformation in the same heart requires observations in different deformation states. Here, we illustrate the imaging of isolated rat hearts in three mechanical states mimicking diastole (cardioplegic arrest), left-ventricular (LV) volume overload (cardioplegic arrest plus LV balloon inflation), and peak systole (lithium-induced contracture). An optimised MRI-compatible Langendorff perfusion setup with the radio-frequency (RF) coil integrated into the wet chamber was developed for use in a 9.4T horizontal bore scanner. Signal-to-noise ratio improved significantly, by 75% compared to a previous design with external RF coil, and stability tests showed no significant changes in mean T1, T2 or LV wall thickness over a 170 min period. In contracture, we observed a significant reduction in mean fractional anisotropy from 0.32 ± 0.02 to 0.28 ± 0.02, as well as a significant rightward shift in helix angles with a decrease in the proportion of left-handed fibres, as referring to the locally prevailing cell orientation in the heart, from 24.9% to 23.3%, and an increase in the proportion of right-handed fibres from 25.5% to 28.4%. LV overload, in contrast, gave rise to a decrease in the proportion of left-handed fibres from 24.9% to 21.4% and an increase in the proportion of right-handed fibres from 25.5% to 26.0%. The modified perfusion and coil setup offers

  2. Interrogation of living myocardium in multiple static deformation states with diffusion tensor and diffusion spectrum imaging.

    PubMed

    Lohezic, Maelene; Teh, Irvin; Bollensdorff, Christian; Peyronnet, Rémi; Hales, Patrick W; Grau, Vicente; Kohl, Peter; Schneider, Jürgen E

    2014-08-01

    Diffusion tensor magnetic resonance imaging (MRI) reveals valuable insights into tissue histo-anatomy and microstructure, and has steadily gained traction in the cardiac community. Its wider use in small animal cardiac imaging in vivo has been constrained by its extreme sensitivity to motion, exaggerated by the high heart rates usually seen in rodents. Imaging of the isolated heart eliminates respiratory motion and, if conducted on arrested hearts, cardiac pulsation. This serves as an important intermediate step for basic and translational studies. However, investigating the micro-structural basis of cardiac deformation in the same heart requires observations in different deformation states. Here, we illustrate the imaging of isolated rat hearts in three mechanical states mimicking diastole (cardioplegic arrest), left-ventricular (LV) volume overload (cardioplegic arrest plus LV balloon inflation), and peak systole (lithium-induced contracture). An optimised MRI-compatible Langendorff perfusion setup with the radio-frequency (RF) coil integrated into the wet chamber was developed for use in a 9.4T horizontal bore scanner. Signal-to-noise ratio improved significantly, by 75% compared to a previous design with external RF coil, and stability tests showed no significant changes in mean T1, T2 or LV wall thickness over a 170 min period. In contracture, we observed a significant reduction in mean fractional anisotropy from 0.32 ± 0.02 to 0.28 ± 0.02, as well as a significant rightward shift in helix angles with a decrease in the proportion of left-handed fibres, as referring to the locally prevailing cell orientation in the heart, from 24.9% to 23.3%, and an increase in the proportion of right-handed fibres from 25.5% to 28.4%. LV overload, in contrast, gave rise to a decrease in the proportion of left-handed fibres from 24.9% to 21.4% and an increase in the proportion of right-handed fibres from 25.5% to 26.0%. The modified perfusion and coil setup offers

  3. Microstructural evolution of Ti-added interstitial free steel in high strain deformation by hot torsion

    NASA Astrophysics Data System (ADS)

    Gholizadeh, R.; Shibata, A.; Terada, D.; Tsuji, N.

    2015-08-01

    The dynamically evolved microstructure under high strain deformation condition does still have many debatable aspects, particularly in the case of easy-recovery metals like bcc-iron. In this research, microstructural evolution in high strain deformation by hot torsion of Ti-added interstitial free (IF) steel was systematically investigated. Torsion specimens were deformed up to an equivalent strain of ∼ 7 at different temperatures (650 °C - 850 °C) and strain rates (0.01 s-1 - 1.0 s-1), i.e., under various values of the Zener-Hollomon (Z) parameter. Immediately after the deformation, samples were water-quenched and microstructures were investigated by electron backscattering diffraction (EBSD) measurements and electron channelling contrast imaging (ECCI). Flow stress-strain curves of the IF steel under various deformation conditions showed typical flow curves of high stacking fault energy metals at low Z values, i.e., a peak stress followed by slight softening. On the other hand, under the high-Z deformation conditions, the specimens showed a larger stress drop after a certain amount of deformation. EBSD-based quantitative analysis was used to study the microstructural transition between high and low Z values. At low Z values, the occurrence of strain induced boundary migration (SIBM) as an initiation of dynamic recrystallization (DRX) was clearly observed. On the other hand, at high Z values, grain subdivision phenomena led to very fine and elongated structures.

  4. High incidence of deformity in aquatic turtles in the John Heinz National Wildlife Refuge.

    PubMed

    Bell, Barbara; Spotila, James R; Congdon, Justin

    2006-08-01

    The John Heinz National Wildlife Refuge is subject to pollution from multiple sources. We studied development of snapping turtle (Chelydra serpentina) and painted turtle (Chrysemys picta) embryos from the refuge from 2000 through 2003. Mean annual deformity rate of pooled painted turtle clutches over four years ranged from 45 to 71%, while that of snapping turtle clutches ranged from 13 to 19%. Lethal deformities were more common than minor or moderate deformities in embryos of both species. Adult painted turtles had a higher deformity rate than adult snapping turtles. Snapping turtles at JHNWR had high levels of PAH contamination in their fat. This suggests that PAHs are involved in the high level of deformities. Other contaminants may also play a role. Although the refuge offers many advantages to resident turtle populations, pollution appears to place a developmental burden on the life history of these turtles.

  5. Autowave process of the localized plastic deformation of high-chromium steel saturated with hydrogen

    NASA Astrophysics Data System (ADS)

    Bochkareva, A. V.; Barannikova, S. A.; Li, Yu V.; Lunev, A. G.; Zuev, L. B.

    2016-06-01

    The deformation behavior of high-chromium stainless steel of sorbitic structure upon high-temperature tempering and of electrically saturated with hydrogen in the electrochemical cell during 12 hours is investigated. The stress-strain curves for each state were obtained. From the stress-strain curves, one can conclude that hydrogen markedly reduces the elongation to the fracture of specimen. Using double-exposed speckle photography method it was found that the plastic flow of the material is of a localized character. The pattern distribution of localized plastic flow domains at the linear hardening stage was investigated. Comparative study of autowave parameters was carried out for the tempered steel as well as the electrically saturated with hydrogen steel.

  6. Fetal akinesia deformation sequence in a highly developed acardius twin.

    PubMed

    Konstantinidou, A E; Agapitos, E V; Pavlopoulos, P M; Davaris, P S

    1997-10-01

    We report a case of a holoacardius twin with extremely advanced development of the head, face, upper and lower limbs in the absence of all thoracic and upper abdominal viscera and associated with intestinal and anal atresia. The malformed fetus also had craniofacial abnormalities, hydrops, cystic hygroma of the neck, arthrogryposis and pterygia. The monozygous co-twin was found to be normal. The association of acardia with the typical characteristics of the fetal akinesia deformation sequence has not been previously described in the literature.

  7. Bertram Hopkinson's pioneering work and the dislocation mechanics of high rate deformations and mechanically induced detonations.

    PubMed

    Armstrong, Ronald W

    2014-05-13

    Bertram Hopkinson was prescient in writing of the importance of better measuring, albeit better understanding, the nature of high rate deformation of materials in general and, in particular, of the importance of heat in initiating detonation of explosives. This report deals with these subjects in terms of post-Hopkinson crystal dislocation mechanics applied to high rate deformations, including impact tests, Hopkinson pressure bar results, Zerilli-Armstrong-type constitutive relations, shock-induced deformations, isentropic compression experiments, mechanical initiation of explosive crystals and shear banding in metals.

  8. Electro-hydraulic forming of advanced high-strength steels: Deformation and microstructural characterization

    SciTech Connect

    Rohatgi, Aashish; Stephens, Elizabeth V.; Edwards, Danny J.; Smith, Mark T.; Davies, Richard W.

    2012-06-08

    This conference manuscript describes mechanical and microstructural characterization of steel sheets that were deformed via the electro-hydraulic forming technique. The manuscripts shows the importance of the experimental technique developed at PNNL in the sense that the deformation history information enabled by this technique is not obtainable through existing conventional approaches. Additionally, strain-rate effects on texture development during sheet-forming at high-rates are described. Thus, we have demonstrated that it is now possible to correlate deformation history with microstructural development during high-rate forming, a capability that is unique to PNNL.

  9. Deformation twinning of a silver nanocrystal under high pressure. Supplementary materials

    SciTech Connect

    Huang, X. J.; Yang, W. G.; Harder, R.; Sun, Y.; Lu, M.; Chu, Y. S.; Robinson, I. K.; Mao, H. K.

    2015-10-20

    Within a high-pressure environment, crystal deformation is controlled by complex processes such as dislocation motion, twinning, and phase transitions, which change materials’ microscopic morphology and alter their properties. Likewise, understanding a crystal’s response to external stress provides a unique opportunity for rational tailoring of its functionalities. It is very challenging to track the strain evolution and physical deformation from a single nanoscale crystal under high-pressure stress. Here, we report an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube within a high-pressure environment using the Bragg Coherent Diffractive Imaging (CDI) method. We also observed a continuous lattice distortion, followed by a deformation twining process at a constant pressure. The ability to visualize stress-introduced deformation of nanocrystals with high spatial resolution and prominent strain sensitivity provides an important route for interpreting and engineering novel properties of nanomaterials.

  10. Deformation twinning of a silver nanocrystal under high pressure. Supplementary materials

    DOE PAGES

    Huang, X. J.; Yang, W. G.; Harder, R.; ...

    2015-10-20

    Within a high-pressure environment, crystal deformation is controlled by complex processes such as dislocation motion, twinning, and phase transitions, which change materials’ microscopic morphology and alter their properties. Likewise, understanding a crystal’s response to external stress provides a unique opportunity for rational tailoring of its functionalities. It is very challenging to track the strain evolution and physical deformation from a single nanoscale crystal under high-pressure stress. Here, we report an in situ three-dimensional mapping of morphology and strain evolutions in a single-crystal silver nanocube within a high-pressure environment using the Bragg Coherent Diffractive Imaging (CDI) method. We also observed amore » continuous lattice distortion, followed by a deformation twining process at a constant pressure. The ability to visualize stress-introduced deformation of nanocrystals with high spatial resolution and prominent strain sensitivity provides an important route for interpreting and engineering novel properties of nanomaterials.« less

  11. Texture formation behaviors of Mg-9Al-1Zn alloy during high-temperature compression deformation

    NASA Astrophysics Data System (ADS)

    Park, Minsoo; Okayasu, Kazuto; Fukutomi, Hiroshi; Kim, Kwonhoo

    2016-11-01

    The formation behavior of basal texture during high temperature deformation of AZ91 magnesium alloys in single phase was investigated by plane strain compression deformation. Three kinds of specimens with different initial textures were machined out from a rolled plate having a <0001> texture. The plane strain compression tests were conducted at a temperature of 723 K and a strain of 5.0 × 10-2s-1, with a strain range between -0.4 and -1.0. After deformation, the specimens were immediately quenched in oil. Before deformation, specimen A, {0001} was distributed at the center of pole figure; specimen B shows {0001} was distributed at TD direction; and specimen C, {0001} was distributed at RD direction. Texture evaluation was conducted by Schulz reflection method using nickel-filtered Cu Ka radiation and EBSD. It was found that the main component of texture and the accumulation of pole density vary depending on the deformation condition and the initial texture in all types of specimens. The crystal orientation components in this study were formed by continuous deformation and discontinuous deformation, also when (0001) existed before deformation, an extremely sharp (0001) (compression plane) texture was formed.

  12. High temperature inelastic deformation under uniaxial loading - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Lindholm, U. S.; Bodner, S. R.; Walker, K. P.

    1989-01-01

    The elevated-temperature uniaxial inelastic deformation behavior of an Ni-base alloy, B1900 + Hf, is investigated by performing isothermal tensile, creep, cyclic, stress relaxation, and thermomechanical fatigue tests. The range of strain rates examined is from 10 to the -7th to 100 per sec, while the test temperatures range from 25 to 1093 C. This extensive constitutive data base has been used for evaluating the unified constitutive models of Bodner and Partom (1972) and of Walker (1972) which apply for the small-strain regime. Comparison of test results with independent model predictions indicates good agreement over a broad range of loading conditions, demonstrating the applicability of the unified-constitutive-equation approach for describing the strongly nonlinear and temperature-dependent response of meals under a wide range of deformation and thermal histories. Thus the results give confidence that the unified approach is an effective and efficient approach in which complex history-dependent thermoviscoplastic flow can be represented within a single inelastic strain-rate term.

  13. High temperature inelastic deformation under uniaxial loading - Theory and experiment

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Lindholm, U. S.; Bodner, S. R.; Walker, K. P.

    1989-01-01

    The elevated-temperature uniaxial inelastic deformation behavior of an Ni-base alloy, B1900 + Hf, is investigated by performing isothermal tensile, creep, cyclic, stress relaxation, and thermomechanical fatigue tests. The range of strain rates examined is from 10 to the -7th to 100 per sec, while the test temperatures range from 25 to 1093 C. This extensive constitutive data base has been used for evaluating the unified constitutive models of Bodner and Partom (1972) and of Walker (1972) which apply for the small-strain regime. Comparison of test results with independent model predictions indicates good agreement over a broad range of loading conditions, demonstrating the applicability of the unified-constitutive-equation approach for describing the strongly nonlinear and temperature-dependent response of meals under a wide range of deformation and thermal histories. Thus the results give confidence that the unified approach is an effective and efficient approach in which complex history-dependent thermoviscoplastic flow can be represented within a single inelastic strain-rate term.

  14. Motor Evoked Potentials in 43 High Risk Spine Deformities

    PubMed Central

    Biscevic, Mirza; Biscevic, Sejla; Ljuca, Farid; Smrke, Barbara UR; Ozturk, Cagatay; Tiric-Campara, Merita

    2014-01-01

    ABSTRACT Introduction: Correction of pediatric spine deformities is challenging surgical procedures. This fragile group of patients has many risk factors, therefore prevention of most fearing complication-paraplegia is extremely important. Monitoring of transmission of neurophysiological impulses through motor and sensor pathways of spinal cord gives us an insight into cord's function, and predicts postoperative neurological status. Goal: Aim of this work is to present our experiences in monitoring of spinal cord motor function - MEP during surgical corrections of the hardest pediatric spine deformities, pointing on the most dangerous aspects. Material and methods: We analyzed incidence of MEP changes and postoperative neurological status in patients who had major spine correcting surgery in period April ‘11- April ‘14 on our Spine department. Results: Two of 43 patients or 4.6% in our group experienced significant MEP changes during their major spine reconstructive surgeries. We promptly reduced distractive forces, and MEP normalized, and there were no neurological deficit. Neuromonitoring is reliable method which allows us to “catch” early signs of neurological deficits, when they are still in reversible phase. Although IONM cannot provide complete protection of neurological deficit (it reduces risk of paraplegia about 75%), it at least afford a comfort to the surgeon being fear free that his patient is neurologically intact during long lasting procedures. PMID:25568569

  15. Response of the electron work function to deformation and yielding behavior of copper under different stress states

    NASA Astrophysics Data System (ADS)

    Li, Wen; Wang, Y.; Li, D. Y.

    2004-07-01

    The high sensitivity of the electron work function (EWF) to surface condition has attracted increasing interests from materials scientists and engineers. In this study, using a scanning Kelvin probe changes in the EWF of copper under various loading condition and stress states were investigated. Experimental results showed that the tensile strain decreased the EWF in the elastic deformation range, while compressive strain increased the EWF. However, the EWF in the plastic deformation range always decreased with plastic strain no matter it was tensile or compressive. As shown by the simultaneous measurements of the EWF under conditions of plane stress states, yielding point can be related to the critical stress for the transition of the EWF from smooth variation to steep variation, which strongly depended on stress states. It was therefore demonstrated that Kelvin probing technique could be used for determining the onset of yielding since the EWF was a parameter sensitive to yielding process. The Kelvin probing has appeared to be a very promising method for characterizing the yielding behaviors under complex stress states for both homogeneous and inhomogeneous materials.

  16. High temperature deformation behavior of spray-formed and subsequently extruded Al-25Si based alloy

    NASA Astrophysics Data System (ADS)

    Lee, Sin-Woo; Kim, Mok-Soon

    2016-07-01

    The high temperature deformation behavior of spray-formed and subsequently extruded Al-25Si based alloy containing fine Si and ultra-fine intermetallic phases was examined by compressive tests at temperatures between 523 and 743 K and strain rates between 1.0 × 10-3 and 1.0 × 100/s. The true stress-true strain curves obtained from the compressive tests revealed a peak stress at the initial stage of deformation. The peak stress decreased with increasing temperature or decreasing strain rate. A close relationship was observed between the peak stress and the constitutive equation for high temperature deformation. In the deformed specimens, fine equiaxed grains were observed with a mean grain size of 330 590 nm, which was much finer than that measured prior to deformation (1.4 μm). A dislocation structure within the grains was also observed in the deformed specimens, indicating the occurrence of dynamic recrystallization during high temperature deformation of the present alloy. The occurrence of dynamic recrystallization was also supported by the existence of a peak stress in the flow curve.

  17. Stress and deformation characteristics of sea ice in a high resolution numerical sea ice model.

    NASA Astrophysics Data System (ADS)

    Heorton, Harry; Feltham, Daniel; Tsamados, Michel

    2017-04-01

    The drift and deformation of sea ice floating on the polar oceans is due to the applied wind and ocean currents. The deformations of sea ice over ocean basin length scales have observable patterns; cracks and leads in satellite images and within the velocity fields generated from floe tracking. In a climate sea ice model the deformation of sea ice over ocean basin length scales is modelled using a rheology that represents the relationship between stresses and deformation within the sea ice cover. Here we investigate the link between observable deformation characteristics and the underlying internal sea ice stresses and force balance using the Los Alamos numerical sea ice climate model. In order to mimic laboratory experiments on the deformation of small cubes of sea ice we have developed an idealised square domain that tests the model response at spatial resolutions of up to 500m. We use the Elastic Anisotropic Plastic and Elastic Viscous Plastic rheologies, comparing their stability over varying resolutions and time scales. Sea ice within the domain is forced by idealised winds in order to compare the confinement of wind stresses and internal sea ice stresses. We document the characteristic deformation patterns of convergent, divergent and rotating stress states.

  18. Non-rigid registration of medical images based on estimation of deformation states

    NASA Astrophysics Data System (ADS)

    Marami, Bahram; Sirouspour, Shahin; Capson, David W.

    2014-11-01

    A unified framework for automatic non-rigid 3D-3D and 3D-2D registration of medical images with static and dynamic deformations is proposed in this paper. The problem of non-rigid image registration is approached as a classical state estimation problem using a generic deformation model for the soft tissue. The registration technique employs a dynamic linear elastic continuum mechanics model of the tissue deformation, which is discretized using the finite element method. In the proposed method, the registration is achieved through a Kalman-like filtering process, which incorporates information from the deformation model and a vector of observation prediction errors computed from an intensity-based similarity/distance metric between images. With this formulation, single and multiple-modality, 3D-3D and 3D-2D image registration problems can all be treated within the same framework. The performance of the proposed registration technique was evaluated in a number of different registration scenarios. First, 3D magnetic resonance (MR) images of uncompressed and compressed breast tissue were co-registered. 3D MR images of the uncompressed breast tissue were also registered to a sequence of simulated 2D interventional MR images of the compressed breast. Finally, the registration algorithm was employed to dynamically track a target sub-volume inside the breast tissue during the process of the biopsy needle insertion based on registering pre-insertion 3D MR images to a sequence of real-time simulated 2D interventional MR images. Registration results indicate that the proposed method can be effectively employed for the registration of medical images in image-guided procedures, such as breast biopsy in which the tissue undergoes static and dynamic deformations.

  19. Non-rigid registration of medical images based on estimation of deformation states.

    PubMed

    Marami, Bahram; Sirouspour, Shahin; Capson, David W

    2014-11-21

    A unified framework for automatic non-rigid 3D-3D and 3D-2D registration of medical images with static and dynamic deformations is proposed in this paper. The problem of non-rigid image registration is approached as a classical state estimation problem using a generic deformation model for the soft tissue. The registration technique employs a dynamic linear elastic continuum mechanics model of the tissue deformation, which is discretized using the finite element method. In the proposed method, the registration is achieved through a Kalman-like filtering process, which incorporates information from the deformation model and a vector of observation prediction errors computed from an intensity-based similarity/distance metric between images. With this formulation, single and multiple-modality, 3D-3D and 3D-2D image registration problems can all be treated within the same framework. The performance of the proposed registration technique was evaluated in a number of different registration scenarios. First, 3D magnetic resonance (MR) images of uncompressed and compressed breast tissue were co-registered. 3D MR images of the uncompressed breast tissue were also registered to a sequence of simulated 2D interventional MR images of the compressed breast. Finally, the registration algorithm was employed to dynamically track a target sub-volume inside the breast tissue during the process of the biopsy needle insertion based on registering pre-insertion 3D MR images to a sequence of real-time simulated 2D interventional MR images. Registration results indicate that the proposed method can be effectively employed for the registration of medical images in image-guided procedures, such as breast biopsy in which the tissue undergoes static and dynamic deformations.

  20. High resolution transmission electron microscopic in-situ observations of plastic deformation of compressed nanocrystalline gold

    SciTech Connect

    Wang, Guoyong; Lian, Jianshe; Jiang, Qing; Sun, Sheng; Zhang, Tong-Yi

    2014-09-14

    Nanocrystalline (nc) metals possess extremely high strength, while their capability to deform plastically has been debated for decades. Low ductility has hitherto been considered an intrinsic behavior for most nc metals, due to the lack of five independent slip systems actively operating during deformation in each nanograin. Here we report in situ high resolution transmission electron microscopic (HRTEM) observations of deformation process of nc gold under compression, showing the excellent ductility of individual and aggregate nanograins. Compression causes permanent change in the profile of individual nanograins, which is mediated by dislocation slip and grain rotation. The high rate of grain boundary sliding and large extent of widely exited grain rotation may meet the boundary compatibility requirements during plastic deformation. The in situ HRTEM observations suggest that nc gold is not intrinsically brittle under compressive loading.

  1. High-temperature deformation and microstructural analysis for Si3N4-Sc2O3

    NASA Technical Reports Server (NTRS)

    Cheong, Deock-Soo; Sanders, William A.

    1990-01-01

    It was indicated that Si3N4 doped with Sc2O3 may exhibit high temperature mechanical properties superior to Si3N4 systems with various other oxide sintered additives. High temperature deformation of samples was studied by characterizing the microstructures before and after deformation. It was found that elements of the additive, such as Sc and O, exist in small amounts at very thin grain boundary layers and most of them stay in secondary phases at triple and multiple grain boundary junctions. These secondary phases are devitrified as crystalline Sc2Si2O7. Deformation of the samples was dominated by cavitational processes rather than movements of dislocations. Thus the excellent deformation resistance of the samples at high temperature can be attributed to the very small thickness of the grain boundary layers and the crystalline secondary phase.

  2. Proposed criteria for recognizing intrastratal deformation features in marine high resolution seismic reflection profiles

    USGS Publications Warehouse

    O'Leary, D. W.; Laine, E.

    1996-01-01

    Intrastratal deformation of marine strata is ordinarily recorded in high-resolution seismic reflection profiles as acoustically transparent or "chaotic" intervals marked by hyperbolic echoes. Intrastratal deformation is easily confused with buried slump or slide deposits formed initially at the sea floor. Correct identification of intrastratal deformation depends on the presence of a warped continuously reflective layer overlying a chaotic/transparent layer. Decollement is the key criterion for identification in seismic reflection profiles. Other criteria include intrusive structures or faults rooted in a chaotic/transparent layer and thickening and thinning of a chaotic/transparent layer with transitions to reflective intervals.

  3. High temperature deformation in 2036 Al and 0.2 wt % Zr-2036 A1

    SciTech Connect

    Huang, J.S.; Schwartz, A.J.; Nieh, T.G.

    1995-11-01

    The microstructure and high-temperature deformation of 2036 Al and a 0.2 wt % Zr modified 2036 Al were characterized. A particle-simulated- nucleation process was applied to refine grain structure in both alloys. Thermomechanically processed materials were tested from 450 to 500 C and strain rates from 2{times}10{sup {minus}1} to 2{times}10{sup {minus}4}s{sup {minus}1}. Strain rate sensitivity exponent, activation energy, and total elongation were measured, and the deformation mechanism was proposed. Effect of Zr on microstructure and deformation of 2036 Al at elevated temperatures was discussed.

  4. Laramide thrusting and Tertiary deformation Tierra Caliente, Michoacan and Guerrero States, southwestern Mexico

    SciTech Connect

    Johnson, C.A.; Harrison, C.G.A. ); Lang, H. ); Barros, J.A.; Cabral-Cano, E.

    1990-05-01

    Field investigations and detailed interpretations of Landsat Thematic Mapper images are in progress to improve understanding of regional structure and tectonics of the southernmost extension of the North American cordillera. Two areas have been selected within the Ciudad Altamirano 1:250,000 topographical sheet for geologic mapping and structural interpretation at 1:50,000 scale. The authors results to date require modification of previous ideas concerning the style and timing of deformations, the role and timing of terrane accretion in the overall tectonic history of the region, and the importance of southern Mexico to investigations of the tectonic evolution of the plates in the region. The relative sequence of deformation in the area correlates well with variations in relative motion between North America and plates in the Pacific. Post-Campanian thrusts and generally eastward-verging folds deformed the Mesozoic sequence during the (Laramide equivalent) Hidalgoan orogeny, associated with high-velocity east-west convergence with the Farallon plate that began about 70 Ma. The resulting unconformity was covered by the Tertiary Balsas Formation, a thick sequence of mostly continental clastics. The Tertiary stratigraphy is regionally and sometimes locally variable, but it can be divided into two members. The lower member is relatively volcanic poor and more deformed, and it lies below a regionally significant mid-Tertiary unconformity, which may mark a change to northeast-directed convergence with the Farallon plate sometime prior to 40 Ma. Continued mid-Tertiary deformation in southern Mexico may be related to eastward movement of the Chortis block and the resulting truncation of the Pacific margin of Mexico. The authors also suggest a tentative correlation between the volcaniclastic member of the Lower Cretaceous San Lucas Formation and the protolith of the Roca Verde metamorphics to the east.

  5. Crustal deformation

    NASA Astrophysics Data System (ADS)

    Larson, Kristine M.

    1995-07-01

    Geodetic measurements of crustal deformation provide direct tests of geophysical models which are used to describe the dynamics of the Earth. Although geodetic observations have been made throughout history, only in the last several hundred years have they been sufficiently precise for geophysical studies. In the 19th century, these techniques included leveling and triangulation. Approximately 25 years ago, trilateration measurements were initiated by the USGS (United States Geological Survey) to monitor active faults in the United States. Several years later, NASA (National Aeronautics and Space Administration) begin an effort to measure plate tectonic motions on a global scale, using space geodetic techniques, VLBI (Very Long Baseline Interferometry) and SLR (Satellite Laser Ranging). The period covered by this report to the IUGG, 1991-1994, was a transition period in the field of crustal deformation. Trilateration measurements (previously the backbone of measurements across plate boundaries in the western United States and Alaska) have been abandoned. This system was labor-intensive, involved highly trained crews to carry out the observations, and only measured the length between sites. In addition, NASA drastically cut the budgets for VLBI and SLR during this period. Fixed site VLBI systems are still operational, but mobile VLBI measurements in North America have ceased. SLR measurements continue on a global scale, but the remaining crustal deformation measurements are now being made with the Global Positioning System (GPS). Nonetheless, because of the time scales involved, older geodetic data (including leveling, triangulation, and trilateration) continue to be important for many geophysical studies.

  6. Deformed photon-added entangled squeezed vacuum and one-photon states: Entanglement, polarization, and nonclassical properties

    NASA Astrophysics Data System (ADS)

    A, Karimi; M, K. Tavassoly

    2016-04-01

    In this paper, after a brief review on the entangled squeezed states, we produce a new class of the continuous-variable-type entangled states, namely, deformed photon-added entangled squeezed states. These states are obtained via the iterated action of the f-deformed creation operator A = f (n)a † on the entangled squeezed states. In the continuation, by studying the criteria such as the degree of entanglement, quantum polarization as well as sub-Poissonian photon statistics, the two-mode correlation function, one-mode and two-mode squeezing, we investigate the nonclassical behaviors of the introduced states in detail by choosing a particular f-deformation function. It is revealed that the above-mentioned physical properties can be affected and so may be tuned by justifying the excitation number, after choosing a nonlinearity function. Finally, to generate the introduced states, we propose a theoretical scheme using the nonlinear Jaynes-Cummings model.

  7. Intruder states and the onset of deformation in the neutron-deficient even-even polonium isotopes

    SciTech Connect

    The ISOLDE Collaboration

    1995-12-01

    Alpha- and beta-decay studies of mass-separated Rn and At nuclei reveal the existence of a low-lying 0{sup +} state in {sup 196,198,200,202}Po. The excited 0{sup +} states are interpreted as proton-pair excitations across the {ital Z}=82 shell gap leading to a deformed state, coexisting with the spherical ground state. It is shown that with decreasing neutron number the deformed configuration intrudes to lower excitation energy, increasingly mixing into the ground state. {copyright} {ital 1995 The American Physical Society.}

  8. Numerical study of the stress state of a deformation twin in magnesium

    DOE PAGES

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; ...

    2014-11-26

    Here, we present a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determinedmore » by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.« less

  9. Numerical study of the stress state of a deformation twin in magnesium

    SciTech Connect

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; Lebensohn, R. A.; Tomé, C. N.

    2015-02-01

    We present here a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We have performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determined by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.

  10. Numerical study of the stress state of a deformation twin in magnesium

    SciTech Connect

    Arul Kumar, M.; Kanjarla, A. K.; Niezgoda, S. R.; Lebensohn, R. A.; Tomé, C. N.

    2014-11-26

    Here, we present a numerical study of the distribution of the local stress state associated with deformation twinning in Mg, both inside the twinned domain and in its immediate neighborhood, due to the accommodation of the twinning transformation shear. A full-field elastoviscoplastic formulation based on fast Fourier transformation is modified to include the shear transformation strain associated with deformation twinning. We performed two types of twinning transformation simulations with: (i) the twin completely embedded inside a single crystal and (ii) the twin front terminating at a grain boundary. We show that: (a) the resulting stress distribution is more strongly determined by the shear transformation than by the intragranular character of the twin or the orientation of the neighboring grain; (b) the resolved shear stress on the twin plane along the twin direction is inhomogeneous along the twin–parent interface; and (c) there are substantial differences in the average values of the shear stress in the twin and in the parent grain that contains the twin. We discuss the effect of these local stresses on twin propagation and growth, and the implications of our findings for the modeling of deformation twinning.

  11. Intraplate brittle deformation and states of paleostress constrained by fault kinematics in the central German platform

    NASA Astrophysics Data System (ADS)

    Navabpour, Payman; Malz, Alexander; Kley, Jonas; Siegburg, Melanie; Kasch, Norbert; Ustaszewski, Kamil

    2017-01-01

    The structural evolution of Central Europe reflects contrasting tectonic regimes after the Variscan orogeny during Mesozoic - Cenozoic time. The brittle deformation related to each tectonic regime is localized mainly along major fault zones, creating complex fracture patterns and kinematics through time with diverging interpretations on the number and succession of the causing events. By contrast, fracture patterns in less deformed domains often provide a pristine structural inventory. We investigate the brittle deformation of a relatively stable, wide area of the central German platform using fault-slip data to identify the regional stress fields required to satisfy the data. In a non-classical approach, and in order to avoid local stress variations and misinterpretations, the fault-slip data are scaled up throughout the study area into subsets of consistent kinematics and chronology for sedimentary cover and crystalline basement rocks. Direct stress tensor inversion was performed through an iterative refining process, and the computed stress tensors were verified using field-based observations. Criteria on relative tilt geometry and indicators of kinematic change suggest a succession of events, which begins with a post-Triassic normal faulting regime with σ3 axis trending NE-SW. The deformation then follows by strike-slip and thrust faulting regimes with a change of σ1 axis from N-S to NE-SW, supposedly in the Late Cretaceous. Two younger events are characterized by Cenozoic normal and oblique thrust faulting regimes with NW-SE-trending σ3 and σ1 axes, respectively. The fracture patterns of both the cover and basement rocks appear to record the same states of stress.

  12. Minnesota State High School League.

    ERIC Educational Resources Information Center

    Minnesota State Office of the Legislative Auditor, St. Paul. Program Evaluation Div.

    The Minnesota State High School League administers a program of competitive athletic, musical, speech, and dramatics activities at district, region, and state levels. The league is a voluntary association of 433 public and 49 private schools. This monograph reports on a study of the league in regard to two questions: (1) Are policy-making and…

  13. Non-Gaussian ground-state deformations near a black-hole singularity

    NASA Astrophysics Data System (ADS)

    Hofmann, Stefan; Schneider, Marc

    2017-03-01

    The singularity theorem by Hawking and Penrose qualifies Schwarzschild black holes as geodesic incomplete space-times. Albeit this is a mathematically rigorous statement, it requires an operational framework that allows us to probe the spacelike singularity via a measurement process. Any such framework necessarily has to be based on quantum theory. As a consequence, the notion of classical completeness needs to be adapted to situations where the only adequate description is in terms of quantum fields in dynamical space-times. It is shown that Schwarzschild black holes turn out to be complete when probed by self-interacting quantum fields in the ground state and in excited states. The measure for populating quantum fields on hypersurfaces in the vicinity of the black-hole singularity goes to zero towards the singularity. This statement is robust under non-Gaussian deformations of and excitations relative to the ground state. The physical relevance of different completeness concepts for black holes is discussed.

  14. Constitutive laws for steady state deformation of metals, a microstructural model

    SciTech Connect

    Nes, E.

    1995-07-15

    Based on extensive investigations of the steady state conditions for creep and hot working, Sellars and McG. Tegart demonstrated that the flow stress was well represented by the following relation: {sigma}{sub s} = 1/{alpha}{prime} Arc sinh (Z/A{prime}){sup 1/n} where {alpha}{prime}, A{prime}, n are temperature independent constants and Z is the Zener-Hollomon parameter, Z = {dot {var_epsilon}} exp U/kT, where {dot {var_epsilon}} is the applied strain rate and U is an activation energy. This relationship is widely used in the modelling of metal forming processes such as hot rolling, forging and extrusion. The objective this work is to explore the possibilities for deriving an alternative, physically based, relationship which is capable of correlating the steady state flow stress both to the alloy condition and the microstructural characteristics of steady state deformation.

  15. Identification of deformed intruder states in semi-magic 70Ni

    NASA Astrophysics Data System (ADS)

    Chiara, C. J.; Weisshaar, D.; Janssens, R. V. F.; Tsunoda, Y.; Otsuka, T.; Harker, J. L.; Walters, W. B.; Recchia, F.; Albers, M.; Alcorta, M.; Bader, V. M.; Baugher, T.; Bazin, D.; Berryman, J. S.; Bertone, P. F.; Campbell, C. M.; Carpenter, M. P.; Chen, J.; Crawford, H. L.; David, H. M.; Doherty, D. T.; Gade, A.; Hoffman, C. R.; Honma, M.; Kondev, F. G.; Korichi, A.; Langer, C.; Larson, N.; Lauritsen, T.; Liddick, S. N.; Lunderberg, E.; Macchiavelli, A. O.; Noji, S.; Prokop, C.; Rogers, A. M.; Seweryniak, D.; Shimizu, N.; Stroberg, S. R.; Suchyta, S.; Utsuno, Y.; Williams, S. J.; Wimmer, K.; Zhu, S.

    2015-04-01

    The structure of semi-magic 2870Ni42 was investigated following complementary multinucleon-transfer and secondary fragmentation reactions. Changes to the higher-spin, presumed negative-parity states based on observed γ -ray coincidence relationships result in better agreement with shell-model calculations using effective interactions in the neutron f5 /2p g9 /2 model space. The second 2+ and (4+) states, however, can only be successfully described when proton excitations across the Z =28 shell gap are included. Monte Carlo shell-model calculations suggest that the latter two states are part of a prolate-deformed intruder sequence, establishing an instance of shape coexistence at low excitation energies similar to that observed recently in neighboring 68Ni.

  16. Non-proportional/Non-monotonous Deformation Modeling of an Ultra High Strength Automotive Steel Sheet

    NASA Astrophysics Data System (ADS)

    Verma, Rahul K.; Ogihara, Yuki; Kuwabara, Toshihiko; Chung, Kwansoo

    2011-08-01

    In this work, as non-proportional/non-monotonous deformation experiments, two-stage and tension-compression-tension uniaxial tests were performed, respectively, for a cold rolled ultra high strength dual phase steel sheet: DP780. Deformation behaviors under such deformation paths were found different than those of the ultra low carbon single phase steels observed by Verma et al. (Int. J. Plast. 2011, 82-101). To model the newly observed deformation behaviors, the combined type constitutive law previously proposed by Verma et al. (Int. J. Plast. 2011, 82-101) was successfully applied here. Permanent softening observed during reverse loading was properly characterized into the isotropic and kinematic hardening parts of the hardening law using tension-compression-tension test data. The cross effect observed in two-stage tests was also effectively incorporated into the constitutive law.

  17. High power solid state lasers

    SciTech Connect

    Weber, H.

    1988-01-01

    These proceedings discuss the following subjects: trends in materials processing with laser radiation; slabs and high power systems; glasses and new crystals; solid state lasers at HOYA Corp.; lamps, resonators and transmission; glasses as active materials for high average power solid state lasers; flashlamp pumped GGG-crystals; alexandrite lasers; designing telescope resonators; mode operation of neodymium: YAG lasers; intracavity frequency doubling with KTP crystal and thermal effects in cylinder lasers.

  18. High-K structure in {sup 250}Fm and the deformed shell gaps at N=152 and Z=100

    SciTech Connect

    Greenlees, P. T.; Ketelhut, S.; Grahn, T.; Jones, P.; Julin, R.; Juutinen, S.; Leino, M.; Nyman, M.; Rahkila, P.; Saren, J.; Scholey, C.; Sorri, J.; Uusitalo, J.; Herzberg, R.-D.; Butler, P. A.; Gray-Jones, C.; Jones, G. D.; Moon, S.; Pakarinen, J.; Rostron, D.

    2008-08-15

    The structure of high-spin and nonyrast states of the transfermium nucleus {sup 250}Fm has been studied in detail. The isomeric nature of a two-quasiparticle excitation has been exploited in order to obtain spectroscopic data of exceptional quality. The data allow the configuration of an isomer first discovered over 30 years ago to be deduced, and provide an unambiguous determination of the location of neutron single-particle states in a very heavy nucleus. A comparison to the known two-quasiparticle structure of {sup 254,252}No confirms the existence of the deformed shell gaps at N=152 and Z=100.

  19. Development of rotational diamond anvil cell for ultra-high pressure deformation experiments

    NASA Astrophysics Data System (ADS)

    Azuma, S.; Nomura, R.; Nakashima, Y.; Uesugi, K.; Shinmei, T.; Irifune, T.

    2016-12-01

    Development of high-pressure (static compression) experiments using a diamond anvil cell (DAC) enabled to increase pressure up to 360 GPa, corresponding conditions to inner core of the Earth (e.g., Tateno et al., 2010). On the other hand, pressure range is limited for a technical reason in high-pressure deformation experiments. Earth's interior is dominated by `dynamic' processes. Therefore, expansion of pressure range in deformation experiments is necessary to understanding the evolution of Earth's deep interior. We developed rotational diamond anvil cell (R-DAC) to conduct deformation experiments with large strain under ultra-high pressure conditions, corresponding to those of Earth's core. In this study, existing DAC is modified to give torsional deformation to sample. In the developed R-DAC, lower anvil is fixed and upper anvil can rotate to relative to the lower anvil. We deformed MgO to test this apparatus. The experimental conditions are ranging 30-135 GPa and room temperature. Starting material was grooved by FIB and the groove was deposited by Pt as strain-marker. Recovered samples were cut by FIB to observe the rotation angle of strain-marker, sample thickness, and shape of strain-marker in each cross-section. Deformation experiments were conducted also in Japan Synchrotron Radiation Research Institute (SPring-8) and 3D visualization of the internal structure of samples were performed using X-ray laminography (Nomura and Uesugi, 2016). We succeeded the deformation experiment at 135 GPa. The geometry of strain-marker in recovered samples show nearly simple shear, indicating that this apparatus allows us to investigate the deformation with large strain under ultra-high pressure conditions, corresponding to those of core-mantle boundary. The rotation angle of strain-marker in recovered samples were compared to that expected from rotation angle of upper anvil. The results show relatively good agreement, indicating no large slip between upper anvil and samples

  20. Elastic registration of prostate MR images based on estimation of deformation states.

    PubMed

    Marami, Bahram; Sirouspour, Shahin; Ghoul, Suha; Cepek, Jeremy; Davidson, Sean R H; Capson, David W; Trachtenberg, John; Fenster, Aaron

    2015-04-01

    Magnetic resonance imaging (MRI) is being used increasingly for image-guided targeted biopsy and focal therapy of prostate cancer. In this paper, a combined rigid and deformable registration technique is proposed to register pre-treatment diagnostic 3T magnetic resonance (MR) images of the prostate, with the identified target tumor(s), to intra-treatment 1.5T MR images. The pre-treatment T2-weighted MR images were acquired with patients in a supine position using an endorectal coil in a 3T scanner, while the intra-treatment T2-weighted MR images were acquired in a 1.5T scanner before insertion of the needle with patients in the semi-lithotomy position. Both the rigid and deformable registration algorithms employ an intensity-based distance metric defined based on the modality independent neighborhood descriptors (MIND) between images. The optimization routine for estimating the rigid transformation parameters is initialized using four pairs of manually selected approximate corresponding points on the boundaries of the prostate. In this paper, the problem of deformable image registration is approached from the perspective of state estimation for dynamical systems. The registration algorithm employs a rather generic dynamic linear elastic model of the tissue deformation discretized by the finite element method (FEM). We use the model in a classical state estimation framework to estimate the deformation of the prostate based on the distance metric between pre- and intra-treatment images. Our deformable registration results using 17 sets of prostate MR images showed that the proposed method yielded a target registration error (TRE) of 1.87 ± 0.94 mm,2.03 ± 0.94 mm, and 1.70 ± 0.93 mm for the whole gland (WG), central gland (CG), and peripheral zone (PZ), respectively, using 76 manually-identified fiducial points. This was an improvement over the 2.67 ± 1.31 mm, 2.95 ± 1.43 mm, and 2.34 ± 1.11 mm, respectively for the WG, CG, and PZ after rigid registration alone

  1. Subsurface deformation along major thrusts in the outer-arc high off northwest Sumatra

    NASA Astrophysics Data System (ADS)

    Misawa, A.; Hirata, K.; Seeber, L.; Arai, K.; Ashi, J.; Rahardiawan, R.; Udrekh, U.; Baba, H.; Kinoshita, M.; Fujiwara, T.; Tokuyama, H.; Nakamura, Y.; Permana, H.; Djajadihardja, Y. S.

    2012-12-01

    A huge ocean-wide tsunami, with average heights of more than 20 meters along the west coast of the northern tip of Sumatra followed the 2004 Sumatra-Andaman earthquake (Mw9.2). Several working hypotheses have been proposed, but the generation mechanism for this tsunami remains unresolved. Several hypotheses suggest a possible coseismic slip on splay faults in the outer-arc-high off northwest Sumatra [e.g., Sibuet et al., 2007]. Among these splay faults, the Middle Thrust(MT) (or possibly the Lower Thrust(LT)), can best account for features of the Indian Ocean tsunamis observed at regional and ocean-wide distances [Hirata et al., 2008]. In 2009, we conducted KY09-09 bathymetry survey offshore northern Sumatra and recognized many geological structures, including candidate traces of these splay faults in the outer-arc-high. In 2010, we conducted the KH-10-5 high-resolution MCS survey with a total of 18 seismic lines to image the subsurface structure associated with LT, MT, and the Upper Thrust(UT) in the outer-arc high. Many of subsurface deformations that can be identified on MCS profiles are distributed along these major thrusts. For an example, more than ten of these MCS profiles show clear indication of subsurface deformation along MT. However, a fraction of subsurface deformations are distributed along other large faults existing between these major thrusts. 14 MCS lines cross basins adjoining MT. Several of these MCS profiles show that the uppermost sediment layers of the basins are deformed, either progressively tilted up to a horizontal sea floor, or sub-parallel tilted along with the sea floor. This suggests geologically "recent" deformation associated with slip along MT. However, other MCS lines did not image such a clear "recent" deformation structures near MT. This may imply lack of deformation, or lack of recent sediment along these profiles to record the deformation. Three MCS lines cross UT of Sibuet et al.[2007] or neighboring basins but we could not

  2. Mixed brittle-plastic deformation behaviour in a slate belt. Examples from the High-Ardenne slate belt (Belgium, Germany)

    NASA Astrophysics Data System (ADS)

    Sintubin, Manuel; van Baelen, Hervé; van Noten, Koen; Muchez, Philippe

    2010-05-01

    again a blocky infill. The detachments reflect the late orogenic destabilisation of the slate belt, again suggesting vein development related to a tectonic inversion (from compression to extension). A kinematic model is developed in which brittle parental cracks are affected by a steady-state solid-state deformation within a creeping shear zone and evolve as plastically deforming fluid-filled cavities. Also this type of quartz veins reflects mixed brittle-plastic deformation behaviour in mid-crustal conditions. Both types of quartz vein demonstrate that fluid-assisted, mixed brittle-plastic deformation in a developing slate belt is strongly related to major changes in the overall stress regime. Both during the tectonic inversion in the earliest and late stages of the Variscan orogeny extensive veining occurred. This is in contrast to the main compression stage of the orogeny, during which vein development seems rather occasional. While the late orogenic vein occurrence can be linked directly to a mid-crustal detachment root of an upper-crustal fault system, the regional aspect of the early orogenic veins remains enigmatic. In both cases a transient strain-rate dependent deepening of the brittle-plastic transition is proposed to explain the formation of the brittle parental cracks. The plastic deformation of the fluid-filled cavities may be related to a recovery of the long-term brittle-plastic transition. The former deepening may thus be related to coseismic loading of the middle crust, while the latter recovery may reflect the postseismic relaxation. In this respect the different types of mixed brittle-plastic vein structures observed in the High-Ardenne slate belt may be seen as a reflection of earthquake-related deformation and fluid redistribution in the middle crust.

  3. Microstructures and Mechanical Properties of High-Mn TRIP Steel Based on Warm Deformation of Martensite

    NASA Astrophysics Data System (ADS)

    Guo, Zhikai; Li, Longfei; Yang, Wangyue; Sun, Zuqing

    2015-04-01

    High-Mn TRIP steel with about 5 wt pct Mn was prepared by a thermo-mechanical treatment based on warm deformation of martensite and subsequent short-time annealing in the intercritical region. The microstructural evolution and the mechanical properties of the used steel during such treatment were investigated. The results indicate that during warm deformation of martensite in the intercritical region, the decomposition of martensite was accelerated by warm deformation and the occurrence of dynamic recrystallization of ferrite led to the formation of equiaxed ferrite grains. Meanwhile, the reverse transformation of austenite was accelerated by warm deformation to some extent. During subsequent annealing in the intercritical region, static recrystallization of ferrite led to the increase in the fraction of equiaxed ferrite grains, and the formation of the reversed austenite was accelerated by the addition of the deformation-stored energy, while the stability of the reversed austenite was improved by the accelerated diffusions of C atoms and Mn atoms. As a whole, the mechanical properties of the used steel by the thermo-mechanical treatment based on warm deformation of martensite and subsequent short-time annealing in the intercritical region were comparable to the steels with similar compositions subjected to intercritical annealing for hours after cold rolling of martensite.

  4. High-Resolution Adaptive Optics Scanning Laser Ophthalmoscope with Dual Deformable Mirrors

    SciTech Connect

    Chen, D C; Jones, S M; Silva, D A; Olivier, S S

    2006-08-11

    Adaptive optics scanning laser ophthalmoscope (AO SLO) has demonstrated superior optical quality of non-invasive view of the living retina, but with limited capability of aberration compensation. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina. We used a bimorph mirror to correct large-stroke, low-order aberrations and a MEMS mirror to correct low-stroke, high-order aberration. The measured ocular RMS wavefront error of a test subject was 240 nm without AO compensation. We were able to reduce the RMS wavefront error to 90 nm in clinical settings using one deformable mirror for the phase compensation and further reduced the wavefront error to 48 nm using two deformable mirrors. Compared with that of a single-deformable-mirror SLO system, dual AO SLO offers much improved dynamic range and better correction of the wavefront aberrations. The use of large-stroke deformable mirrors provided the system with the capability of axial sectioning different layers of the retina. We have achieved diffraction-limited in-vivo retinal images of targeted retinal layers such as photoreceptor layer, blood vessel layer and nerve fiber layers with the combined phase compensation of the two deformable mirrors in the AO SLO.

  5. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 1; Matrix Constitutive Equations

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this first paper of a two part report, background information is presented, along with the constitutive equations which will be used to model the rate dependent nonlinear deformation response of the polymer matrix. Strain rate dependent inelastic constitutive models which were originally developed to model the viscoplastic deformation of metals have been adapted to model the nonlinear viscoelastic deformation of polymers. The modified equations were correlated by analyzing the tensile/ compressive response of both 977-2 toughened epoxy matrix and PEEK thermoplastic matrix over a variety of strain rates. For the cases examined, the modified constitutive equations appear to do an adequate job of modeling the polymer deformation response. A second follow-up paper will describe the implementation of the polymer deformation model into a composite micromechanical model, to allow for the modeling of the nonlinear, rate dependent deformation response of polymer matrix composites.

  6. Effect of stress states on the deformation behavior of Cu-based bulk metallic glass in the supercooled liquid region

    SciTech Connect

    Park, Eun Soo; Kim, Hyong June; Bae, J. C.; Huh, M. Y.

    2013-01-24

    The effect of stress states on the deformation behavior of the Cu54Zr22Ti18Ni6 bulk metallic glass (BMG) alloy was studied in the supercooled liquid region. At 723 K, Newtonian plastic flow governed the deformation during the compression test, whereas strain-hardening occurred during the tensile test. At 733 K, a fast failure was observed during tensile test. The diffusion rate of Cu atoms in the BMG alloy plays an important role in the deformation behavior. The fast diffusion of Cu atoms under the tensile stress state caused faster crystallization leading to a fast strain-hardening during the tensile plastic deformation. Published by Elsevier B.V.

  7. The FEM Simulation Of Cementite Lamellas Deformation In Pearlitic Colony During Drawing Of High Carbon Steel

    NASA Astrophysics Data System (ADS)

    Milenin, Andriy; Muskalski, Z.

    2007-05-01

    In paper the wire drawing processes was investigated in two levels — steady-state solve using the 2-dimensional rigid-plastic finite element method (macro-level) and modeling of a microstructure change (micro-level). In macro level the joint deformation-temperature problem was considered. In micro-level the process of deformation of representative volume element — RVE was considered. The pearlitic colony deformation and orientation of cementite lamellas change in RVE was modeled with help of a FEM. The micro-level model to rigid-plastic finite element code was implemented. The experimental data of microstructure and orientation of cementite lamellas change was compared with results of a simulations. The influence of multi-pass drawing parameters (as friction, drawing schedule) on orientation of cementite lamellas was investigated.

  8. The FEM Simulation Of Cementite Lamellas Deformation In Pearlitic Colony During Drawing Of High Carbon Steel

    SciTech Connect

    Milenin, Andriy; Muskalski, Z.

