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Xu Chen - One of the best experts on this subject based on the ideXlab platform.
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RATCHETING OF STAINLESS STEEL 304 UNDER MULTIAXIAL NONPROPORTIONAL LOADING
2020Co-Authors: Kwang S Kim, Rong Jiao, Xu Chen, Masao SakaneAbstract:ABSTRACT Ratcheting tests are conducted on stainless steel 304 under uniaxial, torsional, and combined axial-torsional loading. The ratcheting strain is predicted based on the constitutive theory that incorporates a modified Ohno-Wang Kinematic Hardening Rule and Tanaka's isotropic Hardening model. The results show that the main features of the stress-strain response can be simulated with the constitutive model. The experimental and predicted ratcheting strains for nonproportional paths are found in decent correlation. Ratcheting strain depends highly on the loading path and load level, and less on cyclic Hardening or softening of the material. The torsional ratcheting strain under mean shear stress with (or without) fully reversed axial strain cycling is found close to the axial ratcheting strain under equivalent mean stress with (or without) torsional strain cycling
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cyclic deformation of 316l stainless steel and constitutive modeling under non proportional variable loading path
International Journal of Plasticity, 2019Co-Authors: Ruisi Xing, Shouwen Shi, Xu ChenAbstract:Abstract In order to investigate the effect of non-proportional loading history on cyclic deformation of 316L stainless steel, a series of multiaxial cyclic experiments with variable loading path are conducted at room temperature. It is found that the materials exhibit cyclic Hardening at initial stage, followed by a long period of cyclic softening. Significant cyclic softening is observed when non-proportional loading path changes into proportional loading path and the rate of cyclic softening is related to non-proportional loading history. A visco-plasticity constitutive model based on Ohno-Wang Kinematic Hardening Rule and Marquis isotropic Hardening Rule is used to characterize non-proportional cyclic behavior. Simulation results agree with experiments very well in terms of cyclic Hardening effects. However, this model is found to be less effective in simulating cyclic softening effect, especially considering the influence of non-proportional loading history. A modified isotropic Hardening model is thus proposed to simulate the cyclic softening behavior of 316L stainless steel by introducing a memory non-proportionality and qualifying a partial recoverable softening term of isotropic Hardening Rule. Simulation results of the proposed model agree much better with experimental values.
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applying viscoplastic constitutive models to predict ratcheting behavior of sintered nanosilver lap shear joint
Mechanics of Materials, 2014Co-Authors: Gang Chen, Yunhui Mei, Zesheng Zhang, Lei Wang, Xu ChenAbstract:Abstract A series of displacement-controlled tests were conducted for sintered nanosilver lap-shear joints at different loading rates and temperatures. The relationship between force and displacement was studied. It was found that higher loading rate or lower temperature caused higher stress–strain response of the sintered nanosilver joint. Force-controlled cyclic tests were also performed at different mean forces, force amplitudes, dwell time at peak force, and temperatures. The mean force, the force amplitude, and the temperature played key roles in the shear ratcheting strain accumulation. The ratcheting strain rate could be enhanced with increasing the dwell time at peak force as well. A viscoplastic constitutive model based on Ohno–Wang and Armstrong–Fedrick (OW–AF) non-linear Kinematic Hardening Rule, and Anand model were separately embedded in ABAQUS to simulate the shear and the ratcheting behavior of the sintered nanosilver joint. It was concluded that OW–AF model could predict the ratcheting behavior of the sintered nanosilver joint better than Anand model, especially at high temperatures.
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thermo viscoplastic modeling incorporating dynamic strain aging effect on the uniaxial behavior of z2cnd18 12n stainless steel
International Journal of Plasticity, 2012Co-Authors: Xu Chen, Gang ChenAbstract:Abstract Monotonic tension, isothermal/anisothermal fully reversed strain cycling and zero-to-tension cyclic tests were conducted within the temperature domain from room temperature to 823 K to investigate the mechanical behavior of Z2CND18.12N austenitic stainless steel under various uniaxial loading conditions. Interesting results were observed from these tests, including obvious rate-dependence at room temperature but lack of rate-dependence at elevated temperatures with the occurrence of serrated flow stress in tensile tests, more cyclic Hardening at higher temperature in strain cycling tests, and tendency to reach shakedown condition at elevated temperatures in zero-to-tension cyclic tests. Dynamic strain aging (DSA) effect was presumably believed to contribute to these characteristics of the material. A thermo-viscoplastic constitutive model was proposed to describe the mechanical behavior of the material under uniaxial loading conditions at small strains. Kinematic Hardening Rule with two components of back stress and isotropic Hardening Rule incorporating DSA effect are the novel features of the proposed model. The simulated and predicted results show reasonable agreement with the experimental data.
