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Sample records for macroscopic deformation behavior

  1. Macroscopic inhomogeneous deformation behavior arising in single crystal Ni-Mn-Ga foils under tensile loading

    Science.gov (United States)

    Murasawa, Go; Yeduru, Srinivasa R.; Kohl, Manfred

    2016-12-01

    This study investigated macroscopic inhomogeneous deformation occurring in single-crystal Ni-Mn-Ga foils under uniaxial tensile loading. Two types of single-crystal Ni-Mn-Ga foil samples were examined as-received and after thermo-mechanical training. Local strain and the strain field were measured under tensile loading using laser speckle and digital image correlation. The as-received sample showed a strongly inhomogeneous strain field with intermittence under progressive deformation, but the trained sample result showed strain field homogeneity throughout the specimen surface. The as-received sample is a mainly polycrystalline-like state composed of the domain structure. The sample contains many domain boundaries and large domain structures in the body. Its structure would cause large local strain band nucleation with intermittence. However, the trained one is an ideal single-crystalline state with a transformation preferential orientation of variants after almost all domain boundary and large domain structures vanish during thermo-mechanical training. As a result, macroscopic homogeneous deformation occurs on the trained sample surface during deformation.

  2. Achieving large macroscopic compressive plastic deformation and work-hardening-like behavior in a monolithic bulk metallic glass by tailoring stress distribution

    Science.gov (United States)

    Chen, L. Y.; Ge, Q.; Qu, S.; Jiang, Q. K.; Nie, X. P.; Jiang, J. Z.

    2008-05-01

    The limited plastic deformation and lack of work hardening seriously restrict the applications of bulk metallic glasses (BMGs). Here, large macroscopic compressive plastic deformation (over 15%) and work-hardening-like behavior were achieved in a monolithic BMG through tailoring loading stress distribution experimentally. Numerical analysis was also carried out to investigate the stress distribution under the same mechanical condition. It is shown that loading induced stress gradient is responsible for the achievement mentioned above.

  3. Stimuli-deformable graphene materials: from nanosheet to macroscopic assembly

    Directory of Open Access Journals (Sweden)

    Fei Zhao

    2016-04-01

    Full Text Available Stimulus-induced deformation (SID of graphene-based materials has triggered rapidly increasing research interest due to the spontaneous response to external stimulations, which enables precise configurational regulation of single graphene nanosheets (GNSs through control over the environmental conditions. While the micro-strain of GNS is barely visible, the deformation of graphene-based macroscopic assemblies (GMAs is remarkable, thereby presenting significant potential for future application in smart devices. This review presents the current progress of SID of graphene in the manner of nanosheets and macroscopic assemblies in both the experimental and theoretical fronts, and summarizes recent advancements of SID of graphene for applications in smart systems.

  4. Localization of deformation and loss of macroscopic ellipticity in microstructured solids

    Science.gov (United States)

    Santisi d'Avila, M. P.; Triantafyllidis, N.; Wen, G.

    2016-12-01

    Localization of deformation, a precursor to failure in solids, is a crucial and hence widely studied problem in solid mechanics. The continuum modeling approach of this phenomenon studies conditions on the constitutive laws leading to the loss of ellipticity in the governing equations, a property that allows for discontinuous equilibrium solutions. Micro-mechanics models and nonlinear homogenization theories help us understand the origins of this behavior and it is thought that a loss of macroscopic (homogenized) ellipticity results in localized deformation patterns. Although this is the case in many engineering applications, it raises an interesting question: is there always a localized deformation pattern appearing in solids losing macroscopic ellipticity when loaded past their critical state? In the interest of relative simplicity and analytical tractability, the present work answers this question in the restrictive framework of a layered, nonlinear (hyperelastic) solid in plane strain and more specifically under axial compression along the lamination direction. The key to the answer is found in the homogenized post-bifurcated solution of the problem, which for certain materials is supercritical (increasing force and displacement), leading to post-bifurcated equilibrium paths in these composites that show no localization of deformation for macroscopic strain well above the one corresponding to loss of ellipticity.

  5. Time-dependent mechanical behavior of human amnion: macroscopic and microscopic characterization.

    Science.gov (United States)

    Mauri, Arabella; Perrini, Michela; Ehret, Alexander E; De Focatiis, Davide S A; Mazza, Edoardo

    2015-01-01

    Characterizing the mechanical response of the human amnion is essential to understand and to eventually prevent premature rupture of fetal membranes. In this study, a large set of macroscopic and microscopic mechanical tests have been carried out on fresh unfixed amnion to gain insight into the time-dependent material response and the underlying mechanisms. Creep and relaxation responses of amnion were characterized in macroscopic uniaxial tension, biaxial tension and inflation configurations. For the first time, these experiments were complemented by microstructural information from nonlinear laser scanning microscopy performed during in situ uniaxial relaxation tests. The amnion showed large tension reduction during relaxation and small inelastic strain accumulation in creep. The short-term relaxation response was related to a concomitant in-plane and out-of-plane contraction, and was dependent on the testing configuration. The microscopic investigation revealed a large volume reduction at the beginning, but no change of volume was measured long-term during relaxation. Tension-strain curves normalized with respect to the maximum strain were highly repeatable in all configurations and allowed the quantification of corresponding characteristic parameters. The present data indicate that dissipative behavior of human amnion is related to two mechanisms: (i) volume reduction due to water outflow (up to ∼20 s) and (ii) long-term dissipative behavior without macroscopic deformation and no systematic global reorientation of collagen fibers.

  6. Macroscopic Behavior of Nematics with D2d Symmetry

    Science.gov (United States)

    Pleiner, Harald; Brand, Helmut R.

    2010-03-01

    We discuss the symmetry properties and the macroscopic behavior of a nematic liquid crystal phase with D2d symmetry. Such a phase is a prime candidate for nematic phases made from banana-shaped molecules where the usual quadrupolar order coexists with octupolar (tetrahedratic) order. The resulting nematic phase is non-polar. While this phase could resemble the classic D∞h nematic in the polarizing microscope, it has many static as well as reversible and irreversible properties unknown to non-polar nematics without octupolar order. In particular, there is a linear gradient term in the free energy that selects parity leading to ambidextrously helical ground states when the molecules are achiral. In addition, there are static and irreversible coupling terms of a type only met otherwise in macroscopically chiral liquid crystals, e.g. the ambidextrous analogues of Lehmann-type effects known from cholesteric liquid crystals. Finally, we discuss certain nonlinear aspects of the dynamics related to the non-commutativity of three-dimensional finite rotations as well as other structural nonlinear hydrodynamic effects.

  7. Macroscopic behavior and microscopic magnetic properties of nanocarbon

    Energy Technology Data Exchange (ETDEWEB)

    Lähderanta, E., E-mail: Erkki.Lahderanta@lut.fi [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Ryzhov, V.A. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Coppice, Gatchina, Leningrad province 188300 (Russian Federation); Lashkul, A.V. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Galimov, D.M. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); South Ural State University, 454080 Chelyabinsk (Russian Federation); Titkov, A.N. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); A. F. Ioffe Physico-Technical Institute, 194021 St. Petersburg (Russian Federation); Matveev, V.V. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Saint-Petersburg State University, Saint-Petersburg 198504 (Russian Federation); Mokeev, M.V. [Institute of Macromolecular Compounds, Russian Academy of Sciences, St. Petersburg (Russian Federation); Kurbakov, A.I. [Petersburg Nuclear Physics Institute, NRC “Kurchatov Institute”, Orlova Coppice, Gatchina, Leningrad province 188300 (Russian Federation); Lisunov, K.G. [Lappeenranta University of Technology, PO Box 20, FIN-53851 Lappeenranta (Finland); Institute of Applied Physics ASM, Academiei Str., 5, MD 2028 Kishinev (Moldova, Republic of)

    2015-06-01

    Here are presented investigations of powder and glass-like samples containing carbon nanoparticles, not intentionally doped and doped with Ag, Au and Co. The neutron diffraction study reveals an amorphous structure of the samples doped with Au and Co, as well as the magnetic scattering due to a long-range FM order in the Co-doped sample. The composition and molecular structure of the sample doped with Au is clarified with the NMR investigations. The temperature dependence of the magnetization, M (T), exhibits large irreversibility in low fields of B=1–7 mT. M (B) saturates already above 2 T at high temperatures, but deviates from the saturation behavior below ~50 (150 K). Magnetic hysteresis is observed already at 300 K and exhibits a power-law temperature decay of the coercive field, B{sub c} (T). The macroscopic behavior above is typical of an assembly of partially blocked magnetic nanoparticles. The values of the saturation magnetization, M{sub s}, and the blocking temperature, T{sub b}, are obtained as well. However, the hysteresis loop in the Co-doped sample differs from that in other samples, and the values of B{sub c} and M{sub s} are noticeably increased. - Highlights: • We have investigated powder and glassy samples with carbon nanoparticles. • They include an undoped sample and those doped with Ag, Au and Co. • Neutron diffraction study reveals amorphous structure of Au- and Co-doped samples. • Composition and molecular structure of Au-doped sample was investigated with NMR. • Magnetic behavior is typical of an assembly of partially blocked magnetic nanoparticles.

  8. Macroscopic and Microstructural Aspects of the Transformation Behavior in a Polycrystalline NiTi Shape Memory Alloy

    Science.gov (United States)

    Benafan, Othmane; Noebe, Ronald D.; Padula, Santo A., II; Lerch, Bradley A.; Bigelow, Glen S.; Gaydosh, Darrell J.; Garg, Anita; An, Ke; Vaidyanathan, Raj

    2013-01-01

    The mechanical and microstructural behavior of a polycrystalline Ni(49.9)Ti(50.1) (at.%) shape memory alloy was investigated as a function of temperature around the transformation regime. The bulk macroscopic responses, measured using ex situ tensile deformation and impulse excitation tests, were compared to the microstructural evolution captured using in situ neutron diffraction. The onset stress for inelastic deformation and dynamic Young's modulus were found to decrease with temperature, in the martensite regime, reaching a significant minimum at approximately 80 C followed by an increase in both properties, attributed to the martensite to austenite transformation. The initial decrease in material compliance during heating affected the ease with which martensite reorientation and detwinning could occur, ultimately impacting the stress for inelastic deformation prior to the start of the reverse transformation.

  9. Deformation Behavior of Nanoporous Metals

    Energy Technology Data Exchange (ETDEWEB)

    Biener, J; Hodge, A M; Hamza, A V

    2007-11-28

    of free surfaces can no longer be neglected. As the material becomes more and more constraint by the presence of free surfaces, length scale effects on plasticity become more and more important and bulk properties can no longer be used to describe the material properties. Even the elastic properties may be affected as the reduced coordination of surface atoms and the concomitant redistribution of electrons may soften or stiffen the material. If, and to what extend, such length scale effects control the mechanical behavior of nanoporous materials depends strongly on the material and the characteristic length scale associated with its plastic deformation. For example, ductile materials such as metals which deform via dislocation-mediated processes can be expected to exhibit pronounced length scale effects in the sub-micron regime where free surfaces start to constrain efficient dislocation multiplication. In this chapter we will limit our discussion to our own area of expertise which is the mechanical behavior of nanoporous open-cell gold foams as a typical example of nanoporous metal foams. Throughout this chapter we will review our current understanding of the mechanical properties of nanoporous open-cell foams including both experimental and theoretical studies.

  10. Deformation behavior of open-cell stainless steel foams

    Energy Technology Data Exchange (ETDEWEB)

    Kaya, A.C., E-mail: a.kaya@campus.tu-berlin.de; Fleck, C.

    2014-10-06

    This study presents the deformation and cell collapse behavior of open-cell stainless steel foams. 316L stainless-steel open-cell foams with two porosities (30 and 45 pores per inch, ppi) were produced with the pressureless powder metallurgical method, and tested in quasi-static compression. As a result of the manufacturing technique, 316L stainless steel open-cell foams have a high amount of microporosity. The deformation behavior was investigated on a macroscopic scale by digital image correlation (DIC) evaluation of light micrographs and on the microscopic scale by in situ loading of cells in the scanning electron microscope. The deformation behavior of the metal foams was highly affected by microstructural features, such as closed pores and their distribution throughout the foam specimen. Moreover, the closed pores made a contribution to the plateau stress of the foams through cell face stretching. Strut buckling and bending are the dominant mechanisms in cell collapse. Although there are edge defects on the struts, the struts have an enormous plastic deformation capability. The cell size of the steel foams had no significant effect on the mechanical properties. Due to the inhomogeneities in the microstructure, the measured plateau stresses of the foams showed about 20% scatter at the same relative density.

  11. Cyclic Shearing Deformation Behavior of Saturated Clays

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The apparatus for static and dynamic universal triaxial and torsional shear soil testing is employed to perform stress-controlled cyclic single-direction torsional shear tests and two-direction coupled shear tests under unconsolidated-undrained conditions. Through a series of tests on saturated clay, the effects of initial shear stress and stress reversal on the clay's strain-stress behavior are examined, and the behavior of pore water pressure is studied. The experimental results indicate that the patterns of stress-strain relations are distinctly influenced by the initial shear stress in the cyclic single-direction shear tests. When the initial shear stress is large and no stress reversal occurs, the predominant deformation behavior is characterized by an accumulative effect. When the initial shear stress is zero and symmetrical cyclic stress occurs, the predominant deformation behavior is characterized by a cyclic effect. The pore water pressure fluctuates around the confining pressure with the increase of cycle number. It seems that the fluctuating amplitude increases with the increase of the cyclic stress. But a buildup of pore water pressure does not occur. The deformations of clay samples under the complex initial and the cyclic coupled stress conditions include the normal deviatoric deformation and horizontal shear deformation, the average deformation and cyclic deformation. A general strain failure criterion taking into account these deformations is recommended and is proved more stable and suitable compared to the strain failure criteria currently used.

  12. Deformation behavior of Fe-based bulk metallic glass during nanoindentation

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Fe-based bulk metallic glasses (BMGs) normally exhibit super high strength but significant brittleness at ambient temperature. Therefore,it is difficult to investigate the plastic deformation behavior and mechanism in these alloys through conven-tional tensile and compressive tests due to lack of distinct macroscopic plastic strain. In this work,the deformation behavior of Fe52Cr15Mo9Er3C15B6 BMG was in-vestigated through instrumented nanoindentation and uniaxial compressive tests. The results show that serrated flow,the typical plastic deformation feature of BMGs,could not be found in as-cast and partially crystallized samples during nanoinden-tation. In addition,the deformation behavior and mechanical properties of the alloy are insensitive to the applied loading rate. The mechanism for the appearance of the peculiar deformation behavior in the Fe-based BMG is discussed in terms of the temporal and spatial characteristics of shear banding during nanoindentation.

  13. Deformation behavior of Fe-based bulk metallic glass during nanoindentation

    Institute of Scientific and Technical Information of China (English)

    LI Lei; LIU Yuan; ZHANG TaiHua; GU JianSheng; WEI BingChen

    2008-01-01

    Fe-based bulk metallic glasses (BMGs) normally exhibit super high strength but significant brittleness at ambient temperature. Therefore, it is difficult to investigate the plastic deformation behavior and mechanism in these alloys through conven-tional tensile and compressive tests due to lack of distinct macroscopic plastic strain. In this work, the deformation behavior of Fe52Cr15Mo9Er3C15B6 BMG was in-vestigated through instrumented nanoindentation and uniaxial compressive tests. The results show that serrated flow, the typical plastic deformation feature of BMGs, could not be found in as-cast and partially crystallized samples during nanoinden-tation. In addition, the deformation behavior and mechanical properties of the alloy are insensitive to the applied loading rate. The mechanism for the appearance of the peculiar deformation behavior in the Fe-based BMG is discussed in terms of the temporal and spatial characteristics of shear banding during nanoindentation.

  14. Hot deformation behavior of FGH96 superalloys

    Institute of Scientific and Technical Information of China (English)

    Jiantao Liu; Guoquan Liu; Benfu Hu; Yuepeng Song; Ziran Qin; Yiwen Zhang

    2006-01-01

    The hot deformation behavior of FGH96 superalloys at 1070-1170℃ and 5×10-4-2×10-1 s-1 were investigated by means of the isothermal compression tests at a Gleeble-1500 thermal mechanical simulator. The results show that dynamic recovery acts as the main softening mechanism below 2×10-3 s-1, whereas dynamic recrystallization acts as the main softening mechanism above 2×10-3 s-1during deformation; the temperature increase caused by the deformation and the corresponding softening stress is negligible; the thermal-mechanical constitutive model to describe the hot deformation behavior is given, and the value of the apparent deformation activation energy (Qdef) is determined to be 354.93 kJ/mol.

  15. Electromagnetic emission in the development of macroscopically unstable plastic deformation of a metal

    Science.gov (United States)

    Shibkov, A. A.; Titov, S. A.; Zheltov, M. A.; Gasanov, M. F.; Zolotov, A. E.; Proskuryakov, K. A.; Zhigachev, A. O.

    2016-01-01

    Electromagnetic emission accompanying the serrated deformation of the aluminum‒magnesium alloy Al-6Mg has been revealed and studied experimentally. By means of high-speed video recording and a complex of methods for measuring the strain, load, and electric potential, it has been found that there is a relation between the electromagnetic emission signals and the dynamics of deformation bands. Possible mechanisms of the generation of electromagnetic signals have been discussed.

  16. Regularities of Macroscopic Localization of Plastic Deformation in the Stretching of a Low-Carbon Steel

    Science.gov (United States)

    Barannikova, S. A.; Kosinov, D. A.; Nadezhkin, M. V.; Lunev, A. G.; Gorbatenko, V. V.; Zuev, L. B.; Gromov, V. E.

    2014-07-01

    The special features of plastic deformation localization in the stretching of polycrystals of low-carbon steel 08 ss after hot rolling and electrolytic saturation with hydrogen are investigated. The main types and parameters of plastic flow localization in different stages of strain hardening are determined by the method of double-exposure speckle photography.

  17. Large deformation behavior of fat crystal networks

    NARCIS (Netherlands)

    Kloek, W.; Vliet, van T.; Walstra, P.

    2005-01-01

    Compression and wire-cutting experiments on dispersions of fully hydrogenated palm oil in sunflower oil with varying fraction solid fat were carried out to establish which parameters are important for the large deformation behavior of fat crystal networks. Compression experiments showed that the app

  18. Modeling the macroscopic behavior of two-phase nonlinear composites by infinite-rank laminates

    Science.gov (United States)

    Idiart, Martín I.

    A new approach is proposed for estimating the macroscopic behavior of two-phase nonlinear composites with random, particulate microstructures. The central idea is to model composites by sequentially laminated constructions of infinite rank whose macroscopic behavior can be determined exactly. The resulting estimates incorporate microstructural information up to the two-point correlation functions, and require the solution to a Hamilton-Jacobi equation with the inclusion concentration and the macroscopic fields playing the role of 'time' and 'spatial' variables, respectively. Because they are realizable, by construction, these estimates are guaranteed to be convex, to satisfy all pertinent bounds, to exhibit no duality gap, and to be exact to second order in the heterogeneity contrast. Sample results are provided for two- and three-dimensional power-law composites, and are compared with other homogenization estimates, as well as with numerical simulations available from the literature. The estimates are found to give physically sensible predictions for all the cases considered, even for extreme values of the nonlinearity and heterogeneity contrast. Interestingly, in the case of isotropic porous materials under hydrostatic loadings, the estimates agree exactly with standard Gurson-type models for viscoplastic porous media.

  19. Alloy-dependent deformation behavior of highly ductile nanocrystalline AuCu thin films

    Energy Technology Data Exchange (ETDEWEB)

    Lohmiller, Jochen [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, 76021 Karlsruhe (Germany); Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); Spolenak, Ralph [Laboratory for Nanometallurgy, Department of Materials, ETH Zurich, Wolfgang-Pauli-Str. 10, 8093 Zurich (Switzerland); Gruber, Patric A., E-mail: patric.gruber@kit.edu [Karlsruhe Institute of Technology, Institute for Applied Materials, P.O. Box 3640, 76021 Karlsruhe (Germany)

    2014-02-10

    Nanocrystalline thin films on compliant substrates become increasingly important for the development of flexible electronic devices. In this study, nanocrystalline AuCu thin films on polyimide substrate were tested in tension while using a synchrotron-based in situ testing technique. Analysis of X-ray diffraction profiles allowed identifying the underlying deformation mechanisms. Initially, elastic and microplastic deformation is observed, followed by dislocation-mediated shear band formation, and eventually macroscopic crack formation. Particularly the influence of alloy composition, heat-treatment, and test temperature were investigated. Generally, a highly ductile behavior is observed. However, high Cu concentrations, annealing, and/or large plastic strains lead to localized deformation and hence reduced ductility. On the other hand, enhanced test temperature allows for a delocalized deformation and extended ductility.

  20. Hot Deformation Behavior of 2124 Al Alloy

    Institute of Scientific and Technical Information of China (English)

    S.Ramanathan; R.Karthikeyan; V.Deepak Kumar; G.Ganesan

    2006-01-01

    The mechanical behavior of 2124 Al alloy produced by powder metallurgy was investigated with compression test at different temperatures and strain rates. The tests were performed in the temperature range of 300℃~500℃ and at strain rates from 0.001 s-1 to 1.0 s-1. The compression flow curves exhibited an initial sharp increase with strain, followed by monotonous hardening. The maximum stress decreased with decreasing strain rate and increasing temperature. The hot deformation characteristics of the material were studied using processing maps. The domain of safety and unsafe regime were identified and validated through microstructural examination.

  1. Critical behavior of a two-dimensional complex fluid: Macroscopic and mesoscopic views

    Science.gov (United States)

    Choudhuri, Madhumita; Datta, Alokmay

    2016-04-01

    Liquid disordered (Ld) to liquid ordered (Lo) phase transition in myristic acid [MyA, CH3(CH2) 12COOH ] Langmuir monolayers was studied macroscopically as well as mesoscopically to locate the critical point. Macroscopically, isotherms of the monolayer were obtained across the 20 ∘C-38 ∘Ctemperature (T ) range and the critical point was estimated, primarily from the vanishing of the order parameter, at ≈38 ∘C. Mesoscopically, domain morphology in the Ld-Lo coexistence regime was imaged using the technique of Brewster angle microscopy (BAM) as a function of T and the corresponding power spectral density function (PSDF) obtained. Monolayer morphology passed from stable circular domains and a sharp peak in PSDF to stable dendritic domains and a divergence of the correlation length as the critical point was approached from below. The critical point was found to be consistent at ≈38 ∘Cfrom both isotherm and BAM results. In the critical regime the scaling behavior of the transition followed the two-dimensional Ising model. Additionally, we obtained a precritical regime, over a temperature range of ≈8 ∘C below Tc, characterized by fluctuations in the order parameter at the macroscopic scale and at the mesoscopic scale characterized by unstable domains of fingering or dendritic morphology as well as proliferation of a large number of small sized domains, multiple peaks in the power spectra, and a corresponding fluctuation in the peak q values with T . Further, while comparing temperature studies on an ensemble of MyA monolayers with those on a single monolayer, the system was found to be not strictly ergodic in that the ensemble development did not strictly match with the time development in the system. In particular, the critical temperature was found to be lowered in the latter. These results clearly show that the critical behavior in fatty acid monolayer phase transitions have features of both complex and nonequilibrium systems.

  2. Healing behavior of preexisting hydrogen micropores in aluminum alloys during plastic deformation

    Energy Technology Data Exchange (ETDEWEB)

    Toda, H., E-mail: toda@pse.tut.ac.jp [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Minami, K. [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Koyama, K.; Ichitani, K. [Furukawa-Sky Aluminum Corp., 1351, Uwanodai, Fukaya, Saitama 366-8511 (Japan); Kobayashi, M. [Department of Production Systems Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Uesugi, K.; Suzuki, Y. [Japan Synchrotron Radiation Research Institute, Mikazuki-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2009-09-15

    Synchrotron X-ray microtomography was used to observe the shrinkage and annihilation behaviors of hydrogen micropores in three dimensions during hot and cold plastic deformation of an Al-Mg alloy. Whether complete healing of micropores is achieved after plastic deformation was examined by exposing the material to a high temperature after plastic deformation. Although micropores generally show a pattern of shrinking and closing, closer inspection of a single specimen revealed a variety of geometrically variable behaviors. It is noteworthy that some of the micropores are reinitiated in positions identical to those before their annihilation, even after an 8-22% macroscopic strain has been further applied after annihilation. We attribute local variations such as these to significant local strain variation, which we measured in a series of tomographic volumes by tracking the microstructural features.

  3. Deformation, fatigue and fracture behavior of two cast anisotropic superalloys

    Science.gov (United States)

    Milligan, Walter W.; Huron, Eric S.; Antolovich, Stephen D.

    1987-01-01

    Tensile and low cycle fatigue (LCF) tests were conducted on two cast anisotropic superalloys. The effects of temperature, strain rate and stress range were investigated. Deformation behavior was extensively characterized and modeled. LCF and fracture behavior were studied and correlated with deformation behavior.

  4. A robust macroscopic model for normal-shear coupling, asymmetric and anisotropic behaviors of polycrystalline SMAs

    Science.gov (United States)

    Bodaghi, M.; Damanpack, A. R.; Liao, W. H.

    2016-07-01

    The aim of this article is to develop a robust macroscopic bi-axial model to capture self-accommodation, martensitic transformation/orientation/reorientation, normal-shear deformation coupling and asymmetric/anisotropic strain generation in polycrystalline shape memory alloys. By considering the volume fraction of martensite and its preferred direction as scalar and directional internal variables, constitutive relations are derived to describe basic mechanisms of accommodation, transformation and orientation/reorientation of martensite variants. A new definition is introduced for maximum recoverable strain, which allows the model to capture the effects of tension-compression asymmetry and transformation anisotropy. Furthermore, the coupling effects between normal and shear deformation modes are considered by merging inelastic strain components together. By introducing a calibration approach, material and kinetic parameters of the model are recast in terms of common quantities that characterize a uniaxial phase kinetic diagram. The solution algorithm of the model is presented based on an elastic-predictor inelastic-corrector return mapping process. In order to explore and demonstrate capabilities of the proposed model, theoretical predictions are first compared with existing experimental results on uniaxial tension, compression, torsion and combined tension-torsion tests. Afterwards, experimental results of uniaxial tension, compression, pure bending and buckling tests on {{NiTi}} rods and tubes are replicated by implementing a finite element method along with the Newton-Raphson and Riks techniques to trace non-linear equilibrium path. A good qualitative and quantitative correlation is observed between numerical and experimental results, which verifies the accuracy of the model and the solution procedure.

  5. Thermal image analysis of plastic deformation and fracture behavior by a thermo-video measurement system

    Science.gov (United States)

    Ohbuchi, Yoshifumi; Sakamoto, Hidetoshi; Nagatomo, Nobuaki

    2016-12-01

    The visualization of the plastic region and the measurement of its size are necessary and indispensable to evaluate the deformation and fracture behavior of a material. In order to evaluate the plastic deformation and fracture behavior in a structural member with some flaws, the authors paid attention to the surface temperature which is generated by plastic strain energy. The visualization of the plastic deformation was developed by analyzing the relationship between the extension of the plastic deformation range and the surface temperature distribution, which was obtained by an infrared thermo-video system. Furthermore, FEM elasto-plastic analysis was carried out with the experiment, and the effectiveness of this non-contact measurement system of the plastic deformation and fracture process by a thermography system was discussed. The evaluation method using an infrared imaging device proposed in this research has a feature which does not exist in the current evaluation method, i.e. the heat distribution on the surface of the material has been measured widely by noncontact at 2D at high speed. The new measuring technique proposed here can measure the macroscopic plastic deformation distribution on the material surface widely and precisely as a 2D image, and at high speed, by calculation from the heat generation and the heat propagation distribution.

  6. Deformation behavior and microstructure evolution of wrought magnesium alloys

    Science.gov (United States)

    Wang, Shouren; Song, Linghui; Kang, Sukbong; Cho, Jaehyung; Wang, Yingzi

    2013-05-01

    There are many researches on the deformation behavior of wrought magnesium alloys, such as AZ31, AZ80, AZ91, and ZK60 magnesium alloys at different temperatures and strain rates, but few of them focuses on the deformation behavior of AZ41M and ZK60M alloys, especially under the twin-roll casting (TRC) state. Meanwhile, the existing researches only focus on the grain refinement law of the magnesium alloys under deformation conditions, the deformation mechanism has not been revealed yet. The hot compression behavior of AZ41M and ZK60M magnesium alloys under the temperature and strain rate ranges of 250-400 °C and 0.001-1 s-1 are studied by thermal simulation methods using Gleeble 1500 machine and virtual simulation using finite element analysis software. Simulation results show that sine hyperbolic law is the most suitable flow stress model for wider deformation conditions. The most reasonable selected deformation conditions of ZK60M alloy is 350 °C/0.1 s-1 for TRC and 350 °C/1 s-1 for conventional casting (CC), while AZ41M alloy is 300 °C/0.01 s-1 for TRC and 350 °C/0.1 s-1 for CC. Deformation behavior and dynamic recrystallization (DRX) mechanism of them are analyzed at the same deformation conditions. The microstructures of AZ41M and ZK60M alloys are observed at different deformed conditions by optical microscopy (OM) and electron back scatter diffraction (EBSD) and it reveals the flow behavior and deformation mechanism of them. Working harden and work soften contribute to the activation of basal, non-basal slip systems which promote DRX. The proposed research reveals the deformation behavior and mechanism of the AZ41M and ZK 60M magnesium alloys and concludes their optimized deformation parameters and processes and provides a theory basis for their manufacturing and application.

  7. Effects of macroscopic bulk defects on the damping behaviors of materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A large number of macroscopic pores or graphite particulates wereintroduced into commercially pure Al and ZA27 alloy by infiltration proces s to comparatively study the influence of macroscopic defects on the damping beh aviors of the materials. The mean diameter of the bulk defects is (1.0±0.5) mm, and the volume fractions of pores and graphite particulates are in the range of 50%—75% and 19%—94%, separately. It is shown that addition of a number of por es or graphite particulates can significantly improve the damping of commerciall y pure Al, due to the comprehensive effects of the macroscopic and microscopic d efects. However, the pores have little effect on the damping capacity of high da mping ZA27 alloy, and graphite particulates make the high temperature internal f riction peak decrease. It is considered that graphite particulates may repress t he intrinsic damping mechanism of ZA27 alloy.

  8. The effect of interlayer adhesion on the mechanical behaviors of macroscopic graphene oxide papers.

    Science.gov (United States)

    Gao, Yun; Liu, Lu-Qi; Zu, Sheng-Zhen; Peng, Ke; Zhou, Ding; Han, Bao-Hang; Zhang, Zhong

    2011-03-22

    High mechanical performances of macroscopic graphene oxide (GO) papers are attracting great interest owing to their merits of lightweight and multiple functionalities. However, the loading role of individual nanosheets and its effect on the mechanical properties of the macroscopic GO papers are not yet well understood. Herein, we effectively tailored the interlayer adhesions of the GO papers by introducing small molecules, that is, glutaraldehyde (GA) and water molecules, into the gallery regions. With the help of in situ Raman spectroscopy, we compared the varied load-reinforcing roles of nanosheets, and further predicted the Young's moduli of the GO papers. Systematic mechanical tests have proven that the enhancement of the tensile modulus and strength of the GA-treated GO paper arose from the improved load-bearing capability of the nanosheets. On the basis of Raman and macroscopic mechanical tests, the influences of interlayer adhesions on the fracture mechanisms of the strained GO papers were inferred.

  9. Deformation Behavior of Hot Isostatic Pressing FGH96 Superalloy

    Institute of Scientific and Technical Information of China (English)

    LIU Yuhong; LI Fuguo; YU Hongbo

    2006-01-01

    The deformation behavior of hot isostatic pressing (HIP) FGH96 superalloy was characterized in the temperature range of 1 000-1 100 ℃ and strain rate range of 0. 001-0.1 s-1 using hot compression testing. The flow curves of HIP FGH96 superalloy during hot deformation was analyzed systematically. The results show that deformation temperature, strain rate and strain are the main influence factors on flow stress of HIP FGH96 superalloy during hot deformation. The flow stress displays a peak at a critical strain and then decreases with further increase in strain. For a given strain, the flow stress decreases with the increase of deformation temperature, and increases with the increase of strain rate. A mathematical model of these flow curves was established through regression analysis and taking the strain as a modification factor. The calculated stress values agree well with the experimental values.

  10. The Cyclic Deformation Behavior of Severe Plastic Deformation (SPD Metals and the Influential Factors

    Directory of Open Access Journals (Sweden)

    Charles C. F. Kwan

    2012-02-01

    Full Text Available A deeper understanding of the mechanical behavior of ultra-fine (UF and nanocrystalline (NC grained metals is necessary with the growing interest in using UF and NC grained metals for structural applications. The cyclic deformation response and behavior of UF and NC grained metals is one aspect that has been gaining momentum as a major research topic for the past ten years. Severe Plastic Deformation (SPD materials are often in the spotlight for cyclic deformation studies as they are usually in the form of bulk work pieces and have UF and NC grains. Some well known techniques in the category of SPD processing are High Pressure Torsion (HPT, Equal Channel Angular Pressing (ECAP, and Accumulative Roll-Bonding (ARB. In this report, the literature on the cyclic deformation response and behavior of SPDed metals will be reviewed. The cyclic response of such materials is found to range from cyclic hardening to cyclic softening depending on various factors. Specifically, for SPDed UF grained metals, their behavior has often been associated with the observation of grain coarsening during cycling. Consequently, the many factors that affect the cyclic deformation response of SPDed metals can be summarized into three major aspects: (1 the microstructure stability; (2 the limitation of the cyclic lifespan; and lastly (3 the imposed plastic strain amplitude.

  11. Deformation behavior of curling strips on tearing tubes

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ji Won; Kwon, Tae Soo; Jung, Hyun Seung; Kim, Jin Sung [Dept. of Robotics and Virtual Engineering, Korea University of Science and Technology, Seoul (Korea, Republic of)

    2015-10-15

    This paper discusses the analysis of the curl deformation behavior when a dynamic force is applied to a tearing tube installed on a flat die to predict the energy absorption capacity and deformation behavior. The deformation of the tips of the curling strips was obtained when the curl tips and tube body are in contact with each other, and a formula describing the energy dissipation rate caused by the deformation of the curl tips is proposed. To improve this formula, we focused on the variation of the curl radius and the reduced thickness of the tube. A formula describing the mean curl radius is proposed and verified using the curl radius measurement data of collision test specimens. These improved formulas are added to the theoretical model previously proposed by Huang et al. and verified from the collision test results of a tearing tube.

  12. Three-Dimensional Crystal Plasticity Finite Element Simulation of Hot Compressive Deformation Behaviors of 7075 Al Alloy

    Science.gov (United States)

    Li, Lei-Ting; Lin, Y. C.; Li, Ling; Shen, Lu-Ming; Wen, Dong-Xu

    2015-03-01

    Three-dimensional crystal plasticity finite element (CPFE) method is used to investigate the hot compressive deformation behaviors of 7075 aluminum alloy. Based on the grain morphology and crystallographic texture of 7075 aluminum alloy, the microstructure-based representative volume element (RVE) model was established by the pole figure inversion approach. In order to study the macroscopic stress-strain response and microstructural evolution, the CPFE simulations are performed on the established microstructure-based RVE model. It is found that the simulated stress-strain curves and deformation texture well agree with the measured results of 7075 aluminum alloy. With the increasing deformation degree, the remained initial weak Goss texture component tends to be strong and stable, which may result in the steady flow stress. The grain orientation and grain misorientation have significant effects on the deformation heterogeneity during hot compressive deformation. In the rolling-normal plane, the continuity of strain and misorientation can maintain across the low-angle grain boundaries, while the discontinuity of strain and misorientation is observed at the high-angle grain boundaries. The simulated results demonstrate that the developed CPFE model can well describe the hot compressive deformation behaviors of 7075 aluminum alloy under elevated temperatures.

  13. MACROSCOPIC RIVERS

    NARCIS (Netherlands)

    VANDENBERG, IP

    1991-01-01

    We present a mathematical model for the ''river-phenomenon'': striking concentrations of trajectories of ordinary differential equations. This model of ''macroscopic rivers'' is formulated within nonstandard analysis, and stated in terms of macroscopes and singular perturbations. For a subclass, the

  14. Deformation Behavior of Severely Deformed Al and Related Mechanisms Through Warm Tensile Test

    Science.gov (United States)

    Charkhesht, V.; Kazeminezhad, M.

    2017-01-01

    Flow stress and ductility behaviors of the annealed and severely deformed Al were investigated at warm deformation temperatures. Constrained groove pressing (CGP) method as a severe plastic deformation process was used. The tensile test was carried out at the temperature range of the 298-573 K and strain rate range of 0.001-0.1 s-1 to present the elevated temperature deformation behavior utilizing hyperbolic sine constitutive equation. The flow stress of the CGPed sample is increased with the number of CGP passes and decreased with temperature. Dynamic recovery and strain softening are found as main restoration mechanisms. Flow stress amounts are not remarkably affected by the strain rate. Values of the elongation are decreased with the number of CGP passes. Values of the calculated strain rate sensitivity are utilized to justify the elongation behavior. Shear bands created by CGP remarkably decrease the fracture elongation values. Temperature interval of 298-473 K cannot remarkably affect the flow stress and ductility. The interval of 473-573 K is chosen as critical temperature interval in which the values of flow stress and elongation are remarkably decreased and increased, respectively. Increasing the temperature up to 573 K causes recrystallization in shear bands. Scanning electron microscope was used to study fracture surface which can truly predict the elongation behavior. With increasing the temperature, the shear decohesion area is gradually replaced with fully dimpled structures. Finally, hot deformation activation energy for CGPed samples was calculated about 85 kJ/mol which is close to the grain boundary diffusion activation energy in pure Al.

  15. Deformation and fatigue behavior of SSME turbopump blade materials

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1987-01-01

    Directionally solidified and single crystal superalloys which are intended for use as turbopump blade materials are anisotropic both elastically and plastically. Therefore, isotropic constitutive models must be modified. Several models which are now being developed are based on metallurgical theories of deformation in these types of alloys. However, these theories have not been fully justified, and the temperature and strain regimes over which they may be valid are poorly defined. The objective of this work is to study the deformation behavior of the alloys, in order to determine the validity of these models and to thereby support the ongoing research efforts in solid mechanics.

  16. Modeling and simulation of deformation and fracture behavior of components made of fully lamellar {gamma}TiAl alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kabir, Mohammad Rizviul [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

    2008-07-01

    The present work deals with the modeling and simulation of deformation and fracture behavior of fully lamellar {gamma}TiAl alloy; focusing on understanding the variability of local material properties and their influences on translamellar fracture. Afracture model has been presented that takes the inhomogeneity of the local deformation behavior of the lamellar colonies as well as the variability in fracture strength and toughness into consideration. To obtain the necessary model parameters, a hybrid methodology of experiments and simulations has been adopted. The experiments were performed at room temperature that demonstrates quasi-brittle response of the TiAl polycrystal. Aremarkable variation in stress-strain curves has been found in the tensile tests. Additional fracture tests showed significant variations in crack initiation and propagation during translamellar fracture. Analyzing the fracture surfaces, the micromechanical causes of these macroscopic scatter have been explained. The investigation shows that the global scatter in deformation and fracture response is highly influenced by the colony orientation and tilting angle with respect to the loading axis. The deformation and fracture behavior have been simulated by a finite element model including the material decohesion process described by a cohesive model. In order to capture the scatter of the macroscopic behavior, a stochastic approach is chosen. The local variability of stressstrain in the polycrystal and the variability of fracture parameters of the colonies are implemented in the stochastic approach of the cohesive model. It has been shown that the proposed approach is able to predict the stochastic nature of crack initiation and propagation as observed from the experiments. The global specimen failure with stable or unstable crack propagation can be explained in terms of the local variation of material properties. (orig.)

  17. Investigation on hot deformation behavior of AZ31 madnesium alloy

    Institute of Scientific and Technical Information of China (English)

    汪凌云; HUANG; Guangsheng; 等

    2002-01-01

    The hot compressive deformation of extruded AZ31 magnesium alloy with the mass fractions of Al and Zn equal to 3%and 1% respectively is studied by a Gleeble-1500D thermal mechanical simulator over the temperature range from 200℃to 400℃ and the strain rate from 10-3 s-1 to 100s-1.The true stress-strain curves of the strain of 65% are tested.The deformation activation energy is obtained and the flow stress model is established by analyzng the effects of strain rate and temperature on the flow stress.Zener-Hollomon parameter is introduced to describe the softening behaviors of AZ31 magnesium alloy resulted from dynamic recrystallization during the hot compressive deformation,whose natural logarithm is linear with the critical strain of dynamic recrystallization.

  18. Hot deformation behavior of delta-processed superalloy 718

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y., E-mail: wangyanhit@yahoo.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); School of Aeronautics and Astronautics, Central South University, Changsha 410083 (China); Shao, W.Z.; Zhen, L.; Zhang, B.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2011-03-25

    Research highlights: {yields} The peak stress for hot deformation can be described by the Z parameter. {yields} The grain size of DRX was inversely proportional to the Z parameter. {yields} The dissolution of {delta} phases was greatly accelerated under hot deformation. {yields}The {delta} phase stimulated nucleation can serve as the main DRX mechanism. - Abstract: Flow stress behavior and microstructures during hot compression of delta-processed superalloy 718 at temperatures from 950 to 1100 deg. C with strain rates of 10{sup -3} to 1 s{sup -1} were investigated by optical microscopy (OM), electron backscatter diffraction (EBSD) technique and transmission electron microscopy (TEM). The relationship between the peak stress and the deformation conditions can be expressed by a hyperbolic-sine type equation. The activation energy for the delta-processed superalloy 718 is determined to be 467 kJ/mol. The change of the dominant deformation mechanisms leads to the decrease of stress exponent and the increase of activation energy with increasing temperature. The dynamically recrystallized grain size is inversely proportional to the Zener-Hollomon (Z) parameter. It is found that the dissolution rate of {delta} phases under hot deformation conditions is much faster than that under static conditions. Dislocation, vacancy and curvature play important roles in the dissolution of {delta} phases. The main nucleation mechanisms of dynamic recrystallization (DRX) for the delta-processed superalloy 718 include the bulging of original grain boundaries and the {delta} phase stimulated DRX nucleation, which is closely related to the dissolution behavior of {delta} phases under certain deformation conditions.

  19. Numerical Investigation of the Macroscopic Mechanical Behavior of NiTi-Hybrid Composites Subjected to Static Load-Unload-Reload Path

    Science.gov (United States)

    Taheri-Behrooz, Fathollah; Kiani, Ali

    2017-04-01

    Shape memory alloys (SMAs) are a type of shape memory materials that recover large deformation and return to their primary shape by rising temperature. In the current research, the effect of embedding SMA wires on the macroscopic mechanical behavior of glass-epoxy composites is investigated through finite element simulations. A perfect interface between SMA wires and the host composite is assumed. Effects of various parameters such as SMA wires volume fraction, SMA wires pre-strain and temperature are investigated during loading-unloading and reloading steps by employing ANSYS software. In order to quantify the extent of induced compressive stress in the host composite and residual tensile stress in the SMA wires, a theoretical approach is presented. Finally, it was shown that smart structures fabricated using composite layers and pre-strained SMA wires exhibited overall stiffness reduction at both ambient and elevated temperatures which were increased by adding SMA volume fraction. Also, the induced compressive stress on the host composite was increased remarkably using 4% pre-strained SMA wires at elevated temperature. Results obtained by FE simulations were in good correlation with the rule of mixture predictions and available experimental data in the literature.

  20. Numerical Investigation of the Macroscopic Mechanical Behavior of NiTi-Hybrid Composites Subjected to Static Load-Unload-Reload Path

    Science.gov (United States)

    Taheri-Behrooz, Fathollah; Kiani, Ali

    2017-02-01

    Shape memory alloys (SMAs) are a type of shape memory materials that recover large deformation and return to their primary shape by rising temperature. In the current research, the effect of embedding SMA wires on the macroscopic mechanical behavior of glass-epoxy composites is investigated through finite element simulations. A perfect interface between SMA wires and the host composite is assumed. Effects of various parameters such as SMA wires volume fraction, SMA wires pre-strain and temperature are investigated during loading-unloading and reloading steps by employing ANSYS software. In order to quantify the extent of induced compressive stress in the host composite and residual tensile stress in the SMA wires, a theoretical approach is presented. Finally, it was shown that smart structures fabricated using composite layers and pre-strained SMA wires exhibited overall stiffness reduction at both ambient and elevated temperatures which were increased by adding SMA volume fraction. Also, the induced compressive stress on the host composite was increased remarkably using 4% pre-strained SMA wires at elevated temperature. Results obtained by FE simulations were in good correlation with the rule of mixture predictions and available experimental data in the literature.

  1. Hot deformation behavior of EA4T steel

    Institute of Scientific and Technical Information of China (English)

    Gang XU; Lina WANG; Shiqi LI; Le WANG

    2012-01-01

    The compressive deformation behavior of EA4T steel was investigated at temperatures ranging from 950 to 1150℃ and strain rates from 0.1 to 20 s-1 on Gleeble-1500 thermo-simulation machine.The work hardening rate versus stress curves were used to determine the characteristic points of flow curves.The application of constitutive equations to determine the hot working constants of this material was discussed.Furthermore,the effect of Zener-Hollomon parameter (Z) on the characteristic points of flow curves was studied using the power law relation.The deformation activation energy of this steel was determined as 309.5 kJ/mol.Some behaviors were compared to other steels.

  2. Role of Steel Object Surface Condition on Behavior During Deformation

    Science.gov (United States)

    D'yachenko, S. S.; Ponomarenko, I. V.; Dub, S. N.

    2015-09-01

    Comparative analysis is provided for specimen mechanical properties of steels 18KhGT and 20Kh with tensile testing in relation to surface treatment: grinding, polishing, nitriding, carburizing, and ion-plasma treatment. It is shown that surface condition has a considerable effect on specimen behavior during deformation. It is established that the most favorable effect applies to ion bombardment with low-energy ions recommended as an effective method for improving component structural strength.

  3. Equation-Free Analysis of Macroscopic Behavior in Traffic and Pedestrian Flow

    DEFF Research Database (Denmark)

    Marschler, Christian; Sieber, Jan; Hjorth, Poul G.;

    2014-01-01

    . This will facilitate a study of how the model behavior depends on parameter values including an understanding of transitions between different types of qualitative behavior. These methods are introduced and explained for traffic jam formation and emergence of oscillatory pedestrian counter flow in a corridor...

  4. Statistical model for the mechanical behavior of the tissue engineering non-woven fibrous matrices under large deformation.

    Science.gov (United States)

    Rizvi, Mohd Suhail; Pal, Anupam

    2014-09-01

    The fibrous matrices are widely used as scaffolds for the regeneration of load-bearing tissues due to their structural and mechanical similarities with the fibrous components of the extracellular matrix. These scaffolds not only provide the appropriate microenvironment for the residing cells but also act as medium for the transmission of the mechanical stimuli, essential for the tissue regeneration, from macroscopic scale of the scaffolds to the microscopic scale of cells. The requirement of the mechanical loading for the tissue regeneration requires the fibrous scaffolds to be able to sustain the complex three-dimensional mechanical loading conditions. In order to gain insight into the mechanical behavior of the fibrous matrices under large amount of elongation as well as shear, a statistical model has been formulated to study the macroscopic mechanical behavior of the electrospun fibrous matrix and the transmission of the mechanical stimuli from scaffolds to the cells via the constituting fibers. The study establishes the load-deformation relationships for the fibrous matrices for different structural parameters. It also quantifies the changes in the fiber arrangement and tension generated in the fibers with the deformation of the matrix. The model reveals that the tension generated in the fibers on matrix deformation is not homogeneous and hence the cells located in different regions of the fibrous scaffold might experience different mechanical stimuli. The mechanical response of fibrous matrices was also found to be dependent on the aspect ratio of the matrix. Therefore, the model establishes a structure-mechanics interdependence of the fibrous matrices under large deformation, which can be utilized in identifying the appropriate structure and external mechanical loading conditions for the regeneration of load-bearing tissues.

  5. Size-dependent deformation behavior of nanocrystalline graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhi [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Huang, Yuhong [College of Physics and Information Technology, Shaanxi Normal University, Xi’an 710062, Shaanxi (China); Ma, Fei, E-mail: mafei@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Sun, Yunjin [Faculty of Food Science and Engineering, Beijing University of Agriculture, Beijing Key Laboratory of Agricultural Product Detection and Control of Spoilage Organisms and Pesticide Residue, Beijing Laboratory of Food Quality and Safety, Beijing 102206 (China); Xu, Kewei, E-mail: kwxu@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049, Shaanxi (China); Department of Physics and Opt-electronic Engineering, Xi’an University of Arts and Science, Xi’an 710065, Shaanxi (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-08-15

    Highlights: • MD simulation is conducted to study the deformation of nanocrystalline graphene. • Unexpectedly, the elastic modulus decreases with the grain size considerably. • But the fracture stress and strain are nearly insensitive to the grain size. • A composite model with grain domains and GBs as two components is suggested. - Abstract: Molecular dynamics (MD) simulation is conducted to study the deformation behavior of nanocrystalline graphene sheets. It is found that the graphene sheets have almost constant fracture stress and strain, but decreased elastic modulus with grain size. The results are different from the size-dependent strength observed in nanocrystalline metals. Structurally, the grain boundaries (GBs) become a principal component in two-dimensional materials with nano-grains and the bond length in GBs tends to be homogeneously distributed. This is almost the same for all the samples. Hence, the fracture stress and strain are almost size independent. As a low-elastic-modulus component, the GBs increase with reducing grain size and the elastic modulus decreases accordingly. A composite model is proposed to elucidate the deformation behavior.

  6. Analysis on the deformation and fracture behavior of carbon steel by in situ tensile test

    Institute of Scientific and Technical Information of China (English)

    Fan Li; Haibo Huang

    2006-01-01

    The deformation and fracture behaviors of low-carbon steel, medium-carbon steel, and high-carbon steel were studied on internal microstructure using the scanning electron microscopy in situ tensile test. The microstructure mechanism of their deformation and fracture behavior was analyzed. The results show that the deformation and fracture behavior of low-carbon steel depends on the grain size of ferrite, the deformation and fracture behavior of medium-carbon steel depends on the size of ferrite grain and pearlite lump,and the deformation and fracture behavior of high-carbon steel depends on the size of pearlite lump and the pearlitic interlamellar spacing.

  7. Deformation behavior of dispersion-strengthened copper at high temperature

    Institute of Scientific and Technical Information of China (English)

    WANG Mengjun; ZHANG Yingchun; LUO Yun; LIU Xinyu

    2006-01-01

    The deformation behavior of dispersion-strengthened copper with different compositions was investigated by hot compression simulation tests on a Gleeble-1500 thermal-mechanical simulator. The microstructure during deformation at high temperature was also studied. The result shows that at the beginning of hot compression simulation, the flowing stress of the dispersion-strengthened copper quickly attains a peak value and the stress shows a greater decrease when the temperature is higher and the strain rate is lower. The dispersion particles lead to an obvious increase in the recrystallization temperature. Under experimental conditions, dynamic recovery is the main softening method. The constitutive equation at high temperature of 1.2%Al2O3-0.4%WC/Cu is obtained.

  8. Deformation Behavior across the Zircon-Scheelite Phase Transition

    Science.gov (United States)

    Yue, Binbin; Hong, Fang; Merkel, Sébastien; Tan, Dayong; Yan, Jinyuan; Chen, Bin; Mao, Ho-Kwang

    2016-09-01

    The pressure effects on plastic deformation and phase transformation mechanisms of materials are of great importance to both Earth science and technological applications. Zircon-type materials are abundant in both nature and the industrial field; however, there is still no in situ study of their deformation behavior. Here, by employing radial x-ray diffraction in a diamond anvil cell, we investigate the dislocation-induced texture evolution of zircon-type gadolinium vanadate (GdVO4 ) in situ under pressure and across its phase transitions to its high-pressure polymorphs. Zircon-type GdVO4 develops a (001) compression texture associated with dominant slip along ⟨100 ⟩{001 } starting from 5 GPa. This (001) texture transforms into a (110) texture during the zircon-scheelite phase transition. Our observation demonstrates a martensitic mechanism for the zircon-scheelite transformation. This work will help us understand the local deformation history in the upper mantle and transition zone and provides fundamental guidance on material design and processing for zircon-type materials.

  9. Deformation Behavior across the Zircon-Scheelite Phase Transition.

    Science.gov (United States)

    Yue, Binbin; Hong, Fang; Merkel, Sébastien; Tan, Dayong; Yan, Jinyuan; Chen, Bin; Mao, Ho-Kwang

    2016-09-23

    The pressure effects on plastic deformation and phase transformation mechanisms of materials are of great importance to both Earth science and technological applications. Zircon-type materials are abundant in both nature and the industrial field; however, there is still no in situ study of their deformation behavior. Here, by employing radial x-ray diffraction in a diamond anvil cell, we investigate the dislocation-induced texture evolution of zircon-type gadolinium vanadate (GdVO_{4}) in situ under pressure and across its phase transitions to its high-pressure polymorphs. Zircon-type GdVO_{4} develops a (001) compression texture associated with dominant slip along ⟨100⟩{001} starting from 5 GPa. This (001) texture transforms into a (110) texture during the zircon-scheelite phase transition. Our observation demonstrates a martensitic mechanism for the zircon-scheelite transformation. This work will help us understand the local deformation history in the upper mantle and transition zone and provides fundamental guidance on material design and processing for zircon-type materials.

  10. A perspectival version of the modal interpretation of quantum mechanics and the origin of macroscopic behavior

    CERN Document Server

    Béné, G J; Bene, Gyula; Dieks, Dennis

    2001-01-01

    We study the process of observation (measurement), within the framework of a `perspectival' (`relational', `relative state') version of the modal interpretation of quantum mechanics. We show that if we assume certain features of discreteness and determinism in the operation of the measuring device (which could be a part of the observer's nerve system), this gives rise to classical characteristics of the observed properties, in the first place to spatial localization. We investigate to what extent semi-classical behavior of the object system itself (as opposed to the observational system) is needed for the emergence of classicality. Decoherence is an essential element in the mechanism of observation that we assume, but it turns out that in our approach no environment-induced decoherence on the level of the object system is required for the emergence of classical properties.

  11. Static Recrystallization Behavior of Hot Deformed Austenite for Micro-Alloyed Steel

    Institute of Scientific and Technical Information of China (English)

    Jie HUANG; Zhou XU; Xin XING

    2003-01-01

    Static recrystallization behavior of austenite for micro-alloyed steel during hot rolling was studied and the influence (τ-ε diagram) of holding time and deformation at different deformations and isothermal temperatures on microstructuralstate of austen

  12. Impact of the irregular microgeometry of polyurethane foam on the macroscopic acoustic behavior predicted by a unit-cell model.

    Science.gov (United States)

    Doutres, O; Ouisse, M; Atalla, N; Ichchou, M

    2014-10-01

    This paper deals with the prediction of the macroscopic sound absorption behavior of highly porous polyurethane foams using two unit-cell microstructure-based models recently developed by Doutres, Atalla, and Dong [J. Appl. Phys. 110, 064901 (2011); J. Appl. Phys. 113, 054901 (2013)]. In these models, the porous material is idealized as a packing of a tetrakaidecahedra unit-cell representative of the disordered network that constitutes the porous frame. The non-acoustic parameters involved in the classical Johnson-Champoux-Allard model (i.e., porosity, airflow resistivity, tortuosity, etc.) are derived from characteristic properties of the unit-cell and semi-empirical relationships. A global sensitivity analysis is performed on these two models in order to investigate how the variability associated with the measured unit-cell characteristics affects the models outputs. This allows identification of the possible limitations of a unit-cell micro-macro approach due to microstructure irregularity. The sensitivity analysis mainly shows that for moderately and highly reticulated polyurethane foams, the strut length parameter is the key parameter since it greatly impacts three important non-acoustic parameters and causes large uncertainty on the sound absorption coefficient even if its measurement variability is moderate. For foams with a slight inhomogeneity and anisotropy, a micro-macro model associated to cell size measurements should be preferred.

  13. Fatigue Behavior and Deformation Mechanisms in Inconel 718 Superalloy Investigated

    Science.gov (United States)

    2005-01-01

    The nickel-base superalloy Inconel 718 (IN 718) is used as a structural material for a variety of components in the space shuttle main engine (SSME) and accounts for more than half of the total weight of this engine. IN 718 is the bill-of-material for the pressure vessels of nickel-hydrogen batteries for the space station. In the case of the space shuttle main engine, structural components are typically subjected to startup and shutdown load transients and occasional overloads in addition to high-frequency vibratory loads from routine operation. The nickel-hydrogen battery cells are prooftested before service and are subjected to fluctuating pressure loads during operation. In both of these applications, the structural material is subjected to a monotonic load initially, which is subsequently followed by fatigue. To assess the life of these structural components, it is necessary to determine the influence of a prior monotonic load on the subsequent fatigue life of the superalloy. An insight into the underlying deformation and damage mechanisms is also required to properly account for the interaction between the prior monotonic load and the subsequent fatigue loading. An experimental investigation was conducted to establish the effect of prior monotonic straining on the subsequent fatigue behavior of wrought, double-aged, IN 718 at room temperature. First, monotonic strain tests and fully-reversed, strain-controlled fatigue tests were conducted on uniform-gage-section IN 718 specimens. Next, fully reversed fatigue tests were conducted under strain control on specimens that were monotonically strained in tension. Results from this investigation indicated that prior monotonic straining reduced the fatigue resistance of the superalloy particularly at the lowest strain range. Some of the tested specimens were sectioned and examined by transmission electron microscopy to reveal typical microstructures as well as the active deformation and damage mechanisms under each of

  14. Deformation behavior of reduced activation ferritic steel during tensile test

    Energy Technology Data Exchange (ETDEWEB)

    Shiba, Kiyoyuki [Department of Material Science and Engineering, Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibakaki 319-1195 (Japan)]. E-mail: shiba@realab01.tokai.jaeri.go.jp; Hirose, Takanori [Department of Fusion Engineering Research, Japan Atomic Energy Research Institute, 801-1 Mukouyama, Naka, Ibaraki 311-0193 (Japan)

    2006-02-15

    Deformation behavior of reduced activation martensitic steel F82H during tensile tests were studied. True stress-true strain diagrams were calculated with minimum diameter determined from the specimen profile obtained by laser micro-gauge scanning the diameter along the longitudinal direction during tensile test. Cylindrical specimens of F82H were used for the measurement and test temperatures were room temperature (RT), 300, 400, 500 and 600 deg. C. Tensile tests were carried out with 1 x 10{sup -4} s{sup -1} of strain rate. Other strain rates (1 x 10{sup -3} and 1 x 10{sup -5} s{sup -1}) were applied for the tests at RT. Although uniform elongation of F82H is relatively small at elevated temperature, true stress increases to fracture after necking starts. True stress decreases temporarily after yielding at 600 deg. C, but it increases again to fracture like the specimens tested at lower temperatures. Influence of strain rate to true stress-true strain relationship at room temperature was small, but unstable deformation occurred in narrower area at higher strain rate.

  15. Viscoelastoplastic constitutive model for creep deformation behavior of asphalt sand

    Institute of Scientific and Technical Information of China (English)

    叶永; 杨新华; 陈传尧

    2008-01-01

    A uniaxial viscoelastoplastic model that can describe whole creep behaviors of asphalt sand at different temperatures was presented.The model was composed of three submodels in series,which describe elastoplastic,viscoelastic and viscoplastic characteristics respectively.The constitutive equation was established for uniaxial loading condition,and the creep representation was also obtained.The constitutive parameters were determined by uniaxial compression tests under controlled-stress of 0.1 MPa with five different test temperatures of 20,40,45,50 and 60 ℃.Expressions of the model parameters in terms of temperatures were also given.The model gave prediction at various temperatures consistent with the experimental results,and can reflect the total deformation characterization of asphalt sands.

  16. Type-IV Pilus Deformation Can Explain Retraction Behavior

    CERN Document Server

    Ghosh, Ranajay; Vaziri, Ashkan

    2014-01-01

    Polymeric filament like type IV Pilus (TFP) can transfer forces in excess of 100pN during their retraction before stalling, powering surface translocation(twitching). Single TFP level experiments have shown remarkable nonlinearity in the retraction behavior influenced by the external load as well as levels of PilT molecular motor protein. This includes reversal of motion near stall forces when the concentration of the PilT protein is lowered significantly. In order to explain this behavior, we analyze the coupling of TFP elasticity and interfacial behavior with PilT kinetics. We model retraction as reaction controlled and elongation as transport controlled process. The reaction rates vary with TFP deformation which is modeled as a compound elastic body consisting of multiple helical strands under axial load. Elongation is controlled by monomer transport which suffer entrapment due to excess PilT in the cell periplasm. Our analysis shows excellent agreement with a host of experimental observations and we prese...

  17. Deformation Behavior of Ultra-low Carbon Steel in Ferrite Region during Warm Processing

    Institute of Scientific and Technical Information of China (English)

    XU Guang; CHEN Zhenye; LIU Li; YU Shengfu

    2008-01-01

    The hot deformation experiments of ultra-low carbon steel in ferrite range were carried out ina hot simulator in order to research hot deformation behaviors of ultra-low carbon steel in ferrite range at low temperature.The results show that the influences of deformation parameters on flow stress are different to those in austenitic deformation.The deformation characteristic parameters were calculated for ultra-low carbon steel in ferrite region.The flow stress equation for ultra-low carbon steel in ferritic deformation at low temperature was obtained.

  18. Effect of strain rates on deformation behaviors of an in situ Ti-based metallic glass matrix composite

    Science.gov (United States)

    Jiao, Z. M.; Wang, Z. H.; Chu, M. Y.; Wang, Y. S.; Yang, H. J.; Qiao, J. W.

    2016-06-01

    Quasi-static and dynamic deformation behaviors of an in situ dendrite-reinforced metallic glass matrix composite: Ti56Zr18V10Cu4Be12 were investigated. Upon quasi-static compression, the composite exhibits distinguished work hardening, accompanied by the ultimate strength of 1290 MPa and the plasticity of 20 %. The improved plasticity is attributed to the multiplication of shear bands within the glass matrix and pileups of dislocations within the dendrites. Upon dynamic compression, the stable plastic flow prevails and the yielding stress increases with the strain rate. The macroscopic plasticity decreases considerably, since the shear bands cannot be effectively hindered by dendrites with deteriorated toughness. The dendrite-dominated mechanism results in the positive strain-rate sensitivity, and the Cowper-Symonds model is employed to depict the strain-rate dependency of yielding strength.

  19. Combination of Different In Situ Characterization Techniques and Scanning Electron Microscopy Investigations for a Comprehensive Description of the Tensile Deformation Behavior of a CrMnNi TRIP/TWIP Steel

    Science.gov (United States)

    Weidner, Anja; Biermann, Horst

    2015-08-01

    The class of low-carbon, high-alloy CrMnNi steels exhibits outstanding mechanical properties with respect to high strength and ductility due to either transformation-induced plasticity (TRIP) or twinning-induced plasticity (TWIP) effect depending on chemical composition and deformation temperature. However, the ongoing deformation mechanisms like the formation of stacking faults, martensitic phase transformation or deformation-induced twinning are overlapping and the kinetics of the microstructure evolution are quite complex. Therefore, in addition to macroscopic deformation tests and microstructural investigations by scanning electron microscopy, a combination of several in situ characterization techniques with either high lateral and/or temporal resolution as well as providing integral volume information were chosen in order to give a thoroughly and comprehensive description of the deformation behavior of CrMnNi TRIP/TWIP steels. In addition, the complementary in situ techniques like in situ nanoindentation, micro-digital image correlation, and acoustic emission measurements provide excellent possibility for description of materials behavior on a multiscale level from the submicrometer scale up to the macroscopic range. The results obtained by the complementary techniques can support the future modeling of the deformation behavior of TRIP/TWIP steels dependent on chemical composition, temperature, grain size and grain orientation.

  20. Relation of deformation behavior with precipitation and groundwater of the Babaoshan fault in Beijing

    Institute of Scientific and Technical Information of China (English)

    HUANG Fu-qiong; CHEN Yong; BAI Chang-qing; ZHANG Jing; YAN Rui; YANG Ming-bo; LAN Cong-xin; ZHANG Xiao-dong; JIANG Zai-sen

    2005-01-01

    We discuss the influence of precipitation and groundwater on the deformation behavior of the Babaoshan fault of Beijing by using long-term observation data from Dahuichang station during 1970~2003. The results show that a)the pore pressure on fault zone as well as the fault deformation behavior exhibited periodically variation as precipitation changed steadily and periodically; b) the periodicity of the pore pressure of fault zones disappeared and the manner of fault deformation behavior changed when precipitation was small and/or was in aberrance. This implies that rainfall plays a key role in fault deformation behavior through changing the pore pressure of fault zones. Combining the existing results about the Babaoshan fault, it is concluded that precipitation and groundwater may adjust the stress/strain field by controlling the deformation behavior of the fault, which can provide direct observation evidence for the interaction of fluid and solid in shallow crust of the Earth.

  1. Thermal deformation behavior and microstructure of nuclear austenitic stainless steel

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Gleeble-1500D thermal simulation tester was employed in the hot-compression investigation of as-cast nuclear 304 austenitic stainless steel under conditions: deformation temperature 950―1200℃; deformations 30% and 50%; deformation rates 0.01 and 0.1 s?1. The results show that the flow stress decreases with temperature rise under the same strain rate and deformation, that the flow stress increases with deformation under the same temperature and strain rate, and that the flow stress increases with strain rate under the same temperature condition, i.e., work hardening becomes distinct. Materials exhibit better strength-toughness when the strain rate is 0.01 s-1, the deformation is 50%, and the temperature is 1050℃.

  2. Deformation behavior and mechanisms of Ti- 1023 alloy

    Institute of Scientific and Technical Information of China (English)

    BAO Ru-qiang; HUANG Xu; CAO Chun-xiao

    2006-01-01

    The deformation behavior and mechanisms of Ti-1023 alloy were studied in the temperature range of 650-900 ℃ and strain rate range of 0.001-10 s-1 by compression and tensile tests. The results show that in a limited strain rate range of 0.001-0.1 s-1,the kinetic rate equation is obeyed and a linear fit is obtained at all the temperatures. The apparent activation energy is 322 kJ/mol in the α-β region and 160 kJ/mol in the β region, respectively. Power dissipation maps of this alloy developed by using Gleeble test data show three domains in the tested range. Superplasticity, marked by abnormal elongation at 700 ℃, occurs in the temperature range of 650-750 ℃ and at strain rates below about 0.03 s-1 Large grain superplasticity takes place in the temperature range of 750-850℃ and strain rates range of 0.001-0.03 s-1. Dynamic recrystallization occurs in the temperature range of 850-900 ℃ and at strain rates below about 1 s-1. The instability maps of this alloy were also developed.

  3. Effects of hydrogenation on ambient deformation behaviors of Ti-45Al alloy

    Institute of Scientific and Technical Information of China (English)

    SU Yan-qing; LIU Xin-wang; ZHAO Long; WANG Liang; GUO Jing-jie; FU Heng-zhi

    2009-01-01

    Effects of hydrogenation on ambient deformation behaviors of Ti-45Al alloy were studied. The stress-strain curves demonstrate that the plastic deformation of the hydrogenated alloys becomes more remarkable than that of the unhydrogenated alloy.Meanwhile, the compression strength and maximum strain are reduced. Both the hydride and hydrogen atoms in the interstices affect the compression deformation behaviors. The reason of the hydrogen-induced embrittlement is that the hydride is easy to become the nucleus of the cracks. And the variation of plastic deformation process is attributed to hydrogen-promoted emission, multiplication and motion of dislocation.

  4. Experimental Investigation on Creep Deformation Behavior of Medium-strength Marble Rock

    OpenAIRE

    Li Yong; Zhu Weishen; Li Shucai

    2014-01-01

    The creep deformation behavior of rocks has significant effect on the stability of underground structures. This study presents the short-term and creep deformation behavior of medium-strength marble rock using a conventional uniaxial compression testing machine and a servo-controlled rheology testing machine. The uniaxial compressive strength is obtained by the uniaxial compression testing machine. During the creep behavior test, two types of rock specimens (dry and water-saturated) are speci...

  5. Constitution modeling and deformation behavior of yttrium bearing TiAl alloy

    Institute of Scientific and Technical Information of China (English)

    CHEN Yuyong; YANG Fei; KONG Fantao; XIAO Shulong

    2011-01-01

    The deformation flow behaviors of Ti-45Al-5.4V-3.6Nb-0.3Y alloy at different temperatures and strain rates were studied by isothermal compressing simulation test. The apparent activation energy of deformation was calculated to be 402.096 kJ/mol and constitutive equation was established to describe the flow behavior. Microstructure and flow softening observations exhibited that Ti-45Al-5.4V-3.6Nb-0.3Y alloy had bad hot workability at low temperature (lower than 1 100 ℃) and high strain rate (higher than 0.5 s-1) characterized by localization deformation and instability. With deformation temperature higher than 1 150 ℃ and strain rate lower than 0.01 s-1, the alloy owned good hot deformability, and plenty of dynamic recrystallized grains could be observed in the deformed microstructures.