    2007-05-17

    In paper the wire drawing processes was investigated in two levels - steady-state solve using the 2-dimensional rigid-plastic finite element method (macro-level) and modeling of a microstructure change (micro-level). In macro level the joint deformation-temperature problem was considered. In micro-level the process of deformation of representative volume element - RVE was considered. The pearlitic colony deformation and orientation of cementite lamellas change in RVE was modeled with help of a FEM. The micro-level model to rigid-plastic finite element code was implemented. The experimental data of microstructure and orientation of cementite lamellas change was compared with results of a simulations. The influence of multi-pass drawing parameters (as friction, drawing schedule) on orientation of cementite lamellas was investigated.

  9. Texture Development in High-Silicon Iron Sheet Produced by Simple Shear Deformation

    NASA Astrophysics Data System (ADS)

    Kustas, Andrew B.; Sagapuram, Dinakar; Trumble, Kevin P.; Chandrasekar, Srinivasan

    2016-06-01

    Sheet processing of high Si-Fe alloys (up to 6.5 wt pct Si) is demonstrated by application of highly confined shear deformation in cutting-extrusion. This alloy system, of major interest to electromagnetic applications, is characterized by poor workability. By a suitable interactive combination of simple shear, high strain rates, near-adiabatic heating, and large hydrostatic pressure in the deformation zone, flow localization, and cracking inherent to this alloy system are suppressed. This enables creation of sheet and foil forms from bulk ingots, cast or wrought, in a single deformation step, unlike rolling. The sheet is characterized by strong shear textures, described by partial {110} and <111> fibers, and fine-grained microstructures ( 20 µm grain size). The orientation (inclination) of these fibers, with respect to the sheet surface, can be varied over a range of 35 deg through selection of the deformation path. In contrast to rolling textures, the current shear deformation textures are negligibly influenced by recrystallization annealing. A recovery-based continuous recrystallization mechanism is proposed to explain the texture retention. Some general implications for shear-based processing of alloys of limited workability are discussed.

  10. Cryogenic deformation of high temperature superconductive composite structures

    DOEpatents

    Roberts, Peter R.; Michels, William; Bingert, John F.

    2001-01-01

    An improvement in a process of preparing a composite high temperature oxide superconductive wire is provided and involves conducting at least one cross-sectional reduction step in the processing preparation of the wire at sub-ambient temperatures.

  11. High-temperature deformation of Sr(FeCo){sub 1.5}O{sub x} ceramics.

    SciTech Connect

    de Arellano-Lopez, A. R.; Balachandran, U.; Goretta, K. C.; Ma, B.; Routbort, J. L.; Energy Technology; Univ. de Sevilla

    2001-01-01

    Compressive creep of polycrystalline SrFe{sub 1.2}Co{sub 0.3}O{sub x} and SrFeCo{sub 0.5}O{sub x} ceramics has been investigated at 940-1000 C in constant-load and constant-displacement-rate experiments. At low stresses, the stress exponent was {approx}1 and the activation energy was {approx}110-135 kJ/mol. At higher stresses, a transition occurred and the stress exponent became {approx}2.4-3.1 and the activation energy became {approx}425-453 kJ/mol. At higher stresses, there was no dependence of the steady-state flow stress on oxygen partial pressure from 10-10{sup 5} Pa. The creep parameters and scanning and transmission electron microscopy observations of the deformed samples suggested that deformation was controlled by diffusion at low stresses and dislocation glide at high stresses.

  12. High-speed measurements of steel-plate deformations during laser surface processing.

    PubMed

    Jezersek, Matija; Gruden, Valter; Mozina, Janez

    2004-10-04

    In this paper we present a novel approach to monitoring the deformations of a steel plate's surface during various types of laser processing, e.g., engraving, marking, cutting, bending, and welding. The measuring system is based on a laser triangulation principle, where the laser projector generates multiple lines simultaneously. This enables us to measure the shape of the surface with a high sampling rate (80 Hz with our camera) and high accuracy (+/-7 microm). The measurements of steel-plate deformations for plates of different thickness and with different illumination patterns are presented graphically and in an animation.

  13. On the High Temperature Deformation Behaviour of 2507 Super Duplex Stainless Steel

    NASA Astrophysics Data System (ADS)

    Mishra, M. K.; Balasundar, I.; Rao, A. G.; Kashyap, B. P.; Prabhu, N.

    2017-02-01

    High temperature deformation behaviour of 2507 super duplex stainless steel was investigated by conducting isothermal hot compression tests. The dominant restoration processes in ferrite and austenite phases present in the material were found to be distinct. The possible causes for these differences are discussed. Based on the dynamic materials model, processing map was developed to identify the optimum processing parameters. The microstructural mechanisms operating in the material were identified. A unified strain-compensated constitutive equation was established to describe the high temperature deformation behaviour of the material under the identified processing conditions. Standard statistical parameter such as correlation coefficient has been used to validate the established equation.

  14. Can the multianvil apparatus really be used for high-pressure deformation experiments?

    SciTech Connect

    Durham, W.B.; Rubie, D.C.

    1996-04-24

    Past claims of the suitability of the MA-8 multianvil press as a deformation apparatus may have been overstated. On the basis of measurements of final octahedron size and of guide block displacement as a function of time, using the 10/5, 14/8, and 18/11 assemblies (octahedron edge length in mm/truncation edge length in mm) with MgO octahedra and pyrophyllite gasketing, it appears that at run conditions of interest to most researchers there is no appreciable time-dependent creep of gaskets and octahedra. All inelastic deformation occurs at rather low pressures: below about 10 GPa for the 10/5, 7 GPa for the 14/8, and 6 GPa for the 18/11 assemblies, with substantial uncertainties in these pressures. Above these limits all deformation of the pressure medium is elastic. Pressure stepping as a means of increasing the inelastic deformation rate of a sample is probably ineffective. Displacement measured at the guide blocks, previously believed to indicate deformation of the gaskets and octahedron, appears now to be unrelated to creep of these components. The calibrations have not been exhaustive and there is considerable scatter in some of the size measurements, so the above conclusions are not unequivocal. The calibrations do not exclude the possibility of deformation of a few tens of microns after the attainment of high pressure. Efforts to impose permanent shape change to samples at high pressure and temperature simply by relying on long run durations must be viewed with skepticism. There may be possibilities for deformation in the multianvil apparatus if materials of contrasting elastic modulus are used to differentially load a sample during pressure stepping.

  15. Development of high-order segmented MEMS deformable mirrors

    NASA Astrophysics Data System (ADS)

    Helmbrecht, Michael A.; He, Min; Kempf, Carl J.

    2012-03-01

    The areas of biological microscopy, ophthalmic research, and atmospheric turbulence correction require high-order DMs to obtain diffraction-limited images. Iris AO has been developing high-order MEMS DMs to address these requirements. Recent development has resulted in fully functional 489-actuator DMs capable of 9.5 µm stroke. For laser applications, the DMs were modified to make them compatible with high-reflectance dielectric coatings. Experimental results for the 489-actuator DMs with dielectric coatings shows they can be made with superb optical quality λ/93.3 rms (11.4 nm rms) and λ/75.9 rms (20.3 nm rms) for 1064 nm and 1540 nm coatings. Laser testing has demonstrated 300 W/cm2 power handling with off-the-shelf packaging. Power handling of 2800 W/cm2 is projected when incorporating packaging optimized for heat transfer.

  16. Influence of Stress State, Stress Orientation, and Rock Properties on the Development of Deformation-Band 'Ladder' Arrays in Porous Sandstone

    NASA Astrophysics Data System (ADS)

    Schultz, R. A.; Soliva, R.; Fossen, H.

    2013-12-01

    Deformation bands in porous rocks tend to develop into spatially organized arrays that display a variety of lengths and thicknesses, and their geometries and arrangements are of interest with respect to fluid flow in reservoirs. Field examples of deformation band arrays in layered clastic sequences suggest that the development of classic deformation band arrays, such as ladders and conjugate sets, and the secondary formation of through-going faults appear to be related to the physical properties of the host rock, the orientation of stratigraphic layers relative to the far-field stress state, and the evolution of the local stress state within the developing array. We have identified several field examples that demonstrate changes in band properties, such as type and orientation, as a function of one or more of these three main factors. Normal-sense deformation-band arrays such as those near the San Rafael Swell (Utah) develop three-dimensional ladder-style arrays at a high angle to the maximum compression direction; these cataclastic shear bands form at acute angles to the maximum compression not very different from that of the optimum frictional sliding plane, thus facilitating the eventual nucleation of a through-going fault. At Orange quarry (France), geometrically conjugate sets of reverse-sense compactional shear bands form with angles to the maximum compression direction that inhibit fault nucleation within them; the bands in this case also form at steep enough angles to bedding that stratigraphic heterogeneities within the deforming formation were apparently not important. Two exposures of thrust-sense ladders at Buckskin Gulch (Utah) demonstrate the importance of host-rock properties, bedding-plane involvement, and local stress perturbations on band-array growth. In one ladder, thrust-sense shear deformation bands nucleated along suitably oriented bedding planes, creating overprinting sets of compaction bands that can be attributed to layer properties and

  17. The Effect of Anhydrous Ammonia on the Crystalline State Deformation of Nylons 6 and 6,6.

    DTIC Science & Technology

    1981-09-14

    for Public Release; Distribution Unlimited !1 82t 01 11 057 THE EFFECT OF ANHYDROUS AMONIA ON THE CRYSTALLINE STATE DEFORMATION OF NYLONS 6 AND 6,6 by...7 AD-A109 62 MASSACHUSETTS UWIV AMHERST DEPT OF POLYMER SCIENCE -ETC FIG 11/9 THE EFFECT OF ANHYDROUS AMMONIA ON THE CRYSTALLINE STATE DFORN-ETC(U...REPORT NO. 15 "THE EFFECT OF ANHYDROUS AMMONIA ON THE CRYSTALLINE STATE DEFORMATION OF NYLONS 6 AND 6,6" by Tetsuo Kanamoto, Anagnostis E. Zachariades

  18. Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

    DOE PAGES

    Wang, Xueju; Pan, Zhipeng; Fan, Feifei; ...

    2015-09-10

    We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for themore » analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.« less

  19. Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

    SciTech Connect

    Wang, Xueju; Pan, Zhipeng; Fan, Feifei; Wang, Jiangwei; Liu, Yang; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-09-10

    We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for the analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.

  20. High Actuator Count MEMS Deformable Mirrors for Space Telescopes

    DTIC Science & Technology

    2010-06-07

    Astronomy – Direct Planet Detection • High Contrast Imaging – Astronomy/Reconnaissance • Correction of surface figure errors in Light weight primary mirrors...NASA’s TPF Coronagraphic Imaging Observatory EPIC PECO Extrasolar Planetary Imaging Coronagraph Pupil-mapping Exoplanet Coronagraphic Observer Why

  1. High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

    SciTech Connect

    Chen, D; Jones, S M; Silva, D A; Olivier, S S

    2007-01-25

    Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 {micro}m stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 {micro}m stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to {+-} 3D of defocus and {+-} 3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large phase compensation can eliminate accurate refractive error fitting for the patients, which greatly improves the system ease of use and efficiency in the clinical environment.

  2. Integrated optical design for highly dynamic laser beam shaping with membrane deformable mirrors

    NASA Astrophysics Data System (ADS)

    Pütsch, Oliver; Stollenwerk, Jochen; Loosen, Peter

    2017-02-01

    The utilization of membrane deformable mirrors has raised its importance in laser materials processing since they enable the generation of highly spatial and temporal dynamic intensity distributions for a wide field of applications. To take full advantage of these devices for beam shaping, the huge amount of degrees of freedom has to be considered and optimized already within the early stage of the optical design. Since the functionality of commercial available ray-tracing software has been mainly specialized on geometric dependencies and their optimization within constraints, the complex system characteristics of deformable mirrors cannot be sufficiently taken into account yet. The main reasons are the electromechanical interdependencies of electrostatic membrane deformable mirrors, namely saturation and mechanical clamping, that result in non-linear deformation. This motivates the development of an integrative design methodology. The functionality of the ray-tracing program ZEMAX is extended with a model of an electrostatic membrane mirror. This model is based on experimentally determined influence functions. Furthermore, software routines are derived and integrated that allow for the compilation of optimization criteria for the most relevant analytically describable beam shaping problems. In this way, internal optimization routines can be applied for computing the appropriate membrane deflection of the deformable mirror as well as for the parametrization of static optical components. The experimental verification of simulated intensity distributions demonstrates that the beam shaping properties can be predicted with a high degree of reliability and precision.

  3. Concept and modeling analysis of a high fidelity multimode deformable mirror.

    PubMed

    Zhou, Chao; Li, Yun; Wang, Anding; Xing, Tingwen

    2015-06-10

    Conventional deformable mirrors (DM) cannot meet the requirement of aberration controlling for advanced lithography tools. This paper illustrates an approach using the property that deformation of a thin plate is similar to optical modes to realize a high fidelity multimode deformable mirror whose deformation has characteristics of optical aberration modes. The way to arrange actuators is also examined. In this paper, a 36-actuator deformable mirror is taken as an example to generate low-order Zernike modes. The result shows that this DM generates the fourth fringe Zernike mode (Z4) defocus, and primary aberration Z5-Z8 with an error less than 0.5%, generates the fifth-order aberration Z10-Z14, and generates the seventh-order aberration Z17-Z20 with an error less than 1.1%. The high fidelity replication of the Zernike mode indicates that the DM satisfies the demand of controlling aberrations corresponding to the first 20 Zernike modes in an advanced lithography tool.

  4. Friction properties and deformation mechanisms of halite(-mica) gouges from low to high sliding velocities

    NASA Astrophysics Data System (ADS)

    Buijze, Loes; Niemeijer, André R.; Han, Raehee; Shimamoto, Toshihiko; Spiers, Christopher J.

    2017-01-01

    The evolution of friction as a function of slip rate is important in understanding earthquake nucleation and propagation. Many laboratory experiments investigating friction of fault rocks are either conducted in the low velocity regime (10-8-10-4 ms-1) or in the high velocity regime (0.01-1 m s-1). Here, we report on the evolution of friction and corresponding operating deformation mechanisms in analog gouges deformed from low to high slip rates, bridging the gap between these low and high velocity regimes. We used halite and halite-muscovite gouges to simulate processes, governing friction, active in upper crustal quartzitic fault rocks, at conditions accessible in the laboratory. The gouges were deformed over a 7 orders of magnitude range of slip rate (10-7-1 m s-1) using a low-to-high velocity rotary shear apparatus, using a normal stress of 5 MPa and room-dry humidity. Microstructural analysis was conducted to study the deformation mechanisms. Four frictional regimes as a function of slip rate could be recognized from the mechanical data, showing a transitional regime and stable sliding (10-7-10-6 m s-1), unstable sliding and weakening (10-6-10-3 m s-1), hardening (10-2-10-1 m s-1) and strong weakening (10-1-1 m s-1). Each of the four regimes can be associated with a distinct microstructure, reflecting a transition from mainly brittle deformation accompanied by pressure solution healing to temperature activated deformation mechanisms. Additionally, the frictional response of a sliding gouge to a sudden acceleration of slip rate to seismic velocities was investigated. These showed an initial strengthening, the amount of which depended on the friction level at which the step was made, followed by strong slip weakening.

  5. The Deformability of a High Performance Concrete (HPC)

    NASA Astrophysics Data System (ADS)

    Benamara, Dalila; Mezghiche, Bouzidi; Zohra, Mechrouh Fatma

    The current tendency in the world is to find new materials at lower cost which can guarantee better performances during their incorporations in the concretes. Our study lies within the scope of the valorization of local materials. Among these materials we find the high performance concrete, which has become the object of the several researchers for a few years. This study consists the development and the mechanical and elastic properties of a concrete with high performances (HPC) starting from materials existing on the Algerian market. Three mineral additions: limestone, the sand of dune and the waste of polishing of tiling are incorporated a cement with various contents (5%, 10%, 15% and 20%). instead of the fume of silica or fly-ashes.

  6. Butterflies' wings deformations using high speed digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Mendoza Santoyo, Fernando; Aguayo, Daniel D.; de La Torre-Ibarra, Manuel H.; Salas-Araiza, Manuel D.

    2011-08-01

    A variety of efforts in different scientific disciplines have tried to mimic the insect's in-flight complex system. The gained knowledge has been applied to improve the performance of different flying artifacts. In this research report it is presented a displacement measurement on butterflies' wings using the optical noninvasive Digital Holographic Interferometry technique with out of plane sensitivity, using a high power cw laser and a high speed CMOS camera to record the unrepeatable displacement movements on these organic tissues. A series of digital holographic interferograms were recorded and the experimental results for several butterflies during flapping events. The relative unwrapped phase maps micro-displacements over the whole wing surface are shown in a wire-mesh representation. The difference between flying modes is remarkably depicted among them.

  7. State injection, lattice surgery, and dense packing of the deformation-based surface code

    NASA Astrophysics Data System (ADS)

    Nagayama, Shota; Satoh, Takahiko; Van Meter, Rodney

    2017-01-01

    Resource consumption of the conventional surface code is expensive, in part due to the need to separate the defects that create the logical qubit far apart on the physical qubit lattice. We propose that instantiating the deformation-based surface code using superstabilizers will make it possible to detect short error chains connecting the superstabilizers, allowing us to place logical qubits close together. Additionally, we demonstrate the process of conversion from the defect-based surface code, which works as arbitrary state injection, and a lattice-surgery-like controlled not (cnot) gate implementation that requires fewer physical qubits than the braiding cnot gate. Finally, we propose a placement design for the deformation-based surface code and analyze its resource consumption; large-scale quantum computation requires 25/d2+170 d +289 4 physical qubits per logical qubit, where d is the code distance of the standard surface code, whereas the planar code requires 16 d2-16 d +4 physical qubits per logical qubit, for a reduction of about 50%.

  8. Bulk and particle strain analysis in high-temperature deformation experiments

    NASA Astrophysics Data System (ADS)

    Quane, Steven L.; Russell, J. K.

    2006-06-01

    Experimental data alone are not sufficient to describe the rheology of deformed geomaterials. To fully characterize a material's rheological properties, independent verification of deformation mechanisms is required. Here, we use standard image analysis techniques to semi-quantify the physical changes in experimentally deformed cores of soda-lime silica glass beads and rhyolite ash previously described by Quane and Russell [Quane, S.L., Russell, J.K., 2005a. Welding: insights from high-temperature analogue experiments. J. Volcanol. Geotherm. Res. 142, 67-87]. The properties we measure by image analysis include porosity, radial bulging and particle elongation. The image analysis measurements combined with digital output from the experiments allow us to determine the amount of total axial and radial strain accumulated by the bulk sample ( ɛb) and by individual particles ( ɛp). We demonstrate that these metrics of strain are nearly equal to the one-dimensional strain recorded by the deformation apparatus ( ɛm) and sample shortening ( ɛs), confirming that all strain introduced by the deformation apparatus is being transferred into both the bulk sample and individual particles. We also show that ɛb is manifest as two discrete components: axial ( ɛa) and radial ( ɛr) strain. We use these independent components of strain accumulation to show that, despite having nearly identical strain-time and stress-strain deformation paths, glass bead cores and rhyolite ash cores have strikingly different mechanisms of strain accumulation. In the higher porosity rhyolite ash cores, axial strain dominates, implying that, under the conditions present, natural glassy particulate geomaterials deform almost entirely by porosity loss.

  9. Hydrostatic Stress Effects Incorporated Into the Analysis of the High-Strain-Rate Deformation of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.

    2003-01-01

    Procedures for modeling the effect of high strain rate on composite materials are needed for designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. The nonlinearity and strain rate dependence of the composite response is primarily due to the matrix constituent. Therefore, in developing material models to be used in the design of impact-resistant composite engine cases, the deformation of the polymer matrix must be correctly analyzed. However, unlike in metals, the nonlinear response of polymers depends on the hydrostatic stresses, which must be accounted for within an analytical model. An experimental program has been carried out through a university grant with the Ohio State University to obtain tensile and shear deformation data for a representative polymer for strain rates ranging from quasi-static to high rates of several hundred per second. This information has been used at the NASA Glenn Research Center to develop, characterize, and correlate a material model in which the strain rate dependence and nonlinearity (including hydrostatic stress effects) of the polymer are correctly analyzed. To obtain the material data, Glenn s researchers designed and fabricated test specimens of a representative toughened epoxy resin. Quasi-static tests at low strain rates and split Hopkinson bar tests at high strain rates were then conducted at the Ohio State University. The experimental data confirmed the strong effects of strain rate on both the tensile and shear deformation of the polymer. For the analytical model, Glenn researchers modified state variable constitutive equations previously used for the viscoplastic analysis of metals to allow for the analysis of the nonlinear, strain-rate-dependent polymer deformation. Specifically, we accounted for the effects of

  10. High voltage, high resolution, digital-to-analog converter for driving deformable mirrors

    NASA Astrophysics Data System (ADS)

    Kittredge, Jeffrey

    Digital-to-analog converters with a range over 50 volts are required for driving micro-electro mechanical system deformable mirrors used in adaptive optics. An existing tested and deployed DM driver has 1024 channels and resolution of 15mV per Least Significant Bit. DMs used in the search for exoplanets require 3mV per LSB resolution. A technique is presented to employ a secondary high resolution and low voltage DAC which has for it's ground the output of the high voltage DAC. The entire system then has the range of high voltage DAC yet the resolution of the low voltage DAC. A method for providing signal and power to the floating system is given. Rudimentary micro controller firmware and also PC software is presented to achieve complete functionality. The technique uses all off-the-shelf components. Resolution of 1.6mV per LSB, 60V range and 36mW of power per channel is achieved.

  11. Self-localized states for electron transfer in nonlocal continuum deformable media

    NASA Astrophysics Data System (ADS)

    Cisneros-Ake, Luis A.

    2016-08-01

    We consider the problem of electron transport in a deformable continuum medium subjected to an external harmonic substrate potential. We then consider the quasi-stationary state of the full problem to find a Gross-Pitaevskii type equation with a nonlocal external potential, which is solved by variational and numerical means (considered as the exact solution) to find the parameter conditions for the existence of self-localized solutions. The variational approach predicts a threshold on the on-site or nonlocality parameter where localized solutions cease to exist from the Non-Linear Schrödinger soliton limit. A numerical continuation of stationary state solutions in the corresponding discrete system is used to confirm the prediction of the turning value in the on-site term. We finally study the full stationary state and make use of an approximation, proposed by Briedis et al. [17], for the nonlocal term, corresponding to strong nonlocalities, to find analytic expressions for self-localized states in terms of the series solutions of a nonlinear modified Bessel equation.

  12. High-rate deformation of nanocrystalline iron and copper

    NASA Astrophysics Data System (ADS)

    Sinani, A. B.; Shpeizman, V. V.; Vlasov, A. S.; Zil'berbrand, E. L.; Kozachuk, A. I.

    2016-11-01

    Stress-strain curves are recorded during a high-speed impact and slow loading for nanocrystalline and coarse-grained iron and copper. The strain-rate sensitivity is determined as a function of the grain size and the strain. It is shown that the well-known difference between the variations of the strain-rate sensitivity of the yield strength with the grain size in fcc and bcc metals can be extended to other strain dependences: the strain-rate sensitivity of flow stresses in iron decreases with increasing strain, and that in copper increases. This difference also manifests itself in different slopes of the dependence of the strain-rate sensitivity on the grain size when the strain changes.

  13. Deformation Behavior and Dynamic Recrystallization of Micro-Alloyed Mg-Al-Ca Alloys During High Temperature Deformation

    NASA Astrophysics Data System (ADS)

    Su, Jing; Kabir, Abu Syed Humaun; Jung, In-Ho; Yue, Steve

    Two micro-alloyed magnesium alloys, Mg-0.3Al-0.2Ca (AX0302) and Mg-0.1Al-0.5Ca (AX0105), were designed based on the thermodynamics calculation in terms of precipitation temperature. Hot compression tests were conducted at temperatures of 300°C, 350°C and 400°C with strain rates of 0.1s-1, 0.01s-1 and 0.001s-1. Dynamic precipitation of Al2Ca could be found below 400°C in AX0302, while Mg2Ca dynamically formed in AX0105 during deformation at all three temperatures. At high temperature and low strain rate (400°C at 0.01s-1 and 0.001s-1 and 350°C at 0.001s-1), DRX mainly developed at the grain boundaries and formed necklace type microstructure in both alloys. However, at lower temperature and higher strain rate, DRX grains formed at both grain boundaries and twinning boundaries. The combination effect of twinning and dynamic precipitation on dynamic recrystallization was studied by comparing with two alloys.

  14. The transition from discontinuous to continuous recrystallization in some aluminium alloys I - the deformed state

    SciTech Connect

    Jazaeri, H.; Humphreys, F.J

    2004-06-21

    The microstructures developed during deformation to large rolling strains in single and two-phase aluminium alloys with a wide range of grain sizes has been investigated, and the major parameters of the microstructure determined by high resolution electron backscatter diffraction (EBSD). It is found that the behaviour of initially fine-grained (<5 {mu}m) alloys is significantly different from that of the large-grained (>50 {mu}m) alloys. In the finer-grained alloys no significant grain fragmentation occurs, and at larger strains, when the spacing of high angle boundaries approaches the crystallite size, a considerable amount of the high angle boundary is removed by a process of dynamic recovery.

  15. High Rate of Deformed Larvae among Gynogenetic Brown Trout (Salmo trutta m. fario) Doubled Haploids.

    PubMed

    Jagiełło, Krzysztof; Zalewski, Tomasz; Dobosz, Stefan; Michalik, Oliwia; Ocalewicz, Konrad

    2017-01-01

    Mitotic gynogenesis results in the production of fully homozygous individuals in a single generation. Since inbred fish were found to exhibit an increased frequency of body deformations that may affect their survival, the main focus of this research was to evaluate the ratio of individuals with spinal deformities among gynogenetic doubled haploids (DHs) brown trout as compared to nonmanipulated heterozygous individuals. Gynogenetic development was induced by the activation of brown trout eggs by UV-irradiated homologous and heterologous (rainbow trout) spermatozoa. The subsequent exposure of the activated eggs to the high hydrostatic pressure disturbed the first cleavage in gynogenetic zygotes and enabled duplication of the maternal haploid set of chromosomes. The survival rate was significantly higher among gynogenetic brown trout hatched from eggs activated with the homologous UV-irradiated spermatozoa when compared to DHs hatched from eggs activated by the heterologous spermatozoa. More than 35% of the gynogenetic larvae exhibited body deformities, mostly lordosis and scoliosis. The percentage of malformed brown trout from the control group did not exceed 15%. The increased number of deformed larvae among DHs brown trout suggested rather a genetic background of the disease related to the fish spine deformities; however, both genetic and environmental factors were discussed as a cause of such conditions in fish.

  16. Global lifetime measurements of highly deformed and other rotational structures in the A ~ 135 light rare-earth region

    NASA Astrophysics Data System (ADS)

    Laird, Robert William

    While the quadrupole moments of various rotational structures in the A ~ 135 light rare-earth region have been determined by different groups in the past, conclusive comparisons have been limited because of systematic differences in experimental setup and analysis procedures. With this in mind, a global lifetime experiment was performed using the GAMMASPHERE spectrometer coupled with the Washington University MICROBALL charged-particle detector. High-spin states of a variety of A ~ 135 nuclei (Z = 58 - 62) were populated after fusion of a 35Cl beam with a Au backed 105Pd target. The 173 MeV 35Cl beam was provided by the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. Since a variety of nuclei (Pr, Nd, Pm, and Sm) were produced under the same experimental conditions, relative deformation measurements taken from this data set were then meaningful. The Doppler-shift attenuation method was used to extract average quadrupole moments for both the normal deformed and highly-deformed structures in this region. This study, the most comprehensive in any mass region, establishes Z, N, and configuration dependent quadrupole moment trends in the A ~ 135 light rare-earth region. The extracted quadrupole moments were then compared with theoretical calculations obtained using the Hartree-Fock framework.

  17. Columnar deformation of human red blood cell by highly localized fiber optic Bessel beam stretcher

    PubMed Central

    Lee, Sungrae; Joo, Boram; Jeon, Pyo Jin; Im, Seongil; Oh, Kyunghwan

    2015-01-01

    A single human red blood cell was optically stretched along two counter-propagating fiber-optic Bessel-like beams in an integrated lab-on-a-chip structure. The beam enabled highly localized stretching of RBC, and it induced a nonlinear mechanical deformation to finally reach an irreversible columnar shape that has not been reported. We characterized and systematically quantified this optically induced mechanical deformation by the geometrical aspect ratio of stretched RBC and the irreversible stretching time. The proposed RBC mechanism can realize a versatile and compact opto-mechanical platform for optical diagnosis of biological substances in the single cell level. PMID:26601005

  18. Numerical modelling of the evolution of conglomerate deformation up to high simple-shear strain

    NASA Astrophysics Data System (ADS)

    Ran, Hao; Bons, Paul D.; Wang, Genhou; Steinbach, Florian; Finch, Melanie; Ran, Shuming; Liang, Xiao; Zhou, Jie

    2017-04-01

    Deformed conglomerates have been widely used to investigate deformation history and structural analysis, using strain analyses techniques, such as the Rf-Φ and Fry methods on deformed pebbles. Although geologists have focused on the study of deformed conglomerates for several decades, some problems of the process and mechanism of deformation, such as the development of structures in pebbles and matrix, are still not understand well. Numerical modelling provides a method to investigate the process of deformation, as a function of different controlling parameters, up to high strains at conditions that cannot be achieved in the laboratory. We use the 2D numerical modelling platform Elle coupled to the full field crystal visco-plasticity code (VPFFT) to simulate the deformation of conglomerates under simple shear conditions, achieving high finite strains of ≥10. Probably for the first time, we included the effect of an anisotropy, i.e. mica-rich matrix. Our simulations show the deformation of pebbles not only depends on the viscosity contrast between pebbles and matrix but emphasises the importance of interaction between neighbouring pebbles. Under the same finite strain shearing the pebbles of conglomerates with high pebble densities show higher Rf and lower Φ than those of conglomerates with a low density pebbles. Strain localisation can be observed at both the margin of strong pebbles and in the bridging area between the pebbles. At low to medium finite strain, local areas show the opposite (antithetic) shear sense because of the different relative rotation and movement of pebbles or clusters of pebbles. Very hard pebbles retain their original shape and may rotate, depending on the anisotropy of the matrix. σ-clasts are formed by pebbles with moderate viscosity contrast between pebble and a softer matrix. By contrast, δ-clasts are not observed in our simulations with both isotropic and anisotropic matrices, which is consistent with their relative scarcity in

  19. Large-Deformation Displacement Transfer Functions for Shape Predictions of Highly Flexible Slender Aerospace Structures

    NASA Technical Reports Server (NTRS)

    Ko, William L.; Fleischer, Van Tran

    2013-01-01

    Large deformation displacement transfer functions were formulated for deformed shape predictions of highly flexible slender structures like aircraft wings. In the formulation, the embedded beam (depth wise cross section of structure along the surface strain sensing line) was first evenly discretized into multiple small domains, with surface strain sensing stations located at the domain junctures. Thus, the surface strain (bending strains) variation within each domain could be expressed with linear of nonlinear function. Such piecewise approach enabled piecewise integrations of the embedded beam curvature equations [classical (Eulerian), physical (Lagrangian), and shifted curvature equations] to yield closed form slope and deflection equations in recursive forms.

  20. Extrinsic and intrinsic fracture behavior of high pressure torsion deformed nickel

    PubMed Central

    Rathmayr, Georg B.; Pippan, Reinhard

    2012-01-01

    Nickel discs (>99.5 wt.%) were deformed by high pressure torsion (HPT) at different temperatures (−196 °C, 25 °C, 200 °C, and 400 °C) until saturation was reached. The strength and fracture behavior of microdefect-free samples and samples with inclusions were investigated using micro and macro tensile tests, respectively. The fracture behavior is not sensitive to the HPT deformation temperature but differs significantly in the two types of sample. The ultimate tensile strength is not affected by inclusions or grain texture. PMID:23471511

  1. High pressure and temperature deformation experiments on San Carlos olivine and implications for upper mantle anisotropy

    NASA Astrophysics Data System (ADS)

    Shekhar, Sushant; Frost, Daniel J.; Walte, Nicolas; Miyajima, Nobuyoshi; Heidelbach, Florian

    2010-05-01

    Crystallographic preferred orientation developed in olivine due to shearing in the mantle is thought to be the prominent reason behind seismic anisotropy in the upper mantle. Seismic anisotropy in upper mantle can be observed up to a depth of 350 km with a marked drop in the strength of anisotropy seen around 250 km. Studies on natural rock samples from the mantle and deformation experiments performed on olivine have revealed that olivine deforms mainly through dislocation creep with Burgers vectors parallel to the [100] crystallographic axis under low pressure conditions (up to 3 GPa). Under similar pressures, evidence of [001] slip has been reported due to the presence of water. In order to understand the deformation mechanism in olivine at pressures greater than 3 GPa, we have performed experiments using the deformation DIA multi-anvil apparatus. The DIA consist of 6 square faceted anvils that compress a cubic high-pressure assembly. The deformation DIA possesses two vertically acting opposing inner rams, which can be operated independently of the main compressive force to deform the sample assembly. The experimental setup consists of a hot-pressed sample of polycrystalline dry San Carlos olivine 0.2 mm cut from a 1.2 mm diameter core at 45° . This slice is sandwiched between alumina pistons also cut at 45° in simple shear geometry. Experiments have been performed at 3, 5 and 8 GPa at a deformation anvil strain rate of 1.0x10-4 s-1and temperatures between 1200-1400° C. Deformed samples were cut normal to the shear plane and parallel to the shear direction. Then the sample was polished and analyzed using electron back scattered diffraction (EBSD) to identify the crystallographic preferred orientation (CPO). The fabric that developed in olivine deformed at 3 GPa mainly resulted from the [100] slip on the (010) plane. Samples deformed at 5 GPa showed both [100] and [001] slip. On the other hand, samples deformed at 8 GPa and 1200° C, show deformation mainly

  2. Nonlinear deformation of skeletal muscles in a passive state and in isotonic contraction

    NASA Astrophysics Data System (ADS)

    Shil'ko, S. V.; Chernous, D. A.; Pleskachevskii, Yu. M.

    2012-07-01

    A procedure for a two-level modeling of deformation of skeletal muscles is offered. Based on a phenomenological model of an individual muscle fiber, consisting of a viscous, a contractive, and two nonlinearly elastic elements (the first level), various means for describing a skeletal muscle as a whole (the second, macroscopic level) are considered. A method for identification of a muscle model by utilizing experimental elongation diagrams in a passive state and in isotonic contraction is put forward. The results of a biomechanical analysis are compared with known experimental data for the isotonic and isometric activation regimes of tailor's muscle of a frog. It is established that preferable is the description of a muscle that takes into account the different lengths of muscle fibers and their twist.

  3. High Temperature Deformation Mechanisms in a DLD Nickel Superalloy

    PubMed Central

    Davies, Sean; Jeffs, Spencer; Lancaster, Robert; Baxter, Gavin

    2017-01-01

    The realisation of employing Additive Layer Manufacturing (ALM) technologies to produce components in the aerospace industry is significantly increasing. This can be attributed to their ability to offer the near-net shape fabrication of fully dense components with a high potential for geometrical optimisation, all of which contribute to subsequent reductions in material wastage and component weight. However, the influence of this manufacturing route on the properties of aerospace alloys must first be fully understood before being actively applied in-service. Specimens from the nickel superalloy C263 have been manufactured using Powder Bed Direct Laser Deposition (PB-DLD), each with unique post-processing conditions. These variables include two build orientations, vertical and horizontal, and two different heat treatments. The effects of build orientation and post-process heat treatments on the materials’ mechanical properties have been assessed with the Small Punch Tensile (SPT) test technique, a practical test method given the limited availability of PB-DLD consolidated material. SPT testing was also conducted on a cast C263 variant to compare with PB-DLD derivatives. At both room and elevated temperature conditions, differences in mechanical performances arose between each material variant. This was found to be instigated by microstructural variations exposed through microscopic and Energy Dispersive X-ray Spectroscopy (EDS) analysis. SPT results were also compared with available uniaxial tensile data in terms of SPT peak and yield load against uniaxial ultimate tensile and yield strength. PMID:28772817

  4. Deformation behavior of titanate nanotubes subjected to high pressure

    NASA Astrophysics Data System (ADS)

    Ojeda-Galván, H. J.; Rodríguez, A. G.; Santos-López, I. A.; Mendoza-Cruz, R.; Yacamán, M. J.; Handy, B. E.

    2017-01-01

    Nano-sized titania (anatase) and sodium and potassium titanate nanotubes were studied via in situ Raman spectroscopy at hydrostatic pressures up to 6 GPa. Analysis by scanning electron microscopy shows a uniform dispersion of sodium and potassium cations in the nanotubes. The effect of the pressure was observed by significant shifts in the Raman band structure of nano-sized anatase crystals and nanotube titanate. In nano-particulate anatase, the phonon frequencies (143, 395, 517, and 639 cm-1) increase linearly with pressure. In contrast, the upward frequency shifts in the sodium titanate nanotubes (NaTNT) and potassium-modified nanotubes (NaTNT+K) occur in a stepwise fashion. These stepwise changes occur in the nanotube samples between 2 and 4 GPa (ambient pressure phonon bands in NaTNT at 274, 444, 650, and 906 cm-1) and between 4.5 and 5.5 GPa, (phonons 273 cm-1 and 436 cm-1 in NaTNT+K at an ambient pressure). Post-pressure high-resolution transmission electron microscopy analysis shows evidence of nanotube distortions and a 5% contraction in the interlaminar spacing of both NaTNT and NaTNT+K.

  5. High Temperature Deformation Mechanisms in a DLD Nickel Superalloy.

    PubMed

    Davies, Sean; Jeffs, Spencer; Lancaster, Robert; Baxter, Gavin

    2017-04-26

    The realisation of employing Additive Layer Manufacturing (ALM) technologies to produce components in the aerospace industry is significantly increasing. This can be attributed to their ability to offer the near-net shape fabrication of fully dense components with a high potential for geometrical optimisation, all of which contribute to subsequent reductions in material wastage and component weight. However, the influence of this manufacturing route on the properties of aerospace alloys must first be fully understood before being actively applied in-service. Specimens from the nickel superalloy C263 have been manufactured using Powder Bed Direct Laser Deposition (PB-DLD), each with unique post-processing conditions. These variables include two build orientations, vertical and horizontal, and two different heat treatments. The effects of build orientation and post-process heat treatments on the materials' mechanical properties have been assessed with the Small Punch Tensile (SPT) test technique, a practical test method given the limited availability of PB-DLD consolidated material. SPT testing was also conducted on a cast C263 variant to compare with PB-DLD derivatives. At both room and elevated temperature conditions, differences in mechanical performances arose between each material variant. This was found to be instigated by microstructural variations exposed through microscopic and Energy Dispersive X-ray Spectroscopy (EDS) analysis. SPT results were also compared with available uniaxial tensile data in terms of SPT peak and yield load against uniaxial ultimate tensile and yield strength.

  6. An Immersed-Boundary method for deformable bodies at high Reynolds numbers

    NASA Astrophysics Data System (ADS)

    de Marinis, Dario; Krishnan, Sreenath; de Tullio, Marco Donato; Napolitano, Michele; Pascazio, Giuseppe; Iaccarino, Gianluca

    2015-11-01

    With the aim of accurately simulate the flow-field through gas turbine blades a numerical approach is presented, that couples a massively parallel, finite volume Unsteady Reynolds Averaged Navier-Stokes Equations solver with an efficient structural solver describing the dynamics of deformable bodies, using an iterative coupled approach. The numerical strategy is based on a suitable version of the immersed boundary (IB) technique, which is able to handle rigid and deformable complex geometries in turbulent flows. The structures are discretized by a surface mesh of three-node triangular elements and modeled by means of a finite element method. The solution of the fluid-structure-interaction (FSI) problem produces detailed information of the flow patterns through realistic geometries subject to small deformations at high Reynolds and Mach numbers. Via Orabona 4 - 70125 - Bari, Italy.

  7. Temperature effects on deformation and serration behavior of high-entropy alloys (HEAs)

    DOE PAGES

    Antonaglia, J.; Xie, X.; Tang, Z.; ...

    2014-09-16

    Many materials are known to deform under shear in an intermittent way with slip avalanches detected as acoustic emission and serrations in the stress–strain curves. Similar serrations have recently been observed in a new class of materials, called high-entropy alloys (HEAs). Here, we discuss the serration behaviors of several HEAs from cryogenic to elevated temperatures. The experimental results of slow compression and tension tests are compared with the predictions of a slip-avalanche model for the deformation of a broad range of solids. The results shed light on the deformation processes in HEAs. Temperature effects on the distributions of stress dropsmore » and the decrease of the cutoff (i.e., of the largest observed slip size) for increasing temperature qualitatively agree with the model predictions. As a result, the model is used to quantify the serration characteristics of HEAs, and pertinent implications are discussed.« less

  8. Temperature effects on deformation and serration behavior of high-entropy alloys (HEAs)

    SciTech Connect

    Antonaglia, J.; Xie, X.; Tang, Z.; Tsai, C. -W.; Qiao, J. W.; Zhang, Y.; Laktionova, M. O.; Tabachnikova, E. D.; Yeh, J. W.; Senkov, O. N.; Gao, M. C.; Uhl, J. T.; Liaw, P. K.; Dahmen, K. A.

    2014-09-16

    Many materials are known to deform under shear in an intermittent way with slip avalanches detected as acoustic emission and serrations in the stress–strain curves. Similar serrations have recently been observed in a new class of materials, called high-entropy alloys (HEAs). Here, we discuss the serration behaviors of several HEAs from cryogenic to elevated temperatures. The experimental results of slow compression and tension tests are compared with the predictions of a slip-avalanche model for the deformation of a broad range of solids. The results shed light on the deformation processes in HEAs. Temperature effects on the distributions of stress drops and the decrease of the cutoff (i.e., of the largest observed slip size) for increasing temperature qualitatively agree with the model predictions. As a result, the model is used to quantify the serration characteristics of HEAs, and pertinent implications are discussed.

  9. The effect of aspect ratio on the compressive high rate deformation of three metallic alloys

    NASA Astrophysics Data System (ADS)

    Walley, S. M.; Radford, D. D.; Chapman, D. J.

    2006-08-01

    Metallic cylinders of rolled homogeneous armour (RHA) steel, Ti6Al4V, and FNC tungsten alloy of four different length l to diameter d ratios (dimensions in mm): 8/4, 4/8, 10/8, 8/10) were deformed at high rates of deformation using a direct impact Hopkinson pressure bar. Highspeed photographic sequences of the deformation were taken using a Hadland Imacon 790 imageconverter camera working at either 1 or 2 x 104 frames/s. It was found that titanium alloy cylinders of all four aspect ratios shear-banded and fractured, but that cylinders made from RHA steel and FNC tungsten behaved in a ductile manner when l/d < 1 but in a brittle manner when l/d > 1. We conclude that adiabatic shear banding is not just an inherent material property but that in some materials size effects/geometry can trigger this phenomenon.

  10. Role of deformation twins in static recrystallization kinetics of high-purity alpha titanium

    NASA Astrophysics Data System (ADS)

    Won, Jong Woo; Lee, Taekyung; Hong, Seong-Gu; Lee, Yongmoon; Lee, Jeong Hun; Lee, Chong Soo

    2016-11-01

    The importance of deformation twins in static recrystallization kinetics of high-purity alpha titanium was investigated by carrying out thermal annealing tests of deformed materials in combination with electron-backscatterdiffraction- based microstructural analysis. Prior to thermal annealing, the material was compressed to a true strain of 0.22 along three directions to introduce different twinning characteristics. Our results showed that deformation twins substantially promoted the static recrystallization process by deepening the microstructural inhomogeneity induced by the formation of twin boundaries and twinning-induced crystallographic lattice reorientation. Twin morphology was also observed to be important because it influenced the extent of microstructural inhomogeneity. Intersecting twin morphology, caused by the activation of multiple twin variants, was more effective than parallel twin morphology, caused by the activation of a single twin variant (or a twin variant pair), because it gave rise to more twin boundaries, more twin boundary junctions (intersections, triple junctions, etc.), and greater in-grain crystallographic orientation spread.

  11. High Strain Rate Deformation Modeling of a Polymer Matrix Composite. Part 2; Composite Micromechanical Model

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Stouffer, Donald C.

    1998-01-01

    Recently applications have exposed polymer matrix composite materials to very high strain rate loading conditions, requiring an ability to understand and predict the material behavior under these extreme conditions. In this second paper of a two part report, a three-dimensional composite micromechanical model is described which allows for the analysis of the rate dependent, nonlinear deformation response of a polymer matrix composite. Strain rate dependent inelastic constitutive equations utilized to model the deformation response of a polymer are implemented within the micromechanics method. The deformation response of two representative laminated carbon fiber reinforced composite materials with varying fiber orientation has been predicted using the described technique. The predicted results compare favorably to both experimental values and the response predicted by the Generalized Method of Cells, a well-established micromechanics analysis method.

  12. High-pressure creep of serpentine, interseismic deformation, and initiation of subduction.

    PubMed

    Hilairet, Nadege; Reynard, Bruno; Wang, Yanbin; Daniel, Isabelle; Merkel, Sebastien; Nishiyama, Norimasa; Petitgirard, Sylvain

    2007-12-21

    The supposed low viscosity of serpentine may strongly influence subduction-zone dynamics at all time scales, but until now its role could not be quantified because measurements relevant to intermediate-depth settings were lacking. Deformation experiments on the serpentine antigorite at high pressures and temperatures (1 to 4 gigapascals, 200 degrees to 500 degrees C) showed that the viscosity of serpentine is much lower than that of the major mantle-forming minerals. Regardless of the temperature, low-viscosity serpentinized mantle at the slab surface can localize deformation, impede stress buildup, and limit the downdip propagation of large earthquakes at subduction zones. Antigorite enables viscous relaxation with characteristic times comparable to those of long-term postseismic deformations after large earthquakes and slow earthquakes. Antigorite viscosity is sufficiently low to make serpentinized faults in the oceanic lithosphere a site for subduction initiation.

  13. High resolution transmission electron microscope observation of zero-strain deformation twinning mechanisms in Ag.

    PubMed

    Liu, L; Wang, J; Gong, S K; Mao, S X

    2011-04-29

    We have observed a new deformation-twinning mechanism using the high resolution transmission electron microscope in polycrystalline Ag films, zero-strain twinning via nucleation, and the migration of a Σ3{112} incoherent twin boundary (ITB). This twinning mechanism produces a near zero macroscopic strain because the net Burgers vectors either equal zero or are equivalent to a Shockley partial dislocation. This observation provides new insight into the understanding of deformation twinning and confirms a previous hypothesis: detwinning could be accomplished via the nucleation and migration of Σ3{112} ITBs. The zero-strain twinning mechanism may be unique to low staking fault energy metals with implications for their deformation behavior.

  14. Hardening of Steel with High-Speed Deformation in Wide Temperature Range,

    DTIC Science & Technology

    1980-02-28

    are higher than after shcck wave deformation [2]. It saculd also be noted that the cbserved effects way have the same cider as in the hardening...quenchirg] cf steel and a somewhat hi~ar cider than in static defcrmaticn bith high degrees of reducticc. Finally we must mention the tact that the scurce

  15. Modeling and Characterization of PMMA for High Strain-Rate and Finite Deformations (Postprint)

    DTIC Science & Technology

    2010-05-01

    Appl. Phys. 96, 7696 (2004). 5. Hudson, L.C. Ill, and Bernecker, R.R., Propellants, Explosives, Pyrotechnics 20, 330 (1995). 6. Sutherland, G...Structures 43, 1331 (2006). MuUiken, A.D., Mechanics of amorphous polymers and polymer nanocomposites during high rate deformation, Ph.D

  16. Microstructure and Corrosion Behavior of Hot-Deformed and Cold-Strained High-Mn Steels

    NASA Astrophysics Data System (ADS)

    Grajcar, A.; Kciuk, M.; Topolska, S.; Płachcińska, A.

    2016-06-01

    The electrochemical corrosion properties of 26Mn-3Si-3Al and 27Mn-4Si-2Al austenitic steels in two different states were studied in 0.1 M H2SO4 and 3.5% NaCl using potentiodynamic polarization tests. The effect of cold deformation on the microstructure and corrosion behavior of steels was analyzed. In acid solution, both steels exhibited lower corrosion resistance than in chloride solution independently on the steel state (hot-rolled, cold-worked). Cold deformation decreases the corrosion resistance, though this effect is smaller than the effect of chemical composition related to the combined Al + Si addition. All steels showed the evidence of pitting corrosion. The intensive dissolution of Fe and Mn takes place in the acid medium.

  17. Highly deformable and highly fluid vesicles as potential drug delivery systems: theoretical and practical considerations

    PubMed Central

    Romero, Eder Lilia; Morilla, Maria Jose

    2013-01-01

    Vesicles that are specifically designed to overcome the stratum corneum barrier in intact skin provide an efficient transdermal (systemic or local) drug delivery system. They can be classified into two main groups according to the mechanisms underlying their skin interaction. The first group comprises those possessing highly deformable bilayers, achieved by incorporating edge activators to the bilayers or by mixing with certain hydrophilic solutes. The vesicles of this group act as drug carriers that penetrate across hydrophilic pathways of the intact skin. The second group comprises those possessing highly fluid bilayers, owing to the presence of permeation enhancers. The vesicles of this group can act as carriers of drugs that permeate the skin after the barrier of the stratum corneum is altered because of synergistic action with the permeation enhancers contained in the vesicle structure. We have included a detailed overview of the different mechanisms of skin interaction and discussed the most promising preclinical applications of the last five years of Transfersomes® (IDEA AG, Munich, Germany), ethosomes, and invasomes as carriers of antitumoral and anti-inflammatory drugs applied by the topical route. PMID:23986634

  18. Transmission electron microscopic studies of deformed high-palladium dental alloys.

    PubMed

    Guo, W H; Brantley, W A; Clark, W A T; Xiao, J Z; Papazoglou, E

    2003-06-01

    Objective. The purpose of this study was to employ transmission electron microscopy (TEM) to investigate the microstructures of Pd-Cu-Ga and Pd-Ga dental alloys that had been permanently deformed, in order to obtain information about the deformation behavior of individual phases and changes in microstructure brought about by that deformation.Methods. Heavily deformed regions taken from fractured tensile test bars of the two alloys in the as-cast condition were prepared for TEM analysis, using mechanical grinding and polishing, ion milling, and plasma cleaning. The specimens were examined in the TEM using bright-field and dark-field diffraction contrast imaging. Selected-area and convergent-beam electron diffraction patterns were employed to analyze the structures of the phases, and standardless energy-dispersive X-ray spectrometry was used to determine their mean compositions.Results. For both alloys, tweed structures underwent permanent deformation by twinning, whereas dislocation movement occurred in the face-centered cubic (fcc) palladium solid solution matrix. A body-centered cubic (bcc) phase, previously unreported in our TEM studies and containing a high density of dislocations, was identified in the Pd-Cu-Ga alloy, while fine-scale, stress-induced precipitates were found in some regions of the fcc matrix in the Pd-Ga alloy.Significance. The present results have provided novel information about the mechanical deformation behavior of high-palladium alloys. The stress-induced precipitation in the Pd-Ga dental alloy studied may be a critical component of strengthening mechanisms.