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visco plastic constitutive modeling on ohno wang Kinematic Hardening Rule for uniaxial ratcheting behavior of z2cnd18 12n steel
International Journal of Plasticity, 2012Co-Authors: Gang Chen, Xu ChenAbstract:Abstract Experimental results of monotonic uniaxial tensile tests at different strain rates and the reversed strain cycling test showed the characteristics of rate-dependence and cyclic Hardening of Z2CND18.12N austenitic stainless steel at room temperature, respectively. Based on the Ohno–Wang Kinematic Hardening Rule, a visco-plastic constitutive model incorporated with isotropic Hardening was developed to describe the uniaxial ratcheting behavior of Z2CND18.12N steel under various stress-controlled loading conditions. Predicted results of the developed model agreed better with experimental results when the ratcheting strain level became higher, but the developed model overestimated the ratcheting deformation in other cases. A modified model was proposed to improve the prediction accuracy. In the modified model, the parameter m i of the Ohno–Wang Kinematic Hardening Rule was developed to evolve with the accumulated plastic strain. Simulation results of the modified model proved much better agreement with experiments.
Guozheng Kang - One of the best experts on this subject based on the ideXlab platform.
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a finite cyclic elasto plastic constitutive model to improve the description of cyclic stress strain hysteresis loops
International Journal of Plasticity, 2017Co-Authors: Yilin Zhu, Guozheng KangAbstract:Abstract Plenty of cyclic constitutive models have been developed to describe the cyclic Hardening/softening feature and ratchetting behavior of metals and good descriptions can be obtained. The cyclic stress-strain hysteresis loops, however, cannot be well predicted by most of the existing models since the different plastic moduli between monotonic and cyclic deformations have rarely been considered. In this work, a finite cyclic elasto-plastic constitutive model is developed to improve the description of the cyclic stress-strain hysteresis loops by introducing a new proposed Kinematic Hardening Rule and an exponential isotropic Hardening Rule. In the proposed Kinematic Hardening Rule, the back stress is decomposed into long-range, middle-range and short-range components with each addressing an “Armstrong-Frederick” evolution Rule consisting of a linear Hardening and a dynamic recovery term (Armstrong and Frederick, 1966). For the long-range and middle-range components, the dynamic recovery coefficients are postulated to decrease with the increase of plastic deformation and each contains a ratchetting coefficient. For the short-range component, the linear Hardening and dynamic recovery terms are further divided into two parts, respectively, with one part in each activating only when the reverse loading occurs. The capability of the proposed model is demonstrated by benchmarking its predictions against experimental data. It is shown that the monotonic stress-strain response, cyclic Hardening with both small and large strain amplitudes, ratchetting and, particularly, the cyclic stress-strain hysteresis loops of metallic materials can be well described by the proposed model.
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viscoelastic viscoplastic cyclic deformation of polycarbonate polymer experiment and constitutive model
Journal of Applied Mechanics, 2016Co-Authors: Guozheng Kang, Yilin Zhu, Kaijuan ChenAbstract:A series of uniaxial tests (including multilevel loading–unloading recovery, creep-recovery, and cyclic tension–compression/tension ones) were performed to investigate the monotonic and cyclic viscoelastic–viscoplastic deformations of polycarbonate (PC) polymer at room temperature. The results show that the PC exhibits strong nonlinearity and rate-dependence, and obvious ratchetting occurs during the stress-controlled cyclic tension–compression/tension tests with nonzero mean stress, which comes from both the viscoelasticity and viscoplasticity of the PC. Based on the experimental observation, a nonlinear viscoelastic–viscoplastic cyclic constitutive model is then constructed. The viscoelastic part of the proposed model is constructed by extending the Schapery's nonlinear viscoelastic model, and the viscoplastic one is established by adopting the Ohno–Abdel-Karim's nonlinear Kinematic Hardening Rule to describe the accumulation of irrecoverable viscoplastic strain produced during cyclic loading. Furthermore, the dependence of elastic compliance of the PC on the accumulated viscoplastic strain is considered. Finally, the capability of the proposed model is verified by comparing the predicted results with the corresponding experimental ones of the PC. It is shown that the proposed model provides reasonable predictions to the various deformation characteristics of the PC presented in the multilevel loading–unloading recovery, creep-recovery, and cyclic tension–compression/tension tests.