  6. Deformation behavior during nanoindentation in Ce-based bulk metallic glasses

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lingchen; XING Dongmei; ZHANG Taihua; WEI Bingchen; LI Weihuo; WANG Yuren

    2006-01-01

    The deformation behavior and the effect of the loading rate on the plastic deformation in Ce-based bulk metallic glasses (BMGs) were investigated through nanoindentation tests. The results showed that the loading rate dependence of plastic deformation during nanoindentation measurements in the Ce-based BMGs is quite unique in contrast to that of other BMG alloys. The load-displacement (P-h)curves of Ce60Al15Cu10Ni15 BMG exhibit a homogeneous plastic deformation at low loading rates, and a prominent serrated flow at high strain rates, whereas,the P-h curves of Ce65Al10Cu10Ni10Nb5 exhibit homogenous plastic deformation at all studied loading rates. The room temperature creep behavior could clearly be observed in these two alloys. The mechanism of the unique plastic deformation feature in the Ce-based BMGs was studied.

  7. Hot compression deformation behavior of the Mg-AI-Y-Zn magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    FANG Xiya; YI Danqing; WANG Bin; WU Chunping; ZHANG Hong

    2008-01-01

    The hot deformation behavior of a Mg-Al-Y-Zn magnesium alloy was investigated by hot compressive testing on a Gleeble-1500 thermal simulator at the temperanging from 523 to 673 K with the swain rate varying from 0.001 to 1s-1.The relationships among flow stress,swain rate,and deformation temperature were analyzed,and the deformation activation energy and stress exponent were calculated.Microstructure evolution of the alloy under different conditions was examined.The results indicated that the maximum value of the flow stress increased with the decrease of deformation temperature or the increase of swain rate.Under the present deformation conditions,dynamic recrystallization (DRX) oeettrred in the alloy,which was the main softening mechanism during deformation at elevated temperature.The deformation temperature and strain had significant effects on the microstructure of the alloy.

  8. Deformation behavior of laser bending of circular sheet metal

    Institute of Scientific and Technical Information of China (English)

    Q. Nadeem; S. J. Na

    2011-01-01

    @@ The application of a thermal source in non-contact forming of sheet metal has long been used.However, the replacement of this thermal source with a laser beam promises much greater controllability of the process.This yields a process with strong potential for application in aerospace, shipbuilding, automobile, and manufacturing industries, as well as the rapid manufacturing of prototypes and adjustment of misaligned components.%The application of a thermal source in non-contact forming of sheet metal has long been used. However, the replacement of this thermal source with a laser beam promises much greater controllability of the process. This yields a process with strong potential for application in aerospace, shipbuilding, automobile, and manufacturing industries, as well as the rapid manufacturing of prototypes and adjustment of misaligned components. Forming is made possible through laser-induced non-uniform thermal stresses. In this letter, we use the geometrical transition from rectangular to circle-shaped specimen and ring-shaped specimen to observe the effect of geometry on deformation in laser forming. We conduct a series of experiments on a wide range of specimen geometries. The reasons for this behavior are also analyzed. Experimental results are compared with simulated values using the software ABAQUS. The utilization of line energy is found to be higher in the case of laser forming along linear irradiation than along curved ones. We also analyze the effect of strain hindrance. The findings of the study may be useful for the inverse problem, which involves acquiring the process parameters for a known target shape of a wide range of complex shape geometries.

  9. Influence of thermally activated processes on the deformation behavior during low temperature ECAP

    Science.gov (United States)

    Fritsch, S.; Scholze, M.; F-X Wagner, M.

    2016-03-01

    High strength aluminum alloys are generally hard to deform. Therefore, the application of conventional severe plastic deformation methods to generate ultrafine-grained microstructures and to further increase strength is considerably limited. In this study, we consider low temperature deformation in a custom-built, cooled equal channel angular pressing (ECAP) tool (internal angle 90°) as an alternative approach to severely plastically deform a 7075 aluminum alloy. To document the maximum improvement of mechanical properties, these alloys are initially deformed from a solid solution heat-treated condition. We characterize the mechanical behavior and the microstructure of the coarse grained initial material at different low temperatures, and we analyze how a tendency for the PLC effect and the strain-hardening rate affect the formability during subsequent severe plastic deformation at low temperatures. We then discuss how the deformation temperature and velocity influence the occurrence of PLC effects and the homogeneity of the deformed ECAP billets. Besides the mechanical properties and these microstructural changes, we discuss technologically relevant processing parameters (such as pressing forces) and practical limitations, as well as changes in fracture behavior of the low temperature deformed materials as a function of deformation temperature.

  10. Characterizing volumetric deformation behavior of naturally occuring bituminous sand materials

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2009-05-01

    Full Text Available newly proposed hydrostatic compression test procedure. The test procedure applies field loading conditions of off-road construction and mining equipment to closely simulate the volumetric deformation and stiffness behaviour of oil sand materials. Based...

  11. Permanent deformation behavior of naturally occurring bituminous sands

    CSIR Research Space (South Africa)

    Anochie-Boateng, Joseph

    2008-01-01

    Full Text Available were compacted close to field densities and then tested for permanent deformation at two temperatures using a newly proposed test procedure. The procedure applied stress states and ratios determined from field-loading characteristics of haul trucks...

  12. Long-Time Behavior of Macroscopic Quantum Systems: Commentary Accompanying the English Translation of John von Neumann's 1929 Article on the Quantum Ergodic Theorem

    OpenAIRE

    Goldstein, Sheldon; Lebowitz, Joel L.; Tumulka, Roderich; Zanghi, Nino

    2010-01-01

    The renewed interest in the foundations of quantum statistical mechanics in recent years has led us to study John von Neumann's 1929 article on the quantum ergodic theorem. We have found this almost forgotten article, which until now has been available only in German, to be a treasure chest, and to be much misunderstood. In it, von Neumann studied the long-time behavior of macroscopic quantum systems. While one of the two theorems announced in his title, the one he calls the "quantum H-theore...

  13. STUDY ON THE HOT DEFORMATION BEHAVIORS OF Al-Zn-Mg-Cu-Cr ALUMINUM ALLOY

    Institute of Scientific and Technical Information of China (English)

    G.Y. Lin; Z.F. Zhang; H. Zhang; D.S. Peng; J. Zhou

    2008-01-01

    The hot deformation behaviors and mierostructures of Al-Zn-Mg-Cu-Cr aluminum alloy have been studied using thermal simulation test, optical microscopy and transmission electron microscopy. As a result, the true stress versus true strain curves and the microstructures under various deformation conditions are obtained. The microstructures gradually incline to dynamic-recrystallization with the deformation temperature rising and the recrystallization grains refine with the decrease of deformation temperature or with raising the strain rates. The quantitative relationship between the Zener-HoUomon parameter (Z) and average recrystallization grain size in the subsequent heat treatment is set up.

  14. Hot deformation behavior of rare earth magnesium alloy without pre-homogenization treatment

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The behavior and structure evolvement of as-cast Mg-Gd-Y-Nd-Zr magnesium alloy during the hot deformation process were discussed. The flow stress behavior of magnesium alloy over the strain rate range of 0.002-1 s-1 and the temperature range of 573-723 K was researched on Gleeble-1500D hot simulator under the maximum deformation degree of 60%. The experimental results show that the relationship between stress and strain is obviously affected by the strain rate and deformation temperature. The important softening mechanisms are eutectic melting and discontinuous dynamic recrystallization (DDRX) during deformation. The fragments of eutectie melting along the boundaries can turn round so as to take effect of the slippage between grains. The flow stress of Mg-7Gd-5Y-1.2Nd-Zr magnesium alloy during high temperature deformation can be represented by a Zener-Hollomon parameter in the hyperbolic Arrhenius-type equation. The strain coefficient n and deformation activation energy Q are evaluated by linear regression analysis. A, α and n in the analytical expressions of σ are fitted to be 2.401 93× 1015, 0.017 3 MPa-1 and 3.218 19,respectively. The hot deformation activation energy of alloy during hot deformation is 234.950 58 kJ/mol. The results also show that the structure of primitive microstructure has an effect on the plastic deformation.

  15. Influence of Mn Content and Hot Deformation on Transformation Behavior of C-Mn Steels

    Institute of Scientific and Technical Information of China (English)

    LI Long; DING Hua; DU Lin-xiu; WEN Jing-lin; SONG Hong-mei; ZHANG Pi-jun

    2008-01-01

    The hot deformation behaviors and the microstructural evolution of plain C-Mn steels with similar contents of C and Si but different contents of Mn have been investigated by compressive processing using Gleeble-1500 mechanical simulator. Influence of Mn and hot deformation on continuous cooling transformation of steels has been studied. The experimental results showed that deformation in austenite region accelerated transformation process, and the extent is dependent on the hot deformation and cooling conditions. The hot deformation would promote transformation process, but the increase of transformation temperature is dependent on Mn contents. The results have also shown that the effect of deformation on ferrite transformation becomes more obvious with the increase of Mn content at relatively low cooling rate.

  16. Work-hardening behavior of mild steel under cyclic deformation at finite strains

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Z. (Univ. Paris-Nord, Villetaneuse (France))

    1994-10-01

    The work-hardening behavior of mild steel under monotonic deformation at large shears and cyclic deformation under a wide range of shear amplitudes (from 3 to 34%) has been experimentally investigated and modeled. The influence of shear amplitude, the effect of the amount of pre-shear and that of pre-cyclic deformation have been studied. Considering the evolution of both polarized persistent dislocation structures and no-polarized low-energy dislocation configurations, a physically-based phenomenological model with four internal variables has been proposed. The model explains the cyclic hardening behavior at large strains, the work-hardening stagnation followed by a resumption of work-hardening under Bauschinger deformation with large pre-strains and under cyclic deformation with moderate strain amplitudes. A good qualitative and quantitative agreement has been achieved between experimental results and model predictions.

  17. Viscoelastic materials with anisotropic rigid particles: stress-deformation behavior

    NARCIS (Netherlands)

    Sagis, L.M.C.; Linden, van der E.

    2001-01-01

    In this paper we have derived constitutive equations for the stress tensor of a viscoelastic material with anisotropic rigid particles. We have assumed that the material has fading memory. The expressions are valid for slow and small deformations from equilibrium, and for systems that are nearly

  18. Effect of deformation temperature on the hot compressive behavior of metal matrix composites with misaligned whiskers

    Institute of Scientific and Technical Information of China (English)

    LI Aibin; MENG Qingyuan; GENG Lin; DENG Chunfeng; YAN Yiwu

    2007-01-01

    A multi-inclusion cell model is used to investigate the effect of deformation temperature and whisker rotation on the hot compressive behavior of metal matrix composites with misaligned whiskers. Numerical results show that deformation temperature influences the work-hardening behavior of the matrix and the rotation behavior of the whiskers. With increasing temperature, the work hardening rate of the matrix decreases, but the whisker rotation angle increases. Both whisker rotation and the increase of deformation temperature can induce reductions in the load supported by whisker and the load transferred from matrix to whisker. Additionally, it is found that during large strain deformation at higher temperatures, the enhancing of deformation temperature can reduce the effect of whisker rotation. Meanwhile, the stress-strain behavior of the composite is rather sensitive to deformation temperature. At a relatively lower temperature (150℃), the composite exhibits work hardening due to the matrix work hardening, but at relatively higher temperatures (300℃ and above),the composite shows strain softening due to whisker rotation. It is also found that during hot compression at higher temperatures, the softening rate of the composite decreases with increasing temperature. The predicted stress-strain behavior of the composite is approximately in agreement with the experimental results.

  19. Connecting grain-scale physics to macroscopic granular flow behavior using discrete contact-dynamics simulations, centrifuge experiments, and continuum modeling

    Science.gov (United States)

    Reitz, Meredith; Stark, Colin; Hung, Chi-Yao; Smith, Breannan; Grinspin, Eitan; Capart, Herve; Li, Liming; Crone, Timothy; Hsu, Leslie; Ling, Hoe

    2014-05-01

    A complete theoretical understanding of geophysical granular flow is essential to the reliable assessment of landslide and debris flow hazard and for the design of mitigation strategies, but several key challenges remain. Perhaps the most basic is a general treatment of the processes of internal energy dissipation, which dictate the runout velocity and the shape and scale of the affected area. Currently, dissipation is best described by macroscopic, empirical friction coefficients only indirectly related to the grain-scale physics. Another challenge is describing the forces exerted at the boundaries of the flow, which dictate the entrainment of further debris and the erosion of cohesive surfaces. While the granular effects on these boundary forces have been shown to be large compared to predictions from continuum approximations, the link between granular effects and erosion or entrainment rates has not been settled. Here we present preliminary results of a multi-disciplinary study aimed at improving our understanding of granular flow energy dissipation and boundary forces, through an effort to connect grain-scale physics to macroscopic behaviors. Insights into grain-scale force distributions and energy dissipation mechanisms are derived from discrete contact-dynamics simulations. Macroscopic erosion and flow behaviors are documented from a series of granular flow experiments, in which a rotating drum half-filled with grains is placed within a centrifuge payload, in order to drive effective gravity levels up to ~100g and approach the forces present in natural systems. A continuum equation is used to characterize the flowing layer depth and velocity resulting from the force balance between the down-slope pull of gravity and the friction at the walls. In this presentation we will focus on the effect of granular-specific physics such as force chain networks and grain-grain collisions, derived from the contact dynamics simulations. We will describe our efforts to

  20. Deformation and fatigue behaviors of carburized automotive gear steel and predictions

    Directory of Open Access Journals (Sweden)

    Bonglae Jo

    2016-07-01

    Full Text Available The fatigue behavior of carburized components such as automotive transmission gears is very complex due to hardness and microstructure difference, residual stresses and multi-axial stress states developed between the case and the core. In addition, automotive gears in service, commonly used in helical type, are actually subjected to complex stress conditions such as bending, torsion, and contact stress states. This study presents experimental and analytical results on deformation behavior of carburized steels, widely used in automotive gears, under cyclic stress conditions including axial and torsion loadings. Axial fatigue tests and rotating bending fatigue tests are also included. Predictions of cyclic deformation and fatigue behaviors of the carburized steel with two-layer model are compared with experimental results. The carburized steel investigated in this study exhibited cyclic softening under both axial loading and torsional loading. Predicted results with simple two-layer model for the cyclic deformation and fatigue behaviors were comparatively similar to the experimental data.

  1. Experimental Investigation on Creep Deformation Behavior of Medium-strength Marble Rock

    Directory of Open Access Journals (Sweden)

    Li Yong

    2014-01-01

    Full Text Available The creep deformation behavior of rocks has significant effect on the stability of underground structures. This study presents the short-term and creep deformation behavior of medium-strength marble rock using a conventional uniaxial compression testing machine and a servo-controlled rheology testing machine. The uniaxial compressive strength is obtained by the uniaxial compression testing machine. During the creep behavior test, two types of rock specimens (dry and water-saturated are specified to be used to perform the uniaxial creep tests. Two rheological failure modes and the relationship curves between axial/circumferential strain and stress levels of marble specimens are also obtained from the creep test results. Eventually, the creep deformation behaviors are compared with those of typical soft rocks. These creep curves combined with a given creep constitutive model would provide accurate parameters for long-term stability analyses of actual projects.

  2. PLASTIC DEFORMATION BEHAVIOR OF ELECTROFORMED COPPER LINER OF SHAPED CHARGE AT DIFFERENT STRAIN RATES

    Institute of Scientific and Technical Information of China (English)

    H.Y. Gao; W.H. Tian; A.L. Fan; Q. Sun

    2003-01-01

    The paper deals with different plastic deformation behavior of electroformed copperliner of shaped charge, deformed at high strain rate (about 1×107 s-1) and normalstrain rate (4×10-4 s-1). The crystallographic orientation distribution of grains inrecovered slugs which had undergone high-strain-rate plastic deformation during ex-plosive detonation was investigated by electron backscattering Kikuchi pattern tech-nique. Cellular structures formed by tangled dislocations and sub-grain boundariesconsisting of dislocation arrays were detected in the recovered slugs. Some twins andslip dislocations were observed in specimen deformed at normal strain rate. It wasfound that dynamic recovery and recrystallization take place during high-strain-ratedeformation due to the temperature rising, whereas the conventional slip mechanismoperates during deformation at normal strain rate.

  3. PLASTIC DEFORMATION BEHAVIOR OF ELECTROFORMED COPPER LINER OF SHAPED CHARGE AT DIFFERENT STRAIN RATES

    Institute of Scientific and Technical Information of China (English)

    H.Y.Gao; Q.Sun

    2003-01-01

    The paper deals with different plastic deformation behavior of electroformed copper liner of shaped charge,depormed at high strain rate(about 1×107s-1) and normal strain rate (4×10-4s-1).The crystallographic orientation distribution of grains in recovered slugs which had undergone high-strain-rate plastic deformation during ex-plosive detonation was investigated by electron backscattering Kikuchi pattern tech-nique.Cellualar structures formed by tangled disocations and sub-grain boundaries consisting of dislocation arrays were detected in the recovered slugs.Some twins and slip dislocations were observed in specimen deformed at normal strain rate.It was found that dynamic recovery and recrystallization take place during high-strain-rate deformation due to the temperature rising,whereas the conventional slip mechanism operates during deformation at normal strain rate.

  4. Deformation behavior of duplex austenite and ε-martensite high-Mn steel

    Directory of Open Access Journals (Sweden)

    Ki Hyuk Kwon, Byeong-Chan Suh, Sung-Il Baik, Young-Woon Kim, Jong-Kyo Choi and Nack J Kim

    2013-01-01

    Full Text Available 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.

  5. Long-Time Behavior of Macroscopic Quantum Systems: Commentary Accompanying the English Translation of John von Neumann's 1929 Article on the Quantum Ergodic Theorem

    CERN Document Server

    Goldstein, Sheldon; Tumulka, Roderich; Zanghi, Nino

    2010-01-01

    The renewed interest in the foundations of quantum statistical mechanics in recent years has led us to study John von Neumann's 1929 article on the quantum ergodic theorem. We have found this almost forgotten article, which until now has been available only in German, to be a treasure chest, and to be much misunderstood. In it, von Neumann studied the long-time behavior of macroscopic quantum systems. While one of the two theorems announced in his title, the one he calls the "quantum H-theorem", is actually a much weaker statement than Boltzmann's classical H-theorem, the other theorem, which he calls the "quantum ergodic theorem", is a beautiful and very non-trivial result. It expresses a fact we call "normal typicality" and can be summarized as follows: For a "typical" finite family of commuting macroscopic observables, every initial wave function $\\psi_0$ from a micro-canonical energy shell so evolves that for most times $t$ in the long run, the joint probability distribution of these observables obtained ...

  6. Effect of deformation temperature and strain rate on semi-solid deformation behavior of spray-formed Al-70 %Si alloys

    Institute of Scientific and Technical Information of China (English)

    ZHANG Di; YANG Bin; ZHANG Ji-shan; ZHANG Yong-an; XIONG Bai-qing

    2005-01-01

    Spray-formed Al-70%Si(mass fraction) alloys were deformed by compression in the semi-solid state.The effects of the deformation temperature, strain rate and the microstructure were studied. Two strain rates(1 s-1and 0.1 s-1) and six deformation temperatures (600 ℃, 720 ℃ , 780 ℃, 900 ℃, 1 000 ℃ and 1 100 ℃) were chosen. The stress-strain curve exhibits a peak at low strain and then decreases to a plateau before it starts to increase again as the strain increases. The stress required for deformation at lower strain rate and at higher deformation temperatures is less than those at higher strain rate and at lower deformation temperatures. Four mechanisms of semisolid deformation can be used to explain the different behaviors of the stress-strain curves under different conditions.

  7. Deformation behavior of Zr-based bulk metallic glass and composite in the supercooled liquid region

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A Zr-based bulk metallic glass (BMG) with a composition of (Zr75Cu25)78.5Ta4Ni10Al7.5 and a bulk metallic glass matrix composite (BMGC) with a composition of (Zr75Cu25)74.5Ta8Ni10Al7.5 have been prepared by copper-mold casting. The compres-sive deformation behavior of the BMG and BMGC was investigated in the super-cooled region at different temperatures and various strain rates ranging from 8×10-4s-1 to 8×10-2s-1. It was found that both the strain rate and test temperature signifi-cantly affect the deformation behavior of the two alloys. The deformation follows Newtonian flow at low strain rates but non-Newtonian flow at high strain rates. The deformation mechanism for the two kinds of alloys was discussed in terms of the transition state theory.

  8. A Density Functional Theory Study on the Deformation Behaviors of Fe-Si-B Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Guang-Ping Zheng

    2012-08-01

    Full Text Available Density functional theory has been employed to investigate the deformation behaviors of glassy Fe-Si-B model systems prepared by ab initio molecular dynamics. The atomistic deformation defects which are closely related to the local dilation volumes or excess volumes and unstable bonding have been systematically analyzed. It has been found that the icosahedral structures are relatively stable under shear deformation until fracture occurs. Plastic flow is indicated by interruption of percolating icosahedral structures, caused by unstable Fe-Si bonding of p-s hybridization in nature.

  9. Large N behavior of mass deformed ABJM theory

    Science.gov (United States)

    Nosaka, Tomoki; Shimizu, Kazuma; Terashima, Seiji

    2016-03-01

    In this paper, using the localization technique we analyze the large N limit of the mass deformed Aharony-Bergman-Jafferis-Maldacena (ABJM) theory on the three sphere with a finite mass parameter and finite Chern-Simons levels. We find two different solutions of the saddle point equations in the large N limit. With these solutions we compute the free energy limit and find that there is a first order phase transition. Our results may predict a phase transition in the dual gravity theory.

  10. Large N behavior of mass deformed ABJM theory

    CERN Document Server

    Nosaka, Tomoki; Terashima, Seiji

    2015-01-01

    In this paper, using the localization technique we analyze the large N limit of the mass deformed Aharony-Bergman-Jafferis-Maldacena (ABJM) theory on the three sphere with a finite mass parameter and finite Chern-Simons levels. We find two different solutions of the saddle point equations in the large N limit. With these solutions we compute the free energy and find that there is a first order phase transition. Our results may predict a phase transition in the dual gravity theory.

  11. Compression Deformation Behavior of AZ81 Magnesium Alloy at Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Xiaoping Luo

    2014-01-01

    Full Text Available The hot deformation behavior of an AZ81 magnesium alloy was investigated by hot compressive testing on a Gleeble-1500 thermal mechanical simulator in the temperature range from 200 to 400°C and in the strain rate range of 0.001–5 s−1. The relationships among flow stress, strain rate, and deformation temperature were analyzed, and the deformation activation energy and stress exponent were calculated. The microstructure evolution of the AZ81 magnesium alloy under high deformation was examined. The results indicated that the maximum value of the flow stress increased with the decrease of deformation temperature and the increase of strain rate. When the deformation temperature is constant, the flow stress of the AZ81 magnesium alloy increases with the increase of strain rate, which can be demonstrated by a Zener-Hollomon parameter in a hyperbolic-sine-type equation with a hot compression deformation activation energy of 176.01 KJ/mol and basic hot deformation material factors A, n, and a in the analytical expression of the AZ81 magnesium alloy flow stress of 3.21227×1014 s−1, 7.85, and 0.00866 MPa, respectively.

  12. Shear Deformation Behaviors of Sn3.5Ag Lead-free Solder Samples

    Institute of Scientific and Technical Information of China (English)

    Jing Han; Hongtao Chen; Mingyu Li; Chunqing Wang

    2013-01-01

    In this study,shear tests have been performed on the as-reflowed Sn3.5Ag solder bumps and joints to investigate the deformation behavior of Sn3.5Ag lead-free solder samples.Scanning electron microscopy (SEM) was employed to characterize the microstructures of the samples and orientation imaging microscopy (OIM) with electron backscattered diffraction (EBSD) in SEM was used to obtain crystallographic orientation of grains to provide a detailed characterization of the deformation behavior in Sn3.5Ag solder samples after shear tests.The deformation behavior in solder samples under shear stress was discussed.The experimental results suggest that the dynamic recrystallization could occur under shear stress at room temperature and recrystallized grains should evolve from subgrains by rotation.Compared with that of non-recrystallized and as-reflowed microstructures,the microhardness of the recrystallized microstructure decreased after shear tests.

  13. Covariant Macroscopic Quantum Geometry

    CERN Document Server

    Hogan, Craig J

    2012-01-01

    A covariant noncommutative algebra of position operators is presented, and interpreted as the macroscopic limit of a geometry that describes a collective quantum behavior of the positions of massive bodies in a flat emergent space-time. The commutator defines a quantum-geometrical relationship between world lines that depends on their separation and relative velocity, but on no other property of the bodies, and leads to a transverse uncertainty of the geometrical wave function that increases with separation. The number of geometrical degrees of freedom in a space-time volume scales holographically, as the surface area in Planck units. Ongoing branching of the wave function causes fluctuations in transverse position, shared coherently among bodies with similar trajectories. The theory can be tested using appropriately configured Michelson interferometers.

  14. Use of multiscale zirconium alloy deformation models in nuclear fuel behavior analysis

    Energy Technology Data Exchange (ETDEWEB)

    Montgomery, Robert; Tomé, Carlos; Liu, Wenfeng; Alankar, Alankar; Subramanian, Gopinath; Stanek, Christopher

    2017-01-01

    Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. CASL has endeavored to improve upon this approach by incorporating a microstructurally-based, atomistically-informed, zirconium alloy mechanical deformation analysis capability into the BISON-CASL engineering scale fuel performance code. Specifically, the viscoplastic self-consistent (VPSC) polycrystal plasticity modeling approach, developed by Lebensohn and Tome´ [2], has been coupled with BISON-CASL to represent the mechanistic material processes controlling the deformation behavior of the cladding. A critical component of VPSC is the representation of the crystallographic orientation of the grains within the matrix material and the ability to account for the role of texture on deformation. The multiscale modeling of cladding deformation mechanisms allowed by VPSC far exceed the functionality of typical semi-empirical constitutive models employed in nuclear fuel behavior codes to model irradiation growth and creep, thermal creep, or plasticity. This paper describes the implementation of an interface between VPSC and BISON-CASL and provides initial results utilizing the coupled functionality.

  15. Compression deformation behaviors of sheet metals at various clearances and side forces

    Directory of Open Access Journals (Sweden)

    Zhan Mei

    2015-01-01

    Full Text Available Modeling sheet metal forming operations requires understanding of plastic behaviors of sheet metals along non-proportional strain paths. The plastic behavior under reversed uniaxial loading is of particular interest because of its simplicity of interpretation and its application to material elements drawn over a die radius and underwent repeated bending. However, the attainable strain is limited by failures, such as buckling and in-plane deformation, dependent on clearances and side forces. In this study, a finite element (FE model was established for the compression process of sheet specimens, to probe the deformation behavior. The results show that: With the decrease of the clearance from a very large value to a very small value, four defects modes, including plastic t-buckling, micro-bending, w-buckling, and in-plane compression deformation will occur. With the increase of the side force from a very small value to a very large value, plastic t-buckling, w-buckling, uniform deformation, and in-plane compression will occur. The difference in deformation behaviors under these two parameters indicates that the successful compression process without failures for sheet specimens only can be carried out under a reasonable side force.

  16. Dynamic recrystallization behavior of a γ′-hardened nickel-based superalloy during hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongbin; Zhang, Kaifeng [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Jiang, Shaosong, E-mail: jiangshaosong@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhou, Haiping [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhao, Changhong; Yang, Xiaoli [Fushun Special Steel Co. Ltd, Fushun 113000 (China)

    2015-02-25

    Highlights: • The relationship between the peak stress and stable DRX grain size has been expressed by a power law function. • The effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature. • The effect of DDRX became stronger with the increasing strain for the alloy deformed at 1160 °C/0.1 s{sup −1}. • The fraction of twin boundaries is closely related to the deformation temperature and strain. - Abstract: The hot deformation behavior of a γ′-hardened nickel-based superalloy was investigated by means of isothermal compression tests in the temperature range of 1010–1210 °C with a strain rate of 0.1 s{sup −1}. The electron backscatter diffraction (EBSD) technique and transmission electron microscope (TEM) were employed to investigate the effect of deformation temperature and strain on the microstructure evolution and nucleation mechanisms of dynamic recrystallization (DRX). Microstructure observations revealed that the size and volume fraction of DRX grains increased with the increasing temperature. A power exponent relationship was obtained between the stable DRX grain size and the peak stress. Additionally, it was found that the effect of CDRX characterized by progressive subgrain rotation became weaker with the increasing deformation temperature, and DDRX was the operating nucleation mechanism of DRX at higher deformation temperature. On the other hand, the effect of DDRX became stronger with the increasing strain, and CDRX can only be considered as an assistant nucleation mechanism of DRX at the later stage of deformation for the alloy deformed at 1160 °C. Nucleation of DRX can also be activated by the twinning formation. Hence, particular attention was also paid to the evolution of twin boundaries during hot deformation.

  17. Deformation behavior of metallic glass composites reinforced with shape memory nanowires studied via molecular dynamics simulations

    Science.gov (United States)

    Şopu, D.; Stoica, M.; Eckert, J.

    2015-05-01

    Molecular dynamics simulations indicate that the deformation behavior and mechanism of Cu64Zr36 composite structures reinforced with B2 CuZr nanowires are strongly influenced by the martensitic phase transformation and distribution of these crystalline precipitates. When nanowires are distributed in the glassy matrix along the deformation direction, a two-steps stress-induced martensitic phase transformation is observed. Since the martensitic transformation is driven by the elastic energy release, the strain localization behavior in the glassy matrix is strongly affected. Therefore, the composite materials reinforced with a crystalline phase, which shows stress-induced martensitic transformation, represent a route for controlling the properties of glassy materials.

  18. The deformation behavior of soil mass in the subsidence region of Beijing, China

    Science.gov (United States)

    Tian, F.; Liu, J.-R.; Luo, Y.; Zhu, L.; Yang, Y.; Zhou, Y.

    2015-11-01

    Land subsidence induced by excessive groundwater withdrawal has been a major environmental and geological problem in the Beijing plain area. The monitoring network of land subsidence in Beijing has been established since 2002 and has covered the entire plain area by the end of 2008. Based on data from extensometers and groundwater observation wells, this paper establishes curves of variations over time for both soil mass deformation and water levels and the relationship between soil mass deformation and water level. In addition, an analysis of deformation behavior is carried out for soil mass with various lithologies at different depths depending on the corresponding water level. Finally, the deformation behavior of soil mass is generalized into five categories. The conclusions include: (i) the current rate of deformation of the shallow soil mass is slowing, and most of the mid-deep and deep soil mass continue to compress at a more rapid speed; (ii) the sand strata behaves elastically, while the clay soil mass at different depths is usually characterized by elastic-plastic and creep deformation, which can be considered as visco-elastoplastic.

  19. Phase transformation and deformation behavior of NiTi-Nb eutectic joined NiTi wires.

    Science.gov (United States)

    Wang, Liqiang; Wang, Cong; Zhang, Lai-Chang; Chen, Liangyu; Lu, Weijie; Zhang, Di

    2016-04-06

    NiTi wires were brazed together via eutectic reaction between NiTi and Nb powder deposited at the wire contact region. Phase transformation and deformation behavior of the NiTi-Nb eutectic microstructure were investigated using transmission electron microscopy (TEM) and cyclic loading-unloading tests. Results show that R phase and B19' martensite transformation are induced by plastic deformation. R phase transformation, which significantly contributes to superelasticity, preferentially occurs at the interfaces between NiTi and eutectic region. Round-shaped Nb-rich phase with rod-like and lamellar-type eutectics are observed in eutectic regions. These phases appear to affect the deformation behavior of the brazed NiTi-Nb region via five distinct stages in stress-strain curves: (I) R phase reorientation, (II) R phase transformation from parent phase, (III) elastic deformation of reoriented martensite accompanied by the plastic deformation of Nb-rich phase and lamellar NiTi-Nb eutectic, (IV) B19' martensitic transformation, and (V) plastic deformation of the specimen.

  20. Geometrically nonlinear deformation and the emergent behavior of polarons in soft matter.

    Science.gov (United States)

    Li, Xiaobao; Liu, Liping; Sharma, Pradeep

    2015-11-07

    Mechanical strain can alter the electronic structure of both bulk semiconductors as well as nanostructures such as quantum dots. This fact has been extensively researched and exploited for tailoring electronic properties. The strain mediated interaction between the charge carriers and the lattice is interpreted through the so-called deformation potential. In the case of soft materials or nanostructures, such as DNA, the deformation potential leads to the formation of polarons which largely determine the electronic characteristics of DNA and similar polymer entities. In addition, polarons are also speculated to be responsible for the mechanism of quantum actuation in carbon nanotubes. The deformation potential is usually taken to be a linear function of the lattice deformation (U ∼ αε) where α is the deformation potential "constant" that determines the coupling strength and ε is the mechanical strain. In this letter, by carefully accounting for nonlinear geometric deformation that has been hitherto ignored so far in this context, we show that the deformation potential constant is renormalized in a non-trivial manner and is hardly a constant. It varies spatially within the material and with the size of the material. This effect, while negligible for hard materials, is found to be important for soft materials and critically impacts the interpretation of quantities such as polaron size, binding energy, and accordingly, electronic behavior.

  1. Scale-bridging analysis on deformation behavior of high-nitrogen austenitic steels.

    Science.gov (United States)

    Lee, Tae-Ho; Ha, Heon-Young; Hwang, Byoungchul; Kim, Sung-Joon; Shin, Eunjoo; Lee, Jong Wook

    2013-08-01

    Scale-bridging analysis on deformation behavior of high-nitrogen austenitic Fe-18Cr-10Mn-(0.39 and 0.69)N steels was performed by neutron diffraction, electron backscattered diffraction (EBSD), and transmission electron microscopy (TEM). Two important modes of deformation were identified depending on the nitrogen content: deformation twinning in the 0.69 N alloy and strain-induced martensitic transformation in the 0.39 N alloy. The phase fraction and deformation faulting probabilities were evaluated based on analyses of peak shift and asymmetry of neutron diffraction profiles. Semi in situ EBSD measurement was performed to investigate the orientation dependence of deformation microstructure and it showed that the variants of ε martensite as well as twin showed strong orientation dependence with respect to tensile axis. TEM observation showed that deformation twin with a {111} mathematical left angle bracket 112 mathematical right angle bracket crystallographic component was predominant in the 0.69 N alloy whereas two types of strain-induced martensites (ε and α' martensites) were observed in the 0.39 N alloy. It can be concluded that scale-bridging analysis using neutron diffraction, EBSD, and TEM can yield a comprehensive understanding of the deformation mechanism of nitrogen-alloyed austenitic steels.

  2. Study on Hot Deformation Behavior of 7085 Aluminum Alloy during Backward Extrusion Process

    Directory of Open Access Journals (Sweden)

    R. B. Mei

    2015-01-01

    Full Text Available Compression test was carried out and the true stress-strain curves were obtained from the hot compression of 7085 alloy. A numerical simulation on the deformation behavior of 7085 aluminum alloy during the backward extrusion was also performed by finite element method. The results show that dynamic recrystallization occurs in the hot compression of 7085 alloy and the peak stress reaches higher values as the strain rate increases and deformation temperature decreases. The backward extrusion processes include contact deformation, initial deformation, and steady deformation. Severe plastic deformation of shear and compression occurs when the metal flowed into the channel between fillet of punch and wall of die so that the grain size can be refined by backward extrusion. The deformation in the region of top of wall is too small to meet the mechanical properties of requirements and the metal usually needs to be trimmed. The experiments with the same parameters as simulation had been carried out and the experimental cup after extrusion has better quality.

  3. Inflation-predictable behavior and co-eruption deformation at Axial Seamount

    Science.gov (United States)

    Nooner, Scott L.; Chadwick, William W.

    2016-12-01

    Deformation of the ground surface at active volcanoes provides information about magma movements at depth. Improved seafloor deformation measurements between 2011 and 2015 documented a fourfold increase in magma supply and confirmed that Axial Seamount’s eruptive behavior is inflation-predictable, probably triggered by a critical level of magmatic pressure. A 2015 eruption was successfully forecast on the basis of this deformation pattern and marked the first time that deflation and tilt were captured in real time by a new seafloor cabled observatory, revealing the timing, location, and volume of eruption-related magma movements. Improved modeling of the deformation suggests a steeply dipping prolate-spheroid pressure source beneath the eastern caldera that is consistent with the location of the zone of highest melt within the subcaldera magma reservoir determined from multichannel seismic results.

  4. Deformation Behavior of Mg-8 wt%Li Alloy under High-speed Impact

    Institute of Scientific and Technical Information of China (English)

    SHA Gui-ying; LIU Chun-zhong; YU Tao; SHI Ji-hong

    2006-01-01

    Deformation behavior of the Mg-8 wt%Li alloy at high strain rate was studied by means of the Split Hopkinson Pressure Bar (with strain rate of 103 s-1). It is found that shear localization proves to be the main damage mode for the alloy during dynamic loading. Strain and strain rate are the two necessary parameters affecting the occurrence of deformation and shear bands. Deformation bands begin to form when the strain and strain rate reach 0.20 and 1 900 s-1 respectively and will develop gradually with the strain rate increasing. Besides, deformation bands will transform into shear bands when the strain and strain rate reach above 0.25 and 3 500 s-1 separately.

  5. Finite element simulations of deformation behavior in equal channel angular pressing using a rotated die

    Institute of Scientific and Technical Information of China (English)

    Yixuan TAN; Saiyi LI

    2012-01-01

    A new die design for equal channel angular pressing (ECAP) of square cross-section billet was proposed by a 45° rotation of the inlet and outlet channels around the channel axes.ECAP utilizing the rotated and conventional dies was simulated in three dimensions using the finite element method.Conditions with different material properties and friction coefficients were studied.The billet deformation behavior was evaluated in terms of the spatial distribution of equivalent plastic strain,plastic deformation zone and load history.The results show that the rotated die appears to produce billets with a smaller deformation inhomogeneity over the entire crosssection and a greater average of equivalent plastic strain at the cost of a slightly larger working load.The billet deformation enters into a steady state earlier in the case of the rotated die than the conventional die under the condition of a relatively large friction coefficient.

  6. Hot-deformation behaviors of AZ31 alloys with different initial states

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The hot-deformation behaviors of three types of AZ31 samples, extruded sheet, hot rolled sheet and east rod were studied.These samples had different initial grain size and texture. Compression deformation of these samples was carried out using a Gleeble 1500D under a series of thermal deformation conditions. Mierostructure and texture of the initial and deformed samples were examined using electron backscatter diffraction (EBSD) techniques. The flow curves for all these three types of samples shifted upward with strain rate increasing. Significant grain refinement was noticed in the hot rolled sheet sample. The grain size was reduced to 3.7 μm after 50% (ε=0.69) compression. The DRX grains in both the extruded rod and hot rolled sheet samples presented the same basal plane texture, irrespective of the difference in the initial texture of the samples.

  7. Analysis of the deformation behavior of low Cu-Cr-Zr alloy

    Science.gov (United States)

    Morozova, A.; Belyakov, A.; Kaibyshev, R.

    2016-11-01

    Mechanical properties and the microstrustural evolution of low Cu-Cr-Zr alloy subjected to equal channel angular pressing (ECAP) at 400°C via route BC after the solution treatment were investigated. Plastic deformation resulted in the formation of a large number of low-angle subgrain boundaries in initial coarse grains. New fine grains formed due to a progressive increase in misorientations of strain-induced (sub)boundaries. The ultrafine grain formation during large plastic deformation was accompanied by significant strengthening. The variation of the strain hardening rate with the flow stress after the total strain ɛ ˜ 1-12 was studied. The deformation behavior was discussed in terms of the dislocation-density-related Voce equation. Large plastic deformation led to an increase in both the ɛC and ɛV parameters in the Voce equation. The relationship between strain hardening and microstructure is considered in detail using the Voce parameters.

  8. Recrystailization Behavior of Deformed Austenite in High Strength Microalloyed Pipeline Steel

    Institute of Scientific and Technical Information of China (English)

    YANG Jing-hong; LIU Qing-you; SUN Dong-bai; LI Xiang-yang

    2009-01-01

    Using methods of single-hit hot compression and stress relaxation after deformation on a Gleeble 1500D thermomechanical simulator,the curves of flow stress and stress relaxation,the microstructure and the recrystallization behavior of Nb-V-Ti high strength microalloyed low carbon pipeline steel were studied,and the influence of the thermomechanical treatment parameters on dynamic and static recrystallization of the steel was investigated.It was found that microalloying elements improved the deformation activation energy and produced a retardation of the recrystallization due to the solid solution and precipitation pinning.The deformation conditions such as deformation temperature,strain,and strain rate influenced the recrystallization kinetics and the microstructure respectively.Equations obtained can be used to valuate and predict the dynamic and static recrystallizations.

  9. Investigation on Deformation Behavior of Nickel Aluminum Bronze by Neutron Diffraction and Transmission Electron Microscopy

    Science.gov (United States)

    Xu, Xiaoyan; Wang, Hong; Lv, Yuting; Lu, Weijie; Sun, Guangai

    2016-05-01

    The deformation behavior, deformation microstructures, and generated inter-phase stresses of nickel aluminum bronze were investigated by in situ neutron diffraction instrument and transmission electron microscopy in this paper. Lattice strains calculated by both peak shifting and broadening by Gaussian fitting of α and κ phase neutron diffraction peak profiles at both holding stress conditions and unloaded stress conditions were compared. Twining and stacking faults in α matrix were observed after deformed by different tensile stresses. Compressive internal/residual stress in α matrix and tensile internal stress in κ phase in elasto-plastic region were calculated based on neutron diffraction analysis. The piled-up dislocations around hard κ phases increase with increasing the deformation degree, which raise the stress concentration near α/ κ interface and increase the internal stresses.

  10. A macroscopic violation of no-signaling in time inequalities? How to test temporal entanglement with behavioral observables.

    Science.gov (United States)

    Tressoldi, Patrizio E; Maier, Markus A; Buechner, Vanessa L; Khrennikov, Andrei

    2015-01-01

    In this paper we applied for the first time the no-signaling in time (NSIT) formalism discussed by Kofler and Brukner (2013) to investigate temporal entanglement between binary human behavioral unconscious choices at t1 with binary random outcomes at t2. NSIT consists of a set of inequalities and represents mathematical conditions for macro-realism which require only two measurements in time. The analyses of three independent experiments show a strong violation of NSIT in two out of three of them, suggesting the hypothesis of a quantum-like temporal entanglement between human choices at t1 with binary random outcomes at t2. We discuss the potentialities of using NSIT to test temporal entanglement with behavioral measures.

  11. A Macroscopic Violation of No Signaling In Time Inequalities? How to test Temporal Entanglement with Behavioral Observables

    Directory of Open Access Journals (Sweden)

    Patrizio E Tressoldi

    2015-07-01

    Full Text Available In this paper we applied for the first time the no-signaling in time (NSIT formalism discussed by Kofler and Brukner to investigate temporal entanglement between binary human behavioral unconscious choices at t1 with binary random outcomes at t2. NSIT consists of a set of inequalities and represents mathematical conditions for macro-realism which require only two measurements in time. The analyses of three independent experiments show a strong violation of NSIT in two out of three of them, suggesting the hypothesis of a quantum-like temporal entanglement between human choices at t1 with binary random outcomes at t2. We discuss the potentialities of using NSIT to test temporal entanglement with behavioral measures.

  12. The consequences of dependence between the formal area efficiency and the macroscopic electric field on linearity behavior in Fowler-Nordheim plots

    Science.gov (United States)

    de Assis, Thiago A.; Dall'Agnol, Fernando F.; Andrade, Roberto F. S.

    2016-09-01

    This work presents a theoretical explanation for a crossover in the linear behavior in Fowler-Nordheim (FN) plots based on orthodox cold field electron emission (CFE) experimental data. It is characterized by a clear change in the decay rate of usually single-slope FN plots, and has been reported when non-uniform nano-emitters are subject to high macroscopic electric field F M. We assume that the number of emitting spots, which defines an apparent formal area efficiency of CFE surfaces, depends on the macroscopic electric field. Non-uniformity is described by local enhancement factors ≤ft\\{{γj}\\right\\} , which are randomly assigned to each distinct emitter of a conducting CFE surface, from a discrete probability distribution ρ ≤ft({γj}\\right) , with j  =  1, 2. It is assumed that ρ ≤ft({γ1}\\right)right) , and that {γ1}>{γ2} . The local current density is evaluated by considering a usual Schottky-Nordheim barrier. The results reproduce the two distinct slope regimes in FN plots when {{F}\\text{M}}\\in [2, 20] V μm-1 and are analyzed by taking into account the apparent formal area efficiency, the distribution ρ, and the slopes in the corresponding FN plot. Finally, we remark that our results from numerical solution of Laplace’s equation, for an array of conducting nano-emitters with uniform apex radii 50 nm but different local height, supports our theoretical assumptions and could used in orthodox CFE experiments to test our predictions.

  13. Influence of deformation behavior, oxydation, and temperature on the long time cyclic stress behavior of high temperature steels

    Science.gov (United States)

    Maile, K.

    1982-01-01

    The influence of different parameters on the creep-fatigue behavior of several steel alloys was investigated. The higher the temperature the lower the crack initiation value. Pauses during the cycle reduce the damage. Oxidation reduces and protective gas increases the lifetime. Prior loading and prior deformation reduce the lifetime. Short annealing slightly affects the cycle stress behavior. The test results do not satisfactorily agree with methods of extrapolation and damage accumulation.

  14. Stored energy and annealing behavior of heavily deformed aluminium

    DEFF Research Database (Denmark)

    Kamikawa, Naoya; Huang, Xiaoxu; Kondo, Yuka

    2012-01-01

    followed by 0.5 h annealing at 200-600°C, where the former treatment leads to discontinuous recrystallization and the latter to uniform structural coarsening. This behavior has been analyzed in terms of the relative change during annealing of energy stored as elastic energy in the dislocation structure...... and as boundary energy in the high-angle boundaries. © (2012) Trans Tech Publications, Switzerland....

  15. New Developments in Macroscopic Behavioral Economics and Its Applications%宏观行为经济学的新发展及其应用

    Institute of Scientific and Technical Information of China (English)

    张继海

    2015-01-01

    Neoclassical macroeconomics constitutes the main body of modern mainstream macroeconomics, but it faces many challenges in explaining economic reality. Macroscopic behavioral economics corrects neocla-ssical macroeconomics in its strong assumption that people have unlimited rationality, and enhances the ability to explain economic reality through the introduction of the psychological and social factors which emphasize that people only have limited rationality or rational approximation in face of uncertainty and intertemporal choices. The new developments of macroscopic behavioral economics lie in its research scope and research methods. In terms of research scope, it emphasizes that human preference is not independent or steady, but affected by psychological factors and the like. In terms of research methods, it is no longer confined to experimentation, but adopts various methods and learns from those applied in other economic and psychological fields. It places more emphasis on practical orientation, and the study of “how people actually make decisions”. Its achievements in application include consumer behavior theory and the new explanation of wage and price rigidity. Macroscopic behavioral economics is also inspirational to judging and determining China's macroeconomic policies.%现代主流宏观经济学主体是新古典主义宏观经济学,但在解释经济现实方面其面临诸多挑战。而宏观行为经济学修正新古典主义宏观经济学关于人具有无限理性的强假设,通过引入心理因素和社会因素等强调人们在面对不确定性和跨期选择时只具有有限理性或近似理性,以增强对经济现实的解释能力。宏观行为经济学的新发展主要包括研究内容和研究方法,在研究内容方面强调人们的偏好不是独立的、稳定的,会受到心理因素等影响;在研究方法方面不再局限于试验研究方法,开始广泛采用和借鉴其他经济学领域和心

  16. Constitutive Modeling for Flow Behaviors of Superaustenitic Stainless Steel S32654 during Hot Deformation

    Institute of Scientific and Technical Information of China (English)

    En-xiang PU; Han FENG; Min LIU; Wen-jie ZHENG; Han DONG; Zhi-gang SONG

    2016-01-01

    Hot deformation behavior of superaustenitic stainless steel S32654 was investigated with hot compression tests at temperatures of 950-1 250 ℃ and strain rates of 0�001-10 s-1 .Above 1 150 ℃,with strain rate lower than 0�1 s-1 ,the flow curves exhibit nearly steady-state behavior,while at higher strain rate,continuous flow softening occurs.To provide a precise prediction of flow behavior for the alloy,the constitutive modeling considering effect of strain was derived on the basis of the obtained experimental data and constitutive relationship which incorporated Ar-rhenius term and hyperbolic-sine type equation.The material constantsα,n,Q and lnA are found to be functions of the strain and can be fitted employing eighth-order polynomial.The developed constitutive model can be employed to describe the deformation behavior of superaustenitic stainless steel S32654.

  17. RHEOLOGICAL DEFORMATION BEHAVIOR MODEL OF SUGAR DOUGH IN THE CONDITIONS OF MONOAXIAL COMPRESSION

    Directory of Open Access Journals (Sweden)

    G. O. Magomedov

    2014-01-01

    Full Text Available Summary. The knowledge of regularities of deformation behavior of the processed confectionery masses with certain rheological properties allows to calculate parameters of shaping process and to select processing equipment for its carrying out. The article studies the obtaining of the rheological equation of deformation behavior of sugar dough in the conditions of monoaxial compression which is realized in sugar cookies dough pieces formation processes. The results of the pilot studies confirming adequacy of the offered rheological equation are presented. The behavior of an elastic-, viscous- and plastic body in the conditions of quasistatic test for creeping during which the set size is tension, and the measured one is relative deformation is considered. The main rheological properties of sugar dough received experimentally are given. Values of rheological constants are received and it is revealed that at 95% confidential probability, the rheological equation for the general deformation of an elastic-, viscous- and plastic body adequately describes experimental data. The maximum fault thus makes 2,3%. It is established that dough pieces shaping processes from the sugar dough possessing visco- and plastic properties should be realized at an external tension (power impact from the forming body which exceeds a limit of fluidity of the dough formed. The level of external tension, as well as the duration of its influence (that is formation duration should be chosen taking into account the residual deformations in the processed mass which guarantee giving of a certain geometrical form and drawing on a surface of dough pieces. The rheological model of sugar dough allows to predict its deformation behavior in the formation conditions, and to calculate the parameters of sugar dough formation process.

  18. Role of B19' martensite deformation in stabilizing two-way shape memory behavior in NiTi

    Science.gov (United States)

    Benafan, O.; Padula, S. A.; Noebe, R. D.; Sisneros, T. A.; Vaidyanathan, R.

    2012-11-01

    Deformation of a B19' martensitic, polycrystalline Ni49.9Ti50.1 (at. %) shape memory alloy and its influence on the magnitude and stability of the ensuing two-way shape memory effect (TWSME) was investigated by combined ex situ mechanical experimentation and in situ neutron diffraction measurements at stress and temperature. The microstructural changes (texture, lattice strains, and phase fractions) during room-temperature deformation and subsequent thermal cycling were captured and compared to the bulk macroscopic response of the alloy. With increasing uniaxial strain, it was observed that B19' martensite deformed by reorientation and detwinning with preferred selection of the (1¯50)M and (010)M variants, (201¯)B19' deformation twinning, and dislocation activity. These mechanisms were indicated by changes in bulk texture from the neutron diffraction measurements. Partial reversibility of the reoriented variants and deformation twins was also captured upon load removal and thermal cycling, which after isothermal deformation to strains between 6% and 22% resulted in a strong TWSME. Consequently, TWSME functional parameters including TWSME strain, strain reduction, and transformation temperatures were characterized and it was found that prior martensite deformation to 14% strain provided the optimum condition for the TWSME, resulting in a stable two-way shape memory strain of 2.2%. Thus, isothermal deformation of martensite was found to be a quick and efficient method for creating a strong and stable TWSME in Ni49.9Ti50.1.

  19. Hot deformation behavior of KFC copper alloy during compression at elevated temperatures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; ZHANG Hong-gang; PENG Da-shu

    2006-01-01

    The hot deformation behavior of a KFC copper alloy was studied by compression deformation tests on Gleeble 1500 machine at strain rates ranging between 0.01-10 s-1 and deformation temperature of 650-850 ℃, and associated structural changes were studied by observations of metallography and TEM. The results show that the true stress-true strain curves for a KFC copper alloy are characterized by multiple peaks or a single peak flow, and tend to a steady state at high strains. The peak stress can be represented by a Zener-Hollomon parameter in the hyperbolic-sine-type equation with the hot deformation activation energy Q of 289 kJ/mol. The dynamic recrystallization(DRX) occurs by bulging out of part serrated grain-boundary, and the dynamic recrystallization grain size is dependent sensitively on deformation temperature T and strain rate ε, also a function of Z. The dynamic spherical Fe-rich precipitates and successive dynamic particles coarsening has been assumed to be responsible for flow softening at high strains, and this is more effective when samples deformed at low temperatures and higher strain rates.

  20. Effects of Compression Parameters on Deformation Behaviors of Semi-Solid ZA27 Alloys

    Institute of Scientific and Technical Information of China (English)

    CHEN Ti-jun; HAO Yuan; SUN Jun

    2003-01-01

    An investigation was performed on the effects of semi-solid compression parameters,such as strain rate,compression temperature and heating time at these temperatures on deformation behaviors of two kinds of ZA27 alloys,one was modified by Zr and the other was unmodified.The results indicate that with the increasing of the strain,the stress of the modified composite first sharply increases to a peak value,then dramatically decreases to a plateau value,and again increases till the end of deformation.But for the unmodified,after being up to a peak value,the stress only decreases slowly.As the compression temperature or the heating time decreases,or the strain rate increases,the stress level and the cracking degree of these two kinds of alloys increase.Under the same deformation conditions,the stress level and the cracking degree of the unmodified alloy are higher than those of the modified one.But there is an exception that the stress level of the unmodified alloy is minimum and smaller than that of the modified one when deformed at the low temperature of 450℃.These phenomena were mainly discussed through analyzing the microstructures under different conditions and the deformation mechanisms at different deformation stages.

  1. Use of multiscale zirconium alloy deformation models in nuclear fuel behavior analysis

    Science.gov (United States)

    Montgomery, Robert; Tomé, Carlos; Liu, Wenfeng; Alankar, Alankar; Subramanian, Gopinath; Stanek, Christopher

    2017-01-01

    Accurate prediction of cladding mechanical behavior is a key aspect of modeling nuclear fuel behavior, especially for conditions of pellet-cladding interaction (PCI), reactivity-initiated accidents (RIA), and loss of coolant accidents (LOCA). Current approaches to fuel performance modeling rely on empirical constitutive models for cladding creep, growth and plastic deformation, which are limited to the materials and conditions for which the models were developed. To improve upon this approach, a microstructurally-based zirconium alloy mechanical deformation analysis capability is being developed within the United States Department of Energy Consortium for Advanced Simulation of Light Water Reactors (CASL). Specifically, the viscoplastic self-consistent (VPSC) polycrystal plasticity modeling approach, developed by Lebensohn and Tomé [1], has been coupled with the BISON engineering scale fuel performance code to represent the mechanistic material processes controlling the deformation behavior of light water reactor (LWR) cladding. A critical component of VPSC is the representation of the crystallographic nature (defect and dislocation movement) and orientation of the grains within the matrix material and the ability to account for the role of texture on deformation. A future goal is for VPSC to obtain information on reaction rate kinetics from atomistic calculations to inform the defect and dislocation behavior models described in VPSC. The multiscale modeling of cladding deformation mechanisms allowed by VPSC far exceed the functionality of typical semi-empirical constitutive models employed in nuclear fuel behavior codes to model irradiation growth and creep, thermal creep, or plasticity. This paper describes the implementation of an interface between VPSC and BISON and provides initial results utilizing the coupled functionality.

  2. Modeling the deformation behavior of nanocrystalline alloy with hierarchical microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongxi; Zhou, Jianqiu, E-mail: zhouj@njtech.edu.cn [Nanjing Tech University, Department of Mechanical Engineering (China); Zhao, Yonghao, E-mail: yhzhao@njust.edu.cn [Nanjing University of Science and Technology, Nanostructural Materials Research Center, School of Materials Science and Engineering (China)

    2016-02-15

    A mechanism-based plasticity model based on dislocation theory is developed to describe the mechanical behavior of the hierarchical nanocrystalline alloys. The stress–strain relationship is derived by invoking the impeding effect of the intra-granular solute clusters and the inter-granular nanostructures on the dislocation movements along the sliding path. We found that the interaction between dislocations and the hierarchical microstructures contributes to the strain hardening property and greatly influence the ductility of nanocrystalline metals. The analysis indicates that the proposed model can successfully describe the enhanced strength of the nanocrystalline hierarchical alloy. Moreover, the strain hardening rate is sensitive to the volume fraction of the hierarchical microstructures. The present model provides a new perspective to design the microstructures for optimizing the mechanical properties in nanostructural metals.

  3. Investigation on the viscoelastic behaviors of a circular dielectric elastomer membrane undergoing large deformation

    Directory of Open Access Journals (Sweden)

    Bing Wang

    2016-12-01

    Full Text Available To explore the time-dependent dissipative behaviors of a circular dielectric elastomer membrane subject to force and voltage, a viscoelastic model is formulated based on the nonlinear theory for dissipative dielectrics. The circular membrane is attached centrally to a light rigid disk and then connected to a fixed rigid ring. When subject to force and voltage, the membrane deforms into an out-of plane shape, undergoing large deformation. The governing equations to describe the large deformation are derived by using energy variational principle while the viscoelasticity of the membrane is describe by a two-unit spring-dashpot model. The evolutions of the considered variables and the deformed shape are illustrated graphically. In calculation, the effects of the voltage and the pre-stretch on the electromechanical behaviors of the membrane are examined and the results show that they significantly influence the electromechanical behaviors of the membrane. It is expected that the present model may provide some guidelines in the design and application of such dielectric elastomer transducers.

  4. Deformation behavior of a high strength multiphase steel at macro- and micro-scales

    Energy Technology Data Exchange (ETDEWEB)

    Diego-Calderón, I. de, E-mail: irenedediego.calderon@imdea.org [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain); Santofimia, M.J. [Department of Materials Science and Engineering, Delft University of Technology, 2628 CD Delft (Netherlands); Molina-Aldareguia, J.M.; Monclús, M.A.; Sabirov, I. [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain)

    2014-08-12

    Advanced high strength steels via quenching and partitioning (Q and P) process are a mainstream trend in modern steel research. This work contributes to a better understanding of their local mechanical properties and local deformation behavior at the micro-scale in relation to their local microstructure. A low alloyed steel was subjected to Q and P heat treatments leading to the formation of complex multiphase microstructures. Nanoindentation tests were performed to measure nanohardness of individual phases and to generate 2D maps showing nanohardness distribution on the surface of the material. To study local in-plane plastic strain distribution during deformation, in situ tensile tests were carried out using the digital image correlation technique. Significant partitioning of plastic strain between phase microconstituents during tensile deformation is shown. The effect of the microstructure on the mechanical behavior of the Q and P processed steel is analyzed. The local plastic deformation behavior of individual phases is discussed with respect to their strength and their spatial orientation.

  5. Investigation on the viscoelastic behaviors of a circular dielectric elastomer membrane undergoing large deformation

    Science.gov (United States)

    Wang, Bing; Wang, Zhengang; He, Tianhu

    2016-12-01

    To explore the time-dependent dissipative behaviors of a circular dielectric elastomer membrane subject to force and voltage, a viscoelastic model is formulated based on the nonlinear theory for dissipative dielectrics. The circular membrane is attached centrally to a light rigid disk and then connected to a fixed rigid ring. When subject to force and voltage, the membrane deforms into an out-of plane shape, undergoing large deformation. The governing equations to describe the large deformation are derived by using energy variational principle while the viscoelasticity of the membrane is describe by a two-unit spring-dashpot model. The evolutions of the considered variables and the deformed shape are illustrated graphically. In calculation, the effects of the voltage and the pre-stretch on the electromechanical behaviors of the membrane are examined and the results show that they significantly influence the electromechanical behaviors of the membrane. It is expected that the present model may provide some guidelines in the design and application of such dielectric elastomer transducers.

  6. Interference of macroscopic superpositions

    CERN Document Server

    Vecchi, I

    2000-01-01

    We propose a simple experimental procedure based on the Elitzur-Vaidman scheme to implement a quantum nondemolition measurement testing the persistence of macroscopic superpositions. We conjecture that its implementation will reveal the persistence of superpositions of macroscopic objects in the absence of a direct act of observation.

  7. Deformation Behavior of Recycled Concrete Aggregate during Cyclic and Dynamic Loading Laboratory Tests

    Directory of Open Access Journals (Sweden)

    Wojciech Sas

    2016-09-01

    Full Text Available Recycled concrete aggregate (RCA is a relatively new construction material, whose applications can replace natural aggregates. To do so, extensive studies on its mechanical behavior and deformation characteristics are still necessary. RCA is currently used as a subbase material in the construction of roads, which are subject to high settlements due to traffic loading. The deformation characteristics of RCA must, therefore, be established to find the possible fatigue and damage behavior for this new material. In this article, a series of triaxial cyclic loading and resonant column tests is used to characterize fatigue in RCA as a function of applied deviator stress after long-term cyclic loading. A description of the shakedown phenomenon occurring in the RCA and calculations of its resilient modulus (Mr as a function of fatigue are also presented. Test result analysis with the stress-life method on the Wohler S-N diagram shows the RCA behavior in accordance with the Basquin law.

  8. Low Cycle Fatigue Behavior of 316LN Stainless Steel Alloyed with Varying Nitrogen Content. Part I: Cyclic Deformation Behavior

    Science.gov (United States)

    Prasad Reddy, G. V.; Sandhya, R.; Sankaran, S.; Mathew, M. D.

    2014-10-01

    In this study, the influence of cyclic strain amplitude on the evolution of cyclic stress-strain response and the associated cyclic deformation mechanisms in 316LN stainless steel with varying nitrogen content (0.07 to 0.22 wt pct) is reported in the temperature range 773 K to 873 K (500 °C to 600 °C). Two mechanisms, namely dynamic strain aging and secondary cyclic hardening, are found to strongly influence the cyclic stress response. Deformation substructures associated with both the mechanisms showed planar mode of deformation. These mechanisms are observed to be operative over certain combinations of temperature and strain amplitude. For strain amplitudes >0.6 pct, wavy or mixed mode of deformation is noticed to suppress both the mechanisms. Cyclic stress-strain curves revealed both single and dual-slope behavior depending on the test temperature. Increase in nitrogen content is found to increase the tendency toward planar mode of deformation, while increase in strain amplitude leads to transition from planar slip bands to dislocation cell/wall structure formation, irrespective of the nitrogen content in 316LN stainless steel.

  9. Tensile behavior of Sn-0.7Cu with Zn addition at various deformation temperatures

    Institute of Scientific and Technical Information of China (English)

    Zhongbing LUO; Jie ZHAO; Junshan ZHANG; Lai WANG

    2011-01-01

    The tensile behavior of Sn-0.7Cu and Sn-0.7Cu-lZn was compared at various deformation temperatures. Refined microstructure and γ-CuZn particles were discovered with Zn addition. The strengths of Zn-containing solder were higher than that of Sn-0.7Cu at room and subzero temperatures. With the elevation of deformation temperature, they both decreased and they were nearly the same at 80 ℃. The works of fracture exhibited the similar evolution law. For Sn-0.7Cu solder, the elongation after fracture was smaller and the reduction of area was bigger than those of Sn-0.7Cu-1Zn. This shows that Zn addition improved the deformation stability, which is attributed to the modification of the microstructure. Dimples in fracture surface became smaller and shallower with the decreasing temperature. Ductile fracture was discovered in all the samples.

  10. Altering strength and plastic deformation behavior via alloying and laminated structure in nanocrystalline metals

    Energy Technology Data Exchange (ETDEWEB)

    Gu, C. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Wang, F., E-mail: wangfei@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Huang, P., E-mail: huangping@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China); Lu, T.J. [State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi' an Jiaotong University, Xi' an 710049 (China); MOE Key Laboratory for Multifunctional Materials and Structures, Xi' an Jiaotong University, Xi' an 710049 (China); Xu, K.W. [State Key Laboratory for Mechanical Behavior of Material, Xi' an Jiaotong University, Xi' an 710049 (China)

    2015-07-29

    Nanoindentation and electron microscope techniques have been performed on sputtering deposited monolayered nanocrystalline CuNb and multilayered CuNb/Cu thin films. Microstructural features, hardness and surface morphologies of residual indentation have been evaluated to identify the effects of alloying and laminated structure on strength and plastic deformation behavior of nanocrystalline metals. By altering the content of Nb in CuNb alloy and adding crystalline Cu layers into CuNb alloy, the volume fraction of amorphous phase in CuNb alloy and interface structures changed dramatically, resulting in various trends that are related to hardness, indentation induced pileup and shear banding deformation. Based on the experimental results, the dominant deformation mechanisms of the CuNb and CuNb/Cu thin films with various Nb contents were proposed and extended to be discussed.

  11. Crack Coalescence in Molded Gypsum and Carrara Marble: Part 1. Macroscopic Observations and Interpretation

    Science.gov (United States)

    Wong, L. N. Y.; Einstein, H. H.

    2009-06-01

    Cracking and coalescence behavior has been studied experimentally with prismatic laboratory-molded gypsum and Carrara marble specimens containing two parallel pre-existing open flaws. This was done at both the macroscopic and the microscopic scales, and the results are presented in two separate papers. This paper (the first of two) summarizes the macroscopic experimental results and investigates the influence of the different flaw geometries and material, on the cracking processes. In the companion paper (also in this issue), most of the macroscopic deformation and cracking processes shown in this present paper will be related to the underlying microscopic changes. In the present study, a high speed video system was used, which allowed us to precisely observe the cracking mechanisms. Nine crack coalescence categories with different crack types and trajectories were identified. The flaw inclination angle ( β), the ligament length ( L), that is, intact rock length between the flaws, and the bridging angle ( α), that is, the inclination of a line linking up the inner flaw tips, between two flaws, had different effects on the coalescence patterns. One of the pronounced differences observed between marble and gypsum during the compression loading test was the development of macroscopic white patches prior to the initiation of macroscopic cracks in marble, but not in gypsum. Comparing the cracking and coalescence behaviors in the two tested materials, tensile cracking generally occurred more often in marble than in gypsum for the same flaw pair geometries.

  12. Hot Deformation Behavior and Dynamic Recrystallization of Medium Carbon LZ50 Steel

    Science.gov (United States)

    Du, Shiwen; Chen, Shuangmei; Song, Jianjun; Li, Yongtang

    2017-01-01

    Hot deformation and dynamic recrystallization behaviors of a medium carbon steel LZ50 were systematically investigated in the temperature range from 1143 K to 1443 K (870 °C to 1170 °C) at strain rates from 0.05 to 3s-1 using a Gleeble-3500 thermo-simulation machine. The flow stress constitutive equation for hot deformation of this steel was developed with the two-stage Laasraoui equation. The activation energy of the tested steel was 304.27 KJ/mol, which was in reasonable agreement with those reported previously. The flow stress of this steel in hot deformation was mainly controlled by dislocation climb during their intragranular motion. The effect of Zener-Hollomon parameter on the characteristic points of the flow curves was studied, and the dependence of critical strain on peak strain obeyed a linear equation. Dynamic recrystallization was the most important softening mechanism for the tested steel during hot deformation. Kinetic equation of this steel was also established based on the flow stress. The austenite grain size of complete dynamic recrystallization was a power law function of Zener-Hollomon parameter with an exponent of -0.2956. Moreover, the microstructures induced under different deformation conditions were analyzed.

  13. Hot Deformation Behavior and Dynamic Recrystallization of Medium Carbon LZ50 Steel

    Science.gov (United States)

    Du, Shiwen; Chen, Shuangmei; Song, Jianjun; Li, Yongtang

    2017-03-01

    Hot deformation and dynamic recrystallization behaviors of a medium carbon steel LZ50 were systematically investigated in the temperature range from 1143 K to 1443 K (870 °C to 1170 °C) at strain rates from 0.05 to 3s-1 using a Gleeble-3500 thermo-simulation machine. The flow stress constitutive equation for hot deformation of this steel was developed with the two-stage Laasraoui equation. The activation energy of the tested steel was 304.27 KJ/mol, which was in reasonable agreement with those reported previously. The flow stress of this steel in hot deformation was mainly controlled by dislocation climb during their intragranular motion. The effect of Zener-Hollomon parameter on the characteristic points of the flow curves was studied, and the dependence of critical strain on peak strain obeyed a linear equation. Dynamic recrystallization was the most important softening mechanism for the tested steel during hot deformation. Kinetic equation of this steel was also established based on the flow stress. The austenite grain size of complete dynamic recrystallization was a power law function of Zener-Hollomon parameter with an exponent of -0.2956. Moreover, the microstructures induced under different deformation conditions were analyzed.

