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Chao Yu - One of the best experts on this subject based on the ideXlab platform.
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effect of martensite reorientation and reorientation induced plasticity on multiaxial transformation ratchetting of super elastic niti shape memory alloy new consideration in constitutive model
International Journal of Plasticity, 2015Co-Authors: Chao Yu, Guozheng Kang, Di SongAbstract:Abstract Experimental results show that the martensite reorientation and reorientation-induced plasticity play critical roles on the non-proportional multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy (SMA) (Song et al., 2014b). In this paper, the multiaxial transformation ratchetting of the NiTi shape memory alloy is described by developing a new constitutive model in the framework of crystal plasticity. Besides the well-known inelastic mechanisms of NiTi shape memory alloys, such as the martensite transformation, martensite reorientation, transformation-induced plasticity and accumulated residual martensite, a new inelastic deformation mechanism, i.e., reorientation-induced plasticity is included in the proposed model to address its effect on multiaxial transformation ratchetting. The constitutive model is constructed in the single crystal scale and extended to a polycrystalline version by adopting an explicit scale-Transition Rule. By comparing the predicted results with the corresponding experimental ones, it is verified that the proposed model describes the non-proportional multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy more reasonably by considering the martensite reorientation and reorientation-induced plasticity simultaneously.
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crystal plasticity based constitutive model of niti shape memory alloy considering different mechanisms of inelastic deformation
International Journal of Plasticity, 2014Co-Authors: Chao Yu, Guozheng KangAbstract:Abstract To comprehensively describe the deformation behaviors of polycrystalline NiTi shape memory alloy under various thermo-mechanical loading conditions, a micromechanical constitutive model is constructed based on crystal plasticity. At the scale of single crystal, 24 martensite variants are introduced. Different mechanisms of inelastic deformation in the NiTi shape memory alloy, including martensite transformation, martensite reorientation and detwinning, dislocation slipping in the austenite and twinning in the martensite, are considered in the proposed model. The Helmholtz free energy for the representative volume element of a single crystal is constructed and the thermodynamic driving forces of internal variables are obtained from the dissipative inequalities. The evolution equations of internal variables are deduced in power-law forms. The differences of elastic properties between the austenite and martensite phases, as well as the restraint effect of twinning in the martensite on the reverse transformation, are considered. A simplified explicit scale-Transition Rule is adopted to extend the single crystal model to a polycrystalline version. Finally, the capability of proposed model to describe the various thermo-mechanical deformation behaviors of polycrystalline NiTi alloy is verified by comparing the simulated results with the experimental ones.
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a micromechanical constitutive model based on crystal plasticity for thermo mechanical cyclic deformation of niti shape memory alloys
International Journal of Plasticity, 2013Co-Authors: Chao Yu, Guozheng Kang, Di SongAbstract:Abstract Based on crystal plasticity, a new micromechanical constitutive model is constructed to describe the cyclic deformation of polycrystalline NiTi shape memory alloy presented under different thermo-mechanical cyclic loading conditions. At the scale of single crystal, the phase transformation and transformation-induced plasticity of the NiTi shape memory alloys are considered to be related with the 24 martensite variants and the friction systems at austenite–martensite interfaces, respectively. Three kinds of internal variables are included in the single crystal model, i.e., the reversible martensite volume fraction, the residual martensite volume fraction, and the friction slip at austenite–martensite interfaces. The Helmholtz free energy for the representative volume element of NiTi single crystal is constructed and the thermodynamics driving forces for internal variables are obtained by corresponding dissipation inequalities, respectively. An explicit scale-Transition Rule is adopted to extend the proposed single crystal model to the polycrystalline version. Also, the initial crystallographic texture is addressed in order to reflect the anisotropic phase transformation behavior of the NiTi shape memory alloys presented in the tension and compression cases. The proposed model is firstly verified by comparing the simulations with the corresponding uniaxial cyclic deformation experiments of polycrystalline NiTi shape memory alloys, and then is discussed by describing the multiaxial cyclic deformation of the polycrystalline NiTi shape memory alloy under the strain-controlled and stress-controlled cyclic loading conditions with different multiaxial loading paths and predicting the recovery of residual martensite phase during the sequential heating. Finally, some details about the cyclic deformation of polycrystalline NiTi shape memory alloy in intra-granular scale are also addressed with the help of the proposed model.
Guozheng Kang - One of the best experts on this subject based on the ideXlab platform.
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effect of martensite reorientation and reorientation induced plasticity on multiaxial transformation ratchetting of super elastic niti shape memory alloy new consideration in constitutive model
International Journal of Plasticity, 2015Co-Authors: Chao Yu, Guozheng Kang, Di SongAbstract:Abstract Experimental results show that the martensite reorientation and reorientation-induced plasticity play critical roles on the non-proportional multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy (SMA) (Song et al., 2014b). In this paper, the multiaxial transformation ratchetting of the NiTi shape memory alloy is described by developing a new constitutive model in the framework of crystal plasticity. Besides the well-known inelastic mechanisms of NiTi shape memory alloys, such as the martensite transformation, martensite reorientation, transformation-induced plasticity and accumulated residual martensite, a new inelastic deformation mechanism, i.e., reorientation-induced plasticity is included in the proposed model to address its effect on multiaxial transformation ratchetting. The constitutive model is constructed in the single crystal scale and extended to a polycrystalline version by adopting an explicit scale-Transition Rule. By comparing the predicted results with the corresponding experimental ones, it is verified that the proposed model describes the non-proportional multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy more reasonably by considering the martensite reorientation and reorientation-induced plasticity simultaneously.