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a new Kinematic Hardening Rule describing different plastic moduli in monotonic and cyclic deformations
2015Co-Authors: Yilin Zhu, Guozheng Kang, Qianhua KanAbstract:To describe the different plastic moduli of the metal materials presented in the monotonic and cyclic deformations, a new nonlinear Kinematic Hardening Rule is proposed by modifying the Chaboche’s one (Chaboche 1989). In the proposed Rule, the back stress is assumed to be decomposed into three components as done by Chaboche (1989), but the linear Hardening and dynamic recovery terms of each back stress component are further divided into two parts, respectively, and a part in each of them is only activated when the reverse loading occurs so that the cyclic stress-strain hysteresis loops can be predicted more accurately; moreover, a rachetting coefficient is introduced into one part of dynamic recovery term to describe the ratchetting. The proposed Rule can be reduced to the Chaboche’s one under the monotonic loading conditions, or by setting some material parameters as zero. Finally, the proposed model is verified by comparing the predicted results with corresponding experimental ones. It is seen that the predicted results are in good agreement with the corresponding experimental ones.
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a dislocation based cyclic polycrystalline visco plastic constitutive model for ratchetting of metals with face centered cubic crystal structure
Computational Materials Science, 2014Co-Authors: Yawei Dong, Guozheng KangAbstract:Abstract In the framework of crystal plasticity, a dislocation-based cyclic polycrystalline visco-plastic constitutive model is proposed to describe the ratchetting of the metals with a face-centered cubic (FCC) crystal structure. A new rate-dependent flow Rule considering the thermal activation energy of dislocation slipping is developed, and a dislocation-based Armstrong-Frederick non-linear Kinematic Hardening Rule is introduced to provide a better prediction to the ratchetting. The isotropic Hardening associated with the short-ranged interactions of dislocations is represented by the evolution of critical shear stress in each slip system. Comparing the prediction with corresponding experimental results, it is shown that the uniaxial and multiaxial ratchetting of polycrystalline 316L stainless steel are reasonably described by the proposed model. The dependence of the intra-granular ratchetting on the crystallographic orientation of grains can be also reflected by the model.
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logarithmic stress rate based constitutive model for cyclic loading in finite plasticity
International Journal of Plasticity, 2014Co-Authors: Yilin Zhu, Guozheng Kang, Qianhua Kan, Otto T BruhnsAbstract:Abstract Based on the logarithmic stress rate, a constitutive model is developed to describe the material behaviour under cyclic loading histories (including ratchetting) in the framework of finite plasticity by using combined nonlinear isotropic and Kinematic Hardening Rules. The nonlinear Kinematic Hardening Rule is extended from that developed by Abdel-Karim and Ohno (2000) for infinitesimal plasticity. The cyclic Hardening/softening feature of materials is reflected by using a nonlinear isotropic Hardening Rule. Then, the proposed model is implemented into a finite element code (e.g., ABAQUS) by employing a simple fully-implicit time-integration procedure. Finally, some numerical examples are carried out to verify the capability of the model to predict the cyclic deformation of materials in finite deformation by comparing the predictions with the corresponding experiment results in referable literature. The predicted stress responses during a simple shear with large shear strain and ratchetting during the cyclic loading tests in finite deformation are in good agreement with the corresponding experimental results.
A R Khoei - One of the best experts on this subject based on the ideXlab platform.
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a three invariant cap model with isotropic Kinematic Hardening Rule and associated plasticity for granular materials
International Journal of Solids and Structures, 2008Co-Authors: H Dormohammadi, A R KhoeiAbstract:Abstract In this paper, a three-invariant cap model is developed for the isotropic–Kinematic Hardening and associated plasticity of granular materials. The model is based on the concepts of elasticity and plasticity theories together with an associated flow Rule and a work Hardening law for plastic deformations of granulars. The Hardening Rule is defined by its decomposition into the isotropic and Kinematic material functions. The constitutive elasto-plastic matrix and its components are derived by using the definition of yield surface, material functions and non-linear elastic behavior, as function of Hardening parameters. The model assessment and procedure for determination of material parameters are described. Finally, the applicability of proposed plasticity model is demonstrated in numerical simulation of several triaxial and confining pressure tests on different granular materials, including: wheat, rape, synthetic granulate and sand.