  14. Deformation behavior of metallic glasses with shear band like atomic structure: a molecular dynamics study.

    Science.gov (United States)

    Zhong, C; Zhang, H; Cao, Q P; Wang, X D; Zhang, D X; Ramamurty, U; Jiang, J Z

    2016-08-02

    Molecular dynamics simulations were employed to investigate the plastic deformation within the shear bands in three different metallic glasses (MGs). To mimic shear bands, MG specimens were first deformed until flow localization occurs, and then the volume of the material within the localized regions was extracted and replicated. Homogeneous deformation that is independent of the size of the specimen was observed in specimens with shear band like structure, even at a temperature that is far below the glass transition temperature. Structural relaxation and rapid cooling were employed to examine the effect of free volume content on the deformation behavior. This was followed by detailed atomic structure analyses, employing the concepts of Voronoi polyhedra and "liquid-like" regions that contain high fraction of sub-atomic size open volumes. Results suggest that the total fraction of atoms in liquid-like regions is a key parameter that controls the plastic deformation in MGs. These are discussed in the context of reported experimental results and possible strategies for synthesizing monolithic amorphous materials that can accommodate large tensile plasticity are suggested.

  15. Closed Die Deformation Behavior of Cylindrical Iron-Alumina Metal Matrix Composites During Cold Sinter Forging

    Science.gov (United States)

    Prasanna Kumar, Undeti Jacob; Gupta, Pallav; Jha, Arun Kant; Kumar, Devendra

    2016-10-01

    The present paper aims to study the closed die deformation behavior of cylindrical Fe-Al2O3 metal matrix composites (MMCs). Closed die was manufactured by machining the high carbon steel block followed by oil quenching and then finishing. Samples sintered at a temperature of 1100 °C for 1 h were characterized with X-ray diffraction and scanning electron microscopy, which showed the formation of Fe, Al2O3 and nano size FeAl2O4 phases respectively. Density and hardness of the composite samples were determined after sintering. Closed die deformation studies of the prepared composite samples were carried under three different interfacial frictional conditions i.e. dry, solid lubricating and liquid lubricating. Hardness, density and metallographic characterizations were also done for the deformed samples. On comparing the micrographs of the samples before and after deformation it was revealed that in deformed specimens recrystallization has taken place due to the difference in the energy between the strained iron matrix and unstrained alumina reinforcement during closed die forging process. Experimental density of the samples was also verified with the theoretical density using the standard equations. It is expected that the results of the present investigations will be helpful in developing quality MMC components for wide industrial applications.

  16. Effect of Cu concentration on the semi-solid deformation behavior and microstructure of Ti–Cu alloy

    Directory of Open Access Journals (Sweden)

    Yong-Nan Chen

    2015-05-01

    Full Text Available The semi-solid compressive deformation behavior of Ti–Cu alloys was investigated by Gleeble-3500 hot simulator at the deformation temperatures ranging from 1273 to 1473 K with strain rates ranging from 5×10−3 to 5×10−1 s−1. The relationship between Cu concentration and flow stress was analyzed, and the deformation apparent activation energy was also calculated. The results show that Cu concentration has significant influence on the flows’ behavior of Ti–Cu alloys, especially at high semi-solid deformation temperatures. The Ti–14Cu exhibits the highest flow stress at 1273 and 1373 K, Ti–2.5Cu alloy exhibits the highest flow stress at 1473 K, and Ti–7Cu alloy shows the lowest flow stress at all tested temperatures, which corresponds to liquid fraction caused by varied Cu concentration and the deformation temperature. The difference in microstructure suggests that the shape and distribution of Ti2Cu precipitates are significantly affected by Cu concentration. The increase in Cu concentration leads to the growth and precipitation of acicular Ti2Cu along grain boundaries at high semi-solid deformation temperatures. The deformation apparent activation energy of Ti–14Cu alloy significantly decreases from solid deformation to semi-solid deformation owing to the change in main deformation mechanism from plastic deformation of solid particles to solid particles’ slippage and rotation of grain boundaries.

  17. Effect of Nb content on deformation behavior and shape memory properties of Ti–Nb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Tobe, H. [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Kim, H.Y., E-mail: heeykim@ims.tsukuba.ac.jp [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Inamura, T.; Hosoda, H. [Precision and Intelligence Laboratory, Tokyo Institute of Technology, Yokohama 226-8503 (Japan); Nam, T.H. [School of Materials Science and Engineering and ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Miyazaki, S., E-mail: miyazaki@ims.tsukuba.ac.jp [Division of Materials Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); School of Materials Science and Engineering and ERI, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Center of Excellence for Advanced Materials Research, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2013-11-15

    Highlights: ► Reorientation of martensite variants occurred by the deformation of the {1 1 1} type I and 〈2 1 1〉 type II twins. ► Magnitude of twinning shear in Ti–20Nb is larger than that in Ti–23Nb. ► Ti–20Nb exhibited a higher stress for the reorientation of martensite variants when compared with Ti–23Nb. -- Abstract: Deformation behavior and shape memory properties of Ti–(20, 23) at.% Nb alloys in a single α″ martensite state were investigated. The Ti–20Nb alloy exhibited a higher stress for the reorientation of martensite variants when compared with the Ti–23Nb alloy. The recovery strain due to the shape memory effect in the Ti–20Nb alloy was smaller than that in the Ti–23Nb alloy. Transmission electron microscope (TEM) observation revealed that the reorientation of martensite variants occurred by the deformation of {1 1 1} type I and 〈2 1 1〉 type II twins. The Nb content dependence of the deformation behavior and shape memory properties was discussed considering the magnitude of twinning shear of the twins.

  18. Effect of Deformation Mode on the Wear Behavior of NiTi Shape Memory Alloys

    Science.gov (United States)

    Yan, Lina; Liu, Yong

    2016-06-01

    Owing to good biocompatibility, good fatigue resistance, and excellent superelasticity, various types of bio-medical devices based on NiTi shape memory alloy (SMA) have been developed. Due to the complexity in deformation mode in service, for example NiTi implants, accurate assessment/prediction of the surface wear process is difficult. This study aims at providing a further insight into the effect of deformation mode on the wear behavior of NiTi SMA. In the present study, two types of wear testing modes were used, namely sliding wear mode and reciprocating wear mode, to investigate the effect of deformation mode on the wear behavior of NiTi SMA in both martensitic and austenitic states. It was found that, when in martensitic state and under high applied loads, sliding wear mode resulted in more surface damage as compared to that under reciprocating wear mode. When in austenitic state, although similar trends in the coefficient of friction were observed, the coefficient of friction and surface damage in general is less under reciprocating mode than under sliding mode. These observations were further discussed in terms of different deformation mechanisms involved in the wear tests, in particular, the reversibility of martensite variant reorientation and stress-induced phase transformation, respectively.

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

    Science.gov (United States)

    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.

  20. Hot Deformation Behavior of SiCP/A1-Cu Composite

    Directory of Open Access Journals (Sweden)

    CHENG Ming-yang

    2017-02-01

    Full Text Available Using the Gleeble-1500D simulator, the high temperature plastic deformation behavior of SiCp/Al-Cu composite were investigated at 350-500℃ with the strain rate of 0.01-10s-1. The true stress-strain curves were obtained in the tests. Constitutive equation and processing map were established. The results show that the softening mechanism of dynamic recrystallization is a feature of high-temperature flow stress-strain curves of SiCp/A1-Cu composite, and the peak stress increases with the decrease of deformation temperature or the increase of strain rate.The flow stress behavior of the composite during hot compression deformation can be represented by a Zener-Hollomon parameter in the hyperbolic sine form. Its activation energy for hot deformation Q is 320.79kJ/mol. The stable regions and the instability regions in the processing map were identified and the microstructures in different regions of processing map were studied.There are particle breakage and void in the instability regions.

  1. Low temperature deformation behavior of an electromagnetically bulged 5052 aluminum alloy

    Science.gov (United States)

    Li, Zu; Li, Ning; Wang, Duzhen; Ouyang, Di; Liu, Lin

    2016-07-01

    The fundamental understanding of the deformation behavior of electromagnetically formed metallic components under extreme conditions is important. Here, the effect of low temperature on the deformation behavior of an electromagnetically-bulged 5052 aluminum alloy was investigated through uniaxial tension. We found that the Portevin-Le Chatelier Effect, designated by the serrated characteristic in stress-strain curves, continuously decays until completely disappears with decreasing temperature. The physical origin of the phenomenon is rationalized on the basis of the theoretical analysis and the Monte Carlo simulation, which reveal an increasing resistance to dislocation motion imposed by lowering temperature. The dislocations are captured completely by solute atoms at ‑50 °C, which results in the extinction of Portevin-Le Chatelier. The detailed mechanism responsible for this process is further examined through Monte Carlo simulation.

  2. Deformation behavior of release agent coated glass fibre / epoxy composite using carbon nanotubes as strain sensors

    Directory of Open Access Journals (Sweden)

    Paweena Sureeyatanapas

    2013-02-01

    Full Text Available The deformation behavior of model glass fiber in epoxy composites has been studied using Raman spectroscopyproperties. Single walled carbon nanotubes (SWNTs were introduced at the glass fiber/epoxy interface as strain sensors,which can be detected by Raman Spectroscopy, to sense the strain profile of the fiber under deformation. The release agentwas applied on the fiber surface before composite fabrication. It was found that at high strain level, the behavior of a singlefiber in a composite did not follow a classical shear-lag model as shown in the fragmentation study. This is due to the interfacial failure caused by the release agent. The strain mapping result can be compared to that without release agent coating.The finding confirmed the application of SWNTs as strain sensors at the fiber/composite interface.

  3. Corrosion behavior of HPT-deformed TiNi alloys in cell culture medium

    Science.gov (United States)

    Shri, D. N. Awang; Tsuchiya, K.; Yamamoto, A.

    2017-09-01

    In recent years there are growing interest in fabrication of bulk nanostructured metals and alloys by using severe plastic deformation (SPD) techniques as new alternative in producing bulk nanocrystalline materials. These techniques allows for processing of bulk, fully dense workpiece with ultrafine grains. Metal undergoes SPD processing in certain techniques such as high pressure torsion (HPT), equal-channel angular pressing (ECAP) or multi-directional forging (MDF) are subjected to extensive hydrostatic pressure that may be used to impart a very high strain to the bulk solid without the introduction of any significant change in overall dimension of the sample. The change in the structure (small grain size and high-volume fraction of grain boundaries) of the material may result in the corrosion behavior different from that of the coarse-grained material. Electrochemical measurements were done to understand the corrosion behavior of TiNi alloys before and after HPT deformation. The experiment was carried out using standard three electrode setup (a sample as working electrode; a platinum wire as a counter electrode and a saturated calomel electrode in saturated KCl as a reference electrode) with the surface area of 26.42 mm2 exposed to the EMEM+10% FBS cell culture medium. The measurements were performed in an incubator with controlled environment at 37 °C and 5% CO2, simulating the cell culture condition. The potential of the specimen was monitored over 1 hour, and the stabilized potential was used as the open-circuit potential (EOCP). Potentiodynamic curves were scanned in the potential range from -0.5 V to 1.5 V relative to the EOCP, at a rate of 0.5 mV/s. The result of OCP-time measurement done in the cell culture medium shows that the OCP of HPT-deformed samples shifts towards to the more positive rather than that of BHPT samples. The OCP of deformed samples were ennobled to more than +70 mV for Ti-50mol%. The shift of OCP towards the nobler direction

  4. Specimen- and grain-size dependence of compression deformation behavior in nanocrystalline copper

    OpenAIRE

    Okamoto, Norihiko L.; Kashioka, Daisuke; Hirato, Tetsuji; Inui, Haruyuki

    2014-01-01

    The compression deformation behavior of electrodeposited nanocrystalline copper pillars with average grain sizes (d) of 360, 100, and 34 nm has been investigated as a function of specimen size (D). The yield stress for nanocrystalline pillars with d = 360 and 100 nm does not depend on specimen size, exhibiting essentially the bulk yield stress until the specimen size is reduced down to the critical values ((D/d)∗ = 35 and 85), below which the yield stress decreases with the decrease in specim...

  5. BASIC STUDY ON TENSION SOFTENING AND CYCLIC DEFORMATION BEHAVIOR OF SOLIDIFIED BODY FOR THE COHESIVE SOIL

    Science.gov (United States)

    Urano, Kazuhiko; Adachi, Yuji; Mihara, Masaya; Yamada, Atsuo; Kawamura, Makoto

    So far, authors have proposed a method to improve earthquake resistance of pile foundations by partially solidifying an underground part of the pile foundations, and the effect of reinforcement has been confirmed by shaking table tests and the lateral loading tests of a full scale model. Though the solidified body is usually designed as an elastic body, it is possible to design the body considering the damage by the tensile stress when a seismic ground motion is assumed to be level 2. Therefore, material tests of the solidified body for the cohesive soil were executed, and the characteristics of the tension softening and the cyclic deformation behavior of the solidified bod y were clarified. Moreover, loading tests that used wall models of the solidified body were executed, and the effects of the shape on the tension softening and the cyclic deformation behavior of the solidified body were clarified. In addition, a numerical simulation by elastoplastic FEM analysis that considers the damage of the solidified body was executed, and the tension softening and the cyclic deformation behavior of the solidified body were reproduced.

  6. Hot Deformation Behavior and Processing Maps of 2099 Al-Li Alloy

    Science.gov (United States)

    Chen, Bin; Tian, Xiao-lin; Li, Xiao-ling; Lu, Chen

    2014-06-01

    Hot deformation behavior and processing maps of the 2099 Al-Li alloy are investigated by tensile test at the temperature range from 250 to 450 °C and the strain rate range from 0.001 to 5.0 s-1. The typical true stress-true strain curves show that the flow stress increases with increasing the strain rate and decreasing the deforming temperature. All curves exhibit rapid work hardening at an initial stage of strain followed by remarkable dynamic softening. Based on the flow stress behavior, the processing maps are calculated and analyzed according to the dynamic materials model (DMM). The processing maps exhibit an instability domain in the temperature and strain rate ranges: T = 250-260 °C and = 0.1-0.5 s-1. The maps also exhibit an optimum hot working condition in the stability domain that occurs in the temperature of 400 °C for a strain rate of 0.001 s-1 and having a maximum efficiency of 60%. The microstructural examinations exhibit the occurrence of dynamic recovery (DRV) during hot deformation of the 2099 alloy which is the dominant softening mechanism in the alloy. The fracture behavior changes from a brittle fracture to a ductile fracture as strain rate decreases and temperature increases.

  7. Hot deformation behavior of an aluminum-matrix hybrid nanocomposite fabricated by friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Khodabakhshi, F. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of); Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON (Canada); Gerlich, A.P. [Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON (Canada); Simchi, A., E-mail: simchi@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of); Institute for Nanoscience and Nanotechnology, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of); Kokabi, A.H. [Department of Materials Science and Engineering, Sharif University of Technology, P.O. Box 11365-9466, Azadi Avenue, 14588 Tehran (Iran, Islamic Republic of)

    2015-02-25

    A fine-grained aluminum-matrix hybrid nanocomposite reinforced with TiO{sub 2}, MgO and Al{sub 3}Ti nanoparticles was prepared via reactive friction stir processing (FSP) of an Al–Mg sheet with pre-placed TiO{sub 2} particles (50 nm; 3.1 vol%). The microstructure of the hybrid nanocomposite comprises high-angle grain boundaries (~90%) with an average size of 2 µm and hard inclusions with sizes in the range of 30–50 nm. Evaluation of the hot deformation behavior of the nanocomposite by uniaxial tensile testing at different temperatures (300–450 °C) and strain rates (0.001–0.1 s{sup −1}) shows that the deformation apparent activation energy of the nanocomposite is 137 kJ mol{sup −1} at ≤300 °C. The values of the activation energy for the Al–Mg alloy before and after FSP at this temperature range are about 105 and 135 kJ mol{sup −1}, respectively. This observation highlights the role of ultrafine hard particles and the structural changes induced by FSP on the deformation process. At the higher temperatures, the deformation activation energy for the aluminum alloy without and with the reinforcing particles is 303 and 456 kJ mol{sup −1}, respectively. Detailed microstructural analysis by electron back scattered diffraction and transmission electron microscopy suggests that dynamic recrystallization is responsible for the deformation behavior at the elevated temperatures. Meanwhile, the presence of the hard nanoparticles operates as a grain growth inhibitor improving the thermal stability of the fine-grained aluminum alloy.

  8. Influence of adhesive shear deformation on laminate structural behavior with application to parabolic trough solar collectors

    Science.gov (United States)

    Clauss, D. B.; Reuter, R. C., Jr.

    1983-02-01

    A simplified theory for the bending behavior of a thin flat bilamina panel was developed which includes the effects of shear deformation in the central adhesive layer. Static equilibrium equations for elastic thermomechanical cylindrical bending of a thin plate are used. A solution form is proposed which greatly facilitates application of this theory to structural panels with numerous discrete property changes in the variable direction. The influence of adhesive shear stiffness parameters upon overall laminate behavior is characterized through numerical examples typifying various thermal and mechanical loading conditions.

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

    Science.gov (United States)

    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

  10. Deformation Behavior of Sub-micron and Micron Sized Alumina Particles in Compression.

    Energy Technology Data Exchange (ETDEWEB)

    Sarobol, Pylin; Chandross, Michael E.; Carroll, Jay; Mook, William; Boyce, Brad; Kotula, Paul Gabriel; McKenzie, Bonnie Beth; Bufford, Daniel Charles; Hall, Aaron Christopher.

    2014-09-01

    The ability to integrate ceramics with other materials has been limited due to high temperature (>800degC) ceramic processing. Recently, researchers demonstrated a novel process , aerosol deposition (AD), to fabricate ceramic films at room temperature (RT). In this process, sub - micro n sized ceramic particles are accelerated by pressurized gas, impacted on the substrate, plastically deformed, and form a dense film under vacuum. This AD process eliminates high temperature processing thereby enabling new coatings and device integration, in which ceramics can be deposited on metals, plastics, and glass. However, k nowledge in fundamental mechanisms for ceramic particle s to deform and form a dense ceramic film is still needed and is essential in advancing this novel RT technology. In this wo rk, a combination of experimentation and atomistic simulation was used to determine the deformation behavior of sub - micron sized ceramic particle s ; this is the first fundamental step needed to explain coating formation in the AD process . High purity, singl e crystal, alpha alumina particles with nominal size s of 0.3 um and 3.0 um were examined. Particle characterization, using transmission electron microscopy (TEM ), showed that the 0.3 u m particles were relatively defect - free single crystals whereas 3.0 u m p articles were highly defective single crystals or particles contained low angle grain boundaries. Sub - micron sized Al 2 O 3 particles exhibited ductile failure in compression. In situ compression experiments showed 0.3um particles deformed plastically, fractured, and became polycrystalline. Moreover, dislocation activit y was observed within the se particles during compression . These sub - micron sized Al 2 O 3 particles exhibited large accum ulated strain (2 - 3 times those of micron - sized particles) before first fracture. I n agreement with the findings from experimentation , a tomistic simulation s of nano - Al 2 O 3 particles showed dislocation slip and

  11. The relation between severe plastic deformation microstructure and corrosion behavior of AZ31 magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Ben Hamu, G. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Eliezer, D. [Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105 (Israel); Institute of Materials Science and Engineering, TU Clausthal (Germany)], E-mail: deliezer@bgu.ac.il; Wagner, L. [Institute of Materials Science and Engineering, TU Clausthal (Germany)

    2009-01-22

    The quest for ever, higher performance in structural applications has resulted in the outgoing development of new or improved materials with novel crystallographic textures, microstructures, and compositions. However, commercial applicability of such materials depends heavily on the development of economical and robust manufacturing methods. Due to the promise of excellent properties, such as superplasticity, high strength, good ductility, enhanced high cycle fatigue life, and good corrosion resistance, interest has grown in nanostructure bulk materials. Those materials are defined most often as materials exhibiting nanocrystalline grain structures and particle sizes below 100 nm in at least one dimension. In recent years, bulk nanostructure materials processed by methods of severe plastic deformation (SPD) such as equal channel angular extrusion (ECAE) have attracted the growing interest of specialists in materials science. The main object of this research is to compare the microstructural changing and corrosion behavior of magnesium alloy AZ31 after extrusion and severe plastic deformation by ECAE process. The ECAE process can produce intense and uniform deformation by simple shear and provides a convenient procedure for introducing an ultra fine grain size into a material. The samples were prepared by using hot extrusion methods. Hardness and AC and DC polarization tests were carried out on the extruded rods, and the microstructure was examined using optical, electron microscopy (SEM, TEM) and EDS. The results showed that the severe plastic deformation process affected both the microstructure and the corrosion behavior of AZ31 Mg alloy. These results can be explained by the effects of the process on microstructure of AZ31 Mg alloy such as grain size and dislocation density caused by the change in recrystallization behavior.

  12. Assessment of Tungsten Content on Tertiary Creep Deformation Behavior of Reduced Activation Ferritic-Martensitic Steel

    Science.gov (United States)

    Vanaja, J.; Laha, Kinkar

    2015-10-01

    Tertiary creep deformation behavior of reduced activation ferritic-martensitic (RAFM) steels having different tungsten contents has been assessed. Creep tests were carried out at 823 K (550 °C) over a stress range of 180 to 260 MPa on three heats of the RAFM steel (9Cr-W-0.06Ta-0.22V) with tungsten content of 1, 1.4, and 2.0 wt pct. With creep exposure, the steels exhibited minimum in creep rate followed by progressive increase in creep rate until fracture. The minimum creep rate decreased, rupture life increased, and the onset of tertiary stage of creep deformation delayed with the increase in tungsten content. The tertiary creep behavior has been assessed based on the relationship, , considering minimum creep rate () instead of steady-state creep rate. The increase in tungsten content was found to decrease the rate of acceleration of tertiary parameter ` p.' The relationships between (1) tertiary parameter `p' with minimum creep rate and time spent in tertiary creep deformation and (2) the final creep rate with minimum creep rate revealed that the same first-order reaction rate theory prevailed in the minimum creep rate as well as throughout the tertiary creep deformation behavior of the steel. A master tertiary creep curve of the steels has been developed. Scanning electron microscopic investigation revealed enhanced coarsening resistance of carbides in the steel on creep exposure with increase in tungsten content. The decrease in tertiary parameter ` p' with tungsten content with the consequent decrease in minimum creep rate and increase in rupture life has been attributed to the enhanced microstructural stability of the steel.

  13. Hot deformation and dynamic recrystallization behaviors of Mg–Gd–Y–Zr alloy

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, H.C. [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Jiang, S.N., E-mail: shnjiang@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); School of Civil Engineering, Central South University, Changsha 410083 (China); Tang, B.; Hao, W.H.; Gao, Y.H.; Chen, Z.Y.; Liu, C.M. [School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2015-03-25

    Hot deformation and dynamic recrystallization (DRX) behaviors of Mg–8.3Gd–2.6Y–0.4Zr alloy were investigated by uniaxial compression tests conducted at temperatures ranging from 300 °C to 500 °C and strain rates varying from 0.001 s{sup −1} to 1 s{sup −1}. The results reveal that the alloy exhibits a high deformability due to the DRX softening when the temperature is >400 °C. Apart from the premature failure at relative low temperatures, the stress–strain curves exhibit typical features of DRX that the flow stress presents a peak and then gradually declines to a steady-state. Optical microscopy examinations exhibit that DRX takes place dominantly either at twin boundaries or initial grain boundaries depending on the deformation conditions. With increasing temperature or decreasing strain rate, the DRX sites would transfer from the twin boundaries to initial grain boundaries gradually. The analysis of transmission electron microscopy (TEM) images indicates that the deformation is controlled by basal slip and twinning in the temperature range of 300–350 °C, continuous DRX associated with the operation of multiple slips plays a dominant role when temperature is >400 °C.

  14. Elastodynamic shape modeler: a tool for defining the deformation behavior of virtual tissues.

    Science.gov (United States)

    Radetzky, A; Nürnberger, A; Pretschner, D P

    2000-01-01

    A main goal of surgical simulators is the creation of virtual training environments for prospective surgeons. Thus, students can rehearse the various steps of surgical procedures on a computer system without any risk to the patient. One main condition for realistic training is the simulated interaction with virtual medical devices, such as endoscopic instruments. In particular, the virtual deformation and transection of tissues are important. For this application, a neuro-fuzzy model has been developed, which allows the description of the visual and haptic deformation behavior of the simulated tissue by means of expert knowledge in the form of medical terms. Pathologic conditions affecting the visual and haptic tissue response can be easily changed by a medical specialist without mathematical knowledge. By using the personal computer-based program Elastodynamic Shape Modeler, these conditions can be adjusted via a graphical user interface. With a force feedback device, which is similar to a real laparoscopic instrument, virtual deformations can be performed and the resulting haptic feedback can be felt. Thus, use of neuro-fuzzy technologies for the definition and calculation of virtual deformations seems applicable to the simulation of surgical interventions in virtual environments.

  15. High temperature deformation behavior and processing map for a nickel-titanium shape memory alloy

    Science.gov (United States)

    Yin, Xiang-Qian; Lee, Sang-Won; Li, Yan-Feng; Park, Chan-Hee; Mi, Xu-Jun; Yeom, Jong-Taek

    2017-09-01

    The hot deformation behavior of 49.2Ti-50.8Ni shape memory alloy was studied using hot compressive deformation testing in the temperature range of 1023-1323 K and at strain rates of 0.01-10 s-1. The work-hardening rate was induced to analyze the stress-strain curves, and the critical stress σc and the dynamic recovery saturation stress σsat were measured which can be specified approximately by the expressions: σsat-1.12σp and σc-0.86σp. An Arrhenius model was calculated to describe the relationship between peak stress and the Z parameter. The relationship between deformation activation energy, the deformation conditions and the effect of Ni component in a binary TiNi alloy on the activation energy were discussed in this work. With the help of electron backscattering diffraction, a connected mode dynamic recrystallization microstructure was confirmed in peak efficiency regimes (850 °C & 0.01 s-1 and 1050 °C & 10 s-1) of the processing map.

  16. Effects of Initial Microstructure Characteristics on Hot Deformation Behaviors of 2E12 Aluminum Alloy

    Directory of Open Access Journals (Sweden)

    PAN Su-ping

    2016-11-01

    Full Text Available Three alloys with different microstructure characteristics were prepared, which microstructures were characterized as enriched with eutectics, supersaturated solid solution and coarse precipitates. Combined isothermal hot compression test and microstructure observation, the hot deformation behaviors of three alloys were studied in the temperature range of 340-490℃ and strain rate range of 0.001-10s-1. The results show initial microstructure characteristics have significant influences on the hot deformation of alloys. Among three alloys, the alloy enriched with coarse precipitates has the largest peak stress value while the alloy enriched with eutectics has the smallest one. The flow behaviors of three alloys were described by the hyperbolic sine constitutive equations. The deformation activation energy for three alloys calculated to be 178.6, 222.1, 154.9kJ/mol, respectively. The processing maps were calculated and analyzed according to the dynamic materials model. Among three alloys, the alloy enriched with coarse precipitates has the widest processing range while the alloy enriched with eutectics has the narrowest one.

  17. Hot-Deformation Behavior and Hot-Processing Maps of AISI 410 Martensitic Stainless Steel

    Science.gov (United States)

    Qi, Rong-Sheng; Jin, Miao; Guo, Bao-Feng; Liu, Xin-Gang; Chen, Lei

    2016-10-01

    The compressive deformation behaviors of 410 martensitic stainless steel were investigated on a Gleeble-1500 thermomechanical simulator, and the experimental stress-strain data were obtained. The measured flow stress was corrected for friction and temperature. A constitutive equation that accounts for the influence of strain was established, and the hot-processing maps at different strain were plotted. The microstructure evolution of the hot-deformation process was studied on the basis of microstructural observations at high temperatures. Phase-transformation experiments on 410 steel were conducted at high temperatures to elucidate the effects of temperature on the delta-ferrite content. The initial forging temperature and optimum process parameters were obtained on the basis of the processing map and the changes in the delta-ferrite content at high temperatures.

  18. Modelling the viscoplastic behavior and the heterogeneous intracrystalline deformation of columnar ice polycrystals

    Energy Technology Data Exchange (ETDEWEB)

    Lebensohn, Ricardo A [Los Alamos National Laboratory; Montagnat, Maurine [LGGE (FRANCE); Mansuy, Philippe [MICHELIN (FRANCE); Duval, Paul [LGGE (FRANCE); Philip, A [LGGE (FRANCE)

    2008-01-01

    A full-field formulation based on Fast Fourier Transforms (FFT) has been adapted and used to predict the micromechanical fields that develop in columnar Ih ice polycrystals deforming in compression by dislocation creep. The predicted intragranular mechanical fields are in qualitative good agreement with experimental observations, in particular those involving the formation of shear and kink bands. These localization bands are associated with the large internal stresses that develop during creep in such anisotropic material, and their location, intensity, morphology and extension are found to depend strongly on the crystallographic orientation of the grains and on their interaction with neighbor crystals. The predictions of the model are also discussed in relation with the deformation of columnar sea and lake ice, and with the mechanical behavior of granular ice of glaciers and polar ice sheets, as well.

  19. Quasi-static Torsional Deformation Behavior of Porous Ti6Al4V alloy.

    Science.gov (United States)

    Balla, Vamsi Krishna; Martinez, Shantel; Rogoza, Ben Tunberg; Livingston, Chase; Venkateswaran, Deepak; Bose, Susmita; Bandyopadhyay, Amit

    2011-07-20

    Laser processed Ti6Al4V alloy samples with total porosities of 0%, 10% and 20% have been subjected to torsional loading to determine mechanical properties and to understand the deformation behavior. The torsional yield strength and modulus of porous Ti alloy samples was found to be in the range of 185-332 MPa and 5.7-11 GPa, respectively. With an increase in the porosity both the strength and the modulus decreased, and at 20% porosity the torsional modulus of Ti6Al4V alloy was found to be very close to that of human cortical bone. Further, the experiments revealed clear strain hardening and ductile deformation in all the samples, which suggests that the inherent brittleness associated solid-state sintered porous materials can be completely eliminated via laser processing for load bearing metal implant applications.

  20. Hot Deformation Behavior of SA508Gr.4N Steel for Reactor Pressure Vessels

    Directory of Open Access Journals (Sweden)

    YANG Zhi-qiang

    2017-08-01

    Full Text Available The high-temperature plastic deformation and dynamic recrystallization behavior of SA508Gr.4N steel were investigated through hot deformation tests in a Gleeble1500D thermal mechanical simulator. The compression tests were performed in the temperature range of 1050-1250℃ and the strain rate range of 0.001-0.1s-1 with true strain of 0.16. The results show that from the high-temperature true stress-strain curves of the SA508Gr.4N steel, the main feature is dynamic recrystallization,and the peak stress increases with the decrease of deformation temperature or the increase of strain rate, indicating the experimental steel is temperature and strain rate sensitive material. The constitutive equation for SA508Gr.4N steel is established on the basis of the true stress-strain curves, and exhibits the characteristics of the high-temperature flow behavior quite well, while the activation energy of the steel is determined to be 383.862kJ/mol. Furthermore, an inflection point is found in the θ-σ curve, while the -dθ/dσ-σ curve shows a minimum value. The critical strain increases with increasing strain rate and decreasing deformation temperature. A linear relationship between critical strain (εc and peak strain (εp is found and could be expressed as εc/εp=0.517. The predicted model of critical strain could be described as εc=8.57×10-4Z0.148.

  1. Macroscopic quantum resonators (MAQRO)

    CERN Document Server

    Kaltenbaek, Rainer; Kiesel, Nikolai; Romero-Isart, Oriol; Johann, Ulrich; Aspelmeyer, Markus

    2012-01-01

    Quantum physics challenges our understanding of the nature of physical reality and of space-time and suggests the necessity of radical revisions of their underlying concepts. Experimental tests of quantum phenomena involving massive macroscopic objects would provide novel insights into these fundamental questions. Making use of the unique environment provided by space, MAQRO aims at investigating this largely unexplored realm of macroscopic quantum physics. MAQRO has originally been proposed as a medium-sized fundamental-science space mission for the 2010 call of Cosmic Vision. MAQRO unites two experiments: DECIDE (DECoherence In Double-Slit Experiments) and CASE (Comparative Acceleration Sensing Experiment). The main scientific objective of MAQRO, which is addressed by the experiment DECIDE, is to test the predictions of quantum theory for quantum superpositions of macroscopic objects containing more than 10e8 atoms. Under these conditions, deviations due to various suggested alternative models to quantum th...

  2. Modeling of stress relaxation of a semi-crystalline multiblock copolymer and its deformation behavior.

    Science.gov (United States)

    Yan, Wan; Fang, Liang; Heuchel, Matthias; Kratz, Karl; Lendlein, Andreas

    2015-01-01

    Stress relaxation can strongly influence the shape-memory capability of polymers. Recently a modified Maxwell-Wiechert model comprising two Maxwell units and a single spring unit in parallel has been introduced to successfully describe the shape recovery characteristics of amorphous polyether urethanes. In this work we explored whether such a modified Maxwell-Wiechert model is capable to describe the stress relaxation behavior of a semi-crystalline multiblock copolymer named PCL-PIBMD, which consists of crystallizable poly(ɛ-caprolactone) (PCL) segments and crystallizable poly(3S-isobutylmorpholine-2,5-dione) (PIBMD) segments. The stress relaxation behavior of PCL-PIBMD was explored after uniaxial deformation to different strains ranging from 50 to 900% with various strain rates of 1 or 10 or 50 mm·min -1. The modeling results indicated that under the assumption that in PCL-PIBMD both PCL and PIBMD blocks have narrow molecular weight distributions and are arranged in sequence, the two relaxation processes can be related to the amorphous PCL and PIBMD domains and the spring element can be associated to the PIBMD crystalline domains. The first Maxwell unit representing the faster relaxation process characterized by the modulus E1 and the relaxation time τ1 is related to the amorphous PCL domains (which are in the rubbery state), while the second Maxwell unit (E2 ; τ2) represents the behavior of the amorphous PIBMD domains, which are in the glassy state at 50 °C. Increasing strain rates resulted in an increase of E1 and a significant reduction in τ1, whereas the elastic modulus as well as the relaxation time related to the amorphous PIBMD domains remained almost constant. When a higher deformation was applied (ɛ ≥ 200% ) lower values for the elastic moduli of the three model elements were obtained. In general the applied model was also capable to describe the relaxation behavior of PCL-PIBMD at a deformation temperature of 20 °C, where additional crystalline

  3. Time-dependent deformation behavior of polyvinylidene fluoride binder: Implications on the mechanics of composite electrodes

    Science.gov (United States)

    Santimetaneedol, Arnuparp; Tripuraneni, Rajasekhar; Chester, Shawn A.; Nadimpalli, Siva P. V.

    2016-11-01

    The majority of existing battery models that simulate composite electrode behavior assume the binder as a linear elastic material due to lack of a thorough understanding of time-dependent mechanical behavior of binders. Here, thin films of polyvinylidene fluoride binder, prepared according to commercial battery manufacturing method, are subjected to standard monotonic, load-unload, and relaxation tests to characterize the time-dependent mechanical behavior. The strain in the binder samples is measured with the digital image correlation technique to eliminate experimental errors. The experimental data showed that for (charging/discharging) time scales of practical importance, polyvinylidene fluoride behaves more like an elastic-viscoplastic material as opposed to a visco-elastic material; based on this observation, a simple elastic-viscoplastic model, calibrated against the data is adopted to represent the deformation behavior of binder in a Si-based composite electrode; the lithiation/delithiation process of this composite was simulated at different C rates and the stress/strain behavior was monitored. It is observed that the linear elastic assumption of the binder leads to inaccurate results and the time-dependent constitutive behavior of the binder not only leads to accurate prediction of the mechanics but is an essential step towards developing advanced multi-physics models for simulating the degradation behavior of batteries.

  4. Understanding compressive deformation behavior of porous Ti using finite element analysis

    Energy Technology Data Exchange (ETDEWEB)

    Roy, Sandipan; Khutia, Niloy [Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur (India); Das, Debdulal [Department of Metallurgy and Materials Engineering, Indian Institute of Engineering Science and Technology, Shibpur (India); Das, Mitun, E-mail: mitun@cgcri.res.in [Bioceramics and Coating Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata (India); Balla, Vamsi Krishna [Bioceramics and Coating Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata (India); Bandyopadhyay, Amit [W. M. Keck Biomedical Materials Research Laboratory, School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Chowdhury, Amit Roy, E-mail: arcbesu@gmail.com [Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur (India)

    2016-07-01

    In the present study, porous commercially pure (CP) Ti samples with different volume fraction of porosities were fabricated using a commercial additive manufacturing technique namely laser engineered net shaping (LENS™). Mechanical behavior of solid and porous samples was evaluated at room temperature under quasi-static compressive loading. Fracture surfaces of the failed samples were analyzed to determine the failure modes. Finite Element (FE) analysis using representative volume element (RVE) model and micro-computed tomography (CT) based model have been performed to understand the deformation behavior of laser deposited solid and porous CP-Ti samples. In vitro cell culture on laser processed porous CP-Ti surfaces showed normal cell proliferation with time, and confirmed non-toxic nature of these samples. - Highlights: • Porous CP-Ti samples fabricated using additive manufacturing technique • Compressive deformation behavior of porous samples closely matches with micro-CT and RVE based analysis • In vitro studies showed better cell proliferation with time on porous CP-Ti surfaces.

  5. Deformation Behavior and TExture Evolution of Steel Alloys under Axial-Torsional Loading

    Energy Technology Data Exchange (ETDEWEB)

    Siriruk, A.; Kant, M.; Penumadu, D.; Garlea, E.; Vogel, S.

    2011-06-01

    Using hollow cylinder samples with suitable geometry obtained from round bar stock, the deformation behavior of bcc Fe based 12L14 steel alloy is evaluated under multi-axial conditions. A stacked strain gage rosette and extensometer mounted on the cylindrical surface at the mid height of the specimen provided strain tensor as a function of applied stress for pure tensile and torsion tests prior to yielding. This study examines elastic and yield behavior and effects of these with respect to texture evolution. Hollow cylinder specimen geometry (tubes) with small wall thickness and relatively (to its thickness) large inner diameter is used. The variation of observed yield surface in deviatoric plane and the effect on mode of deformation (tension versus torsion versus its combination) on stress-strain behavior is discussed. Bulk texture was studied using neutron time-of-flight diffractometer at High-Pressure-Preferred Orientation (HIPPO) - Los Alamos Neutron Science Center (LANSCE) instrument and the evolution of texture and related anisotropy for pure tension versus torsion are also included.

  6. An Explicit Approach Toward Modeling Thermo-Coupled Deformation Behaviors of SMPs

    Directory of Open Access Journals (Sweden)

    Hao Li

    2017-03-01

    Full Text Available A new elastoplastic J 2 -flow models with thermal effects is proposed toward simulating thermo-coupled finite deformation behaviors of shape memory polymers. In this new model, an elastic potential evolving with development of plastic flow is incorporated to characterize the stress-softening effect at unloading and, moreover, thermo-induced plastic flow is introduced to represent the strain recovery effect at heating. It is shown that any given test data for both effects may be accurately simulated by means of direct and explicit procedures. Numerical examples for model predictions compare well with test data in literature.

  7. Precipitation behavior in a nitride-strengthened martensitic heat resistant steel during hot deformation

    Directory of Open Access Journals (Sweden)

    Wenfeng Zhang

    2015-09-01

    Full Text Available The stress relaxation curves for three different hot deformation processes in the temperature range of 750–1000 °C were studied to develop an understanding of the precipitation behavior in a nitride-strengthened martensitic heat resistant steel (Zhang et al., Mater. Sci. Eng. A, 2015 [1]. This data article provides supporting data and detailed information on how to accurately analysis the stress relaxation data. The statistical analysis of the stress peak curves, including the number of peaks, the intensity of the peaks and the integral value of the pumps, was carried out. Meanwhile, the XRD energy spectrum data was also calculated in terms of lattice distortion.

  8. A molecular mechanics approach for analyzing tensile nonlinear deformation behavior of single-walled carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    Yu Wang; Daining Fang; Ai Kah Soh; Bin Liu

    2007-01-01

    In this paper, by capturing the atomic informa-tion and reflecting the behaviour governed by the nonlin-ear potential function, an analytical molecular mechanics approach is proposed. A constitutive relation for single-walled carbon nanotubes (SWCNT's) is established to describe the nonlinear stress-strain curve of SWCNT's and to predict both the elastic properties and breaking strain of SWCNT's during tensile deformation. An analysis based on the virtual internal bond (VIB) model proposed by P. Zhang et al. is also presented for comparison. The results indicate that the proposed molecular mechanics approach is indeed an acceptable analytical method for analyzing the mechanical behavior of SWCNT's.

  9. Laser deposition and deformation behavior of Ti-Nb-Zr-Ta alloys for orthopedic implants.

    Science.gov (United States)

    Nag, S; Banerjee, R

    2012-12-01

    Microstructure and mechanical properties of laser deposited complex quaternary Ti-34Nb-7Zr-7Ta (all wt%), an orthopedic load-bearing implant alloy, has been investigated in detail in both as-deposited as well as heat-treated (β-solutionized and quenched) conditions. The difference in stress-strain behavior of this alloy in the above conditions has been characterized using scanning electron microscopy (SEM), orientation imaging microscopy (OIM™) and transmission electron microscopy (TEM). Compared to the sample in heat-treated condition, the as-deposited sample showed evidence of strong growth related texture. Again in the as-deposited post tensile-tested condition formation of a high density of shear bands, possibly arising from slip localization due to shearing of ω precipitates in the β matrix is observed. TEM investigations also show the presence of lenticular shaped deformation induced ω phase within the shear bands. In contrast, in case of the β-solutionized sample, twinning and the formation of stress-induced plates appears to be the primary mode of deformation. The change in deformation mechanism and thus the tensile property of this alloy could be attributed to the crystallographic texture along the growth direction as well as diffusion mediated isothermal ω precipitates, that cause an enrichment of Nb and Ta in the β matrix, during the laser-deposition process. This is no longer present after the solutionizing treatment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Bonding Behavior of Deformed Steel Rebars in Sustainable Concrete Containing both Fine and Coarse Recycled Aggregates.

    Science.gov (United States)

    Kim, Sun-Woo; Park, Wan-Shin; Jang, Young-Il; Jang, Seok-Joon; Yun, Hyun-Do

    2017-09-14

    In order to assess the bond behavior of deformed steel rebars in recycled-aggregate concrete (RAC) incorporating both fine and coarse recycled aggregate, pull-out tests were carried out in this study on 16-mm diameter deformed steel rebars embedded concentrically in RAC. The concrete was designed using equivalently mixed proportions of both recycled coarse aggregate and recycled fine aggregate. The tests employed five types of recycled aggregate replacement combinations and three types of rebar placement orientation (i.e., vertical bars and two-tiered and three-tiered horizontal bars). Based on the pull-out test results, the maximum bond strength tended to decrease and the slip at the maximum bond strength increased as the average water absorption of the aggregate increased, irrespective of the rebar orientation or placement location within the concrete member. The pull-out test results for the horizontal steel rebars embedded in RAC indicate that the casting position effect could be determined from the mid-depth of the concrete member, irrespective of the member's height. The normalized bond versus slip relationship between the deformed rebar and the RAC could be predicted using an empirical model based on regression analysis of the experimental data.

  11. Hot Deformation Behavior of 1Cr12Ni3Mo2VN Martensitic Stainless Steel

    Science.gov (United States)

    He, Xiaomao; Jiang, Peng; Zhou, Leyu; Chen, Chao; Deng, Xiaochun

    2017-08-01

    1Cr12Ni3Mo2VN is a new type of martensitic stainless steel for the last-stage blades of large-capacity nuclear and thermal power turbines. The deformation behavior of this steel was studied by thermal compression experiments that performed on a Gleeble-3500 thermal simulator at a temperature range of 850°C to 1200°C and a strain rate of 0.01s-1 to 20s-1. When the deformation was performed at high temperature and low strain rate, a necklace type of microstructures was observed, the plastic deformation mechanism is grain boundary slip and migration, when at low temperature and lower strain rate, the slip bands were observed, the mechanism is intracrystalline slips, and when at strain rate of 20s-1, twins were observed, the mechanism are slips and twins. The Arrhenius equation was applied to describe the constitutive equation of the flow stress. The accuracy of the equation was verified by using the experimental data and the correlation coefficient R2 = 0.9786, and the equation can provide reasonable data for the design and numerical simulation of the forging process.

  12. The deformation behavior of solid polymers and modeling with the viscoplasticity theory based on overstress

    Science.gov (United States)

    Khan, Fazeel Jilani

    The inelastic deformation of six engineering polymers has been investigated with the desideratum being a thorough mapping of the mechanical response characteristics and the subsequent application of a state-variable based constitutive material model to the data. Materials included in the investigation were polycarbonate (PC), Nylon 66, high-density polyethylene (HDPE), polyethylene-terephthalate (PET), polyethersulfone (PES) and polyphenylene oxide (PPO). Cylindrical specimens were machined from as-received rod stock. The use of a servo-hydraulic test frame with control mode switching capability has permitted data collection under strain and load controlled test configurations. In the region of homogeneous deformation with strain typically less than 10%, during loading all materials have been found to exhibit, (i) positive non-linear rate sensitivity in loading, (ii) the magnitude of the response in creep, relaxation and recovery tests varies non-linearly with changes in the prior loading rate, and (iii) in the inelastic flow region the stress drop in relaxation has been found to be independent of the test strain value. In addition to these findings, perhaps the most singular deformation response has been in the instance of relaxation (creep) during unloading when the rate of change of stress (strain) may undergo a change in sign. This phenomenon has been labeled 'rate reversal' and has surfaced in tensile and compression load conditions. The preponderance of data, therefore, suggests that the amorphous versus crystalline distinction does not largely manifest itself in the qualitative nature of the deformation behavior. This finding endorses the competence of macro-based models to undertake the task of polymer deformation modeling. Common response characteristics such as positive strain rate sensitivity, monotonic decreases in the stress magnitude in a relaxation test (strain hold), and response during creep have been modeled well with the existing viscoplasticity

  13. Hot Ductility and Compression Deformation Behavior of TRIP980 at Elevated Temperatures

    Science.gov (United States)

    Zhang, Mei; Li, Haiyang; Gan, Bin; Zhao, Xue; Yao, Yi; Wang, Li

    2017-04-01

    The hot ductility tests of a kind of 980 MPa class Fe-0.31C (wt pct) TRIP steel (TRIP980) with the addition of Ti/V/Nb were conducted on a Gleeble-3500 thermomechanical simulator in the temperatures ranging from 873 K to 1573 K (600 °C to 1300 °C) at a constant strain rate of 0.001 s-1. It is found that the hot ductility trough ranges from 873 K to 1123 K (600 °C to 850 °C). The recommended straightening temperatures are from 1173 K to 1523 K (900 °C to 1250 °C). The isothermal hot compression deformation behavior was also studied by means of Gleeble-3500 in the temperatures ranging from 1173 K to 1373 K (900 °C to 1100 °C) at strain rates ranging from 0.01 s-1 to 10 s-1. The results show that the peak stress decreases with the increasing temperature and the decreasing strain rate. The deformation activation energy of the test steel is 436.7 kJ/mol. The hot deformation equation of the steel has been established, and the processing maps have been developed on the basis of experimental data and the principle of dynamic materials model (DMM). By analyzing the processing maps of strains of 0.5, 0.7, and 0.9, it is found that dynamic recrystallization occurs in the peak power dissipation efficiency domain, which is the optimal area of hot working. Finally, the factors influencing hot ductility and thermal activation energy of the test steel were investigated by means of microscopic analysis. It indicates that the additional microalloying elements play important roles both in the loss of hot ductility and in the enormous increase of deformation activation energy for the TRIP980 steel.

  14. Ghost spins and quantum critical behavior in a spin chain with local bond deformation

    Science.gov (United States)

    Dai, Jianhui; Wang, Yupeng; Eckern, U.

    1999-09-01

    We study the impurity-induced critical behavior in an integrable SU(2)-invariant model consisting of an open spin chain of arbitrary spin S (Takhatajian-Babujian model) interacting with an impurity of spin S-->' located at one of the boundaries. For S=1/2 or S'=1/2, the impurity interaction takes a very simple form JS-->1.S-->' that describes the deformed boundary bond between the impurity S-->' and the first bulk spin S-->1 with an arbitrary coupling strength J. For a weak coupling 0S, and S'=J0/[(S+S')2-1/4], the impurity spin is split into two ghost spins. Their cooperative effect leads to a variety of new critical behaviors with different values of \\|S'-S\\|.

  15. Hot deformation behavior of a spray-deposited AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    LI Yongbing; CHEN Yunbo; CUI Hua; DING Jie; ZUO Lingli; ZHANG Jishan

    2009-01-01

    The flow stress behavior of an as-spray-deposited AZ31 magnesium alloy with fine grains was investigated by means of compression tests with a Gleeble 1500 thermal mechanical simulator at isothermal constant strain rates of 0.01, 0.1, 1.0, and 10 s-1; the testing temperatures ranged from 623 to 723 K. It is demonstrated that a linear equation can be fitted between the Zemer-Hollomon parameter Z and stress in a double-log scale. The effect of deformation parameters on the behavior of recrystallization was analyzed. Dynamic recrystallization (DRX) generally occurs at a higher temperature and at a lower strain rate. The constitutive equation of the spray-deposited AZ31 magnesium alloy is elevated temperatures due to the fine grain, which provides a large amount of nucleation sites and a high-diffnsivity path for the atom.

  16. Effective-stress-law behavior of Austin chalk rocks for deformation and fracture conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Warpinski, N.R.; Teufel, L.W.

    1994-08-01

    Austin chalk core has been tested to determine the effective law for deformation of the matrix material and the stress-sensitive conductivity of the natural fractures. For deformation behavior, two samples provided data on the variations of the poroelastic parameter, {alpha}, for Austin chalk, giving values around 0.4. The effective-stress-law behavior of a Saratoga limestone sample was also measured for the purpose of obtaining a comparison with a somewhat more porous carbonate rock. {alpha} for this rock was found to be near 0.9. The low {alpha} for the Austin chalk suggests that stresses in the reservoir, or around the wellbore, will not change much with changes in pore pressure, as the contribution of the fluid pressure is small. Three natural fractures from the Austin chalk were tested, but two of the fractures were very tight and probably do not contribute much to production. The third sample was highly conductive and showed some stress sensitivity with a factor of three reduction in conductivity over a net stress increase of 3000 psi. Natural fractures also showed a propensity for permanent damage when net stressed exceeded about 3000 psi. This damage was irreversible and significantly affected conductivity. {alpha} was difficult to determine and most tests were inconclusive, although the results from one sample suggested that {alpha} was near unity.

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

    Energy Technology Data Exchange (ETDEWEB)

    Krempl, E. [Rensselaer Polytechnic Institute, Troy, NY (United States)

    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.

  18. Evaluation of Dynamic Deformation Behaviors in Metallic Materials under High Strain-Rates Using Taylor Bar Impact Test

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Kyung Oh; Shin, Hyung Seop [Andong National Univ., Andong (Korea, Republic of)

    2016-09-15

    To ensure the reliability and safety of various mechanical systems in accordance with their high-speed usage, it is necessary to evaluate the dynamic deformation behavior of structural materials under impact load. However, it is not easy to understand the dynamic deformation behavior of the structural materials using experimental methods in the high strain-rate range exceeding 10{sup 4} s{sup -1}. In this study, the Taylor bar impact test was conducted to investigate the dynamic deformation behavior of metallic materials in the high strain-rate region, using a high-speed photography system. Numerical analysis of the Taylor bar impact test was performed using AUTODYN S/W. The results of the analysis were compared with the experimental results, and the material behavior in the high strain-rate region was discussed.

  19. Deformation behavior of metastable β-type Ti-25Nb-2Mo-4Sn alloy for biomedical applications.

    Science.gov (United States)

    Guo, S; Meng, Q K; Cheng, X N; Zhao, X Q

    2014-10-01

    The deformation behavior of metastable β-type Ti-25Nb-2Mo-4Sn (wt%) alloy subjected to different thermo-mechanical treatments was discussed by the combining results from transmission electron microscope, tensile test and in-situ synchrotron X-ray diffraction. Visible "double yielding" behavior, which is characterized by the presence of stress-plateau, was observed in the solution treated specimen. Upon a cold rolling treatment, the Ti-25Nb-2Mo-4Sn alloy performs nonlinear deformation because of the combined effects of elastic deformation and stress-induced α″ martensitic transformation. After the subsequent annealing, the β phase is completely stabilized and no stress-induced martensitic transformation takes place on loading due to the inhibitory effect of grain boundaries and dislocations on martensitic transformation. As a result, the annealed specimen exhibits linear elastic deformation.

  20. Microscale Mechanical Deformation Behaviors and Mechanisms in Bulk Metallic Glasses Investigated with Micropillar Compression Experiments

    Science.gov (United States)

    Ye, Jianchao

    2011-12-01

    Over the past years of my PhD study, the focused-ion-beam (FIB) based microcompression experiment has been thoroughly investigated with respect to the small-scale deformation in metallic glasses. It was then utilized to explore the elastic and plastic deformation mechanisms in metallic glasses. To this end, micropillars with varying sample sizes and aspect ratios were fabricated by the FIB technique and subsequently compressed on a modified nanoindentation system. An improved formula for the measurement of the Young's modulus was derived by adding a geometrical prefactor to the Sneddon's solution. Through the formula, geometry-independent Young's moduli were extracted from microcompression experiments, which are consistent with nanoindentation results. Furthermore, cyclic microcompression was developed, which revealed reversible inelastic deformation in the apparent elastic regime through high-frequency cyclic loading. The reversible inelastic deformation manifests as hysteric loops in cyclic microcompression and can be captured by the Kelvin-type viscoelastic model. The experimental results indicate that the free-volume zones behave essentially like supercooled liquids with an effective viscosity on the order of 1 x 108 Pas. The microscopic yield strengths were first extracted with a formula derived based on the Mohr-Coulomb law to account for the geometrical effects from the tapered micropillar and the results showed a weak size effect on the yield strengths of a variety of metallic-glass alloys, which can be attributed to Weibull statistics. The nature of the yielding phenomenon was explored with the cyclic micro-compression approach. Through cyclic microcompression of a Zr-based metallic glass, it can be demonstrated that its yielding stress increases at higher applied stress rate but its yielding strain is kept at a constant of ~ 2%. The room-temperature post-yielding deformation behavior of metallic glasses is characterized by flow serrations, which were

  1. A Computational Investigation on Bending Deformation Behavior at Various Deflection Rates for Enhancement of Absorbable Energy in TRIP Steel

    Science.gov (United States)

    Pham, Hang Thi; Iwamoto, Takeshi

    2016-08-01

    Transformation-induced plasticity (TRIP) steel might have a high energy-absorption characteristic because it could possibly consume impact energy by not only plastic deformation but also strain-induced martensitic transformation (SIMT) during deformation. Therefore, TRIP steel is considered to be suitable for automotive structures from the viewpoint of safety. Bending deformation due to buckling is one of the major collapse modes of automotive structures. Thus, an investigation on the bending deformation behavior and energy-absorption characteristic in TRIP steel at high deformation rate is indispensable to clarify the mechanism of better performance. Some past studies have focused on the improvement of mechanical properties by means of SIMT; however, the mechanism through which the energy-absorption characteristic in steel can be improved is still unclear. In this study, the three-point bending deformation behavior of a beam specimen made of type-304 austenitic stainless steel, a kind of TRIP steel, is investigated at various deflection rates by experiments and finite-element simulations based on a constitutive model proposed by one of the authors. After confirming the validity of the computation, the rate-sensitivity of energy absorption from the viewpoint of hardening behavior is examined and the improvement of the energy-absorption characteristic in TRIP steel including its mechanism is discussed.

  2. A Composite Modeling Analysis of the Deformation Behavior of Medium Manganese Steels

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Radhakanta [CSM/ASPPRC; Gibbs, Paul J [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); De Moor, Emmanuel [CSM/ASPPRC; Speer, John G [CSM/ASPPRC; Matlock, David K [CSM/ASPPRC

    2014-09-01

    The deformation behavior of medium manganese steels was evaluated with uniaxial tensile testing and the results were correlated with predictions of a composite model shown previously to provide design insight into the development of multi-phase steels with third-generation advanced high strength steel (3GAHSS) properties. An equilibrium thermodynamic-based methodology to design microstructures containing systematic amounts of metastable austenite with controlled stability against transformation is presented. The analysis is based on Mn enrichment of austenite during intercritical annealing of medium Mn (7 and 10 wt pct.) low carbon (0.1 and 0.15 wt pct) steels. The steels were produced as laboratory heats that were hot and cold rolled prior to annealing. After annealing the microstructures consisted primarily of either a matrix of fine grained ferrite with austenite contents between 32.6 and 45.2 wt pct (7Mn, 0.1C steels) or a matrix of martensite with various amounts of austenite in the higher Mn steel. The different intercritical annealing conditions produced steels with wide variations in austenite contents and austenite compositions (Mn and C contents) resulting in steels with significant variations in austenite stability. Predictions based on the composite analysis with different assumed flow behaviors for the individual constituents and stability functions for the meta-stable austenite are presented and shown to accurately predict strength-ductility combinations over a range of austenite volume fractions for the 7Mn steel. Applicability of the composite analysis is extended to consider the deformation behavior of the 10Mn steel and evaluate other possible microstructural combinations leading to 3GAHSS properties.

  3. Deformation behavior and microstructural evolution of 7075-T6 aluminum alloy at cryogenic temperatures

    Science.gov (United States)

    Lee, Woei-Shyan; Lin, Ching-Rong

    2016-10-01

    The impact deformation behavior and associated microstructural evolution of 7075-T6 aluminum alloy at cryogenic temperatures are investigated using a compressive split-Hopkinson pressure bar (SHPB) system. Cylindrical specimens are deformed at strain rates of 1 × 103 s-1, 2 × 103 s-1, 3 × 103 s-1 and 5 × 103 s-1 and temperatures of 0 °C, -100 °C and -196 °C. It is shown that the flow stress is strongly dependent on the strain rate and temperature. For a given temperature, the flow stress varies with the strain rate in accordance with a power law relation with an average exponent of 0.157 and an activation energy of 0.7 kJ/mol. Moreover, the coupled effects of the strain rate and temperature on the flow stress are adequately described by the Zener-Hollomon parameter (Z). For all test temperatures, catastrophic failure occurs only under the highest strain rate of 5 × 103 s-1, and is the result of adiabatic shear. An increasing strain rate or reducing temperature leads to a greater dislocation density and a smaller grain size. Finally, the dependence of the flow stress on the microstructural properties of the impacted 7075-T6 specimens is well described by a specific Hall-Petch constitutive model with constants of K = 108.3 MPa μm1/2 and K‧ = 16.1 MPa μm, respectively. Overall, the results presented in this study provide a useful insight into the combined effects of strain rate and temperature on the flow resistance and deformability of 7075-T6 alloy and confirm that 7075-T6 is well suited to the fabrication of fuel tanks and related structural components in the aerospace field.

  4. Effects of contents of Nb and C on hot deformation behaviors of high Nb X80 pipeline steels

    Institute of Scientific and Technical Information of China (English)

    QIAO Gui-ying; XIAO Fu-ren; ZHANG Xiao-bing; CAO Ya-bin; LIAO Bo

    2009-01-01

    The behavior of the flow deformation and the effects of contents of Nb and C on deformation behaviors of high Nb X80 pipeline steels during hot compression deformation were studied by thermal simulation test.The content of solid solution Nb was quantificationally studied during the reheating and hot deformation process,and the effects of change of solid solution Nb in steels on hot deformation behaviors were discussed.The results show that the contents of Nb and C have great effects on the flow stress behaviors of high Nb X80 pipeline steels.When the C content in steels is constant,the recrystallization activation energy increases from 387 to 481 kJ/mol with increasing the Nb from 0.082% to 0.13% (mass fraction).However,the effect of Nb is correlative to the C content,I.e.w(Nb)/w(C).When w(Nb)/w(C) decreases from 3.61 to 2.18,the recrystallization activation energy decreases from 481 to 434 kJ/mol.

  5. Flow Behavior and Evolution of Microstructure during Hot Deformation for a High Mo Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The mechanical behaviors of high Mo austenitic stainless steel 00Cr20Ni18Mo6Cu[N] have been investigated using the methods of hot compression simulation test on the Thermecmaster-Z simulator. The dynamic recrystallization kinetic equation was established, Avrami coefficient n lies in between 0.9~2 depending on deformation parameters. A perfect flow stress model considering dynamic recrystallization was also established. Dynamic recrystallization tends to complete at 1050℃ and high strain rate, but at temperature below 950℃, it is hard to occur. Double-stage interrupt compression tests were carried out. Activation energy for static and metadynamic recrystallization have been obtained respectively (QSRX=483.7, QMDRX=253.5 k J/mol). Avrami coefficient of MDRX is about 0.5, and t0.5-kinetics equations of SRX and MDRX have also been constructed. The evolution of microstructures during interrupt compression deformation was investigated. Static and metadynamic recrystallizationis essential to improve plasticity, at temperature above 1000℃ increasing interpass time has advantage for static and metadynamic recrystallization.

  6. Hot deformation behavior of medium carbon V-N microalloyed steel

    Institute of Scientific and Technical Information of China (English)

    XU Lei; WANG Cheng-yang; LIU Guo-quan; BAI Bing-zhe

    2009-01-01

    Processing maps for a medium carbon V-N microalloyed steel(designated as VN steel) and a medium carbon V-N bared steel(designated as Non-VN steel) were developed to study the hot deformation behavior and the influence of vanadium and nitrogen,in the temperature range of 750-1 100 ℃ and strain rate range of 0.005-30 s~(-1).Experimental results show that the processing map for the VN steel exhibits two dynamic recrystallization and three instability domains,while that for the Non-VN steel has one dynamic recrystallization and three instability domains.The instability domains of VN steel are larger than those of the Non-VN steel,and the VN steel is easier to be unstable when being hot deformed at high temperature and high stain rate.The addition and precipitation of vanadium and nitrogen can hinder the dynamic recrystallization.Compared with the Non-VN steel,the VN steel has higher dynamic recrystallization critical strain and the corresponding stress.

  7. Hot tensile deformation behavior of twin roll casted 7075 aluminum alloy

    Science.gov (United States)

    Wang, Lei; Yu, Huashun; Lee, Yunsoo; Kim, Hyoung-Wook

    2015-09-01

    High temperature deformation behavior of the 7075 aluminum alloy sheets fabricated by twin roll casting and rolling was investigated by hot tensile tests at different temperatures from 350 to 500 °C and various initial strain rates from 1×10-3 to 1×10-2 s-1. The results show that flow stress increased with increasing initial strain rate and decreasing deformation temperature. A large elongation of 200% was obtained at relatively high strain rate of 5×10-3 s-1 at 450 °C. It is closely related with the grain boundary sliding at elevated temperature attributed to the recrystallized fine grains and the large volume fraction of high-angle grain boundaries. The fracture transformation mechanism changes from ductile transgranular fracture to ductile intergranular fracture due to the recrystallized fine grains at high temperature. High density and uniform cavities observed in large elongation samples at high temperature reveals the contribution of grain boundary sliding. Necking-controlled failure mode was characterized by rare cavities with low elongation.

  8. Investigation of Hot Deformation Behavior of Duplex Stainless Steel Grade 2507

    Science.gov (United States)

    Kingklang, Saranya; Uthaisangsuk, Vitoon

    2016-10-01

    Recently, duplex stainless steels (DSSs) are being increasingly employed in chemical, petro-chemical, nuclear, and energy industries due to the excellent combination of high strength and corrosion resistance. Better understanding of deformation behavior and microstructure evolution of the material under hot working process is significant for achieving desired mechanical properties. In this work, plastic flow curves and microstructure development of the DSS grade 2507 were investigated. Cylindrical specimens were subjected to hot compression tests for different elevated temperatures and strain rates by a deformation dilatometer. It was found that stress-strain responses of the examined steel strongly depended on the forming rate and temperature. The flow stresses increased with higher strain rates and lower temperatures. Subsequently, predictions of the obtained stress-strain curves were done according to the Zener-Hollomon equation. Determination of material parameters for the constitutive model was presented. It was shown that the calculated flow curves agreed well with the experimental results. Additionally, metallographic examinations of hot compressed samples were performed by optical microscope using color tint etching. Area based phase fractions of the existing phases were determined for each forming condition. Hardness of the specimens was measured and discussed with the resulted microstructures. The proposed flow stress model can be used to design and optimize manufacturing process at elevated temperatures for the DSS.

  9. Tensile deformation and fracture behavior of CuZn5 brass alloy at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Sharififar, M., E-mail: m.sharififar@ut.ac.ir; Akbari Mousavi, S.A.A., E-mail: akbarimusavi@ut.ac.ir

    2014-01-31

    Alpha brass alloys are widely used for production of rectangular waveguides because of their low bulk resistivity. In this paper, the microstructure, tensile deformation and fracture behavior of CuZn5 brass alloy were investigated. The strain rate sensitivity and its relation to post-uniform deformation in tensile test and correlation between strain hardening exponent (n) and temperature were examined. The results show that strain hardening exponent decreases from 0.5 to 0.4 with increase in test temperature from 250 to 450 °C. Tensile fracture mechanisms of as-extruded CuZn5 brass alloy were studied over a range of temperatures from 300 to 450 °C and range of strain rates from 0.01 to 0.4 1/s by means of scanning electron microscope (SEM) and Atomic Force Microscope (AFM). The results show that different fracture mechanisms operate in different temperature and strain rate ranges. While transgranular dimple fracture is dominant at 300 °C and 0.4 1/s, the dominant fracture mechanism at 450 °C and 0.01 1/s is cleavage facets. Precipitations and grain boundary sliding at high temperature may be the mechanism of ductility drop. Dynamic strain ageing (DSA) did not occur since none of the manifestations of DSA are observed.

  10. Investigation of Hot Deformation Behavior of Duplex Stainless Steel Grade 2507

    Science.gov (United States)

    Kingklang, Saranya; Uthaisangsuk, Vitoon

    2017-01-01

    Recently, duplex stainless steels (DSSs) are being increasingly employed in chemical, petro-chemical, nuclear, and energy industries due to the excellent combination of high strength and corrosion resistance. Better understanding of deformation behavior and microstructure evolution of the material under hot working process is significant for achieving desired mechanical properties. In this work, plastic flow curves and microstructure development of the DSS grade 2507 were investigated. Cylindrical specimens were subjected to hot compression tests for different elevated temperatures and strain rates by a deformation dilatometer. It was found that stress-strain responses of the examined steel strongly depended on the forming rate and temperature. The flow stresses increased with higher strain rates and lower temperatures. Subsequently, predictions of the obtained stress-strain curves were done according to the Zener-Hollomon equation. Determination of material parameters for the constitutive model was presented. It was shown that the calculated flow curves agreed well with the experimental results. Additionally, metallographic examinations of hot compressed samples were performed by optical microscope using color tint etching. Area based phase fractions of the existing phases were determined for each forming condition. Hardness of the specimens was measured and discussed with the resulted microstructures. The proposed flow stress model can be used to design and optimize manufacturing process at elevated temperatures for the DSS.

  11. A simple higher order shear deformation theory for mechanical behavior of laminated composite plates

    Science.gov (United States)

    Adim, Belkacem; Daouadji, Tahar Hassaine; Rabahi, Aberezak

    2016-06-01

    In the present study, the static, buckling, and free vibration of laminated composite plates is examined using a refined shear deformation theory and developed for a bending analysis of orthotropic laminated composite plates. These models take into account the parabolic distribution of transverse shear stresses and satisfy the condition of zero shear stresses on the top and bottom surfaces of the plates. The most interesting feature of this theory is that it allows for parabolic distributions of transverse shear stresses across the plate thickness and satisfies the conditions of zero shear stresses at the top and bottom surfaces of the plate without using shear correction factors. The number of independent unknowns in the present theory is four, as against five in other shear deformation theories. In the analysis, the equation of motion for simply supported thick laminated rectangular plates is obtained through the use of Hamilton's principle. The accuracy of the analysis presented is demonstrated by comparing the results with solutions derived from other higher order models and with data found in the literature. It can be concluded that the proposed theory is accurate and simple in solving the static, the buckling, and free vibration behaviors of laminated composite plates.

  12. Deformation behavior of two continuously cooled vanadium microalloyed steels at liquid nitrogen temperature

    Directory of Open Access Journals (Sweden)

    Glišić Dragomir M.