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crystal plasticity based constitutive model of niti shape memory alloy considering different mechanisms of inelastic deformation
International Journal of Plasticity, 2014Co-Authors: Chao Yu, Guozheng KangAbstract:Abstract To comprehensively describe the deformation behaviors of polycrystalline NiTi shape memory alloy under various thermo-mechanical loading conditions, a micromechanical constitutive model is constructed based on crystal plasticity. At the scale of single crystal, 24 martensite variants are introduced. Different mechanisms of inelastic deformation in the NiTi shape memory alloy, including martensite transformation, martensite reorientation and detwinning, dislocation slipping in the austenite and twinning in the martensite, are considered in the proposed model. The Helmholtz free energy for the representative volume element of a single crystal is constructed and the thermodynamic driving forces of internal variables are obtained from the dissipative inequalities. The evolution equations of internal variables are deduced in power-law forms. The differences of elastic properties between the austenite and martensite phases, as well as the restraint effect of twinning in the martensite on the reverse transformation, are considered. A simplified explicit scale-Transition Rule is adopted to extend the single crystal model to a polycrystalline version. Finally, the capability of proposed model to describe the various thermo-mechanical deformation behaviors of polycrystalline NiTi alloy is verified by comparing the simulated results with the experimental ones.
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a micromechanical constitutive model based on crystal plasticity for thermo mechanical cyclic deformation of niti shape memory alloys
International Journal of Plasticity, 2013Co-Authors: Chao Yu, Guozheng Kang, Di SongAbstract:Abstract Based on crystal plasticity, a new micromechanical constitutive model is constructed to describe the cyclic deformation of polycrystalline NiTi shape memory alloy presented under different thermo-mechanical cyclic loading conditions. At the scale of single crystal, the phase transformation and transformation-induced plasticity of the NiTi shape memory alloys are considered to be related with the 24 martensite variants and the friction systems at austenite–martensite interfaces, respectively. Three kinds of internal variables are included in the single crystal model, i.e., the reversible martensite volume fraction, the residual martensite volume fraction, and the friction slip at austenite–martensite interfaces. The Helmholtz free energy for the representative volume element of NiTi single crystal is constructed and the thermodynamics driving forces for internal variables are obtained by corresponding dissipation inequalities, respectively. An explicit scale-Transition Rule is adopted to extend the proposed single crystal model to the polycrystalline version. Also, the initial crystallographic texture is addressed in order to reflect the anisotropic phase transformation behavior of the NiTi shape memory alloys presented in the tension and compression cases. The proposed model is firstly verified by comparing the simulations with the corresponding uniaxial cyclic deformation experiments of polycrystalline NiTi shape memory alloys, and then is discussed by describing the multiaxial cyclic deformation of the polycrystalline NiTi shape memory alloy under the strain-controlled and stress-controlled cyclic loading conditions with different multiaxial loading paths and predicting the recovery of residual martensite phase during the sequential heating. Finally, some details about the cyclic deformation of polycrystalline NiTi shape memory alloy in intra-granular scale are also addressed with the help of the proposed model.
Di Song - One of the best experts on this subject based on the ideXlab platform.
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effect of martensite reorientation and reorientation induced plasticity on multiaxial transformation ratchetting of super elastic niti shape memory alloy new consideration in constitutive model
International Journal of Plasticity, 2015Co-Authors: Chao Yu, Guozheng Kang, Di SongAbstract:Abstract Experimental results show that the martensite reorientation and reorientation-induced plasticity play critical roles on the non-proportional multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy (SMA) (Song et al., 2014b). In this paper, the multiaxial transformation ratchetting of the NiTi shape memory alloy is described by developing a new constitutive model in the framework of crystal plasticity. Besides the well-known inelastic mechanisms of NiTi shape memory alloys, such as the martensite transformation, martensite reorientation, transformation-induced plasticity and accumulated residual martensite, a new inelastic deformation mechanism, i.e., reorientation-induced plasticity is included in the proposed model to address its effect on multiaxial transformation ratchetting. The constitutive model is constructed in the single crystal scale and extended to a polycrystalline version by adopting an explicit scale-Transition Rule. By comparing the predicted results with the corresponding experimental ones, it is verified that the proposed model describes the non-proportional multiaxial transformation ratchetting of super-elastic NiTi shape memory alloy more reasonably by considering the martensite reorientation and reorientation-induced plasticity simultaneously.