  19. Effect of the molecular weight on deformation states of the polystyrene film by AFM single scanning.

    PubMed

    Sun, Yang; Yan, Yongda; Liang, Yingchun; Hu, Zhenjiang; Zhao, Xuesen; Sun, Tao; Dong, Shen

    2013-01-01

    Nanobundles patterns can be formed on the surface of most thermoplastic polymers when the atomic force microscope (AFM)-based nanomechanical machining method is employed to scratch their surfaces. Such patterns are reviewed as three-dimensional sine-wave structures. In the present study, the single-line scratch test is used firstly to study different removal states of the polystyrene (PS) polymer with different molecular weights (MWs). Effects of the scratching direction and the scratching velocity on deformation of the PS film and the state of the removed materials are also investigated. Single-wear box test is then employed to study the possibility of forming bundle structures on PS films with different MWs. The experimental results show that the state between the tip and the sample plays a key role in the nano machining process. If the contact radius between the AFM tip and the polymer surface is larger than the chain end-to-end distance, it is designated as the "cutting" state that means the area of both side ridges is less than the area of the groove and materials are removed. If the contact radius is less than the chain end-to-end distance, it is designated as the "plowing" state that means the area of both side ridges is larger than the area of the groove and no materials are removed at all. For the perfect bundles formation on the PS film, the plowing state is ideal condition for the larger MW polymers because of the chains' entanglement. © Wiley Periodicals, Inc.

  20. High-speed nano-bearings constructed from double-walled carbon nanotubes: Effect of flexile deformation

    NASA Astrophysics Data System (ADS)

    Zhu, Chunzhang; Zhao, Yang

    2013-11-01

    Double-walled carbon nanotubes (DWCNTs) have been proposed to be the leading candidates for high-speed nanobearings owing to superlubric characteristics between adjacent nanotubes. Performance of the DWCNT bearings is closely related to intertube friction, which is influenced by many factors, and in this work, we focus on the issue of flexibility of the nanotubes. Using molecular dynamics simulation, it has been found that considerable deformation of the nanotubes can emerge in the (5, 5)/(18, 0) DWCNT bearing with a length of ˜80 Å if the angular speed of the shaft reaches 1.3 rev/ps. Such flexile deformation results in two distinct states with differing frictional characteristics. One of the two states, the slippery rotation, represents an interim period characterized by in-phase distortions of the inner and outer tubes, while the other state, the resistant rotation, is a steady state with the inner-tube curving lags behind that of the outer tube. Such a lag leads to a considerable increase of circular deflection of the outer tube and a sharp decrease of the minimal distance between tubes, therefore preventing the inner tube from slippery rotation.

  1. Some contributions to the high strain rate deformation of solids and the thermally activated deformation of wood

    NASA Astrophysics Data System (ADS)

    Ferguson, W. George

    2009-08-01

    The behaviour of metals as a function of rate of loading, strain rate, and temperature is discussed in terms of previous work by the author. Strain rates range from 10-3 s-1, obtained in a standard tensile testing machine, to 102 s-1 obtained in a hydraulic piston driven machine and up to 104 s-1, very high strain rates with a Kolsky split Hopkinson bar using shear type loading. At rates less 103 s-1 the strength is a function of strain rate and temperature, is thermally activated and governed by the stress-assisted thermal activation of dislocations across short-range barriers in the crystal. At very high strain rates however the behaviour is controlled by interaction of dislocations with either phonons or electrons, giving a strength proportional to strain rate. The compressive strength of small clear samples of wood, Pinus radiata and Kahikatea, determined over the strain rate range 10-3 s-1 to 103 s-1 as a function of strain rate, temperature and moisture content shows the behaviour to again be thermally activated with the strength a function of stain rate, temperature and moisture content. A rate theory of deformation is developed where the yield behaviour of wood is assumed to result from the stress-assisted thermally activated motion of elementary fibrils over short-range barriers. The moisture is assumed to affect the bond energy between elementary fibrils and the barrier energy is taken to be a linear decreasing function of increasing moisture content and the moisture to act like a plasticiser in separating the elementary fibrils. The theory more than adequately explains the observed behaviour.

  2. Multiscale deformations lead to high toughness and circularly polarized emission in helical nacre-like fibres

    PubMed Central

    Zhang, Jia; Feng, Wenchun; Zhang, Huangxi; Wang, Zhenlong; Calcaterra, Heather A.; Yeom, Bongjun; Hu, Ping An; Kotov, Nicholas A.

    2016-01-01

    Nacre-like composites have been investigated typically in the form of coatings or free-standing sheets. They demonstrated remarkable mechanical properties and are used as ultrastrong materials but macroscale fibres with nacre-like organization can improve mechanical properties even further. The fiber form or nacre can, simplify manufacturing and offer new functional properties unknown yet for other forms of biomimetic materials. Here we demonstrate that nacre-like fibres can be produced by shear-induced self-assembly of nanoplatelets. The synergy between two structural motifs—nanoscale brick-and-mortar stacking of platelets and microscale twisting of the fibres—gives rise to high stretchability (>400%) and gravimetric toughness (640 J g−1). These unique mechanical properties originate from the multiscale deformation regime involving solid-state self-organization processes that lead to efficient energy dissipation. Incorporating luminescent CdTe nanowires into these fibres imparts the new property of mechanically tunable circularly polarized luminescence. The nacre-like fibres open a novel technological space for optomechanics of biomimetic composites, while their continuous spinning methodology makes scalable production realistic. PMID:26907888

  3. Multiscale deformations lead to high toughness and circularly polarized emission in helical nacre-like fibres

    NASA Astrophysics Data System (ADS)

    Zhang, Jia; Feng, Wenchun; Zhang, Huangxi; Wang, Zhenlong; Calcaterra, Heather A.; Yeom, Bongjun; Hu, Ping An; Kotov, Nicholas A.

    2016-02-01

    Nacre-like composites have been investigated typically in the form of coatings or free-standing sheets. They demonstrated remarkable mechanical properties and are used as ultrastrong materials but macroscale fibres with nacre-like organization can improve mechanical properties even further. The fiber form or nacre can, simplify manufacturing and offer new functional properties unknown yet for other forms of biomimetic materials. Here we demonstrate that nacre-like fibres can be produced by shear-induced self-assembly of nanoplatelets. The synergy between two structural motifs--nanoscale brick-and-mortar stacking of platelets and microscale twisting of the fibres--gives rise to high stretchability (>400%) and gravimetric toughness (640 J g-1). These unique mechanical properties originate from the multiscale deformation regime involving solid-state self-organization processes that lead to efficient energy dissipation. Incorporating luminescent CdTe nanowires into these fibres imparts the new property of mechanically tunable circularly polarized luminescence. The nacre-like fibres open a novel technological space for optomechanics of biomimetic composites, while their continuous spinning methodology makes scalable production realistic.

  4. In-situ Phase Transformation and Deformation of Iron at High Pressure andTemperature

    SciTech Connect

    Miyagi, Lowell; Kunz, Martin; Knight, Jason; Nasiatka, James; Voltolini, Marco; Wenk, Hans-Rudolf

    2008-07-01

    With a membrane based mechanism to allow for pressure change of a sample in aradial diffraction diamond anvil cell (rDAC) and simultaneous infra-red laser heating, itis now possible to investigate texture changes during deformation and phasetransformations over a wide range of temperature-pressure conditions. The device isused to study bcc (alpha), fcc (gamma) and hcp (epislon) iron. In bcc iron, room temperature compression generates a texture characterized by (100) and (111) poles parallel to the compression direction. During the deformation induced phase transformation to hcp iron, a subset of orientations are favored to transform to the hcp structure first and generate a texture of (01-10) at high angles to the compression direction. Upon further deformation, the remaining grains transform, resulting in a texture that obeys the Burgers relationship of (110)bcc // (0001)hcp. This is in contrast to high temperature results that indicate that texture is developed through dominant pyramidal {2-1-12}<2-1-13> and basal (0001)-{2-1-10} slip based on polycrystal plasticity modeling. We also observe that the high temperature fcc phase develops a 110 texture typical for fcc metals deformed in compression.

  5. High-temperature deformation behavior and processing map of 7050 aluminum alloy re]20101008

    NASA Astrophysics Data System (ADS)

    Jin, Jun-song; Wang, Xin-yun; Hu, H. E.; Xia, Ju-chen

    2012-02-01

    The high-temperature deformation behavior and processing map of 7050 aluminum alloy were investigated by tensile tests conducted at various temperatures (340, 380, 420, and 460 °C) with various strain rates of 10-4, 10-3, 10-2, and 0.1 s-1. The results show that the instability region with a peak power dissipation efficiency of 100 % occurs at the low deformation temperature region of 340 °C to 380 °C and high strain rates (>10-3 s-1). The 7050 aluminum alloy exhibited a continuous dynamic recrystallization domain with power dissipation efficiency of 35% to 60 % in the deformation temperature range of 410 °C to 460 °C and the strain rate range of 10-4-10-3 s-1. The domain with a power dissipation efficiency of 35 % to 50 % occurring at high deformation temperatures and strain rates was interpreted to represent dynamic recovery. Dynamic recovery and continuous dynamic recrystallization provide chosen domains for excellent hot workability.

  6. Radon and thoron emission from high and low porosity rocks under increasing deformation: An experimental study

    NASA Astrophysics Data System (ADS)

    Vinciguerra, S.; Mollo, S.; Tuccimei, P.; Heap, M. J.; Soligo, M.; Castelluccio, M.; Scarlato, P.; Dingwell, D. B.

    2010-12-01

    Cracking of a medium, observed before earthquake ruptures and/or volcanic eruptions, can produce anomalous increases in the rate of radon emission, as new exhaling surfaces enhance its mobility towards the surface. However, in several cases radon emission rate decreases or does not change significantly before seismic activity and hence the interpretation of such anomalies remains speculative. Quantitative assessment of the rate of radon emission in different rock types with increasing deformation is therefore required to address this problem. Here we present a new experimental dataset where measurements of radon (222Rn) and thoron (220Rn) emissions were carried out on lithophysae-rich tuff (initial porosity = 47.01 %) and crystalline lava flow samples (initial porosity = 3.6 %) incrementally loaded uniaxially with the aim of analysing the relationships between incremental damage and the rate of radon emission. Our results show that deformation in the high-porosity tuff resulted in a decrease in the rate of radon emission; and can be explained by the fact that compactive pore collapse is the dominant deformation mechanism. On the other hand, the low porosity lava flow only showed a change in radon emission rate with increasing deformation upon macroscopic failure. This indicates that microcrack damage, as evidenced by the output of acoustic emissions during deformation, did not improve exhalation surfaces and pathways sufficiently to result in an increase in radon emission rate. However, when microcracks coalesce to form a discrete fault plane, new exhaling surfaces are formed and radon emission rates increase. It is now clear that the initial physical properties (e.g. porosity) of the rock appear crucial for understanding of radon emission anomalies. The interplay of the contrasting styles of deformation (compaction and fracturing) controls the formation/reduction of exhaling surfaces and thus the rate radon emission. These new experimental data can therefore help

  7. High-pressure and high temperature deformation studies of polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Yu, Xiaohui

    2011-03-01

    With Vicker's hardness 120 GPa, shear modulus 535 GPa, diamond is the hardest material known to mankind. However, because diamond is difficult to deform, little is known with regard to its constitutive properties such as yield strength. In this work, we present results obtained at NSLS using deformation-DIA on polycrystalline diamond at different P-T conditions. As expected, even at total strains up to 20%, we did not observe the yield point of diamond at room temperature and a confining pressure of 4 GPa. However, for deformation at 1000 and 1200& circ; C, we observed an plastic flow of diamond at total strains of 10% and 5%, respectively, indicating that diamond weakens rapidly when temperature is over 1000& circ; C. We further derived the micro stress of diamond from peak width analysis, and found that the micro and macro stresses show similar variations with total strain at both room temperature and 1000& circ; C. However, at 1200& circ; C, the micro stress remains constant in entire deformation, indicating that stress is uniformly distributed within diamond particles at 1200& circ; C. We also carried out SEM studies on the recovered samples to investigate the miscrostructures, and find that the grain size of diamond decreases substantially during the deformation, from the initial microns to sub-microns for the room temperature deformation, however, almost doesn't change for the 1200& circ; C.

  8. Deformation of contact surfaces in a vacuum interrupter after high-current interruptions

    NASA Astrophysics Data System (ADS)

    Wang, Haoran; Wang, Zhenxing; Zhou, Zhipeng; Jiang, Yanjun; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan

    2016-08-01

    In a high-current interruption, the contact surface in a vacuum interrupter might be severely damaged by constricted vacuum arcs causing a molten area on it. As a result, a protrusion will be initiated by a transient recovery voltage after current zero, enhancing the local electric field and making breakdowns occur easier. The objective of this paper is to simulate the deformation process on the molten area under a high electric field by adopting the finite element method. A time-dependent Electrohydrodynamic model was established, and the liquid-gas interface was tracked by the level-set method. From the results, the liquid metal can be deformed to a Taylor cone if the applied electric field is above a critical value. This value is correlated to the initial geometry of the liquid metal, which increases as the size of the liquid metal decreases. Moreover, the buildup time of a Taylor cone obeys the power law t = k × E-3, where E is the initial electric field and k is a coefficient related to the material property, indicating a temporal self-similar characteristic. In addition, the influence of temperature has little impact on the deformation but has great impact on electron emission. Finally, the possible reason to initiate a delayed breakdown is associated with the deformation. The breakdown does not occur immediately when the voltage is just applied upon the gap but is postponed to several milliseconds later when the tip is formed on the liquid metal.

  9. Sustained High Basal Motion of the Greenland Ice Sheet Revealed by Borehole Deformation

    NASA Technical Reports Server (NTRS)

    Ryser, Claudia; Luthi, Martin P.; Andrews, Lauren C.; Hoffman, Matthew, J.; Catania, Ginny A.; Hawley, Robert L.; Neumann, Thomas A.; Kristensen, Steen S.

    2014-01-01

    Ice deformation and basal motion characterize the dynamical behavior of the Greenland ice sheet (GrIS). We evaluate the contribution of basal motion from ice deformation measurements in boreholes drilled to the bed at two sites in the western marginal zone of the GrIS. We find a sustained high amount of basal motion contribution to surface velocity of 44-73 percent in winter, and up to 90 percent in summer. Measured ice deformation rates show an unexpected variation with depth that can be explained with the help of an ice-flow model as a consequence of stress transfer from slippery to sticky areas. This effect necessitates the use of high-order ice-flow models, not only in regions of fast-flowing ice streams but in all temperate-based areas of the GrIS. The agreement between modeled and measured deformation rates confirms that the recommended values of the temperature-dependent flow rate factor A are a good choice for ice-sheet models.

  10. Deformation and Spallation of a Magnesium Alloy Under High Strain Rate Loading

    SciTech Connect

    Wang, M.; Lu, L.; Li, C.; Xiao, X.H.; Zhou, X.M.; Zhu, J.; Luo, S. N.

    2016-04-20

    We investigate deformation and damage of a magnesium alloy, AZ91, under high strain rate (similar to 10(5) s(-1)) loading via planar impact. The soft-recovered specimens are examined with electron back-scatter diffraction (EBSD). EBSD analysis reveals three types of twinning: {1012} extension, {10 (1) over bar1} contraction, and {10 (1) over bar1}-{10 (1) over bar2) double twinning, and their number density increases with increasing impact velocity. The extension twins dominate contraction and double twins in size and number. Dislocation densities of the recovered specimens are evaluated with x-ray diffraction, and increase with increasing impact velocity. X-ray tomography is used to resolve three-dimensional microstructure of shock-recovered samples. The EBSD and tomography results demonstrate that the second phase, Mg17Al12, plays an important role in both deformation twinning and tensile cracking. Deformation twinning appears to be a common mechanism in deformation of magnesium alloys at low, medium and high strain rates, in addition to dislocation motion. (C) 2016 Elsevier B.V. All rights reserved.

  11. Friction role in deformation behaviors of high-strength TA18 tubes in numerical control bending

    NASA Astrophysics Data System (ADS)

    Fang, Jun; Liang, Chuang; Lu, Shiqiang; Wang, Kelu; Zheng, Deliang

    2017-09-01

    In order to reveal the friction role in deformation behaviors of high-strength TA18 tubes in numerical control (NC) bending, a three dimensional (3D) elastic-plastic finite element (FE) model of high-strength TA18 tubes for whole process in NC bending was established based on ABAQUS code, and its reliability was validated by the experimental results in literature. Then, the bending deformation behaviors under different friction coefficients between tube and various dies were studied with respect to multiple defects such as wall thinning, wall thickening and cross section deformation. The results show that the wall thinning ratio and cross section deformation ratio increase with the increase of the friction coefficient between mandrel and tube f m or decrease of the friction coefficient between pressure die and tube f p, while the friction coefficient between bending die and tube f b has no obvious effect on these. The wall thickening ratio decreases with the increase of f b, f m or decrease of f p.

  12. Deformation of contact surfaces in a vacuum interrupter after high-current interruptions

    SciTech Connect

    Wang, Haoran; Wang, Zhenxing Zhou, Zhipeng; Jiang, Yanjun; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan

    2016-08-07

    In a high-current interruption, the contact surface in a vacuum interrupter might be severely damaged by constricted vacuum arcs causing a molten area on it. As a result, a protrusion will be initiated by a transient recovery voltage after current zero, enhancing the local electric field and making breakdowns occur easier. The objective of this paper is to simulate the deformation process on the molten area under a high electric field by adopting the finite element method. A time-dependent Electrohydrodynamic model was established, and the liquid-gas interface was tracked by the level-set method. From the results, the liquid metal can be deformed to a Taylor cone if the applied electric field is above a critical value. This value is correlated to the initial geometry of the liquid metal, which increases as the size of the liquid metal decreases. Moreover, the buildup time of a Taylor cone obeys the power law t = k × E{sup −3}, where E is the initial electric field and k is a coefficient related to the material property, indicating a temporal self-similar characteristic. In addition, the influence of temperature has little impact on the deformation but has great impact on electron emission. Finally, the possible reason to initiate a delayed breakdown is associated with the deformation. The breakdown does not occur immediately when the voltage is just applied upon the gap but is postponed to several milliseconds later when the tip is formed on the liquid metal.

  13. Interfacial diffusion in high-temperature deformation of composites: A discrete dislocation plasticity investigation

    NASA Astrophysics Data System (ADS)

    Shishvan, Siamak S.; Pollock, Tresa M.; McMeeking, Robert M.; Deshpande, Vikram S.

    2017-01-01

    We present a discrete dislocation plasticity (DDP) framework to analyse the high temperature deformation of multi-phase materials (composites) comprising a matrix and inclusions. Deformation of the phases is by climb-assisted glide of the dislocations while the particles can also deform due to stress-driven interfacial diffusion. The general framework is used to analyse the uniaxial tensile deformation of a composite comprising elastic particles with dislocation plasticity only present in the matrix phase. When dislocation motion is restricted to only glide within the matrix a strong size effect of the composite strength is predicted with the strength increasing with decreasing unit cell size due to dislocations forming pile-ups against the matrix/particle interface. Interfacial diffusion decreases the composite strength as it enhances the elongation of the elastic particles along the loading direction. When dislocation motion occurs by climb-assisted glide within the matrix the size effect of the strength is reduced as dislocations no longer arrange high energy pile-up structures but rather form lower energy dislocation cell networks. While interfacial diffusion again reduces the composite strength, in contrast to continuum plasticity predictions, the elongation of the particles is almost independent of the interfacial diffusion constant. Rather, in DDP the reduction in composite strength due to interfacial diffusion is a result of changes in the dislocation structures within the matrix and the associated enhanced dislocation climb rates in the matrix.

  14. Force balance and deformation characteristics of anisotropic Arctic sea ice (a high resolution study)

    NASA Astrophysics Data System (ADS)

    Feltham, D. L.; Heorton, H. D.; Tsamados, M.

    2016-12-01

    The spatial distribution of Arctic sea ice arises from its deformation, driven by external momentum forcing, thermodynamic growth and melt. The deformation of Arctic sea ice is observed to have structural alignment on a broad range of length scales. By considering the alignment of diamond-shaped sea ice floes, an anisotropic rheology (known as the Elastic Anisotropic Plastic, EAP, rheology) has been developed for use in a climate sea ice model. Here we present investigations into the role of anisotropy in determining the internal ice stress gradient and the complete force balance of Arctic sea ice using a state-of-the-art climate sea ice model. Our investigations are focused on the link between external imposed dynamical forcing, predominantly the wind stress, and the emergent properties of sea ice, including its drift speed and thickness distribution. We analyse the characteristics of deformation events for different sea ice states and anisotropic alignment over different regions of the Arctic Ocean. We present the full seasonal stress balance and sea ice state over the Arctic ocean. We have performed 10 km basin-scale simulations over a 30-year time scale, and 2 km and 500 m resolution simulations in an idealised configuration. The anisotropic EAP sea ice rheology gives higher shear stresses than the more customary isotropic EVP rheology, and these reduce ice drift speed and mechanical thickening, particularly important in the Archipelago. In the central Arctic the circulation of sea ice is reduced allowing it to grow thicker thermodynamically. The emergent stress-strain rate correlations from the EAP model suggest that it is possible to characterise the internal ice stresses of Arctic sea ice from observable basin-wide deformation and drift patterns.

  15. Octupole deformation in the ground states of even-even Z ˜96 , N ˜196 actinides and superheavy nuclei

    NASA Astrophysics Data System (ADS)

    Agbemava, S. E.; Afanasjev, A. V.

    2017-08-01

    A systematic search for axial octupole deformation in the actinides and superheavy nuclei with proton numbers Z =88 -126 and neutron numbers from the two-proton drip line up to N =210 was performed in covariant density functional theory (DFT) using four state-of-the-art covariant energy density functionals representing different model classes. The nuclei in the Z ˜96 , N ˜196 region of octupole deformation were investigated in detail and the systematic uncertainties in the description of their observables were quantified. A similar region of octupole deformation exists also in Skyrme DFT and microscopic+macroscopic approaches but it is centered at somewhat different particle numbers. Theoretical uncertainties in the predictions of the regions of octupole deformation increase on going to superheavy nuclei with Z ˜120 , N ˜190 . There are no octupole deformed nuclei for Z =112 -126 in covariant DFT calculations. This agrees with Skyrme DFT calculations, but disagrees with Gogny DFT and microscopic+macroscopic calculations which predict an extended Z ˜120 , N ˜190 region of octupole deformation.

  16. High-K multi-quasiparticle states in 254No

    NASA Astrophysics Data System (ADS)

    Clark, R. M.; Gregorich, K. E.; Berryman, J. S.; Ali, M. N.; Allmond, J. M.; Beausang, C. W.; Cromaz, M.; Deleplanque, M. A.; Dragojević, I.; Dvorak, J.; Ellison, P. A.; Fallon, P.; Garcia, M. A.; Gates, J. M.; Gros, S.; Jeppesen, H. B.; Kaji, D.; Lee, I. Y.; Macchiavelli, A. O.; Morimoto, K.; Nitsche, H.; Paschalis, S.; Petri, M.; Stavsetra, L.; Stephens, F. S.; Watanabe, H.; Wiedeking, M.

    2010-06-01

    We report results from an experiment on the decay of the high-K isomers in 254No. We have been able to establish the decay from the known high-lying four-quasiparticle isomer, which we assign as a K=16 state at an excitation energy of Ex=2.928(3) MeV. The decay of this state passes through a rotational band based on a previously unobserved state at Ex=2.012(2) MeV, which we suggest is based on a two-quasineutron configuration with K=10. This state in turn decays to a rotational band based on the known K=8 isomer, which we infer must also have a two quasineutron configuration. We are able to assign many new gamma-rays associated with the decay of the K=8 isomer, including the identification of a highly K-forbidden ΔK=8 E1 transition to the ground-state band. These results provide valuable new information on the orbitals close to the Fermi surface, pairing correlations, deformation and rotational response, and K-conservation in nuclei of the deformed trans-fermium region.

  17. High Temperature Monotonic and Cyclic Deformation in a Directionally Solidified Nickel-Base Superalloy.

    DTIC Science & Technology

    1986-05-01

    discuss mechanisms of deformation including slip mode, strain softening/hardening, and grain boundary effects. Antolovich (4) discussed high...cracking at lower frequencies, for a given number of cycles. Antolovich et. al. (83,85) determined the life to be a trade-off between structural coarsenig...The stability of the precipitate is important in high temperature LCF. As reviewed by Antolovich and Jayaraman (48), it depends on misfit and

  18. Nonlinear viscoelastic response of highly filled elastomers under multiaxial finite deformation

    NASA Technical Reports Server (NTRS)

    Peng, Steven T. J.; Landel, Robert F.

    1990-01-01

    A biaxial tester was used to obtain precise biaxial stress responses of highly filled, high strain capability elastomers. Stress-relaxation experiments show that the time-dependent part of the relaxation response can be reasonably approximated by a function which is strain and biaxiality independent. Thus, isochronal data from the stress-relaxation curves can be used to determine the stored energy density function. The complex behavior of the elastomers under biaxial deformation may be caused by dewetting.

  19. Combination of metamorphism and deformation affect the nano-scale pore structures and macromolecule characteristics of high-rank deformed coals

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Li, H.; Ju, Y.

    2013-12-01

    Coal constitutes a large proportion of total energy supply in the world. Coalbed Methane (CBM) composes the greenhouse gases, which has attracted more and more scientists' concern and attention. The adsorption/desorption characteristics and mechanism of CBM on high-rank deformed coals are in favor of enhancing gas recovery, reducing coal mining accidents and carbon emission. Although the influence factors of CBM adsorption/desorption on different coals have been intensively studied, the combined action of metamorphism and deformation on high-rank coals have been rarely researched. Nevertheless. Metamorphism and deformation are the most fundamental driving forces that cause the changes of inner structures and compositions in coal strata, and then alter the adsorption/desorption capacities of CBM on different coalbeds. South of Qinshui Basin in Shanxi province developed with abundant high-rank coals is the first demonstrate area of CBM development in China. Meanwhile Southwest of Fujian province represents high metamorphic-deformed coals region due to the intense volcanic activities. Therefore samples were taken in both areas to elaborate the adsorption/desorption characteristics and mechanism of CBM. Based on hand specimens description, coal macerals testing, proximate analysis, ultimate analysis and vitrinite reflectance testing, the physical properties and composition characteristics of high-rank deformed coals have been studied. Combined with liquid nitrogen adsorption experiments, Transmission Electron Microscopy (TEM) observation, Fourier Transform Infrared Spectrometry (FTIR) and Nuclear Magnetic Resonance (NMR) experiments, the results show that nano-pores increase and become homogenization with metamorphic-deformation enhancement, stacking of the macromolecular basic structural units (BSU) enhances, aromatic compound increases while aliphatic chain compound and oxygen-containing function groups decrease. Comparing to coal adsorption/desorption isotherm

  20. Wavelet analysis deformation monitoring data of high-speed railway bridge

    NASA Astrophysics Data System (ADS)

    Tang, ShiHua; Huang, Qing; Zhou, Conglin; Xu, HongWei; Liu, YinTao; Li, FeiDa

    2015-12-01

    Deformation monitoring data of high-speed railway bridges will inevitably be affected because of noise pollution, A deformation monitoring point of high-speed railway bridge was measurd by using sokkia SDL30 electronic level for a long time,which got a large number of deformation monitoring data. Based on the characteristics of the deformation monitoring data of high-speed railway bridge, which contain lots of noise. Based on the MATLAB software platform, 120 groups of deformation monitoring data were applied to analysis of wavelet denoising.sym6,db6 wavelet basis function were selected to analyze and remove the noise.The original signal was broken into three layers wavelet,which contain high frequency coefficients and low frequency coefficients.However, high frequency coefficient have plenty of noise.Adaptive method of soft and hard threshold were used to handle in the high frequency coefficient.Then,high frequency coefficient that was removed much of noise combined with low frequency coefficient to reconstitute and obtain reconstruction wavelet signal.Root Mean Square Error (RMSE) and Signal-To-Noise Ratio (SNR) were regarded as evaluation index of denoising,The smaller the root mean square error and the greater signal-to-noise ratio indicate that them have a good effect in denoising. We can surely draw some conclusions in the experimental analysis:the db6 wavelet basis function has a good effect in wavelet denoising by using a adaptive soft threshold method,which root mean square error is minimum and signal-to-noise ratio is maximum.Moreover,the reconstructed image are more smooth than original signal denoising after wavelet denoising, which removed noise and useful signal are obtained in the original signal.Compared to the other three methods, this method has a good effect in denoising, which not only retain useful signal in the original signal, but aiso reach the goal of removing noise. So, it has a strong practical value in a actual deformation monitoring

  1. High-pressure and high temperature deformation studies of polycrystalline diamond

    NASA Astrophysics Data System (ADS)

    Yu, X.; Zhang, J.; Xu, H.; Wang, L.; Zhao, Y.

    2010-12-01

    With a Vicker’s hardness up to 120 GPa, diamond is the hardest material known to mankind. Diamond also has the highest bulk modulus (443 GPa) and the highest shear modulus (535 GPa) among all materials. However, because diamond is difficult to deform, little is known to date with regard to its constitutive properties such as yield strength and flow stress. In this work, we present results obtained at X17B2 of NSLS using the deformation-DIA (D-DIA) on cylindrical polycrystalline diamond at different pressure and temperature conditions. As expected, even at total axial strains up to 30%, we did not observe the yield point of diamond at room temperature and a confining pressure of 4 GPa. However, for deformation at 1000 and 1200 C, we observed an ultimate plastic flow of diamond at total axial strains of 10% and 5%, respectively, indicating that diamond weakens rapidly when temperature is over 1000 C. We further derived the microscopic stress of diamond during the deformation from the peak profile analysis, and we found that the microscopic and macroscopic stresses show similar variations with the total axial strain at both room temperature and 1000 C. However, at 1200 C, the microscopic stress remains fairly constant in the entire course of deformation, indicating that the stress at this higher temperature is uniformly distributed within polycrystalline diamond particles during the deformation. We also carried out SEM and TEM studies on the recovered samples to investigate their miscrostructures, and we find that the grain size of diamond decreases substantially during the deformation, from the initial 4-6 microns to sub-microns. More details of the experimental results will be presented and discussed.

  2. Spontaneous electric current flow during deformation of non-piezoelectric marble samples: an indicator of stress state?

    NASA Astrophysics Data System (ADS)

    Cartwright-Taylor, A. L.; Sammonds, P. R.; Vallianatos, F.

    2016-12-01

    We recorded spontaneous electric current flow in non-piezoelectric Carrara marble samples during triaxial deformation. Mechanical data, ultrasonic velocities and acoustic emissions were acquired simultaneously with electric current to constrain the relationship between electric current flow, differential stress and damage. Under strain-controlled loading, spontaneous electric current signals (nA) were generated and sustained under all conditions tested. In dry samples, a detectable electric current arises only during dilatancy and is correlated with the damage induced by microcracking. Signal variations with confining pressure correspond to microcrack suppression, while variations with strain rate are associated with time-dependent differences in deformation mechanism across the brittle to semi-brittle transition. In the brittle regime, the signal exhibits a precursory change as damage localises and the stress drop accelerates towards failure. This change is particularly distinct at dynamic strain rates. Similar changes are seen in the semi-brittle regime although the signal is more oscillatory in nature. Current flow in dry samples is proportional to stress within 90% of peak stress. In fluid-saturated samples proportionality holds from 40% peak stress, with a significant increase in the rate of current production from 90% peak stress associated with fluid flow during dilatancy. This direct relationship demonstrates that electric current could be used as a proxy for stress, indicating when the rock is reaching the limit of its strength. The experimental power law relationship between electric current and strain rate, which mirrors the power-law creep equation, supports this observation. High-frequency fluctuations of electric current are not normally distributed - they exhibit `heavy-tails'. We model these distributions with q-Gaussian statistics and evolution of the q-parameter during deformation reveals a two-stage precursory anomaly prior to sample failure

  3. The Difference of Structural State and Deformation Behavior between Teenage and Mature Human Dentin

    PubMed Central

    Panfilov, Peter; Zaytsev, Dmitry; Antonova, Olga V.; Alpatova, Victoria; Kiselnikova, Larissa P.

    2016-01-01

    Objective. The cause of considerable elasticity and plasticity of human dentin is discussed in the relationship with its microstructure. Methods. Structural state of teenage and mature human dentin is examined by using XRD and TEM techniques, and their deformation behavior under compression is studied as well. Result. XRD study has shown that crystallographic type of calcium hydroxyapatite in human dentin (calcium hydrogen phosphate hydroxide Ca9HPO4(PO4)5OH; Space Group P63/m (176); a = 9,441 A; c = 6,881 A; c/a = 0,729; Crystallite (Scherrer) 200 A) is the same for these age groups. In both cases, dentin matrix is X-ray amorphous. According to TEM examination, there are amorphous and ultrafine grain phases in teenage and mature dentin. Mature dentin is stronger on about 20% than teenage dentin, while teenage dentin is more elastic on about 20% but is less plastic on about 15% than mature dentin. Conclusion. The amorphous phase is dominant in teenage dentin, whereas the ultrafine grain phase becomes dominant in mature dentin. Mechanical properties of human dentin under compression depend on its structural state, too. PMID:26989416

  4. The Difference of Structural State and Deformation Behavior between Teenage and Mature Human Dentin.

    PubMed

    Panfilov, Peter; Zaytsev, Dmitry; Antonova, Olga V; Alpatova, Victoria; Kiselnikova, Larissa P

    2016-01-01

    Objective. The cause of considerable elasticity and plasticity of human dentin is discussed in the relationship with its microstructure. Methods. Structural state of teenage and mature human dentin is examined by using XRD and TEM techniques, and their deformation behavior under compression is studied as well. Result. XRD study has shown that crystallographic type of calcium hydroxyapatite in human dentin (calcium hydrogen phosphate hydroxide Ca9HPO4(PO4)5OH; Space Group P63/m (176); a = 9,441 A; c = 6,881 A; c/a = 0,729; Crystallite (Scherrer) 200 A) is the same for these age groups. In both cases, dentin matrix is X-ray amorphous. According to TEM examination, there are amorphous and ultrafine grain phases in teenage and mature dentin. Mature dentin is stronger on about 20% than teenage dentin, while teenage dentin is more elastic on about 20% but is less plastic on about 15% than mature dentin. Conclusion. The amorphous phase is dominant in teenage dentin, whereas the ultrafine grain phase becomes dominant in mature dentin. Mechanical properties of human dentin under compression depend on its structural state, too.

  5. The Deformity Angular Ratio: Does It Correlate With High-Risk Cases for Potential Spinal Cord Monitoring Alerts in Pediatric 3-Column Thoracic Spinal Deformity Corrective Surgery?

    PubMed

    Lewis, Noah D H; Keshen, Sam G N; Lenke, Lawrence G; Zywiel, Michael G; Skaggs, David L; Dear, Taylor E; Strantzas, Samuel; Lewis, Stephen J

    2015-08-01

    A retrospective analysis. The purpose of this study was to determine whether the deformity angular ratio (DAR) can reliably assess the neurological risks of patients undergoing deformity correction. Identifying high-risk patients and procedures can help ensure that appropriate measures are taken to minimize neurological complications during spinal deformity corrections. Subjectively, surgeons look at radiographs and evaluate the riskiness of the procedure. However, 2 curves of similar magnitude and location can have significantly different risks of neurological deficit during surgery. Whether the curve spans many levels or just a few can significantly influence surgical strategies. Lenke et al have proposed the DAR, which is a measure of curve magnitude per level of deformity. The data from 35 pediatric spinal deformity correction procedures with thoracic 3-column osteotomies were reviewed. Measurements from preoperative radiographs were used to calculate the DAR. Binary logistic regression was used to model the relationship between DARs (independent variables) and presence or absence of an intraoperative alert (dependent variable). In patients undergoing 3-column osteotomies, sagittal curve magnitude and total curve magnitude were associated with increased incidence of transcranial motor evoked potential changes. Total DAR greater than 45° per level and sagittal DAR greater than 22° per level were associated with a 75% incidence of a motor evoked potential alert, with the incidence increasing to 90% with sagittal DAR of 28° per level. In patients undergoing 3-column osteotomies for severe spinal deformities, the DAR was predictive of patients developing intraoperative motor evoked potential alerts. Identifying accurate radiographical, patient, and procedural risk factors in the correction of severe deformities can help prepare the surgical team to improve safety and outcomes when carrying out complex spinal corrections. 3.

  6. Large-deformation and high-strength amorphous porous carbon nanospheres

    PubMed Central

    Yang, Weizhu; Mao, Shimin; Yang, Jia; Shang, Tao; Song, Hongguang; Mabon, James; Swiech, Wacek; Vance, John R.; Yue, Zhufeng; Dillon, Shen J.; Xu, Hangxun; Xu, Baoxing

    2016-01-01

    Carbon is one of the most important materials extensively used in industry and our daily life. Crystalline carbon materials such as carbon nanotubes and graphene possess ultrahigh strength and toughness. In contrast, amorphous carbon is known to be very brittle and can sustain little compressive deformation. Inspired by biological shells and honeycomb-like cellular structures in nature, we introduce a class of hybrid structural designs and demonstrate that amorphous porous carbon nanospheres with a thin outer shell can simultaneously achieve high strength and sustain large deformation. The amorphous carbon nanospheres were synthesized via a low-cost, scalable and structure-controllable ultrasonic spray pyrolysis approach using energetic carbon precursors. In situ compression experiments on individual nanospheres show that the amorphous carbon nanospheres with an optimized structure can sustain beyond 50% compressive strain. Both experiments and finite element analyses reveal that the buckling deformation of the outer spherical shell dominates the improvement of strength while the collapse of inner nanoscale pores driven by twisting, rotation, buckling and bending of pore walls contributes to the large deformation. PMID:27072412

  7. Review of Relationship Between Particle Deformation, Coating Microstructure, and Properties in High-Pressure Cold Spray

    NASA Astrophysics Data System (ADS)

    Rokni, M. R.; Nutt, S. R.; Widener, C. A.; Champagne, V. K.; Hrabe, R. H.

    2017-08-01

    In the cold spray (CS) process, deposits are produced by depositing powder particles at high velocity onto a substrate. Powders deposited by CS do not undergo melting before or upon impacting the substrate. This feature makes CS suitable for deposition of a wide variety of materials, most commonly metallic alloys, but also ceramics and composites. During processing, the particles undergo severe plastic deformation and create a more mechanical and less metallurgical bond with the underlying material. The deformation behavior of an individual particle depends on multiple material and process parameters that are classified into three major groups—powder characteristics, geometric parameters, and processing parameters, each with their own subcategories. Changing any of these parameters leads to evolution of a different microstructure and consequently changes the mechanical properties in the deposit. While cold spray technology has matured during the last decade, the process is inherently complex, and thus, the effects of deposition parameters on particle deformation, deposit microstructure, and mechanical properties remain unclear. The purpose of this paper is to review the parameters that have been investigated up to now with an emphasis on the existent relationships between particle deformation behavior, microstructure, and mechanical properties of various cold spray deposits.

  8. High Resolution Deformation Time Series Estimation for Distributed Scatterers Using Terrasar-X Data

    NASA Astrophysics Data System (ADS)

    Goel, K.; Adam, N.

    2012-07-01

    In recent years, several SAR satellites such as TerraSAR-X, COSMO-SkyMed and Radarsat-2 have been launched. These satellites provide high resolution data suitable for sophisticated interferometric applications. With shorter repeat cycles, smaller orbital tubes and higher bandwidth of the satellites; deformation time series analysis of distributed scatterers (DSs) is now supported by a practical data basis. Techniques for exploiting DSs in non-urban (rural) areas include the Small Baseline Subset Algorithm (SBAS). However, it involves spatial phase unwrapping, and phase unwrapping errors are typically encountered in rural areas and are difficult to detect. In addition, the SBAS technique involves a rectangular multilooking of the differential interferograms to reduce phase noise, resulting in a loss of resolution and superposition of different objects on ground. In this paper, we introduce a new approach for deformation monitoring with a focus on DSs, wherein, there is no need to unwrap the differential interferograms and the deformation is mapped at object resolution. It is based on a robust object adaptive parameter estimation using single look differential interferograms, where, the local tilts of deformation velocity and local slopes of residual DEM in range and azimuth directions are estimated. We present here the technical details and a processing example of this newly developed algorithm.

  9. Review of Relationship Between Particle Deformation, Coating Microstructure, and Properties in High-Pressure Cold Spray

    NASA Astrophysics Data System (ADS)

    Rokni, M. R.; Nutt, S. R.; Widener, C. A.; Champagne, V. K.; Hrabe, R. H.

    2017-06-01

    In the cold spray (CS) process, deposits are produced by depositing powder particles at high velocity onto a substrate. Powders deposited by CS do not undergo melting before or upon impacting the substrate. This feature makes CS suitable for deposition of a wide variety of materials, most commonly metallic alloys, but also ceramics and composites. During processing, the particles undergo severe plastic deformation and create a more mechanical and less metallurgical bond with the underlying material. The deformation behavior of an individual particle depends on multiple material and process parameters that are classified into three major groups—powder characteristics, geometric parameters, and processing parameters, each with their own subcategories. Changing any of these parameters leads to evolution of a different microstructure and consequently changes the mechanical properties in the deposit. While cold spray technology has matured during the last decade, the process is inherently complex, and thus, the effects of deposition parameters on particle deformation, deposit microstructure, and mechanical properties remain unclear. The purpose of this paper is to review the parameters that have been investigated up to now with an emphasis on the existent relationships between particle deformation behavior, microstructure, and mechanical properties of various cold spray deposits.

  10. Large-deformation and high-strength amorphous porous carbon nanospheres

    NASA Astrophysics Data System (ADS)

    Yang, Weizhu; Mao, Shimin; Yang, Jia; Shang, Tao; Song, Hongguang; Mabon, James; Swiech, Wacek; Vance, John R.; Yue, Zhufeng; Dillon, Shen J.; Xu, Hangxun; Xu, Baoxing

    2016-04-01

    Carbon is one of the most important materials extensively used in industry and our daily life. Crystalline carbon materials such as carbon nanotubes and graphene possess ultrahigh strength and toughness. In contrast, amorphous carbon is known to be very brittle and can sustain little compressive deformation. Inspired by biological shells and honeycomb-like cellular structures in nature, we introduce a class of hybrid structural designs and demonstrate that amorphous porous carbon nanospheres with a thin outer shell can simultaneously achieve high strength and sustain large deformation. The amorphous carbon nanospheres were synthesized via a low-cost, scalable and structure-controllable ultrasonic spray pyrolysis approach using energetic carbon precursors. In situ compression experiments on individual nanospheres show that the amorphous carbon nanospheres with an optimized structure can sustain beyond 50% compressive strain. Both experiments and finite element analyses reveal that the buckling deformation of the outer spherical shell dominates the improvement of strength while the collapse of inner nanoscale pores driven by twisting, rotation, buckling and bending of pore walls contributes to the large deformation.

  11. Plastic Deformation of Micromachined Silicon Diaphragms with a Sealed Cavity at High Temperatures

    PubMed Central

    Ren, Juan; Ward, Michael; Kinnell, Peter; Craddock, Russell; Wei, Xueyong

    2016-01-01

    Single crystal silicon (SCS) diaphragms are widely used as pressure sensitive elements in micromachined pressure sensors. However, for harsh environments applications, pure silicon diaphragms are hardly used because of the deterioration of SCS in both electrical and mechanical properties. To survive at the elevated temperature, the silicon structures must work in combination with other advanced materials, such as silicon carbide (SiC) or silicon on insulator (SOI), for improved performance and reduced cost. Hence, in order to extend the operating temperatures of existing SCS microstructures, this work investigates the mechanical behavior of pressurized SCS diaphragms at high temperatures. A model was developed to predict the plastic deformation of SCS diaphragms and was verified by the experiments. The evolution of the deformation was obtained by studying the surface profiles at different anneal stages. The slow continuous deformation was considered as creep for the diaphragms with a radius of 2.5 mm at 600 °C. The occurrence of plastic deformation was successfully predicted by the model and was observed at the operating temperature of 800 °C and 900 °C, respectively. PMID:26861332

  12. Large-deformation and high-strength amorphous porous carbon nanospheres.

    PubMed

    Yang, Weizhu; Mao, Shimin; Yang, Jia; Shang, Tao; Song, Hongguang; Mabon, James; Swiech, Wacek; Vance, John R; Yue, Zhufeng; Dillon, Shen J; Xu, Hangxun; Xu, Baoxing

    2016-04-13

    Carbon is one of the most important materials extensively used in industry and our daily life. Crystalline carbon materials such as carbon nanotubes and graphene possess ultrahigh strength and toughness. In contrast, amorphous carbon is known to be very brittle and can sustain little compressive deformation. Inspired by biological shells and honeycomb-like cellular structures in nature, we introduce a class of hybrid structural designs and demonstrate that amorphous porous carbon nanospheres with a thin outer shell can simultaneously achieve high strength and sustain large deformation. The amorphous carbon nanospheres were synthesized via a low-cost, scalable and structure-controllable ultrasonic spray pyrolysis approach using energetic carbon precursors. In situ compression experiments on individual nanospheres show that the amorphous carbon nanospheres with an optimized structure can sustain beyond 50% compressive strain. Both experiments and finite element analyses reveal that the buckling deformation of the outer spherical shell dominates the improvement of strength while the collapse of inner nanoscale pores driven by twisting, rotation, buckling and bending of pore walls contributes to the large deformation.

  13. Finite element analysis of low-cost membrane deformable mirrors for high-order adaptive optics

    NASA Astrophysics Data System (ADS)

    Winsor, Robert S.; Sivaramakrishnan, Anand; Makidon, Russell B.

    1999-10-01

    We demonstrate the feasibility of glass membrane deformable mirror (DM) support structures intended for very high order low-stroke adaptive optics systems. We investigated commercially available piezoelectric ceramics. Piezoelectric tubes were determined to offer the largest amount of stroke for a given amount of space on the mirror surface that each actuator controls. We estimated the minimum spacing and the maximum expected stroke of such actuators. We developed a quantitative understanding of the response of a membrane mirror surface by performing a Finite Element Analysis (FEA) study. The results of the FEA analysis were used to develop a design and fabrication process for membrane deformable mirrors of 200 - 500 micron thicknesses. Several different values for glass thickness and actuator spacing were analyzed to determine the best combination of actuator stoke and surface deformation quality. We considered two deformable mirror configurations. The first configuration uses a vacuum membrane attachment system where the actuator tubes' central holes connect to an evacuated plenum, and atmospheric pressure holds the membrane against the actuators. This configuration allows the membrane to be removed from the actuators, facilitating easy replacement of the glass. The other configuration uses precision bearing balls epoxied to the ends of the actuator tubes, with the glass membrane epoxied to the ends of the ball bearings. While this kind of DM is not serviceable, it allows actuator spacings of 4 mm, in addition to large stroke. Fabrication of a prototype of the latter kind of DM was started.

  14. High-temperature tensile deformation behavior of aluminum oxide with and without an applied electric field

    NASA Astrophysics Data System (ADS)

    Campbell, James

    1998-12-01

    Ceramics are usually considered to be brittle, but under certain conditions some ceramics exhibit a large degree of ductility. They are fine-grained and exhibit superplastic behavior when deformed at high temperatures and low stresses. Whereas superplasticity gives enhanced ductility to metals, it may be the only method for imparting large plasticity to ceramics. Electric fields have been shown to increase ductility, reduce flow stress and reduce cavitation in the superplastic forming of 7475 Al and yttria-stabilized zirconia. Thus, the concurrent application of an electric field may give improved superplastic properties and increased plasticity to a marginally ductile ceramic such as aluminum oxide (alpha-alumina). Fine-grained alumina tensile specimens, formed by dry pressing and sintering a spray-dried powder, were tested in tension at high temperature with and without an electric field of 300 V/cm. Constant strain rate, strain rate cycling and stress relaxation tests were performed. The effects of an electric field on the ductility, flow stress, cavitation and parameters of the Weertman-Dorn deformation equation were measured. Without an electric field, the following deformation parameters were found: the stress exponent n = 2.2, the grain size exponent p = 1.9, the activation energy Q = 490 kJ/mol and the threshold stress sigmao ≈ 0 MPa, indicating structural superplasticity where grain boundary sliding is the predominant deformation mode and was likely accommodated by the motion of grain boundary dislocations. An electric field of 300 V/cm gave a Joule heating temperature increase of ˜30°C and caused the alumina to swell 5--25% (increasing with time), even while under no applied stress, thereby reducing its ductility and flow stress. After correcting for Joule heating and swelling there was still a significant flow stress reduction produced by the field and the following deformation parameters were found: n = 2.2, p = 1.9, Q = 950 kJ/mol and sigmao ≈ 0

  15. The large volume press facility at ID06 beamline of the European synchrotron radiation facility as a High Pressure-High Temperature deformation apparatus.

    PubMed

    Guignard, Jeremy; Crichton, Wilson A

    2015-08-01

    We report here the newly developed deformation setup offered by the 20MN (2000T) multi-anvil press newly installed at sector 7 of the European synchrotron radiation facility, on the ID06 beamline. The press is a Deformation-DIA (D-DIA) type apparatus, and different sets of primary anvils can be used for deformation experiments, from 6 mm to 3 mm truncations, according to the target pressure needed. Pressure and temperature calibrations and gradients show that the central zone of the assemblies is stable. Positions of differential RAMs are controlled with a sub-micron precision allowing strain rate from 10(-4) to 10(-6) s(-1). Moreover, changing differential RAM velocity is immediately visible on sample, making faster reaching of steady state. Lattice stresses are determined by the shifting of diffraction peak with azimuth angle using a linear detector covering typically a 10° solid-angle in 2θ mounted on rotation perpendicular to the beam. Acquisition of diffraction pattern, at a typical energy of 55 keV, is less than a minute to cover the whole azimuth-2θ space. Azimuth and d-spacing resolution are respectively better than 1° and 10(-3) Å making it possible to quantify lattice stresses with a precision of ±20 MPa (for silicates, which have typically high values of elastic properties), in pure or simple shear deformation measurements. These mechanical data are used to build fully constrained flow laws by varying P-T-σ-ε̇ conditions with the aim to better understanding the rheology of Earth's mantle. Finally, through texture analysis, it is also possible to determine lattice preferred orientation during deformation by quantifying diffraction peak intensity variation with azimuth angle. This press is therefore included as one of the few apparatus that can perform such experiments combining with synchrotron radiation.

  16. Grain size effects on the high strain rate deformation of copper

    NASA Astrophysics Data System (ADS)

    Stevenson, Michael Earle

    The high strain rate (>104/s) mechanical properties of OFHC copper were studied by the Taylor impact test for a series of copper grain sizes from 31 to 152 mum. The results are analyzed by both analytical and finite element. There is a significant increase in the dynamic strength of OFHC copper for strain rates greater than approximately 104/s. This strength increase is also dependent upon the grain size of the OFHC copper prior to testing and follows a classical Hall-Petch relationship. In addition to the analytical and finite element models, a universal dynamic stress-strain curve was developed and constructed for each grain size of the OFHC copper. The characterization parameters determined from the universal dynamic stress-strain curve are also grain size dependent. Many of these parameters also follow the classical Hall-Petch trend. Post-impact microstructures of the copper can be generalized into five distinct regions. Beginning at the specimen impact face, those regions are: (i) a nanocrystalline, or sub-micron grain size layer; (ii) a dynamically recrystallized region; (iii) a region of high density (111)[112¯] twinning; (iv) a section dominated by dislocation plastic flow, or slip and (v) the specimen portion where the deformation is completely elastic. The five regions can be related to the mechanical properties derived from the individual models and the universal dynamic stress-strain curve with consideration of the initial microstructure of the copper. The results of this dissertation suggest that there is a direct linkage between the dynamic mechanical state of stress during the impact tests and both the initial and final metallurgical microstructures of the copper.

  17. Structural relationships and lithologic deformation partitioning of the Sevier, Laramide, Mid-Tertiary and Basin and Range deformations in the High Plateaus of southwestern Utah

    SciTech Connect

    Nickelsen, R.P. . Geology Dept.)