    2013-01-01

    Full Text Available The aim of this work was to establish deformation behaviour of two vanadium microalloyed medium carbon steels with different contents of carbon and titanium by tensile testing at 77 K. Samples were reheated at 1250°C/30 min and continuously cooled at still air. Beside acicular ferrite as dominant morphology in both microstructures, the steel with lower content of carbon and negligible amount of titanium contains considerable fraction of grain boundary ferrite and pearlite. It was found that Ti-free steel exhibits higher strain hardening rate and significantly lower elongation at 77 K than the fully acicular ferrite steel. The difference in tensile behavior at 77 K of the two steels has been associated with the influence of the pearlite, together with higher dislocation density of acicular ferrite. [Projekat Ministarstva nauke Republike Srbije, br. OI174004

  13. Temperature dependence of the deformation behavior of 316 stainless steel after low temperature neutron irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Pawel-Robertson, J.E.; Rowcliffe, A.F.; Grossbeck, M.L. [Oak Ridge National Lab., TN (United States)] [and others

    1996-10-01

    The effects of low temperature neutron irradiation on the tensile behavior of 316 stainless steel have been investigated. A single heat of solution annealed 316 was irradiated to 7 and 18 dpa at 60, 200, 330, and 400{degrees}C. The tensile properties as a function of dose and as a function of temperature were examined. Large changes in yield strength, deformation mode, strain to necking, and strain hardening capacity were seen in this irradiation experiment. The magnitudes of the changes are dependent on both irradiation temperature and neutron dose. Irradiation can more than triple the yield strength over the unirradiated value and decrease the strain to necking (STN) to less than 0.5% under certain conditions. A maximum increase in yield strength and a minimum in the STN occur after irradiation at 330{degrees}C but the failure mode remains ductile.

  14. Effects of twin and stacking faults on the deformation behaviors of Al nanowires under tension loading

    Institute of Scientific and Technical Information of China (English)

    An Min-Rong; Song Hai-Yang; Su Jin-Fang

    2012-01-01

    The effects of twin spacing and temperature on the deformation behavior of nanotwinned A1 under tensile loading are investigated using a molecular dynamic (MD) simulation method. The result shows that the yield strength of nanotwinned A1 decreases with the increase of twin spacing,which is related to the repulsive force between twin boundary and the dislocation. The result also shows that there is no strain-hardening at the yield point. On the contrary,the stress is raised by strain hardening in the plastic stage.In addition,we also investigate the effects of stacking fault thickness and temperature on the yield strength of the Al nanowire.The simulation results indicate that the stacking fault may strengthen the A1 nanowire when the thickness of the stacking fault is below a critical value.

  15. Hot deformation behavior and flow stress model of F40MnV steel

    Institute of Scientific and Technical Information of China (English)

    WANG Jin; CHEN Jun; ZHAO Zhen; RUAN Xue-yu

    2007-01-01

    Single hit compression tests were performed at 1 223-1 473 K and strain rate of 0.1-10 s-1 to study hot deformation behavior and flow stress model of F40MnV steel. The dependence of the peak stress, initial stress, saturation stress, steady state stress and peak stain on Zener-Hollomon parameter were obtained. The mathematical models of dynamic recrystallization fraction and grain size were also obtained. Based on the tested data.the flow stress model of F40MnV steel was established in dynamic recovery region and dynamic recrystallization region, respectively. The results show that the activation energy for dynamic recrystallization is 278.6 kJ/mol by regression analysis. The flow stress model of F40MnV steel is proved to approximate the tested data and suitable for numerical simulation of hot forging.

  16. Study on the Deformation Behavior of Mg-3.6%Er Magnesium Alloy

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The deformation behaviour of a casting Mg-3.6%Er magnesium alloy after T6 treatment was studied in tensile tests from room temperature to 450 ℃ under different strain rates ranging from 1.0×10-4 to 6.0×10-3 s-1.Obtained local plateau in the temperature dependence of the ultimate strength (σ b) and yield strength (σ 0.2) under constant strain rate indicated the presence of dynamic strain ageing (DSA).Serrated flow was observed at the temperature of 200, 250, and 300 ℃.The observed negative strain rate sensitivity suggested that the serrated flow behavior arose from DSA.The temperature and strain rate dependence of the critical strain for the onset of serrated flow was analyzed using a phenomenological DSA equation, and the apparent activation energy Q for the serrated flow was obtained by calculation.

  17. HOT DEFORMATION AND MARTENSITIC TRANSFORMATION BEHAVIORS OF Fe-32%Ni ALLOY

    Institute of Scientific and Technical Information of China (English)

    J. Huang; Z.Xu

    2006-01-01

    The Hot deformation and martensitic transformation behaviors of Fe-32% Ni alloy was investigated by measurements of electrical resistance and X-ray diffraction. With the increase in strain,the austenite goes through from the work-hardened to the partial dynamically re-crystallized and then to the completed dynamically re-crystallized. The martensitic transformation characteristics depend on the austenite states. The work-hardening in small strain is helpful to martensitic transformation due to the low dislocation density and little lattice distortion, while the high dislocation density and severe lattice distortion by the increase in strain will hinder the martensitic nucleation.Once dynamic re-crystallization (DRX) takes place, the martensitic transformation will be enhanced again, which is related to the heterogeneous dynamic substructures. The growing DRX grain can enhance the martensitic nucleation due to the low dislocation density near its grain boundary.

  18. Hot deformation behaviors and flow stress model of GCr15 bearing steel

    Institute of Scientific and Technical Information of China (English)

    LIAO Shu-lun; ZHANG Li-wen; YUE Chong-xiang; PEI Ji-bin; GAO Hui-ju

    2008-01-01

    The hot deformation behaviors of GCr15 bearing steel were investigated by isothermal compression tests, performed on a Gleeble-3800 thermal-mechanical simulator at temperatures between 950℃ and 1 150 ℃ and strain rates between 0.1 and 10s-1.The peak stress and peak strain as functions of processing parameters were obtained. The dependence of peak stress on strain rate and temperature obeys a hyperbolic sine equation with a Zener-Hollomon parameter. By regression analysis, in the temperature range of 950-1150℃ and strain rate range of 0.1-10 s-1, the mean activation energy and the stress exponent were determined to be 351kJ/mol and 4.728, respectively. Meanwhile, models of flow stress and dynamic recrystallization (DRX) grain size were also established. The model predictions show good agreement with experimental results.

  19. Deformation behavior and microstructural evolution of nanocrystalline aluminum alloys and composites

    Science.gov (United States)

    Ahn, Byungmin

    routes. Strain rate sensitivity in room temperature deformation was examined as a function of grain size using nanoindentation. Negative strain rate sensitivity was observed in nanocrystalline and ultrafine-grained materials, while a conventional alloy was strain rate insensitive. For multi-scale materials, local displacements in bimodal materials during tensile deformation were measured by digital image correlation. Inhomogeneous strain behavior was observed between nanocrystalline and coarse-grained regions and attributed to differences in dislocation plasticity. In the Al matrix nanocomposite with hybrid microstructures, microstructural evolution of the composite powder with boron-carbide reinforcements was investigated as a function of milling time.

  20. Constitutive Analysis and Hot Deformation Behavior of Fine-Grained Mg-Gd-Y-Zr Alloys

    Science.gov (United States)

    Alizadeh, R.; Mahmudi, R.; Ruano, O. A.; Ngan, A. H. W.

    2017-09-01

    Mg-Gd-Y-Zr alloys are among the newly developed magnesium alloys with superior strength properties at elevated temperatures. Accordingly, the hot shear deformation behavior of fine-grained extruded Mg-9Gd-4Y-0.4Zr (GWK940), Mg-5Gd-4Y-0.4Zr (GWK540), and Mg-5Gd-0.4Zr (GK50) alloys was investigated using the localized shear punch testing (SPT) method. Shear punch tests were performed at 573 K, 623 K, 673 K, 723 K, and 773 K (300 °C, 350 °C, 400 °C, 450 °C, and 500 °C) under shear strain rates in the range of 6.7 × 10-3 to 6.7 × 10-2 s-1. The new fitting method of Rieiro, Carsi, and Ruano was used for direct calculation of the Garofalo constants. It was concluded that the Garofalo equation can be used satisfactorily for describing the deformation behavior of the alloys in the entire studied ranges of strain rates and temperatures. In addition, stability maps were obtained by calculations based on the Lyapunov criteria using the Garofalo constants. The predicted stability ranges of temperature and strain rate were similar for the studied alloys. At an intermediate strain rate of 0.05 s-1, the optimal temperature at which a stable region is expected was found to be 648 K to 673 K (375 °C to 400 °C) for all three materials. The most pronounced effect of the Gd and Y elements was to enhance the high-temperature strength of the alloys.

  1. Biomechanical behaviors of dragonfly wing:relationship between configuration and deformation

    Institute of Scientific and Technical Information of China (English)

    Ren Huai-Hui; Wang Xi-Shu; Chen Ying-Long; Li Xu-Dong

    2012-01-01

    In this paper,the natural structures of a dragonfly wing,including the corrugation of the chordwise cross-section,the sandwich microstructure veins,and the junctions between the vein and the membrane,have been investigated with experimental observations,and the morphological parameters of these structural features are measured. The experimental result indicates that the corrugated angle among the longitudinal veins ranges from 80° to 150°,and the sandwiched microstructure vein mainly consists of chitin and protein layers.Meanwhile,different finite element models,which include models I and I* for the planar forewings,models Ⅱ and Ⅱ* for the corrugated forewings,and a submodel with solid veins and membranes,are created to investigate the effects of these structural features on the natural frequency/modal,the dynamical behaviors of the flapping flight,and the deformation mechanism of the forewings.The numerical results indicate that the corrugated forewing has a more reasonable natural frequency/modal,and the first order up-down flapping frequency of the corrugated wing is closer to the experimental result (about 27.00 Hz),which is significantly larger than that of the planar forewing (10.94 Hz).For the dynamical responses,the corrugated forewing has a larger torsional angle than the planar forewing,but a lower flapping angle.In addition,the sandwich microstructure veins can induce larger amplitudes of torsion deformation,because of the decreasing stiffness of the whole forewing.For the submodel of the forewing,the average stress of the chitin layer is much larger than that of the protein layer in the longitudinal veins.These simulative methods assist us to explain the flapping flight mechanism of the dragonfly and to design a micro aerial vehicle by automatically adjusting the corrugated behavior of the wing.

  2. From particle simulations to macroscopic constitutive relations

    NARCIS (Netherlands)

    Göncü, F.; Luding, S.

    2010-01-01

    The goal is to determine the constitutive behavior of granular packings under various deformations (isotropic and anisotropic) from particle simulations. For this we consider deformations, stress, structure and the contact forces as the basis. In a previous study [6,7] we investigated using DEM, the

  3. The effect of elevated temperature on the inelastic deformation behavior of PMR-15 solid polymer

    Science.gov (United States)

    Ryther, Chad E. C.

    The inelastic deformation behavior of PMR-15 neat resin, a high-temperature thermoset polymer, was investigated at temperatures in the 274--316 °C range. The experimental program was developed to explore the influence of temperature on strain-controlled tensile loading, relaxation and creep behaviors. The experimental results clearly demonstrate that the mechanical behavior of PMR-15 polymer exhibits a strong dependence on temperature. During strain-controlled tensile loading, the slope of the stress-strain curve in the quasi-elastic region decreases and the slope of the stress-strain curve in the flow stress region increases with increasing temperature. At a given strain rate, the flow stress level decreases with increasing temperature. Furthermore, the transition from quasi-elastic behavior to inelastic flow becomes less pronounced with increasing temperature. During relaxation, the amount of the stress drop for a given prior strain rate decreases with increasing temperature. At a given prior strain rate and creep stress level, increasing temperature results in increased creep strain accumulation. Based on the experimental results the Viscoplasticity Based on Overstress for Polymers (VBOP) theory was augmented to account for the effects of elevated temperature. Several model parameters were determined to depend on temperature. Those parameters were developed into functions of temperature. The augmented VBOP was then employed to predict the response of the PMR-15 polymer under various test histories at temperatures in the 274--316 °C range. An enhanced procedure for determining VBOP model parameters that utilizes a McLean type dip test to assess the equilibrium stress was developed. Model predictions were considerably improved by employing an enhanced model characterization procedure. Additionally, the effects of prior isothermal aging at various temperatures in the 260--316 °C range on the inelastic deformation behavior of PMR-15 at 288 °C were evaluated. For

  4. Deformation behavior in reactor pressure vessel steels as a clue to understanding irradiation hardening.

    Energy Technology Data Exchange (ETDEWEB)

    DiMelfi, R. J.; Alexander, D. E.; Rehn, L. E.

    1999-10-25

    post-yield hardening rate is clearly greater than that of the unirradiated material, and the flow curves cannot be made to superimpose. The binary iron-base model alloys studied here show a less pronounced difference in flow behavior for neutrons and electrons than exhibited by the steels, implicating the effect of alloy chemistry. Our results are analyzed in the context of classical theories dealing with the interaction between the deformation microstructure, i.e. glide dislocations, and irradiation-produced defects. Our findings provide clues about the way different alloy constituents interact with the different kinds of irradiation damage to strengthen the material differently.

  5. A Study of Hardening Behavior Based on a Finite-Deformation Gradient Crystal-Plasticity Model

    CERN Document Server

    Pouriayevali, Habib

    2016-01-01

    A systematic study on the different roles of the governing components of a well-defined finite-deformation gradient crystal-plasticity model proposed by (Gurtin, 2008b) is carried out, in order to visualize the capability of the model in the prediction of a wide range of hardening behaviors as well as rate-dependent, scale-variation and Bauschinger-like responses in a single crystal. A function of accumulation rates of dislocations is employed and viewed as a measure of formation of short-range interactions which impede dislocation movements within a crystal. The model is first represented in the reference configuration for the purpose of numerical implementation, and then implemented in the FEM software ABAQUS via a user-defined subroutine (UEL). Our simulation results reveal that the dissipative gradient-strengthening is also identified as a source of isotropic-hardening behavior, which represents the effect of cold work introduced by (Gurtin and Ohno, 2011). Moreover, plastic flows in predefined slip syste...

  6. The macroscopic pancake bounce

    Science.gov (United States)

    Andersen Bro, Jonas; Sternberg Brogaard Jensen, Kasper; Nygaard Larsen, Alex; Yeomans, Julia M.; Hecksher, Tina

    2017-01-01

    We demonstrate that the so-called pancake bounce of millimetric water droplets on surfaces patterned with hydrophobic posts (Liu et al 2014 Nat. Phys. 10 515) can be reproduced on larger scales. In our experiment, a bed of nails plays the role of the structured surface and a water balloon models the water droplet. The macroscopic version largely reproduces the features of the microscopic experiment, including the Weber number dependence and the reduced contact time for pancake bouncing. The scalability of the experiment confirms the mechanisms of pancake bouncing, and allows us to measure the force exerted on the surface during the bounce. The experiment is simple and inexpensive and is an example where front-line research is accessible to student projects.

  7. Strain-hardening and warm deformation behaviors of extruded Mg–Sn–Yb alloy sheet

    Directory of Open Access Journals (Sweden)

    Jing Jiang

    2014-06-01

    Full Text Available Strain-hardening and warm deformation behaviors of extruded Mg–2Sn–0.5Yb alloy (at.% sheet were investigated in uniaxial tensile test at temperatures of 25–250 °C and strain rates of 1 × 10−3 s−1–0.1 s−1. The data fit with the Kocks–Mecking type plots were used to show different stages of strain hardening. Besides III-stage and IV-stage, the absence of the II-stage strain hardening at room temperature should be related to the sufficient dynamic recrystallization during extrusion. The decrease of strain hardening ability of the alloy after yielding was attributed to the reduction of dislocation density with increasing testing temperature. Strain rate sensitivity (SRS was significantly enhanced with increasing temperature, and the corresponding m-value was calculated as 0.07–0.12, which indicated that the deformation mechanism was dominated by the climb-controlled dislocation creep at 200 °C. Furthermore, the grain boundary sliding (GBS was activated at 250 °C, which contributed to the higher SRS. The activation energy was calculated as 213.67 kJ mol−1, which was higher than that of lattice diffusion or grain boundary self-diffusion. In addition, the alloy exhibited a quasi superplasticity at 250 °C with a strain rate of 1 × 10−3 s−1, which was mainly related to the fine microstructure and the presence of the Mg2Sn and Mg2(Sn,Yb particles.

  8. Cyclic Deformation Behavior of a Rare-Earth Containing Extruded Magnesium Alloy: Effect of Heat Treatment

    Science.gov (United States)

    Mirza, F. A.; Chen, D. L.; Li, D. J.; Zeng, X. Q.

    2015-03-01

    The present study was aimed at evaluating strain-controlled cyclic deformation behavior of a rare-earth (RE) element containing Mg-10Gd-3Y-0.5Zr (GW103K) alloy in different states (as-extruded, peak-aged (T5), and solution-treated and peak-aged (T6)). The addition of RE elements led to an effective grain refinement and weak texture in the as-extruded alloy. While heat treatment resulted in a grain growth modestly in the T5 state and significantly in the T6 state, a high density of nano-sized and bamboo-leaf/plate-shaped β' (Mg7(Gd,Y)) precipitates was observed to distribute uniformly in the α-Mg matrix. The yield strength and ultimate tensile strength, as well as the maximum and minimum peak stresses during cyclic deformation in the T5 and T6 states were significantly higher than those in the as-extruded state. Unlike RE-free extruded Mg alloys, symmetrical hysteresis loops in tension and compression and cyclic stabilization were present in the GW103K alloy in different states. The fatigue life of this alloy in the three conditions, which could be well described by the Coffin-Manson law and Basquin's equation, was equivalent within the experimental scatter and was longer than that of RE-free extruded Mg alloys. This was predominantly attributed to the presence of the relatively weak texture and the suppression of twinning activities stemming from the fine grain sizes and especially RE-containing β' precipitates. Fatigue crack was observed to initiate from the specimen surface in all the three alloy states and the initiation site contained some cleavage-like facets after T6 heat treatment. Crack propagation was characterized mainly by the characteristic fatigue striations.

  9. Tensile Deformation Behavior of Fe-Mn-Al-C Low Density Steels

    Institute of Scientific and Technical Information of China (English)

    Xiao-feng ZHANG; Hao YANG; De-ping LENG; Long ZHANG; Zhen-yi HUANG; Guang CHEN

    2016-01-01

    Room temperature tensile tests of Fe-Mn-Al-C low density steels with four different chemical compositions were conducted to clarify the dominant deformation mechanisms.Parameters like product of strength and elongation, as well as specific strength and curves of stress-strain relations were calculated.The microstructures and tensile frac-ture morphologies were observed by optical microscope,scanning electron microscope and transmission electron mi-croscope.The tensile behavior of low density steel was correlated to the microstructural evolution during plastic de-formation,and the effects of elements,cooling process and heat treatment temperature on the mechanical properties of the steels were analyzed.The results show that the tensile strength of steels with different cooling modes is more than 1 000 MPa.The highest tensile strength of 28Mn-12Al alloy reached 1 230 MPa,with corresponding specific strength of 189.16 MPa.cm3 .g-1 ,while the specific strength of 28Mn-10Al alloy was 178.98 MPa.cm3 .g-1 , and the excellent product of strength and elongation of 28Mn-8Al alloy was over 69.2 GPa.%.A large number of ferrite reduced the ductility and strain hardening rate of the alloy,while the existence ofκcarbides may improve the strength but weaken the plasticity.Some fineκcarbides appeared in the water-quenched specimen,while coarseκcarbides were observed in the air-cooled specimen.High temperature heat treatment improved the decomposition ki-netics ofγphase and the diffusion rate of carbon,thus speeded up the precipitation of fineκcarbides.The dominant deformation mechanism of low density steel was planar glide,including shear-band-induced plasticity and microband-induced plasticity.

  10. In situ characterization of the deformation and failure behavior of non-stochastic porous structures processed by selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Gorny, B.; Niendorf, T.; Lackmann, J. [Lehrstuhl fuer Werkstoffkunde (Materials Science), University of Paderborn, Pohlweg 47-49, 33098 Paderborn (Germany); Thoene, M.; Troester, T. [Lehrstuhl fuer Leichtbau im Automobil (Automotive Lightweight Construction), University of Paderborn, Pohlweg 47-49, 33098 Paderborn (Germany); Direct Manufacturing Research Center (DMRC), Mersinweg 3, 33098 Paderborn (Germany); Maier, H.J., E-mail: hmaier@mail.upb.de [Lehrstuhl fuer Werkstoffkunde (Materials Science), University of Paderborn, Pohlweg 47-49, 33098 Paderborn (Germany)

    2011-10-15

    Highlights: {yields} The present study focused on deformation behavior and failure mechanisms in lattice structure produced by selective laser melting (SLM). {yields} It is demonstrated that heat treatments can be used to increase the energy absorption of an SLM-processed structure. {yields} An in situ testing procedure was introduced, where local strains were calculated by digital image correlation {yields} Shear failure could be predicted by localization using Tresca strains. {yields} The approach employed provides a means to understand the microstructure-mechanical property-local deformation relationship. - Abstract: Cellular materials are promising candidates for load adapted light-weight structures. Direct manufacturing (DM) tools are effective methods to produce non-stochastic structures. Many DM studies currently focus on optimization of the geometric nature of the structures obtained. The literature available so far reports on the mechanical properties but local deformation mechanisms are not taken into account. In order to fill this gap, the current study addresses the deformation behavior of a lattice structure produced by selective laser melting (SLM) on the local scale by means of a comprehensive experimental in situ approach, including electron backscatter diffraction, scanning electron microscopy and digital image correlation. SLM-processed as well as heat treated lattice structures made from TiAl6V4 alloy were employed for mechanical testing. It is demonstrated that the current approach provides means to understand the microstructure-mechanical property-local deformation relationship to allow for optimization of load adapted lattice structures.

  11. Deformed General Relativity

    CERN Document Server

    Bojowald, Martin

    2013-01-01

    Deformed special relativity is embedded in deformed general relativity using the methods of canonical relativity and loop quantum gravity. Phase-space dependent deformations of symmetry algebras then appear, which in some regimes can be rewritten as non-linear Poincare algebras with momentum-dependent deformations of commutators between boosts and time translations. In contrast to deformed special relativity, the deformations are derived for generators with an unambiguous physical role, following from the relationship between canonical constraints of gravity with stress-energy components. The original deformation does not appear in momentum space and does not give rise to non-locality issues or problems with macroscopic objects. Contact with deformed special relativity may help to test loop quantum gravity or restrict its quantization ambiguities.

  12. Canonical quantization of macroscopic electromagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Philbin, T G, E-mail: tgp3@st-andrews.ac.u [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)

    2010-12-15

    Application of the standard canonical quantization rules of quantum field theory to macroscopic electromagnetism has encountered obstacles due to material dispersion and absorption. This has led to a phenomenological approach to macroscopic quantum electrodynamics where no canonical formulation is attempted. In this paper macroscopic electromagnetism is canonically quantized. The results apply to any linear, inhomogeneous, magnetodielectric medium with dielectric functions that obey the Kramers-Kronig relations. The prescriptions of the phenomenological approach are derived from the canonical theory.

  13. Canonical quantization of macroscopic electromagnetism

    CERN Document Server

    Philbin, T G

    2010-01-01

    Application of the standard canonical quantization rules of quantum field theory to macroscopic electromagnetism has encountered obstacles due to material dispersion and absorption. This has led to a phenomenological approach to macroscopic quantum electrodynamics where no canonical formulation is attempted. In this paper macroscopic electromagnetism is canonically quantized. The results apply to any linear, inhomogeneous, magnetoelectric medium with dielectric functions that obey the Kramers-Kronig relations. The prescriptions of the phenomenological approach are derived from the canonical theory.

  14. Multi-axial load application and DIC measurement of advanced composite beam deformation behavior

    Directory of Open Access Journals (Sweden)

    Berggreen C.

    2010-06-01

    Full Text Available For the validation of a new beam element formulation, a wide set of experimental data consisting of deformation patterns obtained for a number of specially designed composite beam elements, have been obtained. The composite materials applied in the beams consist of glass-fiber reinforced plastic with specially designed layup configurations promoting advanced coupling behavior. Furthermore, the beams are designed with different cross-section shapes. The data obtained from the experiments are also used in order to improve the general understanding related to practical implementation of mechanisms of elastic couplings due to anisotropic properties of composite materials. The knowledge gained from these experiments is therefore essential in order to facilitate an implementation of passive control in future large wind turbine blades. A test setup based on a four-column MTS servo-hydraulic testing machine with a maximum capacity of 100 kN was developed, see Figure 1. The setup allows installing and testing beams of different cross-sections applying load cases such as axial extension, shear force bending, pure bending in two principal directions as well as pure torsion, see Figure 2. In order to apply multi-axial loading, a load application system consisting of three hydraulic actuators were mounted in two planes using multi-axial servo-hydraulic control. The actuator setup consists of the main actuator on the servo-hydraulic test machine working in the vertical axis (depicted on Figure 1 placed at the testing machine crosshead and used for application of vertical forces to the specimens. Two extra actuators are placed in a horizontal plane on the T-slot table of the test machine in different positions in order to apply loading at the tip of the specimen in various configurations. In order to precisely characterize the global as well as surface deformations of the beam specimens tested, a combination of different measurement systems were used during

  15. Quasi-static tensile deformation and fracture behavior of a highly particle-filled composite using digital image correlation method

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Polymer bonded explosives (PBXs) are highly particle-filled composite materials.This paper experimentally studies the tensile deformation and fracture behavior of a PBX simulation by using the semi-circular bending (SCB) test.The deformation and fracture process of a pre-notched SCB sample with a random speckle pattern is recorded by a charge coupled device camera.The displacement and strain fields on the observed surface during the loading process are obtained by using the digital image correlation method....

  16. Finite deformation analysis of continuum structures with time dependent anisotropic elastic plastic material behavior (LWBR/AWBA Development Program)

    Energy Technology Data Exchange (ETDEWEB)

    Hutula, D.N.

    1980-03-01

    A finite element procedure is presented for finite deformation analysis of continuum structures with time-dependent anisotropic elastic-plastic material behavior. An updated Lagrangian formulation is used to describe the kinematics of deformation. Anisotropic constitutive relations are referred, at each material point, to a set of three mutually orthogonal axes which rotate as a unit with an angular velocity equal to the spin at the point. The time-history of the solution is generated by using a linear incremental procedure with residual force correction, along with an automatic time step control algorithm which chooses time step sizes to control the accuracy and numerical stability of the solution.

  17. Effect of zinc crystals size on galvanized steel deformation and electrochemical behavior

    Directory of Open Access Journals (Sweden)

    José Daniel Culcasi

    2009-09-01

    Full Text Available Hot-dip galvanized steel sheets with different spangle sizes were deformed by means of rolling and tension. The change of preferential crystallographic orientation and of superficial characteristics due to the deformation was analyzed by means of both X-rays diffraction and optical and scanning electronic microscopy. A correlation between such changes and the involving deformation modes was intended to be done and the spangle size influence on these modes was studied. Coating reactivity change due to the deformation was investigated by means of quasi-steady DC electrochemical tests. The results allow to infer that, in great spangle samples, the main deformation mechanism is twinning whereas in small spangle ones, pyramidal slip systems happen as well. The increase of the reactivity with the deformation is greater in tension than in rolling and it is more important in small than in great spangle samples.

  18. Deformation behavior of SiC particle reinforced Al matrix composites based on EMA model

    Institute of Scientific and Technical Information of China (English)

    CHENG Nan-pu; ZENG Su-min; YU Wen-bin; LIU Zhi-yi; CHEN Zhi-qian

    2007-01-01

    Effects of the matrix properties, particle size distribution and interfacial matrix failure on the elastoplastic deformation behavior in Al matrix composites reinforced by SiC particles with an average size of 5 μm and volume fraction of 12% were quantitatively calculated by using the expanded effective assumption(EMA) model. The particle size distribution naturally brings about the variation of matrix properties and the interfacial matrix failure due to the presence of SiC particles. The theoretical results coincide well with those of the experiment. The current research indicates that the load transfer between matrix and reinforcements, grain refinement in matrix, and enhanced dislocation density originated from the thermal mismatch between SiC particles and Al matrix increase the flow stress of the composites, but the interfacial matrix failure is opposite. It also proves that the load transfer, grain refinement and dislocation strengthening are the main strengthening mechanisms, and the interfacial matrix failure and ductile fracture of matrix are the dominating fracture modes in the composites. The mechanical properties of the composites strongly depend on the metal matrix.

  19. Plastic deformation behavior of Fe–Co–B–Si–Nb–Cr bulk metallic glasses under nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.T.; Hong, S.H.; Lee, C.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Park, J.M., E-mail: jinman_park@hotmail.com [Materials Research Center, Samsung Advanced Institute of Technology (SAIT), San 14-1, Nongseo-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of); Kim, T.W.; Lee, W.H. [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of); Yim, H.I. [Department of Physics, Sookmyung Women’s University, Hyochangwongil 52, Yongsan-ku, Seoul 140-742 (Korea, Republic of); Kim, K.B., E-mail: kbkim@sejong.ac.kr [HMC, Faculty of Nanotechnology and Advanced Materials Engineering, Sejong University, 98 Gunja-dong, Gwangjin-gu, Seoul 143-747 (Korea, Republic of)

    2014-02-25

    Highlights: • Additional Cr modulation of atomic structure of Fe-Co-B-Si-Nb BMGs. • An amount of free volume characterized by a combination of nanoindentation and AFM. • Free volume determined by height measurement of AFM after nanoindentation. -- Abstract: In this work, we investigate the effect of Cr addition on thermal properties and indentation behavior of Fe{sub 52}Co{sub 20−x}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub x} alloys with x = 0, 1, 3 and 5 at.%, respectively. Among all studied alloys, the Fe{sub 52}Co{sub 17}B{sub 20}Si{sub 4}Nb{sub 4}Cr{sub 3} bulk metallic glass (BMG) exhibits the highest thermal stability with large supercooled liquid region of 40 K and the pronounced plastic deformation features which is serrated flow (pop-in event) and significant pile-up of materials around indents. This demonstrates that the appropriate addition of Cr in Fe-based BMG can induce the internal atomic structure modulation and promote the mechanical softening, which are discussed in terms of free volume concept.

  20. OBSERVATIONS ON DEFORMATION BEHAVIOR OF HIGH PERFORMANCE FIBERS BY POLARIZING OPTICAL MICROSCOPY

    Institute of Scientific and Technical Information of China (English)

    Chang-fa Xiao; Yu-feng Zhang

    2000-01-01

    By means of polarizing optical microscopy (POM), deformation behavior of four kinds of fibers, i.e. ultra high molecular weight polyethylene (UHMW-PE) fiber, polyvinyl alcohol (PVA) fiber, polyethylene terephthalate (PET) fiber,and wholly aromatic (p-hydroxybenzoic acid/2-hydroxy-6-naphthoic acid) copolyester [P(HBA/HNA)]/PET (ACPET blend) fiber, in axial compression, axial impacting, and bending was observed. In compression, kink bands formed at an angle of 55~60° to the fiber axis in 10-times-drawn UHMW-PE fiber, 75~80° in 40-times-drawn sample, 80° in PVA fiber, and 90°in the ACPET blend fiber. In impacting and bending, band angles of UHMW-PE, PVA and PET fibers are nearly the same as those formed in compression, indicating that slip systems do not change. For any of the four kinds of fiber, band spacing exhibits great differences in compression, in impacting, and in bending, which may be attributed to the differences in the degrees of strain or stress concentration.

  1. Cyclic Deformation of Advanced High-Strength Steels: Mechanical Behavior and Microstructural Analysis

    Science.gov (United States)

    Hilditch, Timothy B.; Timokhina, Ilana B.; Robertson, Leigh T.; Pereloma, Elena V.; Hodgson, Peter D.

    2009-02-01

    The fatigue properties of multiphase steels are an important consideration in the automotive industry. The different microstructural phases present in these steels can influence the strain life and cyclic stabilized strength of the material due to the way in which these phases accommodate the applied cyclic strain. Fully reversed strain-controlled low-cycle fatigue tests have been used to determine the mechanical fatigue performance of a dual-phase (DP) 590 and transformation-induced plasticity (TRIP) 780 steel, with transmission electron microscopy (TEM) used to examine the deformed microstructures. It is shown that the higher strain life and cyclic stabilized strength of the TRIP steel can be attributed to an increased yield strength. Despite the presence of significant levels of retained austenite in the TRIP steel, both steels exhibited similar cyclic softening behavior at a range of strain amplitudes due to comparable ferrite volume fractions and yielding characteristics. Both steels formed low-energy dislocation structures in the ferrite during cyclic straining.

  2. Deformation Behavior at High Temperature of Feeder Pipe Material in CANDU

    Energy Technology Data Exchange (ETDEWEB)

    Kim, SungSoo; Lee, Yoon Sang; Kim, Young Suk [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The specification of these nuclear materials is called as a SA106 in pipe shape. The chemical composition of SA106 is same as mild steel. The deformation behavior at high temperature in mild steel is rarely understood yet, although mild steel is a major structural material in commercial nuclear reactors. Thus, the high temperature tensile tests were carried out up to 500℃. The results are properly interpreted in the aspects of the short range order reaction. This paper is concluded as follows. 1. The FC mild steel shows a yield point. at below 400℃, whereas the WQ does not show the yield point. The reason why the yield point appears is due to the destruction of SRO formed during furnace cooling process 2. The serration appears at 50-150℃, at which the exothermic reaction takes place. The origin of the exothermic reaction is a formation of SRO between Fe and C. 3. The shape of serration changes significantly at above 121℃ and becomes downward generally, this is mainly due to both destruction of SRO by the disordering and by the shearing.

  3. Viscoelasticity behavior for finite deformations, using a consistent hypoelastic model based on Rivlin materials

    Science.gov (United States)

    Altmeyer, Guillaume; Panicaud, Benoit; Rouhaud, Emmanuelle; Wang, Mingchuan; Roos, Arjen; Kerner, Richard

    2016-11-01

    When constructing viscoelastic models, rate-form relations appear naturally to relate strain and stress tensors. One has to ensure that these tensors and their rates are indifferent with respect to the change of observers and to the superposition with rigid body motions. Objective transports are commonly accepted to ensure this invariance. However, the large number of transport operators developed makes the choice often difficult for the user and may lead to physically inconsistent formulation of hypoelasticity. In this paper, a methodology based on the use of the Lie derivative is proposed to model consistent hypoelasticity as an equivalent incremental formulation of hyperelasticity. Both models are shown to be reversible and completely equivalent. Extension to viscoelasticity is then proposed from this consistent model by associating consistent hypoelastic models with viscous behavior. As an illustration, Mooney-Rivlin nonlinear elasticity is coupled with Newton viscosity and a Maxwell-like material is investigated. Numerical solutions are then presented to illustrate a viscoelastic material subjected to finite deformations for a large range of strain rates.

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

    Science.gov (United States)

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

    Directory of Open Access Journals (Sweden)

    Peter Panfilov

    2016-01-01

    Full Text Available 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(PO45OH; 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.

  6. Coping behavior of women with breast cancer with visible postsurgery deformity

    Directory of Open Access Journals (Sweden)

    Sirota N. A.

    2013-01-01

    Full Text Available Research was carried out to explore coping strategies in cancer patients. In all, 70 women with breast cancer were studied: 35 of them had visible postsurgery deformity, and 35 did not have visible postsurgery deformity. The purpose of the research was to uncover their preferences for using various strategies and resources to cope with their illness. The results showed that both groups of women had a special set of strategies for coping with stress. The women with visible postsurgery deformity made significantly less use of resources for coping with their illness than did the subgroup of women without visible postsurgery deformity.

  7. Stress-induced deformation at Ap~Mp and thermal cycling behavior of Cu-Al-Ni single crystals

    Institute of Scientific and Technical Information of China (English)

    陈庆福; 蔡伟; 赵连城

    2001-01-01

    Stress-induced deformation in Ap~Mp and concomitant shape recovery behavior of Cu-13.4Al-4.0Ni single crystals were studied. Abnormal high stress-induced deformation exists in Ap~Mp under the conditions of either heating with load or cooling with load. The recovered deformation is successively composed of four parts, the recoveries from superelasticity, normal reverse transformation, thermally activated reverse transformation of partially stabilized martensite and reverse transformation of stabilized martensite by over-heating. With increasing cycling number, the recovery part from normal reverse transformation decreases, while that from reverse transformation of stabilized martensite by over-heating increases, which shows a typical stabilization of martensite.

  8. Experimental Study on Anisotropic Strength and Deformation Behavior of a Coal Measure Shale under Room Dried and Water Saturated Conditions

    Directory of Open Access Journals (Sweden)

    Jingyi Cheng

    2015-01-01

    Full Text Available This paper presents an experimental investigation of anisotropic strength and deformation behavior of coal measure shale. The effect of two factors (i.e., anisotropy and water content on shale strength and deformation behavior was studied. A series of uniaxial and triaxial compression tests were conducted on both room dried and water saturated samples for different lamination angles. The test results indicate that (1 the compressive strength, cohesion, internal friction angle, tangent Young’s modulus, and axial strain corresponding to the peak and residual strengths of room dried specimens exhibit anisotropic behavior that strongly depends on the orientation angle (β; (2 in comparison to the room dried samples, the compressive strength and Young’s modulus as well as the anisotropy are all reduced for water saturated specimens; and (3 the failure mechanism of the samples can be summarized into two categories: sliding along lamination and shearing of rock material, with the type occurring in a particular situation depending strongly on the lamination orientation angles with respect to the major principal stress. According to the findings, it is strongly recommended that the effect of anisotropy and water content on the strength and deformation behavior of the rock must be considered in ground control designs.

  9. Deformation behavior of Cu-12wt%AI alloy wires with continuous columnar crystals in dieless drawing process

    Institute of Scientific and Technical Information of China (English)

    LIU XueFeng; WU YuHui; XIE JianXin

    2009-01-01

    The microstructure and mechanical properties of Cu-12wt%AI alloy wires which are composed of continuous columnar crystals after dieless drawing forming at drawing speed of 1.0-1.4 mm/s and deformation temperature of 600-900℃ were analyzed,and deformation behavior of the alloy during dieless drawing forming was experimentally investigated.The results showed that in the above-mentioned conditions,recrystallization phenomenon was not found during dieless drawing forming.When a drawing speed of 1.0 mm/s was used,the grain boundaries were out of straight gradually with increasing deformation temperature from 600℃ to 900℃,and tensile strength of the dieless drawn Cu-12wt%AI alloy wires increased while elongations decreased with increasing deformation temperature.At drawing speed of 1.1-1.2 mm/s and deformation temperature of 600℃,the effect of dieless drawing forming process on the microstructure of the alloy was inconspicuous,and when drawing speed was up to 1.3-1.4 mm/s,the grain boundaries of continuous columnar crystals became zigzag while there was little effect of drawing speed of 1.1-1.4 mm/s on the elongation and tensile strength of the alloy wires.

  10. Deformation behavior of Cu-12wt%Al alloy wires with continuous columnar crystals in dieless drawing process

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The microstructure and mechanical properties of Cu-12wt%Al alloy wires which are composed of continuous columnar crystals after dieless drawing forming at drawing speed of 1.0―1.4 mm/s and deformation temperature of 600―900℃ were analyzed, and deformation behavior of the alloy during dieless drawing forming was experimentally investigated. The results showed that in the abovemen-tioned conditions, recrystallization phenomenon was not found during dieless drawing forming. When a drawing speed of 1.0 mm/s was used, the grain boundaries were out of straight gradually with increasing deformation temperature from 600℃ to 900℃, and tensile strength of the dieless drawn Cu-12wt%Al alloy wires increased while elongations decreased with increasing deformation temperature. At drawing speed of 1.1―1.2 mm/s and deformation temperature of 600℃, the effect of dieless drawing forming process on the microstructure of the alloy was inconspicuous, and when drawing speed was up to 1.3―1.4 mm/s, the grain boundaries of continuous columnar crystals became zigzag while there was little effect of drawing speed of 1.1―1.4 mm/s on the elongation and tensile strength of the alloy wires.

  11. In-situ tube burst testing and high-temperature deformation behavior of candidate materials for accident tolerant fuel cladding

    Science.gov (United States)

    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.

  12. Microstructure and Deformation Behavior of Ti-10V-2Fe-3Al Alloy during Hot Forming Process

    Institute of Scientific and Technical Information of China (English)

    GUAN Renguo; ZHAO Zhanyong; Choi KS; Lee CS

    2015-01-01

    The microstructure evolution and formability of Ti-10V-2Fe-3Al alloy related to the initial microstructures and processing variables were investigated during hot forming process. The experimental results show that theα-phase growth is controlled by solute diffusion during the heat treatment processes. Four different microstructures were established by combinations of several heat treatments, and Ti-10V-2Fe-3Al alloy shows excellent formability both above and below theβ transus temperature. The alloy possesses low deformation resistance and active restoration mechanism during the deformation. A constitutive equation describing the hot deformation behavior of Ti-10V-2Fe-3Al alloy was obtained. Higher lfow stress was observed for the acicular morphology ofαphase in microstructures with large aspect ratios as compared with that of small aspect ratios. Due to the dynamic recovery in softβphase, and the dynamic recrystallization and breakage of acicularα-phase, lfow softening occurred signiifcantly during deformation. Dynamic recrystallization also occurred especially in the severely deformed regions of forged parts.

  13. A study on hot deformation behavior of Ni-42.5Ti-7.5Cu alloy

    Energy Technology Data Exchange (ETDEWEB)

    Etaati, Amir, E-mail: amir.etaati@gmail.com [Faculty of Engineering and Surveying, University of Southern Queensland (Australia); Dehghani, Kamran [Department of Mining and Metallurgy, AmirKabir University of Technology, Tehran (Iran, Islamic Republic of)

    2013-06-15

    To investigate the hot deformation behavior of the Ni-42.5Ti-7.5Cu (wt%) alloy, hot compression tests were carried out at the temperatures from 800 °C to 1000 °C and at the strain rates of 0.001 s{sup −1} to 1 s{sup −1}. The results show that the occurrence of dynamic recrystallization (DRX) is the dominate restoration mechanism during the hot deformation of this alloy. There is an increase in peak and steady state stresses with decreasing the deformation temperature and increasing the strain rate. The experimental results were then used to determine the constants of developed constitutive equations. There is a good agreement between the measured and predicted results indicating a high accuracy of developed model. Zener–Hollomon (Z) parameter, calculated based on the developed model, indicates that DRX was postponed when the logarithm of the Zener–Hollomon parameter fell around 33 at strain rate of 0.001 s{sup −1} and temperature of 900 °C. This phenomenon can be regarded as the interactions between solute atoms and mobile dislocations. The established constitutive equations can be used to predict and analyze the hot deformation behavior of Ni-42.5Ti-7.5Cu alloy. - Highlights: • Flow stress behavior of Ni-42.5Ti-7.5Cu studied and modeled for the first time. • The model considered the compensation of both strain and strain rate. • DRX was postponed when logarithm of Z parameter was around 33 at strain rate of 0.001 s{sup −1} and 900 °C. • Ti(NiCu){sub 2} Precipitates, formed via SIP during deformation, postponed DRX.

  14. Evaluating the effects of hydroxyapatite coating on the corrosion behavior of severely deformed 316Ti SS for surgical implants

    Energy Technology Data Exchange (ETDEWEB)

    Mhaede, Mansour, E-mail: mansour.mhaede@yahoo.com [Institute of Materials Science and Engineering, Clausthal University of Engineering, Agicolastr.6, 38678 Clausthal-Zellerfeld (Germany); Faculty of Engineering, Zagazig University, 44519 Zagazig (Egypt); Ahmed, Aymen; Wollmann, Manfred; Wagner, Lothar [Institute of Materials Science and Engineering, Clausthal University of Engineering, Agicolastr.6, 38678 Clausthal-Zellerfeld (Germany)

    2015-05-01

    The present work investigates the effects of severe plastic deformation by cold rolling on the microstructure, the mechanical properties and the corrosion behavior of austenitic stainless steel (SS) 316Ti. Hydroxyapatite coating (HA) was applied on the deformed material to improve their corrosion resistance. The martensitic transformation due to cold rolling was recorded by X-ray diffraction spectra. The effects of cold rolling on the corrosion behavior were studied using potentiodynamic polarization. The electrochemical tests were carried out in Ringer's solution at 37 ± 1 °C. Cold rolling markedly enhanced the mechanical properties while the electrochemical tests referred to a lower corrosion resistance of the deformed material. The best combination of both high strength and good corrosion resistance was achieved after applying hydroxyapatite coating. - Highlights: • Cold rolling markedly increases the hardness of SS 316Ti from 125 to 460 HV10. • Higher deformation degrees lead to lower corrosion resistance. • Application of HA-coating leads to significant improvement of the corrosion resistance.

  15. Deformation Behavior of Nanostructured Ceramic Coatings Deposited by Thermal Plasma Spray

    Institute of Scientific and Technical Information of China (English)

    Xianliang JIANG; Eric Jordan; Leon Shaw; Maurice Gell

    2004-01-01

    Al2O3-13 wt pct TiO2 coating deposited by direct current plasma spray consists of nanostructured region and microlamellae. Bend test shows that the ceramic coating can sustain some deformation without sudden failure. The deformation is achieved through the movement of nano-particles in the nanostructured region under tensile stress.

  16. Effect of Strain Rate on Deformation Behavior of AlCoCrFeNi High-Entropy Alloy by Nanoindentation

    Science.gov (United States)

    Tian, L.; Jiao, Z. M.; Yuan, G. Z.; Ma, S. G.; Wang, Z. H.; Yang, H. J.; Zhang, Y.; Qiao, J. W.

    2016-06-01

    In this study, nanoindentation tests with continuous stiffness measurement technique were measured to investigate the deformation behavior of a high-entropy alloy AlCoCrFeNi under different indentation strain rates at room temperature. Results suggest that the creep behavior exhibits remarkable strain rate dependence. In-situ scanning images showed a conspicuous pileup around the indents, indicating that an extremely localized plastic deformation occurred during the nanoindentation. Under different strain rates, elastic modulus basically remains unchanged, while the hardness decreases with increasing indentation depth due to the indentation size effect. Furthermore, the modulus and hardness of AlCoCrFeNi HEAs are greater than that of the Al x CoCrFeNi ( x = 0.3,0.5) at the strain rate of 0.2 s-1 due to its higher negative enthalpy of mixing related to the atomic binding force, and the solid solution strengthening induced by the lattice distortion, respectively.

  17. Actuation Mechanism of Two-step Reverse Transformation Behavior in TiNi Alloys Deformed at Parent Phase

    Institute of Scientific and Technical Information of China (English)

    HUAILi-min; CUILi-shan; ZHANGLai-bin; ZHENGYan-jun

    2004-01-01

    The actuation mechanism of TiNi shape memory alloy wires, which were deformed at parentphase followed by a cooling process under constant strain constraint, was investigated. The experimental resuhsshow that the two-step reverse martensitic transformation behavior occurs during the heating process, and the tem-perature range of reverse transformation was olwiously widened with the increasing of prestrain,The recovery strainvs temperature curves exhibits an actuation eharaeteristic of linear output recovery strain in a wide temperaturerange.

  18. Deformation behavior after stress-induced martensite transformation in a Ti-50.8 at.% Ni alloy

    Directory of Open Access Journals (Sweden)

    Wang Xiebin

    2015-01-01

    Full Text Available In this study, the deformation behavior of a Ti-50.8 at.% Ni thin wire, which was subjected to different heat treatments, was investigated by means of uniaxial tensile tests. Considerable ductility (tensile elongation >50% and a large variation of the stress-strain relations are observed after different heat treatments, especially in the stage after the stress-induced martensite transformation plateau. A possible explanation for the observed phenomenon is discussed in this work.

  19. Study on the Thermal Fatigue Behavior of Hot Deformed Wear Resistance Cast Iron and Effect of Carbide

    Institute of Scientific and Technical Information of China (English)

    Dong Litao; Liu Rongchang; Li Xingyuan; Chen Xiuhong

    2007-01-01

    The thermal fatigue behavior of wear resistance cast iron with different quantity of deformation has been investigated. The results show that eutectic carbide is the main location and passage for initiation and extension of thermal fatigue cracks, approving that the more serious, the carbide breaks. The higher thermal fatigue resistance of wear resistance cast iron will be and thermal fatigue fracture belongs mainly to brittleness.

  20. Study of the influence of degenerative intervertebral disc changes on the deformation behavior of the cervical spine segment in flexion

    Science.gov (United States)

    Kolmakova, Tatyana V.

    2016-11-01

    The paper describes the model of the cervical spine segment (C3-C4) and the calculation results of the deformation behavior of the segment under degenerative changes of the intervertebral disc. The segment model was built based on the experimental literature data taking into account the presence of the cortical and cancellous bone tissue of vertebral bodies. The calculation results show that degenerative changes of the intervertebral disc cause the immobility of the C3 vertebra at flexion.

  1. Structural properties, deformation behavior and thermal stability of martensitic Ti-Nb alloys

    Energy Technology Data Exchange (ETDEWEB)

    Boenisch, Matthias

    2016-06-10

    Ti-Nb alloys are characterized by a diverse metallurgy which allows obtaining a wide palette of microstructural configurations and physical properties via careful selection of chemical composition, heat treatment and mechanical processing routes. The present work aims to expand the current state of knowledge about martensite forming Ti-Nb alloys by studying 15 binary Ti-c{sub Nb}Nb (9 wt.% ≤ c{sub Nb} ≤ 44.5 wt.%) alloy formulations in terms of their structural and mechanical properties, as well as their thermal stability. The crystal structures of the martensitic phases, α{sup '} and α'', and the influence of the Nb content on the lattice (Bain) strain and on the volume change related to the β → α{sup '}/α'' martensitic transformations are analyzed on the basis of Rietveld-refinements. The magnitude of the shuffle component of the β → α{sup '}/α'' martensitic transformations is quantified in relation to the chemical composition. The largest transformation lattice strains are operative in Nb-lean alloys. Depending on the composition, both a volume dilatation and contraction are encountered and the volume change may influence whether hexagonal martensite α{sup '} or orthorhombic martensite α'' forms from β upon quenching. The mechanical properties and the deformation behavior of martensitic Ti-Nb alloys are studied by complementary methods including monotonic and cyclic uniaxial compression, nanoindentation, microhardness and impulse excitation technique. The results show that the Nb content strongly influences the mechanical properties of martensitic Ti-Nb alloys. The elastic moduli, hardness and strength are minimal in the vicinity of the limiting compositions bounding the interval in which orthorhombic martensite α'' forms by quenching. Uniaxial cyclic compressive testing demonstrates that the elastic properties of strained samples are different than those of unstrained ones

  2. On the deformation mechanisms and electrical behavior of highly stretchable metallic interconnects on elastomer substrates

    Science.gov (United States)

    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.

  3. Microstructural evolution and deformation behavior of twinning-induced plasticity (TWIP) steel during wire drawing

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Joong-Ki [Graduate Institute of Ferrous Technology, POSTECH, Pohang 790-784 (Korea, Republic of); Steel Products Research Group, Technical Research Laboratories, POSCO, Pohang 790-785 (Korea, Republic of); Yi, Il-Cheol [Graduate Institute of Ferrous Technology, POSTECH, Pohang 790-784 (Korea, Republic of); Son, Il-Heon; Yoo, Jang-Yong [Steel Products Research Group, Technical Research Laboratories, POSCO, Pohang 790-785 (Korea, Republic of); Kim, Byoungkoo [Materials Technology Development Team, DHIC, Changwon 642-792 (Korea, Republic of); Zargaran, A. [Graduate Institute of Ferrous Technology, POSTECH, Pohang 790-784 (Korea, Republic of); Kim, Nack J., E-mail: njkim@postech.ac.kr [Graduate Institute of Ferrous Technology, POSTECH, Pohang 790-784 (Korea, Republic of)

    2015-09-17

    The effect of wire drawing on the microstructural evolution and deformation behavior of Fe–Mn–Al–C twinning-induced plasticity (TWIP) steel has been investigated. The inhomogeneities of the stress state, texture, microstructure, and mechanical properties were clarified over the cross section of drawn wire with the aid of numerical simulation, Schmid factor analysis, and electron backscatter diffraction (EBSD) techniques. The analysis of texture in drawn wire shows that a mixture of <111> and <100> fiber texture was developed with strain; however, the distribution of <111> and <100> fibers was inhomogeneous along the radial direction of wire due to uneven strain distribution and different stress state along the radial direction. It has also been shown that the morphology, volume fraction, and variant system of twins as well as twinning rate were dependent on the imposed stress state. The surface area was subjected to larger strain and more complex stress state involving compression, shear, and tension than the center area, resulting in a larger twin volume fraction and more twin variants in the former than in the latter at all the strain levels. While the surface area was saturated with twins at an early stage of drawing, the center area was not saturated with twins even at fracture, implying that the fracture of wire were initiated at the surface area because of the exhaustion of ductility due to twinning. Based on these results, it is suggested that imposing a uniform strain distribution along the radial direction of wire by the control of processing conditions such as die angle and amount of reduction per pass is necessary to increase the drawing limit of TWIP steel.

  4. Deformation behavior of lead zirconate titanate ceramics under uniaxial compression measured by the digital image correlation method

    Science.gov (United States)

    Chen, Di; Carter, Emma; Kamlah, Marc

    2016-09-01

    The deformation behavior of lead zirconate titanate bulk ceramic specimen under uniaxial compression was monitored by the digital image correlation method and the homogeneity of the deformation was discussed. Combined with using a Sawyer-Tower circuit, the depolarization curve was also obtained. Because of the friction at both the top and bottom surfaces of the lead zirconate titanate ceramic specimen, the distribution of deformation under large uniaxial compressive stresses usually shows a barrel shape. By focusing on correspondingly selected regions of interest and calculating the values of strain components there, the barreling behavior was proved. This barreling behavior is due to elastic strains, in the first place, while the remnant strains are less affected by this phenomenon. All these findings are the experimental justifications for the selection of an aspect ratio of 3:1 for our specimens, where only the central cubic region of a specimen represents the desired purely uniaxial stress state. Only from this region, true uniaxial stress-strain results can be obtained to develop constitutive models.

  5. How Deformation Behavior Controls Product Performance After Twin Screw Granulation With High Drug Loads and Crospovidone as Disintegrant.

    Science.gov (United States)

    Meier, Robin; Moll, Klaus-Peter; Krumme, Markus; Kleinebudde, Peter

    2017-01-01

    This study addresses the quantitative influence of 12 different materials (active pharmaceutical ingredients and excipients as surrogate active pharmaceutical ingredients) on the critical quality attributes of twin screw granulated products and subsequently produced tablets. Prestudies demonstrated the significant influence of the chosen model materials (in combination with crospovidone) on the disintegration behavior of the resulting tablets, despite comparable tablet porosities. This study elucidates possible reasons for the varying disintegration behavior by investigating raw material, granule, and tablet properties. An answer could be found in the mechanical properties of the raw materials and the produced granules. Through compressibility studies, the materials could be classified into materials with high compressibility, which deform rather plastically under compression stress, and low compressibility, which display breakages under compression stress. In general, and apart from (pseudo)-polymorphic transformations, brittle materials featured excellent disintegration performance, even at low resulting tablet porosities <8%, whereas plastically deformable materials mostly did not reveal any disintegration. These findings must be considered in the development of simplified formulations with high drug loads, in which the active pharmaceutical ingredient predominantly defines the deformation behavior of the granule.

  6. Quantum equilibria for macroscopic systems

    Energy Technology Data Exchange (ETDEWEB)

    Grib, A [Department of Theoretical Physics and Astronomy, Russian State Pedagogical University, St. Petersburg (Russian Federation); Khrennikov, A [Centre for Mathematical Modelling in Physics and Cognitive Sciences Vaexjoe University (Sweden); Parfionov, G [Department of Mathematics, St. Petersburg State University of Economics and Finances (Russian Federation); Starkov, K [Department of Mathematics, St. Petersburg State University of Economics and Finances (Russian Federation)

    2006-06-30

    Nash equilibria are found for some quantum games with particles with spin-1/2 for which two spin projections on different directions in space are measured. Examples of macroscopic games with the same equilibria are given. Mixed strategies for participants of these games are calculated using probability amplitudes according to the rules of quantum mechanics in spite of the macroscopic nature of the game and absence of Planck's constant. A possible role of quantum logical lattices for the existence of macroscopic quantum equilibria is discussed. Some examples for spin-1 cases are also considered.

  7. X-Ray Tomographic Characterization of the Macroscopic Porosity of Chemical Vapor Infiltration SiC/SiC Composites: Effects on the Elastic Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Gelebart, L.; Chateau, C. [CEA Saclay, SRMA, F-91190 Gif Sur Yvette (France); Chateau, C.; Bornert, M. [Ecole Polytech, LMS, F-91128 Palaiseau (France); Crepin, J. [CDM Mines Paris Paristech, F-91003 Evry (France); Boller, E. [ESRF ID19, F-38043 Grenoble 9 (France)

    2010-07-01

    This paper focuses on the characterization of the macro-porosity, the porosity among the tows, observed in chemical vapor infiltration composites and on its effect on the thermo-mechanical behavior. The experimental characterization of macro-porosity is performed using an X-ray tomography technique. Numerical 3D images are used to describe the distribution of macro-porosity with respect to the position of the plies. It is clearly established that the stacking of the plies has a significant effect on the porosity distribution. As a consequence for the micromechanical modelling, a unique element that contains only one ply is not representative of the porosity distribution and is not sufficient to evaluate the 'effective' mechanical properties; several volume elements (VE), called 'statistical volume elements (SVE)', with at least two plies per VE have to be used in order to account for the variability of the stacking of the plies. Finally, such SVE are directly extracted from the tomographic image and the 'effective' elastic behavior is evaluated from the average of the 'apparent' behavior evaluated on each SVE. In spite of their quite important size, the 'apparent' behaviors evaluated for each SVE exhibit important fluctuations. (authors)

  8. Effects of strain rate on the hot deformation behavior and dynamic recrystallization in China low activation martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yuanyuan [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen, Xizhang, E-mail: kernel.chen@gmail.com [School of Mechanical and Electrical Engineering, Wenzhou University, Wenzhou 325035 (China); Madigan, Bruce [Montana Tech, Butte, MT (United States); Cao, Hongyan [School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Konovalov, Sergey [Center for Collective Use Material Science, Siberian State Industrial University, Novokuznetsk (Russian Federation)

    2016-02-15

    Graphical abstract: - Highlights: • Average grain sizes of 1.8 μm are observed at strain rate of 10 s{sup −1}. • Peak stress value increased, but strain decreased with increasing of strain rate. • A catenuliform recrystallized occurred at a strain rate of 5 s{sup −1}. • DRX effect improved with increasing of deformation amounts. - Abstract: To investigate the effects of strain rate on dynamic recrystallization (DRX) behavior on China low activation martensitic steel, hot uniaxial compression tests with strain rates ranging from 0.1 s{sup −1} to 10 s{sup −1} and deformations amounts of 40% and 70% where conducted. The true stress–true strain curves were analyzed for the occurrence of DRX under the different strain rates and compressive deformation amounts. The steel microstructures were examined and linked to the observed stress-strain diagrams to study DRX. Results show that DRX was responsible for refining the grain structure over a wide range of strain rates under 70% deformation. However, significant DRX occurred only at the relatively low strain rate of 0.1 s{sup −1} under 40% deformation. The original elongated microstructure of the rolled plate from which the specimens were taken was replaced by dynamic recrystallization grains. At 70% deformation, the average grain size was 4.2 μm at a strain rate of 0.1 s{sup −1}, 2.5 μm at a strain rate of 5 s{sup −1}, 1.8 μm at a strain rate of 10 s{sup −1}. In conclusion, with increasing strain rate, the recrystallized grain size decreased and the peak stress increased.

  9. Deformation behaviors of 21-6-9 stainless steel tube numerical control bending under different friction conditions

    Institute of Scientific and Technical Information of China (English)

    方军; 鲁世强; 王克鲁; 姚正军

    2015-01-01

    For contact dominated numerical control (NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional (3D) elastic-plastic finite element (FE) model of NC bending process was established under ABAQUS/Explicit platform, and its reliability was validated by the experiment. Then, numerical study on bending deformation behaviors under different frictions between tube and various dies was explored from multiple aspects such as wrinkling, wall thickness change and cross section deformation. The results show that the large friction of wiper die−tube reduces the wrinkling wave ratioη and cross section deformation degreeΔD and increases the wall thinning degreeΔt. The large friction of mandrel−tube causes largeη,Δt andΔD, and the onset of wrinkling near clamp die. The large friction of pressure die−tube reducesΔt andΔD, and the friction on this interface has little effect onη. The large friction of bending die−tube reducesη andΔD, and the friction on this interface has little effect onΔt. The reasonable friction coefficients on wiper die−tube, mandrel−tube, pressure die−tube and bending die−tube of 21-6-9 (0Cr21Ni6Mn9N) stainless steel tube in NC bending are 0.05−0.15, 0.05−0.15, 0.25−0.35 and 0.25−0.35, respectively. The results can provide a guideline for applying the friction conditions to establish the robust bending environment for stable and precise bending deformation of tube bending.

  10. Fingerprinting Molecular Relaxation in Deformed Polymers

    Science.gov (United States)

    Wang, Zhe; Lam, Christopher N.; Chen, Wei-Ren; Wang, Weiyu; Liu, Jianning; Liu, Yun; Porcar, Lionel; Stanley, Christopher B.; Zhao, Zhichen; Hong, Kunlun; Wang, Yangyang

    2017-07-01

    The flow and deformation of macromolecules is ubiquitous in nature and industry, and an understanding of this phenomenon at both macroscopic and microscopic length scales is of fundamental and practical importance. Here, we present the formulation of a general mathematical framework, which could be used to extract, from scattering experiments, the molecular relaxation of deformed polymers. By combining and modestly extending several key conceptual ingredients in the literature, we show how the anisotropic single-chain structure factor can be decomposed by spherical harmonics and experimentally reconstructed from its cross sections on the scattering planes. The resulting wave-number-dependent expansion coefficients constitute a characteristic fingerprint of the macromolecular deformation, permitting detailed examinations of polymer dynamics at the microscopic level. We apply this approach to survey a long-standing problem in polymer physics regarding the molecular relaxation in entangled polymers after a large step deformation. The classical tube theory of Doi and Edwards predicts a fast chain retraction process immediately after the deformation, followed by a slow orientation relaxation through the reptation mechanism. This chain retraction hypothesis, which is the keystone of the tube theory for macromolecular flow and deformation, is critically examined by analyzing the fine features of the two-dimensional anisotropic spectra from small-angle neutron scattering by entangled polystyrenes. We show that the unique scattering patterns associated with the chain retraction mechanism are not experimentally observed. This result calls for a fundamental revision of the current theoretical picture for nonlinear rheological behavior of entangled polymeric liquids.

  11. Warm deformation behavior of hot-rolled AZ31 Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Yin, D.L. [Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)]. E-mail: d_l_yin2000@hit.edu.cn; Zhang, K.F. [Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); Wang, G.F. [Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China); Han, W.B. [Key Laboratory of Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)

    2005-02-15

    Uniaxial tensile test was employed to evaluate the warm deformation properties of hot-rolled AZ31 Mg alloy at a temperature range of 50-200 deg. C and a strain rate range of 1.4 x 10{sup -3} s{sup -1}-1.4 x 10{sup -1} s{sup -1}. The dynamic recrystallization (DRX) and twinning during the warm deformation were observed by optical microscopy (OM) and transmission electronic microscopy (TEM). It is shown that twinning characterized by a compound mode with differently oriented twins intersecting each other is the dominant deformation mechanism at low temperatures and initial deformation stage. The distortion energy accumulated by twinning is the reason for the occurrence of DRX.

  12. Episodic behavior of Gondwanide deformation in eastern Australia: Insights from the Gympie Terrane

    Science.gov (United States)

    Hoy, Derek; Rosenbaum, Gideon

    2017-08-01

    The mechanisms that drove Permian-Triassic orogenesis in Australia and throughout the Cordilleran-type Gondwanan margin is a subject of debate. Here we present field-based results on the structural evolution of the Gympie Terrane (eastern Australia), with the aim of evaluating its possible role in triggering widespread orogenesis. We document several deformation events (D1-D3) in the Gympie Terrane and show that the earliest deformation, D1, occurred only during the final pulse of orogenesis (235-230 Ma) within the broader Gondwanide Orogeny. In addition, we found no evidence for a crustal suture, suggesting that terrane accretion was not the main mechanism behind deformation. Rather, the similar spatiotemporal evolution of Permian-Triassic orogenic belts in Australia, Antarctica, South Africa, and South America suggest that the Gondwanide Orogeny was more likely linked to large-scale tectonic processes such as plate reorganization. In the context of previous work, our results highlight a number of spatial and temporal variations in pulses of deformation in eastern Australia, suggesting that shorter cycles of deformation occurred at a regional scale within the broader episode of the Gondwanide Orogeny. Similarly to the Cenozoic evolution of the central and southern Andes, we suggest that plate coupling and orogenic cycles in the Late Paleozoic to Early Mesozoic Gondwanide Orogeny have resulted from the superposition of mechanisms acting at a range of scales, perhaps contributing to the observed variations in the intensity, timing, and duration of deformation phases within the orogenic belt.

  13. INVESTIGATION INTO HOT DEFORMATION BEHAVIOR OF SPRAY FORMED SUPERALLOY GH742

    Institute of Scientific and Technical Information of China (English)

    Z.Li; G.Q.Zhang; Z.H.Zhang; S.F.Tian

    2004-01-01

    In order to evaluate the deformation characteristics of spray formed superalloy GH742 and determine the appropriate forging procedure of the alloy on this basis,the influence of deformation temperature and strain rate on the ductility of spray formed GH742 was investigated by using the Gleeble-3500 thermal-mechanical testing machine.It is shown that the forgeability of spray formed GH742 is better than conventional GH742 by ingot metallurgy because of refined grain structure and enhanced chemical homogeneity of spray formed GH742.In the temperature range of 1020 to 1100℃,the ductility of spray formed GH742 is dependent on the deformation temperature and is increased linearly in proportion to the increment of deformation temperature,which is more than 40% at 1020℃ and more than 60% at the temperature between 1100 and 1140℃.Furthermore,the results indicate the flow stress is affected considerably by the deformation temperature and strain rate.In the temperature range of 1020 to 1140℃,the maximum flow stress of spray formed GH742 increases with the increment of strain rate and decreases with the increment of the deformation temperature.