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a three invariant cap plasticity with isotropic Kinematic Hardening Rule for powder materials model assessment and parameter calibration
Computational Materials Science, 2007Co-Authors: A R Khoei, H DormohammadiAbstract:Abstract The constitutive modeling of powder is clearly a keystone of successful quantitative solution possibilities. Without a reasonable constitutive model, which can reproduce complicated powder behavior under loading conditions, the computations are worthless. In this paper, a three-invariant cap plasticity model with isotropic–Kinematic Hardening Rule is presented for powder materials. A generalized single-cap plasticity is developed which can be compared with some common double-surface plasticity models proposed for powders in literature. The Hardening Rule is defined based on the isotropic and Kinematic material functions. The constitutive elasto-plastic matrix and its components are derived by using the definition of yield surface, material functions and nonlinear elastic behavior, as function of Hardening parameters. The procedure for determination of material parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.
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a three invariant cap plasticity model with Kinematic Hardening Rule for powder materials
Journal of Materials Processing Technology, 2007Co-Authors: A R Khoei, H Dormohammadi, A R AzamiAbstract:Abstract In this paper, a three-invariant cap plasticity with a Kinematic Hardening Rule is presented for powder materials. A general form is developed for the cap plasticity which can be compared with some common double-surface plasticity models proposed for powders in literature. The constitutive elasto-plastic matrix and its components are derived based on the definition of yield surface, Hardening parameter and non-linear elastic behavior, as function of relative density of powder. The procedure for determination of powder parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.
H Dormohammadi - One of the best experts on this subject based on the ideXlab platform.
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a three invariant cap model with isotropic Kinematic Hardening Rule and associated plasticity for granular materials
International Journal of Solids and Structures, 2008Co-Authors: H Dormohammadi, A R KhoeiAbstract:Abstract In this paper, a three-invariant cap model is developed for the isotropic–Kinematic Hardening and associated plasticity of granular materials. The model is based on the concepts of elasticity and plasticity theories together with an associated flow Rule and a work Hardening law for plastic deformations of granulars. The Hardening Rule is defined by its decomposition into the isotropic and Kinematic material functions. The constitutive elasto-plastic matrix and its components are derived by using the definition of yield surface, material functions and non-linear elastic behavior, as function of Hardening parameters. The model assessment and procedure for determination of material parameters are described. Finally, the applicability of proposed plasticity model is demonstrated in numerical simulation of several triaxial and confining pressure tests on different granular materials, including: wheat, rape, synthetic granulate and sand.
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a three invariant cap plasticity with isotropic Kinematic Hardening Rule for powder materials model assessment and parameter calibration
Computational Materials Science, 2007Co-Authors: A R Khoei, H DormohammadiAbstract:Abstract The constitutive modeling of powder is clearly a keystone of successful quantitative solution possibilities. Without a reasonable constitutive model, which can reproduce complicated powder behavior under loading conditions, the computations are worthless. In this paper, a three-invariant cap plasticity model with isotropic–Kinematic Hardening Rule is presented for powder materials. A generalized single-cap plasticity is developed which can be compared with some common double-surface plasticity models proposed for powders in literature. The Hardening Rule is defined based on the isotropic and Kinematic material functions. The constitutive elasto-plastic matrix and its components are derived by using the definition of yield surface, material functions and nonlinear elastic behavior, as function of Hardening parameters. The procedure for determination of material parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.
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a three invariant cap plasticity model with Kinematic Hardening Rule for powder materials
Journal of Materials Processing Technology, 2007Co-Authors: A R Khoei, H Dormohammadi, A R AzamiAbstract:Abstract In this paper, a three-invariant cap plasticity with a Kinematic Hardening Rule is presented for powder materials. A general form is developed for the cap plasticity which can be compared with some common double-surface plasticity models proposed for powders in literature. The constitutive elasto-plastic matrix and its components are derived based on the definition of yield surface, Hardening parameter and non-linear elastic behavior, as function of relative density of powder. The procedure for determination of powder parameters is described. Finally, the applicability of the proposed model is demonstrated in numerical simulation of triaxial and confining pressure tests.
Tasnim Hassan - One of the best experts on this subject based on the ideXlab platform.
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unified viscoplasticity modeling for isothermal low cycle fatigue and fatigue creep stress strain responses of haynes 230
International Journal of Solids and Structures, 2016Co-Authors: Raasheduddin Ahmed, Paul R Barrett, Tasnim HassanAbstract:Abstract A robust cyclic viscoplasticity model is developed for simulating a broad set of isothermal, low-cycle fatigue and fatigue-creep responses of Haynes 230 (HA 230) under uniaxial loading. High temperature components experiencing thermo-mechanical fatigue failures can be designed considering their failure responses such that their fatigue life is predictable. Hence, design of high temperature components in aerospace, automobile, nuclear power, and chemical industries should be based on viscoplastic nonlinear analysis using a robust constitutive model. A unified viscoplasticity model based on the nonlinear Kinematic Hardening Rule of Chaboche with several added features for strain-range dependence, rate-dependence, static recovery, and mean stress evolution is developed and evaluated against a broad set of HA 230 responses. Robustness of the constitutive model is demonstrated against predicting fatigue and dwell period stress relaxation responses under uniaxial strain-controlled loading for a broad temperature range of 25–982 °C and strain rate range of 1.1×10 −2 to 2.6×10 −5 /s. Parameter determination of such an advanced model is discussed showing the importance of a well thought out experimental database and thereby providing physical meaning to model parameters.