    1993-03-01

    A Mid-Tertiary horizontal compression, verging radially toward Az 120 to 215 and extending E-W for 90 km across the High Plateaus of SW Utah, was driven by intrusions and/or gravitational spreading of the Marysvale volcanic field, 40-60 km to the north. Structures of this deformation overprint a NNW trending Laramide monocline on the east, and are overprinted by NNE trending Basin and Range extensional structures. To the west at the Sevier deformation front, Mid-Tertiary compressional structures are directed Az 205, but no Sevier foreland deformation was found. Small scale structures of the Laramide, Mid-Tertiary, and Basin and Range deformations are partitioned lithologically in four rock types of different properties: (1) Friable Cretaceous sands contain Laramide and Mid-Tertiary conjugate compressional sand shear wedges or Laramide and Basin and Range conjugate, extensional sand shears; (2) Calcareous Cretaceous sandstones or Eocene Claron Fm limestones contain both conjugate compressional wedge faults and strike-slip faults; (3) spaced dissolution cleavage occurs only in Claron limestones; (4) cretaceous coals contain Mid-Tertiary joints (cleat) at distal locations. A Mid-Tertiary layer-parallel strain gradient toward the SE-S-SSW is marked by deformation fronts in the four rock types where conjugate faults, spaced cleavage, sand shears and joints in coal successively disappear.

  18. High-speed quantitative phase imaging of dynamic thermal deformation in laser irradiated films

    NASA Astrophysics Data System (ADS)

    Taylor, Lucas N.; Brown, Andrew K.; Olson, Kyle D.; Talghader, Joseph J.

    2015-11-01

    We present a technique for high-speed imaging of the dynamic thermal deformation of transparent substrates under high-power laser irradiation. Traditional thermal sensor arrays are not fast enough to capture thermal decay events. Our system adapts a Mach-Zender interferometer, along with a high-speed camera to capture phase images on sub-millisecond time-scales. These phase images are related to temperature by thermal expansion effects and by the change of refractive index with temperature. High power continuous-wave and long-pulse laser damage often hinges on thermal phenomena rather than the field-induced effects of ultra-short pulse lasers. Our system was able to measure such phenomena. We were able to record 2D videos of 1 ms thermal deformation waves, with 6 frames per wave, from a 100 ns, 10 mJ Q-switched Nd:YAG laser incident on a yttria-coated glass slide. We recorded thermal deformation waves with peak temperatures on the order of 100 degrees Celsius during non-destructive testing.

  19. Atomic force microscopic study of the structure of high-density polyethylene deformed in liquid medium by crazing mechanism.

    PubMed

    Bagrov, D V; Yarysheva, A Y; Rukhlya, E G; Yarysheva, L M; Volynskii, A L; Bakeev, N F

    2014-02-01

    A procedure has been developed for the direct atomic force microscopic (AFM) examination of the native structure of high-density polyethylene (HDPE) deformed in an adsorption-active liquid medium (AALM) by the crazing mechanism. The AFM investigation has been carried out in the presence of a liquid medium under conditions preventing deformed films from shrinkage. Deformation of HDPE in AALM has been shown to proceed through the delocalized crazing mechanism and result in the development of a fibrillar-porous structure. The structural parameters of the crazed polymer have been determined. The obtained AFM images demonstrate a nanosized nonuniformity of the deformation and enable one to observe the structural rearrangements that take place in the deformed polymer after removal of the liquid medium and stress relaxation. A structural similarity has been revealed between HDPE deformed in the AALM and hard elastic polymers.

  20. Effect of prior deformation on microstructural development and Laves phase precipitation in high-chromium stainless steel.

    PubMed

    Hsiao, Z-W; Chen, D; Kuo, J-C; Lin, D-Y

    2017-04-01

    This study investigated the influence of deformation on precipitation behaviour and microstructure change during annealing. Here, the prior deformation of high-chromium stainless steel was tensile deformation of 3%, 6% and 10%, and the specimens were then annealed at 700˚C for 10 h. The specimens were subsequently analyzed using backscattered electron image and electron backscattering diffraction measurements with SEM. Compared with the deformation microstructure, the grains revealed no preferred orientation. The precipitates of TiN and NbC were formed homogenously in the grain interior and at grain boundaries after annealing. Fine Laves phase precipitates were observed in grains and along subgrain boundaries as the deformation increased. Furthermore, the volume fraction of Laves phase increased, but the average particle diameter of precipitate was reduced as the deformation increased.

  1. Deformation behaviour and 6H-LPSO structure formation at nanoindentation in lamellar high Nb containing TiAl alloy

    NASA Astrophysics Data System (ADS)

    Song, L.; Xu, X. J.; Peng, C.; Wang, Y. L.; Liang, Y. F.; Shang, S. L.; Liu, Z. K.; Lin, J. P.

    2015-02-01

    Microstructure and deformation mechanisms at a nanoindentation in the lamellar colony of high Nb containing TiAl alloy have been studied using the focused ion beam and the transmission electron microscopy. Considerable deformation twins are observed around the nanoindentation, and a strain gradient is generated. A continuous change in the bending angle of the lamellar structure can be derived, and a strain-induced grain refinement process is observed as various active deformations split the γ grains into subgrains. In addition to all possible deformation mechanisms (ordinary dislocation, super-dislocation and deformation twining) activated due to the heavy plastic deformation, a 6-layer hexagonal (6H) long-period stacking ordered structure is identified for the first time near the contact zone and is thought to be closely related to the glide of partial dislocations.

  2. Use of Terrestrial Laser Scanning Technology for Long Term High Precision Deformation Monitoring

    PubMed Central

    Vezočnik, Rok; Ambrožič, Tomaž; Sterle, Oskar; Bilban, Gregor; Pfeifer, Norbert; Stopar, Bojan

    2009-01-01

    The paper presents a new methodology for high precision monitoring of deformations with a long term perspective using terrestrial laser scanning technology. In order to solve the problem of a stable reference system and to assure the high quality of possible position changes of point clouds, scanning is integrated with two complementary surveying techniques, i.e., high quality static GNSS positioning and precise tacheometry. The case study object where the proposed methodology was tested is a high pressure underground pipeline situated in an area which is geologically unstable. PMID:22303152

  3. High Le Fort I osteotomy for correction of mid-face deformity in Crouzon syndrome.

    PubMed

    Nakajima, Yasumichi; Nakano, Hiroyuki; Sumida, Tomoki; Yamada, Tomohiro; Inoue, Kazuya; Sugiyama, Goro; Mishima, Katsuaki; Mori, Yoshihide

    2016-09-01

    An 18-year-old woman with mild Crouzon syndrome was referred with malocclusion and mandibular protrusion. Examination revealed Class III canine and molar relationships, hypoplastic maxilla, 1-mm overbite, and -2-mm overjet. Analysis showed 69° sella-nasion-A, 73.6° sella-nasion-B, and -4.6° A point-nasion-B point angles. Polysomnography revealed respiratory disturbance and 6.3% oxygen desaturation indices of 5.4/h and 9.0/h. We performed double-jaw surgery using high Le Fort I osteotomy and bilateral sagittal split ramus osteotomy for midfacial deformity correction. Twelve months post-surgery, her measures were 70.8°, 72°, -1.2°, 3.0/h, and 6.1/h, respectively. Esthetics were satisfactory. High Le Fort I osteotomy is effective for midfacial deformity correction in patients with Crouzon syndrome. © 2016 Japanese Teratology Society.

  4. Deformable mirrors for intra-cavity use in high-power thin-disk lasers.

    PubMed

    Piehler, Stefan; Dietrich, Tom; Wittmüss, Philipp; Sawodny, Oliver; Ahmed, Marwan Abdou; Graf, Thomas

    2017-02-20

    We present deformable mirrors for the intra-cavity use in high-power thin-disk laser resonators. The refractive power of these mirrors is continuously adaptable from -0.7 m-1 to 0.3 m-1, corresponding to radii of curvature ranging between 2.86 m (convex) and 6.67 m (concave). The optimized shape of the mirror membrane enables a very low peak-to-valley deviation from a paraboloid deformation over a large area. With the optical performance of our mirrors being equal to that of standard HR mirrors, we were able to demonstrate the tuning of the beam quality of a thin-disk laser in a range of M2 = 3 to M2 = 1 during laser operation at output powers as high as 1.1 kW.

  5. Characterization of deformable mirrors for high-order adaptive optics systems

    NASA Astrophysics Data System (ADS)

    Stuik, Remko; Hippler, Stefan; Feldt, Markus; Aceituno, Jesus; Egner, Sebastian E.

    2004-10-01

    Deformable mirrors with more than 1000 actuators are currently being developed for eXtreme AO applications, either for ELTs, high order Adaptive Optics correction in the visible light, or combination of both. The large number of actuators, the high frequency at which these DMs are to be used and further advancement in schemes for AO control, requiring a growing degree of knowledge of the AO system for efficient correction, sets special requirements on the characterization of the static and dynamic behavior of the DM. In the light of CHEOPS, an extreme-AO Planet Finder project, we have characterized a Xinetics deformable mirrors with 349 actuators. This mirror serves as a proxy for the characterization of a >1200 actuator DM of a similar type, which will be implemented in CHEOPS. In this paper we present the results of this characterization. Special attention was paid to mirror properties like hysteresis, non-linearity, temperature dependence and influence function.

  6. Structural and phase state and deformation behavior of the hydrogenated ultrafine-grained Zr-1Nb alloy

    NASA Astrophysics Data System (ADS)

    Stepanova, E. N.; Grabovetskaya, G. P.; Mishin, I. P.; Kudiiarov, V. N.

    2016-11-01

    The paper investigates the effect of hydrogenation towards the concentration of 0.33 wt % on the structural and phase state and the deformation process development during tension of the ultrafine-grained Zr-1 wt % Nb alloy (hereinafter Zr-1Nb) at the temperature range of 293-973 K. Hydrogen presence in the alloy in solid solution and hydride precipitates are found that results in an increase of its strength and plastic characteristics at room temperature. At elevated temperatures hydride dissolution activates dislocation motion that leads to strength characteristics reduction and to rise of deformation-to-failure.

  7. Steady state deformation of the Coso Range, east central California, inferred from satellite radar interferometry

    USGS Publications Warehouse

    Wicks, C.W.; Thatcher, W.; Monastero, F.C.; Hasting, M.A.

    2001-01-01

    Observations of deformation from 1992 to 1997 in the southern Coso Range using satellite radar interferometry show deformation rates of up to 35 mm yr-1 in an area ???10 km by 15 km. The deformation is most likely the result of subsidence in an area around the Coso geothermal field. The deformation signal has a short-wavelength component, related to production in the field, and a long-wavelength component, deforming at a constant rate, that may represent a source of deformation deeper than the geothermal reservoir. We have modeled the long-wavelength component of deformation and inferred a deformation source at ???4 km depth. The source depth is near the brittle-ductile transition depth (inferred from seismicity) and ???1.5 km above the top of the rhyolite magma body that was a source for the most recent volcanic eruption in the Coso volcanic field [Manley and Bacon, 2000]. From this evidence and results of other studies in the Coso Range, we interpret the source to be a leaking deep reservoir of magmatic fluids derived from a crystallizing rhyolite magma body.

  8. Hardness and phase analysis of IN 718 deformed at high strain rate.

    PubMed

    Renhof, L; Guder, S; Werner, E

    2004-06-01

    Specimens of the nickel base alloy IN 718 deformed at high strain rate (approximately 10 s(-1)), as realized in a screw press, have higher strength than parts forged conventionally in a hydraulic press. Microstructure analyses in light and transmission electron microscopes reveal the precipitation of very small Ni(3)Nb particles (gamma"-phase) to be the reason for the increased hardness. Several processing routes are discussed and analyzed in relation to the TTT-diagram of IN 718.

  9. Aluminium. II - A review of deformation properties of high purity aluminium and dilute aluminium alloys.

    NASA Technical Reports Server (NTRS)

    Reed, R. P.

    1972-01-01

    The elastic and plastic deformation behavior of high-purity aluminum and of dilute aluminum alloys is reviewed. Reliable property data, including elastic moduli, elastic coefficients, tensile, creep, fatigue, hardness, and impact are presented. Single crystal tensile results are discussed. Rather comprehensive reference lists, containing publications of the past 20 years, are included for each of the above categories. Defect structures and mechanisms responsible for mechanical behavior are presented. Strengthening techniques (alloys, cold work, irradiation, quenching, composites) and recovery are briefly reviewed.

  10. Present-day deformation across the Basin and Range Province, western United States

    USGS Publications Warehouse

    Thatcher, W.; Foulger, G.R.; Julian, B.R.; Svarc, J.; Quilty, E.; Bawden, G.W.

    1999-01-01

    The distribution of deformation within the Basin and Range province was determined from 1992, 1996, and 1998 surveys of a dense, 800-kilometer- aperture, Global Positioning System network, Internal deformation generally follows the pattern of Holocene fault distribution and is concentrated near the western extremity of the province, with lesser amounts focused near the eastern boundary. Little net deformation occurs across the central 500 kilometers of the network in western Utah and eastern Nevada. Concentration of deformation adjacent to the rigid Sierra Nevada block indicates that external plate-driving forces play an important role in driving deformation, modulating the extensional stress field generated by internal buoyancy forces that are due to lateral density gradients and topography near the province boundaries.

  11. Deformation and annealing behavior of heavily drawn oxygen-free high-conductivity (OFHC) copper

    NASA Astrophysics Data System (ADS)

    Waryoba, Daudi Rigenda

    Conductor wires used in pulsed high-field magnets require metallic materials with a beneficial combination of high mechanical strength to resist the Lorentz forces and high electrical conductivity to limit temperature excursions due to Joule heating. To achieve the required strength, most conductors are fabricated from microcomposite materials using the work hardening effect after heavy cold deformation such as wire drawing. Since the microstructure and texture of these microcomposites are complex, a detailed systematic study of these materials requires a separate study of the individual phases. This work presents a comprehensive study of the microstructure and microtexture evolution during deformation, and subsequent annealing of heavily deformed OFHC copper wires. Analytical tools used for investigation include optical microscopy, scanning electron microscopy (SEM), orientation-imaging microscopy (OIM) in SEM, and transmission electron microscopy (TEM). Mechanical properties were evaluated by tensile and microhardness testing. Some of the key features of the as-drawn wire are elongated grain size and shear bands. The intensity of the shear bands increased with strain. The ultimate tensile strength (UTS) and the microhardness of the heavily cold-drawn copper wires increased with strain, reached a saturation point and dropped at higher deformation strain. Deformation did not significantly alter the electrical conductivity of the wires. Deformed and recovered microstructures were characterized by a strong<111>+weak<100> duplex fiber texture. Nucleation of recrystallized grains occurred at shear bands and resulted in randomization of texture. On the other hand, recrystallization produced a strong<100>+weak<111>, which later changed to a <111> fiber texture during abnormal grain growth. A detailed analysis showed that recrystallization was a growth-controlled mechanism, and proceeds from the outer surface to the core. Interestingly, secondary recrystallization was

  12. Severe plastic deformation processing and high strain rate superplasticity in an aluminum matrix composite

    SciTech Connect

    Mishra, R.S.; McFadden, S.X.; Mukherjee, A.K.; Valiev, R.Z.; Islamgaliev, R.K.

    1999-04-23

    Metal matrix composites possess an attractive set of properties for structural applications. For example, reinforcement of conventional aluminum alloys with second phase ceramic particulates increases the stiffness, high temperature strength, etc. A drawback of ceramic phase reinforcement is that it makes machining of components difficult. Superplastic forming is quite attractive for hard-to-machine materials like composites. A number of aluminum matrix composites exhibit superplasticity. The most attractive feature of superplasticity in aluminum matrix composite is the high strain rate (10{sup {minus}2}--10{sup 1} s{sup {minus}1}) for optimum ductility. This is significantly higher than the optimum superplastic strain rates of 10{sup {minus}4}--10{sup {minus}3} s{sup {minus}1} in conventional fine grained alloys. The optimum superplasticity in aluminum matrix composites is influenced by the thermo-mechanical processing. In the last five years or so, a number of aluminum alloys have been processes by severe plastic deformation (SePD). Severe plastic deformation processing leads to ultrafine grained aluminum alloys with attractive superplastic properties. In this short paper the authors report on successful processing of an ultrafine grained aluminum matrix composite by severe plastic deformation technique. The SePD processes 2009 Al-SiC{sub 2} composite exhibits high strain rate superplasticity.

  13. Deformation Behavior of Cementite in Deformed High Carbon Steel Observed by X-ray Diffraction with Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Taniyama, Akira; Takayama, Toru; Arai, Masahiro; Hamada, Takanari

    2017-10-01

    The deformation behavior of cementite in drawn pearlitic steel and spheroidal cementite steel, which have hypereutectoid composition, was investigated by X-ray diffraction using synchrotron radiation. A detailed analysis of diffraction peak profiles reveals that the deformation behavior strongly depends on the shape of cementite in steel. The unit cell volume of the cementite in the drawn pearlitic steel compressively and elastically deforms by 1.5 to 2 pct of the initial volume at the early stage of drawing, whereas that in the drawn spheroidal cementite steel is compressed by 1 pct of the initial volume even at a large true strain. The cementite in the drawn pearlitic steel fragments into small pieces with increasing the true strain, and these pieces change to amorphous cementite. The dislocation densities of the cementite in the drawn pearlitic steel and in the drawn spheroidal cementite steel are estimated to be 1013/m2 before drawing and 1014/m2 after drawing. Although the large strain is induced in the cementite by drawing, the maximum strain energy in the cementite is too small to contribute to the dissolution of the cementite.

  14. Multitemporal InSAR analysis at Betic-Rif arc: transient and steady state ground deformation style varieties

    NASA Astrophysics Data System (ADS)

    Fernandez, J.; Gonzalez, P.

    2010-12-01

    We present results of the analysis of multitemporal Differential Synthetic Aperture Radar Interferometry (DInSAR) at the Betics-Rif arc. We exploited a collected database with more than 400 SAR images from ERS and ENVISAT satellites from 6 descending tracks in South Spain and one ascending and one descending track in Northern Morocco (Alhucemas/Al-hoceima area). We compute time series of displacements, taking care on the occurrence of significant shallow earthquakes (clear temporal discontinuities) at the phase-screen atmospheric filter step. Ground deformation velocity maps indicate a large variety in ground deformation styles from clear anthropogenic to step-wise and steady-state tectonic motions. Here, we present preliminary results of significant deformation occurring at several places along the internal zone of the arc, which guarantee discussion and foster later investigations.

  15. Properties of heterogeneous energetic materials under high strain, high strain rate deformation

    NASA Astrophysics Data System (ADS)

    Cai, Jing

    Heterogeneous energetic materials have many applications. Their dynamic behavior and microstructural evolution upon plastic deformation have remained not fully understood. The following heterogeneous materials were investigated in the this study: the pure PTFE (usually a mixture of crystalline and amorphous phases), PTFE-Sn, PTFE-Al, PTFE-Al-W, and carbon fibers filled Al alloy. Sample manufacturing processes involving ball milling and Cold Isostatic Pressing were employed. Quasi-static and Hopkinson bar tests were carried out to obtain the compressive strengths of composites. The Conventional Thick-walled Cylinder (TWC) method and newly developed small-scale Hopkinson bar based TWC experiments were conducted to investigate single shear bands and their assembly. Conventional and "soft" drop-weight tests were performed to examine the mechanical properties and the initiation of chemical reactions. Scanning Electron Microscopy was used to detect the details of the microstructures and failure mechanisms of heterogeneous materials. New features in the dynamic behavior of heterogeneous materials were observed. They include the following: (1) Strain softening, instead of thermal softening, is the main mechanism in the initiation of shear bands in explosively driven TWC tests of solid PTFE. (2) Cold isostatically pressed PTFE-Sn samples were more stable with respect to shear localization than solid PTFE. (3) The dynamic collapse of solid PTFE-Al samples with different particle sizes was accomplished with the shear localization bands and cracks. (4) Force chains in the fine W and Al particles were attributed to the high strength of the porous PTFE-Al-W composite containing fine W particles in comparison with composites with coarse W particles. (5) Debonding of metal particles from the PTFE matrix and the fracture of the matrix were identified to be two major mechanisms for the failure of the PTFE-Al-W composites. (6) The formation of PTFE nano-fibers during high strain flow

  16. Stigma, deforming metaphors and patients' moral experience of multibacillary leprosy in Sobral, Ceará State, Brazil.

    PubMed

    Nations, Marilyn K; Lira, Geison Vasconcelos; Catrib, Ana Maria Fontenelle

    2009-06-01

    In response to the call for a new Science of Stigma, this anthropological study investigates the moral experience of patients diagnosed with severe multibacillary leprosy. From 2003 to 2006, fieldwork was conducted in the so-called 'United-States-of-Sobral', in Ceará State, Northeast Brazil. Sobral is highly endemic for leprosy, despite intensified eradication efforts and a 30% increase in primary care coverage since 1999. Of 329 active leprosy cases at two public clinics, 279 multibacillary patients were identified and six information-rich cases selected for in-depth ethnographic analysis, utilizing illness narratives, key-informant interviews, home visits, participant-observation of clinical consultations and semi-structured interviews with physicians. A 'contextualized semantic interpretation' revealed four leprosy metaphors: a repulsive rat's disease, a racist skin rash, a biblical curse and lethal leukemia. Far from value-free pathology, the disease is imbued with moral significance. Patients' multivocalic illness constructions contest physicians' disease discourse. 'Skin Spot Day' discriminates more than educates. Patients' 'non-compliance' with effective multi-drug therapy is due to demoralizing stigma more than a rejection of care. 'Social leprosy' in Northeast Brazil deforms patients' moral reputations and personal dignity.

  17. High-rate Plastic Deformation of Nanocrystalline Tantalum to Large Strains: Molecular Dynamics Simulation

    SciTech Connect

    Rudd, R E

    2009-02-05

    Recent advances in the ability to generate extremes of pressure and temperature in dynamic experiments and to probe the response of materials has motivated the need for special materials optimized for those conditions as well as a need for a much deeper understanding of the behavior of materials subjected to high pressure and/or temperature. Of particular importance is the understanding of rate effects at the extremely high rates encountered in those experiments, especially with the next generation of laser drives such as at the National Ignition Facility. Here we use large-scale molecular dynamics (MD) simulations of the high-rate deformation of nanocrystalline tantalum to investigate the processes associated with plastic deformation for strains up to 100%. We use initial atomic configurations that were produced through simulations of solidification in the work of Streitz et al [Phys. Rev. Lett. 96, (2006) 225701]. These 3D polycrystalline systems have typical grain sizes of 10-20 nm. We also study a rapidly quenched liquid (amorphous solid) tantalum. We apply a constant volume (isochoric), constant temperature (isothermal) shear deformation over a range of strain rates, and compute the resulting stress-strain curves to large strains for both uniaxial and biaxial compression. We study the rate dependence and identify plastic deformation mechanisms. The identification of the mechanisms is facilitated through a novel technique that computes the local grain orientation, returning it as a quaternion for each atom. This analysis technique is robust and fast, and has been used to compute the orientations on the fly during our parallel MD simulations on supercomputers. We find both dislocation and twinning processes are important, and they interact in the weak strain hardening in these extremely fine-grained microstructures.

  18. Deformation Intermittency in Individual Crystals of a Ti 7Al Polycrystalline Ensemble Observed through High Energy X ray Diffraction Experiments (Preprint)

    DTIC Science & Technology

    2017-03-01

    work. 14. ABSTRACT (Maximum 200 words) High-energy x-ray diffraction was used to track the evolution of lattice strain in individual grains during...unlimited. Abstract High-energy x-ray diffraction was used to track the evolution of lattice strain in individual grains during creep deformation of...unlimited. triaxial stress state drives damage evolution -- is accessible with temporal resolution. Studies of kinetics are possible, and suggest the

  19. The unexpected stability of multiwall nanotubes under high pressure and shear deformation

    SciTech Connect

    Pashkin, E. Y.; Pankov, A. M.; Kulnitskiy, B. A.; Mordkovich, V. Z.; Perezhogin, I. A.; Karaeva, A. R.; Popov, M. Y.; Sorokin, P. B.; Blank, V. D.

    2016-08-22

    The behavior of multiwall carbon nanotubes under a high pressure (up to 55 GPa) combined with shear deformation was studied by experimental and theoretical methods. The unexpectedly high stability of the nanotubes' structure under high stresses was observed. After the pressure was released, we observed that the nanotubes had restored their shapes. Atomistic simulations show that the hydrostatic and shear stresses affect the nanotubes' structure in a different way. It was found that the shear stress load in the multiwall nanotubes' outer walls can induce their connection and formation of an amorphized sp{sup 3}-hybridized region but internal core keeps the tubular structure.

  20. High-quality four-dimensional cone-beam CT by deforming prior images

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Gu, Xuejun

    2013-01-01

    Due to a limited number of projections at each phase, severe view aliasing artifacts are present in four-dimensional cone beam computed tomography (4D-CBCT) when reconstruction is performed using conventional algorithms. In this work, we aim to obtain high-quality 4D-CBCT of lung cancer patients in radiation therapy by deforming the planning CT. The deformation vector fields (DVF) to deform the planning CT are estimated through matching the forward projection of the deformed prior image and measured on-treatment CBCT projection. The estimation of the DVF is formulated as an unconstrained optimization problem, where the objective function to be minimized is the sum of the squared difference between the forward projection of the deformed planning CT and the measured 4D-CBCT projection. A nonlinear conjugate gradient method is used to solve the DVF. As the number of the variables in the DVF is much greater than the number of measurements, the solution to such a highly ill-posed problem is very sensitive to the initials during the optimization process. To improve the estimation accuracy of DVF, we proposed a new strategy to obtain better initials for the optimization. In this strategy, 4D-CBCT is first reconstructed by total variation minimization. Demons deformable registration is performed to register the planning CT and the 4D-CBCT reconstructed by total variation minimization. The resulted DVF from demons registration is then used as the initial parameters in the optimization process. A 4D nonuniform rotational B-spline-based cardiac-torso (NCAT) phantom and a patient 4D-CBCT are used to evaluate the algorithm. Image quality of 4D-CBCT is substantially improved by using the proposed strategy in both NCAT phantom and patient studies. The proposed method has the potential to improve the temporal resolution of 4D-CBCT. Improved 4D-CBCT can better characterize the motion of lung tumors and will be a valuable tool for image-guided adaptive radiation therapy.

  1. High-temperature wear and deformation processes in metal matrix composites

    NASA Astrophysics Data System (ADS)

    Singh, J.; Alpas, A. T.

    1996-10-01

    Dry-sliding wear behaviors of a particulate-reinforced aluminum matrix composite 6061 Al-20 pet A12O3 and an unreinforced 6061 Al alloy were investigated in the temperature range 25 °C to 500 °C against a SAE 52100 bearing steel counterface. Experiments were carried out at a constant sliding speed of 0.2 m·s- at different test loads. The deformation behavior of the materials was studied by performing uniaxial compression tests in the same temperature range as the wear tests. Both alloys showed a mild-to-severe wear transition above a certain test temperature. In the mild wear regime, the wear rate and the coefficient of friction of the unreinforced 6061 Al decreased slightly with temperature, but the temperature had almost no effect on the wear rate and the coefficient of friction of the 6061 Al-20 pet Al2O3 in the same regime. Particulate reinforcement led to an increase in the transition temperature and a 50 to 70 pet improvement in the wear resistance in the severe wear regime. This was attributed to the formation of tribological layers consisting of comminuted A12O3 particles at the contact surface. High-temperature compression tests showed that the flow strength of 6061 Al-20 pet A12O3 and 6061 Al decreased monotonically with temperature and both alloys exhibited a work-softening behavior at temperatures higher than the inflection point on the flow stress vs temperature curves. The logarithmic maximum stress vs reciprocal temperature relationship was not linear, indicating that the deformation processes were too complicated to be characterized by a single activation energy over the whole temperature range. For the range of 250 °C to 450 °C, the activation energy for deformation was estimated to be 311 kJ·mol-1; for both the matrix alloy and the composite. Severe wear proceeded by thermally activated deformation processes involving dynamic recrystallization along a subsurface strain gradient. A power-Arrhenius type relationship was found to describe well

  2. High-quality four-dimensional cone-beam CT by deforming prior images.

    PubMed

    Wang, Jing; Gu, Xuejun

    2013-01-21

    Due to a limited number of projections at each phase, severe view aliasing artifacts are present in four-dimensional cone beam computed tomography (4D-CBCT) when reconstruction is performed using conventional algorithms. In this work, we aim to obtain high-quality 4D-CBCT of lung cancer patients in radiation therapy by deforming the planning CT. The deformation vector fields (DVF) to deform the planning CT are estimated through matching the forward projection of the deformed prior image and measured on-treatment CBCT projection. The estimation of the DVF is formulated as an unconstrained optimization problem, where the objective function to be minimized is the sum of the squared difference between the forward projection of the deformed planning CT and the measured 4D-CBCT projection. A nonlinear conjugate gradient method is used to solve the DVF. As the number of the variables in the DVF is much greater than the number of measurements, the solution to such a highly ill-posed problem is very sensitive to the initials during the optimization process. To improve the estimation accuracy of DVF, we proposed a new strategy to obtain better initials for the optimization. In this strategy, 4D-CBCT is first reconstructed by total variation minimization. Demons deformable registration is performed to register the planning CT and the 4D-CBCT reconstructed by total variation minimization. The resulted DVF from demons registration is then used as the initial parameters in the optimization process. A 4D nonuniform rotational B-spline-based cardiac-torso (NCAT) phantom and a patient 4D-CBCT are used to evaluate the algorithm. Image quality of 4D-CBCT is substantially improved by using the proposed strategy in both NCAT phantom and patient studies. The proposed method has the potential to improve the temporal resolution of 4D-CBCT. Improved 4D-CBCT can better characterize the motion of lung tumors and will be a valuable tool for image-guided adaptive radiation therapy.

  3. High-speed deformation measurement using spatially phase-shifted speckle interferometry

    NASA Astrophysics Data System (ADS)

    Beckmann, Tobias; Fratz, Markus; Bertz, Alexander; Carl, Daniel

    2014-02-01

    Electronic speckle pattern interferometry (ESPI) is a powerful technique for differential shape measurement with submicron resolution. Using spatial phase-shifting (SPS), no moving parts are required, allowing frame acquisition rates limited by camera hardware. We present ESPI images of 1 megapixel resolution at 500 fps. Analysis of SPS data involves complex, time-consuming calculations. The graphics processing units found in state-of-the-art personal computers have exceptional parallel processing capabilities, allowing real-time SPS measurements at video frame rates. Deformation analysis at this frame rate can be used to analyze transient phenomena such as transient temperature effects in integrated circuit chips or during material processing.

  4. A deformation-processed Al-matrix/Ca-nanofilamentary composite with low density, high strength, and high conductivity

    DOE PAGES

    Tian, Liang; Russell, Alan; Riedemann, Trevor; ...

    2017-03-06

    Light, strong materials with high conductivity are desired for many applications such as power transmission conductors, fly-by-wire systems, and downhole power feeds. However, it is difficult to obtain both high strength and high conductivity simultaneously in a material. In this study, an Al/Ca (20 vol%) nanofilamentary metal-metal composite was produced by powder metallurgy and severe plastic deformation. Fine Ca metal powders (~200 µm) were produced by centrifugal atomization, mixed with pure Al powder, and deformed by warm extrusion, swaging, and wire drawing to a true strain of 12.9. The Ca powder particles became fine Ca nanofilaments that reinforce the compositemore » substantially by interface strengthening. The conductivity of the composite is slightly lower than the rule-of-mixtures prediction due to minor quantities of impurity inclusions. As a result, the elevated temperature performance of this composite was also evaluated by differential scanning calorimetry and resistivity measurements.« less

  5. High-Temperature Deformation of Dry Diabase with Application to Tectonics on Venus

    NASA Technical Reports Server (NTRS)

    Mackwell, S. J.; Zimmerman, M. E.; Kohlstedt, D. L.

    1998-01-01

    We have performed an experimental study to quantify the high-temperature creep behavior of natural diabase rocks under dry deformation conditions. Samples of both Maryland diabase and Columbia diabase were investigated to measure the effects of temperature, oxygen fugacity, and plagioclase-to-pyroxene ratio on creep strength. Flow laws determined for creep of these diabases were characterized by an activation energy of Q = 485 +/- 30 kJ/mol and a stress exponent of n = 4.7 +/- 0.6, indicative of deformation dominated by dislocation creep processes. Although n and Q are the same for the two rocks within experimental error, the Maryland diabase, which has the lower plagioclase content, is significantly stronger than the Columbia diabase. Thus the modal abundance of the various minerals plays an important role in defining rock strength. Within the s ample-to-sample variation, no clear influence of oxygen fugacity on creep strength could be discerned for either rock. The dry creep strengths of both rocks are significantly greater than values previously measured on diabase under "as-received" or wet conditions. Application of these results to the present conditions in the lithosphere on Venus predicts a high viscosity crust with strong dynamic coupling between mantle convection and crustal deformation, consistent with measurements of topography and gravity for that planet.

  6. Compressive deformation behavior of CrMnFeCoNi high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Jang, Min Ji; Joo, Soo-Hyun; Tsai, Che-Wei; Yeh, Jien-Wei; Kim, Hyoung Seop

    2016-11-01

    The compressive deformation behavior of a single phase CrMnFeCoNi high-entropy alloy (HEA) is investigated using experimental and theoretical approaches. The equiaxed microstructures are observed using optical microscope, electron backscattered diffraction, and synchrotron X-ray diffraction (XRD) techniques. Compressive results reveal that the CrMnFeCoNi HEA has a high strain-hardening exponent in spite of its large grain size due to increased dislocation density and severe lattice distortion. The compressive texture of the HEA resembles those of typical FCC metals. The phenomenological dislocation-based constitutive model well describes the compressive deformation behavior. The predicted dislocation density is in good quantitative agreement with the experimental value measured using whole-profile fitting of synchrotron XRD peaks. It can be confirmed from the experimental and theoretical findings that the deformation mechanism of the CrMnFeCoNi HEA is the conventional dislocation glide and mechanical twinning is negligible contrary to general belief.

  7. Deformation behavior of SS400 Thick plate by high-frequency-induction-heating-based line heating

    NASA Astrophysics Data System (ADS)

    Lee, Kwang Seok; Eom, Deuk Ha; Lee, Jung-Hwan

    2013-03-01

    In this study, the line heating-induced permanent deformation behavior of an SS400 thick plate was investigated through both numerical analysis and experimental testing by applying high-frequency induction heating after generating dual-curvature by secondary line heating. First, an approach based on electromagnetic-thermal-structural coupling numerical analysis was adopted for predicting the temperature distribution and subsequent permanent deformation over the SS400 carbon steel plate. Experimental line heating was also carried out to validate the feasibility of the numerical analysis by applying newly designed laboratory-scale high-frequency (HF) induction-heating (IH) equipment. It was found that the shape of the heat-affected zone (HAZ) generated by HF IH and the subsequent microstructure of the SS400 carbon steel plate within the HAZ were strongly dependent on the input power. Permanent vertical deformation increased with an increase in the input power, regardless of the shape of the doubly curved plates (concave- or saddle-type plates). Transverse curvature determined in both the simulation and the experiment were investigated and compared.

  8. Extreme Adaptive Optics Testbed: High Contrast Measurements with a MEMS Deformable Mirror

    SciTech Connect

    Evans, J W; Morzinski, K; Reza, L; Severson, S; Poyneer, L; Macintosh, B; Dillon, D; Sommargren, G

    2005-08-16

    ''Extreme'' adaptive optics systems are optimized for ultra-high-contrast applications, such as ground-based extrasolar planet detection. The Extreme Adaptive Optics Testbed at UC Santa Cruz is being used to investigate and develop technologies for high-contrast imaging, especially wavefront control. We use a simple optical design to minimize wavefront error and maximize the experimentally achievable contrast. A phase shifting diffraction interferometer (PSDI) measures wavefront errors with sub-nm precision and accuracy for metrology and wavefront control. Previously, we have demonstrated RMS wavefront errors of <1.5 nm and a contrast of >10{sup 7} over a substantial region using a shaped pupil without a deformable mirror. Current work includes the installation and characterization of a 1024-actuator Micro-Electro-Mechanical-Systems (MEMS) deformable mirror, manufactured by Boston Micro-Machines for active wavefront control. Using the PSDI as the wavefront sensor we have flattened the deformable mirror to <1 nm within the controllable spatial frequencies and measured a contrast in the far field of >10{sup 6}. Consistent flattening required testing and characterization of the individual actuator response, including the effects of dead and low-response actuators. Stability and repeatability of the MEMS devices was also tested. Ultimately this testbed will be used to test all aspects of the system architecture for an extrasolar planet-finding AO system.

  9. Development of a Two-Phase Model for the Hot Deformation of Highly-Alloyed Aluminum

    SciTech Connect

    A. J. Beaudoin; J. A. Dantzig; I. M. Robertson; B. E. Gore; S. F. Harnish; H. A. Padilla

    2005-10-31

    Conventional processing methods for highly alloyed aluminum consist of ingot casting, followed by hot rolling and thermal treatments. Defects result in lost productivity and wasted energy through the need to remelt and reprocess the material. This research centers on developing a fundamental understanding for deformation of wrought 705X series alloys, a key alloy system used in structural airframe applications. The development of damage at grain boundaries is characterized through a novel test that provides initiation of failure while preserving a controlled deformation response. Data from these mechanical tests are linked to computer simulations of the hot rolling process through a critical measure of damage. Transmission electron microscopy provides fundamental insight into deformation at these high working temperatures, and--in a novel link between microscale and macroscale response--the evolution of microstructure (crystallographic orientation) provides feedback for tuning of friction in the hot rolling process. The key product of this research is a modeling framework for the analysis of industrial hot rolling.

  10. High-rate deformation and fracture of steel 09G2S

    NASA Astrophysics Data System (ADS)

    Balandin, Vl. Vas.; Balandin, Vl. Vl.; Bragov, A. M.; Igumnov, L. A.; Konstantinov, A. Yu.; Lomunov, A. K.

    2014-11-01

    The results of experimental and theoretical studies of steel 09G2S deformation and fracture laws in a wide range of strain rates and temperature variations are given. The dynamic deformation curves and the ultimate characteristics of plasticity in high-rate strain were determined by the Kolsky method in compression, extension, and shear tests. The elastoplastic properties and spall strength were studied by using the gaseous gun of calibre 57 mm and the interferometer VISAR according to the plane-wave experiment technique. The data obtained by the Kolsky method were used to determine the parameters of the Johnson-Cook model which, in the framework of the theory of flow, describes how the yield surface radius depends on the strain, strain rate, and temperature.

  11. High cell-surface density of HER2 deforms cell membranes

    PubMed Central

    Chung, Inhee; Reichelt, Mike; Shao, Lily; Akita, Robert W.; Koeppen, Hartmut; Rangell, Linda; Schaefer, Gabriele; Mellman, Ira; Sliwkowski, Mark X.

    2016-01-01

    Breast cancers (BC) with HER2 overexpression (referred to as HER2 positive) progress more aggressively than those with normal expression. Targeted therapies against HER2 can successfully delay the progression of HER2-positive BC, but details of how this overexpression drives the disease are not fully understood. Using single-molecule biophysical approaches, we discovered a new effect of HER2 overexpression on disease-relevant cell biological changes in these BC. We found HER2 overexpression causes deformation of the cell membranes, and this in turn disrupts epithelial features by perturbing cell–substrate and cell–cell contacts. This membrane deformation does not require receptor signalling activities, but results from the high levels of HER2 on the cell surface. Our finding suggests that early-stage morphological alterations of HER2-positive BC cells during cancer progression can occur in a physical and signalling-independent manner. PMID:27599456

  12. Hot Deformation Behaviors and Processing Maps of 2024 Aluminum Alloy in As-cast and Homogenized States

    NASA Astrophysics Data System (ADS)

    Chen, Liang; Zhao, Guoqun; Gong, Jie; Chen, Xiaoxue; Chen, Mengmeng

    2015-12-01

    The isothermal hot compression tests of as-cast and homogenized 2024 aluminum alloy were carried out under wide range of deformation temperatures (623-773 K) and strain rates (0.001-10 s-1). The constitutive equations for both initial states were established based on Arrhenius model, and the processing maps were constructed based on the dynamic material model. The results show that the flow stress of samples is evidently affected by both the strain rate and deformation temperature, and the flow stress in homogenized state is always higher than that in as-cast state. Through calculating the correlation coefficient ( R) and average absolute relative error of the established constitutive equations, it indicates that Arrhenius model can only provide a rough estimation on the flow stress. However, a much more precise value of the flow stress was obtained by introducing the strain compensation into Arrhenius model, since the effects of strain on the material constants were well considered. Furthermore, according to the processing maps, a suggested range of deformation temperature and strain rate for hot forming process were given then: temperature range 710-773 K and strain rate range 0.001-1 s-1 for as-cast state, and temperature range 680-773 K and strain rate range 0.003-0.22 s-1 for homogenized state.

  13. In-process deformation measurements of translucent high speed fibre-reinforced disc rotors

    NASA Astrophysics Data System (ADS)

    Philipp, Katrin; Filippatos, Angelos; Koukourakis, Nektarios; Kuschmierz, Robert; Leithold, Christoph; Langkamp, Albert; Fischer, Andreas; Czarske, Jürgen

    2015-07-01

    The high stiffness to weight ratio of glass fibre-reinforced polymers (GFRP) makes them an attractive material for rotors e.g. in the aerospace industry. We report on recent developments towards non-contact, in-situ deformation measurements with temporal resolution up to 200 µs and micron measurement uncertainty. We determine the starting point of damage evolution inside the rotor material through radial expansion measurements. This leads to a better understanding of dynamic material behaviour regarding damage evolution and the prediction of damage initiation and propagation. The measurements are conducted using a novel multi-sensor system consisting of four laser Doppler distance (LDD) sensors. The LDD sensor, a two-wavelength Mach-Zehnder interferometer was already successfully applied for dynamic deformation measurements at metallic rotors. While translucency of the GFRP rotor material limits the applicability of most optical measurement techniques due to speckles from both surface and volume of the rotor, the LDD profits from speckles and is not disturbed by backscattered laser light from the rotor volume. The LDD sensor evaluates only signals from the rotor surface. The anisotropic glass fibre-reinforcement results in a rotationally asymmetric dynamic deformation. A novel signal processing algorithm is applied for the combination of the single sensor signals to obtain the shape of the investigated rotors. In conclusion, the applied multi-sensor system allows high temporal resolution dynamic deformation measurements. First investigations regarding damage evolution inside GFRP are presented as an important step towards a fundamental understanding of the material behaviour and the prediction of damage initiation and propagation.

  14. Laboratory Studies of High Temperature Deformation and Fracture of Lava Domes

    NASA Astrophysics Data System (ADS)

    Smith, R.; Sammonds, P.; Tuffen, H.; Meredith, P.

    2007-12-01

    The high temperature fracture mechanics of magma at high temperatures exerts a fundamental control on the stability of lava domes and the timing and style of eruptions at andesitic to dacitic volcanoes. This is evidenced in the pervasive fracturing seen in both ancient and active magma conduits and lava domes; in addition to the volcanic earthquakes that occur before and during episodes of dome growth and dome collapse. Uniaxial and triaxial deformation experiments have been performed on crystal rich and crystal free magmas (andesite from Ancestral Mount Shasta, California, USA and a rhyolitic obsidian from Krafla, Iceland) at a range of temperatures (up to 900°C), confining pressures (up to 50 MPa) and strain rates (10-5s-1) to 10-3s-1) whilst recording acoustic emissions (AE). Results from these experiments provide useful inputs into models of lava dome stability, extrusion mechanisms, and source mechanisms for volcanic earthquakes. However, the large sample sizes used to ensure valid results (25mm diameter and 75mm length) made it difficult to maintain stable high temperatures under confined conditions. Also, only rudimentary AE data could be obtained, due to the distance of the transducers from the samples to keep them away from the high temperatures. Here, we present modifications to this apparatus, which include a new furnace, improved loading system, additional pore pressure and permeability measurement capability, and vastly improved acoustic monitoring. This allows (1)stable higher temperatures (up to 1000°C) to be achieved under confined conditions, (2) high temperature and moderate pressure (up to 70 MPa) hydrostatic measurements of permeability and acoustic velocities, (3) high temperature triaxial deformation under different pore fluid and pressure conditions, and (4) full waveform AE monitoring for all deformation experiments. This system can thus be used to measure the physical properties and strength of rocks under volcanic conditions and to

  15. Evolution of Fragmented Fe-Intermetallic Compounds in the Semi-Solid State of Al-Mg-Si-Fe Alloys by Deformation Semi-Solid Forming Process

    NASA Astrophysics Data System (ADS)

    Phongphisutthinan, Chakkrist; Tezuka, Hiroyasu; Kobayashi, Equo; Sato, Tatsuo

    Fe-intermetallic compounds are commonly considered as a harmful phase in the recycled aluminum alloys. The Deformation Semi-Solid Forming (D-SSF) process has advantages to modify these harmful compounds into more favorable particles by thermo-mechanical deformation and subsequently heating to the semi-solid state. The evolution of fragmented Fe-intermetallic compounds of the Al-Mg-Si-Fe alloy was investigated during heating to various semi-solid temperatures. The fragmented Fe-intermetallic compound was transformed into the polyhedral shape in the initial stage and subsequently spheroidized shape at the low semi-solid temperatures between 580-610°C. At temperatures higher than 613°C, fragmented Fe-intermetallic compounds completely melt into the liquid phase with long holding time. The Fe-intermetallic compounds are stable as solid phase at low semi-solid temperature and metastable at high semi-solid temperature.

  16. Characterization Of High-Stroke High-Aspect Ratio Micro Electro Mechanical Systems Deformable Mirrors For Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Bouchti, Mohamed Amine

    Adaptive optics MEMS deformable mirror, in conjunction with Shack Hartman wave front sensor and real-time controller, is capable of correcting time-varying aberrations in imaging applications through manipulating its mirror surface. Adaptive optics systems in astronomy for next generation large telescopes (30 meter primary mirrors) require a high stroke of 10microm of mechanical displacement. This required stroke would be achieved by MEMS deformable mirrors fabricated with high aspect ratio techniques. This thesis will review the designs of various types of high aspect actuators consisting of folded springs with rectangular and circular membranes as well as X-beam actuators. Finite element analysis (FEA) simulations of these designs have shown the ability of each design to achieve a stroke of approximately 9.4 microm. Also, FEA simulations proved that the X-beam actuators provide the best spring support while preventing tilting. In addition, this thesis will discuss device characterization and voltage vs. displacement test results for the high aspect ratio gold MEMS 16 x 16 X-beam actuators deformable mirror that has been bonded and packaged. The results have shown that the device is capable of achieving approximately 5.5 microm in individual actuator testing and 7microm in dual actuator testing.

  17. (R,p,q)-deformed quantum algebras: Coherent states and special functions

    SciTech Connect

    Hounkonnou, Mahouton Norbert; Kyemba, Joseph Desire Bukweli

    2010-06-15

    We provide with a generalization of well known (p,q)-deformed Heisenberg algebras, called (R,p,q)-deformed quantum algebras, and study the corresponding (R,p,q)-series. A general formulation of the binomial theorem is given. Special functions are obtained as limit cases. This work well prolongs a previous work by Odzijewicz [Commun. Math. Phys. 192, 183 (1998)]. Known results in the literature are recovered.

  18. The potential for achieving superplasticity in high-entropy alloys processed by severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Shahmir, Hamed; Kawasaki, Megumi; Langdon, Terence G.

    2017-05-01

    High-entropy alloys (HEAs) are now becoming important because they offer unique combinations of solid solution strengthening and good ductility at low temperatures. Only limited information is at present available on the high temperature mechanical properties of these materials. Nevertheless, it is evident that, as in conventional metallic alloys, processing through the application of severe plastic deformation can reduce the grain size to the nanometer range and this provides a potential for achieving good superplastic elongations. The superplastic data available to date are examined in this review and a comparison is made between the behaviour of HEAs and conventional superplastic alloys.

  19. Carbonates in thrust faults: High temperature investigations into deformation processes in calcite-dolomite systems

    NASA Astrophysics Data System (ADS)

    Kushnir, A.; Kennedy, L.; Misra, S.; Benson, P.

    2012-04-01

    The role of dolomite on the strength and evolution of calcite-dolomite fold and thrust belts and nappes (as observed in the Canadian Rockies, the Swiss Alps, the Italian Apennines, and the Naukluft Nappe Complex) is largely unknown. Field investigations indicate that strain in natural systems is localized in calcite, resulting in a ductile response, while dolomite deforms in a dominantly brittle manner. To date, experimental studies on polymineralic carbonate systems are limited to homogeneous, fine-grained, calcite-dolomite composites of relatively low dolomite content. The effect of dolomite on limestone rheology, the onset of crystal-plastic deformation in dolomite in composites, and the potential for strain localization in composites have not yet been fully quantified. Constant displacement rate (3x10-4 s-1and 10-4 s-1), high confining pressure (300 MPa) and high temperature (750° C and 800° C) torsion experiments were conducted to address the role of dolomite on the strength of calcite-dolomite composites. Experiments were performed on samples produced by hot isostatic pressing (HIP) amalgams of a natural, pure dolomite and a reagent, pure calcite. We performed experiments on the following mixtures (given as dolomite%): 25%, 35%, 50%, and 75%. These synthetic HIP products eliminated concerns of mineralogical impurities and textural anomalies due to porosity, structural fabrics (e.g., foliation) and fossil content. The samples were deformed up to a maximum finite shear strain of 5.0 and the experimental set up was unvented to inhibit sample decarbonation. Mechanical data shows a considerable increase in sample yield strength with increasing dolomite content. Experimental products with low starting dolomite content (dol%: 25% and 35%) display macroscopic strain localization along compositionally defined foliation. Experimental products with high dolomite content (dol%: 50% and 75%) demonstrate no macroscopic foliation. Post-deformation microstructure analysis

  20. High resolution monitoring of hydrology and deformation in a unstable slope

    NASA Astrophysics Data System (ADS)

    Nevers, Pierre; Provost, Floriane; Kromer, Ryan; Bertrand, Catherine; Malet, Jean-Philippe; Marc, Vincent; Gaillardet, Jérôme; Gance, Julien; Abellan, Antonio; Jaboyedoff, Michel

    2017-04-01

    The Séchilienne landslide is located on the right bank of the Romanche River, South East of Grenoble (Isère, France). The active zone of the gravitational instability involves several millions of cubic meters. The geology consists in fractured hard rocks (micaschists) with double permeability and strong spatial heterogeneities. The deformation of the unstable slope is monitored by on-site extensometric gauges, inclinometers, GNSS and remotely by a terrestrial radar and a total station. Hydro-chemio-mechanical processes controlling the reactivation of the landslide are influenced by the evolution of the landslide deformation in space and time, and the water circulation in the highly heterogeneous fractured media. A hydrogeochemical monitoring of the unsaturated zone in the fractured hard rock has been carried out since 2010. This monitoring is supported by the French Landslide Observatory (OMIV) and consists in continuous measurements of physico-chemical parameters on two groundwater outlets (T°C, EC, flow rate) and weekly samplings of the waters for quality monitoring. Water chemistry is a good proxy to locate in time and space the origin of the infiltrated water. This tool is used to understand the complex relationships between chemical weathering, hydromechanical changes and weakening/deformation of the unstable material. This monitoring indicates a correlation between water chemistry, rainwater infiltration and rock mass deformation highlighting the impacts of rock-water interactions on the landslide dynamics. But a distributed information over area is still needed because the heterogeneities of the slope and the few sampling points currently prevent a detailed understanding of the global mechanisms involved. To better understand and constrain the hydrogeological and hydro-chemio-mechanical behavior of the slope, a multi-method monitoring of a flood wave infiltration has been carried out in early 2016 in order to distinguish possible signals related to

  1. Modeling Anisotropic Plasticity: 3D Eulerian Hydrocode Simulations of High Strain Rate Deformation Processes

    NASA Astrophysics Data System (ADS)

    Burkett, Michael; Clancy, Sean; Maudlin, Paul; Holian, Kathleen

    2001-06-01

    : Previously developed constitutive models and solution algorithms for anisotropic elastoplastic material strength has been implemented in the three-dimensional CONEJO hydrodynamics code. CONEJO is an explicit, Eulerian continuum mechanics code that is utilized to predict formation processes associated with material deformation at elevated strain-rates and is a code development project under the Accelerated Strategic Computing Initiative (ASCI) program. Some special features of CONEJO include a high-order advection algorithm, a material interface tracking scheme, and van Leer monotonic advection-limiting. The anisotropic constitutive modeling is posed in an unrotated material frame using the theorem of polar decomposition to describe rigid body rotation. An Euler-Rodrigues description is used to quantify the rigid body rotations. Continuous quadratic yield functions fitted from polycrystal simulations for a metallic hexagonal-close-packed structure were utilized. Associative flow formulations incorporating these yield functions were solved using a geometric normal return method. Simple rectangular shear problems, "R-value" problems, and Taylor cylinder impact test data were utilized to verify and validate the implementation of the anisotropic model. A "stretching rod" problem (involving large strain and strain-rate deformation) was selected to investigate the effects of material anisotropy for this deformation process. The rod necking rate and topology was compared for CONEJO simulations using several isotropic and anisotropic descriptions that utilized the Mechanical Threshold Stress (MTS) model.