  14. Severe plastic deformation using friction stir processing, and the characterization of microstructure and mechanical behavior using neutron diffraction

    Science.gov (United States)

    Woo, Wanchuck

    Friction-stir welding (FSW) is a solid-state joining process, which utilizes a cylindrical rotating tool consisting of a concentric threaded tool pin and tool shoulder. The strong metallurgical bonding during the FSW is accomplished through: (1) the severe plastic deformation caused by the rotation of the tool pin that plunges into the material and travels along the joining line; and (2) the frictional heat generated mainly from the pressing tool shoulder. Recently, a number of variations of the FSW have been applied to modify the microstructure, for example, grain refinements and homogenization of precipitate particles, namely friction-stir processing (FSP). Applications of the FSP/FSW are widespread for the transportation industries. The microstructure and mechanical behavior of light-weight materials subjected to the FSW/FSP are being studied extensively. However, separating the effect of the frictional heat and severe plastic deformation on the residual stress and texture has been a standing problem for the fundamental understanding of FSW/FSP. The fundamental issues are: (i) the heat- and plastic-deformation-induced internal stresses that may be detrimental to the integrity and performance of components; (ii) the frictional heating that causes a microstructural softening due to the dissolution or growth of the precipitates in precipitation-hardenable Al alloys during the process; and (iii) the crystallographic texture can be significantly altered from the original texture, which could affect the physical and mechanical properties. The understanding of the influences of the de-convoluted sources (e.g. frictional heat, severe plastic deformation, or their combination) on the residual stress, microstructural softening, and texture variations during FSW can be used for a physicsvi based optimization of the processing parameters and new tool designs. Furthermore, the analyses and characterization of the natural aging behavior and the aging kinetics can be

  15. VISCOELASTIC BEHAVIOR OF THE NON-HOOKE DEFORMATION BEFORE YIELDING IN UNIAXIAL DRAWING OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE)

    Institute of Scientific and Technical Information of China (English)

    Zhen-hua Yuan; De-yan Shen; Ren-yuan Qian

    2001-01-01

    Viscoelastic behavior of the non-Hooke deformation of amorphous PET film before yield was investigated in the temperature region 74-80.5 ℃ around the glass transition temperature. The film specimen was drawn to yield point followed by unloading to zero stress, then the residual deformation was held constant, while the subsequent evolution of the stress was recorded. An induction period was found in the course of stress evolution followed by a stress step-increase. The induction period decreases with increasing drawing temperature with an activation energy of 1.10 MJ/mol @ K, which is attributed to the time needed for the relaxation of rubbery deformation through cooperative internal rotations. At temperatures lower than 74℃, there is no stress increase or the induction period becomes too long to be observed. Thus the nature of anelasticity in the non-Hooke region before yielding is attributed to stress induced rubbery deformation. The experimental results are interpreted in terms of Perez' rheological model of a series connected Hooke spring and a Voigt element consisting of a parallel connected elastic spring and a dashpot.``

  16. Influences of silicon on the work hardening behavior and hot deformation behavior of Fe–25 wt%Mn–(Si, Al) TWIP steel

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dejun, E-mail: lidejun352@163.com [CNPC Tubular Goods Research Institute, Xi’an 710077 (China); The Key Lab for Petroleum Tubular Goods Engineering, CNPC, Xi’an 710077 (China); Feng, Yaorong; Song, Shengyin; Liu, Qiang; Bai, Qiang [CNPC Tubular Goods Research Institute, Xi’an 710077 (China); The Key Lab for Petroleum Tubular Goods Engineering, CNPC, Xi’an 710077 (China); Ren, Fengzhang [School of Material Science and Engineering, Henan University of Science and Technology, Luoyang 471023 (China); Shangguan, Fengshou [CNPC Tubular Goods Research Institute, Xi’an 710077 (China); The Key Lab for Petroleum Tubular Goods Engineering, CNPC, Xi’an 710077 (China)

    2015-01-05

    Highlights: • Influence of Si on work hardening behavior of Fe–25 wt%Mn TWIP steel was investigated. • Influence of Si on hot deformation behavior of Fe–25 wt%Mn TWIP steel was studied. • Si blocks dislocation glide and favors mechanical twinning in Fe–25 wt%Mn TWIP steel. • The addition of Si increases the hot deformation activation energy of Fe–25 wt%Mn TWIP steel. • The addition of Si retards the nucleation and growth of DRX grains of Fe–25 wt%Mn TWIP steel. - Abstract: The influence of silicon on mechanical properties and hot deformation behavior of austenitic Fe–25 wt%Mn TWIP steel was investigated by means of the comparison research between 25Mn3Al and 25Mn3Si3Al steel. The results show that the 25Mn3Si3Al steel has higher yield strength and higher hardness than that of 25Mn3Al steel because of the solution strengthening caused by Si atoms and possesses higher uniform deformation ability and tensile strength than that of 25Mn3Al steel due to the higher work hardening ability of 25Mn3Si3Al steel. 25Mn3Si3Al steel presents a clear four-stage curve of work hardening rate in course of cold compression. Quite the opposite, the 25Mn3Al steel presents a monotonic decline curve of work hardening rate. The difference of the work hardening behavior between 25Mn3Al and 25Mn3Si3Al steel can be attributed to the decline of stacking fault energy (SFE) caused by the addition of 3 wt% Si. The dislocation glide plays an important role in the plastic deformation of 25Mn3Al steel even though the mechanical twinning is still one of the main deformation mechanisms. The 3 wt% Si added into the 25Mn3Al steel blocks the dislocation glide and promotes the mechanical twinning, and then the dislocation glide characteristics cannot be observed in cold deformed microstructure of 25Mn3Si3Al steel. The hot compression tests reveal that the hot deformation resistance of the 25Mn3Si3Al steel is significantly higher than that of the 25Mn3Al steel due to the solid

  17. Constitutive Cyclic Deformation Behavior in Single-crystal and Directionally Solidified SSME High-pressure Fuel Turbopump Airfoil Materials

    Science.gov (United States)

    Milligan, W. W.; Huron, E. S.; Antolovich, S. D.

    1985-01-01

    The major goal of the project is to correlate mechanical properties with microstructural deformation behavior and to develop models for constitutive response under a variety of monotonic and cyclic loading cycles, temperatures, strain levels, strain rates, and environments. Two alloys are being studied as candidate SSME turbine blade materials. The first is PWA 1480, which is a single-crystal alloy whose nominal composition is reported. The second alloy being studied is D.S. Mar-M 246 + Hf. This is a directionally solidified material, and its nominal composition is also reported. The major areas of interest for the two materials will be slightly different. The single-crystal alloy lends itself well to fundamental deformation studies, since resolved shear stresses on slip planes are all known and only one grain is present. The D.S. material presents an excellent opportunity to study the effects of slightly misaligned grains on deformation behavior. The two materials will be studied by using approximately the same test matrix, so a good degree of direct comparison will also be possible.

  18. EFFECTS OF HIGH-DENSITY CURRENT PULSES ON WORKHARDENING BEHAVIORS OF AUSTENITE STAINLESS STEELIN WIRE-DRAWING DEFORMATION

    Institute of Scientific and Technical Information of China (English)

    K.F. Yao; P. Yu; J. Wang; W. Fang; M.X. Zheng

    2001-01-01

    The influence of high-density palsing current on the work-hardening behavior of H0Cr17Ni6Mn3 and 1Cr18Ni9 stainless steels in wire-drawing deformation processes has been studied. It was found that the drawing stress and the work-hardening rate of wires were significantly reduced by applying current pulses in drawing process. The work-hardening behavior of the multi-courses drawing deformation can be well described by Hollomon formula σ = kεn. With the application of current pulses in drawing deformation, the work-hardening exponents of H0Cr17Ni6Mn3 steel wires and 1Cr18Ni9 stainless steel wires were reduced by 33% and 45%, respectively, and their work-hardening coefficients were reduced by 41% and 47%, respectively. It was also found that the work-hardening coefficient of wires was reduced with the increment of the frequency of current pulses, while the work-hardening exponents of both steels were insensitive to the pulsing frequency.``

  19. Microstructure evolution and fracture behavior in superplastic deformation of hot-rolled AZ31 Mg alloy sheet

    Energy Technology Data Exchange (ETDEWEB)

    Yin, D.L.; Zhang, K.F.; Wang, G.F. [School of Material Science and Technology, Harbin Inst. of Tech. (China)

    2005-07-01

    Fine-grained AZ31 magnesium alloy sheets were prepared through hot rolling process. The superplastic properties of hot-rolled AZ31 Mg alloy was examined by uniaxial tensile tests at a temperature range 250{proportional_to}450 C and strain rate range 0.7 x 10{sup -3}{proportional_to}1.4 x 10{sup -1} s{sup -1}. Optical and scanning electronic microscope (SEM) were used to observe the microstructure evolution and fracture behavior in superplastic deformation of AZ31 Mg alloy and the values of deformation activation energy at various temperatures were calculated. It is demonstrated that, the hot-rolled AZ31 alloy begins to exhibit superplasticity from 300 C and a maximum elongation of 362.5% is obtained at 400 C and 0.7 x 10{sup -3} s{sup -1}. In the temperature range 300{proportional_to}400 C, the dominant superplastic deformation mechanism is grain boundary sliding (GBS) controlled by grain boundary diffusion and the influence of temperature on the fracture behavior of AZ31 Mg alloy is characterized by the change from dimple-aggregating type to intercrystalline one. (orig.)

  20. Hot Deformation Behavior of a Differential Pressure Casting Mg-8Gd-4Y-Nd-Zr Alloy

    Science.gov (United States)

    Tang, Changping; Liu, Wenhui; Chen, Yuqiang; Liu, Xiao; Deng, Yunlai

    2016-11-01

    To fabricate components with high performance, the compression behavior and microstructure evolution of a differential pressure casting Mg-8Gd-4Y-Nd-Zr alloy were investigated. The cylindrical samples were compressed at temperatures ranging from 350 °C to 525 °C and strain rates ranging from 0.001 s-1 to 2 s-1. For the compression at 350 °C, dynamic precipitation occurs and consumes much of the solutes in the matrix, which should be avoided. The recrystallized grain size (d) decreases when the proposed deformation parameter (Z) increases, and the resulting Z-d relationship is established. Finally, a superior deformation process of 500 °C/0.01 s-1 is determined based on the experimental results. Moreover, a plate with an ultimate tensile strength of 413 MPa was fabricated.

  1. Hot Deformation Behavior of a Differential Pressure Casting Mg-8Gd-4Y-Nd-Zr Alloy

    Science.gov (United States)

    Tang, Changping; Liu, Wenhui; Chen, Yuqiang; Liu, Xiao; Deng, Yunlai

    2017-01-01

    To fabricate components with high performance, the compression behavior and microstructure evolution of a differential pressure casting Mg-8Gd-4Y-Nd-Zr alloy were investigated. The cylindrical samples were compressed at temperatures ranging from 350 °C to 525 °C and strain rates ranging from 0.001 s-1 to 2 s-1. For the compression at 350 °C, dynamic precipitation occurs and consumes much of the solutes in the matrix, which should be avoided. The recrystallized grain size (d) decreases when the proposed deformation parameter (Z) increases, and the resulting Z-d relationship is established. Finally, a superior deformation process of 500 °C/0.01 s-1 is determined based on the experimental results. Moreover, a plate with an ultimate tensile strength of 413 MPa was fabricated.

  2. Effect of Temperature on the Deformation Behavior of B2 Austenite in a Polycrystalline Ni49.9Ti50.1 (at.Percent) Shape Memory Alloy

    Science.gov (United States)

    Garg, A.; Benafan, O.; Noebe, R. D.; Padula, S. A., II; Clausen, B.; Vogel, S.; Vaidyanathan, R.

    2013-01-01

    Superelasticity in austenitic B2-NiTi is of great technical interest and has been studied in the past by several researchers [1]. However, investigation of temperature dependent deformation in B2-NiTi is equally important since competing mechanisms of stress-induced martensite (SIM), retained martensite, plastic and deformation twinning can lead to unusual mechanical behaviors. Identification of the role of various mechanisms contributing to the overall deformation response of B2-NiTi is imperative to understanding and maturing SMA-enabled technologies. Thus, the objective of this work was to study the deformation of polycrystalline Ni49.9Ti50.1 (at. %) above A(sub f) (105 C) in the B2 state at temperatures between 165-440 C, and generate a B2 deformation map showing active deformation mechanisms in different temperature-stress regimes.

  3. Yielding and deformation behavior of the single crystal superalloy PWA 1480

    Science.gov (United States)

    Milligan, Walter W.; Antolovich, Stephen D.

    1987-01-01

    Interrupted tensile tests were conducted to fixed plastic strain levels in 100 ordered single crystals of the nickel based superalloy PWA 1480. Testing was done in the range of 20 to 1093 C, at strain rate of 0.5 and 50 percent/min. The yield strength was constant from 20 to 760 C, above which the strength dropped rapidly and became a strong function of strain rate. The high temperature data were represented very well by an Arrhenius type equation, which resulted in three distinct temperature regimes. The deformation substructures were grouped in the same three regimes, indicating that there was a fundamental relationship between the deformation mechanisms and activation energies. Models of the yielding process were considered, and it was found that no currently available model was fully applicable to this alloy. It was also demonstrated that the initial deformation mechanism (during yielding) was frequently different from that which would be inferred by examining specimens which were tested to failure.

  4. Influence of static tensile testing on the deformation behavior of Al-4% Cu alloy containing micro- and nanoparticles

    Science.gov (United States)

    Khrustalyov, Anton; Vorozhtov, Sergey; Kulkov, Sergey

    2016-11-01

    At present, aluminum alloys reinforced with nonmetallic particles are of great interest in various fields of science and technology due to their high specific strength, hardness, wear resistance, and other properties. At the same time there is a great interest in the study of processes occurring during plastic deformation of such materials under static tensile loading. Plastic flow of metals occurs through the creation and movement of linear defects (dislocations), in which there is a phenomenon of discontinuous yielding. An introduction of particles into aluminum alloy promotes a considerable increase of stiffness and specific strength of alloys, and the study of the deformation behavior of such alloys is of great interest. The objective of this research is to analyze mechanical properties and the deformation behavior of aluminum alloy with the identification of mechanisms of plastic deformation when introducing solid nonmetallic micro- and nanoparticles into the soft aluminum matrix. An analysis of the microstructure of the obtained alloys shows that the introduction of particles (Al2O3, TiB2, TiC) leads to a reduction of the alloy grain size from 350 to 170 µm while residual porosity does not exceed 2%. Tensile tests performed show that the change in the type and quantity of particles also changes characteristics of discontinuous yielding, thus resulting in an increase of yield strength (from 18 to 40 MPa), reduction of ductility (from 15 to 2%), and moreover a significant increase of tensile strength (from 77 to 130 MPa), as compared to the initial Al-4 wt % Cu alloy.

  5. Thermal behavior of Nickel deformed to ultra-high strain by high pressure torsion

    DEFF Research Database (Denmark)

    Zhang, Hongwang; Huang, Xiaoxu; Pippan, Richard

    2012-01-01

    Polycrystalline Ni (99.5 %) has been deformed to an ultra-high strain of εvM=100 (εvM, von Mises strain) by high pressure torsion (HPT) at room temperature. The deformed sample is nanostructured with an average boundary spacing of 90 nm, a high density of dislocations of >1015m-2 and a large....... The isochronal annealing leads to a hardness drop in three stages: a relatively small decrease at low temperatures (recovery) followed by a rapid decrease at intermediate temperatures (discontinuous recrystallization) and a slow decrease at high temperatures (grain growth). Due to the presence of a small amount...

  6. Effect of Incomplete Thermal Cycle on Transformation Behavior of Deformed TiNi Thin Film

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Compared with the undeformed TiNi film, the martensite-austenite transformation (M-A) of the deformed one is elevated to a higher temperature on the first heating, but it nearly returns back to the original temperature on the second heating. An incomplete M-A transformation of the deformed TiNi film on the first heating divides the total martensite population into the self-accommodating martensite M2 and the oriented martensite M1. Thus, two transformations corresponding to M1-A and M2-A transition occur on the second heating. However, the forward transformation is not affected by the incomplete thermal cycle.

  7. Effect of Initial Backfill Temperature on the Deformation Behavior of Early Age Cemented Paste Backfill That Contains Sodium Silicate

    Directory of Open Access Journals (Sweden)

    Aixiang Wu

    2016-01-01

    Full Text Available Enhancing the knowledge on the deformation behavior of cemented paste backfill (CPB in terms of stress-strain relations and modulus of elasticity is significant for economic and safety reasons. In this paper, the effect of the initial backfill temperature on the CPB’s stress-strain behavior and modulus of elasticity is investigated. Results show that the stress-strain relationship and the modulus of elasticity behavior of CPB are significantly affected by the curing time and initial temperature of CPB. Additionally, the relationship between the modulus of elasticity and unconfined compressive strength (UCS and the degree of hydration was evaluated and discussed. The increase of UCS and hydration degree leads to an increase in the modulus of elasticity, which is not significantly affected by the initial temperature.

  8. Crystallographic Behavior of Iron Oxide Minerals in the Deformed Iron Formation of Quadrilátero Ferrífero

    Science.gov (United States)

    Duarte Lisboa, Filipe Augusto; Lagoeiro, Leonardo; Martins Graça, Leonardo; Ávila, Carlos Fernando; Ferreira Barbosa, Paola

    2016-04-01

    The Quadrilátero Ferrífero (QF) which is located in Brazil represents a mineral province of great importance for hosting Banded Iron Formation deposits (BIFs). The Alegria mine which belongs to Vale Company is located in the east part of Quadrilátero Ferrífero and it explores iron ore from a region of great structural complexity. A deformed BIF sample that presents a micro-fold on quartz and hematite bands was analyzed through Electron Backscatter Diffraction technique (EBSD) in order to relate the crystallographic orientations with the microstructures along the micro-fold envelop. For the sample orientation the Z-axis is taken parallel to the fold limb, Y-axis is perpendicular to the fold hinge and X-axis perpendicular to the YZ plane. In the limbs hematite grains are mostly stretched whereas at the hinge grains tend to be somewhat equant. On the other hand, quartz grain shapes are invariable along the fold, with a few exceptions in the hinge where grains are slightly elongated. Grains of hematite present a strong c-axis ({0001}) preferred orientation forming a subtle girdle somewhat parallel to the XY plane of the strain ellipsoid determined macroscopically (XY being the foliation plane), and a strong () crystallographic fabric approximately parallel to the Z-axis. Similarly, the poles to the prismatic planes ({m} or {10bar10}) also have a stronger crystallographic fabric parallel to the Z axis. It seems that there are two crossing planes for the orientation of and {m} with the two maxima at the intersection of the two planes. Typical hematite crystallographic fabrics are somewhat distinct, since {c} axis commonly forms a very strong fiber texture parallel to the pole of the foliation. Most studies regard such crystallographic texture as evidence for high activity of {c} slip. The {c} girdles observed here are common for mica grains under rigid body rotation in constriction strain, which mechanism is commonly observed in the hematite grains of the sample. The

  9. Stereodynamics: From elementary processes to macroscopic chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kasai, Toshio [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Graduate School of Science, Department of Chemistry, Osaka University, Toyonaka, 560-0043 Osaka (Japan); Che, Dock-Chil [Graduate School of Science, Department of Chemistry, Osaka University, Toyonaka, 560-0043 Osaka (Japan); Tsai, Po-Yu [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Department of Chemistry, National Chung Hsing University, Taichung 402, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Lin, King-Chuen [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan (China); Palazzetti, Federico [Scuola Normale Superiore, Pisa (Italy); Dipartimento di Chimica Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Aquilanti, Vincenzo [Dipartimento di Chimica Biologia e Biotecnologie, Università di Perugia, 06123 Perugia (Italy); Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, Roma (Italy); Instituto de Fisica, Universidade Federal da Bahia, Salvador (Brazil)

    2015-12-31

    This paper aims at discussing new facets on stereodynamical behaviors in chemical reactions, i.e. the effects of molecular orientation and alignment on reactive processes. Further topics on macroscopic processes involving deviations from Arrhenius behavior in the temperature dependence of chemical reactions and chirality effects in collisions are also discussed.

  10. Hydrostatic and shear behavior of frictionless granular assemblies under different deformation conditions

    NARCIS (Netherlands)

    Imole, Olukayode Isaiah; Kumar, Nishant; Magnanimo, Vanessa; Luding, Stefan

    2013-01-01

    Stress- and structure-anisotropy (bulk) responses to various deformation modes are studied for dense packings of linearly elastic, frictionless, polydisperse spheres in the (periodic) triaxial box element test configuration. The major goal is to formulate a guideline for the procedure of how to cali

  11. Influence of thermo hydrogen treatment on hot deformation behavior of Ti600 alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Jing-wei; DING Hua; WANG Yao-qi; HOU Hong-liang

    2009-01-01

    Hot compressive deformation of Ti600 alloy after thermo hydrogen treatment (THT) was carried out within hydrogen content range of 0-0.5%, temperature range of 760-920 ℃ and strain rate range of 0.01-10 s-1. The flow stress of Ti600 alloy after THT was obtained under hot deformation condition, and the influence of hydrogen on work-hardening rate (S*), strain energy density (U*), and deformation activation energy (Q) was analysed. The results show that the flow stress of Ti600 alloy decreases remarkably with the increase of hydrogen when the hydrogen content is less than 0.3%. Both S* and U* decrease with the increase of hydrogen when the hydrogen content is less than 0.3%, and when the hydrogen content is more than 0.3%, S* and U* increase with hydrogen addition. The value of Q decreases with the increase of strain at the same hydrogen content. The addition of small quantity of hydrogen leads to an increase of Q at small strain values, and when the strain reaches 0.6, the value of Q decreases gradually with the increase of hydrogen. When the hydrogen content is within the range of 0.1%-0.3%, the flow stress of Ti600 alloy is decreased when being deformed at the temperature range of 760-920 ℃.

  12. Hydrostatic and shear behavior of frictionless granular assemblies under different deformation conditions

    NARCIS (Netherlands)

    Imole, O.I.; Kumar, N.; Magnanimo, V.; Luding, S.

    2013-01-01

    Stress- and structure-anisotropy (bulk) responses to various deformation modes are studied for dense packings of linearly elastic, frictionless, polydisperse spheres in the (periodic) triaxial box element test configuration. The major goal is to formulate a guideline for the procedure of how to cali

  13. Mechanical Properties and Fracture Behavior of Cu-Co-Be Alloy after Plastic Deformation and Heat Treatment

    Institute of Scientific and Technical Information of China (English)

    Yan-jun ZHOU; Ke-xing SONG; Jian-dong XING; Zhou LI; Xiu-hua GUO

    2016-01-01

    Mechanical properties and fracture behavior of Cu-0.84Co-0.23Be alloy after plastic deformation and heat treatment were comparatively investigated.Severe plastic deformation by hot extrusion and cold drawing was adopted to induce large plastic strain of Cu-0.84Co-0.23Be alloy.The tensile strength and elongation are up to 476.6 MPa and 1 8%,respectively.The fractured surface consists of deep dimples and micro-voids.Due to the formation of su-persaturated solid solution on the Cu matrix by solution treatment at 950 ℃ for 1 h,the tensile strength decreased to 271.9 MPa,while the elongation increased to 42%.The fracture morphology is parabolic dimple.Furthermore,the tensile strength increased significantly to 580.2 MPa after aging at 480 ℃ for 4 h.During the aging process,a large number of precipitates formed and distributed on the Cu matrix.The fracture feature of aged specimens with low elongation (4.6%)exhibits an obvious brittle intergranular fracture.It is confirmed that the mechanical properties and fracture behavior are dominated by the microstructure characteristics of Cu-0.84Co-0.23Be alloy after plastic de-formation and heat treatment.In addition,the fracture behavior at 450 ℃ of aged Cu-0.84Co-0.23Be alloy was also studied.The tensile strength and elongation are 383.6 MPa and 11.2%,respectively.The fractured morphologies are mainly candy-shaped with partial parabolic dimples and equiaxed dimples.The fracture mode is multi-mixed mechanism that brittle intergranular fracture plays a dominant role and ductile fracture is secondary.

  14. Macroscopic-microscopic mass models

    CERN Document Server

    Nix, J R; Nix, J Rayford; Moller, Peter

    1995-01-01

    We discuss recent developments in macroscopic-microscopic mass models, including the 1992 finite-range droplet model, the 1992 extended-Thomas-Fermi Strutinsky-integral model, and the 1994 Thomas-Fermi model, with particular emphasis on how well they extrapolate to new regions of nuclei. We also address what recent developments in macroscopic-microscopic mass models are teaching us about such physically relevant issues as the nuclear curvature energy, a new congruence energy arising from a greater-than-average overlap of neutron and proton wave functions, the nuclear incompressibility coefficient, and the Coulomb redistribution energy arising from a central density depression. We conclude with a brief discussion of the recently discovered rock of metastable superheavy nuclei near 272:110 that had been correctly predicted by macroscopic-microscopic models, along with a possible new tack for reaching an island near 290:110 beyond our present horizon.

  15. Effect of r-value and texture on plastic deformation and necking behavior in interstitial-free steel sheets

    Science.gov (United States)

    Oh, Gyu-Jin; Lee, Kye-Man; Huh, Moo-Young; Park, Jin Eon; Park, Soo Ho; Engler, Olaf

    2017-01-01

    Three initial tensile specimens having different textures and, in consequence, different r-values were cut from a sheet of an interstitial-free steel. Using these specimens, the effect of r-value and texture on plastic deformation and the necking behavior were studied by tackling the strain state and texture during tensile tests. A reduced decrease in work hardening rate of tensile specimens with higher r-values led to a slower onset of diffuse necking which offers an increased uniform elongation. A slower reduction in thickness of specimens with a higher r-value provided a favorable resistance against onset of failure by localized necking.

  16. Computational analysis of linear friction welding process and micromechanical modeling of deformation behavior for medium carbon steel

    Institute of Scientific and Technical Information of China (English)

    杨夏炜; 李文亚; 马铁军

    2015-01-01

    Finite element simulation of linear friction welding (LFW) medium carbon steel was carried out using the ABAQUS software. A two-dimensional (2D) coupled thermo-mechanical model was established. First, the temperature fields of medium carbon steel during LFW process were investigated. And then, the Mises stress and the 1st, 2nd and 3rd principal stresses fields’ evolution of the steel during LFW process were studied. The deformation behavior of LFW carbon steel was analyzed by using micromechanics model based on ABAQUS with Python code. The Lode parameter was expressed using the Mohr stress circle and it was investigated in detail.

  17. Microstructure Evolution and Mechanical Behavior of Ultrafine Ti-6Al-4V During Low Temperature Superplastic Deformation (Postprint)

    Science.gov (United States)

    2016-09-13

    alloys , Russ. J. Non- Ferrous Met. 56 (2016) 437e441. [40] B.B. Straumal, X. Sauvage, B. Baretzky, A.A. Mazilkin, R.Z. Valiev, Grain boundary films in...dynamic coarsening response and plastic-flow behavior of the alloy with a mean size of α (sub)grains and β particles of 0.1–0.4 μm were determined via a...Very limited cavitation was observed in the specimens after superplastic deformation under optimal conditions. 15. SUBJECT TERMS Titanium alloy ; Low

  18. Indentation-Induced Mechanical Deformation Behaviors of AlN Thin Films Deposited on c-Plane Sapphire

    Directory of Open Access Journals (Sweden)

    Sheng-Rui Jian

    2012-01-01

    Full Text Available The mechanical properties and deformation behaviors of AlN thin films deposited on c-plane sapphire substrates by helicon sputtering method were determined using the Berkovich nanoindentation and cross-sectional transmission electron microscopy (XTEM. The load-displacement curves show the “pop-ins” phenomena during nanoindentation loading, indicative of the formation of slip bands caused by the propagation of dislocations. No evidence of nanoindentation-induced phase transformation or cracking patterns was observed up to the maximum load of 80 mN, from either XTEM or atomic force microscopy (AFM of the mechanically deformed regions. Instead, XTEM revealed that the primary deformation mechanism in AlN thin films is via propagation of dislocations on both basal and pyramidal planes. Furthermore, the hardness and Young’s modulus of AlN thin films estimated using the continuous contact stiffness measurements (CSMs mode provided with the nanoindenter are 16.2 GPa and 243.5 GPa, respectively.

  19. On the intergranular fracture behavior of high-temperature plastic deformation of 1420 Al-Li alloy

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The tensile deformation hot simulation test of as-cast 1420 Al-Li alloy was performed on Gleeble-1500 Thermal Simulator in the deformation temperature range from 350 to 450 ℃, and the strain rate range from 0.01 to 10.0 s-1.The tensile fracture behavior of the 1420 Al-Li alloy at high temperature was studied experimently. The results show that the tensile fracture mode of the 1420 Al-Li alloy at high temperature is changed from typical transgranular ductile fracture to intergranular brittle fracture with the increase of the deformation temperature and the strain rate. It is made out that the precipitation of LiH is the fundamental reason for the intergranular brittle fracture of the 1420 Al-Li alloy at high temperature. The mechanism of hydrogen embrittlement of the 1420 Al-Li alloy at high temperature was discussed, and it was proposed that the hydrogen embrittlement at high temperature is an integrated function of the dynamic and the static force, which enrichs the theories of hydrogen embrittlement.

  20. Critical Deposition Condition of CoNiCrAlY Cold Spray Based on Particle Deformation Behavior

    Science.gov (United States)

    Ichikawa, Yuji; Ogawa, Kazuhiro

    2017-02-01

    Previous research has demonstrated deposition of MCrAlY coating via the cold spray process; however, the deposition mechanism of cold spraying has not been clearly explained—only empirically described by impact velocity. The purpose of this study was to elucidate the critical deposit condition. Microscale experimental measurements of individual particle deposit dimensions were incorporated with numerical simulation to investigate particle deformation behavior. Dimensional parameters were determined from scanning electron microscopy analysis of focused ion beam-fabricated cross sections of deposited particles to describe the deposition threshold. From Johnson-Cook finite element method simulation results, there is a direct correlation between the dimensional parameters and the impact velocity. Therefore, the critical velocity can describe the deposition threshold. Moreover, the maximum equivalent plastic strain is also strongly dependent on the impact velocity. Thus, the threshold condition required for particle deposition can instead be represented by the equivalent plastic strain of the particle and substrate. For particle-substrate combinations of similar materials, the substrate is more difficult to deform. Thus, this study establishes that the dominant factor of particle deposition in the cold spray process is the maximum equivalent plastic strain of the substrate, which occurs during impact and deformation.

  1. Flow Behavior and Microstructural Evolution of 7A85 High-Strength Aluminum Alloy During Hot Deformation

    Science.gov (United States)

    Liu, Xingang; Han, Shuang; Chen, Lei; Yang, Shuai; Jin, Miao; Guo, Baofeng; Mao, Tianhong

    2017-02-01

    Hot deformation behavior of 7A85 high-strength aluminum alloy was investigated at 593 K to 713 K (320 °C to 440 °C) and 0.01-10 s-1. The manifestation of flow curves was related to the strain rate. Typical single-peak curves were shown below 10 s-1, while two stress peaks appeared in the case of 10 s-1 and the second peak strain was almost three times larger than the first one. A constitutive equation considering the effect of strain was developed. Flow stress values predicted by the constitutive model demonstrated a good agreement with the experimental results over the entire range of strain rates and temperatures. Microstructure characterization revealed that dynamic recovery (DRV) and continuous dynamic recrystallization (CDRX) which depended on the Zener-Hollomon parameter (Z) closely, co-occurred at large strain (ɛ = 0.7). With decreasing Z-value, the dominant dynamic restoration mechanism gradually transformed from DRV to CDRX. The average subgrain size (d sub) showed a power-law relationship with Z. Recrystallization was sensitively dependent on the strain rate at above 683 K (410 °C). The fine equiaxed grains appeared at original grain boundaries and in deformed grains interior owing to CDRX. The high-curvature subgrain boundaries can also cause the nucleation of recrystallization within deformed grains.

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

    Science.gov (United States)

    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+weak 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+weak, which later changed to a 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 observed to proceed from the

  3. The influence of silicon and aluminum on austenite deformation behavior during fatigue and tensile loading

    Science.gov (United States)

    Lehnhoff, Gregory R.

    Advanced high strength steels (AHSS) for automobile light-weighting utilize Si and Al alloying to retain austenite in the microstructure during thermal partitioning treatments. This research project utilized fully austenitic steels with varied Si and Al compositions to understand the effect of these elements on austenite deformation response, including deformation induced martensite formation and deformation twinning. Specific focus was directed at understanding austenite deformation response during fatigue loading. Independent alloying additions of 2.5 wt pct Si and Al were made to a base steel composition of 15 Ni - 11 Cr - 1 Mn - 0.03 C (wt pct). Weak beam dark field transmission electron microscopy (TEM) imaging of dissociated dislocations was implemented to experimentally determine the influences of Si and Al on austenite stacking fault energy (SFE). The 2.5 wt pct Si alloying addition decreased the SFE by 6.4 mJ/m2, while the 2.5 wt pct Al alloying increased the SFE by 12 mJ/m2. Fully reversed, total strain controlled, low cycle fatigue (LCF) tests indicated that all four alloys underwent primary cyclic hardening and stabilization. Secondary cyclic strain hardening was correlated to BCC martensite formation using Feritscope magnetic fraction measurements of LCF specimens; the formation of 1 pct martensite led to 7 MPa of secondary hardening. TEM showed that martensite predominantly formed as parallel, irregular bands through strain induced nucleation on austenite shear bands. The austenite shear bands consisted of austenite {111} planes with concentrated dislocations, stacking faults, and/or HCP epsilon-martensite. Aluminum alloying promoted martensite formation during LCF, while Si suppressed martensite. Therefore, the strain induced nucleation process was not suppressed by the increased SFE associated with Al alloying. Tensile testing indicated that Si alloying promoted deformation twinning by lowering the SFE. Similarly to LCF loading, Al promoted

  4. Effect of Cyclic Pre-deformation on Uniaxial Tensile Behavior of Cu-16 at. pct Al Alloy with Low Stacking Fault Energy

    Science.gov (United States)

    Yan, Y.; Qi, C. J.; Han, D.; Ji, H. M.; Zhang, M. Q.; Li, X. W.

    2017-02-01

    To explore the effect of cyclic pre-deformation on static mechanical behavior of materials with different stacking fault energies (SFEs), polycrystalline Cu-16 at. pct Al alloy with a low SFE is selected as the target material in the present work, and the strengthening micro-mechanisms induced by cyclic pre-deformation are compared with the previous studies on pure Al with a high SFE and Cu with an intermediate SFE. The results show that the movement of dislocations exhibits a high slip planarity during cyclic pre-deformation at different total strain amplitudes Δ ɛ t/2, and some nano-sized deformation twins are formed after subsequent tension. The cyclic pre-deformation at an appropriate Δ ɛ t/2 of 1.0 × 10-3 promotes a significant increase in ultimate tensile strength σ UTS nearly without loss of tensile ductility, which primarily stems from the introduction of many mobile planar slip dislocations by cyclic pre-deformation as well as the formation of nano-sized deformation twins during subsequent tension. Based on the comparison of the strengthening micro-mechanisms induced by cyclic pre-deformation in Al, Cu, and Cu-16 at. pct Al alloy, it is deduced that a low-cycle cyclic pre-deformation at an appropriate condition is expected to cause a better strengthening effect on the static tensile properties of low SFE metals.

  5. Hot Deformation Behavior and Microstructural Evolution of a Medium Carbon Vanadium Microalloyed Steel

    Science.gov (United States)

    Cutrim, Rialberth M.; Rodrigues, Samuel F.; Reis, Gedeon S.; Silva, Eden S.; Aranas, Clodualdo; Balancin, Oscar

    2016-11-01

    Hot forging of steel requires application of large strains, under which conditions, dynamic recrystallization (DRX) is expected to take place. In this study, torsion tests were carried out on a medium carbon vanadium microalloyed steel (38MnSiVS5) to simulate hot forging. Deformations were applied isothermally in the temperature range 900-1200 °C at strain rates of 0.1-10 s-1 in order to observe for the occurrence of DRX and to investigate for the microstructural evolution during straining. The shape of the flow curves indicated that the recrystallization takes place during deformation. This was supported by optical microscopy performed on the quenched samples which displayed considerable amounts of recrystallized grains. It was shown that the grain size depends on straining conditions such as strain rate and temperature. Finally, it was revealed that these process parameters can considerably affect the evolution of microstructure of industrial grade steels by means of DRX.

  6. Experimental and Numerical Investigations on Strength and Deformation Behavior of Cataclastic Sandstone

    Science.gov (United States)

    Zhang, Y.; Shao, J. F.; Xu, W. Y.; Zhao, H. B.; Wang, W.

    2015-05-01

    This work is devoted to characterization of the deformation and strength properties of cataclastic sandstones. Before conducting mechanical tests, the physical properties were first examined. These sandstones are characterized by a loose damaged microstructure and poorly cemented contacts. Then, a series of mechanical tests including hydrostatic, uniaxial, and triaxial compression tests were performed to study the mechanical strength and deformation of the sandstones. The results obtained show nonlinear stress-strain responses. The initial microcracks are closed at hydrostatic stress of 2.6 MPa, and the uniaxial compressive strength is about 0.98 MPa. Under triaxial compression, there is a clear transition from volumetric compressibility to dilatancy and a strong dependency on confining pressure. Based on the experimental evidence, an elastoplastic model is proposed using a linear yield function and a nonassociated plastic potential. There is good agreement between numerical results and experimental data.

  7. Repeated Load Permanent Deformation Behavior of Mixes With and Wihtout Modified Bituments

    Directory of Open Access Journals (Sweden)

    Imran Hafeez

    2011-01-01

    Full Text Available Premature rutting in flexible pavement structure is being observed on most of the road network of Pakistan. It initiates primarily due to uncontrolled axle loading and high ambient temperatures. NHA (National Highway Authority, Pakistan has continuously been modifying aggregate gradations and penetration grade of bitumen, without any prior investigation of the mix behaviour under the prevailing axle load and environmental conditions of the country. A comprehensive laboratory investigation was carried out on six mixes ranging from finer to coarser. Specimens were subjected to cyclic loading on UTM-5P (Universal Testing Machine to study the resistance against permanent deformation of the mixes at 25, 40 and 550C. At low temperatures and stress levels, both coarse and fine graded mixes showed less accumulated strain, whereas at higher temperatures and stress levels, coarse graded mix with PMB (Polymer Modified Bitumen showed good resistance to permanent deformation.

  8. Inelastic deformation behavior of thermal barrier coatings exposed at a high-temperature environment

    Directory of Open Access Journals (Sweden)

    Arai M.

    2010-06-01

    Full Text Available Thermal barrier coatings (TBCs are usually deposited onto the surface of the high-temperature component such as gas turbine, in order to protect it from a hightemperature environment. Coating stress generated by such a high-temperature brings serious damages in TBCs in service. For predicting numerically it, it is necessary to develop the constitutive equation suite to plasam-sprayed TBCs. Previous studies have made clear that the freestanding ceramic coat peeled from TBC coated substrate deforms nonlinearly with a mechanical loading, however the results there have been restricted to the test done using as-sprayed sample. In this study, effect of deposition parameter and high-temperature exposure condition on stress-strain curve of the freestanding ceramic coating sample was examined. The associated deformation process was discussed with the microstructure changes observed after performing a bending test for the exposed sample.

  9. Deformation of Semi-Solid Metals - Refining, Strengthening, and Rheological Behavior.

    Science.gov (United States)

    1982-07-15

    described. This work extends earlier studies on " Rheocasting " and has broad, practical implications. The original Rheocast work, sponsored by ARO, led to... Rheocasting has now finally become a commercial reality. The broad area of forming and otherwise processing of metals in the semi-solid state is one that...than Rheocasting , for forming metals in their semi-solid state. And we wondered as well if we might find some way, through deformation in the semi-solid

  10. Superplastic Deformation Behavior of Hot-rolled AZ31 Magnesium Alloy Sheet at Elevated Temperatures

    Institute of Scientific and Technical Information of China (English)

    ZHANG Kaifeng; YIN Deliang; WANG Guofeng; HAN Wenbo

    2006-01-01

    Uniaxial tensile tests were carried out in the temperature range of 250-450 ℃ and the strain rate range of 0.7×10-3-1.4×10-1s-1 to evaluate the superplasticity of AZ31 Mg alloy. The threshold stress which characterizes the difficulty for grain boundary sliding was calculated at various temperatures. The surface relieves of superplastically deformed specimens were observed by using a scanning electronic microscope (SEM). Results show that, at the temperature of 400 ℃ and strain rate of 0.7×10-3 s-1, the strain rate sensitivity exponent, i e, m value reaches 0.47 and the maximum elongation of 362.5% is achieved. Grain boundary sliding (GBS) is the primary deformation mechanism and characterized by a pronounced improvement in the homogeneity with increasing temperatures. A large number of filaments were formed at the end of deformation and intergranular cavities were produced with the necking and fracture of filaments. Finally, the model for the formation of intergranular cavities was proposed.

  11. The role of deformation twinning in the fracture behavior and mechanism of basal textured magnesium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ando, D., E-mail: dando@material.tohoku.ac.jp; Koike, J.; Sutou, Y.

    2014-04-01

    AZ31 magnesium alloys were deformed to 10% and to failure strain by tensile loading at room temperature. Scribed grids were drawn by a focused ion beam system (FIB) to visualize the local deformation in each grain. This showed that the magnitude of the strain was distributed non-uniformly in each grain. It was found that the low-strain grains accompanied {10–12} twins, while the severely strained grains accompanied {10–11}–{10–12} double twins. Cracks nucleated at the double twins and tended to propagate along {10–12} twin interfaces as well as within grains. Furthermore, fractography revealed three types of microstructural features: dimples, elliptic facets and sheared dimples. Most abundant were the dimples formed by ductile failure. The elliptic facets appeared to be due to crack propagation along the {10–12} twin interfaces. The sheared dimples were frequently observed in connection with localized shear deformation within the double twins. These results led us to conclude that premature and catastrophic failure of Mg alloys is mainly associated with double twins. Prevention of double twinning is essential to improve the ductility of Mg alloys.

  12. Numerical simulation of plastic behavior and meso inhomogeneous deformation in AZ31 Mg alloy%AZ31镁合金晶体塑性行为与细观非均匀变形的数值模拟

    Institute of Scientific and Technical Information of China (English)

    蓝永庭; 陆大敏; 刘贵龙; 苏莹; 张克实

    2014-01-01

    The constitutive relation of Mg alloy was established with the crystal plasticity theory based on the mechanisms of slip and twinning deformations. The hardening functions of slip and twinning deformations were proposed in consideration of the interaction between the slip and twinning deformation. The numerical simulation and meso analysis for AZ31 Mg alloy under the uniaxial loading were carried out using the above constitutive relation and the hardening functions associated with a representative volume element (RVE) consisting of Voronoi polycrystalline aggregation. By comparing the simulation results and the experimental data, the present method is verified feasible to predict reasonably the macroscopic yield behavior, the hardening evolution and the polycrystalline texture evolution. The reasonable estimations for inhomogeneous rotation of grain orientation and the twin volume fraction in the polycrystalline can be attained. The results show that, the macroscopic plastic behavior of Mg alloy depends on the competitive result of activation slip and twinning systems; the tension twin deformation is the primary reason to the formation of typical (0001) basal texture in the polycrystalline; and the twin deformation leads to extremely inhomogeneous distribution for the orientation deflection and the twin volume fraction in the polycrystalline.%同时考虑滑移与孪生变形机制,在晶体塑性理论基础上建立镁合金晶体本构关系,分别提出滑移与孪生变形的硬化函数,并考虑滑移与孪生变形间的交互作用;结合Voronoi多晶集合体代表性体积单元(RVE),对AZ31镁合金材料在单轴加载情形下进行数值模拟实验及细观分析。比较模拟结果与实验数据表明:采用晶体塑性本构关系及硬化函数能够合理预测镁合金宏观屈服行为、硬化演化与多晶织构演化,并可合理估计多晶体内的晶粒取向不均匀转动及晶粒内产生孪晶的体积分数分布

  13. [The deformation behavior of human lumbar intervertebral discs subjected to long term axial dynamic compressive forces (author's transl)].

    Science.gov (United States)

    Köller, W; Funke, F; Hartmann, F

    1981-04-01

    49 specimens were studied in 67 axial compression tests; the duration test varied between 2 and 6 hours. All discs showed marked creep; after a big decrease in the first minutes the rate of creep decreases still slightly. Additional the results reveal a decreasing axial deformability with time. In the beginning of a test quickly the viscoelastic behavior alters to such a steady state that the disc behaves more like an elastic body. Loss of mass normally observed after compression tests is due to loss of liquid, but liquid absorption during mechanical load is possible too. The long term biochmechanical behavior is reproducible very well; a second experiment done with the same disc yields nearly the same results.

  14. On the effect of x-ray irradiation on the deformation and fracture behavior of human cortical bone

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Holly D.; Launey, Maximilien E.; McDowell, Alastair A.; Ager III, Joel W.; Ritchie, Robert O.

    2010-01-10

    In situ mechanical testing coupled with imaging using high-energy synchrotron x-ray diffraction or tomography imaging is gaining in popularity as a technique to investigate micrometer and even sub-micrometer deformation and fracture mechanisms in mineralized tissues, such as bone and teeth. However, the role of the irradiation in affecting the nature and properties of the tissue is not always taken into account. Accordingly, we examine here the effect of x-ray synchrotron-source irradiation on the mechanistic aspects of deformation and fracture in human cortical bone. Specifically, the strength, ductility and fracture resistance (both work-of-fracture and resistance-curve fracture toughness) of human femoral bone in the transverse (breaking) orientation were evaluated following exposures to 0.05, 70, 210 and 630 kGy irradiation. Our results show that the radiation typically used in tomography imaging can have a major and deleterious impact on the strength, post-yield behavior and fracture toughness of cortical bone, with the severity of the effect progressively increasing with higher doses of radiation. Plasticity was essentially suppressed after as little as 70 kGy of radiation; the fracture toughness was decreased by a factor of five after 210 kGy of radiation. Mechanistically, the irradiation was found to alter the salient toughening mechanisms, manifest by the progressive elimination of the bone's capacity for plastic deformation which restricts the intrinsic toughening from the formation 'plastic zones' around crack-like defects. Deep-ultraviolet Raman spectroscopy indicated that this behavior could be related to degradation in the collagen integrity.

  15. The influence of martensite shape, concentration, and phase transformation strain on the deformation behavior of stable dual-phase steels

    Science.gov (United States)

    Bhattacharyya, A.; Sakaki, T.; Weng, G. J.

    1993-02-01

    A continuum model is developed to examine the influence of martensite shape, volume fraction, phase transformation strain, and thermal mismatch on the initial plastic state of the ferrite matrix following phase transformation and on the subsequent stress-strain behavior of the dual-phase steels upon loading. The theory is developed based on a relaxed constraint in the ductile matrix and an energy criterion to define its effective stress. In addition, it also assumes the martensite islands to possess a spheroidal shape and to be randomly oriented and homogenously dispersed in the ferrite matrix. It is found that for a typical water-quenched process from an intercritical temperature of 760 °C, the critical martensite volume fraction needed to induce plastic deformation in the ferrite matrix is very low, typically below 1 pct, regardless of the martensite shape. Thus, when the two-phase system is subjected to an external load, plastic deformation commences immediately, resulting in the widely observed “continuous yielding” behavior in dual-phase steels. The subsequent deformation of the dual-phase system is shown to be rather sensitive to the martensite shape, with the disc-shaped morphology giving rise to a superior overall response (over the spherical type). The stress-strain relations are also dependent upon the magnitude of the prior phase transformation strain. The strength coefficient h and the work-hardening exponent n of the smooth, parabolic-type stress-strain curves of the dual-phase system also increase with increasing martensite content for each selected inclusion shape. Comparison with an exact solution and with one set of experimental data indicates that the theory is generally within a reasonable range of accuracy.

  16. Effects of carbon and nitrogen on the tensile deformation behavior of SUS304 and 316 stainless steels at cryogenic temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Miura, Ritsu; Ohnishi, Keizo; Nakajima, Hideo; Shimamoto, Susumu

    1987-04-01

    Effects of C and N contents on the tensile properties and deformation behaviors at low temperatures have been investigated to obtain an alloy design basis on SUS 304 and 316 austenitic stainless steels for cryogenic application. Increase in C and N contents led to the increase in temperature dependency of 0.2% yield strength for both SUS 304 and 316 steels. However, SUS 316 steel showed larger temperature dependency than SUS 304 at the same level of (C + N) content, probably due to the solution strengthening effect of Mo. The results of multiple regression analyses on the effects of C and N contents on the 0.2% yield strength at each temperature indicated that the contributions of both C and N increase with decreasing temperature and that the contribution of N is larger than that of C at low temperatures. The deformation behavior of metastable austenitic steels could be comprehensively explained in relation to austenite stability. Increase in austenite stability resulted in increase in onset strain at which strain-induced martensitic transformation occurred. And increase in austenite stability also led to the decrease in transformation rate which in turn gave rise to lowering strain-hardening exponent. It has been also found that tensile elongation shows maximum at around M/sub d30/ temperature.

  17. The effect of various deformation processes on the corrosion behavior of casing and tubing carbon steels in sweet environment

    Science.gov (United States)

    Elramady, Alyaa Gamal

    The aim of this research project is to correlate the plastic deformation and mechanical instability of casing steel materials with corrosion behavior and surface change, in order to identify a tolerable degree of deformation for casing steel materials. While the corrosion of pipeline and casing steels has been investigated extensively, corrosion of these steels in sweet environments with respect to plastic deformation due to bending, rolling, autofrettage, or handling needs more investigation. Downhole tubular expansion of pipes (casings) is becoming standard practice in the petroleum industry to repair damaged casings, shutdown perforations, and ultimately achieve mono-diameter wells. Tubular expansion is a cold-drawing metal forming process, which consists of running conical mandrels through casings either mechanically using a piston or hydraulically by applying a back pressure. This mechanism subjects the pipes to large radial plastic deformations of up to 30 pct. of the inner diameter. It is known that cold-working is a way of strengthening materials such as low carbon steel, but given that this material will be subjected to corrosive environments, susceptibility to stress corrosion cracking (SCC) should be investigated. This research studies the effect of cold-work, in the form of cold-rolling and cold-expansion, on the surface behavior of API 5CT steels when it is exposed to a CO2-containing environment. Cold-work has a pronounced influence on the corrosion behavior of both API 5CT K55 and P110 grade steels. The lowest strength grade steel, API 5CT K55, performed poorly in a corrosive environment in the slow strain rate test. The ductile material exhibited the highest loss in strength and highest susceptibility to stress corrosion cracking in a CO 2-containing environment. The loss in strength declined with cold-rolling, which can be ascribed to the surface compressive stresses induced by cold-work. On the other hand, API 5CT P110 grade steels showed higher

  18. Mechanical behavior of materials engineering methods for deformation, fracture, and fatigue

    CERN Document Server

    Dowling, Norman E

    2012-01-01

    For upper-level undergraduate engineering courses in Mechanical Behavior of Materials. Mechanical Behavior of Materials, 4/e introduces the spectrum of mechanical behavior of materials, emphasizing practical engineering methods for testing structural materials to obtain their properties, and predicting their strength and life when used for machines, vehicles, and structures. With its logical treatment and ready-to-use format, it is ideal for upper-level undergraduate students who have completed elementary mechanics of materials courses.

  19. Deformation behavior and dynamic recrystallization of Mg-Y-Nd-Gd-Zr alloy

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xin; ZHANG Kui; LI Xinggang; LI Yongjun; HE Qingbiao; SUN Jianfeng

    2008-01-01

    The characteristics of dynamic reerystallization (DRX) in Mg-Y-Nd-Gd-Zr-RE magnesium alloy were investigated by compres-sion tests at temperatures between 523 and 723 K and at strain rates ranging from 0.002 to 1 s-1 with maximum strain of 0.693. The strain-hardening rate can be obtained from true stress-true strain curves, plots of θ-σ,-(θ/ σ)-σ and lnθ-σ in different compression conditions were obtained by further study. The critical condition of the onset of DRX process was determined as ((/ σ)(-θ/ σ))=0. In the range of the above deformation temperature and strain rate, the ratio of critical stress (σc) to peak stress (am) and critical strain (εc) to the peak strain (εm) stood at σc/σm=0.62-0.89 and εc/εm=0.11-0.37, respectively. DRX could be observed during hot deformation process, microstructure evolution of the magnesium alloy at different temperatures and strain rates were studied with the aid of optical microscope(OM), and the average recrystal-lized grain size was measured by means of intercepts on photomicrographs. It was shown that the average dynamically recrystallized grain size (drec) changed with different deformation parameters, the natural logarithm of the average recrystallized grain size varied linearly with the natural logarithm of Zener-Hollomon parameter; the peak stress changed with the average recrystallized grain size, and the natural loga-rithm of the average recrystallized grain size varied linearly with the natural logarithm of the peak stress.

  20. Evaluation of the thermal-hydraulic response and fuel rod thermal and mechanical deformation behavior during the power burst facility test LOC-3. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    Yackle, T.R.; MacDonald, P.E.; Broughton, J.M.

    1980-01-01

    An evaluation of the results from the LOC-3 nuclear blowdown test conducted in the Power Burst Facility is presented. The test objective was to examine fuel and cladding behavior during a postulated cold leg break accident in a pressurized water reactor (PWR). Separate effects of rod internal pressure and the degree of irradiation were investigated in the four-rod test. Extensive cladding deformation (ballooning) and failure occurred during blowdown. The deformation of the low and high pressure rods was similar; however, the previously irradiated test rod deformed to a greater extent than a similar fresh rod exposed to identical system conditions.

  1. Modeling Transverse Behavior of Kevlar® KM2 Single Fibers with Deformation-induced Damage

    OpenAIRE

    Cheng, Ming; Chen, Weinong

    2006-01-01

    Abstract A phenomenological continuum model is adapted to describe the transverse mechanical behavior of Kevlar? KM2 single fibers in compression. This model could be used for numerical simulations of the mechanical behaviors of fabrics made of Kevlar? KM2 fibers. An equivalent fiber model is used to form the phenomenological model in terms of nominal stress and nominal stretch ratio. Thi...

  2. A numerical and experimental study of temperature effects on deformation behavior of carbon steels at high strain rates

    Science.gov (United States)

    Pouya, M.; Winter, S.; Fritsch, S.; F-X Wagner, M.

    2017-03-01

    Both in research and in the light of industrial applications, there is a growing interest in methods to characterize the mechanical behavior of materials at high strain rates. This is particularly true for steels (the most important structural materials), where often the strain rate-dependent material behavior also needs to be characterized in a wide temperature range. In this study, we use the Finite Element Method (FEM), first, to model the compressive deformation behavior of carbon steels under quasi-static loading conditions. The results are then compared to experimental data (for a simple C75 steel) at room temperature, and up to testing temperatures of 1000 °C. Second, an explicit FEM model that captures wave propagation phenomena during dynamic loading is developed to closely reflect the complex loading conditions in a Split-Hopkinson Pressure Bar (SHPB) – an experimental setup that allows loading of compression samples with strain rates up to 104 s-1 The dynamic simulations provide a useful basis for an accurate analysis of dynamically measured experimental data, which considers reflected elastic waves. By combining numerical and experimental investigations, we derive material parameters that capture the strain rate- and temperature-dependent behavior of the C75 steel from room temperature to 1000 °C, and from quasi-static to dynamic loading.

  3. Deformation behaviors of magnesium alloy AZ31 sheet in cold deep drawing

    Institute of Scientific and Technical Information of China (English)

    YANG Lian-fa; MORI Ken-ichiro; TSUJI Hirokazu

    2008-01-01

    To investigate how the popular magnesium alloy AZ31 sheet (aluminum 3%, zinc 1%) behaves in cold working, deep drawing experiments at room temperature, along with finite element(FE) simulation,were performed on the cold forming sheet of the AZ31 alloy after being annealed under various conditions. The activities were focused on the fracture pattern, limit drawing ratio(LDR), deformation load, thickness distribution, anisotropic effect, as well as the influences of the annealing conditions and tool configuration on them. The results display that punch shoulder radius instead of die clearance, has much influence on the thickness distribution. The anisotropy is remarkable in cold working, which adversely impacts the LDR. The fracture often happens on the side wall at an angle to axis of the deformed specimen. The results also imply that the LDR for the material under present experimental conditions is 1.72, and annealing the material at 450 ℃ for 1 h may be preferable for the cold deep drawing.

  4. Hydrodynamic description of (visco)elastic composite materials and relative strains as a new macroscopic variable

    CERN Document Server

    Menzel, Andreas M

    2016-01-01

    One possibility to adjust material properties to a specific need is to embed units of one substance into a matrix of another substance. Even materials that are readily tunable during operation can be generated in this way. In (visco)elastic substances, both the matrix material as well as the inclusions and/or their immediate environment can be dynamically deformed. If the typical dynamic response time of the inclusions and their surroundings approach the macroscopic response time, their deformation processes need to be included into a dynamic macroscopic characterization. Along these lines, we present a hydrodynamic description of (visco)elastic composite materials. For this purpose, additional strain variables reflect the state of the inclusions and their immediate environment. These additional strain variables in general are not set by a coarse-grained macroscopic displacement field. Apart from that, during our derivation, we also include the macroscopic variables of relative translations and relative rotat...

  5. A novel unified dislocation density-based model for hot deformation behavior of a nickel-based superalloy under dynamic recrystallization conditions

    Science.gov (United States)

    Lin, Y. C.; Wen, Dong-Xu; Chen, Ming-Song; Chen, Xiao-Min

    2016-09-01

    In this study, a novel unified dislocation density-based model is presented for characterizing hot deformation behaviors in a nickel-based superalloy under dynamic recrystallization (DRX) conditions. In the Kocks-Mecking model, a new softening item is proposed to represent the impacts of DRX behavior on dislocation density evolution. The grain size evolution and DRX kinetics are incorporated into the developed model. Material parameters of the developed model are calibrated by a derivative-free method of MATLAB software. Comparisons between experimental and predicted results confirm that the developed unified dislocation density-based model can nicely reproduce hot deformation behavior, DRX kinetics, and grain size evolution in wide scope of initial grain size, strain rate, and deformation temperature. Moreover, the developed unified dislocation density-based model is well employed to analyze the time-variant forming processes of the studied superalloy.

  6. A coupled analysis of fluid flow, heat transfer and deformation behavior of solidifying shell in continuously cast beam blank

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung Eui; Yeo, Tae Jung; Oh, Kyu Hwan; Yoon, Jong Kyu [School of Materials Science and Engineering, Seoul Nat`l Univ., Seoul (Korea, Republic of); Han, Heung Nam [Oxford Center for Advanced Materials and Composites, Department of Materials, Univ. of Oxford (United Kingdom)

    1997-12-31

    A mathematical model for a coupled analysis of fluid flow, heat transfer and deformation behavior in the continuously cast beam blank has been developed. The fluid flow, heat transfer and solidification in the mold region were analyzed with 3-dimensional finite difference method (FDM) based on control volume method. A body fitted coordinate system was introduced for the complex geometry of the beam blank. The effects of turbulence and natural convection of molten steel were taken into account in determining the fluid flow in the strand. The thermo-elasto-plastic deformation behavior in the cast strand and the formation of air gap between the solidifying shell and the mold were analyzed by the finite element method (FEM) using the 2-dimensional slice temperature profile calculated by the FDM. The heat flow between the strand and the mold was evaluated by the coupled analysis between the fluid flow-heat transfer analysis and the thermo-elasto-plastic stress analysis. In order to determine the solid fraction in the mushy zone, the microsegregation of solute element was assessed. The effects of fluid flow on the heat transfer, the solidification of steel and the distribution of shell thickness during the casting of the beam blank were simulated. The deformation behavior of the solidifying shell and the possibility of cracking of the strand were also investigated. The recirculating flows were developed in the regions of the web and the flange tip. The impinging of the inlet flow from the nozzle retarded the growing of solidifying shell in the regions of the fillet and the flange. The air gap between the strand and the mold was formed near the region of the corner of the flange tip. At the initial stage of casting, the probability of the surface cracking was high in the regions of the fillet and the flange tip. After the middle stage of casting, the internal cracking was predicted in the regions of the flange tip, and between the fillet and the flange tip. (author) 38

  7. Effects of low temperature neutron irradiation on deformation behavior of austenitic stainless steels

    Energy Technology Data Exchange (ETDEWEB)

    Pawel, J.E.; Rowcliffe, A.F.; Alexander, D.J.; Grossbeck, M.L. [Oak Ridge National Laboratory, TN (United States); Shiba, K.

    1996-04-01

    An austenitic stainless steel, designated 316LN-IG, has been chosen for the first wall/shield (FW/S) structure for the International Thermonuclear Experimental Reactor (ITER). The proposed operational temperature range for the structure (100 to 250{degree}C) is below the temperature regimes for void swelling (400-600{degree}C) and for helium embrittlement (500-700{degree}C). However, the proposed neutron dose is such that large changes in yield strength, deformation mode, and strain hardening capacity could be encountered which could significantly affect fracture properties. Definition of the irradiation regimes in which this phenomenon occurs is essential to the establishment of design rules to protect against various modes of failure.

  8. Behavior of highly deformable relaxor-ferroelectric-based ceramics in an electric field

    Science.gov (United States)

    Talanov, M. V.; Reznichenko, L. A.

    2013-10-01

    The deformation characteristics of multicomponent barium-doped piezoelectric ceramics mPbMg1/3Nb2/3O3- n PbNi1/3Nb2/3O3- y PbZn1/3Nb2/3O3- x PbTiO3 are studied in electric fields E = 0-12 kV/cm. Anomalies are detected in the dependences of elastic strain ξ3 and piezoelectric modulus d {33/eff} on the external dc electric field. The history of the materials is shown to affect the change of piezoelectric modulus d {33/eff} in an electric field. The revealed dependences are used to propose a method to increase the efficiency of operation of piezoelectric actuators.

  9. Dynamic behavior of a rotating delaminated composite beam including rotary inertia and shear deformation effects

    Directory of Open Access Journals (Sweden)

    Ramazan-Ali Jafari-Talookolaei

    2015-09-01

    Full Text Available A finite element (FE model is developed to study the free vibration of a rotating laminated composite beam with a single delamination. The rotary inertia and shear deformation effects, as well as the bending–extension, bending–twist and extension–twist coupling terms are taken into account in the FE model. Comparison between the numerical results of the present model and the results published in the literature verifies the validity of the present model. Furthermore, the effects of various parameters, such as delamination size and location, fiber orientation, hub radius, material anisotropy and rotating speed, on the vibration of the beam are studied in detail. These results provide useful information in the study of the free vibration of rotating delaminated composite beams.

  10. Large-deformation and long-time behavior of entangled melts in complex geometries

    Science.gov (United States)

    Zhu, Xiangyang; Wang, Shi-Qing

    2012-02-01

    Recent particle-tracking velocimetric (PTV) observations have revealed strain localization either during startup shear beyond the stress overshoot or after a large step shear of entangled polymers [e.g., Macromolecules, 42, 6261 (2009)]. The physical pictures leading to these decohesion events have been put forward [J. Chem. Phys. 127, 064903(2007); J. Rheol. 53, 1389 (2009)]. In this presentation we apply the particle-tracking velocimetric method [Macromol. Mater. Engr. 292, 15 (2007)] to study similar strain localization phenomena originating from yielding of the entanglement network in other forms of deformation including uniaxial extension, ``squeeze flow'' and extrusion of polymers from a wide open space into a narrow opening. The striking discontinuities in the velocity profile can all be understood in terms of a shear yielding criterion. The research is funded, in part, by a grant from the National Science Foundation (CMMI-0926522)

  11. Cyclic Deformation Behavior and Fatigue Crack Propagation of Low Carbon Steel Prestrained in Tension

    Directory of Open Access Journals (Sweden)

    J. G. Wang

    2009-01-01

    Full Text Available The tests were performed on low carbon steel plate. In the tension fatigue tests, two angle values (ϕ=0° and ϕ=45°, ϕ is the angle between the loading and the rolling direction have been chosen. The influence of strain path change on the subsequent initial work softening rate and the saturation stress has been investigated. Dislocation microstructure was observed by transmission electron microscopy. It was found that the strain amount of preloading in tension has obviously affected the cyclic softening phenomenon and the initial cyclic softening rate. It was observed that the reloading axial stress for ϕ=45° case increased more than that of ϕ=0° case, due to the anisotropism of Q235. In the fatigue crack propagation tests, the experimental results show that with increasing the pretension deformation degree, the fatigue crack growth rate increases, especially at the near threshold section.

  12. Characterization of Hot Deformation Behavior of a Fe-Cr-Ni-Mo-N Superaustenitic Stainless Steel Using Dynamic Materials Modeling

    Science.gov (United States)

    Pu, Enxiang; Zheng, Wenjie; Song, Zhigang; Feng, Han; Zhu, Yuliang

    2017-02-01

    Hot deformation behavior of a Fe-24Cr-22Ni-7Mo-0.5N superaustenitic stainless steel was investigated by hot compression tests in a wide temperature range of 950-1250 °C and strain rate range of 0.001-10 s-1. The flow curves show that the flow stress decreases as the deformation temperature increases or the strain rate decreases. The processing maps developed on the basis of the dynamic materials model and flow stress data were adopted to optimize the parameters of hot working. It was found that the strain higher than 0.2 has no significant effect on the processing maps. The optimum processing conditions were in the temperature range of 1125-1220 °C and strain rate range of 0.1-3 s-1. Comparing to other stable domains, microstructural observations in this domain revealed the complete dynamic recrystallization (DRX) with finer and more uniform grain size. Flow instability occurred in the domain of temperature lower than 1100 °C and strain rate higher than 0.1 s-1.

  13. Late Quaternary surface deformation and rupture behavior of strong earthquake on the segment north of Mianning of the Anninghe fault

    Institute of Scientific and Technical Information of China (English)

    RAN YongKang; CHEN LiChun; CHENG JianWu; GONG HuiLing

    2008-01-01

    The Anninghe fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block, and the study of its surface deformation and rupture behavior during strong earthquake in the late Quaternary is of fundamental importance for understanding the future seismic risk of the fault zone or even the entire western Sichuan region.Using the methods of detailed geomorphic and geological survey, digital image analysis, total station instrument survey, excavation of combined trench and dating, we analyze the geomorphologic sequences of the offset strata at several sites where the late Quaternary deformation remnants are fairly well preserved and obtain some new results as follows: Strong earthquake events with left-lateral displacements of about 3 m occurred at the two sites of Zimakua and Yejitong at 1634-1811,1030-1050 and 280-550 a BP, respectively, and the recurrence interval is 520-660 a; The youngest event in the area of Dahaizi-Ganhaizi should be the earthquake of 1536, other events are at 1768-1826, 2755-4108 and 4108-6593 a BP, respectively, with a recurrence interval of 1300-1900 a.The strong earthquake activity shows a clustering character.The possibility of occurrence of a strong earthquake exists on the north segment of the Anninghe fault sometime in the future.

  14. Late Quaternary surface deformation and rupture behavior of strong earthquake on the segment north of Mianning of the Anninghe fault

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Anninghe fault is an important active fault along the eastern boundary of Sichuan-Yunnan active tectonic block, and the study of its surface deformation and rupture behavior during strong earthquake in the late Quaternary is of fundamental importance for understanding the future seismic risk of the fault zone or even the entire western Sichuan region. Using the methods of detailed geomorphic and geological survey, digital image analysis, total station instrument survey, excavation of combined trench and dating, we analyze the geomorphologic sequences of the offset strata at several sites where the late Quaternary deformation remnants are fairly well preserved and obtain some new results as follows: Strong earthquake events with left-lateral displacements of about 3 m occurred at the two sites of Zimakua and Yejitong at 1634-1811, 1030-1050 and 280-550 a BP, respectively, and the recurrence interval is 520-660 a; The youngest event in the area of Dahaizi-Ganhaizi should be the earthquake of 1536, other events are at 1768-1826, 2755-4108 and 4108-6593 a BP, respectively, with a recurrence interval of 1300-1900 a. The strong earthquake activity shows a clustering character. The possibility of occurrence of a strong earthquake exists on the north segment of the Anninghe fault sometime in the future.

  15. Microstructure and hot deformation behavior of A356/Al2O3 composite fabricated by infiltration method

    Science.gov (United States)

    Yu, Seung-Baek; Jeon, Kyung-Soo; Kim, Mok-Soon; Lee, Jeung-Keun; Ryu, Kwan-Ho

    2017-07-01

    The hot deformation behavior of an A356/Al2O3 composite fabricated by the infiltration method was characterized in the temperature range of 300-500 °C and strain rate range of 0.001-1/s using compressive tests. The composite consists of an Al-Si based matrix and nano-sized Al2O3 particulates. A constitutive model was established based on the hyperbolic sine Arrhenius type equation and its hot workability was evaluated by means of processing maps based on Dynamic Material Modeling. The activation energy for hot deformation was calculated to be 223 kJ/mol, which is higher than the activation energy for self-diffusion of pure aluminum (142 kJ/mol). The optimum processing condition for the hot working of the composite was found to exist at 500 °C with a strain rate of 1/s, where a dynamic recrystallized microstructure was observed and the maximum efficiency was exhibited in the processing map. Voids were frequently detected at 500 °C with lower strain rates, deteriorating the workability of the composite.

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

    Energy Technology Data Exchange (ETDEWEB)

    Li Wen [Dept. of Mechanical Engineering, Changchun University (China); Dept. of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta (Canada); Wang, Y.; Li, D.Y. [Dept. of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta (Canada)

    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. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Effect of electropulsing on deformation behavior, texture and microstructure of 5A02 aluminum alloy during uniaxial tension

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Cong; Li, Ning, E-mail: hslining@mail.hust.edu.cn; Jiang, Huawen; Wang, Duzhen; Liu, Lin

    2015-06-25

    The effect of electropulsing on the deformation behavior, texture and microstructure of 5A02 aluminum alloy was investigated through uniaxial tension, electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). The Portevin-Le Chatelier (PLC) effect reflected as the serrated characteristic in stress–strain curves, became conspicuous firstly but then disappeared with further increase of electropulsing intensity. The texture analysis exhibited that the electropulsing causes an increase of Cube texture, accompanied with a reduction of S texture. Microstructure characterization revealed a transition of slipping mode from planar slip to wave slip with increasing electropulsing intensity. The temperature rise induced by electropulsing, together with the influence of solute atoms, was proposed to rationalize the present phenomena in detail.

  18. Effects of Severe Plastic Deformation and Heat Treatment on Transformation Behavior of Explosively Welded Duplex TiNi-TiNi

    Institute of Scientific and Technical Information of China (English)

    Li Juntao; Zheng Yanjun; Cui Lishan

    2007-01-01

    The effects of severe plastic deformation and heat treatment on the transformation behavior of explosively welded duplex TiNi-TiNi shape memory alloys (SMAs) were investigated by differential scanning calorimeter (DSC) measurements. The explosively welded duplex TiNi-TiNi plate of 0.7 mm thickness was cold-rolled at room temperature to a 60% reduction in thickness and then annealed at different temperatures for different durations. The results showed that low temperature (623-723K) heat-treatment led to the crystallization of the amorphous region, and re-crystallization occurred in the specimens annealed at higher temperatures (over 873 K). Research indicated that the change of martensitic transformation temperature is due to the change of internal stresses with increasing heat treatment temperature. The change of annealing time also led to a change in martensitic transformation temperature, which was associated with the precipitation and decomposition of Ti3Ni4 in TiNi-1.