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influence of non proportional loading on ratcheting responses and simulations by two recent cyclic plasticity models
International Journal of Plasticity, 2008Co-Authors: Tasnim Hassan, Lakhdar Taleb, Shree KrishnaAbstract:Abstract Aubin and her coworkers conducted a unique set of experiments demonstrating the influence of loading non-proportionality on ratcheting responses of duplex stainless steel. In order to further explore their new observation, a set of experiments was conducted on stainless steel (SS) 304L under various biaxial stress-controlled non-proportional histories. This new set of data reiterated Aubin and her coworkers’ observation and illustrated many new responses critical to model development and validation. Two recent and different classes of cyclic plasticity models, the modified Chaboche model proposed by Bari and Hassan and the version of the multi-mechanism model proposed by Taleb and Cailletaud, are evaluated in terms of their simulations of the SS304L non-proportional ratcheting responses. A modeling scheme for non-proportional ratcheting responses using the Kinematic Hardening Rule parameters in addition to the conventionally used isotropic Hardening Rule parameter (yield surface size change) in the modified Chaboche model is evaluated. Strengths and weaknesses of the models in simulating the non-proportional ratcheting responses are identified. Further improvements of these models needed for improving the non-proportional ratcheting simulations are suggested in the paper.
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anatomy of coupled constitutive models for ratcheting simulation
International Journal of Plasticity, 2000Co-Authors: Shafiqul Bari, Tasnim HassanAbstract:Abstract This paper critically evaluates the performance of five constitutive models in predicting ratcheting responses of carbon steel for a broad set of uniaxial and biaxial loading histories. The models proposed by Prager, Armstrong and Frederick, Chaboche, Ohno-Wang and Guionnet are examined. Reasons for success and failure in simulating ratcheting by these models are elaborated. The bilinear Prager and the nonlinear Armstrong-Frederick models are found to be inadequate in simulating ratcheting responses. The Chaboche and Ohno-Wang models perform quite well in predicting uniaxial ratcheting responses; however, they consistently overpredict the biaxial ratcheting responses. The Guionnet model simulates one set of biaxial ratcheting responses very well, but fails to simulate uniaxial and other biaxial ratcheting responses. Similar to many earlier studies, this study also indicates a strong influence of the Kinematic Hardening Rule or backstress direction on multiaxial ratcheting simulation. Incorporation of parameters dependent on multiaxial ratcheting responses, while dormant for uniaxial responses, into Chaboche-type Kinematic Hardening Rules may be conducive to improve their multiaxial ratcheting simulations. The uncoupling of the Kinematic Hardening Rule from the plastic modulus calculation is another potentially viable alternative. The best option to achieve a robust model for ratcheting simulations seems to be the incorporation of yield surface shape change (formative Hardening) in the cyclic plasticity model.
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on the performance of Kinematic Hardening Rules in predicting a class of biaxial ratcheting histories
International Journal of Plasticity, 1996Co-Authors: Edmundo Corona, Tasnim Hassan, Stelios KyriakidesAbstract:It is well known that strain-symmetric axial cycling of thin-walled metal tubes in the presence of pressure results in a progressive accumulation (ratcheting) of circumferential strain. It was previously demonstrated that the prediction of the rate of ratcheting under constant internal pressure, by nonlinear Kinematic Hardening models, is very sensitive to the Hardening Rule adopted. It was shown that the Armstrong-Frederick Hardening suitably calibrated and used in a class of models can yield reasonably good predictions of the rate of ratcheting for a range of cycle parameters. In this paper, the subject is revisited in the light of further experimental results involving simultaneous cycling of the internal pressure and the axial strain. Experiments and analyses were performed for a family of five such biaxial loading histories. A similar sensitivity to the Kinematic Hardening Rule used in the models was observed in all the new loading histories. Furthermore the Hardening Rule calibrated in the constant pressure experiments was found to yield accurate predictions for three of the loading histories considered and poor predictions for the other two. The reasons for this varied performance are analyzed and some recommendations for implementation of such models in structural applications are made.