  2. Crustal deformation dynamics and stress evolution during seamount subduction: High-resolution 3-D numerical modeling

    NASA Astrophysics Data System (ADS)

    Ruh, Jonas B.; Sallarès, Valentí; Ranero, César R.; Gerya, Taras

    2016-09-01

    Seamounts or submarine volcanoes frequently collide with the overriding crust along presently active subduction zones locally modifying stress and permanent deformation patterns. Dynamics of this process is not fully understood, and several end-member scenarios of seamount-crust interaction are proposed. Here we use high-resolution 3-D numerical models to investigate evolution of crustal deformation and stress distribution within the upper plate induced by the underthrusting of subducting seamounts. The dynamical effects of the upper plate strength, subduction interface strength, and strain weakening of the crust are investigated. Experiment results demonstrate that characteristic crustal fracturing patterns formed in response to different seamount-crust interaction scenarios. Indenting seamounts strongly deform the overriding plate along a corridor as wide as the underthrusting seamount by constantly shifting subvertical shear zones rooted at the seamount extensions. A reentrant develops during initial seamount collision. A topographic bulge atop the seamount and lateral ridges emerge from further seamount subduction. Obtained stress pattern shows areas of large overpressure above the rearward and large underpressure above the trenchward flank of the seamount. Results of numerical experiments are consistent with seismic reflection images and seismic velocity models of the upper plate in areas of seamount subduction along the Middle America Trench and give important insights into the long-lasting question, whether subducting seamounts and rough seafloor act as barriers or asperities for megathrust earthquakes.

  3. Integrated experimental and computational studies of deformation of single crystal copper at high strain rates

    NASA Astrophysics Data System (ADS)

    Rawat, S.; Chandra, S.; Chavan, V. M.; Sharma, S.; Warrier, M.; Chaturvedi, S.; Patel, R. J.

    2014-12-01

    Quasi-static (0.0033 s-1) and dynamic (103 s-1) compression experiments were performed on single crystal copper along ⟨100⟩ and ⟨110⟩ directions and best-fit parameters for the Johnson-Cook (JC) material model, which is an important input to hydrodynamic simulations for shock induced fracture, have been obtained. The deformation of single crystal copper along the ⟨110⟩ direction showed high yield strength, more strain hardening, and less strain rate sensitivity as compared to the ⟨100⟩ direction. Although the JC model at the macro-scale is easy to apply and describes a general response of material deformation, it lacks physical mechanisms that describe the influence of texture and initial orientation on the material response. Hence, a crystal plasticity model based on the theory of thermally activated motion of dislocations was used at the meso-scale, in which the evolution equations permit one to study and quantify the influence of initial orientation on the material response. Hardening parameters of the crystal plasticity model show less strain rate sensitivity along the ⟨110⟩ orientation as compared to the ⟨100⟩ orientation, as also shown by the JC model. Since the deformation process is inherently multiscale in nature, the shape changes observed in the experiments due to loading along ⟨100⟩ and ⟨110⟩ directions are also validated by molecular dynamics simulations at the nano-scale.

  4. Quantifying and observing viscoplasticity at the nanoscale: highly localized deformation mechanisms in ultrathin nanocrystalline gold films.

    PubMed

    Hosseinian, Ehsan; Legros, Marc; Pierron, Olivier N

    2016-04-28

    This study unveils the stress relaxation transient deformation mechanisms in 100 nm-thick, nanocrystalline Au films thanks to a robust quantitative in situ TEM MEMS nanomechanical testing approach to quantify stress relaxation and to perform in situ observations of time-dependent deformation in ultrathin nanocrystalline films. The relaxation is characterized by a decrease in plastic strain rate of more than one order of magnitude over the first ∼30 minutes (from 10(-4) to less than 10(-5) s(-1)). For longer relaxation experiments, the plastic strain rate decreases down to 10(-7) s(-1) after several hours. The power-law exponent n, relating plastic strain rate and stress, continuously decreases from initial large values (n from 6 to 14 at t = 0) down to low values (n ∼ 1-2) after several hours. In situ TEM observations reveal that the relaxation behavior is initially accommodated by highly localized, sustained, intergranular and transgranular dislocation motion. Over time, the dislocation sources become less operative or exhausted, leading to a transition to grain-boundary-diffusion based mechanisms. The results also highlight a promising technique for nanoscale characterization of time-dependent deformation.

  5. A single-crystal model for the high-strain rate deformation of cyclotrimethylene trinitramine including phase transformations and plastic slip

    NASA Astrophysics Data System (ADS)

    Addessio, F. L.; Luscher, D. J.; Cawkwell, M. J.; Ramos, K. J.

    2017-05-01

    A continuum model for the high-rate, thermo-mechanical deformation of single-crystal cyclotrimethylene trinitramine (RDX) is developed. The model includes the effects of anisotropy, large deformations, nonlinear thermo-elasticity, phase transformations, and plastic slip. A multiplicative decomposition of the deformation gradient is used. The volumetric elastic component of the deformation is accounted for through a free-energy based equation of state for the low- (α) and high-pressure (γ) polymorphs of RDX. Crystal plasticity is addressed using a phenomenological thermal activation model. The deformation gradient for the phase transformation is based on an approach that has been applied to martensitic transformations. Simulations were conducted and compared to high-rate, impact loading of oriented RDX single crystals. The simulations considered multiple orientations of the crystal relative to the direction of shock loading and multiple sample thicknesses. Thirteen slip systems, which were inferred from indentation and x-ray topography, were used to model the α-polymorph. It is shown that by increasing the number of slip systems from the previously considered number of six (6) to thirteen (13) in the α-polymorph, better comparisons with data may be obtained. Simulations of impact conditions in the vicinity of the α- to γ-polymorph transformation (3.8 GPa) are considered. Eleven of the simulations, which were at pressures below the transformation value (3.0 GPa), were compared to experimental data. Comparison of the model was also made with available data for one experiment above the transformation pressure (4.4 GPa). Also, simulations are provided for a nominal pressure of 7.5 GPa to demonstrate the effect of the transformation kinetics on the deformation of a high-rate plate impact problem.

  6. Deformation and degradation of polymers in ultra-high-pressure liquid chromatography.

    PubMed

    Uliyanchenko, Elena; van der Wal, Sjoerd; Schoenmakers, Peter J

    2011-09-28

    Ultra-high-pressure liquid chromatography (UHPLC) using columns packed with sub-2 μm particles has great potential for separations of many types of complex samples, including polymers. However, the application of UHPLC for the analysis of polymers meets some fundamental obstacles. Small particles and narrow bore tubing in combination with high pressures generate significant shear and extensional forces in UHPLC systems, which may affect polymer chains. At high stress conditions flexible macromolecules may become extended and eventually the chemical bonds in the molecules can break. Deformation and degradation of macromolecules will affect the peak retention and the peak shape in the chromatogram, which may cause errors in the obtained results (e.g. the calculated molecular-weight distributions). In the present work we explored the limitations of UHPLC for the analysis of polymers. Degradation and deformation of macromolecules were studied by collecting and re-injecting polymer peaks and by off-line two-dimensional liquid chromatography. Polystyrene standards with molecular weight of 4 MDa and larger were found to degrade at UHPLC conditions. However, for most polymers degradation could be avoided by using low linear velocities. No degradation of 3-MDa PS (and smaller) was observed at linear velocities up to 7 mm/s. The column frits were implicated as the main sources of polymer degradation. The extent of degradation was found to depend on the type of the column and on the column history. At high flow rates degradation was observed without a column being installed. We demonstrated that polymer deformation preceded degradation. Stretched polymers eluted from the column in slalom chromatography mode (elution order opposite to that in SEC or HDC). Under certain conditions we observed co-elution of large and small PS molecules though a convolution of slalom chromatography and hydrodynamic chromatography.

  7. Mathematical and computational modeling of a ferrofluid deformable mirror for high-contrast imaging

    NASA Astrophysics Data System (ADS)

    Lemmer, Aaron J.; Griffiths, Ian M.; Groff, Tyler D.; Rousing, Andreas W.; Kasdin, N. Jeremy

    2016-07-01

    Deformable mirrors (DMs) are an enabling and mission-critical technology in any coronagraphic instrument designed to directly image exoplanets. A new ferro fluid deformable mirror technology for high-contrast imaging is currently under development at Princeton, featuring a flexible optical surface manipulated by the local electromagnetic and global hydraulic actuation of a reservoir of ferro fluid. The ferro fluid DM is designed to prioritize high optical surface quality, high-precision/low-stroke actuation, and excellent low-spatial-frequency performance - capabilities that meet the unique demands of high-contrast coronagraphy in a space-based platform. To this end, the ferro-fluid medium continuously supports the DM face sheet, a configuration that eliminates actuator print-through (or, quilting) by decoupling the nominal surface figure from the geometry of the actuator array. The global pressure control allows independent focus actuation. In this paper we describe an analytical model for the quasi-static deformation response of the DM face sheet to both magnetic and pressure actuation. These modeling efforts serve to identify the key design parameters and quantify their contributions to the DM response, model the relationship between actuation commands and DM surface-profile response, and predict performance metrics such as achievable spatial resolution and stroke precision for specific actuator configurations. Our theoretical approach addresses the complexity of the boundary conditions associated with mechanical mounting of the face sheet, and makes use of asymptotic approximations by leveraging the three distinct length scales in the problem - namely, the low-stroke ( nm) actuation, face sheet thickness ( mm), and mirror diameter (cm). In addition to describing the theoretical treatment, we report the progress of computational multi physics simulations which will be useful in improving the model fidelity and in drawing conclusions to improve the design.

  8. Constraining the equation of state of nuclear matter with gravitational wave observations: Tidal deformability and tidal disruption

    NASA Astrophysics Data System (ADS)

    Maselli, Andrea; Gualtieri, Leonardo; Ferrari, Valeria

    2013-11-01

    We study how to extract information on the neutron star equation of state from the gravitational wave signal emitted during the coalescence of a binary system composed of two neutron stars or a neutron star and a black hole. We use post-Newtonian templates which include the tidal deformability parameter and, when tidal disruption occurs before merger, a frequency cutoff. Assuming that this signal is detected by Advanced LIGO/Virgo or the Einstein Telescope, we evaluate the uncertainties on these parameters using different data-analysis strategies based on the Fisher matrix approach and on recently obtained analytical fits of the relevant quantities. We find that the tidal deformability is more effective than the stellar compactness to discriminate among different possible equations of state.

  9. Unified description of the double {beta} decay to the first quadrupole phonon state in spherical and deformed nuclei

    SciTech Connect

    Raduta, C. M.; Raduta, A. A.

    2007-10-15

    The Gamow-Teller transition operator is written as a polynomial in the dipole proton-neutron and quadrupole charge-conserving quasiparticle random-phase approximation boson operators, using the prescription of the boson expansion technique. Then, the 2{nu}{beta}{beta} process ending on the first 2{sup +} state in the daughter nucleus is allowed through one-, two-, and three-boson states describing the odd-odd intermediate nucleus. The approach uses a single particle basis that is obtained by projecting out the good angular momentum from an orthogonal set of deformed functions. The basis for mother and daughter nuclei may have different deformations. The GT transition amplitude as well as the half-lives were calculated for 18 transitions. Results are compared with the available data as well as with the predictions obtained with other methods.

  10. Active faults in the deformation zone off Noto Peninsula, Japan, revealed by high- resolution seismic profiles

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Okamura, Y.; Murakami, F.; Kimura, H.; Ikehara, K.

    2008-12-01

    Recently, a lot of earthquakes occur in Japan. The deformation zone which many faults and folds have concentrated exists on the Japan Sea side of Japan. The 2007 Noto Hanto Earthquake (MJMA 6.9) and 2007 Chuetsu-oki Earthquake (MJMA 6.8) were caused by activity of parts of faults in this deformation zone. The Noto Hanto Earthquake occurred on 25 March, 2007 under the northwestern coast of Noto Peninsula, Ishikawa Prefecture, Japan. This earthquake is located in Quaternary deformation zone that is continued from northern margin of Noto Peninsula to southeast direction (Okamura, 2007a). National Institute of Advanced Industrial Science and Technology (AIST) carried out high-resolution seismic survey using Boomer and 12 channels short streamer cable in the northern part off Noto Peninsula, in order to clarify distribution and activities of active faults in the deformation zone. A twelve channels short streamer cable with 2.5 meter channel spacing developed by AIST and private corporation is designed to get high resolution seismic profiles in shallow sea area. The multi-channel system is possible to equip on a small fishing boat, because the data acquisition system is based on PC and the length of the cable is short and easy to handle. Moreover, because the channel spacing is short, this cable is very effective for a high- resolution seismic profiling survey in the shallow sea, and seismic data obtained by multi-channel cable can be improved by velocity analysis and CDP stack. In the northern part off Noto Peninsula, seismic profiles depicting geologic structure up to 100 meters deep under sea floor were obtained. The most remarkable reflection surface recognized in the seismic profiles is erosion surface at the Last Glacial Maximum (LGM). In the western part, sediments about 30 meters (40 msec) thick cover the erosional surface that is distributed under the shelf shallower than 100m in depth and the sediments thin toward offshore and east. Flexures like deformation in

  11. Formation of Nanostructures in Severely Deformed High-Strength Steel Induced by High-Frequency Ultrasonic Impact Treatment

    NASA Astrophysics Data System (ADS)

    Dutta, R. K.; Malet, L.; Gao, H.; Hermans, M. J. M.; Godet, S.; Richardson, I. M.

    2015-02-01

    Surface modification by the generation of a nanostructured surface layer induced via ultrasonic impact treatment was performed at the weld toe of a welded high-strength quenched and tempered structural steel, S690QL1 (Fe-0.16C-0.2Si-0.87Mn-0.33Cr-0.21Mo (wt pct)). Such high-frequency peening techniques are known to improve the fatigue life of welded components. The nanocrystallized structure as a function of depth from the top-treated surface was characterized via a recently developed automated crystal orientation mapping in transmission electron microscopy. Based on the experimental observations, a grain refinement mechanism induced by plastic deformation during the ultrasonic impact treatment is proposed. It involves the formation of low-angle misoriented lamellae displaying a high density of dislocations followed by the subdivision of microbands into blocks and the resulting formation of polygonal submicronic grains. These submicronic grains further breakdown into nano grains. The results show the presence of retained austenite even after severe surface plastic deformation. The average grain size of the retained austenite and martensite is 17 and 35 nm, respectively. The in-grain deformation mechanisms are different in larger and smaller grains. Larger grains show long-range lattice rotations, while smaller grains show plastic deformation through grain rotation. Also the smaller nano grains exhibit the presence of short-range disorder. Surface nanocrystallization also leads to an increased fraction of low angle and low energy coincident site lattice boundaries especially in the smaller grains ( nm).

  12. High-temperature low-cycle fatigue behavior of a NIMONIC PE-16 superalloy—Correlation with deformation and fracture

    NASA Astrophysics Data System (ADS)

    Valsan, M.; Parameswaran, P.; Bhanu Sankara Rao, K.; Vijayalakshmi, M.; Mannan, S. L.; Shastry, D. H.

    1992-06-01

    Low-cycle fatigue (LCF) responses of NIMONIC PE-16 for various prior microstructures and strain amplitudes have been evaluated and the fatigue behavior has been explained in terms of the operative deformation mechanisms. Total strain-controlled LCF tests were performed at 923 K on samples possessing three different prior microstructures: alloy A in solution-annealed condition (free of γ' and carbides), alloy B with double aging treatment (spherical γ' of 18-nm diameter and M23C6), and alloy C with another double aging treatment (γ' of size 35 nm, MC and M23C6). All three microstructures exhibited an intial cyclic hardening followed by a period of gradual softening at 923 K. Coffin-Manson plots describing the plastic strain amplitude vs number of reversals to failure showed that alloy A had maximum fatigue life while C showed the least. Alloy B exhibited a two-slope behavior in the Coffin-Manson plot over the strain amplitudes investigated. This has been ascribed to the change in the degree of homogeneity of deformation at high and low strain amplitudes. Transmission electron microscopic studies were carried out to characterize the various deformation mechanisms and precipitation reactions occurring during fatigue testign. Fresh precipitation of fine γ' was confirmed by the development of “mottled contrast” in alloy C. Evidence for the shearing of the ordered γ' precipitates was revealed by the presence of superdislocations in alloy C. Repeated shearing during cyclic loading led to the reduction in the size of the γ' and consequent softening. Coarser γ' precipitates were associated with Orowan loops. The observed fatigue behavior has been rationalized based on the micromechanisms stated above and on the degree of homogenization of slip assessed by slipband spacing measurements on tested samples.

  13. Deformed lattice states in a Zn{sub 0.9}V{sub 0.1}Se cubic crystal

    SciTech Connect

    Maksimov, V. I. Dubinin, S. F.; Surkova, T. P.; Parkhomenko, V. D.

    2016-01-15

    Neutron scattering patterns have been recorded for a bulk Zn{sub 0.9}V{sub 0.1}Se cubic crystal at room temperature; they are indicative of macroscopic deformation in the material and its significant inhomogeneity. Specific features of the previously found state, preceding the fcc ↔ hcp structural transformation of the sphalerite lattice upon strong destabilization induced by vanadium ions in the doped ZnSe matrix, are discussed taking into account the data obtained.

  14. Deformation of Lawsonite at High Pressure and High Temperature - Implications for Low Velocity Layers in Subduction Zones

    NASA Astrophysics Data System (ADS)

    Amiguet, E.; Hilairet, N.; Wang, Y.; Gillet, P.

    2014-12-01

    During subduction, the hydrated oceanic crust undergoes a series of metamorphic reactions and transform gradually to blueschists and eclogite at depths of 20-50 km. Detailed seismic observations of subduction zones suggest a complex layered structure with the presence of a Low Velocity Layer (LVL) related to the oceanic crust [1] persisting to considerable depths (100- 250 km).While the transformation from blueschist to eclogite [2] and the presence of glaucophane up to 90-100 km [3] could explain some of these observations, the presence of LVL at greater depths could be related to the presence of the hydrous mineral lawsonite (CaAl2(Si2O7)(OH)2 H2O). Its stability field extends to 8.5 GPa and 1100K corresponding to depths up to 250 km in cold hydrous part of subducting slabs [4]. Because these regions undergo large and heterogeneous deformation, lawsonite plasticity and crystal preferred orientation (CPOs) may strongly influence the dynamic of subduction zones and the seismic properties. We present a deformation study at high presssure and high temperature on lawsonite. Six samples were deformed at 4-10 GPa and 600K to 1000K using a D-DIA apparatus [5] at 13-BMD at GSECARS beamline, APS, in axial compression up to 30% deformation with strain rates of 3.10-4s-1 to 6.10-6s-1. We measured in-situ lattice strains (a proxy for macroscopic stress), texture and strain using synchrotron radiations and calculated the macroscopic stress using lawsonite elastic properties [6]. Results from lattice strain analysis show a dependence of flow stress with temperature and strain rate. Texture analysis coupled with transmission electron microscopy showed that dislocation creep is the dominant deformation mechanism under our deformation conditions. [1] Abers, Earth and Planetary Science Letters, 176, 323-330, 2000 [2] Helffrich et al., Journal of Geophysical Research, 94, 753-763, 1989 [3] Bezacier et al., Tectonophysics, 494, 201-210, 2010 [4] Schmidt & Poli, Earth and Planetary

  15. Shear deformation of lawsonite blueschist at high pressures and implications for earthquakes in the subduction zones

    NASA Astrophysics Data System (ADS)

    Jung, Haemyeong; Choi, Seungsoon; Jung, Sejin

    2017-04-01

    Recent seismological observations indicate that many earthquakes occur at the top of subducting slabs where oceanic crust is transformed to blueschist facies rocks under high pressure and temperature conditions. Episodic slip and tremor (ETS) events and low frequency earthquakes (LFEs) and intermediate-depth earthquakes in cold subduction zones often occur where lawsonite blueschist is stable at the top of the subducting slab, but the mechanism of these earthquakes is still poorly constrained because of a lack of laboratory measurements of rock properties (i.e., lawsonite blueschist) in shear experiments at various conditions reflecting the source region of these earthquakes. Here we report the results of experimental deformation of lawsonite blueschist under high pressure and temperature conditions consistent with the stability field of lawsonite blueschist. Our data show that lawsonite blueschist deforms cataclastically at high pressures (1-2 GPa), producing faults and slip weakening through the formation of nanoparticles and amorphous phases along highly localized faults. Our results have important implications for the understanding of seismogenesis and the mechanism behind ETS/LFEs and intermediate-depth earthquakes in cold subduction zones.

  16. Study on Optimal Grouting Timing for Controlling Uplift Deformation of a Super High Arch Dam

    NASA Astrophysics Data System (ADS)

    Lin, Peng; Zhu, Xiaoxu; Li, Qingbin; Liu, Hongyuan; Yu, Yongjun

    2016-01-01

    A grouting model is developed for use during the grouting of the complex foundation of a super high arch dam. The purpose as to determine the optimal grouting timing and appropriate grouting pressure involved in controlling the uplift deformation of the dam. The model determines the optimal grouting time as the height of the arch dam increases with the concrete pouring, by checking the tensile stresses in the dam against standard specifications. The appropriate grouting pressures are given on the basis of the actual grouting pressures monitored during the upstream riverbed foundation grouting. An engineering procedure, applying the model, was then proposed and used during foundation grouting under the toe block of the Xiluodu super high-arch dam in south-western China. The quality of the foundation grouting was evaluated against the results from pressurized water permeability tests, acoustic wave velocity tests, elastic modulus tests and panoramic photographing of the rockmass on completion of the foundation grouting. The results indicated that the proposed grouting model can be applied to effectively reduce the uplift deformation and associated cracking risk for super high arch dams, and it can be concluded that the proposed engineering grouting procedure is a valuable tool for improving foundation grouting under the toe blocks of a super high arch dam.

  17. Influence of deformation on structural-phase state of weld material in St3 steel

    SciTech Connect

    Smirnov, Alexander Ababkov, Nicolay Ozhiganov, Yevgeniy; Popova, Natalya; Zboykova, Nadezhda Koneva, Nina

    2016-01-15

    The structural-phase condition of the weld material subjected to the plastic deformation was investigated using the translucent diffraction electron microscopy method. The investigations were carried out near the joint of the weld and the base metal. The seam was done by the method of manual arc welding without artificial defects. The St3 steel was taken as the welded material. Influence of the plastic deformation on morphology, phase composition, defect structure and its parameters of weld metal was revealed. All investigations were done at the distance of 0.5 mm from the joint of the weld and the base metal at the deformation degrees from 0 to 5% and after destruction of a sample. It was established that deformation of the sample did not lead to qualitative changes in the structure (the structure is still presented by ferrite-pearlite mixture) but changed the quantitative parameters of the structure, namely, with the increase of plastic deformation a part of the pearlite component becomes more and more imperfect. In the beginning it turns into the destroyed pearlite then into ferrite, the volume fraction of pearlite is decreased. The polarization of dislocation structure takes place but it doesn’t lead to the internal stresses that can destroy the sample.

  18. Influence of deformation on structural-phase state of weld material in St3 steel

    NASA Astrophysics Data System (ADS)

    Smirnov, Alexander; Kozlov, Eduard; Ababkov, Nicolay; Popova, Natalya; Nikonenko, Elena; Ozhiganov, Yevgeniy; Zboykova, Nadezhda; Koneva, Nina

    2016-01-01

    The structural-phase condition of the weld material subjected to the plastic deformation was investigated using the translucent diffraction electron microscopy method. The investigations were carried out near the joint of the weld and the base metal. The seam was done by the method of manual arc welding without artificial defects. The St3 steel was taken as the welded material. Influence of the plastic deformation on morphology, phase composition, defect structure and its parameters of weld metal was revealed. All investigations were done at the distance of 0.5 mm from the joint of the weld and the base metal at the deformation degrees from 0 to 5% and after destruction of a sample. It was established that deformation of the sample did not lead to qualitative changes in the structure (the structure is still presented by ferrite-pearlite mixture) but changed the quantitative parameters of the structure, namely, with the increase of plastic deformation a part of the pearlite component becomes more and more imperfect. In the beginning it turns into the destroyed pearlite then into ferrite, the volume fraction of pearlite is decreased. The polarization of dislocation structure takes place but it doesn't lead to the internal stresses that can destroy the sample.

  19. On plane stress state and stress free deformation of thick plate with FGM interface under thermal loading

    NASA Astrophysics Data System (ADS)

    Szubartowski, Damian; Ganczarski, Artur

    2016-10-01

    This paper demonstrates the plane stress state and the stress free thermo-elastic deformation of FGM thick plate under thermal loading. First, the Sneddon-Lockett theorem on the plane stress state in an isotropic infinite thick plate is generalized for a case of FGM problem in which all thermo-mechanical properties are optional functions of depth co-ordinate. The proof is based on application of the Iljushin thermo-elastic potential to displacement type system of equations that reduces it to the plane stress state problem. Then an existence of the purely thermal deformation is proved in two ways: first, it is shown that the unique solution fulfils conditions of simultaneous constant temperature and linear gradation of thermal expansion coefficient, second, proof is based directly on stress type system of equations which straightforwardly reduces to compatibility equations for purely thermal deformation if only stress field is homogeneous in domain and at boundary. Finally, couple examples of application to an engineering problem are presented.

  20. Engineering of surface microstructure transformations using high rate severe plastic deformation in machining

    NASA Astrophysics Data System (ADS)

    Abolghasem, Sepideh

    research effort, where Large Strain Machining (LSM) is presented as a controlled test of microstructure response. Sample conditions are created using LSM in Face Centered Cubic (FCC) metals, while characterizing the deformation using Digital Image Correlation(DIC) and Infrared(IR) thermography. Microstructural consequences such as grain size, subgrain size and grain boundary responses resulting from the characterized thermomechanical conditions are examined using Electron Back-Scattered Diffraction (EBSD). Once empirical data is generated across the broad thermomechanical conditions, reliable microstructure maps are populated. This characterization can help understand surface microstructures resulting from shear-based manufacturing processes such as turning, milling, shaping, etc. that are created under analogous thermomechanical conditions. Keywords: microstructure characterization, ultrafine grain microstructure, severe plastic deformation, high speed deformation.

  1. Stamping failure analysis of advanced high strength steel sheet based on non-uniform local deformation through thickness

    NASA Astrophysics Data System (ADS)

    Huang, Sheng; Zhao, Yixi; He, Chunfeng

    2013-12-01

    The phenomenon "Shear fracture" is often observed in the stretch-bending process of stamping over small radius with advanced high strength steels (AHSS). It occurs parallel to and near the die radius in the stretch-bending test. Since traditional Forming Limit Diagram (FLD) is unable to describe this type of failure, experimental and simulation works were constructed in this paper to investigate and predict the shear fracture. Fracture experiments were carried out through a stretch-bending test system, and failure mode was observed. There is no obviously thinning at the shear fracture surface. Further research shows that the initial crack of shear fracture occurs at the outer layer of specimen at die radius position. Finite element (FE) models were built for stretch-bending test with 3D element. The non-uniform local deformation through thickness corresponding to bending position was obtained and analyzed. Cockcroft & Latham fracture criterion is used. The outer layer of specimen at bending position reaches the critical fracture state firstly, which agrees well with experiments. Different fracture criteria are also compared and selected to determine this fracture. Results show that based on the non-uniform local deformation, the initial crack location of shear fracture at small radius can be effectively predicted by fracture criteria related to the maximum principle stress.

  2. A continuum deformation theory for metal-matrix composites at high temperature

    NASA Technical Reports Server (NTRS)

    Robinson, D. N.

    1987-01-01

    A continuum theory is presented for representing the high temperature, time dependent, hereditary deformation behavior of metallic composites that can be idealized as pseudohomogeneous continua with locally definable directional characteristics. Homogenization of textured materials (molecular, granular, fibrous) and applicability of continuum mechanics in structural applications depends on characteristic body dimensions, the severity of gradients (stress, temperature, etc.) in the structure and the relative size of the internal structure (cell size) of the material. The point of view taken here is that the composite is a material in its own right, with its own properties that can be measured and specified for the composite as a whole.

  3. Thermodynamic dislocation theory of high-temperature deformation in aluminum and steel

    NASA Astrophysics Data System (ADS)

    Le, K. C.; Tran, T. M.; Langer, J. S.

    2017-07-01

    The statistical-thermodynamic dislocation theory developed in previous papers is used here in an analysis of high-temperature deformation of aluminum and steel. Using physics-based parameters that we expect theoretically to be independent of strain rate and temperature, we are able to fit experimental stress-strain curves for three different strain rates and three different temperatures for each of these two materials. Our theoretical curves include yielding transitions at zero strain in agreement with experiment. We find that thermal softening effects are important even at the lowest temperatures and smallest strain rates.

  4. Highly Transparent Conducting Nanopaper for Solid State Foldable Electrochromic Devices.

    PubMed

    Kang, Wenbin; Lin, Meng-Fang; Chen, Jingwei; Lee, Pooi See

    2016-12-01

    It is of great challenge to develop a transparent solid state electrochromic device which is foldable at the device level. Such devices require delicate designs of every component to meet the stringent requirements for transparency, foldability, and deformation stability. Meanwhile, nanocellulose, a ubiquitous natural resource, is attracting escalating attention recently for foldable electronics due to its extreme flexibility, excellent mechanical strength, and outstanding transparency. In this article, transparent conductive nanopaper delivering the state-of-the-art electro-optical performance is achieved with a versatile nanopaper transfer method that facilitates junction fusing for high-quality electrodes. The highly compliant nanopaper electrode with excellent electrode quality, foldability, and mechanical robustness suits well for the solid state electrochromic device that maintains good performance through repeated folding, which is impossible for conventional flexible electrodes. A concept of camouflage wearables is demonstrated using gloves with embedded electrochromics. The discussed strategies here for foldable electrochromics serve as a platform technology for futuristic deformable electronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. The earthquake deformation cycle - Examples from South America and the western United States

    NASA Technical Reports Server (NTRS)

    Reilinger, Robert

    1988-01-01

    Observations of an interplate, thrust earthquake in Argentina are used to characterize a cyclic pattern of earthquake deformation. The cycle consists of steady strain accumulation, coseismic strain release, a period of continued strain release due to afterslip, and rapid postseismic strain accumulations which decrease exponentially and grade into steady strain accumulation. The cycle is used to interpret the deformation of three earthquakes in California, Alaska, and Montana, focusing on the mechanics of strain release. The results suggest that large postseismic movements can occur for strike-slip, thrust, and normal fault events. It is found that viscoelastic relaxation and postseismic afterslip should be incorporated in models of earthquake-related deformation. The use of these results for estimating earthquake repeat times from geodetic observations near active faults is considered.

  6. Study on the subgrade deformation under high-speed train loading and water-soil interaction

    NASA Astrophysics Data System (ADS)

    Han, Jian; Zhao, Guo-Tang; Sheng, Xiao-Zhen; Jin, Xue-Song

    2016-04-01

    It is important to study the subgrade characteristics of high-speed railways in consideration of the water-soil coupling dynamic problem, especially when high-speed trains operate in rainy regions. This study develops a nonlinear water-soil interaction dynamic model of slab track coupling with subgrade under high-speed train loading based on vehicle-track coupling dynamics. By using this model, the basic dynamic characteristics, including water-soil interaction and without water induced by the high-speed train loading, are studied. The main factors-the permeability coefficient and the porosity-influencing the subgrade deformation are investigated. The developed model can characterize the soil dynamic behaviour more realistically, especially when considering the influence of water-rich soil.

  7. High-precision deformation mapping in finFET transistors with two nanometre spatial resolution by precession electron diffraction.

    PubMed

    Cooper, David; Bernier, Nicolas; Rouvière, Jean-Luc; Wang, Yun-Yu; Weng, Weihao; Madan, Anita; Mochizuki, Shogo; Jagannathan, Hemanth

    2017-05-29

    Precession electron diffraction has been used to systematically measure the deformation in Si/SiGe blanket films and patterned finFET test structures grown on silicon-on-insulator type wafers. Deformation maps have been obtained with a spatial resolution of 2.0 nm and a precision of ±0.025%. The measured deformation by precession diffraction for the blanket films has been validated by comparison to energy dispersive x-ray spectrometry, X-Ray diffraction, and finite element simulations. We show that although the blanket films remain biaxially strained, the patterned fin structures are fully relaxed in the crystallographic planes that have been investigated. We demonstrate that precession diffraction is a viable deformation mapping technique that can be used to provide useful studies of state-of-the-art electronic devices.

  8. Origin and deformation of high porosity bands in the Takanoobane Rhyolite lava of Aso volcano, Japan

    NASA Astrophysics Data System (ADS)

    Furukawa, K.; Uno, K.

    2015-10-01

    In rhyolite lavas, the high porosity bands are often developed. They potentially act as pathways for gas movement to the lava surface. Since explosive activities of lavas are generally considered to be controlled by degassing system, understanding the origin and deformation process of the high porosity bands is important to assessing volcanic hazards. The Takanoobane rhyolite lava in the middle of Kyushu Island in SW Japan is effused at 51 ± 5 ka. The volume, flow length, and thickness are 0.14 km3, > 2 km, and about 90 m, respectively. The central crystalline part of the lava is characterized by the light-colored bands defined by the high porosity zone (HPZ). On the basis of geological and petrographical studies, we revealed that the HPZ was primary formed by ductile-brittle tearing of the lava (known as cavitation). According to the AMS results, the HPZs were subsequently stretched and flattened laterally during the concentric spreading of the lava. This deformation process could stretch the HPZ not only radially but also laterally. This effective stretching developed the HPZ into pervasive thin bands. Since the HPZs act as degassing pathways to the lava surface, the pervasive HPZ bands may play a role in providing volcanic gasses to void spaces created in surface fold hinges of rhyolite lavas. Thus, this degassing system may promote explosive activity of the lava surface.

  9. Recrystallization kinetics of an austenitic high-manganese steel subjected to severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Yanushkevich, Zh. Ch.; Molodov, D. A.; Belyakov, A. N.; Kaibyshev, R. O.

    2016-09-01

    The evolution of the microstructure and the properties of an austenitic high-manganese steel subjected to severe deformation by cold rolling and subsequent recrystallization annealing is investigated. Cold rolling is accompanied by mechanical structural twinning and shear banding. The microhardness and microstructural analysis of annealed samples are used to study the recrystallization kinetics of the high-manganese steel. It is shown that large plastic deformation and subsequent annealing result in rapid development of recrystallization processes and the formation of an ultrafine-grained structure. A completely recrystallized structure with an average grain size of 0.64 μm forms after 30-min annealing at a temperature of 550°C. No significant structural changes are observed when the annealing time increases to 18 h, which indicates stability of the recrystallized microstructure. The steel cold rolled to 90% and annealed at 550°C for 30 min demonstrates very high strength properties: the yield strength and the tensile strength achieve 650 and 850MPa, respectively. The dependence of the strength properties of the steel on the grain size formed after rolling and recrystallization annealing is described by the Hall-Petch relation.

  10. The mechanical microenvironment of high concentration agarose for applying deformation to primary chondrocytes.

    PubMed

    Zignego, Donald L; Jutila, Aaron A; Gelbke, Martin K; Gannon, Daniel M; June, Ronald K

    2014-06-27

    Cartilage and chondrocytes experience loading that causes alterations in chondrocyte biological activity. In vivo chondrocytes are surrounded by a pericellular matrix with a stiffness of ~25-200kPa. Understanding the mechanical loading environment of the chondrocyte is of substantial interest for understanding chondrocyte mechanotransduction. The first objective of this study was to analyze the spatial variability of applied mechanical deformations in physiologically stiff agarose on cellular and sub-cellular length scales. Fluorescent microspheres were embedded in physiologically stiff agarose hydrogels. Microsphere positions were measured via confocal microscopy and used to calculate displacement and strain fields as a function of spatial position. The second objective was to assess the feasibility of encapsulating primary human chondrocytes in physiologically stiff agarose. The third objective was to determine if primary human chondrocytes could deform in high-stiffness agarose gels. Primary human chondrocyte viability was assessed using live-dead imaging following 24 and 72h in tissue culture. Chondrocyte shape was measured before and after application of 10% compression. These data indicate that (1) displacement and strain precision are ~1% and 6.5% respectively, (2) high-stiffness agarose gels can maintain primary human chondrocyte viability of >95%, and (3) compression of chondrocytes in 4.5% agarose can induce shape changes indicative of cellular compression. Overall, these results demonstrate the feasibility of using high-concentration agarose for applying in vitro compression to chondrocytes as a model for understanding how chondrocytes respond to in vivo loading.

  11. Experimental deformation of coarse-grained rock salt to high strain

    NASA Astrophysics Data System (ADS)

    Linckens, J.; Zulauf, G.; Hammer, J.

    2016-08-01

    The processes and deformation mechanisms (e.g., dislocation creep, pressure solution, grain boundary sliding, and recrystallization) of rock salt are still a matter of debate. In order to fill this gap, high strain constriction experiments at 345°C, atmospheric pressure and a strain rate of 10-7 s-1 have been conducted on natural halite cuboids (60 × 60 × 45 mm) from the Morsleben mine of Northern Germany. Most samples were almost single crystals and contain a small amount of smaller grains (10-26%). The grain boundaries are decorated with fluid inclusions. The experiments were stopped at different final strains (ɛy = z of 10, 20, 30, and 40%) corresponding to a maximum strain (ɛx) range of 20-170%. The halite is deformed by dislocation creep, and the size of developed subgrains corresponds to the applied stress. The combined Schmid factor and subgrain boundary analysis indicate that slip was largely accommodated by the {110} < 110 > slip systems, with possible minor contribution by slip on the {100} < 110 > slip systems. Some of the deformed samples show evidence of grain boundary migration. In addition, subgrains with small misorientations form that result in large cumulative misorientations within a single grain (>40°). However, no subgrain rotation recrystallization is observed (i.e., misorientation angles are <10°). All the experiments show strain hardening, suggesting that recrystallization by grain boundary migration was not extensive and did not reset the microstructure. The experiments show that high finite strain in coarse-grained relatively dry rock salt can be accommodated by dislocation creep, without extensive dynamic recrystallization.

  12. Elastic deformation and area per lipid of membranes: atomistic view from solid-state deuterium NMR spectroscopy.

    PubMed

    Kinnun, Jacob J; Mallikarjunaiah, K J; Petrache, Horia I; Brown, Michael F

    2015-01-01

    This article reviews the application of solid-state ²H nuclear magnetic resonance (NMR) spectroscopy for investigating the deformation of lipid bilayers at the atomistic level. For liquid-crystalline membranes, the average structure is manifested by the segmental order parameters (SCD) of the lipids. Solid-state ²H NMR yields observables directly related to the stress field of the lipid bilayer. The extent to which lipid bilayers are deformed by osmotic pressure is integral to how lipid-protein interactions affect membrane functions. Calculations of the average area per lipid and related structural properties are pertinent to bilayer remodeling and molecular dynamics (MD) simulations of membranes. To establish structural quantities, such as area per lipid and volumetric bilayer thickness, a mean-torque analysis of ²H NMR order parameters is applied. Osmotic stress is introduced by adding polymer solutions or by gravimetric dehydration, which are thermodynamically equivalent. Solid-state NMR studies of lipids under osmotic stress probe membrane interactions involving collective bilayer undulations, order-director fluctuations, and lipid molecular protrusions. Removal of water yields a reduction of the mean area per lipid, with a corresponding increase in volumetric bilayer thickness, by up to 20% in the liquid-crystalline state. Hydrophobic mismatch can shift protein states involving mechanosensation, transport, and molecular recognition by G-protein-coupled receptors. Measurements of the order parameters versus osmotic pressure yield the elastic area compressibility modulus and the corresponding bilayer thickness at an atomistic level. Solid-state ²H NMR thus reveals how membrane deformation can affect protein conformational changes within the stress field of the lipid bilayer.

  13. Structural evolution during mechanical deformation in high-barrier PVDF-TFE/PET multilayer films using in situ X-ray techniques.

    PubMed

    Jordan, Alex M; Lenart, William R; Carr, Joel M; Baer, Eric; Korley, Lashanda T J

    2014-03-26

    Poly(vinylidene fluoride-co-tetrafluoroethylene) (PVDF-TFE) is confined between alternating layers of poly(ethylene terephthalate) (PET) utilizing a unique multilayer processing technology, in which PVDF-TFE and PET are melt-processed in a continuous fashion. Postprocessing techniques including biaxial orientation and melt recrystallization were used to tune the crystal orientation of the PVDF-TFE layers, as well as achieve crystallinity in the PET layers through strain-induced crystallization and thermal annealing during the melt recrystallization step. A volume additive model was used to extract the effect of crystal orientation within the PVDF-TFE layers and revealed a significant enhancement in the modulus from 730 MPa in the as-extruded state (isotropic) to 840 MPa in the biaxially oriented state (on-edge) to 2230 MPa in the melt-recrystallized state (in-plane). Subsequently, in situ wide-angle X-ray scattering was used to observe the crystal structure evolution during uniaxial deformation in both the as-extruded and melt-recrystallized states. It is observed that the low-temperature ferroelectric PVDF-TFE crystal phase in the as-extruded state exhibits equatorial sharpening of the 110 and 200 crystal peaks during deformation, quantified using the Hermans orientation function, while in the melt-recrystallized state, an overall increase in the crystallinity occurs during deformation. Thus, we correlated the mechanical response (strain hardening) of the films to these respective evolved crystal structures and highlighted the ability to tailor mechanical response. With a better understanding of the structural evolution during deformation, it is possible to more fully characterize the structural response to handling during use of the high-barrier PVDF-TFE/PET multilayer films as commercial dielectrics and packaging materials.

  14. Occurrence of oral deformities in larval anurans

    USGS Publications Warehouse

    Drake, D.L.; Altig, R.; Grace, J.B.; Walls, S.C.

    2007-01-01

    We quantified deformities in the marginal papillae, tooth rows, and jaw sheaths of tadpoles from 13 population samples representing three families and 11 sites in the southeastern United States. Oral deformities were observed in all samples and in 13.5-98% of the specimens per sample. Batrachochytrium dendrobatidis (chytrid) infections were detected in three samples. There was high variability among samples in the pattern and number of discovered deformities. Pairwise associations between oral structures containing deformities were nonrandom for several populations, especially those with B. dendrobatidis infections or high total numbers of deformities. Comparisons of deformities among samples using multivariate analyses revealed that tadpole samples grouped together by family. Analyses of ordination indicated that three variables, the number of deformities, the number of significant associations among deformity types within populations, and whether populations were infected with B. dendrobatidis, were significantly correlated with the pattern of deformities. Our data indicate that the incidence of oral deformities can be high in natural populations and that phylogeny and B. dendrobatidis infection exert a strong influence on the occurrence and type of oral deformities in tadpoles. ?? by the American Society of Ichthyologists and Herperologists.

  15. Mars' rotational state and tidal deformations from radio interferometry of a network of landers.

    NASA Astrophysics Data System (ADS)

    Iess, L.; Giuliani, S.; Dehant, V.

    2012-04-01

    The precise determination of the rotational state of solar system bodies is one of the main tools to investigate their interior structure. Unfortunately the accuracies required for geophysical interpretations are very stringent, and generally unattainable from orbit using optical or radar tracking of surface landmarks. Radio tracking of a lander from ground or from a spacecraft orbiting the planet offers substantial improvements, especially if the lander lifetime is adequately long. The optimal configuration is however attained when two or more landers can be simultaneously tracked from a ground antenna in an interferometric mode. ESA has been considering a network of landers on Mars since many years, and recently this concept has been revived by the study of the Mars Network Science Mission (MNSM). The scientific rationale of MNSM is the investigation of the Mars' interior and atmosphere by means of a network of two or three landers, making it especially suitable for interferometric observations. In order to synthesize an interferometer, the MNSN landers must be tracked simultaneously from a single ground antenna in a coherent two-way mode. The uplink radio signal (at X- or Ka-band) is received by the landers' transponders and retransmitted to ground in the same frequency band. The signals received at ground station are then recorded (typically at few tens of kHz) and beaten against each other to form the output of the interferometer, a complex phasor. The differential phase retain information on Mars' rotational parameters and tidal deformations. A crucial aspect of the interferometric configuration is the rejection of common noise and error sources. Errors in the station location, Earth orientation parameters and ephemerides, path delays due to the Earth troposphere and ionosphere, and, to a good extent, interplanetary plasma are cancelled out. The main residual errors are due to differential path delays from Mars' atmosphere and differential drifts of the

  16. In-situ neutron diffraction study of deformation behavior of a multi-component high-entropy alloy

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Liu, W. H.; Wang, X. L.; Ma, D.; Stoica, A. D.; Nieh, T. G.; He, Z. B.; Lu, Z. P.

    2014-02-01

    Deformation behavior of a high-entropy alloy (HEA) was investigated by in situ tensile deformation with neutron diffraction. It was found that the face-centered cubic (FCC) HEA alloy showed strong crystal elastic and plastic anisotropy, and the evolution of its lattice strains and textures were similar to those observed in conventional FCC metals and alloys. Our results demonstrated that, in spite of chemical complexity, the multi-component HEA behaved like a simple FCC metal and the deformation was caused by the motion of mixed dislocations.

  17. In-situ neutron diffraction study of deformation behavior of a multi-component high-entropy alloy

    SciTech Connect

    Wu, Y.; Liu, W. H.; He, Z. B.; Lu, Z. P.; Wang, X. L.; Ma, D.; Stoica, A. D.; Nieh, T. G.

    2014-02-03

    Deformation behavior of a high-entropy alloy (HEA) was investigated by in situ tensile deformation with neutron diffraction. It was found that the face-centered cubic (FCC) HEA alloy showed strong crystal elastic and plastic anisotropy, and the evolution of its lattice strains and textures were similar to those observed in conventional FCC metals and alloys. Our results demonstrated that, in spite of chemical complexity, the multi-component HEA behaved like a simple FCC metal and the deformation was caused by the motion of mixed dislocations.

  18. In situ neutron diffraction study of deformation behavior of a multi-component high-entropy alloy

    SciTech Connect

    Wu, Yuan; Liu, W H; Wang, Prof Xun-Li; Ma, Dong; Stoica, Alexandru Dan; Nieh, T. G.; He, Z b; Lu, Z.P.

    2014-01-01

    Deformation behavior of a high-entropy alloy (HEA) was investigated by in situ tensile deformation with neutron diffraction. It was found that the face-centered cubic (FCC) HEA alloy showed strong crystal elastic and plastic anisotropy, and the evolution of its lattice strains and textures were similar to those observed in conventional FCC metals and alloys. Our results demonstrated that, in spite of chemical complexity, the multi-component HEA behaved like a simple FCC metal and the deformation was caused by the motion of mixed dislocations.

  19. Four-Quasiparticle High-K States in Neutron-Deficient Lead and Polonium Nuclei

    NASA Astrophysics Data System (ADS)

    Shi, Yue; Xu, Furong

    2012-06-01

    Configuration-constrained potential energy surface calculations have been performed to investigate four-quasiparticle high-K configurations in neutron-deficient lead and polonium isotopes. A good agreement between the calculations and the experimental data has been found for the excitation energy of the observed Kπ = 19- state in 188Pb. Several lowly excited high-K states are predicted, and the large oblate deformation and low energy indicate high-K isomerism in these nuclei.

  20. Evolving Stress State and Deformation Mechanism in the Himalayan Foreland Fold-and-Thrust Belt, Northern Pakistan

    NASA Astrophysics Data System (ADS)

    Ahmad, I.; Dasti, N.

    2010-12-01

    Crustal deformation along with shortening due to northward under-thrusting of the Indian plate beneath the Eurasian plate continues to create active tectonic features on the northern fringes of the Indian craton since major collision began in the Eocene. Here the study provides insights on the evolving stress state and deformation mechanism of the Salt Range and Potwar area of Northern Pakistan. This part of Himalayan foreland fold-and-thrust-belt has severe history of deformation during 5.1 Ma and 2 Ma. This foreland area lies between Main Boundary Thrust (MBT) in the north, Himalayan Frontal Thrust (HFT) in the south and Jhelum fault of sinistral nature in the east & Kalabagh fault of dextral nature in the west. An integrated data from seismic reflection profiles and drilling logs reveal that the subsurface deformation encompasses pop-ups, imbricates, duplexes with in-sequence and out-of-sequence thrusting. It also depicts that intensity of deformation increases from the northern margin of Soan geosyncline towards north due to lacking of evaporites while in the south it decreases due to gradual increase in salt thickness. Surface geologic mapping glimpses a series of thrust sheets and anticlines trending ENE-SWS in the eastern and central part of the study area; whereas in the western part, the trend is almost E-W. This variation in the trend of structures is the result of counter clock rotational behaviour (~10°deviation from north to the west) of north-western part of the Indian lithospheric plate. Current outcrop-scale natural fracture data collected from selected anticlinal structures of the study area is presented to manifest the stress evolution and deformation styles under the established tectonic framework. Collected data is analysed for the evaluation of tectonic stress direction and deformation mechanism. The genetic arrangement and types of fractures observed in the study area indicate that the whole area is under compression. The data also testify

  1. Texture and microstructure development in Al-2%Mg during high- temperature deformation

    SciTech Connect

    Chen, S.R.; Kocks, U.F.

    1990-12-01

    The high rate sensitivity of the flow stress that is exhibited by alloys under solute drag control, such as Al-Mg at high temperatures, influences texture development because more slip systems contribute to deformation. Al-2% Mg was tested in channel-die compression, i.e. idealized rolling, at 290{degree}C and 400{degree}C, at strain rates from 10{sup {minus}1}/s to 10{sup {minus}5}/s. The texture development in rolling predicted by polycrystal plasticity simulation indicates that the brass component increases while the copper component decreases when the rate sensitivity is raised. The experimental results are in good agreement with this prediction. In addition, cube component appears when microstructural change occurs due to dynamic recrystallization. This microstructural change leads to the shift from {l angle}011{r angle} to {l angle}001{r angle} fiber texture in free compression at high temperature. 18 refs., 13 figs.

  2. Deformation and failure of OFHC copper under high strain rate shear compression

    NASA Astrophysics Data System (ADS)

    Ruggiero, Andrew; Testa, Gabriel; Bonora, Nicola; Iannitti, Gianluca; Persechino, Italo; Colliander, Magnus Hörnqvist

    2017-01-01

    Hat-shaped specimen geometries were developed to generate high strain, high-strain-rates deformation under prescribed conditions. These geometries offer also the possibility to investigate the occurrence of ductile rupture under low or negative stress triaxiality, where most failure models fail. In this work, three tophat geometries were designed, by means of extensive numerical simulation, to obtain desired stress triaxiality values within the shear region that develops across the ligament. Material failure was simulated using the Continuum Damage Model (CDM) formulation with a unilateral condition for damage accumulation and validated by comparing with quasi-static and high strain rate compression tests results on OFHC copper. Preliminary results seem to indicate that ductile tearing initiates at the specimen corner location where positive stress triaxiality occurs because of local rotation and eventually propagates along the ligament.