  19. Microstructure, elastic deformation behavior and mechanical properties of biomedical β-type titanium alloy thin-tube used for stents.

    Science.gov (United States)

    Tian, Yuxing; Yu, Zhentao; Ong, Chun Yee Aaron; Kent, Damon; Wang, Gui

    2015-05-01

    Cold-deformability and mechanical compatibility of the biomedical β-type titanium alloy are the foremost considerations for their application in stents, because the lower ductility restricts the cold-forming of thin-tube and unsatisfactory mechanical performance causes a failed tissue repair. In this paper, β-type titanium alloy (Ti-25Nb-3Zr-3Mo-2Sn, wt%) thin-tube fabricated by routine cold rolling is reported for the first time, and its elastic behavior and mechanical properties are discussed for the various microstructures. The as cold-rolled tube exhibits nonlinear elastic behavior with large recoverable strain of 2.3%. After annealing and aging, a nonlinear elasticity, considered as the intermediate stage between "double yielding" and normal linear elasticity, is attributable to a moderate precipitation of α phase. Quantitive relationships are established between volume fraction of α phase (Vα) and elastic modulus, strength as well as maximal recoverable strain (εmax-R), where the εmax-R of above 2.0% corresponds to the Vα range of 3-10%. It is considered that the "mechanical" stabilization of the (α+β) microstructure is a possible elastic mechanism for explaining the nonlinear elastic behavior.

  20. Mechanical Deformation Behavior of Sn-Ag-Cu Solders with Minor Addition of 0.05 wt.% Ni

    Science.gov (United States)

    Hammad, A. E.; El-Taher, A. M.

    2014-11-01

    The aim of the present work is to develop a comparative evaluation of the microstructural and mechanical deformation behavior of Sn-Ag-Cu (SAC) solders with the minor addition of 0.05 wt.% Ni. Test results showed that, by adding 0.05Ni element into SAC solders, generated mainly small rod-shaped (Cu,Ni)6Sn5 intermetallic compounds (IMCs) inside the β-Sn phase. Moreover, increasing the Ag content and adding Ni could result in the change of the shape and size of the IMC precipitate. Hence, a significant improvement is observed in the mechanical properties of SAC solders with increasing Ag content and Ni addition. On the other hand, the tensile results of Ni-doped SAC solders showed that both the yield stress and ultimate tensile strengths decrease with increasing temperature and with decreasing strain rate. This behavior was attributed to the competing effects of work hardening and dynamic recovery processes. The Sn-2.0Ag-0.5Cu-0.05Ni solder displayed the highest mechanical properties due to the formation of hard (Cu,Ni)6Sn5 IMCs. Based on the obtained stress exponents and activation energies, it is suggested that the dominant deformation mechanism in SAC (205)-, SAC (0505)- and SAC (0505)-0.05Ni solders is pipe diffusion, and lattice self-diffusion in SAC (205)-0.05Ni solder. In view of these results, the Sn-2.0Ag-0.5Cu-0.05Ni alloy is a more reliable solder alloy with improved properties compared with other solder alloys tested in the present work.

  1. Effect of heat treatment on tensile and fatigue deformation behavior of extruded Al-12 wt%Si alloy

    Science.gov (United States)

    Ham, Gi-Su; Baek, Min-Seok; Kim, Jong-Ho; Lee, Si-Woo; Lee, Kee-Ahn

    2017-01-01

    This study investigated the effect of heat treatment on tensile and high-cycle fatigue deformation behavior of extruded Al-12 wt%Si alloy. The material used in this study was extruded at a ratio of 17.7: 1 through extrusion process. To identify the effects of heat treatment, T6 heat treatment (515 °C/1 h, water quenching, and then 175 °C/10 h) was performed. Microstructural observation identified Si phases aligned in the extrusion direction in both extruded alloy (F) and heat treated alloy (T6). The average grain size of F alloy was 8.15 °C, and that of T6 alloy was 8.22 °C. Both alloys were composed of Al matrix, Si, Al2Cu, Al3Ni and AlFeSi phases. As T6 heat treatment was applied, Al2Cu phases became more finely and evenly distributed. Tensile results confirmed that yield strength increased from 119.0 MPa to 329.0 MPa, ultimate tensile strength increased from 226.8 MPa to 391.4 MPa, and the elongation decreased from 16.1% to 5.0% as T6 heat treatment was applied. High-cycle fatigue results represented F alloy's fatigue limit as 185 MPa and T6 alloy's fatigue limit as 275 MPa, indicating that high-cycle fatigue properties increased significantly as heat treatment was conducted. Through tensile and fatigue fracture surface analysis, this study considered the deformation behaviors of extruded and heat treated Al-Si alloys in relation to their microstructures.

  2. High-Temperature Deformation Behavior of a Ti-6Al-7Nb Alloy in Dual-Phase (α + β) and Single-Phase (β) Regions

    Science.gov (United States)

    Pilehva, F.; Zarei-Hanzaki, A.; Moemeni, S.; Khalesian, A. R.

    2016-01-01

    The present study aimed to characterizing the microstructure evolution of a Ti-6Al-7Nb biomedical type titanium alloy during hot working through hot compression tests. The hot deformation cycles were conducted under the strain rate of 0.0025, 0.025, and 0.25 s-1 in the temperature range of 850-1150 °C where both dual-phase (α + β) and single-phase (β) regions could be accessible. The flow stress behavior of the material for the entire deformation regime was interpreted via microstructural observations. The results indicated that in the single-phase β region (1050-1150 °C), the dynamically recrystallized (DRX) grains were formed at the deformed and elongated beta grain boundaries as a necklace-like structure. The variations in the dynamically recrystallized grain size were determined to follow the Zener-Hollomon relationship where DRX grain size was decreased by reducing the temperature and increasing the strain rate. The alloy deformation characteristics in α + β region were somewhat different. During deformation in the upper α + β temperature range (e.g., 1000 °C), the β phase would accommodate most of the deformation, while α regions remained undeformed. In the lower α + β temperature range (e.g., 850-950 °C), the kinking/bending of α lamellae as well as the subsequent globularization of α layers were postulated to be responsible for the observed flow softening behavior.

  3. A Study on the Hot Deformation Behavior of 47Zr-45Ti-5Al-3V Alloy with Initial Lamellar α Structure

    Science.gov (United States)

    Tan, Yuanbiao; Ji, Liyuan; Duan, Jingli; Liu, Wenchang; Zhang, Jingwu; Liu, Riping

    2016-09-01

    The hot deformation behavior of the 47Zr-45Ti-5Al-3V (wt pct) alloy with initial lamellar α structure was investigated by compression tests in the temperature range of 823 K to 1073 K (550 °C to 800 °C) and strain rate range of 10-3 to 100 s-1. In the α + β phase field, the flow curves exhibited a continuous flow softening. The extent of flow softening first decreased with increasing strain rate from 10-3 to 10-1 s-1, and then increased with further increasing strain rate to 100 s-1. In the single β phase field, the flow curves exhibited a pronounced stress drop at the very beginning of deformation at low temperatures and high strain rates. The magnitude of the stress drop increased with decreasing deformation temperature and increasing strain rate. At higher temperatures and lower strain rates, the flow curves exhibited typical characteristics of dynamic recrystallization. A hyperbolic-sine Arrhenius-type equation was used to characterize the dependence of the flow stress on deformation temperature and strain rate. The activation energy for deformation at different strains was calculated. In the α + β phase field, the activation energy for deformation increased from 333 to 355 kJ/mol with increasing strain, and then decreased to 312 kJ/mol. In the single β phase, the activation energy for deformation decreased from 169 to 136 kJ/mol with increasing strain.

  4. A Study on the Hot Deformation Behavior of 47Zr-45Ti-5Al-3V Alloy with Initial Lamellar α Structure

    Science.gov (United States)

    Tan, Yuanbiao; Ji, Liyuan; Duan, Jingli; Liu, Wenchang; Zhang, Jingwu; Liu, Riping

    2016-12-01

    The hot deformation behavior of the 47Zr-45Ti-5Al-3V (wt pct) alloy with initial lamellar α structure was investigated by compression tests in the temperature range of 823 K to 1073 K (550 °C to 800 °C) and strain rate range of 10-3 to 100 s-1. In the α + β phase field, the flow curves exhibited a continuous flow softening. The extent of flow softening first decreased with increasing strain rate from 10-3 to 10-1 s-1, and then increased with further increasing strain rate to 100 s-1. In the single β phase field, the flow curves exhibited a pronounced stress drop at the very beginning of deformation at low temperatures and high strain rates. The magnitude of the stress drop increased with decreasing deformation temperature and increasing strain rate. At higher temperatures and lower strain rates, the flow curves exhibited typical characteristics of dynamic recrystallization. A hyperbolic-sine Arrhenius-type equation was used to characterize the dependence of the flow stress on deformation temperature and strain rate. The activation energy for deformation at different strains was calculated. In the α + β phase field, the activation energy for deformation increased from 333 to 355 kJ/mol with increasing strain, and then decreased to 312 kJ/mol. In the single β phase, the activation energy for deformation decreased from 169 to 136 kJ/mol with increasing strain.

  5. Hot deformation behavior of 51.1Zr–40.2Ti–4.5Al–4.2V alloy in the single β phase field

    Directory of Open Access Journals (Sweden)

    Jingli Duan

    2015-02-01

    Full Text Available The hot deformation behavior of a newly developed 51.1Zr–40.2Ti–4.5Al–4.2 V alloy was investigated by compression tests in the deformation temperature range from 800 to 1050 °C and strain rate range from 10−3 to 100 s−1. At low temperatures and high strain rates, the flow curves exhibited a pronounced stress drop at the very beginning of deformation, followed by a slow decrease in flow stress with increasing strain. The magnitude of the stress drop increased with decreasing deformation temperature and increasing strain rate. At high temperatures and low strain rates, the flow curves exhibited typical characteristics of dynamic recrystallization. A hyperbolic-sine Arrhenius-type equation was used to characterize the dependences of the flow stress on deformation temperature and strain rate. The activation energy for hot deformation decreased slightly with increasing strain and then tended to be a constant value. A microstructural mechanism map was presented to help visualize the microstructure of this alloy under different deformation conditions.

  6. Strain rate dependent deformation and failure behavior of laser welded DP780 steel joint under dynamic tensile loading

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yang, E-mail: liuyang@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China); Dong, Danyang, E-mail: dongdanyang@mail.neu.edu.cn [College of Science, Northeastern University, Shenyang 110819 (China); Wang, Lei, E-mail: wanglei@mail.neu.edu.cn [Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819 (China); Chu, Xi, E-mail: chuxi.ok@163.com [College of Science, Northeastern University, Shenyang 110819 (China); Wang, Pengfei, E-mail: wpf1963871400@163.com [College of Science, Northeastern University, Shenyang 110819 (China); Jin, Mengmeng, E-mail: 24401878@163.com [College of Science, Northeastern University, Shenyang 110819 (China)

    2015-03-11

    Laser welded DP steel joints are used widely in the automotive industry for weight reduction. Understanding the deformation and fracture behavior of the base metal (BM) and its welded joint (WJ), especially at high strain rates, is critical for the design of vehicle structures. This paper is concerned with the effects of strain rate on the tensile properties, deformation and fracture behavior of the laser welded DP780 steel joint. Quasi-static and dynamic tensile tests were performed on the WJ and BM of the DP780 steel using an electromechanical universal testing machine and a high-speed tensile testing machine over a wide range of strain rate (0.0001–1142 s{sup −1}). The microstructure change and microhardness distribution of the DP780 steel after laser welding were examined. Digital image correlation (DIC) and high-speed photography were employed for the strain measurement of the DP780 WJ during dynamic tensile tests. The DP780 WJ is a heterogeneous structure with hardening in fusion zone (FZ) and inner heat-affected zone (HAZ), and softening in outer HAZ. The DP780 BM and WJ exhibit positive strain rate dependence on the YS and UTS, which is smaller at lower strain rates and becomes larger with increasing strain rate, while ductility in terms of total elongation (TE) tends to increase under dynamic loading. Laser welding leads to an overall reduction in the ductility of the DP780 steel. However, the WJ exhibits a similar changing trend of the ductility to that of the BM with respect to the strain rate over the whole strain rate range. As for the DP780 WJ, the distance of tensile failure location from the weld centerline decreases with increasing strain rate. The typical ductile failure characteristics of the DP780 BM and WJ do not change with increasing strain rate. DIC measurements reveal that the strain localization starts even before the maximum load is attained in the DP780 WJ and gradual transition from uniform strains to severely localized strains

  7. High temperature deformation behavior, thermal stability and irradiation performance in Grade 92 steel

    Science.gov (United States)

    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

  8. Deformation Behaviors of HIPped Foil Compared with Those of Sheet Titanium Alloys

    Science.gov (United States)

    Castelli, Michael G.

    1999-01-01

    Micromechanics-based modeling of composite material behaviors requires an accurate assessment of the constituent properties and behaviors. For the specific case of continuous-fiber-reinforced metal matrix composites (MMC's) manufactured from a foil/fiber/foil process, much emphasis has been placed on characterizing foil-based matrix materials that have been fabricated in the same way as the composite. Such materials are believed to yield mechanical properties and behaviors that are representative of the matrix constituent within the composite (in situ matrix). Therefore, these materials are desired for micromechanics modeling input. Unfortunately, such foils are extremely expensive to fabricate and procure because of the labor-intensive rolling process needed to produce them. As a potential solution to this problem that would maintain appropriately representative in situ properties, the matrix constituent could be characterized with sheet-based materials, which are considerably less expensive to manufacture than foils, are more readily procured, and result in fewer plies to obtain a desired panel thickness. The critical question is, however, does the consolidated sheet material exhibit the same properties and behaviors as do the consolidated foils? Researchers at NASA Lewis Research Center's Life Prediction Branch completed a detailed experimental investigation to answer this question for three titanium alloys commonly used in metal matrix composite form.

  9. Hot Deformation Behavior of GH738 for A-USC Turbine Blades

    Institute of Scientific and Technical Information of China (English)

    Li WANG; Gang YANG; Ting LEI; Shu-biao YIN; Lu WANG

    2015-01-01

    The hot deformation characteristics of GH738 superalloy over the temperature range of 1 000 °C to 1 200 °C and strain range of 0.01 s−1to 10.0 s−1under a strain of 1.0 s−1 were investigated through hot compression tests with a Gleeble-1500 simulation machine. The lfow stress reached peak value before lfow softening occurred. The average apparent activation energy (Q) of GH738 was calculated to be 430 kJ/mol, and the stress index (n) is approximately 4.08. The processing map was developed based on lfow stress data and dynamic materials model (DMM). The map shows a dynamic recrystallization (DRX) domain in 1 050 °C to 1 150 °C and 0.01 s−1 to 1.0 s−1 strain rate range with a peak efifciency of 45%, which is considered to be the optimum region for hot working. Moreover, the materials undergo lfow instability in the temperature range of 1 000 °C to 1 050 °C and strain range of 1.0 s−1to 10.0 s−1, and adiabatic shear bands can be observed in this domain.

  10. Deformation behavior of FRP-metal composites locally reinforced with carbon fibers

    Science.gov (United States)

    Scholze, M.; Kolonko, A.; Lindner, T.; Lampke, T.; Helbig, F.

    2016-03-01

    This study investigates variations of hybrid laminates, consisting of one aluminum sheet and a unidirectional glass fiber (GF) reinforced polyamide 6 (PA6) basic structure with partial carbon fiber (CF) reinforcement. To create these heterogeneous FRP laminates, it is necessary to design and produce semi-finished textile-based products. Moreover, a warp knitting machine in conjunction with a warp thread offset unit was used to generate bionic inspired compounds. By the variation of stacking prior to the consolidation process of the hybrid laminate, an oriented CF reinforcement at the top and middle layer of the FRP is realized. In both cases the GFRP layer prevents contact between the aluminum and carbon fibers. In so doing, the high strength of carbon fibers can be transferred to the hybrid laminate in load directions with an active prevention of contact corrosion. The interface strength between thermoplastic and metal component was improved by a thermal spray coating on the aluminum sheet. Because of the high surface roughness and porosity, mechanical interlock was used to provide high interface strength without bonding agents between both components. The resulting mechanical properties of the hybrid laminates are evaluated by three point bending tests in different load directions. The effect of local fiber orientation and layer positioning on failure and deformation mechanism is additionally investigated by digital image correlation (DIC).

  11. On The Creep Behavior and Deformation Mechanisms Found in an Advanced Polycrystalline Nickel-Base Superalloy at High Temperatures

    Science.gov (United States)

    Deutchman, Hallee Zox

    Polycrystalline Ni-base superalloys are used as turbine disks in the hot section in jet engines, placing them in a high temperature and stress environment. As operating temperatures increase in search of better fuel efficiency, it becomes important to understand how these higher temperatures are affecting mechanical behavior and active deformation mechanisms in the substructure. Not only are operating temperatures increasing, but there is a drive to design next generation alloys in shorter time periods using predictive modeling capabilities. This dissertation focuses on mechanical behavior and active deformation mechanisms found in two different advanced polycrystalline alloy systems, information which will then be used to build advanced predictive models to design the next generation of alloys. The first part of this dissertation discusses the creep behavior and identifying active deformation mechanisms in an advanced polycrystalline Ni-based superalloy (ME3) that is currently in operation, but at higher temperatures and stresses than are experienced in current engines. Monotonic creep tests were run at 700°C and between 655-793MPa at 34MPa increments, on two microstructures (called M1 and M2) produced by different heat treatments. All tests were crept to 0.5% plastic strain. Transient temperature and transient stress tests were used determine activation energy and stress exponents of the M1 microstructure. Constant strain rate tests (at 10-4s-1) were performed on both microstructures as well. Following creep testing, both M1 and M2 microstructures were fully characterized using Scanning Electron Microscopy (SEM) for basic microstructure information, and Scanning Transmission Electron Microscopy (STEM) to determine active deformation mechanism. It was found that in the M1 microstructure, reorder mediated activity (such as discontinuous faulting and microtwinning) is dominant at low stresses (655-724 MPa). Dislocations in the gamma matrix, and overall planar

  12. Spontaneous Fission and alpha -Decay Half-Lives of Superheavy Nuclei in Different Macroscopic Energy Models

    CERN Document Server

    Lojewski, Z; Pomorski, K

    2003-01-01

    Spontaneous fission half-lives (T sub s sub f) of the heaviest nuclei are calculated in the macroscopic-microscopic approach based on the deformed Woods-Saxon potential. Four different models of the macroscopic energy are examined and their influence on the results is discussed. The calculations of (T sub s sub f) are performed within WKB approximation. Multi-dimensional dynamical-programming method (MDP) is applied to minimize the action integral in a 3-dimensional space of deformation parameters describing the nuclear shape (beta sub 2 ,beta sub 4 ,beta sub 6).

  13. Macroscopic Quantum Coherence in Antiferromagnetic Molecular Magnets

    Institute of Scientific and Technical Information of China (English)

    HU Hui; LO Rong; ZHU Jia-Lin; XIONG Jia-Jiong

    2001-01-01

    The macroscopic quantum coherence in a biaxial antiferromagnetic molecular magnet in the presence of magnetic field acting parallel to its hard anisotropy axis is studied within the two-sublattice model. On the basis of instanton technique in the spin-coherent-state path-integral representation, both the rigorous Wentzel-Kramers-Brillouin exponent and pre-exponential factor for the ground-state tunnel splitting are obtained. We find that the quantum fluctuations around the classical paths can not only induce a new quantum phase previously reported by Chiolero and Loss (Phys. Rev. Lett. 80 (1998) 169), but also have great influence on the intensity of the ground-state tunnel splitting. Those features clearly have no analogue in the ferromagnetic molecular magnets. We suggest that they may be the universal behaviors in all antiferromagnetic molecular magnets. The analytical results are complemented by exact diagonalization calculation.

  14. Micro- and macroscopic simulation of periodic metamaterials

    Directory of Open Access Journals (Sweden)

    R. Schuhmann

    2008-05-01

    Full Text Available In order to characterize three-dimensional, left-handed metamaterials (LHM we use electromagnetic field simulations of unit cells. For waves traveling in one of the main directions of the periodic LHM-arrays, the analysis is concentrated on the calculation of global quantities of the unit cells, such as scattering parameters or dispersion diagrams, and a careful interpretation of the results. We show that the concept of equivalent material values – which may be negative in a narrow frequency range – can be validated by large "global" simulations of a wedge structure. We also discuss the limitations of this concept, since in some cases the macroscopic behavior of an LHM cannot be accurately described by equivalent material values.

  15. Macroscopic Quantum Coherence in Antiferromagnetic Molecular Magnets

    Institute of Scientific and Technical Information of China (English)

    HUHui; LURong; 等

    2001-01-01

    The macroscopic quantum coherence in a biaxial antiferromagnetic molecular magnet in the presence of magnetic field acting parallel to its hard anisotropy axis is studied within the two-sublattice model.On the basis of instanton technique in the spin-coherent-state path-integral representation,both the rigorous Wentzel-Kramers-Brillouin exponent and pre-exponential factor for the ground-state tunnel splitting are obtained.We find that the quantum fluctuations around the classical paths can not only induce a new quantum phase previously reported by Chiolero and Loss (Phys.Rev.Lett.80(1998)169),but also have great influence on the intensity of the ground-state tunnel splitting.Those features clearly have no analogue in the ferromagnetic molecular magnets.We suggest that they may be the universal behaviors in all antiferromagnetic molecular magnets.The analytical results are complemented by exact diagonalization calculation.

  16. The quantum interaction of macroscopic objects and gravitons

    Science.gov (United States)

    Piran, Tsvi

    2016-09-01

    Copious production of gravitational radiation requires a compact source that moves relativistically. Such sources are rare and are found only in extreme cases such as the formation of a black hole in either via a gravitational collapse or via a merger. Noncompact, nonrelativistic objects emit gravitational radiation, however, this emission is extremely weak due to very large value of the Planck energy. The quantum nature of gravitons, namely the fact that a single graviton carries energy of order ℏω implies that macroscopic objects whose kinetic energy is less than the Planck energy emit gravitons quantum mechanically, emitting a single graviton at a time. This is a unique situation in which a macroscopic object behaves quantum mechanically. While it is impossible to check experimentally this quantum gravitational effect, it might be possible to carry out analogous electromagnetic experiments that will shed light on this macroscopic quantum mechanical behavior.

  17. Cracking and load-deformation behavior of fiber reinforced concrete: Influence of testing method

    DEFF Research Database (Denmark)

    Paegle, Ieva; Minelli, Fausto; Fischer, Gregor

    2016-01-01

    on the definition of measured and derived parameters, including toughness, elastic properties and strength. This paper discusses a number of test procedures for selected material properties including tension and flexure. A comparative experimental study was carried out using two distinct fiber reinforced...... cementitious composites with strain hardening and strain softening behavior. Digital Image Correlation was utilized in the experimental program to detect and quantify the formation of cracks. Results show that the different test methodologies valuate specific aspects of material performance. The outcome...

  18. Monotonic and Cyclic Bond Behavior of Deformed CFRP Bars in High Strength Concrete

    OpenAIRE

    2016-01-01

    Composite reinforcing bars (rebars) that are used in concrete members with high performance (strength and durability) properties could have beneficial effects on the behavior of these members. This is especially vital when a building is constructed in an aggressive environment, for instance a corrosive environment. Although tension capacity/weight (or volume) ratios in composite rebars (carbon fiber reinforced polymer (CFRP), glass fiber reinforced polymer (GFRP), etc.) are very high when com...

  19. Effect of particle friction and polydispersity on the macroscopic stress–strain relations of granular materials

    NARCIS (Netherlands)

    Göncü, F.; Luding, S.

    2013-01-01

    The macroscopic mechanical behavior of granular materials inherently depends on the properties of particles that compose them. Using the discrete element method, the effect of particle contact friction and polydispersity on the macroscopic stress response of 3D sphere packings is studied. The analyt

  20. Micromechanical modeling of the deformation of HCP metals

    Energy Technology Data Exchange (ETDEWEB)

    Graff, S. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung

    2008-12-04

    Nowadays, intense research is conducted to understand the relation between microstructural features and mechanical properties of hexagonal close-packed (hcp) metals. Due to their hexagonal structure, hcp metals exhibit mechanical properties such as strong anisotropy, which is more pronounced than for construction metals with cubic crystal structure, and tension/compression asymmetry. Deformation mechanisms in hcp metals, dislocation motion on specific slip systems and activation of twinning, are not yet completely understood. The purpose of this work is to link the physical mechanisms developing during deformation of magnesium (Mg) on the microscale with the macroscopic yielding properties of texture Mg samples. It will be shown that the mechanical behavior of hcp metals may be understood and reproduced with the help of a visco-plastic model for crystal plasticity and a phenomenological yield criterion with appropriate hardening behavior. The study of single crystal specimens subjected to channel die compression tests reveals the active slip systems and twinning systems of the material considered. The material anisotropy at mesoscale is reproduced by using adequate critical resolved shear stresses (CRSS) for the considered deformation mechanisms. In order to describe the macroscopic behavior, texture is incorporated into polycrystalline Representative Volume Elements (RVEs) and various mechanical properties of extruded bars and rolled plates can be predicted. For RVEs exhibiting the texture of rolled plates the numerical results reveal the plate's anisotropic yielding and hardening behavior on a mesoscale. In order to extend the modeling possibilities to process simulations and to allow for time-saving simulations of structural behavior, a phenomenological yield surface accounting for anisotropy and tension/compression asymmetry has been established and implemented in a finite element code. Its numerous model parameters are calibrated by an optimization

  1. Macroscopic Theory of Dark Sector

    Directory of Open Access Journals (Sweden)

    Boris E. Meierovich

    2014-01-01

    Full Text Available A simple Lagrangian with squared covariant divergence of a vector field as a kinetic term turned out to be an adequate tool for macroscopic description of the dark sector. The zero-mass field acts as the dark energy. Its energy-momentum tensor is a simple additive to the cosmological constant. Massive fields describe two different forms of dark matter. The space-like massive vector field is attractive. It is responsible for the observed plateau in galaxy rotation curves. The time-like massive field displays repulsive elasticity. In balance with dark energy and ordinary matter it provides a four-parametric diversity of regular solutions of the Einstein equations describing different possible cosmological and oscillating nonsingular scenarios of evolution of the Universe. In particular, the singular big bang turns into a regular inflation-like transition from contraction to expansion with the accelerated expansion at late times. The fine-tuned Friedman-Robertson-Walker singular solution is a particular limiting case at the lower boundary of existence of regular oscillating solutions in the absence of vector fields. The simplicity of the general covariant expression for the energy-momentum tensor allows displaying the main properties of the dark sector analytically. Although the physical nature of dark sector is still unknown, the macroscopic theory can help analyze the role of dark matter in astrophysical phenomena without resorting to artificial model assumptions.

  2. Effects of Prior Aging at 316 deg C in Argon on Inelastic Deformation Behavior of PMR-15 Polymer at 316 deg C : Experiment and Modeling

    Science.gov (United States)

    2009-03-01

    after their original formation and decompose thermally at high temperatures [28,30]. Unsaturated polyesters , epoxies, vinylesters, and polyimides are...the VBOP is 48 selected as a suitable choice of constitutive model to represent the inelastic behavior of the PMR-15 neat resin at 316 ◦C. 7.2 Review ...Schoeppner (Member) date AFIT/GSS/ENY/09-M06 Abstract The inelastic deformation behavior of PMR-15 neat resin , a high-temperature polymer, was investigated at

  3. Influence of inclined twin boundaries on the deformation behavior of Cu micropillars

    Energy Technology Data Exchange (ETDEWEB)

    Imrich, P.J., E-mail: peter.imrich@stud.unileoben.ac.at [Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Jahnstraße 12, 8700 Leoben (Austria); Kirchlechner, C., E-mail: c.kirchlechner@mpie.de [Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf (Germany); Department of Materials Physics, Montanuniversität, Jahnstraße 12, 8700 Leoben (Austria); Dehm, G., E-mail: dehm@mpie.de [Max-Planck-Institut für Eisenforschung, Max-Planck-Straße 1, 40237 Düsseldorf (Germany)

    2015-08-26

    In situ micromechanical compression tests on Cu pillars were performed to evaluate the influence of twin boundaries on the mechanical behavior. The 1 µm sized Cu samples on a Si substrate prepared by focused ion beam milling were either single crystalline or contained 2–5 twin boundaries that were inclined to the compression direction. The strengths of the pillars vary, depending on the crystal orientation, associated twin boundary inclination and orientation of slip systems. Results show, that multiple slip systems are activated in each pillar. However, slip parallel to the twin boundaries prevails due to the long mean free path for dislocation movement.

  4. Comparison of the microstructure, deformation and crack initiation behavior of austenitic stainless steel irradiated in-reactor or with protons

    Energy Technology Data Exchange (ETDEWEB)

    Stephenson, Kale J., E-mail: kalejs@umich.edu; Was, Gary S.

    2015-01-15

    Highlights: • Dislocation loops were the prominent defect, but neutron irradiation caused higher loop density. • Grain boundaries had similar amounts of radiation-induced segregation. • The increment in hardness and yield stress due to irradiation were very similar. • Relative IASCC susceptibility was nearly identical. • The effect of dislocation channel step height on IASCC was similar. - Abstract: The objective of this study was to compare the microstructures, microchemistry, hardening, susceptibility to IASCC initiation, and deformation behavior resulting from proton or reactor irradiation. Two commercial purity and six high purity austenitic stainless steels with various solute element additions were compared. Samples of each alloy were irradiated in the BOR-60 fast reactor at 320 °C to doses between approximately 4 and 12 dpa or by a 3.2 MeV proton beam at 360 °C to a dose of 5.5 dpa. Irradiated microstructures consisted mainly of dislocation loops, which were similar in size but lower in density after proton irradiation. Both irradiation types resulted in the formation of Ni–Si rich precipitates in a high purity alloy with added Si, but several other high purity neutron irradiated alloys showed precipitation that was not observed after proton irradiation, likely due to their higher irradiation dose. Low densities of small voids were observed in several high purity proton irradiated alloys, and even lower densities in neutron irradiated alloys, implying void nucleation was in process. Elemental segregation at grain boundaries was very similar after each irradiation type. Constant extension rate tensile experiments on the alloys in simulated light water reactor environments showed excellent agreement in terms of the relative amounts of intergranular cracking, and an analysis of localized deformation after straining showed a similar response of cracking to surface step height after both irradiation types. Overall, excellent agreement was observed

  5. Quantum correlations of lights in macroscopic environments

    Science.gov (United States)

    Sua, Yong Meng

    This dissertation presents a detailed study in exploring quantum correlations of lights in macroscopic environments. We have explored quantum correlations of single photons, weak coherent states, and polarization-correlated/polarization-entangled photons in macroscopic environments. These included macroscopic mirrors, macroscopic photon number, spatially separated observers, noisy photons source and propagation medium with loss or disturbances. We proposed a measurement scheme for observing quantum correlations and entanglement in the spatial properties of two macroscopic mirrors using single photons spatial compass state. We explored the phase space distribution features of spatial compass states, such as chessboard pattern by using the Wigner function. The displacement and tilt correlations of the two mirrors were manifested through the propensities of the compass states. This technique can be used to extract Einstein-Podolsky-Rosen correlations (EPR) of the two mirrors. We then formulated the discrete-like property of the propensity P b(m,n), which can be used to explore environmental perturbed quantum jumps of the EPR correlations in phase space. With single photons spatial compass state, the variances in position and momentum are much smaller than standard quantum limit when using a Gaussian TEM 00 beam. We observed intrinsic quantum correlations of weak coherent states between two parties through balanced homodyne detection. Our scheme can be used as a supplement to decoy-state BB84 protocol and differential phase-shift QKD protocol. We prepared four types of bipartite correlations +/- cos2(theta1 +/- theta 2) that shared between two parties. We also demonstrated bits correlations between two parties separated by 10 km optical fiber. The bits information will be protected by the large quantum phase fluctuation of weak coherent states, adding another physical layer of security to these protocols for quantum key distribution. Using 10 m of highly nonlinear

  6. Effect of non-isothermal deformation of austenite on ferrite transformation behavior studied by in-situ neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Zengmin, E-mail: shzm@ctgu.edu.cn [College of Materials and Chemical Engineering, China Three Gorges University, Yichang 443002 (China); Tomota, Yo [Graduate School of Science and Engineering, Ibaraki University, 4-12-1 Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan); Harjo, Stefanus; Su, Yuhua [J-PARC Center, Japan Atomic Energy Agency, 2-4 Shirane Shirakata, Tokai, Ibaraki 319-1195 (Japan); Chi, Bo; Pu, Jian [School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Jian, Li, E-mail: lijian@hust.edu.cn [School of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2015-04-17

    The microstructure evolution and phase transformation of high strength 22SiMn2TiB steel during non-isothermal deformation were investigated by using in situ time-of-flight (TOF) neutron diffraction technique. The results indicate that the deformation of austenite promotes pearlite and ferrite transformation while suppresses bainite transformation. Deformation texture forms in austenite and then it influences the evolution of transformation texture. Deformation of austenite brings the changes in lattice parameters of austenite caused by carbon partitioning and elastic strains during the transformation. Volume fraction of the retained austenite decreases with a decreased carbon content as deformation amount increases.

  7. Deformation Behavior in Medium Mn Steel of Nanometer-Sized α' + γ Lamellar Structure

    Science.gov (United States)

    Heo, Yoon-Uk; Kim, Dong Hwi; Heo, Nam Hoe; Hong, Chang Wan; Kim, Sung-Joon

    2016-12-01

    Yielding and work-hardening phenomena in an Fe-10.62Mn-2.84Al-0.17C-0.5Mo steel, which is composed of nanometer-sized lamellae of α' and γ, are described on the basis of the Hall-Petch relations. Unlike the general expectation, yielding in the steel, which consists of lamellae of α' and mechanically stable γ, occurs through the propagation of pileup dislocations from α' to γ. However, when γ is mechanically unstable, yielding occurs through the stress-assisted martensitic transformation (SAMT) within the unstable γ region, resulting in a low YS of about 500 MPa. The overall prominent work-hardening behavior of this steel after yielding is due to the active SAMT, which does not accompany the increase in mobile dislocation density and so causes the high elastic strain rate. The carbon partitioning treatment increases the SAMT starting strength to about 980 MPa, which is caused by the mechanical stabilization of γ. The overall low work-hardening behavior of this case is mainly attributed to the active propagation of pile-up dislocation from α' to γ which causes the high plastic strain rate through the abrupt increase of mobile dislocation density.

  8. Hot Deformation Behavior of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe Alloy in α + β Field

    Directory of Open Access Journals (Sweden)

    Zhaoxin Du

    2015-02-01

    Full Text Available The deformation behavior of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe high strength β titanium alloy is systematically investigated by isothermal compression in α + β field with the deformation temperatures ranging from 1003 K to 1078 K, the strain rates ranging from 0.001 s−1 to 1 s−1 and the height reduction is around 50%. Essentially, the flow stress-strain curve of isothermal compression in α + β field exhibits a flow softening feature when the strain rate is higher than 0.1 s−1 as while it exhibits a steady-state feature as the strain rate is lower than 0.1 s−1. The peak stress increases with a decrease in deformation temperature and the increase of strain rate. The activation energy for deformation in α + β field was calculated and the average activation energy of 271.1 kJ/mol. The microstructure observation reveals that the isothermal deformation in the α + β field of the alloy is mainly controlled by the dynamic recovery mechanism accompanied with the secondary dynamic recrystallizitation of β phase. The α phase shows an obvious pinning effect for the movement of dislocations. During deformation, the α phase was elongated and fragmented.

  9. Study of microstructural evolution, microstructure-mechanical properties correlation and collaborative deformation-transformation behavior of quenching and partitioning (Q and P) steel

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Jing; Yu, Hao, E-mail: yhzhmr@126.com; Wang, Shaoyang; Fan, Yongfei

    2014-02-24

    This paper presents a detailed characterization of the microstructural evolution of quenching and partitioning (Q and P) steel by dilatometer, X-ray diffraction and scanning electron microscopy. Influence of partitioning time on mechanical properties was investigated and the relationship between microstructures and mechanical properties was established. The results indicate that bainite transformation occurs at the preliminary stage of partitioning and the amount is proportional to quenching temperature. Martensite softening, bainite transformation kinetics, amount and stability of retained austenite collaboratively have effects on mechanical properties. The purpose of the EBSD investigation is to study the changes in the microstructure of the Q and P steel during deformation and obtain a better understanding of collaborative deformation-transformation behavior. During deformation, plastic deformation preferentially occurred in the vicinity of ferrite–martensite interfaces and spread to the interior of ferrite grain with strain increasing. Plastic deformation started to occur in martensite after large strain. Furthermore, grain rotation occurred in some austenite grains or divided into subgrains during deformation.

  10. In situ synchrotron high-energy X-ray diffraction study of microscopic deformation behavior of a hard-soft dual phase composite containing phase transforming matrix

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Junsong; Hao, Shijie; Jiang, Daqiang; Huan, Yong; Cui, Lishan; Liu, Yinong; Yang, Hong; Ren, Yang

    2017-05-01

    This study explored a novel intermetallic composite design concept based on the principle of lattice strain matching enabled by the collective atomic load transfer. It investigated the hard-soft microscopic deformation behavior of a Ti3Sn/TiNi eutectic hard-soft dual phase composite by means of in situ synchrotron high-energy X-ray diffraction (HE-XRD) during compression. The composite provides a unique micromechanical system with distinctive deformation behaviors and mechanisms from the two components, with the soft TiNi matrix deforming in full compliance via martensite variant reorientation and the hard Ti3Sn lamellae deforming predominantly by rigid body rotation, producing a crystallographic texture for the TiNi matrix and a preferred alignment for the Ti3Sn lamellae. HE-XRD reveals continued martensite variant reorientation during plastic deformation well beyond the stress plateau of TiNi. The hard and brittle Ti3Sn is also found to produce an exceptionally large elastic strain of 1.95% in the composite. This is attributed to the effect of lattice strain matching between the transformation lattice distortion of the TiNi matrix and the elastic strain of Ti3Sn lamellae. With such unique micromechanic characteristics, the composite exhibits high strength and large ductility.

  11. Abnormal Deformation Behavior of Oxygen-Modified β-Type Ti-29Nb-13Ta-4.6Zr Alloys for Biomedical Applications

    Science.gov (United States)

    Liu, Huihong; Niinomi, Mitsuo; Nakai, Masaaki; Cong, Xin; Cho, Ken; Boehlert, Carl J.; Khademi, Vahid

    2017-01-01

    Oxygen was added to the biomedical β-type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ, mass pct) in order to improve its strength, while keeping its Young's modulus low. Conventionally, with an increase in the oxygen content, an alloy's tensile strength increases, while its tensile elongation-to-failure decreases. However, an abnormal deformation behavior has been reported in the case of oxygen-modified TNTZ alloys in that their strength increases monotonically while their elongation-to-failure initially decreases and then increases with the increase in the oxygen content. In this study, this abnormal tensile deformation behavior of oxygen-modified TNTZ alloys was investigated systematically. A series of TNTZ-(0.1, 0.3, and 0.7 mass pct)O alloy samples was prepared, treated thermomechanically, and finally solution treated; these samples are denoted as 0.1ST, 0.3ST, and 0.7ST, respectively. The main tensile deformation mechanisms in 0.1ST are a deformation-induced α″-martensitic transformation and {332} mechanical twinning. The large elongation-to-failure of 0.1ST is attributable to multiple deformation mechanisms, including the deformation-induced martensitic transformation and mechanical twinning as well as dislocation glide. In both 0.3ST and 0.7ST, dislocation glide is the predominant deformation mode. 0.7ST shows more homogeneous and extensive dislocation glide along with multiple slip systems and a higher frequency of cross slip. As a result, it exhibits a higher work-hardening rate and greater resistance to local stress concentration, both of which contribute to its elongation-to-failure being greater than that of 0.3ST.

  12. Indirect measurement of interfacial melting from macroscopic ice observations.

    Science.gov (United States)

    Saruya, Tomotaka; Kurita, Kei; Rempel, Alan W

    2014-06-01

    Premelted water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state well below the bulk melting temperature and can supply the segregated growth of ice lenses. Using macroscopic measurements of ice-lens initiation position in step-freezing experiments, we infer how the nanometer-scale thicknesses of premelted films depend on temperature depression below bulk melting. The interfacial interactions between ice, liquid, and soda-lime glass particles exhibit a power-law behavior that suggests premelting in our system is dominated by short-range electrostatic forces. Using our inferred film thicknesses as inputs to a simple force-balance model with no adjustable parameters, we obtain good quantitative agreement between numerical predictions and observed ice-lens thickness. Macroscopic observations of lensing behavior have the potential as probes of premelting behavior in other systems.

  13. Macroscopically-Discrete Quantum Cosmology

    CERN Document Server

    Chew, Geoffrey F

    2008-01-01

    To Milne's Lorentz-group-based spacetime and Gelfand-Naimark unitary representations of this group we associate a Fock space of 'cosmological preons'-quantum-theoretic universe constituents. Milne's 'cosmological principle' relies on Lorentz invariance of 'age'--global time. We divide Milne's spacetime into 'slices' of fixed macroscopic width in age, with 'cosmological rays' defined on (hyperbolic) slice boundaries-Fock space attaching only to these exceptional universe ages. Each (fixed-age) preon locates within a 6-dimensional manifold, one of whose 3 'extra' dimensions associates in Dirac sense to a self-adjoint operator that represents preon (continuous) local time, the operator canonically-conjugate thereto representing preon (total) energy. Self-adjoint-operator expectations at any spacetime-slice boundary prescribe throughout the following slice a non-fluctuating 'mundane reality'- electromagnetic and gravitational potentials 'tethered' to current densities of locally-conserved electric charge and ener...

  14. Seismic scanning tunneling macroscope - Theory

    KAUST Repository

    Schuster, Gerard T.

    2012-09-01

    We propose a seismic scanning tunneling macroscope (SSTM) that can detect the presence of sub-wavelength scatterers in the near-field of either the source or the receivers. Analytic formulas for the time reverse mirror (TRM) profile associated with a single scatterer model show that the spatial resolution limit to be, unlike the Abbe limit of λ/2, independent of wavelength and linearly proportional to the source-scatterer separation as long as the point scatterer is in the near-field region; if the sub-wavelength scatterer is a spherical impedance discontinuity then the resolution will also be limited by the radius of the sphere. Therefore, superresolution imaging can be achieved as the scatterer approaches the source. This is analogous to an optical scanning tunneling microscope that has sub-wavelength resolution. Scaled to seismic frequencies, it is theoretically possible to extract 100 Hz information from 20 Hz data by imaging of near-field seismic energy.

  15. Theory of Lattice Strain for Materials Undergoing Plastic Deformation

    Science.gov (United States)

    Karato, S.

    2008-12-01

    Radial x-ray diffraction is used to probe physical properties of materials including elastic and plastic properties. The theory used behind such an practice is the one developed by Singh (1993) in which the relation between lattice strain and elastic constants and macroscopic stress is derived. In this theory, the variation of inferred stress with the crystallographic planes, (hkl), is due to the elastic anisotropy. However, recent experimental studies showed that in many cases, the variation of stress with (hkl) far exceeds the value expected from this theory. I have developed a modified theory to rectify this problem with Singh's theory. In Singh's theory, the stress distribution in a polycrystalline material is treated only either unrelaxed or relaxed state. The role of plastic deformation is included only to the extent that plastic flow influences this stress state. Such an assumption corresponds to a Voigt model behavior, which is not an appropriate model at high temperatures where continuing plastic flow occurs with concurrent microscopic equilibrium, elastic deformation. This is a Maxwell model type behavior, and my model provides a stress analysis in a Maxwell material with anisotropic and non-linear power-law rheology. In this theory, the lattice strain corresponding to an imposed macroscopic strain-rate is calculated by three steps: (i) conversion of macroscopic strain-rate to macroscopic stress, (ii) conversion of macroscopic stress to microscopic stress at individual grains, and (iii) calculation of microscopic strain due to microscopic stress. The first step involves anisotropy in macroscopic viscosity that depends on anisotropy in crystal plasticity and lattice-preferred orientation. The second step involves anisotropic crystal plasticity and finally the third step involves elastic crystal anisotropy. In most cases, the influence of LPO is weak and in such a case, the lattice strain depends on (hkl) due to the anisotropy in both elastic and plastic

  16. Evaluation of microscopic deformation behaviors of metal matrix composite by means of SFC test and acoustic emission (Part I :Effect of loading direction)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Joon Hyun; Kang, Moon Phil [Pusan National University, Pusan (Korea, Republic of)

    1998-11-15

    Metal matrix composites(MMCs) offer significant increase in elastic modulus and strength as well as improve resistance to fatigue initiation, creep and wear. For the successful application of MMC to structure, it is very important to understand micro-failure mechanism of material. However, due to complex deformation behavior intrinsically of bulk composite panel, single fiber composite(SFC) has been successfully used to understand a fundamental mechanism of deformation in MMC. The substantial failure mechanisms of MMC were affected by many factors such as the loading direction, the heat treatment condition, matrix properties and volume fraction. In this study, the microscopic deformation behavior of MMC is investigated for single SiC fiber reinforced aluminium alloy under the different loading direction, that is, longitudinal and transverse loading. Acoustic emission(AE) technique has been also used to detect the signals corresponding to each microscopic deformation behavior under the loading. Special attention is given to AE characteristics associated with interfacial debonding between fiber and matrix under the different leading direction.

  17. Modeling the Hot Deformation Behaviors of As-Extruded 7075 Aluminum Alloy by an Artificial Neural Network with Back-Propagation Algorithm

    Science.gov (United States)

    Quan, Guo-zheng; Zou, Zhen-yu; Wang, Tong; Liu, Bo; Li, Jun-chao

    2017-01-01

    In order to investigate the hot deformation behaviors of as-extruded 7075 aluminum alloy, the isothermal compressive tests were conducted at the temperatures of 573, 623, 673 and 723 K and the strain rates of 0.01, 0.1, 1 and 10 s-1 on a Gleeble 1500 thermo-mechanical simulator. The flow behaviors showing complex characteristics are sensitive to strain, strain rate and temperature. The effects of strain, temperature and strain rate on flow stress were analyzed and dynamic recrystallization (DRX)-type softening characteristics of the flow behaviors with single peak were identified. An artificial neural network (ANN) with back-propagation (BP) algorithm was developed to deal with the complex deformation behavior characteristics based on the experimental data. The performance of ANN model has been evaluated in terms of correlation coefficient (R) and average absolute relative error (AARE). A comparative study on Arrhenius-type constitutive equation and ANN model for as-extruded 7075 aluminum alloy was conducted. Finally, the ANN model was successfully applied to the development of processing map and implanted into finite element simulation. The results have sufficiently articulated that the well-trained ANN model with BP algorithm has excellent capability to deal with the complex flow behaviors of as-extruded 7075 aluminum alloy and has great application potentiality in hot deformation processes.

  18. Monotonic and Cyclic Bond Behavior of Deformed CFRP Bars in High Strength Concrete

    Directory of Open Access Journals (Sweden)

    T. Tibet Akbas

    2016-05-01

    Full Text Available Composite reinforcing bars (rebars that are used in concrete members with high performance (strength and durability properties could have beneficial effects on the behavior of these members. This is especially vital when a building is constructed in an aggressive environment, for instance a corrosive environment. Although tension capacity/weight (or volume ratios in composite rebars (carbon fiber reinforced polymer (CFRP, glass fiber reinforced polymer (GFRP, etc. are very high when compared to steel rebars, major weaknesses in concrete members reinforced with these composite rebars may be the potential consequences of relatively poor bonding capacity. This may even be more crucial when the member is subjected to cyclic loading. Although monotonic bond tests are available in the literature, only limited experimental studies exist on bond characteristics under cyclic loading conditions. In order to fill this gap and propose preliminary design recommendations, 10 specimens of 10-mm-diameter ribbed CFRP rebars embedded in specially designed high strength concrete (f’c = 70 MPa blocks were subjected to monotonic and cyclic pullout tests. The experimental results showed that cyclically loaded CFRP rebars had less bond strength than those companion specimens loaded monotonically.

  19. Deformation behavior of NiAl-based alloys containing iron, cobalt, and hafnium

    Science.gov (United States)

    Pank, D. R.; Koss, D. A.; Nathal, M. V.

    1989-01-01

    The effects of alloying additions on the mechanical properties of the B2 intermetallic NiAl have been investigated in both the melt-spun ribbon and consolidated, bulk form. The study is based on a matrix of NiAl-based alloys with up to 20 at. pct Co and Fe additions and with reduced Al levels in the range of 30-40 at. pct. Characterization of the melt-spun ribbon by optical and scanning electron microscopy indicates a range of microstructures, including single-phase beta, gamma-prime necklace phase surrounding either martensitic or beta grains, and a mixture of equiaxed martensitic and gamma-prime grains. Bend ductility is present in melt-spun and annealed ribbons exhibiting the gamma-prime necklace structure and in a single-phase beta material containing 20 at. pct Fe. The analysis of compressive flow behavior on consolidated, bulk specimens indicates that the single-phase beta alloys exhibit a continuous decrease in yield stress with increasing temperature and profuse microcracking at grain boundaries. In contrast, multiphase (gamma-prime + either martensite or beta) alloys tend to display a peak in flow stress between 600 and 800 K, with little or no signs of microcracking. In general, heat treatments which convert the martensitic grains to beta + gamma-prime result in improved strength at temperatures above 600 K and better resistance to crack initiation.

  20. Influence of dynamic strain aging on tensile deformation behavior of alloy 617

    Energy Technology Data Exchange (ETDEWEB)

    Ekaputra, I. M. W. [Pukyong National University, Busan (Korea, Republic of); Kim, Woo Gon; Park, Jae Young; Kim, Seon Jin; Kim, Eung Seon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-12-15

    To investigate the dynamic strain aging (DSA) behavior of Alloy 617, high-temperature tensile tests were carried out with strain rates variations of 10{sup -}3{sup /}s, 10{sup -4}/s, and 10{sup -5}/s from 24°C to 950°C. Five flow relationships, Hollomon, Ludwik, Swift, Ludwigson, and Voce, were applied to describe the tensile true stress–strain curves, and the DSA region was defined. In describing the tensile curves, Ludwigson's equation was superior to the other equations, and the DSA region was adequately defined by this equation as plateaus at intermediate temperatures from 200°C to 700°C. It was identified that Alloy 617 is dominated by three types of serrations, known as Types D, A+B, and C. The activation energy values for each serration type were obtained by the Arrhenius equation. By using the obtained activation energy values, the serrated yielding map and the DSA mechanism were drawn and manifested. In addition, the relationship between the tensile strength and strain rate at higher temperatures above 700°C was found to be closely related to the amounts of slip lines. In the scanning electron microscope (SEM) fractographs, there was a significant difference at the low, intermediate, and high temperatures, but almost the same to the three strain rates.

  1. Global and local deformation behavior and mechanical properties of individual phases in a quenched and partitioned steel

    Energy Technology Data Exchange (ETDEWEB)

    Diego-Calderón, I. de, E-mail: irenedediego.calderon@imdea.org [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain); De Knijf, D. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Monclús, M.A.; Molina-Aldareguia, J.M.; Sabirov, I. [IMDEA Materials Institute, Calle Eric Kandel 2, Getafe 28906, Madrid (Spain); Föjer, C. [ArcelorMittal Global R& D Gent, Pres. J. F. Kennedylaan 3, B-9060 Zelzate (Belgium); Petrov, R.H. [Department of Materials Science and Engineering, Ghent University, Technologiepark 903, B-9052 Zwijnaarde (Ghent) (Belgium); Department of Materials Science and Engineering, Delft University of Technology, 2628 CD Delft (Netherlands)

    2015-04-10

    Third generation advanced high strength steels produced via quenching and partitioning (Q&P) treatment are receiving increased attention. A 0.25C–3Mn–1.5Si–0.023 Al steel was subjected to Q&P processing (with varying partitioning temperature and time) resulting in the formation of complex multi-phase microstructures. The effect of Q&P parameters on the microstructure and morphology of microconstituents was analyzed. Mechanical properties of the material and of its individual microconstituents were studied via tensile testing and nanoindentation on individual microconstituents, which were identified a priori by electron back-scattered diffraction analysis. Special attention is paid to the effect of the morphology of retained austenite on its transformation stability. In situ tensile tests and digital image correlation analysis were performed to study deformation behavior of the Q&P processed steel at the micro-scale with respect to the local microstructure. The effect of local microstructure and properties of individual phases on the degree of strain partitioning is discussed.

  2. Deformation and Recrystallization Behavior of the Cast Structure in Large Size, High Strength Steel Ingots: Experimentation and Modeling

    Science.gov (United States)

    Chadha, K.; Shahriari, D.; Tremblay, R.; Bhattacharjee, P. P.; Jahazi, M.

    2017-07-01

    Constitutive modeling of the ingot breakdown process of large size ingots of high strength steel was carried out through comprehensive thermomechanical processing using Gleeble 3800® thermomechanical simulator, finite element modeling (FEM), optical and electron back scatter diffraction (EBSD). For this purpose, hot compression tests in the range of 1473 K to 1323 K (1200 °C to 1050 °C) and strain rates of 0.25 to 2 s-1 were carried out. The stress-strain curves describing the deformation behavior of the dendritic microstructure of the cast ingot were analyzed in terms of the Arrhenius and Hansel-Spittel models which were implemented in Forge NxT 1.0® FEM software. The results indicated that the Arrhenius model was more reliable in predicting microstructure evolution of the as-cast structure during ingot breakdown, particularly the occurrence of dynamic recrystallization (DRX) process which was a vital parameter in estimating the optimum loads for forming of large size components. The accuracy and reliability of both models were compared in terms of correlation coefficient (R) and the average absolute relative error (ARRE).

  3. Deformation and Recrystallization Behavior of the Cast Structure in Large Size, High Strength Steel Ingots: Experimentation and Modeling

    Science.gov (United States)

    Chadha, K.; Shahriari, D.; Tremblay, R.; Bhattacharjee, P. P.; Jahazi, M.

    2017-09-01

    Constitutive modeling of the ingot breakdown process of large size ingots of high strength steel was carried out through comprehensive thermomechanical processing using Gleeble 3800® thermomechanical simulator, finite element modeling (FEM), optical and electron back scatter diffraction (EBSD). For this purpose, hot compression tests in the range of 1473 K to 1323 K (1200 °C to 1050 °C) and strain rates of 0.25 to 2 s-1 were carried out. The stress-strain curves describing the deformation behavior of the dendritic microstructure of the cast ingot were analyzed in terms of the Arrhenius and Hansel-Spittel models which were implemented in Forge NxT 1.0® FEM software. The results indicated that the Arrhenius model was more reliable in predicting microstructure evolution of the as-cast structure during ingot breakdown, particularly the occurrence of dynamic recrystallization (DRX) process which was a vital parameter in estimating the optimum loads for forming of large size components. The accuracy and reliability of both models were compared in terms of correlation coefficient (R) and the average absolute relative error (ARRE).

  4. Prediction of the Hot Compressive Deformation Behavior for Superalloy Nimonic 80A by BP-ANN Model

    Directory of Open Access Journals (Sweden)

    Guo-zheng Quan

    2016-02-01

    Full Text Available In order to predict hot deformation behavior of superalloy nimonic 80A, a back-propagational artificial neural network (BP-ANN and strain-dependent Arrhenius-type model were established based on the experimental data from isothermal compression tests on a Gleeble-3500 thermo-mechanical simulator at temperatures ranging of 1050–1250 °C, strain rates ranging of 0.01–10.0 s−1. A comparison on a BP-ANN model and modified Arrhenius-type constitutive equation has been implemented in terms of statistical parameters, involving mean value of relative (μ, standard deviation (w, correlation coefficient (R and average absolute relative error (AARE. The μ -value and w -value of the improved Arrhenius-type model are 3.0012% and 2.0533%, respectively, while their values of the BP-ANN model are 0.0714% and 0.2564%, respectively. Meanwhile, the R-value and ARRE-value for the improved Arrhenius-type model are 0.9899 and 3.06%, while their values for the BP-ANN model are 0.9998 and 1.20%. The results indicate that the BP-ANN model can accurately track the experimental data and show a good generalization capability to predict complex flow behavior. Then, a 3D continuous interaction space for temperature, strain rate, strain and stress was constructed based on the expanded data predicted by a well-trained BP-ANN model. The developed 3D continuous space for hot working parameters articulates the intrinsic relationships of superalloy nimonic 80A.

  5. Searching for the nanoscopic–macroscopic boundary

    Energy Technology Data Exchange (ETDEWEB)

    Velásquez, E.A. [GICM and GES Groups, Instituto de Física-FCEN, Universidad de Antioquia UdeA, Calle 70 No. 52-21 Medellín (Colombia); Grupo de Investigación en Modelamiento y Simulación Computacional, Universidad de San Buenaventura Sec. Medellín, A.A. 5222, Medellín (Colombia); Altbir, D. [Departamento de Física, Universidad de Santiago de Chile (USACH), CEDENNA, Santiago (Chile); Mazo-Zuluaga, J. [GICM and GES Groups, Instituto de Física-FCEN, Universidad de Antioquia UdeA, Calle 70 No. 52-21 Medellín (Colombia); Duque, L.F. [GICM and GES Groups, Instituto de Física-FCEN, Universidad de Antioquia UdeA, Calle 70 No. 52-21 Medellín (Colombia); Grupo de Física Teórica, Aplicada y Didáctica, Facultad de Ciencias Exactas y Aplicadas Instituto Tecnológico Metropolitano, Medellín (Colombia); Mejía-López, J., E-mail: jmejia@puc.cl [Facultad de Física, Pontificia Universidad Católica de Chile, CEDENNA, Santiago (Chile)

    2013-12-15

    Several studies have focused on the size-dependent properties of elements, looking for a unique definition of the nanoscopic–macroscopic boundary. By using a novel approach consisting of an energy variational method combined with a quantum Heisenberg model, here we address the size at which the ordering temperature of a magnetic nanoparticle reaches its bulk value. We consider samples with sizes in the range 1–500 nm, as well as several geometries and crystalline lattices and observe that, contrarily to what is commonly argued, the nanoscopic-microscopic boundary depends on both factors: shape and crystalline structure. This suggests that the surface-to-volume ratio is not the unique parameter that defines the behavior of a nanometric sample whenever its size increases reaching the bulk dimension. Comparisons reveal very good agreement with experimental evidence with differences less than 2%. Our results have broad implications for practical issues in measurements on systems at the nanometric scale. - Highlights: • A novel quantum-Heisenberg variational energy method is implemented. • The asymptotic behavior toward the thermodynamic limit is explored. • An important dependence of the nano-bulk boundary on the geometry is found. • And also an important dependence on the crystalline lattice. • We obtain a very good agreement with experimental evidence with differences <2%.

  6. Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network.

    Science.gov (United States)

    Shakiba, Mohammad; Parson, Nick; Chen, X-Grant

    2016-06-30

    The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002-0.31 wt %) was investigated by uniaxial compression tests conducted at different temperatures (400 °C-550 °C) and strain rates (0.01-10 s(-1)). The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN) model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress.

  7. Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Mohammad Shakiba

    2016-06-01

    Full Text Available The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002–0.31 wt % was investigated by uniaxial compression tests conducted at different temperatures (400 °C–550 °C and strain rates (0.01–10 s−1. The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress.

  8. THE MODEL OF PREVENTION OF VANDAL BEHAVIOR PROVIDED BY THE DEFORMATIONS AND DESTRUCTIONS OF VALUABLE SPHERE OF YOUTH

    Directory of Open Access Journals (Sweden)

    Irina V. Vorobyeva

    2015-01-01

    Full Text Available The aim of the present article is to discuss current opportunities for prevention of vandal behavior of young people, taking into account the structural features of valuable sphere of teenagers and young men. Methods. Methods involve psychognostic techniques such as an axiological questionnaire by S.Schwarz, a questionnaire «Motives of vandal behaviour» by I. V. Vorobyeva, O. V. Kruzhkova, S. A. Ostrikova; method of theoretical modelling. Results. Vandalism is described as a fairly common phenomenon among young people, which may be the result not only of deviant orientation of the individual, but also the result of a mismatch of individual values of teenager or young man and imposed by society requirements for his value orientations. 832 teenagers took part in the complex psychological studies. The following four different groups of respondents have been identified and studied: – with an agreed system of prosocial value orientations; – respondents with a mismatched (deformed system of values; – respondents with a destructive (antagonistic system of value orientations; – respondents with agreed antisocial system of value orientations. The model of prevention of vandalism among young people is developed on the basis of the psychological characteristics of these groups and the description of the genesis and causes of vandal behavior with following applying the method of theoretical modeling. This model is based on the principles of accounting axiological aspects of regulation of activity, consideration of personal values as a dynamic system, taking into account the degree of stability of the system of individual value orientations, differentiation and depth of the psychological impact of variation in the choice of forms and methods of psychological influence. The recommendations are proposed; the most appropriate psychological work aspects with each of the groups of respondents are described. Scientific novelty. The proposed authors

  9. Macroscopic theory of dark sector

    CERN Document Server

    Meierovich, Boris E

    2013-01-01

    A simple Lagrangian with squared covariant divergence of a vector field as a kinetic term turned out an adequate tool for macroscopic description of the dark sector. The zero-mass field acts as the dark energy. Its energy-momentum tensor is a simple additive to the cosmological constant. Massive fields {\\phi}_{I} with {\\phi}^{K}{\\phi}_{K}0 describe two different forms of dark matter. The space-like ({\\phi}^{K}{\\phi}_{K}0) massive field displays repulsive elasticity. In balance with dark energy and ordinary matter it provides a four parametric diversity of regular solutions of the Einstein equations describing different possible cosmological and oscillating non-singular scenarios of evolution of the universe. In particular, the singular big bang turns into a regular inflation-like transition from contraction to expansion with the accelerate expansion at late times. The fine-tuned Friedman-Robertson-Walker singular solution is a particular limiting case at the boundary of existence of regular oscillating soluti...

  10. MACROSCOPIC DIVERSITY FOR CDMA MOBILE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Pei Xiaoyan; Hu Jiandong

    2002-01-01

    A novel system of macroscopic diversity with voting rule in CDMA cellular system is suggested in order to raise the coverage and quality of service of CDMA mobile communication system. The estimation of the impact of macroscopic diversity on performance of CDMA cellular system is analyzed and investigated.

  11. MACROSCOPIC DIVERSITY FOR CDMA MOBILE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    PeiXiaoyan; HuJiandong

    2002-01-01

    A novel system of macroscopic diversity with voting rule in CDMA cellular system is suggested in order to raise the coverage and quality of service of CDMA mobile communication system.The estimation of the impact of macroscopic diversity on performance of CDMA cellular system is analyzed and investigated.

  12. Dynamic behavior and microstructural evolution during moderate to high strain rate hot deformation of a Fe-Ni-Cr alloy (alloy 800H)

    Science.gov (United States)

    Cao, Yu; Di, Hongshuang; Zhang, Jiecen; Yang, Yaohua

    2015-01-01

    The objective of the study is to fundamentally understand the dynamic behavior of alloy 800H at moderate to high strain rate using hot compression tests and propose nucleation mechanism associated with dynamic crystallization (DRX). We firstly investigated the dynamic behavior of alloy 800H with industrial scale strain rates using hot compression tests and adiabatic correction was performed to correct as-measured flow curves. Secondly, a Johnson-Cook model was established by using the corrected data and could give a precise prediction of elevated temperature flow stress for the studied alloy. Finally, the nucleation mechanism of DRX grains at high strain rates was studied. The results showed that the predominant nucleation mechanism for DRX is the formation of "bulge" at parent grain boundary. Additionally, the fragmentation of original grain at low deformation temperatures and the twinning near the bulged regions at high deformation temperatures also accelerate the DRX process.

  13. Macro-scale deformation behavior and characterization of deformation mechanisms below µm-scale in experimentally deformed Boom Clay by using the combination of triaxial compression, X-ray µ-CT imaging, DIC, BIB cross sectioning, and SEM

    Science.gov (United States)

    Oelker, Anne; Desbois, Guillaume; Urai, Janos L.; Bésuelle, Pierre; Viggiani, Gioacchino; Levasseur, Séverine

    2017-04-01

    Boom Clay is one formation being studied in Belgium as a potential host rock for deep geological disposal of radioactive waste. This poorly indurated clay presents in its natural state favorable properties against the migration of radionuclides: low permeability, low solute diffusion rates, good retention and sorption capacity for many radionuclides and good self-sealing capacity. During construction of disposal galleries, stress redistribution will lead to perturbation of the clay and the formation around galleries of the so-called "Excavation disturbed Zone" (EdZ). The study of deformation mechanisms and evolution of Boom Clay properties at macro but also micro scale allows to assess in a more mechanistic way the evolution of Boom Clay properties in this EdZ. In this work, we show microstructural investigations of Boom Clay deformed in undrained triaxial compression by linking conventional stress/strain curves with Digital Image Correlation (DIC) and scanning electron microscopy (SEM) imaging of broad-ion-beam (BIB) milled cross-sections to deduce deformation mechanisms based on microstructures at sub-micron resolution. Two specimens, collected in Mol (Belgium) at the European Underground Laboratories (URL) on HADES level, were analyzed: The major principal stress σ1 was applied parallel as well as perpendicular to the bedding direction with an initial mean normal effective stress of 4.5 MPa and an initial pore water pressure of 2.3 MPa, which are equal to the in-situ values. Linking the resulting DIC-derived maps of incremental strains with the corresponding stress/strain curve give not only information about the moment of the shear band development, but also on the way strain evolves within the specimen throughout the rest. Incremental DIC analysis of X-ray tomographic scans performed during loading tests give a time evolution of the strain field, and subsequently allow to detect strain localization which appears close to the stress peak. Regions with a

  14. Macroscopic Quantum Phenomena from the Correlation, Coupling and Criticality Perspectives

    Science.gov (United States)

    Chou, C. H.; Hu, B. L.; Subaşi, Y.

    2011-12-01

    In this sequel paper we explore how macroscopic quantum phenomena can be measured or understood from the behavior of quantum correlations which exist in a quantum system of many particles or components and how the interaction strengths change with energy or scale, under ordinary situations and when the system is near its critical point. We use the nPI (master) effective action related to the Boltzmann-BBGKY / Schwinger-Dyson hierarchy of equations as a tool for systemizing the contributions of higher order correlation functions to the dynamics of lower order correlation functions. Together with the large N expansion discussed in our first paper [1] we explore 1) the conditions whereby an H-theorem is obtained, which can be viewed as a signifier of the emergence of macroscopic behavior in the system. We give two more examples from past work: 2) the nonequilibrium dynamics of N atoms in an optical lattice under the large Script N (field components), 2PI and second order perturbative expansions, illustrating how N and Script N enter in these three aspects of quantum correlations, coherence and coupling strength. 3) the behavior of an interacting quantum system near its critical point, the effects of quantum and thermal fluctuations and the conditions under which the system manifests infrared dimensional reduction. We also discuss how the effective field theory concept bears on macroscopic quantum phenomena: the running of the coupling parameters with energy or scale imparts a dynamical-dependent and an interaction-sensitive definition of 'macroscopia'.

  15. Microstructure and annealing behavior of a modified 9Cr-1Mo steel after dynamic plastic deformation to different strains

    DEFF Research Database (Denmark)

    Zhang, Zhenbo; Mishin, Oleg; Tao, N.R.;

    2015-01-01

    The microstructure, hardness and tensile properties of a modified 9Cr-1Mo steel processed by dynamic plastic deformation (DPD) to different strains (0.5 and 2.3) have been investigated in the as-deformed and annealed conditions. It is found that significant structural refinement and a high level...... of strength can be achieved by DPD to a strain of 2.3, and that the microstructure at this strain contains a large fraction of high angle boundaries. The ductility of the DPD processed steel is however low. Considerable structural coarsening of the deformed microstructure without pronounced recrystallization...

  16. Hot Deformation Behavior of As-Cast 2101 Grade Lean Duplex Stainless Steel and the Associated Changes in Microstructure and Crystallographic Texture

    Science.gov (United States)

    Patra, Sudipta; Ghosh, Abhijit; Singhal, Lokesh Kumar; Podder, Arijit Saha; Sood, Jagmohan; Kumar, Vinod; Chakrabarti, Debalay

    2016-11-01

    The hot deformation behavior of 2101 grade lean duplex stainless steel (DSS, containing 5 wt pct Mn, 0.2 wt pct N, and 1.4 wt pct Ni) and associated microstructural changes within δ-ferrite and austenite (γ) phases were investigated by hot-compression testing in a GLEEBLE 3500 simulator over a range of deformation temperatures, T def [1073 K to 1373 K (800 °C to 1100 °C)], and applied strains, ɛ (0.25 to 0.80), at a constant true strain rate of 1/s. The microstructural softening inside γ was dictated by discontinuous dynamic recrystallization (DDRX) at a higher T def [1273 K to 1373 K (1000 °C to 1100 °C)], while the same was dictated by continuous dynamic recrystallization (CDRX) at a lower T def (1173 K (900 °C)]. Dynamic recovery (DRV) and CDRX dominated the softening inside δ-ferrite at T def ≥ 1173 K (900 °C). The dynamic recrystallization (DRX) inside δ and γ could not take place upon deformation at 1073 K (800 °C). The average flow stress level increased 2 to 3 times as the T def dropped from 1273 to 1173 K (1000 °C to 900 °C) and finally to 1073 K (800 °C). The average microhardness values taken from δ-ferrite and γ regions of the deformed samples showed a different trend. At T def of 1373 K (1100 °C), microhardness decreased with the increase in strain, while at T def of 1173 K (900 °C), microhardness increased with the increase in strain. The microstructural changes and hardness variation within individual phases of hot-deformed samples are explained in view of the chemical composition of the steel and deformation parameters (T def and ɛ).