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a micromechanical constitutive model based on crystal plasticity for thermo mechanical cyclic deformation of niti shape memory alloys
International Journal of Plasticity, 2013Co-Authors: Chao Yu, Guozheng Kang, Di SongAbstract:Abstract Based on crystal plasticity, a new micromechanical constitutive model is constructed to describe the cyclic deformation of polycrystalline NiTi shape memory alloy presented under different thermo-mechanical cyclic loading conditions. At the scale of single crystal, the phase transformation and transformation-induced plasticity of the NiTi shape memory alloys are considered to be related with the 24 martensite variants and the friction systems at austenite–martensite interfaces, respectively. Three kinds of internal variables are included in the single crystal model, i.e., the reversible martensite volume fraction, the residual martensite volume fraction, and the friction slip at austenite–martensite interfaces. The Helmholtz free energy for the representative volume element of NiTi single crystal is constructed and the thermodynamics driving forces for internal variables are obtained by corresponding dissipation inequalities, respectively. An explicit scale-Transition Rule is adopted to extend the proposed single crystal model to the polycrystalline version. Also, the initial crystallographic texture is addressed in order to reflect the anisotropic phase transformation behavior of the NiTi shape memory alloys presented in the tension and compression cases. The proposed model is firstly verified by comparing the simulations with the corresponding uniaxial cyclic deformation experiments of polycrystalline NiTi shape memory alloys, and then is discussed by describing the multiaxial cyclic deformation of the polycrystalline NiTi shape memory alloy under the strain-controlled and stress-controlled cyclic loading conditions with different multiaxial loading paths and predicting the recovery of residual martensite phase during the sequential heating. Finally, some details about the cyclic deformation of polycrystalline NiTi shape memory alloy in intra-granular scale are also addressed with the help of the proposed model.
J O Haenni - One of the best experts on this subject based on the ideXlab platform.
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von neumann s 29 state cellular automaton a hardware implementation
IEEE Transactions on Education, 2000Co-Authors: Jeanluc Beuchat, J O HaenniAbstract:In the early 1950s, John von Neumann designed a cellular automaton implementing a universal self-replicating structure. More than 40 years after his death, the first hardware implementation of von Neumann's Transition Rule is presented. Unfortunately, this implementation only allows small systems to be realized, and not the complete structure, which would require 100000-200000 cells, according to some estimations. A logic circuit which implements the Transition Rule and represents a single cell of the array has been developed. The applications of this implementation lie mainly in the pedagogical domain. It can be used as a demonstration tool for courses on cellular automata.
Georges Cailletaud - One of the best experts on this subject based on the ideXlab platform.
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a polycrystalline model for the description of ratchetting effect of intergranular and intragranular hardening
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Georges CailletaudAbstract:In this work, numerical simulations for predicting uni- and multi-axial ratchetting behaviors are carried out, using a polycrystal plasticity model. In this multi-scale modeling, the single crystal behavior is based on crystallographic slip (intragranular scale), whereas the polycrystal behavior is obtained from an explicit Transition Rule to calculate the local stresses and strains (intergranular scale). A systematic study is performed to show the effect of intergranular and intragranular hardening on the ratchetting behavior. For illustrative purposes, two examples are presented: the model is applied to simulate the experimental results from the literature for a 316 austenitic stainless steel and for a 1026 carbon steel. It was demonstrated that the polycrystalline model was successful in describing the inelastic behavior of the two considered materials adequately.
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multi mechanism models for the description of ratchetting effect of the scale Transition Rule and of the coupling between hardening variables
International Journal of Plasticity, 2007Co-Authors: Kacem Sai, Georges CailletaudAbstract:Abstract This paper is concerned with two multi-mechanism based models for application to ratchetting effect. The 2M1C (2 Mechanisms and 1 Criterion) model and 2M2C (2 Mechanisms and Criteria) model, proposed by the authors in a previous article, are modified to incorporate (i) a corrective term in the computation of the local stresses; (ii) Burlet–Cailletaud’s fading memory term in the kinematic hardening evolution Rule. Experimental data from the literature are selected to assess the models capability. Numerical results are obtained using the proposed models for a series of uni-axial and multi-axial ratchetting tests performed at different stress ranges of an austenitic stainless steel.
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Computational crystal plastiticy : from single crystal to homogenized polycrystals
Technische Mechanik, 2003Co-Authors: Georges Cailletaud, Olivier Diard, Frédéric Feyel, Samuel ForestAbstract:Crystal plasticity models for single crystals at large deformation are shown. An extension to the computation of polycrystals is also proposed. The scale Transition Rule is numerically identified on polycrystal computations, and is valid for any type of loading. All these models are implemented in a finite element code, which has a sequential and a parallel version. Parallel processing makes CPU time reasonable, even for 3D meshes involving a large number of internal variables (more than 1000) at each Gauss point. Together with a presentation of the numerical tools, the paper shows several applications, a study of the crack tip strain fields in single crystals, of zinc coating on a steel substrate, specimen computation involving a large number of grains in each Gauss point. Finally, polycrystalline aggregates are generated, and numerically tested. The effect of grain boundary damage, opening and sliding is investigated.