  3. Pinning, flow and plastic deformation of flux vortices in high T(sub c) superconductors

    NASA Technical Reports Server (NTRS)

    Roytburd, A.

    1990-01-01

    In high temperature superconductor (HTSC) materials the vortices are highly mobile and flexible. This is reflected in different models of melt of a vortex lattice. Another aspect of the problem is stressed: an easy nucleation and high mobility of dislocations in the vortex lattice. Some models of plastic deformation of vortex lattice are considered as a result of its interaction with a real crystal structure. Depinning is interpreted as yield of plastic flow is vortex medium. Effect of macroscopic defects in crystal structures (pores, inclusions, grain and domain boundaries) is being considered in detail. Available experimental facts on magnetization and a critical current in HTSC and conventional superconductors are discussed from the points of view of depinning to vortices vs. plastic flow of vortices vs. plastic flow of vortices medium.

  4. Magneto-induced large deformation and high-damping performance of a magnetorheological plastomer

    NASA Astrophysics Data System (ADS)

    Liu, Taixiang; Gong, Xinglong; Xu, Yangguang; Pang, Haoming; Xuan, Shouhu

    2014-10-01

    A magnetorheological plastomer (MRP) is a new kind of soft magneto-sensitive polymeric composite. This work reports on the large magneto-deforming effect and high magneto-damping performance of MRPs under a quasi-statical shearing condition. We demonstrate that an MRP possesses a magnetically sensitive malleability, and its magneto-mechanical behavior can be analytically described by the magneto-enhanced Bingham fluid-like model. The magneto-induced axial stress, which drives the deformation of the MRP with 70 wt % carbonyl iron powder, can be tuned in a large range from nearly 0.0 kPa to 55.4 kPa by an external 662.6 kA m-1 magnetic field. The damping performance of an MRP has a significant correlation with the magnetic strength, shear rate, carbonyl iron content and shear strain amplitude. For an MRP with 60 wt % carbonyl iron powder, the relative magneto-enhanced damping effect can reach as high as 716.2% under a quasi-statically shearing condition. Furthermore, the related physical mechanism is proposed, and we reveal that the magneto-induced, particle-assembled microstructure directs the magneto-mechanical behavior of the MRP.

  5. Stress gage system for measuring very soft materials under high rates of deformation

    NASA Astrophysics Data System (ADS)

    Kendall, Michael J.; Drodge, Daniel R.; Froud, Richard F.; Siviour, Clive R.

    2014-07-01

    Soft materials have seen continued growth in industrial importance, but are difficult to test at relevant, particularly at high, rates of deformation and relevant temperatures. This is mainly due to the low stresses supported by these materials, which mean that very sensitive force measurements are required. In this paper, a split-Hopkinson pressure bar method for testing very soft materials and elastomers at high rates of deformation is presented and applied. Experiments are conducted in compression on hydroxyl terminated polybutadiene, a very soft rubber, at strain rates of about 2000 s-1. Titanium alloy bars are used, and in addition to the usual strain gauges on the bars, forces at both ends of the specimen are measured using a piezoelectric material, lead zirconium titanate (PZT), which is much more sensitive than the quartz crystal gauges typically used in previous literature. The piezoelectric constant of PZT ranges between 290-630 × 10-12 C N-1, making it 100 times more sensitive than quartz crystal (2.3 × 10-12 C N-1). Results obtained from the experiments show that the gauges are able to measure the forces on both ends of the specimen with excellent signal to noise ratios.

  6. Highly Stretchable Superhydrophobic Composite Coating Based on Self-Adaptive Deformation of Hierarchical Structures.

    PubMed

    Hu, Xin; Tang, Changyu; He, Zhoukun; Shao, Hong; Xu, Keqin; Mei, Jun; Lau, Woon-Ming

    2017-05-01

    With the rapid development of stretchable electronics, functional textiles, and flexible sensors, water-proof protection materials are required to be built on various highly flexible substrates. However, maintaining the antiwetting of superhydrophobic surface under stretching is still a big challenge since the hierarchical structures at hybridized micro-nanoscales are easily damaged following large deformation of the substrates. This study reports a highly stretchable and mechanically stable superhydrophobic surface prepared by a facile spray coating of carbon black/polybutadiene elastomeric composite on a rubber substrate followed by thermal curing. The resulting composite coating can maintain its superhydrophobic property (water contact angle ≈170° and sliding angle <4°) at an extremely large stretching strain of up to 1000% and can withstand 1000 stretching-releasing cycles without losing its superhydrophobic property. Furthermore, the experimental observation and modeling analysis reveal that the stable superhydrophobic properties of the composite coating are attributed to the unique self-adaptive deformation ability of 3D hierarchical roughness of the composite coating, which delays the Cassie-Wenzel transition of surface wetting. In addition, it is first observed that the damaged coating can automatically recover its superhydrophobicity via a simple stretching treatment without incorporating additional hydrophobic materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Output-based mesh adaptation for high order Navier-Stokes simulations on deformable domains

    NASA Astrophysics Data System (ADS)

    Kast, Steven M.; Fidkowski, Krzysztof J.

    2013-11-01

    We present an output-based mesh adaptation strategy for Navier-Stokes simulations on deforming domains. The equations are solved with an arbitrary Lagrangian-Eulerian (ALE) approach, using a discontinuous Galerkin finite-element discretization in both space and time. Discrete unsteady adjoint solutions, derived for both the state and the geometric conservation law, provide output error estimates and drive adaptation of the space-time mesh. Spatial adaptation consists of dynamic order increment or decrement on a fixed tessellation of the domain, while a combination of coarsening and refinement is used to provide an efficient time step distribution. Results from compressible Navier-Stokes simulations in both two and three dimensions demonstrate the accuracy and efficiency of the proposed approach. In particular, the method is shown to outperform other common adaptation strategies, which, while sometimes adequate for static problems, struggle in the presence of mesh motion.

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

    PubMed

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

    2009-03-09

    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.

  9. Experimental Study of the Deformation of Synthetic White Mica Polycrystalline Aggregates at High Pressure and Temperature

    NASA Astrophysics Data System (ADS)

    Mariani, E.; Rutter, E. H.; Brodie, K. H.; Bystricky, M.; Burlini, L.

    2001-12-01

    White mica is one of the major constituents of metamorphic rocks. Phyllosilicate-bearing rocks play an important role in localizing deformation in the upper to middle crust. Most experimental studies carried out on micas have focused on understanding deformation mechanisms of dark micas and multiphase aggregates, while only a few experiments have been performed on white micas. To investigate the rheology of synthetic white mica polycrystalline aggregates (30μ m grain size), triaxial compaction and compression tests were performed at 200MPa confining pressure, up to 100MPa pore water pressure and at temperatures between 773K and 973K. Torsion experiments were carried out in a Paterson gas rig at 300MPa confining pressure and 973K. Compaction tests showed that higher temperatures and pore water pressures enhanced compaction, leading to a final porosity of < 2%. Neither static recrystallization nor breakdown reactions were observed. Samples sheared in compression between sliders at 973K and strain rates of 5x10-4s-1 and 1x10-4s-1 yielded at 60MPa and 65MPa shear stress respectively, appearing to be stronger at lower strain rates. All shear stress-shear strain curves are characterized by strain-hardening. The stress relaxation technique allowed investigation of strain rates down to 8x10-7s-1. Three experiments were performed in torsion at shear strain rate between 6.7x10-4s-1 and 6.9x10-5s-1 and shear strain γ < 7, in the absence of pore water pressure. Two samples were vented, while the third was unvented. Quasi steady state was reached for γ > 2. The unvented sample was the weakest, yielding at 30MPa shear stress. It showed strain softening before approaching steady state. Optical analysis of the microstructure shows an incipient schistosity forming at 45° to the pre-existing horizontal cleavage planes. Large recrystallized grains seem to be associated with the new schistosity.

  10. High-charge-state ion sources

    SciTech Connect

    Clark, D.J.

    1983-06-01

    Sources of high charge state positive ions have uses in a variety of research fields. For heavy ion particle accelerators higher charge state particles give greater acceleration per gap and greater bending strength in a magnet. Thus higher energies can be obtained from circular accelerators of a given size, and linear accelerators can be designed with higher energy gain per length using higher charge state ions. In atomic physics the many atomic transitions in highly charged ions supplies a wealth of spectroscopy data. High charge state ion beams are also used for charge exchange and crossed beam experiments. High charge state ion sources are reviewed. (WHK)

  11. Cyclic Deformation Behavior of Fe-18Cr-18Mn-0.63N Nickel-Free High-Nitrogen Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Shao, C. W.; Shi, F.; Li, X. W.

    2015-04-01

    Cyclic deformation and damage behavior of a Ni-free high-nitrogen austenitic stainless steel with a composition of Fe-18Cr-18Mn-0.63N (weight pct) were studied, and the internal stress and effective stress were estimated by partitioning the hysteresis loop during cyclic straining at total strain amplitudes ranging from 3.0 × 10-3 to 1.0 × 10-2. It is found that immediate cyclic softening takes place at all strain amplitudes and subsequently a saturation or quasi-saturation state develops and occupies the main part of the whole fatigue life. The internal stress increases with increasing strain amplitude, while the variation of effective stress with strain amplitude is somewhat complicated. Such a phenomenon is discussed in terms of dislocation structures and the short-range ordering caused by the interaction between nitrogen atoms and substitutional atoms. The relationship of fatigue life vs plastic strain amplitude ( N f-Δ ɛ pl/2) follows a bilinear Coffin-Manson rule, resulting from the variation in slip deformation mode with the applied strain amplitude. At the low strain amplitude, cracks initiate along slip bands, and planar slip dislocation configurations dominate the major characteristic of internal microstructures. At high strain amplitudes, intergranular (mostly along grain boundaries and few along twin boundaries) cracks are generally found, and the deformation microstructures are mainly composed of dislocation cells, stacking faults and a small amount of deformation twins, in addition to planar slip dislocation structures.

  12. High temperature and deformation field measurements at the vicinity of dynamically growing shear bands

    SciTech Connect

    Rosakis, A.J.; Ravichandran, G.; Zhou, M.

    1995-12-31

    The phenomenon of dynamic initiation and propagation of adiabatic shear bands is experimentally and numerically investigated. Pre-notched metal plates are subjected to asymmetric impact load histories (dynamic mode-II loading). Dynamic shear bands emanate from the notch tip and propagate rapidly in a direction nearly parallel to the direction of the impact. Real time temperature histories along a line intersecting and perpendicular to the shear band paths are recorded by means of a high-speed infrared detector system. The materials studied are C-300 (a maraging steel) and Ti - 6 Al - 4 V alloy. Experiments show that the peak temperatures inside the propagating shear bands are approaching 90% of the melting point for C-300 and are significantly lower for the titanium alloy (up to 600{degrees}C). Additionally, measured distances of shear band propagation indicate stronger resistance to shear banding by the Ti - 6Al - 4V alloy. Deformation fields around the propagating shear bands are recorded using high-speed photography. Shear band speeds are found to strongly depend on impact velocities, and are as high as 1200 m/s for C-300 steels. Finite Element simulations of the experiments are carried out under the context of plane strain, considering finite deformations, inertia, heat conduction, thermal softening, strain hardening and strain-rate hardening. In the simulations, the shear band propagation is assumed to be governed by a critical plastic strain criterion. The results are compared with experimental measurements obtained using the high-speed infrared detectors and high-speed photography.

  13. High-Aspect-Ratio Ridge Structures Induced by Plastic Deformation as a Novel Microfabrication Technique.

    PubMed

    Takei, Atsushi; Jin, Lihua; Fujita, Hiroyuki; Takei, A; Fujita, H; Jin, Lihua

    2016-09-14

    Wrinkles on thin film/elastomer bilayer systems provide functional surfaces. The aspect ratio of these wrinkles is critical to their functionality. Much effort has been dedicated to creating high-aspect-ratio structures on the surface of bilayer systems. A highly prestretched elastomer attached to a thin film has recently been shown to form a high-aspect-ratio structure, called a ridge structure, due to a large strain induced in the elastomer. However, the prestretch requirements of the elastomer during thin film attachment are not compatible with conventional thin film deposition methods, such as spin coating, dip coating, and chemical vapor deposition (CVD). Thus, the fabrication method is complex, and ridge structure formation is limited to planar surfaces. This paper presents a new and simple method for constructing ridge structures on a nonplanar surface using a plastic thin film/elastomer bilayer system. A plastic thin film is attached to a stress-free elastomer, and the resulting bilayer system is highly stretched one- or two-dimensionally. Upon the release of the stretch load, the deformation of the elastomer is reversible, while the plastically deformed thin film stays elongated. The combination of the length mismatch and the large strain induced in the elastomer generates ridge structures. The morphology of the plastic thin film/elastomer bilayer system is experimentally studied by varying the physical parameters, and the functionality and the applicability to a nonplanar surface are demonstrated. Finally, we simulate the effect of plasticity on morphology. This study presents a new technique for generating microscale high-aspect-ratio structures and its potential for functional surfaces.

  14. Effects of Adiabatic Heating on the High Strain Rate Deformation of Polymer Matrix Composites

    NASA Technical Reports Server (NTRS)

    Sorini, Chris; Chattopadhyay, Aditi; Goldberg, Robert K.

    2017-01-01

    Polymer matrix composites (PMCs) are increasingly being used in aerospace structures that are expected to experience complex dynamic loading conditions throughout their lifetime. As such, a detailed understanding of the high strain rate behavior of the constituents, particularly the strain rate, temperature, and pressure dependent polymer matrix, is paramount. In this paper, preliminary efforts in modeling experimentally observed temperature rises due to plastic deformation in PMCs subjected to dynamic loading are presented. To this end, an existing isothermal viscoplastic polymer constitutive formulation is extended to model adiabatic conditions by incorporating temperature dependent elastic properties and modifying the components of the inelastic strain rate tensor to explicitly depend on temperature. It is demonstrated that the modified polymer constitutive model is capable of capturing strain rate and temperature dependent yield as well as thermal softening associated with the conversion of plastic work to heat at high rates of strain. The modified constitutive model is then embedded within a strength of materials based micromechanics framework to investigate the manifestation of matrix thermal softening, due to the conversion of plastic work to heat, on the high strain rate response of a T700Epon 862 (T700E862) unidirectional composite. Adiabatic model predictions for high strain rate composite longitudinal tensile, transverse tensile, and in-plane shear loading are presented. Results show a substantial deviation from isothermal conditions; significant thermal softening is observed for matrix dominated deformation modes (transverse tension and in-plane shear), highlighting the importance of accounting for the conversion of plastic work to heat in the polymer matrix in the high strain rate analysis of PMC structures.

  15. Interplay of collective and single-particle properties of excited states of deformable odd nuclei {sup 155}Eu and {sup 161}Tm

    SciTech Connect

    Sharipov, Sh.; Ermamatov, M. J. Bayimbetova, J. K.

    2008-02-15

    The properties of excited states of two deformable odd nuclei are investigated within the nonadiabatic model previously developed by the present authors. The results of relevant calculations are compared with available experimental data.

  16. On the response of Escherichia coli to high rates of deformation

    NASA Astrophysics Data System (ADS)

    Fitzmaurice, B. C.; Painter, J. D.; Appleby-Thomas, G. J.; Wood, D. C.; Hazael, R.; McMillan, P. F.

    2017-01-01

    While a large body of work exists on the low strain-rate loading of biological systems such as bacteria, there is a paucity of information on the response of such organisms at high rates of deformation. Here, the response of a readily accessible strain of bacteria, Escherichia coli (E. coli), has been examined under shock loading conditions. Although previous studies have shown greatly reduced growth in shock conditions up to several GPa, relationships between loading conditions and bacterial response have yet to be fully elucidated. Initial results of a more rigorous investigation into the 1D shock loading response of E. coli are presented here, expectantly leading to a more comprehensive view of its behaviour when exposed to high pressures. Comparison has been drawn to provide insight into the importance of the nature of the loading regime to the survival of these biological systems.

  17. High Deformability and Particle Size Distribution of Monodisperse Phytoglycogen Nanoparticles Revealed By Atomic Force Microscopy Imaging

    NASA Astrophysics Data System (ADS)

    Baylis, Benjamin; Dutcher, John

    We have used atomic force microscopy (AFM) imaging in water to determine the volume of hydrated monodisperse phytoglycogen nanoparticles adsorbed onto mica surfaces. By significantly reducing the interaction between the AFM tip and the ``sticky'' nanoparticles, we were able to obtain high quality images. We found that the adsorbed particles are highly deformed, forming pancake-like objects on the hydrophilic mica surface. By measuring the distribution of particle volumes, we calculated the average effective spherical radius of the hydrated particles, and compared this value with that measured in solution using small angle neutron scattering. These measurements illustrate the distinct advantages of AFM imaging over other imaging techniques, namely the ability to measure the height of objects in a liquid environment.

  18. High-Resolution Seismic Imaging of Quaternary Faults and Deformation in the Los Angeles Region

    NASA Astrophysics Data System (ADS)

    Stephenson, W. J.; Odum, J. K.; Williams, R. A.; Pratt, T. L.; Dolan, J.; Shaw, J. H.

    2001-12-01

    We present results from several P-wave high-resolution seismic imaging studies in the Los Angeles region that characterize Quaternary fault activity and associated deformation. From high-resolution seismic reflection data, we seek crucial information on shallow basin geometry as well as near-surface fault geometry, displacement, slip rates, and timing of Quaternary deformation. Data acquired along a profile in Sherman Oaks reveal a geologic structure in the upper 600 m that contributed to the increased earthquake ground shaking in the high-damage areas south of and along the Los Angeles River resulting from the 1994 Northridge earthquake. A shallow sub-basin imaged on the Sherman Oaks line correlates with an area that experienced greater earthquake damage from possible geometric focussing effects. Finite-difference modeling of the imaged structural geometry along the profile suggests that a peak horizontal-velocity amplification factor of two-and-greater, as well as spatial variability, can be explained in the high-damage area by the sub-basin. High-resolution seismic reflection data acquired across the Santa Monica fault confirm the location of the fault and link related shallow strike-slip faults seen in a nearby trench to deeper structures previously observed in regional studies. The high-resolution seismic data image deformation as shallow as 15 m depth and show the Santa Monica fault dips about 30 degrees north in the upper 300 m. These data, combined with soil age estimates from the trench, yield a reverse-slip rate for the fault of about 0.5 mm/yr. The Puente Hills thrust fault is one of the major faults underlying the urban Los Angeles Basin. Industry-scale and high-resolution seismic reflection images define the location and geometry of active folds above the Puente Hills thrust fault. Four seismic profiles acquired at two locations delineate fold geometry above the thrust. At one of these sites we image an active synclinal axial surface with strata

  19. Highly compressed assembly of deformable nanogels into nanoscale suprastructures and their application in nanomedicine.

    PubMed

    Chen, Huabing; Zhu, Hongda; Hu, Jingdong; Zhao, Yanbing; Wang, Qin; Wan, Jiangling; Yang, Yajiang; Xu, Huibi; Yang, Xiangliang

    2011-04-26

    Assembly of nanoparticles as interfacial stabilizers at oil-in-water (O/W) interfaces into microscopic suprastructures for stabilizing Pickering emulsions is an intriguing focus in the fields of chemical industry and material sciences. However, it is still a major challenge to assemble nanoscale suprastructures using nanoparticles as building blocks at O/W interfaces for fabricating nanoscale emulsion droplets with applicable potential in nanomedicine. Here, we show that it is possible to fabricate the nanodroplets by assembling highly deformable nanogels into the nanoscale suprastructures at spatially confined O/W interfaces. The compressed assembly of the nanogels induced the formation of the nanoscale suprastructures upon energy input at the nanoscale O/W interface. The hydrogen bonding interaction between the nanogels at the O/W interface are possibly responsible for the stabilization of the nanoscale suprastructures. The nanoscale suprastructures are further employed to stabilize the paclitaxel-loaded nanodroplets, which are found to provide sustained release of the drug, enhanced in vitro cytotoxicity, and prolonged in vivo blood circulation. Furthermore, the tissue distribution and antitumor efficacy studies show that the nanodroplets could induce a higher drug accumulation at the tumor site and enhance tumor growth inhibition when compared with the commercial product. This approach provides a novel universal strategy to fabricate nanoscale suprastructures for stabilizing nanodroplets with built-in payloads using deformable nanoparticles and displays a promising potential in nanomedicine.

  20. Deformation of Cases in High Capacitance Value Wet Tantalum Capacitors under Environmental Stresses

    NASA Technical Reports Server (NTRS)

    Teverovsky, Alexander

    2016-01-01

    Internal gas pressure in hermetic wet tantalum capacitors is created by air, electrolyte vapor, and gas generated by electrochemical reactions at the electrodes. This pressure increases substantially with temperature and time of operation due to excessive leakage currents. Deformation of the case occurs when the internal pressure exceeds pressure of the environments and can raise significantly when a part operates in space. Contrary to the cylinder case wet tantalum capacitors that have external sealing by welding and internal sealing provided by the Teflon bushing and crimping of the case, no reliable internal sealing exists in the button case capacitors. Single seal design capacitors are used for high capacitance value wet tantalum capacitors manufactured per DLA L&M drawings #04003, 04005, and 10011, and require additional analysis to assure their reliable application in space systems. In this work, leakage currents and case deformation of button case capacitors were measured during different environmental test conditions. Recommendations for derating, screening and qualification testing are given. This work is a continuation of a series of NEPP reports related to quality and reliability of wet tantalum capacitors.

  1. A New High-Resolution Spectral Approach to Noninvasively Evaluate Wall Deformations in Arteries

    PubMed Central

    Bazan, Ivonne; Negreira, Carlos; Ramos, Antonio; Brum, Javier; Ramirez, Alfredo

    2014-01-01

    By locally measuring changes on arterial wall thickness as a function of pressure, the related Young modulus can be evaluated. This physical magnitude has shown to be an important predictive factor for cardiovascular diseases. For evaluating those changes, imaging segmentation or time correlations of ultrasonic echoes, coming from wall interfaces, are usually employed. In this paper, an alternative low-cost technique is proposed to locally evaluate variations on arterial walls, which are dynamically measured with an improved high-resolution calculation of power spectral densities in echo-traces of the wall interfaces, by using a parametric autoregressive processing. Certain wall deformations are finely detected by evaluating the echoes overtones peaks with power spectral estimations that implement Burg and Yule Walker algorithms. Results of this spectral approach are compared with a classical cross-correlation operator, in a tube phantom and “in vitro” carotid tissue. A circulating loop, mimicking heart periods and blood pressure changes, is employed to dynamically inspect each sample with a broadband ultrasonic probe, acquiring multiple A-Scans which are windowed to isolate echo-traces packets coming from distinct walls. Then the new technique and cross-correlation operator are applied to evaluate changing parietal deformations from the detection of displacements registered on the wall faces under periodic regime. PMID:24688596

  2. High-temperature deformation and failure of an orthorhombic titanium aluminide sheet material

    SciTech Connect

    Nicolaou, P.D.; Semiatin, S.L.

    1996-11-01

    The high-temperature deformation and failure behavior of an orthorhombic titanium aluminide sheet alloy (fabricated by diffusion bonding of six thin foils) was established by conducting uniaxial tension and plane-strain compression tests at 980 C and strain rates between 10{sup {minus}4} and 10{sup {minus}2} s{sup {minus}1}. The stress-strain response was characterized by a peak stress at low strains followed by moderate flow softening. Values of the strain-rate sensitivity index (m) were between 0.10 and 0.32, and the plastic anisotropy parameter (R) was of the order of 0.6 to 1.0. Cavity nucleation and growth were observed during tensile deformation at strain rates of 10{sup {minus}3} s{sup {minus}1} and higher. However, the combined effects of low m, low cavity growth rate {eta}, and flow softening were deduced to be the source of failure controlled by necking and flow localization rather than cavitation-induced fracture prior to necking.

  3. Extracellular Forces Cause the Nucleus to Deform in a Highly Controlled Anisotropic Manner

    NASA Astrophysics Data System (ADS)

    Haase, Kristina; Macadangdang, Joan K. L.; Edrington, Claire H.; Cuerrier, Charles M.; Hadjiantoniou, Sebastian; Harden, James L.; Skerjanc, Ilona S.; Pelling, Andrew E.

    2016-02-01

    Physical forces arising in the extra-cellular environment have a profound impact on cell fate and gene regulation; however the underlying biophysical mechanisms that control this sensitivity remain elusive. It is hypothesized that gene expression may be influenced by the physical deformation of the nucleus in response to force. Here, using 3T3s as a model, we demonstrate that extra-cellular forces cause cell nuclei to rapidly deform (<1 s) preferentially along their shorter nuclear axis, in an anisotropic manner. Nuclear anisotropy is shown to be regulated by the cytoskeleton within intact cells, with actin and microtubules resistant to orthonormal strains. Importantly, nuclear anisotropy is intrinsic, and observed in isolated nuclei. The sensitivity of this behaviour is influenced by chromatin organization and lamin-A expression. An anisotropic response to force was also highly conserved amongst an array of examined nuclei from differentiated and undifferentiated cell types. Although the functional purpose of this conserved material property remains elusive, it may provide a mechanism through which mechanical cues in the microenvironment are rapidly transmitted to the genome.

  4. Extracellular Forces Cause the Nucleus to Deform in a Highly Controlled Anisotropic Manner

    PubMed Central

    Haase, Kristina; Macadangdang, Joan K. L.; Edrington, Claire H.; Cuerrier, Charles M.; Hadjiantoniou, Sebastian; Harden, James L.; Skerjanc, Ilona S.; Pelling, Andrew E.

    2016-01-01

    Physical forces arising in the extra-cellular environment have a profound impact on cell fate and gene regulation; however the underlying biophysical mechanisms that control this sensitivity remain elusive. It is hypothesized that gene expression may be influenced by the physical deformation of the nucleus in response to force. Here, using 3T3s as a model, we demonstrate that extra-cellular forces cause cell nuclei to rapidly deform (<1 s) preferentially along their shorter nuclear axis, in an anisotropic manner. Nuclear anisotropy is shown to be regulated by the cytoskeleton within intact cells, with actin and microtubules resistant to orthonormal strains. Importantly, nuclear anisotropy is intrinsic, and observed in isolated nuclei. The sensitivity of this behaviour is influenced by chromatin organization and lamin-A expression. An anisotropic response to force was also highly conserved amongst an array of examined nuclei from differentiated and undifferentiated cell types. Although the functional purpose of this conserved material property remains elusive, it may provide a mechanism through which mechanical cues in the microenvironment are rapidly transmitted to the genome. PMID:26892269

  5. Coexistence of spherical states with deformed and superdeformed bands in doubly magic {sup 40}Ca: A shell-model challenge

    SciTech Connect

    Caurier, E.; Nowacki, F.

    2007-05-15

    Large-scale shell-model calculations, with dimensions reaching 10{sup 9}, are carried out to describe the recently observed deformed (ND) and superdeformed (SD) bands based on the first and second excited 0{sup +} states of {sup 40}Ca at 3.35 and 5.21 MeV, respectively. A valence space comprising two major oscillator shells, sd and pf, can accommodate most of the relevant degrees of freedom of this problem. The ND band is dominated by configurations with four particles promoted to the pf shell (4p-4h in short). The SD band by 8p-8h configurations. The ground state of {sup 40}Ca is strongly correlated, but the closed shell still amounts to 65%. The energies of the bands are very well reproduced by the calculations. The out-band transitions connecting the SD band with other states are very small and depend on the details of the mixing among the different np-nh configurations; in spite of that, the calculation describes them reasonably. For the in-band transition probabilities along the SD band, we predict a fairly constant transition quadrupole moment Q{sub 0}(t){approx}170 e fm{sup 2} up to J=10 that decreases toward the higher spins. We submit also that the J=8 states of the deformed and superdeformed bands are maximally mixed.

  6. A GPU based high-resolution multilevel biomechanical head and neck model for validating deformable image registration

    SciTech Connect

    Neylon, J. Qi, X.; Sheng, K.; Low, D. A.; Kupelian, P.; Santhanam, A.; Staton, R.; Pukala, J.; Manon, R.

    2015-01-15

    Purpose: Validating the usage of deformable image registration (DIR) for daily patient positioning is critical for adaptive radiotherapy (RT) applications pertaining to head and neck (HN) radiotherapy. The authors present a methodology for generating biomechanically realistic ground-truth data for validating DIR algorithms for HN anatomy by (a) developing a high-resolution deformable biomechanical HN model from a planning CT, (b) simulating deformations for a range of interfraction posture changes and physiological regression, and (c) generating subsequent CT images representing the deformed anatomy. Methods: The biomechanical model was developed using HN kVCT datasets and the corresponding structure contours. The voxels inside a given 3D contour boundary were clustered using a graphics processing unit (GPU) based algorithm that accounted for inconsistencies and gaps in the boundary to form a volumetric structure. While the bony anatomy was modeled as rigid body, the muscle and soft tissue structures were modeled as mass–spring-damper models with elastic material properties that corresponded to the underlying contoured anatomies. Within a given muscle structure, the voxels were classified using a uniform grid and a normalized mass was assigned to each voxel based on its Hounsfield number. The soft tissue deformation for a given skeletal actuation was performed using an implicit Euler integration with each iteration split into two substeps: one for the muscle structures and the other for the remaining soft tissues. Posture changes were simulated by articulating the skeletal structure and enabling the soft structures to deform accordingly. Physiological changes representing tumor regression were simulated by reducing the target volume and enabling the surrounding soft structures to deform accordingly. Finally, the authors also discuss a new approach to generate kVCT images representing the deformed anatomy that accounts for gaps and antialiasing artifacts that may

  7. A GPU based high-resolution multilevel biomechanical head and neck model for validating deformable image registration.

    PubMed

    Neylon, J; Qi, X; Sheng, K; Staton, R; Pukala, J; Manon, R; Low, D A; Kupelian, P; Santhanam, A

    2015-01-01

    Validating the usage of deformable image registration (dir) for daily patient positioning is critical for adaptive radiotherapy (RT) applications pertaining to head and neck (HN) radiotherapy. The authors present a methodology for generating biomechanically realistic ground-truth data for validating dir algorithms for HN anatomy by (a) developing a high-resolution deformable biomechanical HN model from a planning CT, (b) simulating deformations for a range of interfraction posture changes and physiological regression, and (c) generating subsequent CT images representing the deformed anatomy. The biomechanical model was developed using HN kVCT datasets and the corresponding structure contours. The voxels inside a given 3D contour boundary were clustered using a graphics processing unit (GPU) based algorithm that accounted for inconsistencies and gaps in the boundary to form a volumetric structure. While the bony anatomy was modeled as rigid body, the muscle and soft tissue structures were modeled as mass-spring-damper models with elastic material properties that corresponded to the underlying contoured anatomies. Within a given muscle structure, the voxels were classified using a uniform grid and a normalized mass was assigned to each voxel based on its Hounsfield number. The soft tissue deformation for a given skeletal actuation was performed using an implicit Euler integration with each iteration split into two substeps: one for the muscle structures and the other for the remaining soft tissues. Posture changes were simulated by articulating the skeletal structure and enabling the soft structures to deform accordingly. Physiological changes representing tumor regression were simulated by reducing the target volume and enabling the surrounding soft structures to deform accordingly. Finally, the authors also discuss a new approach to generate kVCT images representing the deformed anatomy that accounts for gaps and antialiasing artifacts that may be caused by the

  8. [Deformations of the vertebral column in the visually impaired schoolchildren presenting with complicated high myopia and the possibilities for its correction].

    PubMed

    Egorova, T S; Smirnova, T S; Romashin, O V; Egorova, I V

    2016-01-01

    Complicated high myopia is one of the leading causes responsible for the disablement in the children associated with visual impairment especially when it is combined with other pathological conditions and abnormalities among which are disorders of the musculoskeletal system. In the present study, we for the first time examined visually impaired schoolchildren (n=44) who suffered from high myopia complications making use of the computed optical topographer for the evaluation of the state of their vertebral column. The control group consisted of 60 children attending a secondary school. The study revealed various deformations of the musculoskeletal system including scoliosis, misalignment of the pelvis, kyphosis, hyperlordosis, torsion, platypodia, deformation of the lower extremities and the chest. These deformations were more pronounced in the visually impaired schoolchildren in comparison with the children of the same age comprising the control group (p<0,05). It is concluded that the assessment of the state of the vertebral column with the use of the apparatus yields an important information for the elaboration and application of a series of measures for the timely provision of medical assistance needed for the comprehensive rehabilitation of the visually impaired schoolchildren presenting with high myopia complications.

  9. Investigation of deformation twinning under complex stress states in a rolled magnesium alloy

    DOE PAGES

    Wu, Wei; Chuang, Chih-Pin; Qiao, Dongxiao; ...

    2016-05-15

    We employed a specially designed semi-circular notch specimen in the current study to generate the various strain conditions, including uniaxial, biaxial, shear, and plane strains, which was utilized to explore the evolution of different deformation twinning systems under complex loading conditions. We found that when using in situ synchrotron X-ray diffraction mapping method, that the extensive double twins were activated during loading, while nearly no extension twinning activity was detected. After the formation of {10.1} and {10.3} compression twins, they transformed into {10.1}-{10.2} and {10.3}-{10.2} double twins instantaneously at the early stage of deformation. The lattice strain evolutions in differentmore » hkls were mapped at selected load levels during the loading-unloading sequence. Finally, the relationship between the macroscopic straining and microscopic response was established.« less

  10. Investigation of deformation twinning under complex stress states in a rolled magnesium alloy

    SciTech Connect

    Wu, Wei; Chuang, Chih-Pin; Qiao, Dongxiao; Ren, Yang; An, Ke

    2016-05-15

    We employed a specially designed semi-circular notch specimen in the current study to generate the various strain conditions, including uniaxial, biaxial, shear, and plane strains, which was utilized to explore the evolution of different deformation twinning systems under complex loading conditions. We found that when using in situ synchrotron X-ray diffraction mapping method, that the extensive double twins were activated during loading, while nearly no extension twinning activity was detected. After the formation of {10.1} and {10.3} compression twins, they transformed into {10.1}-{10.2} and {10.3}-{10.2} double twins instantaneously at the early stage of deformation. The lattice strain evolutions in different hkls were mapped at selected load levels during the loading-unloading sequence. Finally, the relationship between the macroscopic straining and microscopic response was established.

  11. Investigation of deformation twinning under complex stress states in a rolled magnesium alloy

    SciTech Connect

    Wu, Wei; Chuang, Chih-Pin; Qiao, Dongxiao; Ren, Yang; An, Ke

    2016-05-15

    We employed a specially designed semi-circular notch specimen in the current study to generate the various strain conditions, including uniaxial, biaxial, shear, and plane strains, which was utilized to explore the evolution of different deformation twinning systems under complex loading conditions. We found that when using in situ synchrotron X-ray diffraction mapping method, that the extensive double twins were activated during loading, while nearly no extension twinning activity was detected. After the formation of {10.1} and {10.3} compression twins, they transformed into {10.1}-{10.2} and {10.3}-{10.2} double twins instantaneously at the early stage of deformation. The lattice strain evolutions in different hkls were mapped at selected load levels during the loading-unloading sequence. Finally, the relationship between the macroscopic straining and microscopic response was established.

  12. The role of nanoclay on the deformation behavior of polypropylene/maleic anhydride modified polypropylene films and fibers in full and partially molten state processing

    NASA Astrophysics Data System (ADS)

    Fujiyama-Novak, Jane Hitomi

    The behavior of polypropylene nanocomposite fibers and films under uniaxial deformation in a partial and fully molten state was investigated. A fiber that exits the die was found to contain orientation gradient in the radial direction that is preserved even after solidification without application of a take up. The shearing effect in the die results in a band of oriented outer layers in which broad surfaces of the clay particles become parallel to the surface of the fibers. The polymer phase trapped between these particles exhibit moderate to high preferential orientation levels. Conversely, in the core low levels of preferred orientation were found in both the clay and the polymer phases. Upon application of take up, the presence of clay particles substantially enhances the orientation of amorphous and crystalline phases in PP/PPgMA (maleic anhydride modified polypropylene) fibers. This is due to the substantial decrease in chain relaxation in the proximity of the clay platelets and enhancement of orientation in the polymer phase in the vicinity of particles that create amplified deformation field by their relative motions. Measurements of the clay orientation in the melt-spun fibers as they undergo "confined melting" in constrained state revealed that these naturally anisotropic nanoplatelets contribute positively to the birefringence of the fibers. A hybrid real-time spectral birefringence technique depolarized light intensity method was used to capture the mechanistic changes that take place during heating, stretching, holding and cooling cycles of PP/PPGMA and nanocomposite films in a partially molten state. During the heating stage, the birefringence and the degree of melting of the as-cast films were determined by real-time depolarizing light intensity technique. The results indicate the initial fraction of crystallites, which govern the deformation behavior of the PP films, remains in dynamic equilibrium with the molten phase prior to the deformation after

  13. Spatio-temporal modeling and optimization of a deformable-grating compressor for short high-energy laser pulses

    DOE PAGES

    Qiao, Jie; Papa, J.; Liu, X.

    2015-09-24

    Monolithic large-scale diffraction gratings are desired to improve the performance of high-energy laser systems and scale them to higher energy, but the surface deformation of these diffraction gratings induce spatio-temporal coupling that is detrimental to the focusability and compressibility of the output pulse. A new deformable-grating-based pulse compressor architecture with optimized actuator positions has been designed to correct the spatial and temporal aberrations induced by grating wavefront errors. An integrated optical model has been built to analyze the effect of grating wavefront errors on the spatio-temporal performance of a compressor based on four deformable gratings. Moreover, a 1.5-meter deformable gratingmore » has been optimized using an integrated finite-element-analysis and genetic-optimization model, leading to spatio-temporal performance similar to the baseline design with ideal gratings.« less

  14. Spatio-temporal modeling and optimization of a deformable-grating compressor for short high-energy laser pulses

    SciTech Connect

    Qiao, Jie; Papa, J.; Liu, X.

    2015-09-24

    Monolithic large-scale diffraction gratings are desired to improve the performance of high-energy laser systems and scale them to higher energy, but the surface deformation of these diffraction gratings induce spatio-temporal coupling that is detrimental to the focusability and compressibility of the output pulse. A new deformable-grating-based pulse compressor architecture with optimized actuator positions has been designed to correct the spatial and temporal aberrations induced by grating wavefront errors. An integrated optical model has been built to analyze the effect of grating wavefront errors on the spatio-temporal performance of a compressor based on four deformable gratings. Moreover, a 1.5-meter deformable grating has been optimized using an integrated finite-element-analysis and genetic-optimization model, leading to spatio-temporal performance similar to the baseline design with ideal gratings.

  15. Dynamic tensile deformation and fracture of a highly particle-filled composite using SHPB and high-speed DIC method

    NASA Astrophysics Data System (ADS)

    Zhou, Z.; Chen, P.; Guo, B.; Huang, F.

    2012-08-01

    In this work, various tensile tests, including Brazilian disc test (BDT), flattened Brazilian disc (FBD) test and semi-circular bending (SCB) test, were carried out on a highly particle-filled composite by using a split Hopkinson pressure bar (SHPB). With the consideration of low strength and low wave impedance of the materials, a quartz crystal transducer was embedded in SHPB to measure the loading forces. A high-speed camera was used to capture the deformation and fracture process of materials. Digital image correlation (DIC) method was used to process these digital images to obtain the dynamic deformation information. Based on the measured strain fields, the crack growth path was determined and the failure mechanism of samples was analyzed. Combining SHPB and DIC method, the indirect tensile stress strain plots of disc samples were obtained, and the dynamic fracture toughness of materials was measured using both FBD and SCB tests. The results show that the tensile failure strength and fracture toughness increases with the increase of strain rates, exhibiting strain rate dependence. The high-speed DIC method combined with SHPB is effective to study the dynamic tensile behaviour of brittle materials with low strengths.

  16. Control of Precambrian basement deformation zones on emplacement of the Laramide Boulder batholith and Butte mining district, Montana, United States

    USGS Publications Warehouse

    Berger, Byron R.; Hildenbrand, Thomas G.; O'Neill, J. Michael

    2011-01-01

    What are the roles of deep Precambrian basement deformation zones in the localization of subsequent shallow-crustal deformation zones and magmas? The Paleoproterozoic Great Falls tectonic zone and its included Boulder batholith (Montana, United States) provide an opportunity to examine the importance of inherited deformation fabrics in batholith emplacement and the localization of magmatic-hydrothermal mineral deposits. Northeast-trending deformation fabrics predominate in the Great Falls tectonic zone, which formed during the suturing of Paleoproterozoic and Archean cratonic masses approximately 1,800 mega-annum (Ma). Subsequent Mesoproterozoic to Neoproterozoic deformation fabrics trend northwest. Following Paleozoic through Early Cretaceous sedimentation, a Late Cretaceous fold-and-thrust belt with associated strike-slip faulting developed across the region, wherein some Proterozoic faults localized thrust faulting, while others were reactivated as strike-slip faults. The 81- to 76-Ma Boulder batholith was emplaced along the reactivated central Paleoproterozoic suture in the Great Falls tectonic zone. Early-stage Boulder batholith plutons were emplaced concurrent with east-directed thrust faulting and localized primarily by northwest-trending strike-slip and related faults. The late-stage Butte Quartz Monzonite pluton was localized in a northeast-trending pull-apart structure that formed behind the active thrust front and is axially symmetric across the underlying northeast-striking Paleoproterozoic fault zone, interpreted as a crustal suture. The modeling of potential-field geophysical data indicates that pull-apart?stage magmas fed into the structure through two funnel-shaped zones beneath the batholith. Renewed magmatic activity in the southern feeder from 66 to 64 Ma led to the formation of two small porphyry-style copper-molybdenum deposits and ensuing world-class polymetallic copper- and silver-bearing veins in the Butte mining district. Vein orientations

  17. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    NASA Astrophysics Data System (ADS)

    Huang, Xiaolong; Wang, Lijun; Deng, Jie; Jia, Shenli; Qin, Kang; Shi, Zongqian

    2016-02-01

    A high-current vacuum arc subjected to an axial magnetic field is maintained in a diffuse status. With an increase in arc current, the energy carried by the arc column to the anode becomes larger and finally leads to the anode temperature exceeding the melting point of the anode material. When the anode melting pool is formed, and the rotational plasma of the arc column delivers its momentum to the melting pool, the anode melting pool starts to rotate and also flow outwards along the radial direction, which has been photographed by some researchers using high-speed cameras. In this paper, the anode temperature and melting status is calculated using the melting and solidification model. The swirl flow of the anode melting pool and deformation of the anode is calculated using the magneto-hydrodynamic (MHD) model with the volume of fraction (VOF) method. All the models are transient 2D axial-rotational symmetric models. The influence of the impaction force of the arc plasma, electromagnetic force, viscosity force, and surface tension of the liquid metal are all considered in the model. The heat flux density injected into the anode and the arc pressure are obtained from the 3D numerical simulation of the high-current vacuum arc using the MHD model, which gives more realistic parameters for the anode simulation. Simulation results show that the depth of the anode melting pool increases with an increase in the arc current. Some droplets sputter out from the anode surface, which is caused by the inertial centrifugal force of the rotational melting pool and strong plasma pressure. Compared with the previous anode melting model without consideration of anode deformation, when the deformation and swirl flow of the anode melting pool are considered, the anode temperature is relatively lower, and just a little more than the melting point of Cu. This is because of liquid droplets sputtering out of the anode surface taking much of the energy away from the anode surface. The

  18. Small baseline subsets approach of DInSAR for investigating land surface deformation along the high-speed railway

    NASA Astrophysics Data System (ADS)

    Rao, Xiong; Tang, Yunwei

    2014-11-01

    Land surface deformation evidently exists in a newly-built high-speed railway in the southeast of China. In this study, we utilize the Small BAseline Subsets (SBAS)-Differential Synthetic Aperture Radar Interferometry (DInSAR) technique to detect land surface deformation along the railway. In this work, 40 Cosmo-SkyMed satellite images were selected to analyze the spatial distribution and velocity of the deformation in study area. 88 pairs of image with high coherence were firstly chosen with an appropriate threshold. These images were used to deduce the deformation velocity map and the variation in time series. This result can provide information for orbit correctness and ground control point (GCP) selection in the following steps. Then, more pairs of image were selected to tighten the constraint in time dimension, and to improve the final result by decreasing the phase unwrapping error. 171 combinations of SAR pairs were ultimately selected. Reliable GCPs were re-selected according to the previously derived deformation velocity map. Orbital residuals error was rectified using these GCPs, and nonlinear deformation components were estimated. Therefore, a more accurate surface deformation velocity map was produced. Precise geodetic leveling work was implemented in the meantime. We compared the leveling result with the geocoding SBAS product using the nearest neighbour method. The mean error and standard deviation of the error were respectively 0.82 mm and 4.17 mm. This result demonstrates the effectiveness of DInSAR technique for monitoring land surface deformation, which can serve as a reliable decision for supporting highspeed railway project design, construction, operation and maintenance.

  19. Internal deformation in layered Zechstein-III K-Mg salts. Structures formed by complex deformation and high contrasts in viscosity observed in drill cores.

    NASA Astrophysics Data System (ADS)

    Raith, Alexander; Urai, Janos L.

    2016-04-01

    During the evaporation of a massive salt body, alternations of interrupted and full evaporation sequences can form a complex layering of different lithologies. Viscosity contrasts of up to five orders of magnitude between these different lithologies are possible in this environment. During the late stage of an evaporation cycle potassium and magnesium (K-Mg) salts are precipitated. These K-Mg salts are of economic interest but also a known drilling hazard due to their very low viscosity. How up to 200m thick layers of these evaporites affect salt deformation at different scales is not well known. A better understanding of salt tectonics with extreme mechanical stratification is needed for better exploration and production of potassium-magnesium salts and to predict the internal structure of potential nuclear waste repositories in salt. To gain a better understanding of the internal deformation of these layers we analyzed K-Mg salt rich drill cores out of the Zechstein III-1b subunit from the Veendam Pillow 10 km southeast of Groningen, near the city Veendam in the NE Netherlands. The study area has a complex geological history with multiple tectonic phases of extension and compression forming internal deformation in the pillow but also conserving most of the original layering. Beside halite the most common minerals in the ZIII-1b are carnallite, kieserite, anhydrite and bischofite alternating in thin layers of simple composition. Seismic interpretation revealed that the internal structure of the Veendam Pillow shows areas, in which the K-Mg salt rich ZIII 1b layer is much thicker than elsewhere, as a result of salt deformation. The internal structure of the ZIII-1b on the other hand, remains unknown. The core analysis shows a strong strain concentration in the weaker Bischofite (MgCl2*6H20) and Carnallite (KMgCl3*6H20) rich layers producing tectonic breccias and highly strained layers completely overprinting the original layering. Layers formed by alternating beds

  20. Shatter cones and planar deformation features confirm Santa Marta in Piauí State, Brazil, as an impact structure

    NASA Astrophysics Data System (ADS)

    Oliveira, Grace Juliana Gonçalves; Vasconcelos, Marcos Alberto Rodrigues; Crósta, Alvaro Penteado; Reimold, Wolf Uwe; Góes, Ana Maria; Kowitz, Astrid

    2014-10-01

    A total of 184 confirmed impact structures are known on Earth to date, as registered by the Earth Impact Database. The discovery of new impact structures has progressed in recent years at a rather low rate of about two structures per year. Here, we introduce the discovery of the approximately 10 km diameter Santa Marta impact structure in Piauí State in northeastern Brazil. Santa Marta is a moderately sized complex crater structure, with a raised rim and an off-center, approximately 3.2 km wide central elevated area interpreted to coincide with the central uplift of the impact structure. The Santa Marta structure was first recognized in remote sensing imagery and, later, by distinct gravity and magnetic anomalies. Here, we provide results obtained during the first detailed ground survey. The Bouguer anomaly map shows a transition from a positive to a negative anomaly within the structure along a NE-SW trend, which may be associated with the basement signature and in parts with the signature developed after the crater was formed. Macroscopic evidence for impact in the form of shatter cones has been found in situ at the base around the central elevated plateau, and also in the interior of fractured conglomerate boulders occurring on the floor of the surrounding annular basin. Planar deformation features (PDFs) are abundant in sandstones of the central elevated plateau and at scattered locations in the inner part of the ring syncline. Together, shatter cones and PDFs provide definitive shock evidence that confirms the impact origin of Santa Marta. Crystallographic orientations of PDFs occurring in multiple sets in quartz grains are indicative of peak shock pressures of 20-25 GPa in the rocks exposed at present in the interior of the crater. In contrast to recent studies that have used additional, and sometimes highly controversial, alleged shock recognition features, Santa Marta was identified based on well-understood, traditional shock evidence.

  1. High temperature deformation mechanisms of L12-containing Co-based superalloys

    NASA Astrophysics Data System (ADS)

    Titus, Michael Shaw

    Ni-based superalloys have been used as the structural material of choice for high temperature applications in gas turbine engines since the 1940s, but their operating temperature is becoming limited by their melting temperature (Tm =1300degrees C). Despite decades of research, no viable alternatives to Ni-based superalloys have been discovered and developed. However, in 2006, a ternary gamma' phase was discovered in the Co-Al-W system that enabled a new class of Co-based superalloys to be developed. These new Co-based superalloys possess a gamma-gamma' microstructure that is nearly identical to Ni-based superalloys, which enables these superalloys to achieve extraordinary high temperature mechanical properties. Furthermore, Co-based alloys possess the added benefit of exhibiting a melting temperature of at least 100degrees C higher than commercial Ni-based superalloys. Superalloys used as the structural materials in high pressure turbine blades must withstand large thermomechanical stresses imparted from the rotating disk and hot, corrosive gases present. These stresses induce time-dependent plastic deformation, which is commonly known as creep, and new superalloys must possess adequate creep resistance over a broad range of temperature in order to be used as the structural materials for high pressure turbine blades. For these reasons, this research focuses on quantifying high temperature creep properties of new gamma'-containing Co-based superalloys and identifying the high temperature creep deformation mechanisms. The high temperature creep properties of new Co- and CoNi-based alloys were found to be comparable to Ni-based superalloys with respect to minimum creep rates and creep-rupture lives at 900degrees C up to the solvus temperature of the gamma' phase. Co-based alloys exhibited a propensity for extended superlattice stacking fault formation in the gamma' precipitates resulting from dislocation shearing events. When Ni was added to the Co-based compositions

  2. Systematics of ground-state quadrupole moments of odd-A deformed nuclei determined with muonic M x rays

    SciTech Connect

    Tanaka, Y.; Steffen, R.M.; Shera, E.B.; Reuter, W.; Hoehn, M.V.; Zumbro, J.D.

    1984-05-01

    The ground-state quadrupole moments of /sup 151/Eu, /sup 153/Eu, /sup 159/Tb, /sup 163/Dy, /sup 167/Er, /sup 177/Hf, /sup 179/Hf, /sup 191/Ir, and /sup 193/Ir were determined by measuring the quadrupole hyperfine-splitting energies of muonic M x rays. The results are Q = 0.903(10) e b for /sup 151/Eu, Q = 2.412(21) e b for /sup 153/Eu, Q = 1.432(8) e b for /sup 159/Tb, Q = 2.648(21) e b for /sup 163/Dy, Q = 3.565(29) e b for /sup 167/Er, Q = 3.365(29) e b for /sup 177/Hf, Q = 3.793(33) e b for /sup 179/Hf, Q = 0.816(9) e b for /sup 191/Ir, and Q = 0.751(9) e b for /sup 193/Ir. The present quadrupole moments, compared with values obtained from electronic-atom hyperfine measurements, show that the Sternheimer correction factors used in the rare-earth electronic-atom analysis are unreliable. Systematics of deformation parameters ..beta../sub 2/ calculated from the present quadrupole moments for odd-A nuclei, and from B(E2) values of Coulomb excitation measurements for even-A nuclei, also indicate that the largest deformation change so far known exists between /sup 151/Eu and /sup 153/Eu. Except at the onset of nuclear deformation, the deformation parameters of the odd-A nuclei are quite consistent with those of the even-A neighbors.