  17. Hot Deformation Behavior of As-Cast 2101 Grade Lean Duplex Stainless Steel and the Associated Changes in Microstructure and Crystallographic Texture

    Science.gov (United States)

    Patra, Sudipta; Ghosh, Abhijit; Singhal, Lokesh Kumar; Podder, Arijit Saha; Sood, Jagmohan; Kumar, Vinod; Chakrabarti, Debalay

    2017-01-01

    The hot deformation behavior of 2101 grade lean duplex stainless steel (DSS, containing 5 wt pct Mn, 0.2 wt pct N, and 1.4 wt pct Ni) and associated microstructural changes within δ-ferrite and austenite ( γ) phases were investigated by hot-compression testing in a GLEEBLE 3500 simulator over a range of deformation temperatures, T def [1073 K to 1373 K (800 °C to 1100 °C)], and applied strains, ɛ (0.25 to 0.80), at a constant true strain rate of 1/s. The microstructural softening inside γ was dictated by discontinuous dynamic recrystallization (DDRX) at a higher T def [1273 K to 1373 K (1000 °C to 1100 °C)], while the same was dictated by continuous dynamic recrystallization (CDRX) at a lower T def (1173 K (900 °C)]. Dynamic recovery (DRV) and CDRX dominated the softening inside δ-ferrite at T def ≥ 1173 K (900 °C). The dynamic recrystallization (DRX) inside δ and γ could not take place upon deformation at 1073 K (800 °C). The average flow stress level increased 2 to 3 times as the T def dropped from 1273 to 1173 K (1000 °C to 900 °C) and finally to 1073 K (800 °C). The average microhardness values taken from δ-ferrite and γ regions of the deformed samples showed a different trend. At T def of 1373 K (1100 °C), microhardness decreased with the increase in strain, while at T def of 1173 K (900 °C), microhardness increased with the increase in strain. The microstructural changes and hardness variation within individual phases of hot-deformed samples are explained in view of the chemical composition of the steel and deformation parameters ( T def and ɛ).

  18. Characterization of Deformation Behavior of Individual Grains in Polycrystalline Cu-Al-Mn Superelastic Alloy Using White X-ray Microbeam Diffraction

    Directory of Open Access Journals (Sweden)

    Eui Pyo Kwon

    2015-10-01

    Full Text Available White X-ray microbeam diffraction was applied to investigate the microscopic deformation behavior of individual grains in a Cu-Al-Mn superelastic alloy. Strain/stresses were measured in situ at different positions in several grains having different orientations during a tensile test. The results indicated inhomogeneous stress distribution, both at the granular and intragranular scale. Strain/stress evolution showed reversible phenomena during the superelastic behavior of the tensile sample, probably because of the reversible martensitic transformation. However, strain recovery of the sample was incomplete due to the residual martensite, which results in the formation of local compressive residual stresses at grain boundary regions.

  19. Bending springback behavior related to deformation-induced phase transformations in Ti-12Cr and Ti-29Nb-13Ta-4.6Zr alloys for spinal fixation applications.

    Science.gov (United States)

    Liu, Huihong; Niinomi, Mitsuo; Nakai, Masaaki; Hieda, Junko; Cho, Ken

    2014-06-01

    The springback behavior of Ti-12Cr and Ti-29Nb-13Ta-4.6Zr (TNTZ) during deformation by bending was investigated; and the microstructures of the non-deformed and deformed parts of both alloys were systematically examined to clarify the relationship between microstructure and springback behavior. For the deformed Ti-12Cr alloy, deformation-induced ω-phase transformation occurs in both the areas of compression and tension within the deformed part, which increases the Young׳s modulus. With the deformed TNTZ alloy, deformation-induced ω-phase transformation is observed in the area of compression within the deformed part; while a deformation-induced α″ martensite transformation occurs in the area under tension, which is likely to be associated with the pseudoelasticity of TNTZ. Among these two alloys, Ti-12Cr exhibits a smaller springback and a much greater bending strength when compared with TNTZ; making Ti-12Cr the more advantageous for spinal fixation applications.

  20. Cloud Macroscopic Organization: Order Emerging from Randomness

    Science.gov (United States)

    Yuan, Tianle

    2011-01-01

    Clouds play a central role in many aspects of the climate system and their forms and shapes are remarkably diverse. Appropriate representation of clouds in climate models is a major challenge because cloud processes span at least eight orders of magnitude in spatial scales. Here we show that there exists order in cloud size distribution of low-level clouds, and that it follows a power-law distribution with exponent gamma close to 2. gamma is insensitive to yearly variations in environmental conditions, but has regional variations and land-ocean contrasts. More importantly, we demonstrate this self-organizing behavior of clouds emerges naturally from a complex network model with simple, physical organizing principles: random clumping and merging. We also demonstrate symmetry between clear and cloudy skies in terms of macroscopic organization because of similar fundamental underlying organizing principles. The order in the apparently complex cloud-clear field thus has its root in random local interactions. Studying cloud organization with complex network models is an attractive new approach that has wide applications in climate science. We also propose a concept of cloud statistic mechanics approach. This approach is fully complementary to deterministic models, and the two approaches provide a powerful framework to meet the challenge of representing clouds in our climate models when working in tandem.

  1. Cloud macroscopic organization: order emerging from randomness

    Directory of Open Access Journals (Sweden)

    T. Yuan

    2011-01-01

    Full Text Available Clouds play a central role in many aspects of the climate system and their forms and shapes are remarkably diverse. Appropriate representation of clouds in climate models is a major challenge because cloud processes span at least eight orders of magnitude in spatial scales. Here we show that there exists order in cloud size distribution of low-level clouds and it follows a power-law distribution with exponent γ close to 2. γ is insensitive to yearly variations in environmental conditions, but has regional variations and land-ocean contrasts. More importantly, we demonstrate this self-organizing behavior of clouds emerges naturally from a complex network model with simple, physical organizing principles: random clumping and merging. We also show clear-cloudy sky symmetry in terms of macroscopic organization because of similar fundamental underlying organizing principles. The order in the apparently complex cloud-clear field thus has its root in random simple interactions. Studying cloud organization with complex network models is an attractive new approach that has wide applications in climate science. This approach is fully complementary to deterministic models and the two approaches provide a powerful framework to meet the challenge of representing clouds in our climate models when working in tandem.

  2. Rank distributions: A panoramic macroscopic outlook

    Science.gov (United States)

    Eliazar, Iddo I.; Cohen, Morrel H.

    2014-01-01

    This paper presents a panoramic macroscopic outlook of rank distributions. We establish a general framework for the analysis of rank distributions, which classifies them into five macroscopic "socioeconomic" states: monarchy, oligarchy-feudalism, criticality, socialism-capitalism, and communism. Oligarchy-feudalism is shown to be characterized by discrete macroscopic rank distributions, and socialism-capitalism is shown to be characterized by continuous macroscopic size distributions. Criticality is a transition state between oligarchy-feudalism and socialism-capitalism, which can manifest allometric scaling with multifractal spectra. Monarchy and communism are extreme forms of oligarchy-feudalism and socialism-capitalism, respectively, in which the intrinsic randomness vanishes. The general framework is applied to three different models of rank distributions—top-down, bottom-up, and global—and unveils each model's macroscopic universality and versatility. The global model yields a macroscopic classification of the generalized Zipf law, an omnipresent form of rank distributions observed across the sciences. An amalgamation of the three models establishes a universal rank-distribution explanation for the macroscopic emergence of a prevalent class of continuous size distributions, ones governed by unimodal densities with both Pareto and inverse-Pareto power-law tails.

  3. Strength variation and deformational behavior in anisotropic granitic mylonites under high-temperature and -pressure conditions - An experimental study

    Science.gov (United States)

    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 plastic

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

    Science.gov (United States)

    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.

  5. The hot deformation behavior and microstructure evolution of HA/Mg-3Zn-0.8Zr composites for biomedical application.

    Science.gov (United States)

    Liu, Debao; Liu, Yichi; Zhao, Yue; Huang, Y; Chen, Minfang

    2017-08-01

    The hot deformation behavior of nano-sized hydroxylapatite (HA) reinforced Mg-3Zn-0.8Zr composites were performed by means of Gleeble-1500D thermal simulation machine in a temperature range of 523-673K and a strain rate range of 0.001-1s(-1), and the microstructure evolution during hot compression deformation were also investigated. The results show that the flow stress increases increasing strain rates at a constant temperature, and decreases with increasing deforming temperatures at a constant strain rate. Under the same processing conditions, the flow stresses of the 1HA/Mg-3Zn-0.8Zr specimens are higher than those of the Mg-3Zn-0.8Zr alloy specimens, and the difference is getting closer with increasing deformation temperature. The hot deformation behaviors of Mg-3Zn-0.8Zr and 1HA/Mg-3Zn-0.8Zr can be described by constitutive equation of hyperbolic sine function with the hot deformation activation energy being 124.6kJ/mol and 125.3kJ/mol, respectively. Comparing with Mg-3Zn-0.8Zr alloy, the instability region in the process map of 1HA/Mg-3Zn-0.8Zr expanded to a bigger extent at the same conditions. The optimum process conditions of 1HA/Mg-3Zn-0.8Zr composite is concluded as between the temperature window of 573-623K with a strain rate range of 0.001-0.1s(-1). A higher volume fraction and smaller grain size of dynamic recrystallization (DRX) grains was observed in 1HA/Mg-3Zn-0.8Zr specimens after the hot compression deformation compared with Mg-3Zn-0.8Zr alloy, which was ascribed to the presence of the HA particles that play an important role in particle-stimulated nucleation (PSN) mechanism and can effectively hinder the migration of interfaces. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Microstructure and High Temperature Plastic Deformation Behavior of Al-12Si Based Alloy Fabricated by an Electromagnetic Casting and Stirring Process

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Kyung-Soo; Roh, Heung-Ryeol; Kim, Mok-Soon [Inha University, Incheon (Korea, Republic of); Kim, Jong-Ho; Park, Joon-Pyo [Research Institute of Industrial Science and Technology, Pohang (Korea, Republic of)

    2017-06-15

    An as-received EMC/S (electromagnetic casting and stirring)-processed Al-12Si based alloy billet was homogenized to examine its microstructure and high temperature plastic deformation behavior, using compressive tests over the temperature range from 623 to 743 K and a strain rate range from 1.0×10{sup -3} to 1.0×10{sup 0}s{sup -1}. The results were compared with samples processed by the direct chill casting (DC) method. The fraction of equiaxed structure for the as-received EMC/S billet(41%) was much higher than that of the as-received DC billet(6 %). All true stress – true strain curves acquired from the compressive tests exhibited a peak stress at the initial stage of plastic deformation. Flow stress showed a steady state region after the appearance of peak stress with increasing strain. The peak stress decreased with increasing temperature at a given strain rate and a decreasing strain rate at a given temperature. A constitutive equation was made for each alloy, which could be used to predict the peak stress. A recrystallized grain structure was observed in all the deformed specimens, indicating that dynamic recrystallization is the predominant mechanism during high temperature plastic deformation of both the homogenized EMC/S and DC-processed Al-12Si based alloys.

  7. Influence of alloying and testing conditions on mechanical properties and deformation behavior of 〈100〉 tungsten-based single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Skotnicova, Katerina, E-mail: Katerina.Skotnicova@vsb.cz [VSB – Technical University of Ostrava, Faculty of Metallurgy and Materials Engineering, Department of Regional Materials Science and Technology Centre, Avenue 17 Listopadu 15, 70833 Ostrava-Poruba (Czech Republic); Kirillova, Valentina M.; Ermishkin, Vjacheslav A. [Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Leninski Prospect 49, 119991 Moscow (Russian Federation); Cegan, Tomas; Jurica, Jan; Kraus, Martin [VSB – Technical University of Ostrava, Faculty of Metallurgy and Materials Engineering, Department of Regional Materials Science and Technology Centre, Avenue 17 Listopadu 15, 70833 Ostrava-Poruba (Czech Republic); Burkhanov, Gennadij S. [Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Leninski Prospect 49, 119991 Moscow (Russian Federation)

    2015-06-11

    The results of the pressure testing of mechanical properties of single crystals of pure tungsten and low-alloyed alloys W–2Re and W–1Re–1Mo (wt%) with a crystallographic orientation 〈100〉 which were prepared by plasma-arc melting are summarized. The effect of alloying and the deformation rate on these properties have also been investigated and the fracture surfaces of the individual single crystals have been evaluated with the aid of the photometric method. The differences in the deformation behavior of pure tungsten and W–Re and W–1Mo–Re alloys were observed, which relate to the particularities of rhenium and molybdenum action in the tungsten solid solution. It can be seen from the observed results that tungsten alloying with low rhenium and molybdenum contents decreased all mechanical properties when applying the deformation rate of 0.2 mm/min. The biggest decrease was observed for the offset yield strength value. When testing with the deformation rate of 2 mm/min, the strength limit of the W–2Re alloy increased to 2013 MPa, while R{sub pt0.2} decreased by 33% in comparison with the pure tungsten single crystal. However, the ε{sub r} value remained at the same level ∼30%. In the W–1Re–1Mo single crystal, the R{sub pt0.2} and R{sub mt} values decreased, while ε{sub r} increased slightly.

  8. Cyclic Deformation Behavior of Fe-18Cr-18Mn-0.63N Nickel-Free High-Nitrogen Austenitic Stainless Steel

    Science.gov (United States)

    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.

  9. T23钢的热变形行为%Thermal deformation behavior of T23 steel

    Institute of Scientific and Technical Information of China (English)

    李红英; 巫荣海; 魏冬冬; 李阳华; 龙功名; 王晓峰

    2013-01-01

    The hot deformation behavior and corresponding microstructure of T23 steel were investigated at strain rates ranging from 0. 01 to 5 s-1 and at 1000 - 1250℃ by hot compression test on a Gleeble 1500 thermal-mechanical simulator. True stress-true strain curves were obtained. Processing map was established based on the dynamic material model and flow stress equation was derivated. The results show that both dynamic recovery and dynamic recrystallization occur during hot compression test. The higher the temperature is and the smaller the strain rate is, the more easily the dynamic recrystallization occurs. The processing maps with strain of 0. 5 and 0. 6 present four similar unstable areas, and the distribution of power dissipation factor is similar too. The peak area is 1175 - 1240℃ and 0.03 -0.25 s-1 , corresponding to the peak efficiency of 47. 3% (0.5) and 46. 3% (0.6). In flow stress equation, structure factor A is 5. 23 × 1012 s-1 , stress level parameters a is 0. 01155 Mpa , stress index n is 4.46869, respectively. Deformation activation energy is 368. 65 kJ/mol.%利用Gleeble-1500热模拟机进行热压缩实验,对T23钢在变形速率为0.01 ~5 s-1,变形温度为1000~1250 ℃的热变形行为和组织进行研究.根据实验获得的真应力-真应变曲线,基于动态材料模型建立了热加工图,并推导出流变应力方程.结果表明:T23钢在热压缩过程中存在动态回复和动态再结晶两种软化机制,变形温度越高或变形速率越小,越容易发生动态再结晶.真应变量为0.5和0.6的加工图具有4个类似的失稳区,功率耗散效率因子的分布规律大致相同,峰值区在1175 ~1240℃和0.03~0.25 s-1范围,对应的峰值效率分别为47.3%(0.5)和46.3%(0.6).流变应力方程中,结构因子A、应力水平参数α、应力指数n分别为5.23×1012 s-1、0.01155 MPa-1和4.46869,热变形激活能为368.65 kJ/mol.

  10. Structural mechanisms as revealed by real time mechano optical behavior of polylactic acid films in uni and biaxial deformation and heat setting processes

    Science.gov (United States)

    Ou, Xuesong

    In this study, structural development during PLA film processing was investigated with a new instrumented biaxial stretcher capable of real time monitoring of true stress, true strain and in-plane as well as out-of-plane birefringence under fast deformation rates. The effects of stretching rate and mode on mechano-optical behaviors and correspondent morphology development were investigated. At low deformation levels, a linear regime I associated with orientation of amorphous chains was observed in all modes of deformation. Following regime I, a steeper regime II associated with stress induced crystallization was observed during uniaxial constrained width (UCW) stretching under low rates before birefringence begins to level off in regime III due to finite extensibility of chains. During UCW stretching under high rate, regime I transformed directly into regime III, and this is associated with the formation of a very stable nematic mesophase. Direct transformation from regime I to regime III is observed during simultaneous biaxial (SIM) stretching under all rates. The kinetics of structural changes during heat setting from a pre-oriented state was investigated by rapid tracking of in and out-of-plane birefringence of pre-oriented films with a new instrumented annealing chamber capable of fast sample insertion and removal. Development of birefringence, which reflects overall chain orientation, and associated structural evolution during constrained annealing of extended PLA films were clarified. Structural evolution is determined by the competition between chain relaxation and registration of segments into well oriented nuclei that grow during annealing, leading to formation of a long range network of chains that arrests the chains in their oriented state. At low deformation the temporal evolution of birefringence first involves relaxation followed by a rapid increase associated with crystallization. The initial relaxation disappears with increase in deformation in the

  11. Reliability Assessment of Impact Tensile Testing Apparatus using a Drop-bar Striker for Intermediate Strain-rate Range and Evaluation of Dynamic Deformation Behaviors for a Carbon Steel

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Kyung Oh; Kim, Dae Woong; Shin, Hyung Seop [Andong National Univ., Andong (Korea, Republic of); Park, Lee Ju; Kim, Hyung Won [Agency for Defense Development, Daejeon (Korea, Republic of)

    2016-06-15

    Studies on the deformation behavior of materials subjected to impact loads have been carried out in various fields of engineering and industry. The deformation and fracture of members for these machines/structures are known to correspond to the intermediate strain-rate region. Therefore, for the structural design, it is necessary to consider the dynamic deformation behavior in these intermediate strain-rate ranges. However, there have been few reports with useful data about the deformation and fracture behavior at intermediate strain-rate ranges. Because the intermediate strain-rate region is located between quasi-static and high strain-rate regions, it is difficult to obtain the intermediate strain-rate using conventional reasonable test equipment. To solve this problem, in this study, the measurement reliability of the constructed drop-bar impact tensile test apparatus was established and the dynamic behavior at the intermediate strain-rate range of carbon steels was evaluated by utilizing the apparatus.

  12. Applying quantum mechanics to macroscopic and mesoscopic systems

    CERN Document Server

    T., N Poveda

    2012-01-01

    There exists a paradigm in which Quantum Mechanics is an exclusively developed theory to explain phenomena on a microscopic scale. As the Planck's constant is extremely small, $h\\sim10^{-34}{J.s}$, and as in the relation of de Broglie the wavelength is inversely proportional to the momentum; for a mesoscopic or macroscopic object the Broglie wavelength is very small, and consequently the undulatory behavior of this object is undetectable. In this paper we show that with a particle oscillating around its classical trajectory, the action is an integer multiple of a quantum of action, $S = nh_{o}$. The quantum of action, $h_{o}$, which plays a role equivalent to Planck's constant, is a free parameter that must be determined and depends on the physical system considered. For a mesoscopic and macroscopic system: $h_{o}\\gg h$, this allows us to describe these systems with the formalism of quantum mechanics.

  13. Macroscopic transport by synthetic molecular machines

    NARCIS (Netherlands)

    Berna, J; Leigh, DA; Lubomska, M; Mendoza, SM; Perez, EM; Rudolf, P; Teobaldi, G; Zerbetto, F

    2005-01-01

    Nature uses molecular motors and machines in virtually every significant biological process, but demonstrating that simpler artificial structures operating through the same gross mechanisms can be interfaced with - and perform physical tasks in - the macroscopic world represents a significant hurdle

  14. Rate-dependent deformation of rocks in the brittle regime

    Science.gov (United States)

    Baud, P.; Brantut, N.; Heap, M. J.; Meredith, P. G.

    2013-12-01

    Rate-dependent brittle deformation of rocks, a phenomenon relevant for long-term interseismic phases of deformation, is poorly understood quantitatively. Rate-dependence can arise from chemically-activated, subcritical crack growth, which is known to occur in the presence of aqueous fluids. Here we attempt to establish quantitative links between this small scale process and its macroscopic manifestations. We performed a series of brittle deformation experiments in porous sandstones, in creep (constant stress) and constant strain rate conditions, in order to investigate the relationship between their short- and long-term mechanical behaviors. Elastic wave velocities measurements indicate that the amount of microcracking follows the amount of inelastic strain in a trend which does not depend upon the timescale involved. The comparison of stress-strain curves between constant strain rate and creep tests allows us to define a stress difference between the two, which can be viewed as a difference in energy release rate. We empirically show that the creep strain rates are proportional to an exponential function of this stress difference. We then establish a general method to estimate empirical micromechanical functions relating the applied stresses to mode I stress intensity factors at microcrack tips, and we determine the relationship between creep strain rates and stress intensity factors in our sandstone creep experiments. We finally provide an estimate of the sub-critical crack growth law parameters, and find that they match -within the experimental errors and approximations of the method- the typical values observed in independent single crack tests. Our approach provides a comprehensive and unifying explanation for the origin and the macroscopic manifestation of time-dependent brittle deformation in brittle rocks.

  15. Assessments of macroscopicity for quantum optical states

    DEFF Research Database (Denmark)

    Laghaout, Amine; Neergaard-Nielsen, Jonas Schou; Andersen, Ulrik Lund

    2015-01-01

    With the slow but constant progress in the coherent control of quantum systems, it is now possible to create large quantum superpositions. There has therefore been an increased interest in quantifying any claims of macroscopicity. We attempt here to motivate three criteria which we believe should...... enter in the assessment of macroscopic quantumness: The number of quantum fluctuation photons, the purity of the states, and the ease with which the branches making up the state can be distinguished. © 2014....

  16. Quantum Bell Inequalities from Macroscopic Locality

    CERN Document Server

    Yang, Tzyh Haur; Sheridan, Lana; Scarani, Valerio

    2010-01-01

    We propose a method to generate analytical quantum Bell inequalities based on the principle of Macroscopic Locality. By imposing locality over binary processings of virtual macroscopic intensities, we establish a correspondence between Bell inequalities and quantum Bell inequalities in bipartite scenarios with dichotomic observables. We discuss how to improve the latter approximation and how to extend our ideas to scenarios with more than two outcomes per setting.

  17. Effect of Tempering Time on Microstructure, Tensile Properties, and Deformation Behavior of a Ferritic Light-Weight Steel

    Science.gov (United States)

    Han, Seung Youb; Shin, Sang Yong; Lee, Byeong-Joo; Lee, Sunghak; Kim, Nack J.; Kwak, Jai-Hyun

    2013-01-01

    In the present study, a ferritic light-weight steel was tempered at 973 K (700 °C) for various tempering times, and tensile properties and deformation mechanisms were investigated and correlated to microstructure. κ-carbides precipitated in the tempered band-shaped martensite and ferrite matrix, and the tempered martensite became more decomposed with increasing tempering time. Tempering times for 3 days or longer led to the formation of austenite as irregular thick-film shapes mostly along boundaries between the tempered martensite and the ferrite matrix. Tensile tests of the 1-day-tempered specimen showed that deformation bands were homogeneously spread throughout the specimen, and that the fine carbides were sufficiently deformed inside these deformation bands resulting in high strength and ductility. The 3-day-tempered specimen showed a small amount of boundary austenite, which readily developed voids or cracks and became sites for fracture. This cracking at boundary austenites became more prominent in the 7- and 15-day-tempered specimens, as the volume fraction of boundary austenites increased with increasing tempering time. These findings suggested that, when the steel was tempered at 973 K (700 °C) for an appropriate time, i.e., 1 day, to sufficiently precipitate κ-carbides and to prevent the formation of boundary austenites, that the deformation occurred homogeneously, leading to overall higher mechanical properties.

  18. Analysis of structure and deformation behavior of AISI 316L tensile specimens from the second operational target module at the Spallation Neutron Source

    Science.gov (United States)

    Gussev, M. N.; McClintock, D. A.; Garner, F. A.

    2016-01-01

    In an earlier publication, tensile testing was performed on specimens removed from the first two operational targets of the Spallation Neutron Source (SNS). There were several anomalous features in the results. First, some specimens had very large elongations (up to 57%) while others had significantly smaller values (10-30%). Second, there was a larger than the usual amount of data scatter in the elongation results. Third, the stress-strain diagrams of nominally similar specimens spanned a wide range of behavior ranging from expected irradiation-induced hardening to varying levels of force drop after yield point and indirect signs of "traveling deformation wave" behavior associated with strain-induced martensite formation. To investigate the cause(s) of such variable tensile behavior, several specimens from Target 2, spanning the range of observed tensile behavior, were chosen for detailed microstructural examination using electron backscatter diffraction (EBSD) analysis. It was shown that the steel employed in the construction of the target contained an unexpected bimodal grain size distribution, containing very large out-of-specification grains surrounded by "necklaces" of grains of within-specification sizes. The large grains were frequently comparable to the width of the gauge section of the tensile specimen. The propensity to form martensite during deformation was shown to be accelerated by radiation but also to be very sensitive to the relative orientation of the grains with respect to the tensile axis. Specimens having large grains in the gauge that were most favorably oriented for production of martensite strongly exhibited the traveling deformation wave phenomenon, while those specimens with less favorably oriented grains had lesser or no degree of the wave effect, thereby accounting for the observed data scatter.

  19. Investigation of Macroscopic Brittle Creep Failure Caused by Microcrack Growth Under Step Loading and Unloading in Rocks

    Science.gov (United States)

    Li, Xiaozhao; Shao, Zhushan

    2016-07-01

    The growth of subcritical cracks plays an important role in the creep of brittle rock. The stress path has a great influence on creep properties. A micromechanics-based model is presented to study the effect of the stress path on creep properties. The microcrack model of Ashby and Sammis, Charles' Law, and a new micro-macro relation are employed in our model. This new micro-macro relation is proposed by using the correlation between the micromechanical and macroscopic definition of damage. A stress path function is also introduced by the relationship between stress and time. Theoretical expressions of the stress-strain relationship and creep behavior are derived. The effects of confining pressure on the stress-strain relationship are studied. Crack initiation stress and peak stress are achieved under different confining pressures. The applied constant stress that could cause creep behavior is predicted. Creep properties are studied under the step loading of axial stress or the unloading of confining pressure. Rationality of the micromechanics-based model is verified by the experimental results of Jinping marble. Furthermore, the effects of model parameters and the unloading rate of confining pressure on creep behavior are analyzed. The coupling effect of step axial stress and confining pressure on creep failure is also discussed. The results provide implications on the deformation behavior and time-delayed rockburst mechanism caused by microcrack growth on surrounding rocks during deep underground excavations.

  20. Deformation behavior of carbon-fiber reinforced shape-memory-polymer composites used for deployable structures (Conference Presentation)

    Science.gov (United States)

    Lan, Xin; Liu, Liwu; Li, Fengfeng; Pan, Chengtong; Liu, Yanju; Leng, Jinsong

    2017-04-01

    Shape memory polymers (SMPs) are a new type of smart material, they perform large reversible deformation with a certain external stimulus (e.g., heat and electricity). The properties (e.g., stiffness, strength and other mechanically static or quasi-static load-bearing capacity) are primarily considered for conventional resin-based composite materials which are mainly used for structural materials. By contrast, the mechanical actuating performance with finite deformation is considered for the shape memory polymers and their composites which can be used for both structural materials and functional materials. For shape memory polymers and their composites, the performance of active deformation is expected to further promote the development in smart active deformation structures, such as deployable space structures and morphing wing aircraft. The shape memory polymer composites (SMPCs) are also one type of High Strain Composite (HSC). The space deployable structures based on carbon fiber reinforced shape memory polymer composites (SMPCs) show great prospects. Considering the problems that SMPCs are difficult to meet the practical applications in space deployable structures in the recent ten years, this paper aims to research the mechanics of deformation, actuation and failure of SMPCs. In the overall view of the shape memory polymer material's nonlinearity (nonlinearity and stress softening in the process of pre-deformation and recovery, relaxation in storage process, irreversible deformation), by the multiple verifications among theory, finite element and experiments, one obtains the deformation and actuation mechanism for the process of "pre-deformation, energy storage and actuation" and its non-fracture constraint domain. Then, the parameters of SMPCs will be optimized. Theoretical analysis is realized by the strain energy function, additionally considering the interaction strain energy between the fiber and the matrix. For the common resin-based or soft

  1. Comparative behavior of Sr, Nd and Hf isotopic systems during fluid-related deformation at middle crust levels

    Science.gov (United States)

    Luais, Béatrice; Le Carlier de Veslud, Christian; Géraud, Yves; Gauthier-Lafaye, François

    2009-05-01

    We have carried out a comparative Rb-Sr, Sm-Nd and Lu-Hf isotopic study of a progressively deformed hercynian leucogranite from the French Massif Central, belonging to the La Marche ductile shear zone, in order to investigate the respective perturbation of these geochronometers with fluid induced deformation. The one-meter wide outcrop presents a strongly deformed and mylonitized zone at the center, and an asymmetric deformation pattern with a higher deformation gradient on the northern side of the zone. Ten samples have been carefully collected every 10 cm North and South away from the strongest deformed mylonitic zone. They have been analyzed for a complete major, trace element data set, oxygen isotopes, Rb-Sr, Sm-Nd and Lu-Hf isotopic systematics. We show that most of major and trace elements except SiO 2, alkaline elements (K 2O, Rb), and some metal transition elements (Cu), are progressively depleted with increasing deformation. This depletion includes REE + Y, but also HFS elements (Ti, Hf, Zr, Nb) which are commonly considered as immobile elements during upper level processes. Variations in elemental ratios with deformation, e.g. decrease in LREE/MREE- HREE, Nd/Hf, Th/Sr, increase in Rb/Sr, U/Th and constant Sr/Nd, lead to propose the following order of element mobility: U ≫ Th > Sr = Nd ≫ Hf + HREE. We conclude in agreement with previous tectonic and metallogenic studies that trace element patterns across the shear zone result from circulation of oxidizing F-rich hydrothermal fluids associated with deformation. A temperature of the fluid of 470-480 °C can be deduced from the δ 18O equilibrium between quartz-muscovite pairs. Elemental fractionation induces perturbation of the Rb-Sr geochronometer. The well-defined 87Rb/ 86Sr- 87Sr/ 86Sr correlation gives an apparent age of 294 ± 19 Ma, slightly younger than the 323 ± 4 Ma age of leucogranites in this area. This apparent age is interpreted as dating event of intense deformation and fluid circulation

  2. FINITE ELEMENT ANALYSIS OF SUBSTRATE LOCAL PLASTIC DEFORMATION INDUCED BY CRACKED THIN HARD FILM

    Institute of Scientific and Technical Information of China (English)

    Zhu Youli; Ro(z)niatowski K; Kurzydlowski K; Huang Yuanlin; Xu Binshi

    2004-01-01

    It has been postulated that, with tensile loading conditions, micro-cracks on thin hard film act as stress concentrators enhancing plastic deformation of the substrate material in their vicinity. Under favorable conditions the localized plastic flow near the cracks may turn into macroscopic plastic strain thus affects the plasticity behaviors of the substrate. This phenomenon is analyzed quantitatively with finite element method with special attention focused on the analysis and discussion of the effects of plastic work hardening rate, film thickness and crack depth on maximum plastic strain, critical loading stress and the size of the local plastic deformation zone. Results show that micro-cracks on thin hard film have unnegligible effects on the plasticity behaviors of the substrate material under tensile loading.

  3. Effect of Strength Coefficient of Bainite on Micromechanical Deformation and Failure Behaviors of Hot-Rolled 590FB Steel during Uniaxial Tension

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-Young; Choi, Shi-Hoon [Sunchon National University, Suncheon (Korea, Republic of); Kim, Sung Il [POSCO Technical Research Laboratories, Gwangyang (Korea, Republic of)

    2016-11-15

    The effect of the strength coefficient (K{sub B}) of bainite on micromechanical deformation and failure behaviors of a hot-rolled 590MPa steel (590FB) during uniaxial tension was simulated using the elasto-plastic finite element method (FEM). The spatial distribution of the constituent phases was obtained using a phase identification technique based on optical microstructure. Empirical equations which depend on chemical composition were used to determine the stress-strain relationship of the constituent phases of the 590FB steel. The stress-strain partitioning and failure behavior were analyzed by increasing the K{sub B} of bainite. The elasto-plastic FEM results revealed that effective strain in the ferrite-bainite boundaries, and maximum principal stress in fibrous bainite, were enhanced as the K{sub B} increased. The elasto-plastic FEM results also demonstrated that the K{sub B} significantly affects the micromechanical deformation and failure behaviors of the hot-rolled 590FB steel during uniaxial tension.

  4. Mechanical Behaviour of Materials Volume 1 Micro- and Macroscopic Constitutive Behaviour

    CERN Document Server

    François, Dominique; Zaoui, André

    2012-01-01

    Advances in technology are demanding ever-increasing mastery over the materials being used: the challenge is to gain a better understanding of their behaviour, and more particularly of the relations between their microstructure and their macroscopic properties.   This work, of which this is the first volume, aims to provide the means by which this challenge may be met. Starting from the mechanics of deformation, it develops the laws governing macroscopic behaviour – expressed as the constitutive equations – always taking account of the physical phenomena which underlie rheological behaviour. The most recent developments are presented, in particular those concerning heterogeneous materials such as metallic alloys, polymers and composites. Each chapter is devoted to one of the major classes of material behaviour.   As the subtitles indicate, Volume 1 deals with micro- and macroscopic constitutive behaviour and Volume 2 with damage and fracture mechanics. A third volume will be devoted to exercises and the...

  5. Investigation of Mechanical Properties and Plastic Deformation Behavior of (Ti45Cu40Zr10Ni5100−xAlx Metallic Glasses by Nanoindentation

    Directory of Open Access Journals (Sweden)

    Lanping Huang

    2014-01-01

    Full Text Available The effect of Al addition on mechanical properties and plastic deformation behavior of (Ti45Cu40Zr10Ni5100−xAlx (x = 0, 2, 4, 6 and 8 amorphous alloy ribbons have been investigated by nanoindentation. The hardness and elastic modulus do not simply increase with the increase of Al content. The alloy with 8 at.% Al exhibits the highest hardness and elastic modulus. The serrations or pop-in events are strongly dependent on the loading rate and alloy composition.

  6. Effect of artificial aging on the deformation behavior of an Al-1.01Mg-0.68Si-1.78Cu alloy

    Institute of Scientific and Technical Information of China (English)

    HE Lizi; CHEN Yanbo; ZHANG Haitao; CUI Jianzhong

    2008-01-01

    The influences of artificial aging on the microstructures and mechanical properties of an AI-1.01Mg-0.68Si-1.78Cu alloy were investigated.The detailed fracture surfaces,precipitates,and dislocation structures were also examined through scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The results show that the tensile strengths exhibit two peak values and reach saturated values with increasing aging time,while the elongation decreases sharply to the minimum value and changes slightly later.The deformation and fracture behaviors arc also closely related to the aging conditions.

  7. Nanomechanical Properties and Deformation Behaviors of Multi-Component (AlCrTaTiZrNxSiy High-Entropy Coatings

    Directory of Open Access Journals (Sweden)

    Shao-Yi Lin

    2013-12-01

    Full Text Available In this study multi-component (AlCrTaTiZrNxSiy high-entropy coatings were developed by co-sputtering of AlCrTaTiZr alloy and Si in an Ar/N2 mixed atmosphere with the application of different substrate biases and Si-target powers. Their nanomechanical properties and deformation behaviors were characterized by nanoindentation tests. Because of the effect of high mixing entropies, all the deposited multi-component (AlCrTaTiZrNxSiy high-entropy coatings exhibited a simple face-centered cubic solid-solution structure. With an increased substrate bias and Si-target power, their microstructures changed from large columns with a [111] preferred orientation to a nanocomposite form with ultrafine grains. The hardness, H/E ratio and H3/E2 ratio of (AlCrTaTiZrN1.07Si0.15 coating reached 30.2 GPa, 0.12 and 0.41 GPa, respectively, suggesting markedly suppressed dislocation activities and a very high resistance to wear and plastic deformation, attributable to grain refinements and film densification by the application of substrate bias, a nanocomposite structure by the introduction of silicon nitrides, and a strengthening effect induced by severe lattice distortions. In the deformed regions under indents, stacking faults or partial dislocations were formed, while in the stress-released regions, near-perfect lattices recovered.

  8. Insights into the deformation behavior of the CrMnFeCoNi high-entropy alloy revealed by elevated temperature nanoindentation

    Energy Technology Data Exchange (ETDEWEB)

    Maier-Kiener, Verena [Montanuniversitat Leoben, Leoben (Austria); Schuh, Benjamin [Austrian Academy of Sciences, Leoben (Austria); George, Easo P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Clemens, Helmut [Montanuniversitat Leoben, Leoben (Austria); Hohenwarter, Anton [Austrian Academy of Sciences, Leoben (Austria)

    2017-07-27

    A CrMnFeCoNi high-entropy alloy was investigated by nanoindentation from room temperature to 400 °C in the nanocrystalline state and cast plus homogenized coarse-grained state. In the latter case a < 100 >-orientated grain was selected by electron back scatter diffraction for nanoindentation. It was found that hardness decreases more strongly with increasing temperature than Young’s modulus, especially for the coarse-grained state. The modulus of the nanocrystalline state was slightly higher than that of the coarse-grained one. For the coarse-grained sample a strong thermally activated deformation behavior was found up to 100–150 °C, followed by a diminishing thermally activated contribution at higher testing temperatures. For the nanocrystalline state, different temperature dependent deformation mechanisms are proposed. At low temperatures, the governing processes appear to be similar to those in the coarse-grained sample, but with increasing temperature, dislocation-grain boundary interactions likely become more dominant. Finally, at 400 °C, decomposition of the nanocrystalline alloy causes a further reduction in thermal activation. Furthermore, this is rationalized by a reduction of the deformation controlling internal length scale by precipitate formation in conjunction with a diffusional contribution.

  9. Deformation Behavior and Microstructure Evolution of As-Cast 42CrMo Alloy in Isothermal and Non-isothermal Compression

    Science.gov (United States)

    Qin, Fangcheng; Li, Yongtang; Qi, Huiping; Lv, Zhenhua

    2016-11-01

    The isothermal and non-isothermal multi-pass compression tests of centrifugal casting 42CrMo steel were conducted on a Gleeble-3500 thermal simulation machine. The effects of compression passes and finishing temperatures on deformation behavior and microstructure evolution were investigated. It is found that the microstructure is homogeneous with equiaxed grains, and the flow stress does not show significant change with the increase in passes, while the peak softening coefficient increases first and then decreases during inter-pass. Moreover, the dominant mechanisms of controlled temperature and accumulated static recrystallization for grain refinement and its homogeneous distribution are found after 5 passes deformation. As the finishing temperature increases, the flow stress decreases gradually, but the dynamic recrystallization accelerates and softening effect increases, resulting in the larger grain size and homogeneous microstructure. The microhardness decreases sharply because the sufficient softening occurs in microstructure. When the finishing temperature is 890 °C, the carbide particles are precipitated in the vicinity of the grain boundaries, thus inhibiting the dislocation motion. Thus, the higher finishing temperature (≥970 °C) for centrifugal casting 42CrMo alloy should be avoided in non-isothermal multi-pass deformation, which is beneficial to grain refinement and properties improvement.

  10. Analytical modeling of the thermomechanical behavior of ASTM F-1586 high nitrogen austenitic stainless steel used as a biomaterial under multipass deformation.

    Science.gov (United States)

    Bernardes, Fabiano R; Rodrigues, Samuel F; Silva, Eden S; Reis, Gedeon S; Silva, Mariana B R; Junior, Alberto M J; Balancin, Oscar

    2015-06-01

    Precipitation-recrystallization interactions in ASTM F-1586 austenitic stainless steel were studied by means of hot torsion tests with multipass deformation under continuous cooling, simulating an industrial laminating process. Samples were deformed at 0.2 and 0.3 at a strain rate of 1.0s(-1), in a temperature range of 900 to 1200°C and interpass times varying from 5 to 80s. The tests indicate that the stress level depends on deformation temperature and the slope of the equivalent mean stress (EMS) vs. 1/T presents two distinct behaviors, with a transition at around 1100°C, the non-recrystallization temperature (Tnr). Below the Tnr, strain-induced precipitation of Z-phase (NbCrN) occurs in short interpass times (tpass<30s), inhibiting recrystallization and promoting stepwise stress build-up with strong recovery, which is responsible for increasing the Tnr. At interpass times longer than 30s, the coalescence and dissolution of precipitates promote a decrease in the Tnr and favor the formation of recrystallized grains. Based on this evidence, the physical simulation of controlled processing allows for a domain refined grain with better mechanical properties.

  11. Chaotic advection at the pore scale: Mechanisms, upscaling and implications for macroscopic transport

    Science.gov (United States)

    Lester, D. R.; Trefry, M. G.; Metcalfe, G.

    2016-11-01

    The macroscopic spreading and mixing of solute plumes in saturated porous media is ultimately controlled by processes operating at the pore scale. Whilst the conventional picture of pore-scale mechanical dispersion and molecular diffusion leading to persistent hydrodynamic dispersion is well accepted, this paradigm is inherently two-dimensional (2D) in nature and neglects important three-dimensional (3D) phenomena. We discuss how the kinematics of steady 3D flow at the pore scale generate chaotic advection-involving exponential stretching and folding of fluid elements-the mechanisms by which it arises and implications of microscopic chaos for macroscopic dispersion and mixing. Prohibited in steady 2D flow due to topological constraints, these phenomena are ubiquitous due to the topological complexity inherent to all 3D porous media. Consequently 3D porous media flows generate profoundly different fluid deformation and mixing processes to those of 2D flow. The interplay of chaotic advection and broad transit time distributions can be incorporated into a continuous-time random walk (CTRW) framework to predict macroscopic solute mixing and spreading. We show how these results may be generalised to real porous architectures via a CTRW model of fluid deformation, leading to stochastic models of macroscopic dispersion and mixing which both honour the pore-scale kinematics and are directly conditioned on the pore-scale architecture.

  12. Macroscopic optical response and photonic bands

    CERN Document Server

    Perez-Huerta, J S; Mendoza, Bernardo S; Mochan, W Luis

    2012-01-01

    We develop a formalism for the calculation of the macroscopic dielectric response of composite systems made of particles of one material embedded periodically within a matrix of another material, each of which is characterized by a well defined dielectric function. The nature of these dielectric functions is arbitrary, and could correspond to dielectric or conducting, transparent or opaque, absorptive and dispersive materials. The geometry of the particles and the Bravais lattice of the composite are also arbitrary. Our formalism goes beyond the longwavelenght approximation as it fully incorporates retardation effects. We test our formalism through the study the propagation of electromagnetic waves in 2D photonic crystals made of periodic arrays of cylindrical holes in a dispersionless dielectric host. Our macroscopic theory yields a spatially dispersive macroscopic response which allows the calculation of the full photonic band structure of the system, as well as the characterization of its normal modes, upo...

  13. A macroscopic challenge for quantum spacetime

    CERN Document Server

    Amelino-Camelia, Giovanni

    2013-01-01

    Over the last decade a growing number of quantum-gravity researchers has been looking for opportunities for the first ever experimental evidence of a Planck-length quantum property of spacetime. These studies are usually based on the analysis of some candidate indirect implications of spacetime quantization, such as a possible curvature of momentum space. Some recent proposals have raised hope that we might also gain direct experimental access to quantum properties of spacetime, by finding evidence of limitations to the measurability of the center-of-mass coordinates of some macroscopic bodies. However I here observe that the arguments that originally lead to speculating about spacetime quantization do not apply to the localization of the center of mass of a macroscopic body. And I also analyze some popular formalizations of the notion of quantum spacetime, finding that when the quantization of spacetime is Planckian for the constituent particles then for the composite macroscopic body the quantization of spa...

  14. On Macroscopic Complexity and Perceptual Coding

    CERN Document Server

    Scoville, John

    2010-01-01

    While Shannon information establishes limits to the universal data compression of binary data, no existing theory provides an equivalent characterization of the lossy data compression algorithms prevalent in audiovisual media. The current paper proposes a mathematical framework for perceptual coding and inference which quantifies the complexity of objects indistinguishable to a particular observer. A definition of the complexity is presented and related to a generalization of Boltzmann entropy for these equivalence classes. When the classes are partitions of phase space, corresponding to classical observations, this is the proper Boltzmann entropy and the macroscopic complexity agrees with the Algorithmic Entropy. For general classes, the macroscopic complexity measure determines the optimal lossy compression of the data. Conversely, perceptual coding algorithms may be used to construct upper bounds on certain macroscopic complexities. Knowledge of these complexities, in turn, allows perceptual inference whic...

  15. Nanoplasmon-enabled macroscopic thermal management

    CERN Document Server

    Jonsson, Gustav Edman; Dmitriev, Alexandre

    2013-01-01

    In numerous applications of energy harvesting via transformation of light into heat the focus recently shifted towards highly absorptive materials featuring nanoplasmons. It is currently established that noble metals-based absorptive plasmonic platforms deliver significant light-capturing capability and can be viewed as super-absorbers of optical radiation. However, direct experimental evidence of plasmon-enabled macroscopic temperature increase that would result from these efficient absorptive properties is scarce. Here we derive a general quantitative method of characterizing light-capturing properties of a given heat-generating absorptive layer by macroscopic thermal imaging. We further monitor macroscopic areas that are homogeneously heated by several degrees with plasmon nanostructures that occupy a mere 8% of the surface, leaving it essentially transparent and evidencing significant heat generation capability of nanoplasmon-enabled light capture. This has a direct bearing to thermophotovoltaics and othe...

  16. Macroscopic modeling for traffic flow on three-lane highways

    Science.gov (United States)

    Chen, Jianzhong; Fang, Yuan

    2015-04-01

    In this paper, a macroscopic traffic flow model for three-lane highways is proposed. The model is an extension of the speed gradient model by taking into account the lane changing. The new source and sink terms of lane change rate are added into the continuity equations and the speed dynamic equations to describe the lane-changing behavior. The result of the steady state analysis shows that our model can describe the lane usage inversion phenomenon. The numerical results demonstrate that the present model effectively reproduces several traffic phenomena observed in real traffic such as shock and rarefaction waves, stop-and-go waves and local clusters.

  17. Effect of Vanadium on the Hot Deformation Behavior of Vanadium-Microalloyed Steel for Thin Slab Direct Rolling

    Science.gov (United States)

    Lee, Chang Wook; Seong, Hwan Goo; De Cooman, Bruno C.

    2016-07-01

    The effects of V on hot deformation properties of low-carbon steel were investigated in the temperature range of 1173 K to 1473 K (900 °C to 1200 °C) and for strain rates from 0.1 to 5 s-1 for compositions with a V content in the range of 0 to 0.125 wt pct. The critical stress and strain for dynamic recrystallization (DRX) initiation were obtained from the stress dependence of the strain hardening rate. The hot deformation properties of V-alloyed steel were studied in function of the temperature-corrected strain rate. The experimental results were used to construct a kinetic model of DRX. V was found to have no influence on the hot deformation properties for V contents less than 0.125 pct, indicating the absence of both solute drag and precipitation effects at low V content. When the V content reached 0.125 wt pct, the activation energy for DRX increased and DRX was suppressed in high strain rate condition.

  18. Microstructure and annealing behavior of a modified 9Cr-1Mo steel after dynamic plastic deformation to different strains

    Science.gov (United States)

    Zhang, Z. B.; Mishin, O. V.; Tao, N. R.; Pantleon, W.

    2015-03-01

    The microstructure, hardness and tensile properties of a modified 9Cr-1Mo steel processed by dynamic plastic deformation (DPD) to different strains (0.5 and 2.3) have been investigated in the as-deformed and annealed conditions. It is found that significant structural refinement and a high level of strength can be achieved by DPD to a strain of 2.3, and that the microstructure at this strain contains a large fraction of high angle boundaries. The ductility of the DPD processed steel is however low. Considerable structural coarsening of the deformed microstructure without pronounced recrystallization takes place during annealing of the low-strain and high-strain samples for 1 h at 650 °C and 600 °C, respectively. Both coarsening and partial recrystallization occur in the high-strain sample during annealing at 650 °C for 1 h. For this sample, it is found that whereas coarsening alone results in a loss of strength with only a small gain in ductility, coarsening combined with pronounced partial recrystallization enables a combination of appreciably increased ductility and comparatively high strength.

  19. Microstructure and annealing behavior of a modified 9Cr−1Mo steel after dynamic plastic deformation to different strains

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.B.; Mishin, O.V. [Danish-Chinese Center for Nanometals, Section for Materials Science and Advanced Characterization, Department of Wind Energy, Technical University of Denmark, Risø Campus, 4000 Roskilde (Denmark); Sino-Danish Center for Education and Research (China); Sino-Danish Center for Education and Research (Denmark); Tao, N.R. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Science, Shenyang 110016 (China); Sino-Danish Center for Education and Research (China); Sino-Danish Center for Education and Research (Denmark); Pantleon, W., E-mail: pawo@dtu.dk [Section for Materials and Surface Engineering, Department of Mechanical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark); Sino-Danish Center for Education and Research (China); Sino-Danish Center for Education and Research (Denmark)

    2015-03-15

    The microstructure, hardness and tensile properties of a modified 9Cr−1Mo steel processed by dynamic plastic deformation (DPD) to different strains (0.5 and 2.3) have been investigated in the as-deformed and annealed conditions. It is found that significant structural refinement and a high level of strength can be achieved by DPD to a strain of 2.3, and that the microstructure at this strain contains a large fraction of high angle boundaries. The ductility of the DPD processed steel is however low. Considerable structural coarsening of the deformed microstructure without pronounced recrystallization takes place during annealing of the low-strain and high-strain samples for 1 h at 650 °C and 600 °C, respectively. Both coarsening and partial recrystallization occur in the high-strain sample during annealing at 650 °C for 1 h. For this sample, it is found that whereas coarsening alone results in a loss of strength with only a small gain in ductility, coarsening combined with pronounced partial recrystallization enables a combination of appreciably increased ductility and comparatively high strength.

  20. Hot deformation behavior and dynamic recrystallization kinetics of AZ61 and AZ61 + Sr magnesium alloys

    Directory of Open Access Journals (Sweden)

    S. Aliakbari Sani

    2016-06-01

    Full Text Available In this study, the effect of strontium addition on hot deformation of AZ61 alloy was investigated by hot compression tests. A reference alloy (AZ61 and an Sr-containing alloy (AZ61 + Sr was cast while their average initial grain size were supposed to be about 140 and 40 µm, respectively. In AZ61 + Sr alloy, the Sr-containing precipitations were stable at homogenization temperature. Analysing the hot compression curves, it was revealed that dynamic recrystallization phenomenon had occurred and controlled the thermomechanical behaviour of the alloys. The derived constitutive equations showed that the hot deformation parameters (n and Q in AZ61 + Sr alloy is smaller than those of AZ61 alloy; this can be related to the small initial grain size and the lower amounts of solute aluminium atoms. The analysis of DRX kinetics along with the micrographs of the deformed microstructures showed that at the same condition the development of DRXed microstructure in AZ61 + Sr alloy was faster than AZ61 alloy. The increased recrystallized microstructure was interpretated to be attributed to (1 the more grain boundaries present and (2 the existance of the Al-Mg-Sr precipitations assisted the PSN mechanism. Also, the attenuated intensity of the basal texture of AZ61 + Sr was related to the DRX fraction of microstructure.

  1. Measurement of large deformation of nylon cord-rubber composite and effects of perpendicular loads on its stress-strain behaviors

    Institute of Scientific and Technical Information of China (English)

    张丰发; 杜星文; 于增信

    2003-01-01

    Effects of transverse loads on longitudinal stress-strain behaviors and longitudinal constant tensile loads on transverse stress-strain behaviors of single ply of nylon cord-rubber composite are studied respectively under biaxial tensile condition with cruciform specimen. Effects of transverse constant tensile load on longitudinal tensile mechanical properties are indistinctive compared with corresponding uniaxial longitudinal tensile mechanical properties. It can be relative to larger difference between longitudinal and transverse mechanical properties. Its dominating failure mode is typical fiber-dominated mode; However, Experiment results indicate that transverse mechanical properties of nylon cord-rubber composite with longitudinal constant tensile loads are distinct from its uniaxial transverse tensile mechanical properties. It can be attribute to action of longitudinal tension that makes material rigidify in the direction perpendicular to fiber, Mode of failure is representative of matrix-dominated failure. For the measurement of large deformation up to 50 percent, a special CCD imaging method is employed in the experimental investigation that makes measurement of large deformations more precise.

  2. New insight into deformation-dependent hydraulic permeability of gels and cartilage, and dynamic behavior of agarose gels in confined compression.

    Science.gov (United States)

    Gu, W Y; Yao, H; Huang, C Y; Cheung, H S

    2003-04-01

    Equilibrium, creep, and dynamic behaviors of agarose gels (2.0-14.8%) in confined compression were investigated in this study. The hydraulic permeabilities of gels were determined by curve-fitting creep data to the biphasic model (J. Biomech. Eng. 102 (1980) 73) and found to be similar in value to those published in the literature (AIChE J. 42 (1996) 1220). A new relationship between intrinsic permeability and volume fraction of water was found for agarose gel, capable of predicting deformation-dependent permeabilities of bovine articular cartilage and 2% agarose gel published in literature. This relationship is accurate for gels and cartilage over a wide range of permeabilities (four orders of magnitude variation). The dynamic stiffness of the gels increases with gel concentration and loading frequency (0.01-1.0Hz). The increase in dynamic stiffness with loading frequency is less pronounced for gels with higher concentrations. The results of this study provide a new insight into deformation-dependent permeability behavior of agarose gel and cartilage, and are important for understanding biological responses of cells to interstitial fluid flow in gel or in cartilage under dynamic mechanical loading.

  3. On the geometric relationship between deformation microstructures in zircon and the kinematic framework of the shear zone

    Science.gov (United States)

    Kovaleva, Elizaveta; Klötzli, Urs; Habler, Gerlinde

    2016-10-01

    independent of zircon's grain size and shape, and reflect the strong geometric control of the macroscopic kinematic rotation axis on the crystal-plastic deformation behavior of zircon and on the geometry of its slip systems. We describe previously unknown rheological and crystallographic properties of zircon, which suggest a tool for deriving an orientation of the plastically deformed zircon crystals with respect to the associated foliation and stretching lineation. Additionally, relationships between zircon deformation microstructures and the macroscopic kinematic framework have implications for zircon geochronology. If deformation events result in zircon distortion and, as a consequence, partial or complete resetting of the zircon isotopic system, the age of deformation can be accurately dated.

  4. Macroscopic Dynamical Description of Rotating au + au System

    Science.gov (United States)

    Cârjan, N.; Siwek-Wilczyńska, K.; Skwira-Chalot, I.; Wilczyński, J.

    Events with more than two heavy fragments have been abundantly observed in heavy-ion semi-peripheral (fission-like) reaction 197Au+197Au at 15 MeV/nucleon. This raised interesting questions about their origin and about the time-scale at which they occur. As a possible explanation of this process, the surface instability of the cylindrical neck that is formed along the path from contact to reseparation of the rotating Au+Au system is investigated in the present paper. For this purpose the Los Alamos finite-range macroscopic dynamical model was used. The calculations were performed at relatively high angular momenta, L = 100 to 300 ħ, for two types of dissipation mechanisms: two-body viscosity and one-body dissipation. Various initial nuclear deformations and initial kinetic energies in the fission direction were considered. The resulting dynamical evolution in the multidimensional deformation space always led to multifragment scission configurations suggesting that ternary and quaternary break-up can occur during the heavy-ion reaction studied.

  5. Separation of the Microscopic and Macroscopic Domains

    Science.gov (United States)

    Van Zandt, L. L.

    1977-01-01

    Examines the possibility of observing interference in quantum magnification experiments such as the celebrated "Schroedinger cat". Uses the possibility of observing interference for separating the realm of microscopic from macroscopic dynamics; estimates the dividing line to fall at system sizes of about 100 Daltons. (MLH)

  6. Entropy, Macroscopic Information, and Phase Transitions

    OpenAIRE

    Parrondo, Juan M. R.

    1999-01-01

    The relationship between entropy and information is reviewed, taking into account that information is stored in macroscopic degrees of freedom, such as the order parameter in a system exhibiting spontaneous symmetry breaking. It is shown that most problems of the relationship between entropy and information, embodied in a variety of Maxwell demons, are also present in any symmetry breaking transition.

  7. Macroscopic Modeling of Polymer-Electrolyte Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Weber, A.Z.; Newman, J.

    2007-04-01

    In this chapter, the various approaches for the macroscopic modeling of transport phenomena in polymer-electrolyte membranes are discussed. This includes general background and modeling methodologies, as well as exploration of the governing equations and some membrane-related topic of interest.

  8. Lozenge Tilings, Glauber Dynamics and Macroscopic Shape

    Science.gov (United States)

    Laslier, Benoît; Toninelli, Fabio Lucio

    2015-09-01

    We study the Glauber dynamics on the set of tilings of a finite domain of the plane with lozenges of side 1/ L. Under the invariant measure of the process (the uniform measure over all tilings), it is well known (Cohn et al. J Am Math Soc 14:297-346, 2001) that the random height function associated to the tiling converges in probability, in the scaling limit , to a non-trivial macroscopic shape minimizing a certain surface tension functional. According to the boundary conditions, the macroscopic shape can be either analytic or contain "frozen regions" (Arctic Circle phenomenon Cohn et al. N Y J Math 4:137-165, 1998; Jockusch et al. Random domino tilings and the arctic circle theorem, arXiv:math/9801068, 1998). It is widely conjectured, on the basis of theoretical considerations (Henley J Statist Phys 89:483-507, 1997; Spohn J Stat Phys 71:1081-1132, 1993), partial mathematical results (Caputo et al. Commun Math Phys 311:157-189, 2012; Wilson Ann Appl Probab 14:274-325, 2004) and numerical simulations for similar models (Destainville Phys Rev Lett 88:030601, 2002; cf. also the bibliography in Henley (J Statist Phys 89:483-507, 1997) and Wilson (Ann Appl Probab 14:274-325, 2004), that the Glauber dynamics approaches the equilibrium macroscopic shape in a time of order L 2+ o(1). In this work we prove this conjecture, under the assumption that the macroscopic equilibrium shape contains no "frozen region".

  9. Macroscopic invisibility cloaking of visible light

    DEFF Research Database (Denmark)

    Chen, Xianzhong; Luo, Y.; Zhang, Jingjing

    2011-01-01

    to a few wavelengths. Here, we report the first realization of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding, for a specific light polarization, three-dimensional objects of the scale...

  10. Synergistic effect of austenitizing temperature and hot plastic deformation strain on the precipitation behavior in novel HSLA steel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chih-Yuan, E-mail: chen6563@gmail.com [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chen, Chien-Chon [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Yang, Jer-Ren, E-mail: jryang@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2015-07-15

    Examination of thin foils of specimens with various austenitizing conditions by transmission electron microscopy revealed randomly homogeneous precipitation in the ferrite for each experimental condition. Though no interphase precipitation was found in the present study, two types of random precipitation morphologies were identified in the ferrite matrix. One was randomly and homogeneously precipitated carbides of smaller size (<10 nm), and the other was randomly precipitated carbides of larger size (10–30 nm). Transmission electron microscopy results provided evidence that both types of precipitation carbides could be associated with the supersaturation of microalloying elements in the ferrite and austenite, respectively. A higher austenitizing temperature treatment can lead to more microalloying elements dissolving in the austenite such that many tiny carbides precipitation at the low isothermal holding temperature, which is believed to effectively strengthen the ferrite. Vickers hardness data revealed that, in specimens austenitized at 1200 °C and deformed at 900 °C with strains of 10% and 30%, the ranges of hardness distribution were 250–360 HV 0.1 and 310–400 HV 0.1, respectively. For specimens austenitized at 1000 °C and deformed at 900 °C with strains of 10% and 30%, the ranges of hardness distribution were 220–250 HV 0.1 and 220–260 HV 0.1, respectively. Therefore, the average Vickers hardness increased with the austenitizing temperature and deformation strain. However, a wider range of hardness distribution occurred in specimens that underwent treatment at higher austenitizing temperatures. The wider Vickers hardness distribution reflects non-uniform precipitation in each ferrite grain.

  11. Research on Hot Deformation Behavior of Hastelloy G-3 Alloy%Hastelloy G-3合金热变形特性研究

    Institute of Scientific and Technical Information of China (English)

    罗坤杰; 张麦仓; 王宝顺; 董建新

    2011-01-01

    利用变形温度为1050~1200℃、应变速率为0.1~10 s-1的恒温热压缩试验系统分析了Hastelloy G-3合金的高温变形特性及变形后的组织特征.对高应变速率下的流动应力进行变形热效应修正,建立了G-3合金热变形过程中峰值应力与变形温度、应变速率关系的本构模型.结果表明:所建立的本构模型在预测G-3合金热变形峰值应力时具有良好的精确度,能够满足工程应用的要求.G-3合金热加工过程的软化机制为动态再结晶,根据热变形后的组织特征确定G-3合金合理的热变形温度为1180~1200℃,应变速率为5~10 s-1.%The hot deformation behavior and the subsequent microstructure characteristics of Hastelloy G-3 alloy were studied by isothermal compression tests at the strain rates of 0.1-10 s-1 and the temperatures of 1050-1200 ℃. The flow-stress at high strain rates were corrected considering the effect of deformation heating, and a new constitutive relationship between peak stress and deformation temperature as well as strain rate for G-3 alloy at high temperature was established. The results show that the built material model has good fitting accuracy to satisfy the engineering need. The softening mechanism of G-3 alloy is dynamic recrystalization during hot working process. According to the microstructures after deformation, for G-3 alloy the proper deformation temperature is 1180-1200 ℃ and the proper strain rate is 5-10 s-1.

  12. Research on hot deformation behavior of 3003 Al alloy%3003铝合金热变形行为

    Institute of Scientific and Technical Information of China (English)

    陈贵清; 傅高升; 颜文煅; 陈鸿玲; 程超增; 邹泽昌

    2011-01-01

    3003 Al alloys with different metallurgical quality were obtained by different melt-treatment methods, which were deformed by isothermal compression in the range of deformation temperature 300℃~500℃ at strain rate 0. 01s-1 ~ 10. 0s-1 with Gleeble-1500 thermal simulator. The results show that the material is sensitive to positive strain rate, the linear relationship between the hot deformation activation energy Q and inclusion content H is Q=35. 62H+171. 58, and the activation energy of 3003 Al alloy prepared by high melt-treatment is the lowest 174. 62kJ · mol-1 which is beneficial to the hot plastic deformation of material. The critical strain of 3003 Al alloy prepared by different melt-treatment methods were calculated with work hardening rate, and the critical conditions to predict the dynamic recrystallization occurrence for the 3003 Al alloys prepared by different melt-treatment methods were obtained.%采用不同熔体处理工艺获得3种不同冶金质量的3003铝合金,通过Gleeble-1500热模拟试验机对3003铝合金进行变形温度为300℃~500℃,应变速率为0.01s-1~10s-1高温等温压缩实验.结果表明,3003铝合金具有正的应变速率敏感性,热变形激活能Q与含杂量H呈线性关系,经高效综合处理的3003铝合金热变形激活能最低为174.62kJ·mol-1,有利于材料热塑性变形.采用加工硬化率计算不同熔体处理的3003铝合金的临界应变值,获得了经不同熔体处理的3003铝合金发生动态再结晶的临界条件.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Macroscopic Quantum Phenomena from the Correlation, Coupling and Criticality Perspectives

    CERN Document Server

    Chou, C H; Subasi, Y

    2011-01-01

    In this sequel paper we explore how macroscopic quantum phenomena can be measured or understood from the behavior of quantum correlations which exist in a quantum system of many particles or components and how the interaction strengths change with energy or scale, under ordinary situations and when the system is near its critical point. We use the nPI (master) effective action related to the Boltzmann-BBGKY / Schwinger-Dyson hierarchy of equations as a tool for systemizing the contributions of higher order correlation functions to the dynamics of lower order correlation functions. Together with the large N expansion discussed in our first paper(MQP1) we explore 1) the conditions whereby an H-theorem is obtained, which can be viewed as a signifier of the emergence of macroscopic behavior in the system. We give two more examples from past work: 2) the nonequilibrium dynamics of N atoms in an optical lattice under the large $\\cal N$ (field components), 2PI and second order perturbative expansions, illustrating h...

  15. Dynamic tensile deformation behavior of Zr-based amorphous alloy matrix composites reinforced with tungsten or tantalum fibers

    Science.gov (United States)

    Lee, Hyungsoo; Kim, Gyeong Su; Jeon, Changwoo; Sohn, Seok Su; Lee, Sang-Bok; Lee, Sang-Kwan; Kim, Hyoung Seop; Lee, Sunghak

    2016-07-01

    Zr-based amorphous alloy matrix composites reinforced with tungsten (W) or tantalum (Ta) continuous fibers were fabricated by liquid pressing process. Their dynamic tensile properties were investigated in relation with microstructures and deformation mechanisms by using a split Hopkinson tension bar. The dynamic tensile test results indicated that the maximum strength of the W-fiber-reinforced composite (757 MPa) was much lower than the quasi-statically measured strength, whereas the Ta-fiber-reinforced composite showed very high maximum strength (2129 MPa). In the W-fiber-reinforced composite, the fracture abruptly occurred in perpendicular to the tensile direction because W fibers did not play a role in blocking cracks propagated from the amorphous matrix, thereby resulting in abrupt fracture within elastic range and consequent low tensile strength. The very high dynamic tensile strength of the Ta-fiber-reinforced composite could be explained by the presence of ductile Ta fibers in terms of mechanisms such as (1) interrupted propagation of cracks initiated in the amorphous matrix, (2) formation of lots of cracks in the amorphous matrix, and (3) sharing of loads and severe deformation (necking) of Ta fibers in cracked regions.

  16. Vortex core deformation and stepper-motor ratchet behavior in a superconducting aluminum film containing an array of holes.

    Science.gov (United States)

    Van de Vondel, J; Gladilin, V N; Silhanek, A V; Gillijns, W; Tempere, J; Devreese, J T; Moshchalkov, V V

    2011-04-01

    We investigated experimentally the frequency dependence of a superconducting vortex ratchet effect by means of electrical transport measurements and modeled it theoretically using the time-dependent Ginzburg-Landau formalism. We demonstrate that the high frequency vortex behavior can be described as a discrete motion of a particle in a periodic potential, i.e., the so-called stepper-motor behavior. Strikingly, in the more conventional low frequency response a transition takes place from an Abrikosov vortex rectifier to a phase slip line rectifier. This transition is characterized by a strong increase in the rectified voltage and the appearance of a pronounced hysteretic behavior.

  17. Apparatus for measuring the finite load-deformation behavior of a sheet of epithelial cells cultured on a mesoscopic freestanding elastomer membrane

    Science.gov (United States)

    Selby, John C.; Shannon, Mark A.

    2007-09-01

    Details are given for the design, calibration, and operation of an apparatus for measuring the finite load-deformation behavior of a sheet of living epithelial cells cultured on a mesoscopic freestanding elastomer membrane, 10μm thick and 5mm in diameter. Although similar in concept to bulge tests used to investigate the mechanical properties of micromachined thin films, cell-elastomer composite diaphragm inflation tests pose a unique set of experimental challenges. Composite diaphragm (CD) specimens are extremely compliant (Eexperience large displacements when subject to small inflation pressures (˜100Pa), and must be continuously immersed in a bath of liquid culture medium during the acquisition of load-deformation measurements. Given these considerations, we have constructed an inflation apparatus consisting of an air-piston-cylinder pump integrated with a modular specimen mounting fixture that constitutes a horizontally semi-infinite reservoir of liquid culture medium. In a deformation-controlled inflation test, pressurized air is used to inflate a CD specimen into the liquid reservoir with minimum disturbance of the liquid-air interface. Piston displacements and absolute pump chamber air pressures are utilized as feedback to cycle the displaced (or inflated) CD volume V in a 0.05Hz triangular or sinusoidal wave form (VMIN=0μl, VMAX⩽40μl) while simultaneously recording the inflation pressure acting at the fixed boundary of the specimen, p(r =a). Using a carefully prescribed six-cycle inflation test protocol, the apparatus is shown to be capable of measuring the [V,p(r=a)] inflation response of a cell-elastomer CD with random uncertainties estimated at ±0.45μl and ±2.5Pa, respectively.