  3. Deformation at ambient and high temperature of in situ Laves phases-ferrite composites.

    PubMed

    Donnadieu, Patricia; Pohlmann, Carsten; Scudino, Sergio; Blandin, Jean-Jacques; Babu Surreddi, Kumar; Eckert, Jürgen

    2014-06-01

    The mechanical behavior of a Fe80Zr10Cr10 alloy has been studied at ambient and high temperature. This Fe80Zr10Cr10 alloy, whoose microstructure is formed by alternate lamellae of Laves phase and ferrite, constitutes a very simple example of an in situ CMA phase composite. The role of the Laves phase type was investigated in a previous study while the present work focuses on the influence of the microstructure length scale owing to a series of alloys cast at different cooling rates that display microstructures with Laves phase lamellae width ranging from ∼50 nm to ∼150 nm. Room temperature compression tests have revealed a very high strength (up to 2 GPa) combined with a very high ductility (up to 35%). Both strength and ductility increase with reduction of the lamella width. High temperature compression tests have shown that a high strength (900 MPa) is maintained up to 873 K. Microstructural study of the deformed samples suggests that the confinement of dislocations in the ferrite lamellae is responsible for strengthening at both ambient and high temperature. The microstructure scale in addition to CMA phase structural features stands then as a key parameter for optimization of mechanical properties of CMA in situ composites.

  4. Deformation at ambient and high temperature of in situ Laves phases-ferrite composites

    PubMed Central

    Donnadieu, Patricia; Pohlmann, Carsten; Scudino, Sergio; Blandin, Jean-Jacques; Babu Surreddi, Kumar; Eckert, Jürgen

    2014-01-01

    The mechanical behavior of a Fe80Zr10Cr10 alloy has been studied at ambient and high temperature. This Fe80Zr10Cr10 alloy, whoose microstructure is formed by alternate lamellae of Laves phase and ferrite, constitutes a very simple example of an in situ CMA phase composite. The role of the Laves phase type was investigated in a previous study while the present work focuses on the influence of the microstructure length scale owing to a series of alloys cast at different cooling rates that display microstructures with Laves phase lamellae width ranging from ∼50 nm to ∼150 nm. Room temperature compression tests have revealed a very high strength (up to 2 GPa) combined with a very high ductility (up to 35%). Both strength and ductility increase with reduction of the lamella width. High temperature compression tests have shown that a high strength (900 MPa) is maintained up to 873 K. Microstructural study of the deformed samples suggests that the confinement of dislocations in the ferrite lamellae is responsible for strengthening at both ambient and high temperature. The microstructure scale in addition to CMA phase structural features stands then as a key parameter for optimization of mechanical properties of CMA in situ composites. PMID:27877672

  5. The State High Biodiesel Project

    ERIC Educational Resources Information Center

    Heasley, Paul L.; Van Der Sluys, William G.

    2009-01-01

    Through a collaborative project in Pennsylvania, high school students developed a method for converting batches of their cafeteria's waste fryer oil into biodiesel using a 190 L (50 gal) reactor. While the biodiesel is used to supplement the school district's heating and transportation energy needs, the byproduct--glycerol--is used to make hand…

  6. The State High Biodiesel Project

    ERIC Educational Resources Information Center

    Heasley, Paul L.; Van Der Sluys, William G.

    2009-01-01

    Through a collaborative project in Pennsylvania, high school students developed a method for converting batches of their cafeteria's waste fryer oil into biodiesel using a 190 L (50 gal) reactor. While the biodiesel is used to supplement the school district's heating and transportation energy needs, the byproduct--glycerol--is used to make hand…

  7. Deformation increase of high-spin core-excited isomers in the astatine nuclei

    SciTech Connect

    Scheveneels, G.; Hardeman, F.; Neyens, G.; Coussement, R. )

    1991-06-01

    Quadrupole moments of six high-spin isomers in the At isotopes have been measured with the level-mixing-spectroscopy method: {sup 208}At(16{sup {minus}}), {sup 209}At(29/2{sup +}), {sup 210}At(19{sup +},15{sup {minus}}), {sup 211}At(39/2{sup {minus}},29/2{sup +}). The results show that level mixing spectroscopy is a promising technique to determine quadrupole moments of isomers that are difficult to measure by other in-beam hyperfine interaction methods. A large increase of the quadrupole moment is observed if neutrons are excited across or removed from the {ital N}=126 shell closure. This behavior is explained in terms of an enhanced core softness for fewer core neutrons; the aligned valence particles, moving in equatorial orbits, then easily polarize the core towards oblate deformation.

  8. FE Analysis on Shear Deformation for Asymmetrically Hot-Rolled High-Manganese Steel Strip

    NASA Astrophysics Data System (ADS)

    Sui, Feng-Li; Wang, Xin; Li, Chang-Sheng; Zhao, Jun

    2016-11-01

    Shear deformation along the longitudinal cross section of the high-manganese steel strip has been analyzed in hot asymmetrical rolling process using rigid-plastic finite element model. The friction coefficient between the rolls and the strip surfaces, the diameter of the work rolls, the speed ratio for the lower/upper rolls, the reduction rate and the initial temperature of the billet were all taken into account. Influence of these process parameters on the shear stress, the shear strain and the related shear strain energy in the center layer of the hot-rolled strip was analyzed. It is indicated that increasing the speed ratio, the reduction rate and the work roll diameter is an effective way to accumulate more shear strain energy in the strip center. A mathematical model reflecting the relationship between the shear strain energy and the process parameters has been established.

  9. An internal variable constitutive model for the large deformation of metals at high temperatures

    NASA Technical Reports Server (NTRS)

    Brown, Stuart; Anand, Lallit

    1988-01-01

    The advent of large deformation finite element methodologies is beginning to permit the numerical simulation of hot working processes whose design until recently has been based on prior industrial experience. Proper application of such finite element techniques requires realistic constitutive equations which more accurately model material behavior during hot working. A simple constitutive model for hot working is the single scalar internal variable model for isotropic thermal elastoplasticity proposed by Anand. The model is recalled and the specific scalar functions, for the equivalent plastic strain rate and the evolution equation for the internal variable, presented are slight modifications of those proposed by Anand. The modified functions are better able to represent high temperature material behavior. The monotonic constant true strain rate and strain rate jump compression experiments on a 2 percent silicon iron is briefly described. The model is implemented in the general purpose finite element program ABAQUS.

  10. Defects interaction processes in deformed high purity polycrystalline molybdenum at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Lambri, O. A.; Bonifacich, F. G.; Bozzano, P. B.; Zelada, G. I.; Plazaola, F.; García, J. A.

    2014-10-01

    Mechanical spectroscopy (damping and elastic modulus as a function of temperature) and transmission electron microscopy studies have been performed in high purity polycrystalline molybdenum plastically deformed to different values of tensile and torsion strain. Mechanical spectroscopy measurements were performed from room temperature up to 1285 K. A relaxation peak in polycrystalline molybdenum related to the movement of dislocations into lower energy configurations near grain boundaries has been discovered to appear around 1170 K. The activation energy of the peak is 4.2 eV ± 0.5 eV. This relaxation phenomenon involves the interaction between vacancies and mobile dislocations near the grain boundaries. It should be highlighted that this relaxation process is controlled by the arrangement of vacancies and dislocations which occur at temperature below 1070 K.

  11. Thermomechanical model for the plastic deformation in high power laser diodes during operation

    NASA Astrophysics Data System (ADS)

    Martín-Martín, A.; Avella, M.; Iñiguez, M. P.; Jiménez, J.; Oudart, M.; Nagle, J.

    2009-10-01

    A thermomechanical model for the mechanism of rapid degradation of AlGaAs based high power laser bars (808 nm) is presented. Thermal stresses induced in the device by local heating around a facet defect by nonradiative recombination and self-absorption of photons are calculated, as well as the conditions for the beginning of plastic deformation, when these thermal stresses overcome the yield strength. The values of the power density and of the local temperature at which the yield limit is surmounted are in agreement with the threshold values for the degradation of Al based lasers given in the literature. The present model can also elucidate the role played by the packaging stress, being able to explain how this stress reduces the optical power density threshold for failure of these lasers.

  12. High temperature deformation and fracture mechanisms in a dendritic Ni[sub 3]Al alloy

    SciTech Connect

    Kim, H.K.; Earthman, J.C. . Dept. of Mechanical and Aerospace Engineering)

    1994-03-01

    The mechanisms that control high temperature deformation and rupture were studied in a Ni[sub 3]Al alloy that was thermo-mechanically treated to produce a non-porous dendritic grain structure. Comparisons of data corresponding to the dendritic grain morphology with that for the equiaxed grain structures indicate that the dendritic morphology results in significantly lower creep rates as well as substantially greater times to rupture. Comparison of the data with numerical calculations suggests that this difference in creep strength is due to an inherent resistance to grain boundary sliding by the dendritic grain structure. A constrained cavity growth model was adapted based on microstructural observations to account for cavitation within the dendritic microstructure. The success of the model indicates that rupture time is primarily determined by constrained cavity growth on isolated dendrite boundary segments.

  13. Influence of hydrogen on deformation and fracture processes in high-strength aluminum alloys

    SciTech Connect

    Bond, G.M.; Robertson, I.M.; Birnbaum, H.K.

    1987-09-01

    Hydrogen-enhanced fracture of age hardened 7050 and 7075 alloys has been studied by an in situ environmental cell TEM deformation technique. The effects of both gaseous and solute hydrogen were investigated. The effects of high-fugacity gaseous hydrogen atmospheres on the behavior of dislocations and crack tips in these alloys were monitored by video recording of dynamic events. It is concluded that hydrogen enhances dislocation mobility and reduces the flow stress. Fracture in hydrogen was similar to that observed in vacuum except that it occurred at lower stresses due to hydrogen-enhanced dislocation mobility. Large silicon- and iron-rich precipitates influenced cracking in cathodically precharged specimens as a result of hydrogen accumulation in their vicinity.

  14. Superdeformed and highly deformed bands in 65Zn and neutron-proton interactions in Zn isotopes

    NASA Astrophysics Data System (ADS)

    Yu, C.-H.; Baktash, C.; Dobaczewski, J.; Cameron, J. A.; Devlin, M.; Eberth, J.; Galindo-Uribarri, A.; Haslip, D. S.; Lafosse, D. R.; Lampman, T. J.; Lee, I.-Y.; Lerma, F.; Macchiavelli, A. O.; Paul, S. D.; Radford, D. C.; Rudolph, D.; Sarantites, D. G.; Svensson, C. E.; Waddington, J. C.; Wilson, J. N.

    2000-10-01

    Superdeformed and highly deformed rotational bands were established in 65Zn using the 40Ca(29Si,4p)65Zn reaction, and averaged quadrupole moments were measured for two of these bands. The configurations of these bands were assigned based on Hartree-Fock calculations. One of the three bands exhibits at low ħω a rise in the J(2) dynamic moments of inertia that is similar to the alignment gain observed in 60Zn. A comparison of the rotational band configurations and their J(2) moments of inertia for light Zn isotopes suggests that the rise in J(2) is most likely caused by np interactions associated with the valence protons and neutrons occupying the g9/2 intruder orbits.

  15. Paramagnetic susceptibility of the Zr62Cu22Al10Fe5Dy1 metallic glass subjected to high-pressure torsion deformation

    NASA Astrophysics Data System (ADS)

    Korolev, A. V.; Kourov, N. I.; Pushin, V. G.; Gunderov, D. V.; Boltynjuk, E. V.; Ubyivovk, E. V.; Valiev, R. Z.

    2017-09-01

    The Zr62Cu22Al10Fe5Dy1 bulk metallic glass is studied in the as-cast state and in the state after processing by high-pressure torsion at temperatures of 20 °C and 150 °C. According to the data from X-ray diffraction and transmission electron microscopy, the structural state of the samples depends weakly on the conducted processing. At the same time, magnetic measurements reveal well recordable changes in paramagnetic susceptibility induced by the processing of the samples. It is assumed that, because of high-pressure torsion deformation, there occurs a noticeable change in the material electronic structure, which leads to a change in the full susceptibility of the samples. The performed studies demonstrate that paramagnetic susceptibility may be an indicator of a change in the structural state of paramagnetic amorphous metallic substances.

  16. High resolution 3.0 Tesla MR imaging findings in patients with bilateral Madelung's deformity.

    PubMed

    Stehling, Christoph; Langer, Martin; Nassenstein, Isabelle; Bachmann, Rainald; Heindel, Walter; Vieth, Volker

    2009-08-01

    Madelung deformity (MD) is a rare, normally painful abnormality of the wrist and forearm which characteristically begins in adolescence. Usually the deformity appears between the age of 8 and 14 years, often progressing from initially mild functional pain to fatigue and loss of strength and finally, reduced mobility. We present the MR-findings in three patients with bilateral MD, using a high-resolution imaging protocol adapted for 3.0 Tesla (3.0 T) examinations. Wrist images of three patients were acquired at a 3.0 T Scanner (Gyroscan Intera, Philips Medical Systems, Best, The Netherlands), using a dedicated phased array coil. The imaging protocol consisted of coronal T1-weighted Turbo-spin-echo (T1w-TSE) and coronal and sagittal T2-weighted TSE sequences (T2w-TSE). MR-images of these three girls demonstrated severe volar bayonet configuration of the forearms with a dorsal prominence of the ulnar head, also a curved distal radial articular surface with increased ulnar angulation, due to a deceleration of growth in the ulnar portion of the distal epiphysis. The proximal carpal row showed pyramidal configuration. Also visible was a prominent short radiolunate ligament, the so called Vickers ligament, which originates from the ulnar border of the radius, inserts into the volar pole of the lunate and likely contributes to carpal pyramidalization. Furthermore, the images demonstrated an anomalous hypertrophied and elongated volar radiotriquetral ligament which, to our knowledge, has been described elsewhere only in another case. High resolution imaging at 3.0 T permitted a detailed analysis of the complex pathomorphology in patients with MD. Investing the better signal-to-noise ratio at higher field strengths into spatial resolution an excellent image quality could be obtained, depicting the Vickers ligament and the anomalous volar radiotriquetral ligament in this rare disease.

  17. An improved approach to estimate large-gradient deformation using high resolution TerraSAR-X data

    NASA Astrophysics Data System (ADS)

    Liu, D.; Chen, R.; Riedel, B.; Niemeier, W.

    2014-09-01

    Interferometric Synthetic Aperture Radar (InSAR) has shown unique capabilities in numerous applications for deformation monitoring. However, InSAR will lose effectiveness with large-gradient deformation due to the limitation of maximum detectable phase gradient and the phase unwrapping step of InSAR. Coalfield is the exact object providing such challenges for InSAR technique. Strong mining activities often induces large scale non-linear deformation with large gradient. This paper integrates offset tracking technique based on Corner Reflector (CR) and InSAR to overcome relevant problems. By applying offset tracking to high resolution TerraSAR-X intensity images, the coarse estimation of large deformation was obtained and extracted, allowing the following InSAR processing to carry out phase unwrapping correctly. Finally, the fine estimation of deformation was done by the Persistent Scatterer InSAR (PSI) technique. The detected deformation time series indicated good root-mean-square errors (RMSE), validated by GPS in situ investigation. All InSAR data were processed in the open source software StaMPS and one in-house InSAR package.

  18. Hot deformation mechanism and microstructure evolution of an ultra-high nitrogen austenitic steel containing Nb and V

    NASA Astrophysics Data System (ADS)

    Zhang, Rong-hua; Zhou, Ze-an; Guo, Ming-wei; Qi, Jian-jun; Sun, Shu-hua; Fu, Wan-tang

    2015-10-01

    The flow curves of an ultra-high nitrogen austenitic steel containing niobium (Nb) and vanadium (V) were obtained by hot compression deformation at temperatures ranging from 1000°C to 1200°C and strain rates ranging from 0.001 s-1 to 10 s-1. The mechanical behavior during hot deformation was discussed on the basis of flow curves and hot processing maps. The microstructures were analyzed via scanning electron microscopy and electron backscatter diffraction. The relationship between deformation conditions and grain size after dynamic recrystallization was obtained. The results show that the flow stress and peak strain both increase with decreasing temperature and increasing strain rate. The hot deformation activation energy is approximately 631 kJ/mol, and a hot deformation equation is proposed. (Nb,V)N precipitates with either round, square, or irregular shapes are observed at the grain boundaries and in the matrix after deformation. According to the discussion, the hot working should be processed in the temperature range of 1050°C to 1150°C and in the strain rate range of 0.01 to 1 s-1.

  19. Millimetre wave spectroscopy of high Rydberg states

    NASA Astrophysics Data System (ADS)

    Merkt, F.; Osterwalder, A.

    We have recently developed high-resolution vacuum ultraviolet laser sources and combined these with millimetre waves in double-resonance experiments to achieve a spectral resolution of up to 60 kHz in the spectra of high Rydberg states. The article describes the main features of our experimental procedure and presents studies in which we have used millimetre wave spectroscopy (a) to obtain information on the energy level structure, including the spin-orbit and hyperfine structure, of atomic Rydberg states at high principal quantum numbers n , (b) to record spectrally resolved spectra of the high Rydberg states ( n ≥100) detected in pulsed-field-ionization zero-kinetic-energy photoelectron spectra, (c) to measure stray electric fields and ion concentrations in the gas phase, (d) to test and improve the selectivity of the electric field ionization of high Rydberg states and (e) to observe for the first time the hyperfine structure in high- n , low- l molecular Rydberg states.

  20. Steady contemporary deformation of the central Basin and Range Province, western United States

    NASA Astrophysics Data System (ADS)

    Hammond, William C.; Blewitt, Geoffrey; Kreemer, Corné

    2014-06-01

    We use data from western U.S. GPS networks to estimate the rate, pattern, and style of tectonic deformation of the central Basin and Range Province (BRP). Previous geodetic investigations have found the crust of eastern Nevada and western Utah to act as a rigid microplate, with zero deformation rates to within measurement uncertainty. Observed transients in GPS time series have led others to propose a megadetachment model, predicting that the central BRP behaves as a microplate, but with time-varying translation. Here we reassess these hypotheses, benefiting from a significant increase in GPS stations and time span, and innovations in analysis techniques. Our results show that the BRP crust deforms everywhere and all the time. In a group of 24 stations between longitude -113.5° and -116.8°, we find strain rates of 1.9 ± 0.2 × 10-9 yr-1 extension directed N55°W and 2.2 ± 0.2 × 10-9 yr-1 contraction directed N35°E, inconsistent with microplate behavior. The linearity of time series of strain from GPS station triplets is inconsistent with episodic translation of quasi-rigid domains. One exception is station EGAN that exhibits nonlinear motion not found in adjacent stations. The dominant signal in Nevada is distributed shear consistent with Pacific/North America relative plate motion, suggesting that stresses are transmitted through the lithosphere at least 800 km from the plate boundary. The observed active extension is consistent with earthquake focal mechanisms and is in agreement with integrated rates estimated from earthquake geology. Our results do not support the proposed megadetachment in the BRP.

  1. Strength variation and deformational behavior in anisotropic granitic mylonites under high-temperature and -pressure conditions - An experimental study

    NASA Astrophysics Data System (ADS)

    Liu, Gui; Zhou, Yongsheng; Shi, Yaolin; Miao, Sheqiang; He, Changrong

    2017-03-01

    We performed deformation experiments on foliated granitic mylonites under high-temperature and -pressure conditions. To investigate the effects of pre-existing fabric properties on the rheology of the rocks, these experiments were carried out at different compression directions 30°, 45°, and 60° relative to the foliation, at temperatures of 600-850 °C, under confining pressures of 800-1200 MPa, within a strain rate range of 1 × 10-4/S - 2.5 × 10-6/S. The results of the experiments show that the deformation of three group samples is in the semi-brittle region at temperatures between 600 and 700 °C, and that the deformation of the samples transforms to plastic deformation by power-law creep with the stress exponent n = 3 ± 0.3 at temperatures between 800 and 850 °C. In the semi-brittle region, the mechanical data show that strength reaches its minimum value at an angle of 30° between the compression direction and the original foliation. In the plastic deformation regime, strength reaches its minimum value at an angle of 45° between the foliation and the orientation of the maximum principal stress. The strength with angles between 30° and 60° is lower than that of the compression direction perpendicular to foliation and the compression direction parallel to foliation. Microstructure analysis based on optical and electron microscopy of the deformation microstructures showed plastic deformation of aggregates of biotite and quartz at 800-850 °C. This deformation was extensive and formed new foliation. Quartz c-axis fabrics analysis by EBSD show that at temperatures of 600-700 °C, the c-axis fabric patterns could have been formed by the dominant activity of basal slip, similar with the starting granitic mylonite samples, but the dominant slip systems have been changed and transformed from basal slip to rhomb slip and prism slip at temperature of 800 °C and 850 °C. Microfractures were developed in hornblende and feldspar grains with local

  2. Decay out of the yrast and excited highly-deformed bands in the even-even nucleus {sup 134}Nd

    SciTech Connect

    Petrache, C.M.; Bazzacco, D.; Lunardi, S.

    1996-12-31

    The resolving power achieved by the new generation of {gamma}-ray detector arrays allows now to observe transitions with intensities of the order of {approximately}10{sup {minus}3} of the population of the final residual nucleus, making therefore feasible the study of the very weakly populated excited bands built on the superdeformed (SD) minimum or of the decay out of the SD bands. As a matter of fact, numerous excited SD bands have been observed in the different regions of superdeformation, which led to a deeper understanding of the single-particle excitation in the second minimum. The first experimental breakthrough in the study of the decay out process has been achieved in the odd-even {sup 133,135}Nd nuclei of the A=130 mass region. There, the observation of the discrete linking transitions has been favored by the relatively higher intensity of the highly-deformed (HD) bands ({approximately}10%), as well as by the small excitation energy with respect to the yrast line in the decay-out region ({approximately}1 MeV). No discrete linking transitions have been so far observed in the A=80, 150 mass regions. The present results suggest that the decay out of the HD bands in {sup 134}Nd is triggered by the crossing with the N=4 [402]5/2{sup +} Nilsson orbital, that has a smaller deformation than the corresponding N=6 intruder configuration. The crossing favours the mixing with the ND rotational bands strongly enhancing the decay-out process and weakening the in-band transition strength. The HD band becomes fragmented and looses part of its character. The intensity of the decay-out transitions increases when the spin of the HD state decreases, indicating enhanced ND amplitude in the wavefunction when going down the band. Lifetime measurements of the HD bands are crucial to further elucidate the decay-out process.

  3. Evolution of the structure upon heating of submicrocrystalline and nanocrystalline copper produced by high-rate deformation

    NASA Astrophysics Data System (ADS)

    Khomskaya, I. V.; Zel'Dovich, V. I.; Kheifets, A. E.; Frolova, N. Yu.; Dyakina, V. P.; Kazantsev, V. A.

    2011-04-01

    Methods of electron microscopy, dilatometry, and microhardness and resistivity measurements have been used to study the effect of annealing on the process of recrystallization of a mixed submicrocrys-talline+nanocrystalline (SMC+NC) structure of 99.8% copper produced by high-rate (˜105 s-1) deformation using dynamic channel angular pressing (DCAP). It has been shown that the SMC+NC structure of copper is thermally stable upon heating to a temperature of 150°C. It has been found that the ρ/ρ0 ratio of copper with an SMC+NC structure at a temperature of 4.2 K is considerably (by 5 times) higher than ρ/ρ0 of copper in the annealed coarse-grained state. This effect is due to a high concentration of defects and a high degree of dispersity of the copper structure after DCAP. Changes in the microhardness and in the resistivity (at a temperature of 4.2 K) of the SMC+NC copper after annealing characterize the level of relaxation processes.

  4. Evolution of the Structural-Phase State of a Ti-Al- V-Mo Alloy During Severe Plastic Deformation and SubSequent Annealing

    NASA Astrophysics Data System (ADS)

    Grabovetskaya, G. P.; Ratochka, I. V.; Mishin, I. P.; Zabudchenko, O. V.; Lykova, O. N.

    2016-05-01

    The effect of the initial phase composition of a Ti-Al-V-Mo alloy (VT16 according to Russian classification) on the evolution of its structural-phase state during the formation of ultrafine-grained structure and subsequent annealing is investigated by methods of optical and transmission electron microscopy and x-ray diffraction analysis. The structure is produced by cyclic pressing with a change of the deformation axis in each cycle combined with a gradual decrease of the pressing temperature from 1073 to 723 K. As this takes place, α″ → α + β and β → α phase transitions are found to develop in the test alloy. The phase state of the ultrafinegrained material thus produced depends for the most part on its elemental composition and severe plastic deformation regime. Annealing below the recrystallization temperature is shown to give rise to a β→α phase transition and alloying element redistribution. The foregoing processes allow for retaining a high level of the strength properties of the alloy.

  5. Near-surface neotectonic deformation associated with seismicity in the northeastern United States

    SciTech Connect

    Alexander, S.S.; Gold, D.P.; Gardner, T.W.; Slingerland, R.L.; Thornton, C.P. . Dept. of Geosciences)

    1989-10-01

    For the Lancaster, PA seismic zone a multifaceted investigation revealed several manifestations of near-surface, neotectonic deformation. Remote sensing data together with surface geological and geophysical observations, and recent seismicity reveal that the neotectonic deformation is concentrated in a NS-trending fault zone some 50 km in length and 10--20 km in width. Anomalies associated with this zone include distinctive lineament and surface erosional patterns; geologically recent uplift evidenced by elevations of stream terraces along the Susquehanna River; and localized contemporary travertine deposits in streams down-drainage from the inferred active fault zone. In the Moodus seismic zone the frequency of tectonically-controlled lineaments was observed to increase in the Moodus quadrangle compared to adjacent areas and dominant lineament directions were observed that are perpendicular and parallel to the orientation of the maximum horizontal stress direction (N80-85E) recently determined from in-situ stress measurements in a 1.5 km-deep borehole in the seismic zone and from well-constrained earthquake focal mechanisms. 284 refs., 33 figs.

  6. Performance of a precision high-density deformable mirror for extremely high contrast imaging astronomy from space

    NASA Astrophysics Data System (ADS)

    Trauger, John T.; Moody, Dwight; Gordon, Brian; Gürsel, Yekta; Ealey, Mark A.; Bagwell, Roger B.

    2003-02-01

    Active wavefront correction of a space telescope provides a technology path for extremely high contrast imaging astronomy at levels well beyond the capabilities of current telescope systems. A precision deformable mirror technology intended specifically for wavefront correction in a visible/near-infrared space telescope has been developed at Xinetics and extensively tested at JPL over the past several years. Active wavefront phase correction has been demonstrated to 1 Angstrom rms over the spatial frequency range accessible to a mirror with an array of actuators on a 1 mm pitch. It is based on a modular electroceramic design that is scalable to 1000s of actuator elements coupled to the surface of a thin mirror facesheet. It is controlled by a low-power multiplexed driver system. Demonstrated surface figure control, high actuator density, and low power dissipation are described. Performance specifications are discussed in the context of the Eclipse point design for a coronagraphic space telescope.

  7. GNSS seismometer: Seismic phase recognition of real-time high-rate GNSS deformation waves

    NASA Astrophysics Data System (ADS)

    Nie, Zhaosheng; Zhang, Rui; Liu, Gang; Jia, Zhige; Wang, Dijin; Zhou, Yu; Lin, Mu

    2016-12-01

    High-rate global navigation satellite systems (GNSS) can potentially be used as seismometers to capture short-period instantaneous dynamic deformation waves from earthquakes. However, the performance and seismic phase recognition of the GNSS seismometer in the real-time mode, which plays an important role in GNSS seismology, are still uncertain. By comparing the results of accuracy and precision of the real-time solution using a shake table test, we found real-time solutions to be consistent with post-processing solutions and independent of sampling rate. In addition, we analyzed the time series of real-time solutions for shake table tests and recent large earthquakes. The results demonstrated that high-rate GNSS have the ability to retrieve most types of seismic waves, including P-, S-, Love, and Rayleigh waves. The main factor limiting its performance in recording seismic phases is the widely used 1-Hz sampling rate. The noise floor also makes recognition of some weak seismic phases difficult. We concluded that the propagation velocities and path of seismic waves, macro characteristics of the high-rate GNSS array, spatial traces of seismic phases, and incorporation of seismographs are all useful in helping to retrieve seismic phases from the high-rate GNSS time series.

  8. Mechanical properties and constitutive relations for tantalum and tantalum alloys under high-rate deformation

    SciTech Connect

    Chen, S.R.; Gray, G.T. III; Bingert, S.R.

    1996-05-01

    Tantalum and its alloys have received increased interest as a model bcc metal and for defense-related applications. The stress-strain behavior of several tantalums, possessing varied compositions and manufacturing histories, and tantalum alloyed with tungsten, was investigated as a function of temperature from {minus}196 C to 1,000 C, and strain rate from 10{sup {minus}3} s{sup {minus}1} to 8,000 s{sup {minus}1}. The yield stress for all the Ta-materials was found to be sensitive to the test temperature, the impurity and solute contents; however, the strain hardening remained very similar for various ``pure`` tantalums but increased with alloying. Powder-metallurgy (P/M) tantalum with various levels of oxygen content produced via different processing paths was also investigated. Similar mechanical properties compared to conventionally processed tantalums were achieved in the P/M Ta. This data suggests that the frequently observed inhomogeneities in the mechanical behavior of tantalum inherited from conventional processes can be overcome. Constitutive relations based upon the Johnson-Cook, the Zerilli-Armstrong, and the Mechanical Threshold Stress models were evaluated for all the Ta-based materials. Parameters were also fit for these models to a tantalum-bar material. Flow stresses of a Ta bar stock subjected to a large-strain deformation of {var_epsilon} = 1.85 via multiple upset forging were obtained. The capabilities and limitations of each model for large-strain applications are examined. The deformation mechanisms controlling high-rate plasticity in tantalum are revisited.

  9. High temperature deformation behavior, thermal stability and irradiation performance in Grade 92 steel

    NASA Astrophysics Data System (ADS)

    Alsagabi, Sultan

    The 9Cr-2W ferritic-martensitic steel (i.e. Grade 92 steel) possesses excellent mechanical and thermophysical properties; therefore, it has been considered to suit more challenging applications where high temperature strength and creep-rupture properties are required. The high temperature deformation mechanism was investigated through a set of tensile testing at elevated temperatures. Hence, the threshold stress concept was applied to elucidate the operating high temperature deformation mechanism. It was identified as the high temperature climb of edge dislocations due to the particle-dislocation interactions and the appropriate constitutive equation was developed. In addition, the microstructural evolution at room and elevated temperatures was investigated. For instance, the microstructural evolution under loading was more pronounced and carbide precipitation showed more coarsening tendency. The growth of these carbide precipitates, by removing W and Mo from matrix, significantly deteriorates the solid solution strengthening. The MX type carbonitrides exhibited better coarsening resistance. To better understand the thermal microstructural stability, long tempering schedules up to 1000 hours was conducted at 560, 660 and 760°C after normalizing the steel. Still, the coarsening rate of M23C 6 carbides was higher than the MX-type particles. Moreover, the Laves phase particles were detected after tempering the steel for long periods before they dissolve back into the matrix at high temperature (i.e. 720°C). The influence of the tempering temperature and time was studied for Grade 92 steel via Hollomon-Jaffe parameter. Finally, the irradiation performance of Grade 92 steel was evaluated to examine the feasibility of its eventual reactor use. To that end, Grade 92 steel was irradiated with iron (Fe2+) ions to 10, 50 and 100 dpa at 30 and 500°C. Overall, the irradiated samples showed some irradiation-induced hardening which was more noticeable at 30°C. Additionally

  10. Field-induced expansion deformation in Pb islands on Cu(111): evidence from energy shift of empty quantum-well states.

    PubMed

    Chan, W Y; Huang, H S; Su, W B; Lin, W H; Jeng, H-T; Wu, M K; Chang, C S

    2012-04-06

    We use scanning tunneling microscopy and spectroscopy to measure the energy shift of empty quantum-well (QW) states in Pb islands on the Cu(111) surface. It is found that, with an increase of the electric field, the behavior of the energy shift can be grouped into two different modes for most QW states. In the first mode, the state energy moves toward high energy monotonically. In the second mode, the state energy shifts to a lower energy initially and then turns around to a higher energy. Moreover, we have observed that the QW states of higher energy behave in preference to the first mode, but they gradually change to the second mode as the Pb island becomes thicker. This thickness-dependent behavior reflects the existence of local expansion in the Pb islands, due to the electric field, and that the expansion is larger for a thicker island. QW states can thus be used for studying the localized lattice deformation in the nanometer scale.

  11. Deformation behavior of duplex austenite and ε-martensite high-Mn steel.

    PubMed

    Kwon, Ki Hyuk; Suh, Byeong-Chan; Baik, Sung-Il; Kim, Young-Woon; Choi, Jong-Kyo; Kim, Nack J

    2013-02-01

    Deformation and work hardening behavior of Fe-17Mn-0.02C steel containing ε-martensite within the austenite matrix have been investigated by means of in situ microstructural observations and x-ray diffraction analysis. During deformation, the steel shows the deformation-induced transformation of austenite → ε-martensite → α'-martensite as well as the direct transformation of austenite → α'-martensite. Based on the calculation of changes in the fraction of each constituent phase, we found that the phase transformation of austenite → ε-martensite is more effective in work hardening than that of ε-martensite → α'-martensite. Moreover, reverse transformation of ε-martensite → austenite has also been observed during deformation. It originates from the formation of stacking faults within the deformed ε-martensite, resulting in the formation of 6H-long periodic ordered structure.

  12. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    SciTech Connect

    Gussev, Maxim N.; Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; Terrani, Kurt A.

    2015-11-01

    The high resistance of cladding to plastic deformation and burst failure is one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) since the deformation and burst behavior governs the cooling efficiency of flow channels and process of fission product release. To simulate and evaluate such deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisted of a high-resolution video camera, light filtering unit, and monochromatic light sources, and the in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. In this study eleven (11) candidate cladding materials for ATF, i.e., 6 FeCrAl alloys and 5 nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800°C while negligible strain rates were measured for higher strength alloys and/or for relatively thick wall specimens.

  13. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    DOE PAGES

    Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; ...

    2015-08-25

    Here, one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) is high resistance of the cladding to plastic deformation and burst failure, since the deformation and burst behavior governs the cooling efficiency of flow channels and the process of fission product release. To simulate and evaluate the deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisting of a high-resolution video camera, a light filteringmore » unit, and monochromatic light sources. The in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. As the first application, ten (10) candidate cladding materials for ATF, i.e., five FeCrAl alloys and five nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800 °C, while negligible strain rates were measured for higher strength alloys.« less

  14. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    SciTech Connect

    Byun, Thak Sang; Yamamoto, Yukinori; Maloy, Stuart A.; Gussev, M. N.; Terrani, K. A.

    2015-08-25

    Here, one of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) is high resistance of the cladding to plastic deformation and burst failure, since the deformation and burst behavior governs the cooling efficiency of flow channels and the process of fission product release. To simulate and evaluate the deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisting of a high-resolution video camera, a light filtering unit, and monochromatic light sources. The in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. As the first application, ten (10) candidate cladding materials for ATF, i.e., five FeCrAl alloys and five nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800 °C, while negligible strain rates were measured for higher strength alloys.

  15. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    NASA Astrophysics Data System (ADS)

    Gussev, M. N.; Byun, T. S.; Yamamoto, Y.; Maloy, S. A.; Terrani, K. A.

    2015-11-01

    One of the most essential properties of accident tolerant fuel (ATF) for maintaining structural integrity during a loss-of-coolant accident (LOCA) is high resistance of the cladding to plastic deformation and burst failure, since the deformation and burst behavior governs the cooling efficiency of flow channels and the process of fission product release. To simulate and evaluate the deformation and burst process of thin-walled cladding, an in-situ testing and evaluation method has been developed on the basis of visual imaging and image analysis techniques. The method uses a specialized optics system consisting of a high-resolution video camera, a light filtering unit, and monochromatic light sources. The in-situ testing is performed using a 50 mm long pressurized thin-walled tubular specimen set in a programmable furnace. As the first application, ten (10) candidate cladding materials for ATF, i.e., five FeCrAl alloys and five nanostructured steels, were tested using the newly developed method, and the time-dependent images were analyzed to produce detailed deformation and burst data such as true hoop stress, strain (creep) rate, and failure stress. Relatively soft FeCrAl alloys deformed and burst below 800 °C, while negligible strain rates were measured for higher strength alloys.

  16. Large-deformation plasticity and acoustic emission of an Al-Mg alloy (1560) under high-temperature loading

    NASA Astrophysics Data System (ADS)

    Makarov, Plotnikov, V. A.; Lysikov, M. V.

    2017-07-01

    The following study investigates the large-deformation plasticity behavior and acoustic emission in Al-Mg alloy (1560) under high-temperature loading. The accumulation of deformation in the alloy, in conditions of change from room temperature to 500°C, occurs in two temperature intervals (I, II), characterized by different rates of deformation. The rate of deformation accumulation is correlated with acoustic emission. With load increasing in cycles from 40 to 200 MPa, the value of the boundary temperature (Tb) between intervals I and II changes non-monotonically. In cycles with load up to 90 MPa, the Tb value increases, while an increase up to 200 MPa makes Tb shift toward lower temperatures. This suggests that the shift of boundaries in the region of low temperatures and the appearance of high-amplitude pulses of acoustic emission characterize the decrease of the magnitude of thermal fluctuations with increasing mechanical load, leading to the rupture of interatomic bonds in an elementary deformation event.

  17. Constitutive Modeling of Hot Deformation Behavior of High-Strength Armor Steel

    NASA Astrophysics Data System (ADS)

    Bobbili, Ravindranadh; Madhu, Vemuri

    2016-05-01

    The hot isothermal compression tests of high-strength armor steel under a wide range of deformation temperatures (1100-1250 °C) and strain rates of (0.001-1/s) were performed. Based on the experimental data, constitutive models were established using the original Johnson-Cook (JC) model, modified JC model, and strain-compensated Arrhenius model, respectively. The modified JC model considers the coupled effects of strain hardening, strain rate hardening, and thermal softening. Moreover, the prediction accuracy of these developed models was determined by estimating the correlation coefficient ( R) and average absolute relative error (AARE). The results demonstrate that the flow behavior of high-strength armor steel is considerably influenced by the strain rate and temperature. The original JC model is inadequate to provide good description on the flow stress at evaluated temperatures. The modified JC model and strain-compensated Arrhenius model significantly enhance the predictability. It is also observed from the microstructure study that at low strain rates (0.001-0.01/s) and high temperatures (1200-1250 °C), a typical dynamic recrystallization (DRX) occurs.

  18. Demonstration of symmetric dark holes using two deformable mirrors at the high-contrast imaging testbed

    NASA Astrophysics Data System (ADS)

    Riggs, A. J. Eldorado; Groff, Tyler D.; Carlotti, Alexis; Kasdin, N. Jeremy; Cady, Eric J.; Kern, Brian D.; Kuhnert, Andreas

    2013-09-01

    The High Contrast Imaging Laboratory (HCIL) at Princeton has developed several important algorithms and technologies for space-based coronagraphy missions to detect earth-like exoplanets. Before June 2013 the HCIL was the only facility with two deformable mirrors (DMs) in series for focal plane wavefront control, which allows for quasi-static speckle correction on both sides of the image plane. From June through August 2013, the High- Contrast Imaging Testbed (HCIT) at JPL had a second DM installed. In this paper we report on the results of our Technology Development for Exoplanet Missions project to achieve high contrast in two symmetric dark holes using a shaped pupil (SP) coronagraph at the HCIT. Our previous experiment with a similar SP at the HCIT in 2007 yielded single-sided dark holes. That experiment utilized an iterative, batch-process wavefront estimator and Electric Field Conjugation for wavefront control. Our current tests use the faster Kalman filter estimator and the stroke minimization control algorithm. We use the same ripple-style SPs as in the previous HCIT experiment because that mask manufacturing technique proved successful. Our tests of symmetric dark holes in monochromatic light at the HCIT demonstrate Princeton's steady improvements in wavefront control and estimation techniques for a space-based coronagraphy mission.

  19. Monitoring and analysis of thermal deformation waves with a high-speed phase measurement system.

    PubMed

    Taylor, Lucas; Talghader, Joseph

    2015-10-20

    Thermal effects in optical substrates are vitally important in determining laser damage resistance in long-pulse and continuous-wave laser systems. Thermal deformation waves in a soda-lime-silica glass substrate have been measured using high-speed interferometry during a series of laser pulses incident on the surface. Two-dimensional images of the thermal waves were captured at a rate of up to six frames per thermal event using a quantitative phase measurement method. The system comprised a Mach-Zehnder interferometer, along with a high-speed camera capable of up to 20,000 frames-per-second. The sample was placed in the interferometer and irradiated with 100 ns, 2 kHz Q-switched pulses from a high-power Nd:YAG laser operating at 1064 nm. Phase measurements were converted to temperature using known values of thermal expansion and temperature-dependent refractive index for glass. The thermal decay at the center of the thermal wave was fit to a function derived from first principles with excellent agreement. Additionally, the spread of the thermal distribution over time was fit to the same function. Both the temporal decay fit and the spatial fit produced a thermal diffusivity of 5×10-7  m2/s.

  20. Laboratory experiments, high angular-resolution EBSD, and micromechanical modelling reveal residual stresses and their distribution in deformed olivine

    NASA Astrophysics Data System (ADS)

    Hansen, Lars; Wallis, David; Kempton, Imogen; Lebensohn, Ricardo; Wilkinson, Angus

    2017-04-01

    During high-temperature deformation of rocks, stresses are predicted to be distributed heterogeneously throughout the constituent grains. After unloading, much of this stress is potentially retained in the aggregate as residual stress, a phenomenon that may have large-scale geodynamic implications. After large stress changes in the solid Earth (e.g., glacial unloading or post-seismic relaxation), residual stresses can affect the immediate mechanical response of the rocks. Furthermore, examination of residual stresses in naturally deformed rocks additionally presents an opportunity to learn about ancient deformation events. These residual stresses arise from the anisotropic nature of the mechanical properties of minerals and from the heterogeneous substructures that form within grains (e.g., dislocation arrays and subgrain boundaries). This heterogeneity is therefore related to mechanical interactions on short (e.g., between individual dislocations), intermediate (e.g., between groups of dislocations), and long (e.g., between grains of differing orientation) spatial scales. We examine residual stresses in upper mantle analogues with three different methods. First, stress-dip tests were conducted on olivine single crystals at temperatures greater than 1250°C in a new uniaxial deformation apparatus with a piezoelectric actuator. These experiments reveal that the average residual stresses stored in deformed single crystals can be on the order of 50% of the applied differential stress. However, the magnitude of residual stress is likely a function of crystal orientation during deformation. Second, high angular-resolution electron backscatter diffraction (HR-EBSD) allows the residual stresses in deformed single crystals and polycrystals to be mapped with <1 micron spatial resolution. HR-EBSD mapping reveals stress heterogeneities on the order of differential stresses applied during deformation. Stresses averaged over each map are in reasonable agreement with the outcome

  1. Accuracy analysis of continuous deformation monitoring using BeiDou Navigation Satellite System at middle and high latitudes in China

    NASA Astrophysics Data System (ADS)

    Jiang, Weiping; Xi, Ruijie; Chen, Hua; Xiao, Yugang

    2017-02-01

    As BeiDou Navigation Satellite System (BDS) has been operational in the whole Asia-Pacific region, it means a new GNSS system with a different satellite orbit structure will become available for deformation monitoring in the future. Conversely, GNSS deformation monitoring data are always processed with a regular interval to form displacement time series for deformation analysis, where the interval can neither be too long from the time perspective nor too short from the precision of determined displacements angle. In this paper, two experimental platforms were designed, with one being at mid-latitude and another at higher latitude in China. BDS data processing software was also developed for investigating the accuracy of continuous deformation monitoring using current in-orbit BDS satellites. Data over 20 days at both platforms were obtained and were processed every 2, 4 and 6 h to generate 3 displacement time series for comparison. The results show that with the current in-orbit BDS satellites, in the mid-latitude area it is easy to achieve accuracy of 1 mm in horizontal component and 2-3 mm in vertical component; the accuracy could be further improved to approximately 1 mm in both horizontal and vertical directions when combined BDS/GPS measurements are employed. At higher latitude, however, the results are not as good as expected due to poor satellite geometry, even the 6 h solutions could only achieve accuracy of 4-6 and 6-10 mm in horizontal and vertical components, respectively, which implies that it may not be applicable to very high-precision deformation monitoring at high latitude using the current BDS. With the integration of BDS and GPS observations, however, in 4-h session, the accuracy can achieve 2 mm in horizontal component and 4 mm in vertical component, which would be an optimal choice for high-accuracy structural deformation monitoring at high latitude.

  2. Metastable alloy materials produced by solid state reaction of compacted, mechanically deformed mixtures

    DOEpatents

    Atzmon, M.; Johnson, W.L.; Verhoeven, J.D.

    1987-02-03

    Bulk metastable, amorphous or fine crystalline alloy materials are produced by reacting cold-worked, mechanically deformed filamentary precursors such as metal powder mixtures or intercalated metal foils. Cold-working consolidates the metals, increases the interfacial area, lowers the free energy for reaction, and reduces at least one characteristic dimension of the metals. For example, the grains of powder or the sheets of foil are clad in a container to form a disc. The disc is cold-rolled between the nip of rollers to form a flattened disc. The grains are further elongated by further rolling to form a very thin sheet of a lamellar filamentary structure containing filaments having a thickness of less than 0.01 microns. Thus, diffusion distance and time for reaction are substantially reduced when the flattened foil is thermally treated in oven to form a composite sheet containing metastable material dispersed in unreacted polycrystalline material. 4 figs.

  3. Jaw bone tissue state of stress and deformation investigation in process implantation

    NASA Astrophysics Data System (ADS)

    Sukharev, Michail P.; Tchurajev, Alexandr L.

    1992-06-01

    The aim of this investigation was studying the regularities of the strain distributions around in- bone implants of various shapes: cone, cylinder, tube, and blade-vent. Secondly, it was to study the force parameters of the cortical and porous bone substance when blade-vent implants of various size which are the distal supports of the bridge-shaped dentures are introduced into the planting bed. By means of the histological radiology method we carried out a study of the upper and lower jaws architectures on the basis of jaw segments investigation. A study was carried out by means of holographic interferometry of compression and tension areas distribution in the skull bones, the upper and lower jaws and temporo mandibular joint area under load. A laser holographic set-up used to obtain interference patterns covering strained and deformed jaws containing introduced implants consisted of a He-Ne laser, mirrors, lenses, a hologram, a VC, a TV monitor, and loading device.

  4. Maximum elastic deformations of compact stars with exotic equations of state.

    PubMed

    Owen, Benjamin J

    2005-11-18

    I make the first estimates of maximum elastic quadrupole deformations sustainable by alternatives to conventional neutron stars. Solid strange quark stars might sustain maximum ellipticities (dimensionless quadrupoles) up to a few times rather than a few times for conventional neutron stars, and hybrid quark-baryon or meson-condensate stars might sustain up to . Most of the difference is due to the shear modulus, which can be up to rather than in the inner crust of a conventional neutron star. Maximum solid strange star ellipticities are comparable to upper limits obtained for several known pulsars in a recent gravitational-wave search by LIGO. Maximum ellipticities of the more robust hybrid model will be detectable by LIGO at initial design sensitivity. A large shear modulus also strengthens the case for starquakes as an explanation for frequent pulsar glitches.

  5. In situ observation of crystallographic preferred orientation of deforming olivine at high pressure and high temperature

    NASA Astrophysics Data System (ADS)

    Ohuchi, T.; Nishihara, Y.; Seto, Y.; Kawazoe, T.; Nishi, M.; Maruyama, G.; Hashimoto, M.; Higo, Y.; Funakoshi, K. I.; Suzuki, A.; Kikegawa, T.; Irifune, T.

    2015-12-01

    Olivine is the main constituent mineral in Earth's upper mantle, and its crystallographic preferred orientation (CPO) controls the seismic anisotropy in the upper mantle. Because the relationship between fabric strength and seismic anisotropy shows an exponential form (Ismail and Mainprice, 1998), seismic anisotropy in the upper mantle is expected to have an upperlimit value. Hansen et al., (2014) demonstrated that a steady-state fabric of olivine is not reached until a very large shear strain (γ> 10) and fabric strength of olivine increases up to the J-index of 10-30 at 0.3 GPa. However, the strain dependency on the fabric strength of olivine needs to be evaluated at asthenospheric upper mantle pressures (2-13 GPa) because the relative activity of each slip system in olivine changes depending on pressure (e.g., Raterron et al., 2007). We experimentally evaluated the strain dependency of fabric strength of olivine in simple-shear geometry under upper mantle conditions (pressures of 1.3-3.8 GPa and temperatures of 1223-1573 K). The CPO of olivine was calculated from in-situ two-dimensional X-ray diffraction patterns. In the calculation, we simulated the optimized CPO which reproduces the two-dimensional X-ray diffraction pattern adopted from the experiments. The steady-state fabric strength of the A-type fabric was achieved within total shear strain of γ = 2. At strains higher than γ = 1, an increase in concentration of the [010] axes mainly contributes to an increase in fabric strength. At strains higher than γ = 2, the magnitude of VSH/VSV (i.e., ratio of horizontally and vertically polarized shear wave velocities) scarcely increased in most of the runs. The VSH/VSV of peridotite having the steady-state A-type olivine fabric coincides with that of recent global one-dimensional models under the assumption of horizontal flow, suggesting that the seismic anisotropy observed in the shallow upper mantle is mostly explained by the development of A-type olivine

  6. TRP 9904 - Constitutive Behavior of High Strength Multiphase Sheel Steel Under High Strain Rate Deformation

    SciTech Connect

    David Matlock; John Speer

    2005-03-31

    The focus of the research project was to systematically assess the strain rate dependence of strengthening mechanisms in new advanced high strength sheet steels. Data were obtained on specially designed and produced Duel Phase and TRIP steels and compared to the properties of automotive steels currently in use.

  7. Subsurface deformation in hypervelocity cratering experiments into high-porosity tuffs

    NASA Astrophysics Data System (ADS)

    Winkler, Rebecca; Poelchau, Michael H.; Moser, Stefan; Kenkmann, Thomas

    2016-10-01

    Hypervelocity impact experiments on porous tuff targets were carried out to determine the effect of porosity on deformation mechanisms in the crater's subsurface. Blocks of Weibern Tuff with about 43% porosity were impacted by 2.5 mm and 12.0 mm diameter steel spheres with velocities between 4.8 km s-1 and 5.6 km s-1. The postimpact subsurface damage was quantified with computer tomography as well as with meso- and microscale analyses of the bisected crater subsurface. The intensity and style of deformation in mineral clasts and the tuff matrix were mapped and their decay with subsurface depth was determined. Subsurface deformation styles include pore space compaction, clast rotation, as well as microfracture formation. Evaluation of the deformation indicates near-surface energy coupling at a calculated depth of burial of 2 projectile diameters (dp), which is in conflict with the crater shape, which displays a deep, central penetration tube. Subsurface damage extends to 2 dp beneath the crater floor in the experiments with 2.5 mm projectiles and increases to 3 dp for 12 mm projectiles. Based on overprinting relationships and the geometrical orientation of deformation features, a sequence of subsurface deformation events was derived (1) matrix compaction, (2) intragranular crack formation in clasts, (3) deformation band formation in the compacted matrix, (4) tensile fracturing.

  8. High-power visible-laser effect on a 37-segment Iris AO deformable mirror

    NASA Astrophysics Data System (ADS)

    Norton, Andrew; Gavel, Donald; Dillon, Daren

    2010-02-01

    We have tested an aluminum-coated Iris AO Micro-Electrical Mechanical System (MEMS) segmented Deformable Mirror (DM) for its behavior in the presence of high energy 532 nm laser light. The DM was subject to several tests in which the laser power and the duration of its incidence was varied. The DM experienced an irradiance of 94.5 W cm-2 at the maximum laser power of 2 W. A slight permanent reduction in the amount of bow in each segment was observed. This is most likely due to annealing. The mirror remained fully functional during and after the tests. Measurements of the mirror's temporal stability and position repeatability were performed before the laser test. We found a 1.28 nm rms variation in the bow of segments that is highly correlated over the 16 minute test. The mirror's ability to return to its initial position was within the 1.34 nm rms instrument noise. These results are encouraging for applications such as the laser uplink correction of the Visible Light Laser Guidestar Experiment (Villages) and future multi-Laser Guidestar systems (LGS).

  9. Adaptive Optics System with Deformable Composite Mirror and High Speed, Ultra-Compact Electronics

    NASA Astrophysics Data System (ADS)

    Chen, Peter C.; Knowles, G. J.; Shea, B. G.

    2006-06-01

    We report development of a novel adaptive optics system for optical astronomy. Key components are very thin Deformable Mirrors (DM) made of fiber reinforced polymer resins, subminiature PMN-PT actuators, and low power, high bandwidth electronics drive system with compact packaging and minimal wiring. By using specific formulations of fibers, resins, and laminate construction, we are able to fabricate mirror face sheets that are thin (< 2mm), have smooth surfaces and excellent optical shape. The mirrors are not astigmatic and do not develop surface irregularities when cooled. The actuators are small footprint multilayer PMN-PT ceramic devices with large stroke (2- 20 microns), high linearity, low hysteresis, low power, and flat frequency response to >2 KHz. By utilizing QorTek’s proprietary synthetic impendence power supply technology, all the power, control, and signal extraction for many hundreds to 1000s of actuators and sensors can be implemented on a single matrix controller printed circuit board co-mounted with the DM. The matrix controller, in turn requires only a single serial bus interface, thereby obviating the need for massive wiring harnesses. The technology can be scaled up to multi-meter aperture DMs with >100K actuators.

  10. A high throughput approach for analysis of cell nuclear deformability at single cell level

    NASA Astrophysics Data System (ADS)

    Ermis, Menekse; Akkaynak, Derya; Chen, Pu; Demirci, Utkan; Hasirci, Vasif

    2016-11-01

    Various physiological and pathological processes, such as cell differentiation, migration, attachment, and metastasis are highly dependent on nuclear elasticity. Nuclear morphology directly reflects the elasticity of the nucleus. We propose that quantification of changes in nuclear morphology on surfaces with defined topography will enable us to assess nuclear elasticity and deformability. Here, we used soft lithography techniques to produce 3 dimensional (3-D) cell culture substrates decorated with micron sized pillar structures of variable aspect ratios and dimensions to induce changes in cellular and nuclear morphology. We developed a high content image analysis algorithm to quantify changes in nuclear morphology at the single-cell level in response to physical cues from the 3-D culture substrate. We present that nuclear stiffness can be used as a physical parameter to evaluate cancer cells based on their lineage and in comparison to non-cancerous cells originating from the same tissue type. This methodology can be exploited for systematic study of mechanical characteristics of large cell populations complementing conventional tools such as atomic force microscopy and nanoindentation.

  11. A high throughput approach for analysis of cell nuclear deformability at single cell level

    PubMed Central

    Ermis, Menekse; Akkaynak, Derya; Chen, Pu; Demirci, Utkan; Hasirci, Vasif

    2016-01-01

    Various physiological and pathological processes, such as cell differentiation, migration, attachment, and metastasis are highly dependent on nuclear elasticity. Nuclear morphology directly reflects the elasticity of the nucleus. We propose that quantification of changes in nuclear morphology on surfaces with defined topography will enable us to assess nuclear elasticity and deformability. Here, we used soft lithography techniques to produce 3 dimensional (3-D) cell culture substrates decorated with micron sized pillar structures of variable aspect ratios and dimensions to induce changes in cellular and nuclear morphology. We developed a high content image analysis algorithm to quantify changes in nuclear morphology at the single-cell level in response to physical cues from the 3-D culture substrate. We present that nuclear stiffness can be used as a physical parameter to evaluate cancer cells based on their lineage and in comparison to non-cancerous cells originating from the same tissue type. This methodology can be exploited for systematic study of mechanical characteristics of large cell populations complementing conventional tools such as atomic force microscopy and nanoindentation. PMID:27841297

  12. (p,q) deformations and (p,q)-vector coherent states of the Jaynes-Cummings model in the rotating wave approximation

    SciTech Connect

    Ben Geloun, Joseph; Govaerts, Jan; Hounkonnou, M. Norbert

    2007-03-15

    Classes of (p,q) deformations of the Jaynes-Cummings model in the rotating wave approximation are considered. Diagonalization of the Hamiltonian is performed exactly, leading to useful spectral decompositions of a series of relevant operators. The latter include ladder operators acting between adjacent energy eigenstates within two separate infinite discrete towers, except for a singleton state. These ladder operators allow for the construction of (p,q)-deformed vector coherent states. Using (p,q) arithmetics, explicit and exact solutions to the associated moment problem are displayed, providing new classes of coherent states for such models. Finally, in the limit of decoupled spin sectors, our analysis translates into (p,q) deformations of the supersymmetric harmonic oscillator, such that the two supersymmetric sectors get intertwined through the action of the ladder operators as well as in the associated coherent states.

  13. Deformation mechanisms for high-temperature creep of high yttria content stabilized zirconia single crystals

    SciTech Connect

    Gomez-Garcia, D.; Martinez-Fernandez, J.; Dominguez-Rodriguez, A.; Eveno, P.; Castaing, J.

    1996-03-01

    Creep of 21 mol.% yttria-stabilized zirconia single crystals has been studied between 1,400 and 1,800 C. The creep parameters have been determined indicating a change of the controlling mechanism around 1,500 C. At higher temperatures recovery creep is found to be the rate controlling mechanism, with a stress exponent {approx_equal} 3 and an activation energy {approx_equal} 6 eV. Transition to glide controlled creep occurs below 1,500 C, associated with larger stress exponents ({approx_equal} 5) and activation energies ({approx_equal} 8.5 eV). TEM observations of the dislocation microstructure confirm this transition. The influence of the high yttria content, which is at the origin of the high creep resistance of these crystals, is discussed for each range of temperatures.

  14. Efficient High-Pressure State Equations

    NASA Technical Reports Server (NTRS)

    Harstad, Kenneth G.; Miller, Richard S.; Bellan, Josette

    1997-01-01

    A method is presented for a relatively accurate, noniterative, computationally efficient calculation of high-pressure fluid-mixture equations of state, especially targeted to gas turbines and rocket engines. Pressures above I bar and temperatures above 100 K are addressed The method is based on curve fitting an effective reference state relative to departure functions formed using the Peng-Robinson cubic state equation Fit parameters for H2, O2, N2, propane, methane, n-heptane, and methanol are given.

  15. Efficient High-Pressure State Equations

    NASA Technical Reports Server (NTRS)

    Harstad, Kenneth G.; Miller, Richard S.; Bellan, Josette

    1997-01-01

    A method is presented for a relatively accurate, noniterative, computationally efficient calculation of high-pressure fluid-mixture equations of state, especially targeted to gas turbines and rocket engines. Pressures above I bar and temperatures above 100 K are addressed The method is based on curve fitting an effective reference state relative to departure functions formed using the Peng-Robinson cubic state equation Fit parameters for H2, O2, N2, propane, methane, n-heptane, and methanol are given.

  16. Towards a high resolution inventory of anthropogenic deformation in North America using InSAR

    NASA Astrophysics Data System (ADS)

    Pritchard, M. E.; Lohman, R. B.; Taylor, H.; Semple, A.; Valentino, B.

    2015-12-01

    Anthropogenic surface deformation is important to measure for several reasons -- 1) it could be a hazard to infrastructure; 2) it could contaminate precise measurements of other types of deformation (e.g., magmatic or tectonic); and 3) the deformation can provide otherwise inaccessible information about the subsurface as we measure the Earth's response to known pumping, surface change, or mining activity. While there are studies at individual sites in North America that demonstrate these three types of studies, we lack a continental synoptic view of anthropogenic deformation and its significance. To fill this gap, we use satellite Interferometric Synthetic Aperture Radar (InSAR) data to image ground deformation across the continent with a spatial resolution of 1 km/pixel or better using results from the literature as well as new analysis of more than 5000 interferograms from the ERS, Envisat, and ALOS satellites, which collectively span 1992-2011. Our compilation is not complete in terms of spatially or temporal coverage nor is it uniform in quality over the region -- certainly we have missed some areas of deformation. Most of the data analyzed is in the western US, but ALOS observations east of the Rocky Mountains are of good quality even in vegetated and snowy areas and we document mining subsidence greater than several cm per year in NY, PA, and WV. We catalog more than 200 anthropogenic deformation signals, including about 45 that are not previously reported. The majority of these deformation sources can be attributed to groundwater extraction (66%), 8% to geothermal activity, 13% to hydrocarbon extraction, 11% to mining activity, and 2% to other sources such as lake loading. In a few areas, the source of deformation is not yet determined. As expected, most deformation is time dependent and so continuous monitoring is needed. In some areas, comparisonbetween pumping records and surface deformation reveals some suprises. For example, at the East Mesa Geothermal

  17. The deformation response of three-dimensional woven composites subjected to high rates of loading

    NASA Astrophysics Data System (ADS)

    Pankow, Mark Robert

    The use of polymer matrix composites is widespread, with development in automotive, aerospace and recreational equipment. These applications have produced loading scenarios which are unfamiliar and not well understood. Several applications involve impact loading, which produces large strain rates and delamination failure. New manufacturing methods have led to three dimensional (3D) weave geometries that provide composites with damage protection. This is accomplished through elimination of delamination, and localizing the extent of damage. The present work is a combined experimental and computational study aimed at developing a mechanism based deformation response model for 3D woven composites, including the prediction of failure strengths at high loading rates. Three unique experimental configurations have been developed; along with finite element based simulations to predict the material response and failure mechanisms that are experimentally observed. End Notch Flexure (ENF) tests were used to determine the effectiveness of the Z-fiber at resisting crack propagation. The crack propagation was found to have rate dependent properties, with architecture based parameters required to predict the strength and resistance. The computational results reinforced the experimental observations. A new FE implementation captured the effectiveness of the Z-fiber reinforcement bridging the growing crack. Shock impact testing was performed to simulate the effects of blast loading on the material. New experimental measurement methods were utilized to record the deformations and strains which led to observations of matrix micro-cracking, the first failure mode. Computational models were developed to predict the material behavior subjected to shock loading, including matrix micro-cracking, which was predicted accurately. Finally, split Hopkinson pressure bar (SHPB) testing was done to understand the high strain rate behavior of the material in compression in all three directions. The

  18. Effects of different levels of compression during sub-maximal and high-intensity exercise on erythrocyte deformability.

    PubMed

    Wahl, Patrick; Bloch, Wilhelm; Mester, Joachim; Born, Dennis-Peter; Sperlich, Billy

    2012-06-01

    The aim of the study was to test the hypothesis whether different levels of sock compression (0, 10, 20, and 40 mmHg) affect erythrocyte deformability and metabolic parameters during sub-maximal and maximal running. Nine well-trained, male endurance athletes (age 22.2 ± 1.3 years, peak oxygen uptake 57.7 ± 4.5 mL min(-1) kg(-1)) carried out four periods of sub-maximal running at 70% of peak oxygen uptake for 30 min followed by a ramp test until exhaustion with and without compression socks that applied different levels of pressure. Erythrocyte deformability, blood lactate, heart rate and arterial partial pressure of oxygen (pO(2)) were monitored before and during all of these tests. Erythrocyte deformability, heart rate, pO(2) and lactate concentration were unaffected by compression, whereas exercise itself significantly increased erythrocyte deformability. However, the increasing effects of exercise were attenuated when high compression was applied. This first evaluation of the potential effects of increasing levels of compression on erythrocyte deformability and metabolic parameters during (sub-) maximal exercise, revealed no effects whatsoever.

  19. Approximate bound-states solution of the Dirac equation with some thermodynamic properties for the deformed Hylleraas plus deformed Woods-Saxon potential

    NASA Astrophysics Data System (ADS)

    Onyeaju, M. C.; Ikot, A. N.; Onate, C. A.; Ebomwonyi, O.; Udoh, M. E.; Idiodi, J. O. A.

    2017-07-01

    The Pekeris approximate scheme is introduced to deal with the centrifugal term in a Dirac equation with the deformed Hylleraas plus Woods-Saxon (DHWS) potential model. The relativistic energy solutions for the spin and pseudospin symmetries are obtained via the Nikiforov-Uvarov (NU) method. In the non-relativistic limits we calculated the thermodynamics properties for some selected diatomic molecules.

  20. Study of a wide-aperture combined deformable mirror for high-power pulsed phosphate glass lasers

    SciTech Connect

    Samarkin, V V; Aleksandrov, A G; Romanov, P N; Rukosuev, A L; Kudryashov, A V; Jitsuno, T

    2015-12-31

    A deformable mirror with the size of 410 × 468 mm controlled by bimorph piezoceramic plates and multilayer piezo stacks is developed. The response functions of individual actuators and the measurements of the flatness of the deformable mirror surface are presented. The study of mirrors with an interferometer and a wavefront sensor has shown that it is possible to improve the surface flatness down to a residual roughness of 0.033 μm (RMS). The possibility of correction of beam aberrations in an ultra-high-power laser using the created bimorph mirror is demonstrated. (letters)

  1. Microstructure of YBa2Cu3O y subjected to severe plastic deformation by high pressure torsion

    NASA Astrophysics Data System (ADS)

    Kuznetsova, E. I.; Degtyarev, M. V.; Zyuzeva, N. A.; Bobylev, I. B.; Pilyugin, V. P.

    2017-08-01

    The influence of plastic deformation carried out by high pressure torsion at room temperature on the microstructure of the YBa2Cu3O y (123) compound prepared by standard ceramic technology and annealed at low temperature (200°C) in a water-saturated atmosphere has been studied. It has been shown that the directional growth of recrystallized lamellar-shaped grains initiated by the 124-123 phase transformation takes place upon recovery (after deformation) annealing at 930°C in ceramics subjected to additional low-temperature annealing, which leads to the formation of the texture. A rodlike structure has been observed in samples prepared by standard technology, after deformation and recovery annealing (930°C).

  2. Mossbauer analysis of deformation dissolution of the products of cellular decomposition in high-nitrogen chromium manganese austenite steel

    NASA Astrophysics Data System (ADS)

    Shabashov, V. A.; Korshunov, L. G.; Sagaradze, V. V.; Kataeva, N. V.; Zamatovsky, A. E.; Litvinov, A. V.; Lyashkov, K. A.

    2014-03-01

    Methods of Mossbauer spectroscopy and electron microscopy analysis of high-nitrogen chromium manganese steel FeMn22Cr18N0.8 have been used to investigate the processes of dissolution of the products of cellular decomposition in austenite matrix upon severe deformation under the conditions of dry sliding friction and shear under pressure in Bridgman anvils. Deformation-induced redistribution of nitrogen from the chromium nitrides to interstitial positions of the quenched and preliminary aged steel has been determined. According to the data of Mossbauer analysis the depth of dissolution of chromium nitrides and the increase of content of nitrogen in steel matrix upon friction is 10 μn and more. Aging decreases the amount of nitrogen which transfers to the solid solution under deformation. This is a factor of the enhanced adhesive wear in the aged samples.

  3. Characterization of High Temperature Deformation Behavior of BFe10-1-2 Cupronickel Alloy Using Orthogonal Analysis

    NASA Astrophysics Data System (ADS)

    Cai, Jun; Wang, Kuaishe; Zhang, Xiaolu; Wang, Wen

    2017-07-01

    High temperature deformation behavior of BFe10-1-2 cupronickel alloy was investigated by means of isothermal compression tests in the temperature range of 1,023 1,273 K and strain rate range of 0.001 10 s-1. Based on orthogonal experiment and variance analysis, the significance of the effects of strain, strain rate and deformation temperature on the flow stress was evaluated. Thereafter, a constitutive equation was developed on the basis of the orthogonal analysis conclusions. Subsequently, standard statistical parameters were introduced to verify the validity of developed constitutive equation. The results indicated that the predicted flow stress values from the constitutive equation could track the experimental data of BFe10-1-2 cupronickel alloy under most deformation conditions.

  4. Initial state geometry and fluctuations in deformed and asymmetric nuclear collisions in the IP-Glasma framework

    NASA Astrophysics Data System (ADS)

    Schenke, Björn; Tribedy, Prithwish; Venugopalan, Raju

    2014-11-01

    The IP-Glasma model of initial conditions based on the ab initio color glass condensate framework successfully explains most of the bulk features of the global data for various systems like p+p, p+A and A+A over a wide range of energies. We employ this framework to study deformed U+U collisions, asymmetric Cu+Au collisions and the effect of deformation in Au+Au collisions at RHIC. A combined study of these heavy ion systems with varying initial geometries can provide a unique opportunity to determine the origin of different sources of fluctuations that affect global observables like multiplicity and flow. We study the sensitivity of multiplicity, eccentricity and their event-by-event distributions to the details of initial state geometry. Results are compared to a two-component MC-Glauber model implementation that includes Negative-Binomial multiplicity fluctuations. We argue that the measurements of global observables for these systems at RHIC can constrain the mechanism of multi-particle production.

  5. Mechanical and structural aspects of high-strain-rate deformation of NiTi alloy

    NASA Astrophysics Data System (ADS)

    Bragov, A. M.; Danilov, A. N.; Konstantinov, A. Yu.; Lomunov, A. K.; Motorin, A. S.; Razov, A. I.

    2015-04-01

    The mechanical behavior of the binary polycrystalline NiTi alloy with a quasi-equilibrium structure has been considered in the course of the high-strain-rate extension in a temperature range of 20-300°C. The quasi-equilibrium structure, which is necessary to ensure the long-term stability of special properties of the alloy, was achieved using aging, after which both the forward and reverse martensitic transformations exhibited a multistage character and the phase composition at room temperature was characterized by the presence of R and B19' martensites. To separate the contributions that come from the equilibrium structure and from the high rate of tension to the mechanical behavior of the alloy, a comparative analysis of the diagrams of high-strain-rate and quasi-static tension has been performed. It has been shown that the action of several mechanisms of reversible deformation is determined by the specific features of the equilibrium structure, and the level of stresses at which these mechanisms are developed is controlled by the rate of tension. The results of the X-ray diffraction study of the phase composition of the alloy samples after high-strain-rate tension, which make it possible to conclude that the mechanical behavior of martensite and austenite upon the dynamic tension of the alloy is determined by the development of stress-induced R → B19', B2 → R, and B2 → B19' transformations and by the processes of the detwinning and reorientation of crystals of B19' martensite, are given.

  6. Toward high-speed 3D nonlinear soft tissue deformation simulations using Abaqus software.

    PubMed

    Idkaidek, Ashraf; Jasiuk, Iwona

    2015-12-01

    We aim to achieve a fast and accurate three-dimensional (3D) simulation of a porcine liver deformation under a surgical tool pressure using the commercial finite element software Abaqus. The liver geometry is obtained using magnetic resonance imaging, and a nonlinear constitutive law is employed to capture large deformations of the tissue. Effects of implicit versus explicit analysis schemes, element type, and mesh density on computation time are studied. We find that Abaqus explicit and implicit solvers are capable of simulating nonlinear soft tissue deformations accurately using first-order tetrahedral elements in a relatively short time by optimizing the element size. This study provides new insights and guidance on accurate and relatively fast nonlinear soft tissue simulations. Such simulations can provide force feedback during robotic surgery and allow visualization of tissue deformations for surgery planning and training of surgical residents.

  7. Geometry and deformation history of the New Madrid seismic zone fault system, Central U.S. from high-resolution marine seismic reflection data, and implications for intraplate deformation

    NASA Astrophysics Data System (ADS)

    Guo, L.; Magnani, M.; McIntosh, K. D.; Waldron, B. A.; Saustrup, S.; Fave, X. J.

    2010-12-01

    The New Madrid Seismic Zone (NMSZ) is the most seismically active area in the continental United States east of the Rocky Mountains, and by far the most studied intraplate seismic zone in the world. The occurrence of large magnitude historical and prehistorical earthquakes, as well as the high level of instrumental seismicity suggest that the North American plate is actively deforming in this region. This observation appears to clash with geodetic evidence that shows minimal motion across the faults illuminated by the present seismicity, suggesting that either the present GPS vectors recorded at the surface are not typical of the long term deformation rate of the NMSZ faults, or that the NMSZ fault system is presently unloaded and not deforming. To better constrain the long-term deformation history of the NMSZ fault system, in the summer of 2010 we acquired ~300 km of high-resolution seismic marine reflection data along the Mississippi River from Cape Girardeau, MO to Caruthersville, MO. The profile crosses a large portion of the Mississippi Embayment, including three of the four main NMSZ active faults, and images the gently south-dipping unconsolidated sediments of the Mississippi Embayment from the Quaternary alluvium of the Mississippi River down to the top of Paleozoic sequences, at a depth of ~650 m. Among the most remarkable structures imaged by the profile is the Reelfoot fault, interpreted as the NW-SE striking restraining bend connecting two NE-SW trending dextral strike-slip faults. The Reelfoot thrust intersects the profile at three locations along the river meander known as the Kentucky Bend. The multiple crossings allow mapping of the along-strike variations of the fault plane’s dip and structure. In particular the data show that a reverse offset of 42 m at the top of the Cretaceous is accommodated by a single fault at the crossing north of town of Tiptonville, TN, west of the location where the Reelfoot thrust ruptured during the 7 February 1812 M7

  8. Metastable alloy materials produced by solid state reaction of compacted, mechanically deformed mixtures

    DOEpatents

    Atzmon, Michael; Johnson, William L.; Verhoeven, John D.

    1987-01-01

    Bulk metastable, amorphous or fine crystalline alloy materials are produced by reacting cold-worked, mechanically deformed filamentary precursors such as metal powder mixtures or intercalated metal foils. Cold-working consolidates the metals, increases the interfacial area, lowers the free energy for reaction, and reduces at least one characteristic dimension of the metals. For example, the grains (13) of powder or the sheets of foil are clad in a container (14) to form a disc (10). The disc (10) is cold-rolled between the nip (16) of rollers (18,20) to form a flattened disc (22). The grains (13) are further elongated by further rolling to form a very thin sheet (26) of a lamellar filamentary structure (FIG. 4) containing filaments having a thickness of less than 0.01 microns. Thus, diffusion distance and time for reaction are substantially reduced when the flattened foil (28) is thermally treated in oven (32) to form a composite sheet (33) containing metastable material (34) dispersed in unreacted polycrystalline material (36).

  9. SU(3) gauge symmetry for collective rotational states in deformed nuclei

    NASA Astrophysics Data System (ADS)

    Rosensteel, George; Sparks, Nick

    2016-09-01

    How do deformed nuclei rotate? The qualitative answer is that a velocity-dependent interaction causes a strong coupling between the angular momentum and the vortex momentum (or Kelvin circulation). To achieve a quantitative explanation, we propose a significant extension of the Bohr-Mottelson legacy model in which collective wave functions are vector-valued in an irreducible representation of SU(3). This SU(3) is not the usual Elliott choice, but rather describes internal vorticity in the rotating frame. The circulation values C of an SU(3) irreducible representation, say the (8,0) for 20Ne, are C = 0, 2, 4, 6, 8, which is the same as the angular momentum spectrum in the Elliott model; the reason is a reciprocity theorem in the symplectic model. The differential geometry of Yang-Mills theory provides a natural mathematical framework to solve the angular-vortex coupling riddle. The requisite strong coupling is a ``magnetic-like'' interaction arising from the covariant derivative and the bundle connection. The model builds on prior work about the Yang-Mills SO(3) gauge group model.

  10. High-spin states of ZXRh

    SciTech Connect

    Piel W.F. Jr.; Scharff-Goldhaber, G.; Lister, C.J.; Varley, B.J.

    1986-02-01

    High-spin states of ZXRh up to J = ((31/2)) and an excitation energy of 7.1 MeV were established by means of the WNi(UCa,3pel)ZXRh reaction. The states are found to decay through two separate el-ray cascades with the assignments for the lower-spin states being in agreement with previous work. No strong evidence has been found for the existence of collectivity induced by intruder states. The empirical excitation energies are compared to those found recently for the nearby even-A isotones ZWRu and ZYPd, and the systematics of the N = 52 nuclides are discussed.

  11. Three-dimensionally deformable, highly stretchable, permeable, durable and washable fabric circuit boards

    PubMed Central

    Li, Qiao; Tao, Xiao Ming

    2014-01-01

    This paper reports fabric circuit boards (FCBs), a new type of circuit boards, that are three-dimensionally deformable, highly stretchable, durable and washable ideally for wearable electronic applications. Fabricated by using computerized knitting technologies at ambient dry conditions, the resultant knitted FCBs exhibit outstanding electrical stability with less than 1% relative resistance change up to 300% strain in unidirectional tensile test or 150% membrane strain in three-dimensional ball punch test, extraordinary fatigue life of more than 1 000 000 loading cycles at 20% maximum strain, and satisfactory washing capability up to 30 times. To the best of our knowledge, the performance of new FCBs has far exceeded those of previously reported metal-coated elastomeric films or other organic materials in terms of changes in electrical resistance, stretchability, fatigue life and washing capability as well as permeability. Theoretical analysis and numerical simulation illustrate that the structural conversion of knitted fabrics is attributed to the effective mitigation of strain in the conductive metal fibres, hence the outstanding mechanical and electrical properties. Those distinctive features make the FCBs particularly suitable for next-to-skin electronic devices. This paper has further demonstrated the application potential of the knitted FCBs in smart protective apparel for in situ measurement during ballistic impact. PMID:25383032

  12. High-temperature deformation processing of Ti-24Al-20Nb

    SciTech Connect

    Sagar, P.K.; Banerjee, D.; Muraleedharan, K.; Prasad, Y.V.R.K.

    1996-09-01

    Power dissipation maps have been generated in the temperature range of 900 C to 1,150 C and strain rate range of 10{sup {minus}3} to 10 s{sup {minus}1} for a cast aluminide alloy Ti-24Al-20Nb using dynamic material model. The results define two distinct regimes of temperature and strain rate in which efficiency of power dissipation is maximum. The first region, centered around 975 C/0.1 s{sup {minus}1}, is shown to correspond to dynamic recrystallization of the {alpha}{sub 2} phase and the second, centered around 1,150 C/0.001 s{sup {minus}1}, corresponds to dynamic recovery and superplastic deformation of the {beta} phase. Thermal activation analysis using the power law creep equation yielded apparent activation energies of 854 and 627 kJ/mol for the first and second regimes, respectively. Reanalyzing the data by alternate methods yielded activation energies in the range of 170 to 220 kJ/mol and 220 to 270 kJ/mol for the first and second regimes, respectively. Cross slip was shown to constitute the activation barrier in both cases. Two distinct regimes of processing instability--one at high strain rates and the other at the low strain rates in the lower temperature regions--have been identified, within which shear bands are formed.

  13. Some observations on cyclic deformation structures in the high-strength commercial aluminum alloy AA 7150

    SciTech Connect

    Hanlon, D.N.; Rainforth, W.M.

    1998-11-01

    Load-controlled fatigue testing of the aluminum alloy AA 7150 has been conducted using four-point bending with an R ratio of + 0.1 over a range of maximum stress levels from 60 to 120% of the 0.2% proof stress. The alloy, in the form of 12.5-mm rolled plate, was investigated in underaged (UA), peak-aged (PA), and overaged (OA) conditions, corresponding to a change in average precipitate sizes from 5 nm in the UA condition to 21 nm in the OA condition. Three orientations of the plate were investigated. Orientation and aging condition influenced the degree of surface topographical development but not fatigue life. Detailed transmission electron microscopy (TEM) of the fatigued surface indicated that deformation in all aging conditions occurred by planar slip. Slip was generally restricted to a single slip system within each grain, and subgrain boundaries offered little resistance to dislocation movement facilitating long slip line lengths (measured up to 310 {micro}m) between adjacent high-angle grain boundaries. Planar slip observed in the OA condition is attributed to shearing of large strengthening precipitates, which is promoted by long slip line lengths. No evidence of surface specific changes in slip character was observed.

  14. Microstructural evolution and mechanical properties of high strength magneisum alloys fabricated by deformation processing

    NASA Astrophysics Data System (ADS)

    Mansoor, Bilal

    The goal of this research was to develop high strength Mg by thermo-mechanical processing. Several novel techniques were developed to impart large plastic strains on Mg alloys and Mg based composites. The main emphasis of this work was on investigating the effect of different processing schemes on grain-refinement and texture modification of processed material. The room-temperature and elevated-temperature mechanical behavior of processed-Mg was studied in detail. Biaxial corrugated pressing, also known as alternate biaxial reverse corrugation processing was applied to twin-roll cast AZ31 Mg and warm-extruded ZK60 Mg. Friction stir processing to partial depths was applied to thixomolded AM60 Mg and warm-extruded ZK60 Mg. A new process called "bending reverse-bending", was developed and applied to hot rolled AZ31-H24 Mg. A Mg/Al laminated composite was developed by hot pressing and rolling. In processed condition, Mg alloys exhibit enhancement in room-temperature strength and ductility, as well as elevated temperature formability. It was concluded that improvement in mechanical properties of processed-Mg is strongly influenced by grain size and precipitates; while ductility largely depends on resulting deformation textures.

  15. State-by-State Analysis of High School Feedback Reports

    ERIC Educational Resources Information Center

    Data Quality Campaign, 2013

    2013-01-01

    The best information to help stakeholders evaluate and strengthen their efforts to improve students' college and career readiness is actual information about students' success beyond high school, such as enrollment, remediation, degree and certification completion, and employment outcomes. States have a critical role to plan in providing…

  16. Influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steels

    NASA Astrophysics Data System (ADS)

    Li, Junru; Liu, Jianjun; Jiang, Bo; Zhang, Chaolei; Liu, Yazheng

    2017-03-01

    The dissolution process of delta ferrites and the influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steel 10Cr12Ni3Mo2VN were studied by isothermal heating and thermal simulation experiments. The precipitation temperature of delta ferrites in experimental steel is about 1195 °C. M23C6-type carbides incline to precipitate and coarsen at the boundaries of delta ferrites below 930 °C, and can be rapidly dissolved by heating at 1180 °C. The percentage of delta ferrites gradually decreases with heating time. And a Kolmogorov-Johnson-Mehl-Avrami equation was established to describe the dissolution process of delta ferrites at 1180 °C. High temperature pre-deformation can markedly increase the dissolution rate of delta ferrites. Pre-deformation can largely increase the interface area between delta ferrite and matrix and thus increase the unit-time diffusing quantities of alloying elements between delta ferrites and matrix. In addition, high temperature pre-deformation leads to dynamic recrystallization and increases the number of internal grain boundaries in the delta ferrites. This can also greatly increase the diffusing rate of alloying elements. In these cases, the dissolution of delta ferrites can be promoted.

  17. Numerical modeling of mullions in the Taili high deformation zone, North China: Implications for the rheology of granitic rocks

    NASA Astrophysics Data System (ADS)

    Li, Zhiyong; Zeng, Zuoxun; Mohammed, Adil S.

    2017-05-01

    This paper presents a combined field measurement and finite element modeling analysis of the mullions occurring on the contact of two granitic rocks with different grain size in the Taili High-Strain Deformation Zone (THDZ), West Liaoning of North China. All of the field data are located in the plot zone of the modeling results. Numerical modeling results indicate that: (1) The inter-angle between the tangent lines cross the cusp point and the ratio R of amplitude and width of mullions are the most effective parameters to describe the geometric shape and evolution of mullions, as well as useful indicators of the rheology of rocks. (2) The competence contrast controls the growth rate of mullions under shortening. It determines the possible ratio R of final mullions. Moreover, decreasing of the cusp angle in high competence contrast materials is faster than that in low competence contrast model. (3) The initial disturbance is an essential factor for the generation of mullions. Those contacts with higher initial disturbance will develop into mullions more easily and have a high growth rate during the same shortening deformation regime. (4) The rheology and deformation behavior of the granitic rocks in the study area are primarily controlled by the grain sizes of quartz and feldspar. The effective viscosity ratio of biotite adamellite and granitic gneisses is about 0.01-0.5. The deformation mechanisms of these granitic rocks should be dominated by a grain-size-sensitive diffusion creep.

  18. Influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steels

    NASA Astrophysics Data System (ADS)

    Li, Junru; Liu, Jianjun; Jiang, Bo; Zhang, Chaolei; Liu, Yazheng

    2017-02-01

    The dissolution process of delta ferrites and the influence of high temperature pre-deformation on the dissolution rate of delta ferrites in martensitic heat-resistant steel 10Cr12Ni3Mo2VN were studied by isothermal heating and thermal simulation experiments. The precipitation temperature of delta ferrites in experimental steel is about 1195 °C. M23C6-type carbides incline to precipitate and coarsen at the boundaries of delta ferrites below 930 °C, and can be rapidly dissolved by heating at 1180 °C. The percentage of delta ferrites gradually decreases with heating time. And a Kolmogorov-Johnson-Mehl-Avrami equation was established to describe the dissolution process of delta ferrites at 1180 °C. High temperature pre-deformation can markedly increase the dissolution rate of delta ferrites. Pre-deformation can largely increase the interface area between delta ferrite and matrix and thus increase the unit-time diffusing quantities of alloying elements between delta ferrites and matrix. In addition, high temperature pre-deformation leads to dynamic recrystallization and increases the number of internal grain boundaries in the delta ferrites. This can also greatly increase the diffusing rate of alloying elements. In these cases, the dissolution of delta ferrites can be promoted.

  19. On the deformation mechanisms and electrical behavior of highly stretchable metallic interconnects on elastomer substrates

    NASA Astrophysics Data System (ADS)

    Arafat, Yeasir; Dutta, Indranath; Panat, Rahul

    2016-09-01

    Flexible metallic interconnects are highly important in the emerging field of deformable/wearable electronics. In our previous work [Arafat et al., Appl. Phys. Lett. 107, 081906 (2015)], interconnect films of Indium metal, periodically bonded to an elastomer substrate using a thin discontinuous/cracked adhesion interlayer of Cr, were shown to sustain a linear strain of 80%-100% without failure during repeated cycling. In this paper, we investigate the mechanisms that allow such films to be stretched to a large strain without rupture along with strategies to prevent a deterioration in their electrical performance under high linear strain. Scanning Electron Microscopy and Digital Image Correlation are used to map the strain field of the Cr adhesion interlayer and the In interconnect film when the elastomer substrate is stretched. It is shown that the Cr interlayer morphology, consisting of islands separated by bi-axial cracks, accommodates the strain primarily by widening of the cracks between the islands along the tensile direction. This behavior is shown to cause the strain in the In interconnect film to be discontinuous and concentrated in bands perpendicular to the loading direction. This localization of strain at numerous periodically spaced locations preempts strain-localization at one location and makes the In film highly stretchable by delaying rupture. Finally, the elastic-plastic mismatch-driven wrinkling of the In interconnect upon release from first loading cycle is utilized to delay the onset of plasticity and allow the interconnect to be stretched repeatedly up to 25% linear strain in subsequent cycles without a deterioration of its electrical performance.

  20. The effect of high density electric pulses on sintered aluminum 201AB silicon carbide MMC PM compacts during plastic deformation

    NASA Astrophysics Data System (ADS)

    Dariavach, Nader Guseinovich

    The effect of high-density electrical pulses on mechanical and structural properties of sintered aluminum SiC metal-matrix composites, fabricated by standard powder-metallurgy compaction and sintering, was investigated. Three types of phenomena where investigated during transverse rupture testing of the samples: a consolidation effect (increasing of the transverse rupture strength (TRS)), an electroplastic effect (decreasing of the flow stresses), and an increasing of the stress intensity factor by electric pulse application. It was observed, that an increase in the TRS strength of sintered powder metallurgy (PM) aluminum and aluminum metal matrix composite (MMC) compacts is a result of the electric pulse consolidation effect due to non-uniform temperature distribution around the grain boundaries. Three analytical models of the thermal effect of electric pulses on aluminum samples where considered: total temperature change of the sample due to a one electric pulse, one-dimensional steady state model and transient 2D thermal analysis of the temperature distribution around the grain boundary. The 2D transient analysis shows that the temperature rise in the grain boundary of a sintered PM aluminum sample due to an electric pulse can exceed the melting point. At the same time the temperature of the bulk material has an insignificant (<28°C) change. It was found that the electroplastic effect, due to electric pulse application, can account for up to a 40% load drop in aluminum MMC PM compacts. Reduction of flow stresses during plastic deformation could reduce the risk of structural damage, micro-cracks, SiC particle fracture and delamination of the aluminum MMC. These results may find practical application for manufacturing processes such as forging, extrusion, rolling, which involve plastic deformation. It was experimentally proven that a non-uniform temperature distribution around the crack could re-melt the crack tip and increase the strength of the damaged material

  1. The Interplay between Grain Size and Austenite Stability on Deformation Behavior of High Strength-High Ductility Combination Nanostructured Stainless Steel

    NASA Astrophysics Data System (ADS)

    Challa, Venkata Sai Ananth

    The concept of phase reversion involving severe cold deformation of metastable austenite to generate strain-induced martensite, followed by temperature-time annealing sequence, was used to obtain varying grain size from nanograined/ultrafine-grained (NG/UFG) to coarse-grained (CG) regime. This concept was used to obtain "high strength-high ductility" combination in nano/ultrafine-grained (NG/UFG) austenitic stainless steel. Using this concept, the objective of the study is to elucidate the dependence of grain size on deformation mechanisms and deformation-induced microstructural changes. The objective was accomplished by combining depth-sensing nanoindentation experiments conducted at various strain rates, and interrupted tensile testing at various strain and post-mortem analyses of deformed Fe-17Cr-7Ni (AISI 301LN) austenite alloy using transmission electron microscopy (TEM). In the high strength NG/UFG steel, deformation twinning contributed to excellent ductility, while in the low strength coarse-grained (CG) steel, ductility was also good, but due to strain-induced martensite, implying clear distinction and fundamental transition in the deformation behavior of NG/UFG and CG austenitic stainless steels. The study underscores that irrespective of the grain structure and operating deformation mechanisms (twinning versus strain-induced martensite), the generic nature of strain hardening is unaltered. In the NG/UFG structure, there was marked increase in stacking faults and twin density at high strain rates, and high strains. TWIP effect was observed in NG/UFG steel, whereas TRIP effect was evidenced in CG alloy. The observed change in the deformation mechanism with change in grain size is attributed to increased stability of austenite with decrease in grain size, and is explained in terms of austenite stability-strain energy relationship. The insights on the relationship between grain structure (and strength) and deformation mechanisms are envisaged to be important

  2. Relativistic Bound States in the Presence of Spherically Ring-Shaped q-DEFORMED Woods-Saxon Potential with Arbitrary l-STATES

    NASA Astrophysics Data System (ADS)

    Ikhdair, Sameer M.; Hamzavi, Majid; Rajabi, A. A.

    2013-03-01

    Approximate bound-state solutions of the Dirac equation with q-deformed Woods-Saxon (WS) plus a new generalized ring-shaped (RS) potential are obtained for any arbitrary l-state. The energy eigenvalue equation and corresponding two-component wave functions are calculated by solving the radial and angular wave equations within a shortcut of the Nikiforov-Uvarov (NU) method. The solutions of the radial and polar angular parts of the wave function are expressed in terms of the Jacobi polynomials. A new approximation being expressed in terms of the potential parameters is carried out to deal with the strong singular centrifugal potential term l(l+1)r-2. Under some limitations, we can obtain solution for the RS Hulthén potential and the standard usual spherical WS potential (q = 1).

  3. Kinetic Monte Carlo study of activated states and correlated shear-transformation-zone activity during the deformation of an amorphous metal

    NASA Astrophysics Data System (ADS)

    Homer, Eric R.; Rodney, David; Schuh, Christopher A.

    2010-02-01

    Shear transformation zone (STZ) dynamics simulations, which are based on the kinetic Monte Carlo algorithm, are used to model the mechanical response of amorphous metals and provide insight into the collective aspects of the microscopic events underlying deformation. The present analysis details the activated states of STZs in such a model, as well as the statistics of their activation and how these are affected by imposed conditions of stress and temperature. The analysis sheds light on the spatial and temporal correlations between the individual STZ activations that lead to different macroscopic modes of deformation. Three basic STZ correlation behaviors are observed: uncorrelated activity, nearest-neighbor correlation, and self-reactivating STZs. These three behaviors correspond well with the macroscopic deformation modes of homogeneous flow, inhomogeneous deformation, and elastic behavior, respectively. The effect of pre-existing stresses in the simulation cell is also studied and found to have a homogenizing effect on STZ correlations, suppressing the tendency for localization.

  4. Experimental Validation of Two-dimensional Finite Element Method for Simulating Constitutive Response of Polycrystals During High Temperature Plastic Deformation

    NASA Astrophysics Data System (ADS)

    Agarwal, Sumit; Briant, Clyde L.; Krajewski, Paul E.; Bower, Allan F.; Taleff, Eric M.

    2007-04-01

    A finite element method was recently designed to model the mechanisms that cause superplastic deformation (A.F. Bower and E. Wininger, A Two-Dimensional Finite Element Method for Simulating the Constitutive Response and Microstructure of Polycrystals during High-Temperature Plastic Deformation, J. Mech. Phys. Solids, 2004, 52, p 1289-1317). The computations idealize the solid as a collection of two-dimensional grains, separated by sharp grain boundaries. The grains may deform plastically by thermally activated dislocation motion, which is modeled using a conventional crystal plasticity law. The solid may also deform by sliding on the grain boundaries, or by stress-driven diffusion of atoms along grain boundaries. The governing equations are solved using a finite element method, which includes a front-tracking procedure to monitor the evolution of the grain boundaries and surfaces in the solid. The goal of this article is to validate these computations by systematically comparing numerical predictions to experimental measurements of the elevated-temperature response of aluminum alloy AA5083 (M.-A. Kulas, W.P. Green, E.M. Taleff, P.E. Krajewski, and T.R. McNelley, Deformation Mechanisms in Superplastic AA5083 materials. Metall. Mater. Trans. A, 2005, 36(5), p 1249-1261). The experimental work revealed that a transition occurs from grain-boundary sliding to dislocation (solute-drag) creep at approximately 0.001/s for temperatures between 425 and 500 °C. In addition, increasing the grain size from 7 to 10 μm decreased the transition to significantly lower strain rates. Predictions from the finite element method accurately predict the effect of grain size on the transition in deformation mechanisms.

  5. Influence of high deformation rate, brain region, transverse compression, and specimen size on rat brain shear stress morphology and magnitude.

    PubMed

    Haslach, Henry W; Gipple, Jenna M; Leahy, Lauren N

    2017-01-26

    An external mechanical insult to the brain, such as a blast, may create internal stress and deformation waves, which have shear and longitudinal components that can induce combined shear and compression of the brain tissue. To isolate the consequences of such interactions for the shear stress and to investigate the role of the extracellular fluid in the mechanical response, translational shear stretch at 10/s, 60/s, and 100/s translational shear rates under either 0% or 33% fixed transverse compression is applied without preconditioning to rat brain specimens. The specimens from the cerebrum, the cerebellum grey matter, and the brainstem white matter are nearly the full length of their respective regions. The translational shear stress response to translational shear deformation is characterized by the effect that each of four factors, high deformation rate, brain region, transverse compression, and specimen size, have on the shear stress magnitude averaged over ten specimens for each combination of factors. Increasing the deformation rate increases the magnitude of the shear stress at a given translational shear stretch, and as tested by ANOVAs so does applying transverse fixed compression of 33% of the thickness. The stress magnitude differs by the region that is the specimen source: cerebrum, cerebellum or brainstem. The magnitude of the shear stress response at a given deformation rate and stretch depends on the specimen length, called a specimen size effect. Surprisingly, under no compression a shorter length specimen requires more shear stress, but under 33% compression a shorter length specimen requires less shear stress, to meet a required shear deformation rate. The shear specimen size effect calls into question the applicability of the classical shear stress definition to hydrated soft biological tissue.

  6. The effect of high temperature deformation on the hot ductility of niobium-microalloyed steel

    NASA Astrophysics Data System (ADS)

    Zarandi, Faramarz Mh

    Low hot ductility at the straightening stage of the steel continuous casting process, where the surface temperature ranges from 600 to 1200°C, is associated with transverse cracking on the billet surface. This is attributed to various microalloying elements, which are essential for the mechanical characteristics of the final products. Thermomechanical processing is a new approach to alleviate this problem. In this work, two grades of Nb-containing steel, one modified with B, were examined. In order to simulate the key parameters of continuous casting, specimens were melted in situ and subjected to thermal conditions similar to that occurring in a continuous casting mill. They were also deformed at different stages of the thermal schedule. Finally, the hot ductility was evaluated at the end of the thermal schedule, corresponding to the straightening stage in continuous casting at which the hot ductility problem occurs in the continuous casting process. The results showed that the presence of B is noticeably beneficial to the hot ductility. Failure mode analysis was performed and the mechanism of fracture was elaborated. As well, the potential mechanisms under which B can improve the hot ductility were proposed. Deformation during solidification (i.e. in the liquid + solid two phase region) led to a significant loss of hot ductility in both steels. By contrast, deformation in the delta-ferrite region, after solidification, was either detrimental or beneficial depending on the deformation start temperature. The hot ductility was considerably improved in the steel without B when deformation was applied during the delta → gamma transformation. The effect of such deformation on the other steel grade was not significant. Examination of the microstructure revealed that such improvement is related to a grain refinement in austenite. Therefore, the effect of deformation parameters was studied in detail and the optimum condition leading to the greatest improvement in the

  7. Martensitic transformations and the evolution of the defect microstructure of metastable austenitic steel during severe plastic deformation by high-pressure torsion

    NASA Astrophysics Data System (ADS)

    Litovchenko, I. Yu.; Tyumentsev, A. N.; Akkuzin, S. A.; Naiden, E. P.; Korznikov, A. V.

    2016-08-01

    It has been shown that, in metastable austenitic Fe-18Cr-10Ni-Ti steel, under conditions of torsion under pressure, local reversible (forward plus reverse) (γ → α' → γ) martensitic transformations can occur, which are one of the mechanisms of the formation of nanostructured states. An increase in the rotation rate, which leads to an increase in the deformation temperature, stimulates the reverse (α' → γ) transformation. The evolution of the structural and phase states is represented as the following sequence: (1) mechanical twinning; (2) nucleation of martensitic plates in the microtwinned structure of the austenite with the formation of two-phase (γ + α') structures, packet α' martensite, and structural states with a high curvature of the crystal lattice; (3) reverse (α' → γ)-transformations; and (4) the fragmentation of nanosized crystals via the formation of a nanotwinned structure in the austenite and of a nanoscale banded structure of the ɛ martensite in the α' martensite.

  8. Direct experimental evidence for a multiparticle-hole ground state configuration of deformed 33Mg

    NASA Astrophysics Data System (ADS)

    Datta, Ushasi; Rahaman, A.; Aumann, T.; Beceiro-Novo, S.; Boretzky, K.; Caesar, C.; Carlson, B. V.; Catford, W. N.; Chakraborty, S.; Chartier, M.; Cortina-Gil, D.; de Angelis, G.; Diaz Fernandez, P.; Emling, H.; Ershova, O.; Fraile, L. M.; Geissel, H.; Gonzalez-Diaz, D.; Jonson, B.; Johansson, H.; Kalantar-Nayestanaki, N.; Kröll, T.; Krücken, R.; Kurcewicz, J.; Langer, C.; Le Bleis, T.; Leifels, Y.; Marganiec, J.; Münzenberg, G.; Najafi, M. A.; Nilsson, T.; Nociforo, C.; Panin, V.; Paschalis, S.; Plag, R.; Reifarth, R.; Ricciardi, V.; Rossi, D.; Scheit, H.; Scheidenberger, C.; Simon, H.; Taylor, J. T.; Togano, Y.; Typel, S.; Volkov, V.; Wagner, A.; Wamers, F.; Weick, H.; Weigand, M.; Winfield, J. S.; Yakorev, D.; Zoric, M.

    2016-09-01

    The first direct experimental evidence of a multiparticle-hole ground state configuration of the neutron-rich 33Mg isotope has been obtained via intermediate energy (400 A MeV) Coulomb dissociation measurement. The major part ˜(70 ±13 )% of the cross section is observed to populate the excited states of 32Mg after the Coulomb breakup of 33Mg. The shapes of the differential Coulomb dissociation cross sections in coincidence with different core excited states favor that the valence neutron occupies both the s1 /2 and p3 /2 orbitals. These experimental findings suggest a significant reduction and merging of s d -p f shell gaps at N ˜20 and 28. The ground state configuration of 33Mg is predominantly a combination of 32Mg(3.0 ,3.5 MeV ;2-,1-) ⨂νs1/2 , 32Mg(2.5 MeV ;2+) ⨂νp3/2 , and 32Mg(0 ;0+) ⨂νp3/2 . The experimentally obtained quantitative spectroscopic information for the valence neutron occupation of the s and p orbitals, coupled with different core states, is in agreement with Monte Carlo shell model (MCSM) calculation using 3 MeV as the shell gap at N =20 .

  9. Microstructure and nanohardness distribution in a polycrystalline Zn deformed by high strain rate impact

    SciTech Connect

    Dirras, G.; Ouarem, A.; Couque, H.; Gubicza, J.; Szommer, P.; Brinza, O.

    2011-05-15

    Polycrystalline Zn with an average grain size of about 300 {mu}m was deformed by direct impact Hopkinson pressure bar at a velocity of 29 m/s. An inhomogeneous grain structure was found consisting of a center region having large average grain size of 20 {mu}m surrounded by a fine-grained rim with an average grain size of 6 {mu}m. Transmission electron microscopy investigations showed a significant dislocation density in the large-grained area while in the fine-grained rim the dislocation density was negligible. Most probably, the higher strain yielded recrystallization in the outer ring while in the center only recovery occurred. The hardening effect of dislocations overwhelms the smaller grain size strengthening in the center part resulting in higher nanohardness in this region than in the outer ring. - Graphical Abstract: (a): EBSD micrograph showing the initial microstructure of polycrystalline Zn that was subsequently submitted to high strain rate impact. (b): an inhomogeneous grain size refinement was obtained which consists of a central coarse-grained area, surrounded by a fine-grained recrystallized rim. The black arrow points to the disc center. Research Highlights: {yields} A polycrystalline Zn specimen was submitted to high strain rate impact loading. {yields} Inhomogeneous grain refinement occurred due to strain gradient in impacted sample. {yields} A fine-grained recrystallized rim surrounded the coarse-grained center of specimen. {yields} The coarse-grained center exhibited higher hardness than the fine-grained rim. {yields} The higher hardness of the center was caused by the higher dislocation density.

  10. The emergence of deformation and rotational states in the many-nucleon quantum theory of nuclei

    NASA Astrophysics Data System (ADS)

    Rowe, D. J.

    2016-02-01

    The many-nucleon quantum mechanics of a nucleus is infinite-dimensional and, although simply defined, it has the potential for unlimited complexity. Nevertheless, the low-energy states of heavy open-shell nuclei exhibit properties that are remarkably well described by simple collective models. This paper examines this emergent simplicity from a perspective that closely parallels the emergence of shell structure in the Mayer-Jensen model. The result is an expression of the many-nucleon Hilbert space of a nucleus as an energy-ordered sum of subspaces each of which carries a microscopic version of the Bohr-Mottelson unified model. Each of the subspaces is characterized by nuclear states with a common intrinsic shape defined by its quadrupole moments. An emergence of simplicity and shape-coexistence in nuclei is then explained if it can be demonstrated that there is a relatively small and coherent mixing of the states of different collective subspaces.

  11. High-resolution microdiffraction study of notch-tip deformation in Mo single crystals using x-ray synchrotron radiation

    SciTech Connect

    Ice, G.; Habenschuss, A.; Bilello, J.C.; Rebonato, R.

    1989-12-31

    A new technique is presented for the determination of strain fields in single crystals, based on the simultaneous record