  18. Deformation behavior and load limits of asphaltic concrete under the conditions of cores in embankment dams; Deformationsverhalten und Belastungsgrenzen des Asphaltbetons unter den Bedingungen von Staudammkerndichtungen

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, U.

    1998-12-31

    Based on the analysis of existing dams with asphaltic diaphragm and investigations in the three-phase-system of asphaltic concrete a recipe for the composition of asphaltic cores is recommended. For the construction, rest and operating period of an embankment dam the load and the reaction of the asphaltic concrete cores as well as the appearing stress and deformations are described. Extensive material testings have been performed and at 41 asphaltic concrete specimens triaxial stress controlled pressure and creeping tests have been carried out. The evaluation of the triaxial tests led to proportions of the main stress and deformation limits as criteria of breaking. Under application of the standard equation for nonlinear viscoelastic element-laws a rheonom element formulation was developed from the experiment data and transformed into its differential form. With this approach the stress and deformation behavior of watertight asphaltic diaphragm can be precalculated for a period up to 10 years. The applicability of this approach, which can be also used within FE-calculations as well, is illustrated in four examples. (orig.) [Deutsch] Nach der Analyse bestehender Staudaemme mit Asphaltbetonkerndichtung und Untersuchungen zum Dreiphasensystem Asphaltbeton wird eine Rezepturempfehlung fuer den Asphaltkerndichtungsbau aufgestellt. Fuer die Bau-, Ruhe- und Betriebsphase eines Staudammes werden die Beanspruchungen und Reaktionen der Asphaltbetonkerndichtung sowie die auftretenden Spannungen und Verformungen beschrieben. Nach umfangreichen Materialpruefungen sind an 41 Asphaltbetonpruefkoerpern triaxiale spannungsgesteuerte Druck-Kriechversuche durchgefuehrt worden. Die Auswertung der Triaxialversuche ergab ein Grenzhauptspannungsverhaeltnis und Deformationsgrenzen als Bruchkriterien. Unter Verwendung der Standarformulierung fuer nichtlineare viskoelastische Stoffgesetze wurde aus den Versuchsdaten ein rheonomer Stoffansatz entwickelt und in seine differentielle Form

  19. Macroscopic acousto-mechanical analogy of a microbubble

    CERN Document Server

    Chaline, Jennifer; Mehrem, Ahmed; Bouakaz, Ayache; Santos, Serge Dos; Sánchez-Morcillo, Víctor J

    2015-01-01

    Microbubbles, either in the form of free gas bubbles surrounded by a fluid or encapsulated bubbles used currently as contrast agents for medical echography, exhibit complex dynamics under specific acoustic excitations. Nonetheless, considering their micron size and the complexity of their interaction phenomenon with ultrasound waves, expensive and complex experiments and/or simulations are required for their analysis. The behavior of a microbubble along its equator can be linked to a system of coupled oscillators. In this study, the oscillatory behavior of a microbubble has been investigated through an acousto-mechanical analogy based on a ring-shaped chain of coupled pendula. Observation of parametric vibration modes of the pendula ring excited at frequencies between $1$ and $5$ Hz is presented. Simulations have been carried out and show mode mixing phenomena. The relevance of the analogy between a microbubble and the macroscopic acousto-mechanical setup is discussed and suggested as an alternative way to in...

  20. Experimental and Numerical Research on Deformation Behavior of Thin-Walled and Large Expansion Ratio Guide Vane Liner in Hydroforming Process

    Institute of Scientific and Technical Information of China (English)

    Pengzhi Cheng; Lihui Lang; Yulong Ge; Shangwen Ruan; Xinmin Duan; Tianwei Shao

    2015-01-01

    Some tube hydroforming process tests and further research work were conducted to manufacture hollow guide vane liners (made of super alloy GH3030).The relative thickness (t0/OD) of the tubular blank is approximately 0�01,and the maximum expansion ratio ( Dmax/OD) of the needed part is more than 40%, and the length to diameter ratio of the expansion regionis more than 3�0. It is very hard to manufacture this kind of ultra⁃thin⁃wall, curved axis and large expansion ratio tubular part without fracture and wrinkles. The success of the process is highly dependent on useful wrinkles with appropriate internal pressure and axial feeding. A simplified finite element model and a theoretical model are used for detecting the deformation behavior and forming laws. Further study results demonstrate that the useful wrinkles do not appear at the same time and middle⁃wrinkles need bigger axial force than tube⁃end⁃wrinkles and feeding⁃wrinkles. The wrinkles can transfer bigger axial force after its wave peak has come into contact with the die inner surface. The thickness thinning rate of the element at the peak is bigger than that at the trough. With the increase of the axial and hoop stress ratio, the critical buckling stress also increases. Microstructure examination results show that the grain size in the maximum thinning zone has been stretched and refined after the large deformation and annealing treatment. The process is feasible and the finished part is qualified.

  1. GPS deformation related to the Mw 7.3, 2014, Papanoa earthquake (Mexico) reveals the aseismic behavior of the Guerrero seismic gap

    Science.gov (United States)

    Gualandi, A.; Perfettini, H.; Radiguet, M.; Cotte, N.; Kostoglodov, V.

    2017-06-01

    We present the study of 21 continuous GPS (cGPS) stations in Mexico during the time interval that goes from 1 October 2013 to 31 December 2014. The area under investigation produced a slow slip event (SSE) that started in February 2014 and lasted at least until December 2014. Superimposed on this transient signal, the Mw7.3 Papanoa earthquake struck the region on 18 April 2014 and affected multiple stations. Thanks to an independent component analysis (ICA) technique we are able to separate the postseismic deformation associated with this earthquake from the deformation related to the ongoing SSE. We infer the slip distributions associated with the three tectonically related processes: the coseismic and postseismic slip and the SSE. The inferred postseismic slip distribution reduces the amount of slip related to the SSE in the updip portion of the slab. The moment released by the postseismic processes (afterslip and aftershocks) is estimated to be [8.06 ± 0.24] × 1019 Nm, equivalent to [71 ± 4]% of the moment associated with the main shock. More than 88% of the postseismic moment is released aseismically and the afterslip spatially correlates with the Guerrero seismic gap, suggesting that the region is controlled by stable sliding behavior and rate-strengthening frictional properties.

  2. Deformation and Fracture of Shale at the Nanoscale

    Science.gov (United States)

    Bennett, K. C.; Borja, R. I.

    2013-12-01

    The deformation and fracture properties of shales depend on the mechanical properties of their basic constituents, including the solid clay particles, inclusions such as silt and organics, and the multi-scale porosity comprised of existing micro-fractures and the nano-scale porosity of the porous clay matrix. A great deal of understanding of the overall macroscopic (field scale) mechanical properties of shales can be gained by studying the deformation and fracture properties of these constituents along with their composite behavior, i.e., the mechanisms of deformation and fracture of shale. This project builds upon our recently acquired ability to image with fixed ion beam scanning electron microscopy (FIB-SEM) the 3D geometry of a porous shale sample to nanometer resolution, as well as to test this sample on a nanoindenter at both the particle and composite scales, in order to develop a 3D mechanistic model to interpret the results of nanoindentation tests. The pore-scale study considers the intrinsic deformation and fracture properties of clay particles, and the effect of silt inclusions and particle packing into an anisotropic composite matrix. The analysis accounts for anisotropic and heterogeneous shale elasticity, plasticity, damage, and fissility. A finite element (FE) model is being developed which uses a recently developed finite deformation crystal plasticity algorithm and an enhanced FE method for capturing strong discontinuity. The model aims to capture the effects of the particle elasticity, plastic yielding, and the damage induced by the indenter, including the fracturing and chipping within the mineral grains and around the perimeter of the indent. Anisotropy of fracture properties is examined with respect to delamination of the clay matrix in the bed-parallel direction and to breaking of plate-like clay particles. The ultimate goal of this research is to establish a framework for investigating the poromechanical properties of shale at the nano

  3. Understanding the Pulsar High Energy Emission: Macroscopic and Kinetic Models

    Science.gov (United States)

    Kalapotharakos, Constantinos; Brambilla, Gabriele; Timokhin, Andrey; Kust Harding, Alice; Kazanas, Demos

    2017-08-01

    Pulsars are extraordinary objects powered by the rotation of magnetic fields of order 10^8, 10^12G anchored onto neutron stars and rotating with periods 10^(-3)-10s. These fields mediate the conversion of their rotational energy into MHD winds and at the same time accelerate particles to energies sufficiently high to produce GeV photons. Fermi, since its launch in 2008, has established several trends among the observed gamma-ray pulsar properties playing a catalytic role in the current modeling of the high energy emission in pulsar magnetospheres. We judiciously use the guidance provided by the Fermi data to yield meaningful constraints on the macroscopic parameters of our global dissipative pulsar magnetosphere models. Our FIDO (Force-Free Inside, Dissipative Outside) models indicate that the dissipative regions lie outside the light cylinder near the equatorial current sheet. Our models reproduce the light-curve phenomenology while a detailed comparison of the model spectral properties with those observed by Fermi reveals the dependence of the macroscopic conductivity parameter on the spin-down rate providing a unique insight into the understanding of the physical mechanisms behind the high-energy emission in pulsar magnetospheres. Finally, we further exploit these important results by building self-consistent 3D global kinetic particle-in-cell (PIC) models which, eventually, provide the dependence of the macroscopic parameter behavior (e.g. conductivity) on the microphysical properties (e.g. particle multiplicities, particle injection rates). Our PIC models provide field structures and particle distributions that are not only consistent with each other but also able to reproduce a broad range of the observed gamma-ray phenomenology (light curves and spectral properties) of both young and millisecond pulsars.

  4. Macroscopic quantum mechanics in a classical spacetime.

    Science.gov (United States)

    Yang, Huan; Miao, Haixing; Lee, Da-Shin; Helou, Bassam; Chen, Yanbei

    2013-04-26

    We apply the many-particle Schrödinger-Newton equation, which describes the coevolution of a many-particle quantum wave function and a classical space-time geometry, to macroscopic mechanical objects. By averaging over motions of the objects' internal degrees of freedom, we obtain an effective Schrödinger-Newton equation for their centers of mass, which can be monitored and manipulated at quantum levels by state-of-the-art optomechanics experiments. For a single macroscopic object moving quantum mechanically within a harmonic potential well, its quantum uncertainty is found to evolve at a frequency different from its classical eigenfrequency-with a difference that depends on the internal structure of the object-and can be observable using current technology. For several objects, the Schrödinger-Newton equation predicts semiclassical motions just like Newtonian physics, yet quantum uncertainty cannot be transferred from one object to another.

  5. Macroscopic Invisibility Cloaking of Visible Light

    CERN Document Server

    Chen, Xianzhong; Zhang, Jingjing; Jiang, Kyle; Pendry, John B; Zhang, Shuang

    2010-01-01

    Invisibility cloaks of light, which used to be confined to the imagination, have now been turned into a scientific reality, thanks to the enabling theoretical tools of transformation optics and conformal mapping. Inspired by those theoretical works, the experimental realisation of electromagnetic invisibility cloaks has been reported at various electromagnetic frequencies. All the invisibility cloaks demonstrated thus far, however, have relied on nano- or micro-fabricated artificial composite materials with spatially varying electromagnetic properties, which limit the size of the cloaked region to a few wavelengths. Here we report realisation of a macroscopic volumetric invisibility cloak constructed from natural birefringent crystals. The cloak operates at visible frequencies and is capable of hiding three-dimensional objects of the scale of centimetres and millimetres. Our work opens avenues for future applications with macroscopic cloaking devices.

  6. Macroscopic spin and charge transport theory

    Institute of Scientific and Technical Information of China (English)

    Li Da-Fang; Shi Jun-Ren

    2009-01-01

    According to the general principle of non-equilibrium thermodynamics, we propose a set of macroscopic transport equations for the spin transport and the charge transport. In particular, the spin torque is introduced as a generalized 'current density' to describe the phenomena associated with the spin non-conservation in a unified framework. The Einstein relations and the Onsager relations between different transport phenomena are established. Specifically, the spin transport properties of the isotropic non-magnetic and the isotropic magnetic two-dimensional electron gases are fully described by using this theory, in which only the macroscopic-spin-related transport phenomena allowed by the symmetry of the system are taken into account.

  7. Macroscopic entrainment of periodically forced oscillatory ensembles.

    Science.gov (United States)

    Popovych, Oleksandr V; Tass, Peter A

    2011-03-01

    Large-amplitude oscillations of macroscopic neuronal signals, such as local field potentials and electroencephalography or magnetoencephalography signals, are commonly considered as being generated by a population of mutually synchronized neurons. In a computational study in generic networks of phase oscillators and bursting neurons, however, we show that this common belief may be wrong if the neuronal population receives an external rhythmic input. The latter may stem from another neuronal population or an external, e.g., sensory or electrical, source. In that case the population field potential may be entrained by the rhythmic input, whereas the individual neurons are phase desynchronized both mutually and with their field potential. Intriguingly, the corresponding large-amplitude oscillations of the population mean field are generated by pairwise desynchronized neurons oscillating at frequencies shifted far away from the frequency of the macroscopic field potential.

  8. Adsorption modeling for macroscopic contaminant dispersal analysis

    Energy Technology Data Exchange (ETDEWEB)

    Axley, J.W.

    1990-05-01

    Two families of macroscopic adsorption models are formulated, based on fundamental principles of adsorption science and technology, that may be used for macroscopic (such as whole-building) contaminant dispersal analysis. The first family of adsorption models - the Equilibrium Adsorption (EA) Models - are based upon the simple requirement of equilibrium between adsorbent and room air. The second family - the Boundary Layer Diffusion Controlled Adsorption (BLDC) Models - add to the equilibrium requirement a boundary layer model for diffusion of the adsorbate from the room air to the adsorbent surface. Two members of each of these families are explicitly discussed, one based on the linear adsorption isotherm model and the other on the Langmuir model. The linear variants of each family are applied to model the adsorption dynamics of formaldehyde in gypsum wall board and compared to measured data.

  9. Macroscopic Invisible Cloak for Visible Light

    CERN Document Server

    Zhang, Baile; Liu, Xiaogang; Barbastathis, George

    2011-01-01

    Invisibility cloaks, a subject that usually occurs in science fiction and myths, have attracted wide interest recently because of their possible realization. The biggest challenge to true invisibility is known to be the cloaking of a macroscopic object in the broad range of wavelengths visible to the human eye. Here we experimentally solve this problem by incorporating the principle of transformation optics into a conventional optical lens fabrication with low-cost materials and simple manufacturing techniques. A transparent cloak made of two pieces of calcite is created. This cloak is able to conceal a macroscopic object with a maximum height of 2 mm, larger than 3500 free-space-wavelength, inside a transparent liquid environment. Its working bandwidth encompassing red, green and blue light is also demonstrated.

  10. The effect of inclination angle on the plastic deformation behavior of bicrystalline silver nanowires with Σ3 asymmetric tilt grain boundaries

    Science.gov (United States)

    Yuan, Lin; Jing, Peng; Shan, Debin; Guo, Bin

    2017-01-01

    Atomistic simulations were used to investigate the plastic deformation behavior of bicrystalline silver nanowires with Σ3 asymmetric tilt grain boundaries at 0.1 K. The calculated grain boundary energies of Σ3 asymmetric tilt grain boundaries corresponded well with the energies measured in experiments and predicted by the theoretical description. The Σ3 asymmetric tilt grain boundaries with low inclination angles were composed of a replication of twin boundary segments separated by small ledges. The results demonstrated that the combination effect of Schmid factor and non-Schmid factors could explain dislocations emission into grain 1 only in models with low inclination angles (Ф nanocrystalline materials and provide insights into the synthesis of nanocrystalline materials with superior strength and ductility.

  11. Deformation behavior of Re alloyed Mo thin films on flexible substrates: In situ fragmentation analysis supported by first-principles calculations.

    Science.gov (United States)

    Jörg, Tanja; Music, Denis; Hauser, Filipe; Cordill, Megan J; Franz, Robert; Köstenbauer, Harald; Winkler, Jörg; Schneider, Jochen M; Mitterer, Christian

    2017-08-07

    A major obstacle in the utilization of Mo thin films in flexible electronics is their brittle fracture behavior. Within this study, alloying with Re is explored as a potential strategy to improve the resistance to fracture. The sputter-deposited Mo1-xRex films (with 0 ≤ x ≤ 0.31) were characterized in terms of structural and mechanical properties, residual stresses as well as electrical resistivity. Their deformation behavior was assessed by straining 50 nm thin films on polyimide substrates in uniaxial tension, while monitoring crack initiation and propagation in situ by optical microscopy and electrical resistance measurements. A significant toughness enhancement occurs with increasing Re content for all body-centered cubic solid solution films (x ≤ 0.23). However, at higher Re concentrations (x > 0.23) the positive effect of Re is inhibited due to the formation of dual-phase films with the additional close packed A15 Mo3Re phase. The mechanisms responsible for the observed toughness behavior are discussed based on experimental observations and electronic structure calculations. Re gives rise to both increased plasticity and bond strengthening in these Mo-Re solid solutions.

  12. Macroscopic Quantum Resonators (MAQRO): 2015 update

    Energy Technology Data Exchange (ETDEWEB)

    Kaltenbaek, Rainer [University of Vienna, Vienna Center for Quantum Science and Technology, Vienna (Austria); Aspelmeyer, Markus; Kiesel, Nikolai [University of Vienna, Vienna Center for Quantum Science and Technology, Vienna (Austria); Barker, Peter F.; Bose, Sougato [University College London, Department of Physics and Astronomy, London (United Kingdom); Bassi, Angelo [University of Trieste, Department of Physics, Trieste (Italy); INFN - Trieste Section, Trieste (Italy); Bateman, James [University of Swansea, Department of Physics, College of Science, Swansea (United Kingdom); Bongs, Kai; Cruise, Adrian Michael [University of Birmingham, School of Physics and Astronomy, Birmingham (United Kingdom); Braxmaier, Claus [University of Bremen, Center of Applied Space Technology and Micro Gravity (ZARM), Bremen (Germany); Institute of Space Systems, German Aerospace Center (DLR), Bremen (Germany); Brukner, Caslav [University of Vienna, Vienna Center for Quantum Science and Technology, Vienna (Austria); Austrian Academy of Sciences, Institute of Quantum Optics and Quantum Information (IQOQI), Vienna (Austria); Christophe, Bruno; Rodrigues, Manuel [The French Aerospace Lab, ONERA, Chatillon (France); Chwalla, Michael; Johann, Ulrich [Airbus Defence and Space GmbH, Immenstaad (Germany); Cohadon, Pierre-Francois; Heidmann, Antoine; Lambrecht, Astrid; Reynaud, Serge [ENS-PSL Research University, Laboratoire Kastler Brossel, UPMC-Sorbonne Universites, CNRS, College de France, Paris (France); Curceanu, Catalina [Laboratori Nazionali di Frascati dell' INFN, Frascati (Italy); Dholakia, Kishan; Mazilu, Michael [University of St. Andrews, School of Physics and Astronomy, St. Andrews (United Kingdom); Diosi, Lajos [Wigner Research Center for Physics, P.O. Box 49, Budapest (Hungary); Doeringshoff, Klaus; Peters, Achim [Humboldt-Universitaet zu Berlin, Institut fuer Physik, Berlin (Germany); Ertmer, Wolfgang; Rasel, Ernst M. [Leibniz Universitaet Hannover, Institut fuer Quantenoptik, Hannover (Germany); Gieseler, Jan; Novotny, Lukas; Rondin, Loic [ETH Zuerich, Photonics Laboratory, Zuerich (Switzerland); Guerlebeck, Norman; Herrmann, Sven; Laemmerzahl, Claus [University of Bremen, Center of Applied Space Technology and Micro Gravity (ZARM), Bremen (Germany); Hechenblaikner, Gerald [Airbus Defence and Space GmbH, Immenstaad (Germany); European Southern Observatory (ESO), Garching bei Muenchen (Germany); Hossenfelder, Sabine [KTH Royal Institute of Technology and Stockholm University, Nordita, Stockholm (Sweden); Kim, Myungshik [Imperial College London, QOLS, Blackett Laboratory, London (United Kingdom); Milburn, Gerard J. [University of Queensland, ARC Centre for Engineered Quantum Systems, Brisbane (Australia); Mueller, Holger [University of California, Department of Physics, Berkeley, CA (United States); Paternostro, Mauro [Queen' s University, Centre for Theoretical Atomic, Molecular and Optical Physics, School of Mathematics and Physics, Belfast (United Kingdom); Pikovski, Igor [Harvard-Smithsonian Center for Astrophysics, ITAMP, Cambridge, MA (United States); Pilan Zanoni, Andre [Airbus Defence and Space GmbH, Immenstaad (Germany); CERN - European Organization for Nuclear Research, EN-STI-TCD, Geneva (Switzerland); Riedel, Charles Jess [Perimeter Institute for Theoretical Physics, Waterloo, ON (Canada); Roura, Albert [Universitaet Ulm, Institut fuer Quantenphysik, Ulm (Germany); Schleich, Wolfgang P. [Universitaet Ulm, Institut fuer Quantenphysik, Ulm (Germany); Texas A and M University Institute for Advanced Study (TIAS), Institute for Quantum Science and Engineering (IQSE), and Department of Physics and Astronomy, College Station, TX (United States); Schmiedmayer, Joerg [Vienna University of Technology, Vienna Center for Quantum Science and Technology, Institute of Atomic and Subatomic Physics, Vienna (Austria); Schuldt, Thilo [Institute of Space Systems, German Aerospace Center (DLR), Bremen (Germany); Schwab, Keith C. [California Institute of Technology, Applied Physics, Pasadena, CA (United States)

    2016-12-15

    Do the laws of quantum physics still hold for macroscopic objects - this is at the heart of Schroedinger's cat paradox - or do gravitation or yet unknown effects set a limit for massive particles? What is the fundamental relation between quantum physics and gravity? Ground-based experiments addressing these questions may soon face limitations due to limited free-fall times and the quality of vacuum and microgravity. The proposed mission Macroscopic Quantum Resonators (MAQRO) may overcome these limitations and allow addressing such fundamental questions. MAQRO harnesses recent developments in quantum optomechanics, high-mass matter-wave interferometry as well as state-of-the-art space technology to push macroscopic quantum experiments towards their ultimate performance limits and to open new horizons for applying quantum technology in space. The main scientific goal is to probe the vastly unexplored 'quantum-classical' transition for increasingly massive objects, testing the predictions of quantum theory for objects in a size and mass regime unachievable in ground-based experiments. The hardware will largely be based on available space technology. Here, we present the MAQRO proposal submitted in response to the 4th Cosmic Vision call for a medium-sized mission (M4) in 2014 of the European Space Agency (ESA) with a possible launch in 2025, and we review the progress with respect to the original MAQRO proposal for the 3rd Cosmic Vision call for a medium-sized mission (M3) in 2010. In particular, the updated proposal overcomes several critical issues of the original proposal by relying on established experimental techniques from high-mass matter-wave interferometry and by introducing novel ideas for particle loading and manipulation. Moreover, the mission design was improved to better fulfill the stringent environmental requirements for macroscopic quantum experiments. (orig.)

  13. A macroscopic approach to creating exotic matter

    OpenAIRE

    Ridgely, C. T.

    2000-01-01

    Herein the Casimir effect is used to present a simple macroscopic view on creating exotic matter. The energy arising between two nearly perfectly conducting parallel plates is shown to become increasingly negative as the plate separation is reduced. It is proposed that the Casimir energy appears increasingly negative simply because the vacuum electromagnetic zero-point field performs positive work in pushing the plates together, transforming field energy into kinetic energy of the plates. Nex...

  14. Shot noise in linear macroscopic resistors

    OpenAIRE

    Gomila Lluch, Gabriel; Pennetta, C.; Reggiani, L.; Ferrari, G; Sampietro, M.; G. Bertuccio(Politecnico di Milano, Italy)

    2004-01-01

    We report on direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. The present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devi...

  15. Shot Noise in Linear Macroscopic Resistors

    Science.gov (United States)

    Gomila, G.; Pennetta, C.; Reggiani, L.; Sampietro, M.; Ferrari, G.; Bertuccio, G.

    2004-06-01

    We report on direct experimental evidence of shot noise in a linear macroscopic resistor. The origin of the shot noise comes from the fluctuation of the total number of charge carriers inside the resistor associated with their diffusive motion under the condition that the dielectric relaxation time becomes longer than the dynamic transit time. The present results show that neither potential barriers nor the absence of inelastic scattering are necessary to observe shot noise in electronic devices.

  16. Macroscopic Objects, Intrinsic Spin, and Lorentz Violation

    CERN Document Server

    Atkinson, David W; Tasson, Jay D

    2013-01-01

    The framework of the Standard-Model Extension (SME) provides a relativistic quantum field theory for the study of Lorentz violation. The classical, nonrelativistic equations of motion can be extracted as a limit that is useful in various scenarios. In this work, we consider the effects of certain SME coefficients for Lorentz violation on the motion of macroscopic objects having net intrinsic spin in the classical, nonrelativistic limit.

  17. Active Polar Two-Fluid Macroscopic Dynamics

    Science.gov (United States)

    Pleiner, Harald; Svensek, Daniel; Brand, Helmut R.

    2014-03-01

    We study the dynamics of systems with a polar dynamic preferred direction. Examples include the pattern-forming growth of bacteria (in a solvent, shoals of fish (moving in water currents), flocks of birds and migrating insects (flying in windy air). Because the preferred direction only exists dynamically, but not statically, the macroscopic variable of choice is the macroscopic velocity associated with the motion of the active units. We derive the macroscopic equations for such a system and discuss novel static, reversible and irreversible cross-couplings connected to this second velocity. We find a normal mode structure quite different compared to the static descriptions, as well as linear couplings between (active) flow and e.g. densities and concentrations due to the genuine two-fluid transport derivatives. On the other hand, we get, quite similar to the static case, a direct linear relation between the stress tensor and the structure tensor. This prominent ``active'' term is responsible for many active effects, meaning that our approach can describe those effects as well. In addition, we also deal with explicitly chiral systems, which are important for many active systems. In particular, we find an active flow-induced heat current specific for the dynamic chiral polar order.

  18. 3D printed, bio-inspired prototypes and analytical models for structured suture interfaces with geometrically-tuned deformation and failure behavior

    Science.gov (United States)

    Lin, Erica; Li, Yaning; Ortiz, Christine; Boyce, Mary C.

    2014-12-01

    Geometrically structured interfaces in nature possess enhanced, and often surprising, mechanical properties, and provide inspiration for materials design. This paper investigates the mechanics of deformation and failure mechanisms of suture interface designs through analytical models and experiments on 3D printed polymer physical prototypes. Suture waveforms with generalized trapezoidal geometries (trapezoidal, rectangular, anti-trapezoidal, and triangular) are studied and characterized by several important geometric parameters: the presence or absence of a bonded tip region, the tip angle, and the geometry. It is shown that a wide range (in some cases as great as an order of magnitude) in stiffness, strength, and toughness is achievable dependent on tip bonding, tip angle, and geometry. Suture interfaces with a bonded tip region exhibit a higher initial stiffness due to the greater load bearing by the skeletal teeth, a double peak in the stress-strain curve corresponding to the failure of the bonded tip and the failure of the slanted interface region or tooth, respectively, and an additional failure and toughening mechanism due to the failure of the bonded tip. Anti-trapezoidal geometries promote the greatest amplification of properties for suture interfaces with a bonded tip due the large tip interface area. The tip angle and geometry govern the stress distributions in the teeth and the ratio of normal to shear stresses in the interfacial layers, which together determine the failure mechanism of the interface and/or the teeth. Rectangular suture interfaces fail by simple shearing of the interfaces. Trapezoidal and triangular suture interfaces fail by a combination of shear and tensile normal stresses in the interface, leading to plastic deformation, cavitation events, and subsequent stretching of interface ligaments with mostly elastic deformation in the teeth. Anti-trapezoidal suture interfaces with small tip angles have high stress concentrations in the teeth

  19. Formation and subdivision of deformation structures during plastic deformation

    DEFF Research Database (Denmark)

    Jakobsen, B.; Poulsen, H.F.; Lienert, U.;

    2006-01-01

    During plastic deformation of metals and alloys, dislocations arrange in ordered patterns. How and when these self-organization processes take place have remained elusive, because in situ observations have not been feasible. We present an x-ray diffraction method that provided data on the dynamics...... of individual, deeply embedded dislocation structures. During tensile deformation of pure copper, dislocation-free regions were identified. They showed an unexpected intermittent dynamics, for example, appearing and disappearing with proceeding deformation and even displaying transient splitting behavior....... Insight into these processes is relevant for an understanding of the strength and work-hardening of deformed materials....

  20. Effects of High Rate Shear on the Microstructure and Deformation and Fracture Behavior of Two High Strength Steels

    Science.gov (United States)

    1989-04-01

    Nickel (Ni) content between the steels. As shown in Table 1, the Q&T steel had 5% Ni while the DQ steel had only 1% Ni. Nickel in alpha iron has been...Yield and Fracture Behavior of Alpha Iron ," Trans. Met. Soc. of AIME, Vol. 242, pp. 306 - 314, February, 1968 Kalthoff, J.F. and Winkler, S., "Fracture

  1. Two-phase flow properties in aperture-based fractures under normal deformation conditions: Analytical approach and numerical simulation

    Science.gov (United States)

    Ye, Zuyang; Liu, Hui-Hai; Jiang, Qinghui; Liu, Yanzhang; Cheng, Aiping

    2017-02-01

    A systematic method has been proposed to estimate the two-phase flow properties of horizontal fractures under normal deformation condition. Based on Gaussian aperture distributions and the assumption of local parallel plate model, a simple model was obtained in closed form to predict the capillary pressure-saturation relationships for both wetting and non-wetting phases. Three conceptual models were also developed to characterize the relative permeability behaviors. In order to investigate the effect of normal deformation on two-phase flow properties, the normal deformation could be represented with the maximum void space closure on the basis of penetration model. A rigorous successive random addition (SRA) method was used to generate the aperture-based fractures and a numerical approach based on invasion percolation (IP) model was employed to model capillary-dominated displacements between wetting and non-wetting phases. The proposed models were partially verified by a laboratory dataset and numerical calculations without consideration of deformation. Under large normal deformations, it was found that the macroscopic model is in better agreement with simulated observations. The simulation results demonstrated that the two-phase flow properties including the relationships between capillary pressure, relative permeability and saturation, phase interference, phase structures, residual-saturation-rated parameters and tortuosity factor, were highly sensitive to the spatial correlation of aperture distribution and normal deformation.

  2. Evolution and distribution of macroscopic gas channels in an overburden strata

    Institute of Scientific and Technical Information of China (English)

    Liu; Hongtao; Ma; Nianjie; Ma; Wang; Ren; Guoqiang

    2012-01-01

    The evolution of gas bearing channels in the roof,and their spatial distribution,was studied.A complete consideration of gas flow changes through the stress-strain changes in the roof near a working face is made.The theoretical abutment pressure distribution using displacement monitors and borehole visual recording instruments allow a theoretical analysis.Field test research determined the conditions for formation of macroscopic gas channels.These appear along the working face roof,normally distributed to it.These results show that the coal rock stratification becomes a macroscopic gas channel boundary if its deformation is less than the lower layer,or greater than the layer above it.At the same time the stability is greater than the distance from the roof for hanging dew conditions.The working face advances and the roof gas channels experience a cycle of development.Microscopic channels dominate the initial stage then macroscopic gas channels form,develop,and close.The evolution of the macroscopic channels depends on the ratio between the distances from the new compaction area in the goaf to the initial stress area in front of the working face.The amount of daily advance of the face also affects channel development.The experimental observations in one mining area showed that the main gas channels are located about 2 and 6.2 m above the lower surface of the roof and that they have an evolution period 7 to 11 days long.

  3. Energetics of macroscopic helical domain in different tube geometries and loading

    Directory of Open Access Journals (Sweden)

    Sun Q.P.

    2010-06-01

    Full Text Available Superelastic NiTi polycrystalline shape memory alloy tubes, when subject to slow quasistatic stretching, transform to a high strain phase by the formation and growth of a macroscopic helix-shaped domain as deformation progresses. This paper performed an experimental study on the effects of the external applied nominal strain and the tube geometry (tube radius R, wall-thickness h and length L on the helical domains in isothermal stretching of the tubes. The evolution of the macroscopic domains with the applied strain in different tube geometries are quantified by in-situ optical measurement. We demonstrate that the equilibrium shape of the macroscopic helical domain and its evolution are governed by the competition between the domain front energy and the elastic-misfit bending strain energy of the tube system. The former favors a short helical domain, while the latter favors a long slim helical domain. The experimental results provided basic physical and experimental foundations for further modelling and quantification of the macroscopic domain morphology evolution in tube geometries.

  4. Simulation of the effects of voids on the deformation behavior of bulk amorphous alloys%含孔洞大块非晶合金变形行为的数值研究

    Institute of Scientific and Technical Information of China (English)

    徐剑晴; 王宇

    2011-01-01

    建立能够描述静水压力影响和塑性体积膨胀的率相关的大块非晶合金本构模型.通过编写ABAQUS材料用户子程序VUMAT,对含不同形态孔洞的Zr基大块非晶合金的变形行为进行有限元分析,并对其细观变化规律进行研究.%A rate-dependent constitutive model for the deformation behavior of amorphous alloys with the effects of hydrostatic-pressure sensitivity and plastically-dilatancy was developed. The constitutive model was implemented in a finite element analysis to study the effects of the voids on the deformation behavior of bulk amorphous alloys by writing a user subroutine in ABAQUS/VUMAT. The mesoscope evolvement law of the deformation was also studied.

  5. Deformation mechanisms in experimentally deformed Boom Clay

    Science.gov (United States)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures

  6. A Bloch-Torrey Equation for Diffusion in a Deforming Media

    Energy Technology Data Exchange (ETDEWEB)

    Rohmer, Damien; Gullberg, Grant T.

    2006-12-29

    Diffusion Tensor Magnetic Resonance Imaging (DTMRI)technique enables the measurement of diffusion parameters and therefore,informs on the structure of the biological tissue. This technique isapplied with success to the static organs such as brain. However, thediffusion measurement on the dynamically deformable organs such as thein-vivo heart is a complex problem that has however a great potential inthe measurement of cardiac health. In order to understand the behavior ofthe Magnetic Resonance (MR)signal in a deforming media, the Bloch-Torreyequation that leads the MR behavior is expressed in general curvilinearcoordinates. These coordinates enable to follow the heart geometry anddeformations through time. The equation is finally discretized andpresented in a numerical formulation using implicit methods, in order toget a stable scheme that can be applied to any smooth deformations.Diffusion process enables the link between the macroscopic behavior ofmolecules and themicroscopic structure in which they evolve. Themeasurement of diffusion in biological tissues is therefore of majorimportance in understanding the complex underlying structure that cannotbe studied directly. The Diffusion Tensor Magnetic ResonanceImaging(DTMRI) technique enables the measurement of diffusion parametersand therefore provides information on the structure of the biologicaltissue. This technique has been applied with success to static organssuch as the brain. However, diffusion measurement of dynamicallydeformable organs such as the in-vivo heart remains a complex problem,which holds great potential in determining cardiac health. In order tounderstand the behavior of the magnetic resonance (MR) signal in adeforming media, the Bloch-Torrey equation that defines the MR behavioris expressed in general curvilinear coordinates. These coordinates enableus to follow the heart geometry and deformations through time. Theequation is finally discretized and presented in a numerical formulationusing

  7. Contracture deformity

    Science.gov (United States)

    Deformity - contracture ... Contracture can be caused by any of the following: Brain and nervous system disorders, such as cerebral ... Follow your health care provider's instructions for treating contracture at home. Treatments may include: Doing exercises and ...

  8. Simulation of deformation twins and deformation texture in an AZ31 Mg alloy under uniaxial compression

    Energy Technology Data Exchange (ETDEWEB)

    Choi, S.-H. [Department of Materials Science and Metallurgical Engineering, Sunchon National University, Sunchon 540-742 (Korea, Republic of)]. E-mail: shihoon@sunchon.ac.kr; Shin, E.J. [Korea Atomic Energy Research Institute, Neutron Physics Department, Daejeon 305-600 (Korea, Republic of); Seong, B.S. [Korea Atomic Energy Research Institute, Neutron Physics Department, Daejeon 305-600 (Korea, Republic of)

    2007-07-15

    To investigate deformation twins and the evolution of deformation texture during plastic deformation, uniaxial compression tests on a hot-rolled AZ31 Mg alloy were carried out at 200 deg. C. Cylindrical specimens were then compressed in both the rolling and the normal directions. The findings revealed that texture evolution, work hardening and macroscopic anisotropy are strongly dependent on the loading direction. Electron backscattered diffraction analysis was used to examine the orientation of parent grains and twin bands in the AZ31 Mg alloy under uniaxial compression. A viscoplastic self-consistent model (VPSC) was theoretically employed to calculate the relative activities of slip and twin systems in polycrystalline hexagonal aggregates under uniaxial compression. Each deformed grain exhibited an independent number and type of twin variants under uniaxial compression. Neutron diffraction was used to measure the macroscopic texture of the AZ31 Mg alloy. The VPSC model was used to simulate texture evolution, work hardening and macroscopic anisotropy during the uniaxial compression. A modified predominant twin reorientation (PTR) scheme was suggested to explain the gradual increase in twin volume in deformed grains.

  9. Monotonic and cyclic deformation behavior of MIG-CMT welded and heat-treated joints of aluminum cast and wrought alloys

    Energy Technology Data Exchange (ETDEWEB)

    Kantehm, Matthias; Soeker, Marcus; Krupp, Ulrich; Michels, Wilhelm [Faculty of Engineering and Computer Science, Institute of Materials Design and Structural Integrity, University of Applied Sciences Osnabrueck, 49009 Osnabrueck (Germany)

    2012-10-15

    While the fatigue behavior of die cast aluminum as well as welded aluminum wrought alloys have been subject of several studies, no systematic work has been carried out on hybrid structures made as a combination of welded sand castings and wrought alloys. Aim of the present study is to correlate the monotonic and cyclic deformation behavior of thin sheet welded joints with the microstructure in the heat affected zone of the material combination sand cast EN AC-Al Si7Mg0.3 and wrought alloy EN AW-Al Si1MgMn (EN AW-6082). The metal sheets were welded using a metal inert gas cold metal transfer process under variation of the welding gap, the heat treatment parameters, as well as the surface finishes. It was demonstrated by Woehler diagrams based on bending fatigue tests that the fatigue life could be increased for the welded and heat treated specimens as compared to the as-received cast specimens. By means of optical microscopy this effect was attributed to microstructural changes due to the optimized welding and heat treatment process. A detailed analysis of the mechanical tests was possible by the application of an optical 3D strain analysis. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Data related to cyclic deformation and fatigue behavior of direct laser deposited Ti-6Al-4V with and without heat treatment.

    Science.gov (United States)

    Sterling, Amanda J; Torries, Brian; Shamsaei, Nima; Thompson, Scott M

    2016-03-01

    Data is presented describing the strain-controlled, fully-reversed uniaxial cyclic deformation and fatigue behavior of Ti-6Al-4V specimens additively manufactured via Laser Engineered Net Shaping (LENS) - a Direct Laser Deposition (DLD) process. The data was collected by performing multiple fatigue tests on specimens with various microstructural states/conditions, i.e. in their 'as-built', annealed (below the beta transus temperature), or heat treated (above the beta transus temperature) condition. Such data aids in characterizing the mechanical integrity and fatigue resistance of DLD parts. Data presented herein also allows for elucidating the strong microstructure coupling of the fatigue behavior of DLD Ti-6Al-4V, as the data trends were found to vary with material condition (i.e. as-built, annealed or heat treated) [1]. This data is of interest to the additive manufacturing and fatigue scientific communities, as well as the aerospace and biomedical industries, since additively-manufactured parts cannot be reliably deployed for public use, until their mechanical properties are understood with high certainty.

  11. Data related to cyclic deformation and fatigue behavior of direct laser deposited Ti–6Al–4V with and without heat treatment

    Directory of Open Access Journals (Sweden)

    Amanda J. Sterling

    2016-03-01

    Full Text Available Data is presented describing the strain-controlled, fully-reversed uniaxial cyclic deformation and fatigue behavior of Ti–6Al–4V specimens additively manufactured via Laser Engineered Net Shaping (LENS – a Direct Laser Deposition (DLD process. The data was collected by performing multiple fatigue tests on specimens with various microstructural states/conditions, i.e. in their ‘as-built’, annealed (below the beta transus temperature, or heat treated (above the beta transus temperature condition. Such data aids in characterizing the mechanical integrity and fatigue resistance of DLD parts. Data presented herein also allows for elucidating the strong microstructure coupling of the fatigue behavior of DLD Ti–6Al–4V, as the data trends were found to vary with material condition (i.e. as-built, annealed or heat treated [1]. This data is of interest to the additive manufacturing and fatigue scientific communities, as well as the aerospace and biomedical industries, since additively-manufactured parts cannot be reliably deployed for public use, until their mechanical properties are understood with high certainty.

  12. Rainbow correlation imaging with macroscopic twin beam

    Science.gov (United States)

    Allevi, Alessia; Bondani, Maria

    2017-06-01

    We present the implementation of a correlation-imaging protocol that exploits both the spatial and spectral correlations of macroscopic twin-beam states generated by parametric downconversion. In particular, the spectral resolution of an imaging spectrometer coupled to an EMCCD camera is used in a proof-of-principle experiment to encrypt and decrypt a simple code to be transmitted between two parties. In order to optimize the trade-off between visibility and resolution, we provide the characterization of the correlation images as a function of the spatio-spectral properties of twin beams generated at different pump power values.

  13. Fingerprint Feature Extraction Based on Macroscopic Curvature

    Institute of Scientific and Technical Information of China (English)

    Zhang Xiong; He Gui-ming; Zhang Yun

    2003-01-01

    In the Automatic Fingerprint Identification System (AFIS), extracting the feature of fingerprint is very important. The local curvature of ridges of fingerprint is irregular, so people have the barrier to effectively extract the fingerprint curve features to describe fingerprint. This article proposes a novel algorithm; it embraces information of few nearby fingerprint ridges to extract a new characteristic which can describe the curvature feature of fingerprint. Experimental results show the algorithm is feasible, and the characteristics extracted by it can clearly show the inner macroscopic curve properties of fingerprint. The result also shows that this kind of characteristic is robust to noise and pollution.

  14. Fingerprint Feature Extraction Based on Macroscopic Curvature

    Institute of Scientific and Technical Information of China (English)

    Zhang; Xiong; He; Gui-Ming; 等

    2003-01-01

    In the Automatic Fingerprint Identification System(AFIS), extracting the feature of fingerprint is very important. The local curvature of ridges of fingerprint is irregular, so people have the barrier to effectively extract the fingerprint curve features to describe fingerprint. This article proposes a novel algorithm; it embraces information of few nearby fingerprint ridges to extract a new characterstic which can describe the curvature feature of fingerprint. Experimental results show the algorithm is feasible, and the characteristics extracted by it can clearly show the inner macroscopic curve properties of fingerprint. The result also shows that this kind of characteristic is robust to noise and pollution.

  15. Macroscopic Quantum Criticality in a Circuit QED

    CERN Document Server

    Wang, Y D; Nori, F; Quan, H T; Sun, C P; Liu, Yu-xi; Nori, Franco

    2006-01-01

    Cavity quantum electrodynamic (QED) is studied for two strongly-coupled charge qubits interacting with a single-mode quantized field, which is provided by a on-chip transmission line resonator. We analyze the dressed state structure of this superconducting circuit QED system and the selection rules of electromagnetic-induced transitions between any two of these dressed states. Its macroscopic quantum criticality, in the form of ground state level crossing, is also analyzed, resulting from competition between the Ising-type inter-qubit coupling and the controllable on-site potentials.

  16. Macroscopic fluctuations theory of aerogel dynamics

    CERN Document Server

    Lefevere, Raphael; Zambotti, Lorenzo

    2010-01-01

    We consider extensive deterministic dynamics made of $N$ particles modeling aerogels under a macroscopic fluctuation theory description. By using a stochastic model describing those dynamics after a diffusive rescaling, we show that the functional giving the exponential decay in $N$ of the probability of observing a given energy and current profile is not strictly convex as a function of the current. This behaviour is caused by the fact that the energy current is carried by particles which may have arbitrary low speed with sufficiently large probability.

  17. On cavitation and macroscopic behaviour of amorphous polymer-rubber blends

    Directory of Open Access Journals (Sweden)

    Naima Belayachi et al

    2008-01-01

    Full Text Available The macroscopic behaviour of rubber-modified polymethyl methacrylate (PMMA was investigated by taking into account the microdeformation mechanisms of rubber cavitation. The dependence of the macroscopic stress–strain behaviour of matrix deformation on the cavitation of rubber particles was discussed. A phenomenological elastic-viscoplastic model was used to model the behaviour of the matrix material, while the rubber particles were modelled with the hyperelasticity theory. A two-phase composite material with a periodic arrangement of reinforcing particles of a circular unit cell section was considered. Finite-element analysis was used to determine the local stresses and strains in the two-phase composite. In order to describe the cavitation of the rubber particles, a criterion of void nucleation is implemented in the finite-element (FE code. A comparison of the numerically predicted response with experimental result indicates that the numerical homogenisation analysis gives satisfactory prediction results.

  18. Chaotic Advection at the Pore Scale: Mechanisms, Upscaling and Implications for Macroscopic Transport

    CERN Document Server

    Lester, D R; Metcalfe, Guy

    2016-01-01

    The macroscopic spreading and mixing of solute plumes in saturated porous media is ultimately controlled by processes operating at the pore scale. Whilst the conventional picture of pore-scale mechanical dispersion and molecular diffusion leading to persistent hydrodynamic dispersion is well accepted, this paradigm is inherently two-dimensional (2D) in nature and neglects important three-dimensional (3D) phenomena. We discuss how the kinematics of steady 3D flow at the porescale generate chaotic advection, involving exponential stretching and folding of fluid elements,the mechanisms by which it arises and implications of microscopic chaos for macroscopic dispersion and mixing. Prohibited in steady 2D flow due to topological constraints, these phenomena are ubiquitous due to the topological complexity inherent to all 3D porous media. Consequently 3D porous media flows generate profoundly different fluid deformation and mixing processes to those of 2D flow. The interplay of chaotic advection and broad transit t...

  19. Homogenized Creep Behavior of CFRP Laminates at High Temperature

    Science.gov (United States)

    Fukuta, Y.; Matsuda, T.; Kawai, M.

    In this study, creep behavior of a CFRP laminate subjected to a constant stress is analyzed based on the time-dependent homogenization theory developed by the present authors. The laminate is a unidirectional carbon fiber/epoxy laminate T800H/#3631 manufactured by Toray Industries, Inc. Two kinds of creep analyses are performed. First, 45° off-axis creep deformation of the laminate at high temperature (100°C) is analyzed with three kinds of creep stress levels, respectively. It is shown that the present theory accurately predicts macroscopic creep behavior of the unidirectional CFRP laminate observed in experiments. Then, high temperature creep deformations at a constant creep stress are simulated with seven kinds of off-axis angles, i.e., θ = 0°, 10°, 30°, 45°, 60°, 75°, 90°. It is shown that the laminate has marked in-plane anisotropy with respect to the creep behavior.

  20. Peculiarities of the rheological behavior and structure formation of aluminum under deformation at near-solidus temperatures

    Institute of Scientific and Technical Information of China (English)

    A S Smirnov; A V Konovalov; G ABelozerov; V P Shveikin; E O Smirnova

    2016-01-01

    This paper deals with a peculiar rheological behavior of aluminum at near-solidus temperatures.It has been experimentally estab-lished that there is an inverse strain rate dependence of strain resistance at temperatures ranging between 560 and 640°C and strain rates ranging from 0.06 to 1.2 s−1. Electron backscatter diffraction analysis has shown that at temperatures ranging between 540 and 640°C and strain rates ranging from 0.06 to 0.1 s−1, the main process of softening is dynamic polygonization, resulting inin situ recrystallization. At higher strain rates, ranging between 0.8 and 1.2 s−1, and temperatures ranging between 560 and 640°C, the recovery is dynamic. This unusual behavior of the mechanism of softening and the presence of the inverse strain rate dependence of strain resistance can be explained by blocking the motion of free dislocations by foreign atoms, which occurs at strain rates ranging between 0.06 and 0.1 s−1. This process results in dislocation pile-up, thereby causingin situ recrystallization. At strain rates exceeding 0.16 s−1, there is no intensive blocking of dislocations, leading to a direct strain rate dependence of strain resistance.

  1. Bouncing droplets: a classroom experiment to visualize wave-particle duality on the macroscopic level

    Science.gov (United States)

    Sleutel, Pascal; Dietrich, Erik; Van der Veen, Jan T.; van Joolingen, Wouter R.

    2016-09-01

    This study brings a recently discovered macroscopic phenomenon with wave-particle characteristics into the classroom. The system consists of a liquid droplet levitating over a vertically shaken liquid pool. The droplets allow visualization of a wave-particle system in a directly observable way. We show how to interpret this macroscopic phenomenon and how to set up and carry out this experiment. A class of students performed single slit diffraction experiments with droplets. By scoring individual droplet trajectories students find a diffraction pattern. This pilot application in the classroom shows that students can study and discuss the wave-particle nature of the bouncing droplet experiment. The experiment therefore provides a useful opportunity to show wave-particle behavior on the macroscopic level.

  2. Spin models as microfoundation of macroscopic market models

    Science.gov (United States)

    Krause, Sebastian M.; Bornholdt, Stefan

    2013-09-01

    Macroscopic price evolution models are commonly used for investment strategies. There are first promising achievements in defining microscopic agent based models for the same purpose. Microscopic models allow a deeper understanding of mechanisms in the market than the purely phenomenological macroscopic models, and thus bear the chance for better models for market regulation. However microscopic models and macroscopic models are commonly studied separately. Here, we exemplify a unified view of a microscopic and a macroscopic market model in a case study, deducing a macroscopic Langevin equation from a microscopic spin market model closely related to the Ising model. The interplay of the microscopic and the macroscopic view allows for a better understanding and adjustment of the microscopic model, as well, and may guide the construction of agent based market models as basis of macroscopic models.

  3. Tough and Thermosensitive Poly(N-isopropylacrylamide)/Graphene Oxide Hydrogels with Macroscopically Oriented Liquid Crystalline Structures.

    Science.gov (United States)

    Zhu, Zhongcheng; Li, Yang; Xu, Hui; Peng, Xin; Chen, Ya-Nan; Shang, Cong; Zhang, Qin; Liu, Jiaqi; Wang, Huiliang

    2016-06-22

    Bulk graphene oxide (GO) nanocomposite materials with macroscopically oriented GO liquid crystalline (LC) structures exhibit interesting anisotropic properties, but their facile preparations remain challenging. This work reports for the first time the facile preparation of poly(N-isopropylacrylamide) (PNIPAM)/GO nanocomposite hydrogels with macroscopically oriented LC structures with the assistance of a flow field induced by vacuum degassing and the in situ polymerization accelerated by GO. The hydrogel prepared with a GO concentration of 5.0 mg mL(-1) exhibits macroscopically aligned LC structures, which endow the gels with anisotropic optical, mechanical properties, and dimensional changes during the phase transition. The hydrogels show dramatically enhanced tensile mechanical properties and phase transition rates. The oriented LC structures are not damaged during the phase transition of the PNIPAM/GO hydrogels, and hence their LC behavior undergoes reversible change. Moreover, highly oriented LC structures can also be formed when the gels are elongated, even for the gels which do not have macroscopically oriented LC structures. Very impressively, the oriented LC structures in the hydrogels can be permanently maintained by drying the gel samples elongated to and then kept at a constant tensile strain. The thermosensitive nature of PNIPAM and the angle-dependent nature of the macroscopically aligned GO LC structures allow the practical applications of the PNIPAM/GO hydrogels as optical switches, soft sensors, and actuators and so on.

  4. MACROSCOPIC STRAIN POTENTIALS IN NONLINEAR POROUS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    刘熠; 黄筑平

    2003-01-01

    By taking a hollow sphere as a representative volume element (RVE), the macroscopic strain potentials of porous materials with power-law incompressible matrix are studied in this paper.According to the principles of the minimum potential energy in nonlinear elasticity and the variational procedure, static admissible stress fields and kinematic admissible displacement fields are constructed,and hence the upper and the lower bounds of the macroscopic strain potential are obtained. The bounds given in the present paper differ so slightly that they both provide perfect approximations of the exact strain potential of the studied porous materials. It is also found that the upper bound proposed by previous authors is much higher than the present one, and the lower bounds given by Cocks is much lower. Moreover, the present calculation is also compared with the variational lower bound of Ponte Castafneda for statistically isotropic porous materials. Finally, the validity of the hollow spherical RVE for the studied nonlinear porous material is discussed by the difference between the present numerical results and the Cocks bound.

  5. Macroscopic theory for capillary-pressure hysteresis.

    Science.gov (United States)

    Athukorallage, Bhagya; Aulisa, Eugenio; Iyer, Ram; Zhang, Larry

    2015-03-03

    In this article, we present a theory of macroscopic contact angle hysteresis by considering the minimization of the Helmholtz free energy of a solid-liquid-gas system over a convex set, subject to a constant volume constraint. The liquid and solid surfaces in contact are assumed to adhere weakly to each other, causing the interfacial energy to be set-valued. A simple calculus of variations argument for the minimization of the Helmholtz energy leads to the Young-Laplace equation for the drop surface in contact with the gas and a variational inequality that yields contact angle hysteresis for advancing/receding flow. We also show that the Young-Laplace equation with a Dirichlet boundary condition together with the variational inequality yields a basic hysteresis operator that describes the relationship between capillary pressure and volume. We validate the theory using results from the experiment for a sessile macroscopic drop. Although the capillary effect is a complex phenomenon even for a droplet as various points along the contact line might be pinned, the capillary pressure and volume of the drop are scalar variables that encapsulate the global quasistatic energy information for the entire droplet. Studying the capillary pressure versus volume relationship greatly simplifies the understanding and modeling of the phenomenon just as scalar magnetic hysteresis graphs greatly aided the modeling of devices with magnetic materials.

  6. Martensite transformation induced by deformation and its phase electrochemical behavior for stainless steels AISI 304 and 316L

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The martensite transformation induced by tensile elongation and its effect on the behavior of phase electrochemistry of AISI 304 and 316L in 3.5% NaCl solution were studied. The results show that the content of ((-martensite in stainless steel 304 increases with the true strain. As ((-martensite content increased, free corrosion potential and pitting potential of stainless steel 304 in 3.5% NaCl solution appeared the change trend of a minimum. It was also found that pitting nucleated preferentially at the phase interfaces between martensite and austenite. There existed apparent difference between electrochemical properties of austenite and of martensite for stainless steel 304 and 316L in 3.5% NaCl solution.

  7. Stress and temperature dependence of the avalanche dynamics during creep deformation of metallic glasses.

    Science.gov (United States)

    Herrero-Gómez, Carlos; Samwer, Konrad

    2016-09-22

    The understanding of the mesoscopic origin of plasticity in metallic glasses remains still an open issue. At the microscopic level, Shear Transformation Zones (STZ), composed by dozens of atoms, have been identified as the basic unit of the deformation process. Macroscopically, metallic glasses perform either homogeneous or inhomogeneous flow depending on the experimental conditions. However, the emergence of macroscopic behavior resulting from STZ interactions is still an open issue and is of great interest. In the current work we present an approach to analyze the different interaction mechanisms of STZ's by studying the statistics of the avalanches produced by a metallic glass during tensile creep deformation. We identified a crossover between different regimes of avalanches, and we analyzed the dependence of such crossover on the experimental conditions, namely stress and temperature. We interpret such crossover as a transition from 3D random STZ activity to localized 2D nano-shear bands. The experimental time at which the crossover takes place seems to depend on the overall strain and strain rate in the sample.

  8. A Study on Deformation Behavior of 304L Stainless Steel During and After Plate Rolling at Elevated Temperatures

    Science.gov (United States)

    Pourabdollah, P.; Serajzadeh, S.

    2017-02-01

    In this work, microstructural evolutions and mechanical properties of AISI 304L stainless steel were studied after rolling operations at elevated temperatures. Rolling experiments were conducted under warm and hot rolling conditions in the range of 600-1000 °C employing different reductions. Then, the developed microstructures and the mechanical properties of the steel were evaluated by means of uniaxial tensile testing, metallographic observations, and x-ray diffraction method. Besides, two-dimensional finite element analysis coupled with artificial neural network modeling was developed to assess thermo-mechanical behavior of the steel during and after rolling. The results show that inhomogeneities in strain and temperature distributions are reduced under warm rolling conditions. Static recrystallization can be operative under hot rolling conditions and relatively low reduction, i.e., reduction of 25%. However, for the case of higher reductions, the rate of recrystallization decreases considerably owing to severe temperature drop in the plate being rolled. Furthermore, the rolled plates show negative strain rate sensitivity while this phenomenon is affected by the rolling temperature.

  9. Deformation Behavior of Al0.25CoCrFeNi High-Entropy Alloy after Recrystallization

    Directory of Open Access Journals (Sweden)

    Jinxiong Hou

    2017-03-01

    Full Text Available Cold rolling with subsequent annealing can be used to produce the recrystallized structure in high entropy alloys (HEAs. The Al0.25CoCrFeNi HEAs rolled to different final thickness (230, 400, 540, 800, 1000, 1500 μm are prepared to investigate their microstructure evolutions and mechanical behaviors after annealing. Only the single face-centered cubic phase was obtained after cold rolling and recrystallization annealing at 1100 °C for 10 h. The average recrystallized grain size in this alloy after annealing ranges from 92 μm to 136 μm. The annealed thin sheets show obviously size effects on the flow stress and formability. The yield strength and tensile strength decrease as t/d (thickness/average grain diameter ratio decreases until the t/d approaches 2.23. In addition, the stretchability (formability decreases with the decrease of the t/d ratio especially when the t/d ratio is lower than about 6. According to the present results, yield strength can be expressed as a function of the t/d ratio.

  10. Deformation behavior of laser welds in high temperature oxidation resistant Fe-Cr-Al alloys for fuel cladding applications

    Science.gov (United States)

    Field, Kevin G.; Gussev, Maxim N.; Yamamoto, Yukinori; Snead, Lance L.

    2014-11-01

    Ferritic-structured Fe-Cr-Al alloys are being developed and show promise as oxidation resistant accident tolerant light water reactor fuel cladding. This study focuses on investigating the weldability and post-weld mechanical behavior of three model alloys in a range of Fe-(13-17.5)Cr-(3-4.4)Al (wt.%) with a minor addition of yttrium using modern laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds using sub-sized, flat dog-bone tensile specimens and digital image correlation (DIC) has been carried out to determine the performance of welds as a function of alloy composition. Results indicated a reduction in the yield strength within the fusion zone compared to the base metal. Yield strength reduction was found to be primarily constrained to the fusion zone due to grain coarsening with a less severe reduction in the heat affected zone. For all proposed alloys, laser welding resulted in a defect free weld devoid of cracking or inclusions.

  11. Deformation microstructures

    DEFF Research Database (Denmark)

    Hansen, N.; Huang, X.; Hughes, D.A.

    2004-01-01

    Microstructural characterization and modeling has shown that a variety of metals deformed by different thermomechanical processes follows a general path of grain subdivision, by dislocation boundaries and high angle boundaries. This subdivision has been observed to very small structural scales...... of the order of 10 nm, produced by deformation under large sliding loads. Limits to the evolution of microstructural parameters during monotonic loading have been investigated based on a characterization by transmission electron microscopy. Such limits have been observed at an equivalent strain of about 10...

  12. Inhomogeneous deformation in INCONEL 718 during monotonic and cyclic loadings

    Science.gov (United States)

    Worthem, D. W.; Robertson, I. M.; Socie, D. F.; Altstetter, C. J.; Leckie, F. A.

    1990-01-01

    The paper concentrates on the relation between microstructural observations of the dislocation structures and the macroscopic deformation responses of both aged and homogenized precipitate-hardened alloys at room temperature. The deformation responses are compared to the cyclic deformation response of an aged precipitate-hardened alloy. Early in the deformation, one deformation band per grain and little evidence of work hardening are observed; with increased deformation, work hardening begins, more bands nucleate, and their spacing becomes similar to that in the aged material. It is pointed out that the degree of coarseness of inhomogeneous deformation is not a result of a softening process within the bands due to precipitate shearing, but it is a function of the amount of work hardening within the bands.

  13. Inelastic deformation in crystalline rocks

    Science.gov (United States)

    Rahmani, H.; Borja, R. I.

    2011-12-01

    The elasto-plastic behavior of crystalline rocks, such as evaporites, igneous rocks, or metamorphic rocks, is highly dependent on the behavior of their individual crystals. Previous studies indicate that crystal plasticity can be one of the dominant micro mechanisms in the plastic deformation of crystal aggregates. Deformation bands and pore collapse are examples of plastic deformation in crystalline rocks. In these cases twinning within the grains illustrate plastic deformation of crystal lattice. Crystal plasticity is governed by the plastic deformation along potential slip systems of crystals. Linear dependency of the crystal slip systems causes singularity in the system of equations solving for the plastic slip of each slip system. As a result, taking the micro-structure properties into account, while studying the overall behavior of crystalline materials, is quite challenging. To model the plastic deformation of single crystals we use the so called `ultimate algorithm' by Borja and Wren (1993) implemented in a 3D finite element framework to solve boundary value problems. The major advantage of this model is that it avoids the singularity problem by solving for the plastic slip explicitly in sub steps over which the stress strain relationship is linear. Comparing the results of the examples to available models such as Von Mises we show the significance of considering the micro-structure of crystals in modeling the overall elasto-plastic deformation of crystal aggregates.

  14. Effect of microstructure on the corrosion and deformation behavior of a newly developed 6Mn-5Cr-1.5Cu corrosion-resistant white iron

    Science.gov (United States)

    Rao, P. N. V. R. S. S. V. Prasada; Patwardhan, A. K.; Jain, N. C.

    1993-02-01

    An experimental study has been made of the effect of heat treatment on the transformation behavior of a 4.8 pct Cr white iron, alloyed with 6 pct Mn and 1.5 pct Cu, by employing optical metallography, X-ray diffractometry, and differential thermal analysis (DTA) techniques, with a view to assess the suitability of the different microstructures in resisting aqueous corrosion. The matrix microstructure in the as-cast condition, comprising pearlite + bainite/martensite, transformed to austenite on heat-treating at all the temperatures between 900 °C and 1050 °C. Increasing the soaking period at each of the heat-treating temperatures led to an increase in the volume fraction and stability of austenite. M3C was the dominant carbide present in the as-cast condition. On heat-treating, different carbides formed: M23C6 carbide was present on heat-treating at 900 °C and 950 °C; on heat-treating at 1000 °C, M7C3 formed and persisted even on heattreating at 1050 °C. The possible formation of M5C2 carbide in the as-cast and heat-treated conditions (900 °C and 950 °C) is also indicated. Dispersed carbides (DC), present in austenite up to 950 °C, mostly comprised M3C and M5C2. On stress relieving of the heat-treated samples, M7C3-type DC also formed. The hardness changes were found to be consistent with the micro-structural changes occurring on heat-treating. The as-cast state was characterized by a reasonable resistance to corrosion in 5 pct NaCl solution. On heat-treating, the corrosion resistance improved over that in the as-cast state. After 4 hours soaking, increasing the temperature from 900 °C to 1050 °C led to an improvement in corrosion resistance. However, after 10 hours soaking, corrosion resistance decreased on increasing the temperature from 900 °C to 950 °C and improved thereafter on increasing the heat-treating temperature. Deformation behavior responded to the microstructure on similar lines as the corrosion behavior. Although in an early stage of

  15. Microscopic versus macroscopic calculation of dielectric nanospheres

    Science.gov (United States)

    Kühn, M.; Kliem, H.

    2008-12-01

    The issue of nanodielectrics has recently become an important field of interest. The term describes nanometric dielectrics, i. e. dielectric materials with structural dimensions typically smaller than 100 run. In contrast to the behaviour of a bulk material the nanodielectrics can behave completely different. With shrinking dimensions the surface or rather boundary effects outweigh the volume effects. This leads to a different observable physics at the nanoscale. A crucial point is the question whether a continuum model for the calculation of dielectric properties is still applicable for these nanomaterials. In order to answer this question we simulated dielectric nanospheres with a microscopic local field method and compared the results to the macroscopic mean field theory.

  16. Partitioning a macroscopic system into independent subsystems

    Science.gov (United States)

    Delle Site, Luigi; Ciccotti, Giovanni; Hartmann, Carsten

    2017-08-01

    We discuss the problem of partitioning a macroscopic system into a collection of independent subsystems. The partitioning of a system into replica-like subsystems is nowadays a subject of major interest in several fields of theoretical and applied physics. The thermodynamic approach currently favoured by practitioners is based on a phenomenological definition of an interface energy associated with the partition, due to a lack of easily computable expressions for a microscopic (i.e. particle-based) interface energy. In this article, we outline a general approach to derive sharp and computable bounds for the interface free energy in terms of microscopic statistical quantities. We discuss potential applications in nanothermodynamics and outline possible future directions.

  17. Casimir effect from macroscopic quantum electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Philbin, T G, E-mail: tgp3@st-andrews.ac.uk [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS (United Kingdom)

    2011-06-15

    The canonical quantization of macroscopic electromagnetism was recently presented in (Philbin 2010 New J. Phys. 12 123008). This theory is used here to derive the Casimir effect, by considering the special case of thermal and zero-point fields. The stress-energy-momentum tensor of the canonical theory follows from Noether's theorem, and its electromagnetic part in thermal equilibrium gives the Casimir energy density and stress tensor. The results hold for arbitrary inhomogeneous magnetodielectrics and are obtained from a rigorous quantization of electromagnetism in dispersive, dissipative media. Continuing doubts about the status of the standard Lifshitz theory as a proper quantum treatment of Casimir forces do not apply to the derivation given here. Moreover, the correct expressions for the Casimir energy density and stress tensor inside media follow automatically from the simple restriction to thermal equilibrium, without the need for complicated thermodynamical or mechanical arguments.

  18. Taming macroscopic jamming in transportation networks

    CERN Document Server

    Ezaki, Takahiro; Nishinari, Katsuhiro

    2015-01-01

    In transportation networks, a spontaneous jamming transition is often observed, e.g in urban road networks and airport networks. Because of this instability, flow distribution is significantly imbalanced on a macroscopic level. To mitigate the congestion, we consider a simple control method, in which congested nodes are closed temporarily, and investigate how it influences the overall system. Depending on the timing of the node closure and opening, and congestion level of a network, the system displays three different phases: free-flow phase, controlled phase, and deadlock phase. We show that when the system is in the controlled phase, the average flow is significantly improved, whereas when in the deadlock phase, the flow drops to zero. We study how the control method increases the network flow and obtain their transition boundary analytically.

  19. Black Holes and Quantumness on Macroscopic Scales

    CERN Document Server

    Flassig, D; Wintergerst, N

    2012-01-01

    It has recently been suggested that black holes may be described as condensates of weakly interacting gravitons at a critical point, exhibiting strong quantum effects. In this paper, we study a model system of attractive bosons in one spatial dimension which is known to undergo a quantum phase transition. We demonstrate explicitly that indeed quantum effects are important at the critical point, even if the number of particles is macroscopic. Most prominently, we evaluate the entropy of entanglement between different momentum modes and observe it to become maximal at the critical point. Furthermore, we explicitly see that the leading entanglement is between long wavelength modes and is hence a feature independent of ultraviolet physics. If applicable to black holes, our findings substantiate the conjectured breakdown of semiclassical physics even for large black holes. This can resolve long standing mysteries, such as the information paradox and the no-hair theorem.

  20. Variability of macroscopic dimensions of Moso bamboo.

    Science.gov (United States)

    Cui, Le; Peng, Wanxi; Sun, Zhengjun; Sun, Zhengjun; Sun, Zhengjun; Lu, Huangfei; Chen, Guoning

    2015-03-01

    In order to the macroscopic geometry distributions of vascular bundles in Moso bamboo tubes. The circumference of bamboo tubes was measured, used a simple quadratic diameter formula to analyze the differences between the tubes in bamboo culm, and the arrangement of vascular bundles was investigated by cross sectional images of bamboo tubes. The results shown that the vascular bundles were differently distributed in a bamboo tube. In the outer layer, the vascular bundles had a variety of shapes, and were aligned parallel to each other. In the inner layers, the vascular bundles weren't aligned but uniform in shape. It was concluded that the vascular bundle sections arranged in parallel should be separated from the non-parallel sections for the maximum bamboo utilization.