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Yichao Chen - One of the best experts on this subject based on the ideXlab platform.

  • analysis of the finite Deformation Response of shape memory polymers ii 1d calibration and numerical implementation of a finite Deformation thermoelastic model
    Smart Materials and Structures, 2010
    Co-Authors: Brent Louis Volk, Dimitris C Lagoudas, Yichao Chen
    Abstract:

    This study presents the analysis of the finite Deformation Response of a shape memory polymer (SMP). This two-part paper addresses the thermomechanical characterization of SMPs, the derivation of material parameters for a finite Deformation phenomenological model, the numerical implementation of such a model, and the predictions from the model with comparisons to experimental data. Part II of this work presents the calibration of a previously developed thermoelastic constitutive model which is capable of handling finite Deformations. The model is proposed in a general three-dimensional framework; however, this work focuses on reducing the model to one dimension and subsequently calibrating the model using experimental data obtained in part I. The one-dimensional numerical implementation of the model is presented, including the handling of the system of nonlinear equations and the integral term resulting from the constitutive model. The model is then used to predict the uniaxial shape memory effect. Results indicate good agreement between the model predictions and the experimental results, but the predictions do not capture the irrecoverable Deformation present at the end of recovery.

  • Analysis of the finite Deformation Response of shape memory polymers: I. Thermomechanical characterization
    Smart Materials and Structures, 2010
    Co-Authors: Brent Louis Volk, Yichao Chen, Dimitris C Lagoudas, Karen S. Whitley
    Abstract:

    This study presents the analysis of the finite Deformation Response of a shape memory polymer (SMP). This two-part paper addresses the thermomechanical characterization of SMPs, the derivation of material parameters for a finite Deformation phenomenological model, the numerical implementation of such a model, and the predictions from the model with comparisons to experimental data. Part I of this work presents the thermomechanical characterization of the material behavior of a shape memory polymer. In this experimental investigation, the vision image correlation system, a visual–photographic apparatus, was used to measure displacements in the gauge area. A series of tensile tests, which included nominal values of the extension of 10%, 25%, 50%, and 100%, were performed on SMP specimens. The effects on the free recovery behavior of increasing the value of the applied Deformation and temperature rate were considered. The stress–extension relationship was observed to be nonlinear for increasing values of the extension, and the shape recovery was observed to occur at higher temperatures upon increasing the temperature rate. The experimental results, aided by the advanced experimental apparatus, present components of the material behavior which are critical for the development and calibration of models to describe the Response of SMPs.

Brent Louis Volk - One of the best experts on this subject based on the ideXlab platform.

  • analysis of the finite Deformation Response of shape memory polymers ii 1d calibration and numerical implementation of a finite Deformation thermoelastic model
    Smart Materials and Structures, 2010
    Co-Authors: Brent Louis Volk, Dimitris C Lagoudas, Yichao Chen
    Abstract:

    This study presents the analysis of the finite Deformation Response of a shape memory polymer (SMP). This two-part paper addresses the thermomechanical characterization of SMPs, the derivation of material parameters for a finite Deformation phenomenological model, the numerical implementation of such a model, and the predictions from the model with comparisons to experimental data. Part II of this work presents the calibration of a previously developed thermoelastic constitutive model which is capable of handling finite Deformations. The model is proposed in a general three-dimensional framework; however, this work focuses on reducing the model to one dimension and subsequently calibrating the model using experimental data obtained in part I. The one-dimensional numerical implementation of the model is presented, including the handling of the system of nonlinear equations and the integral term resulting from the constitutive model. The model is then used to predict the uniaxial shape memory effect. Results indicate good agreement between the model predictions and the experimental results, but the predictions do not capture the irrecoverable Deformation present at the end of recovery.

  • Analysis of the finite Deformation Response of shape memory polymers: I. Thermomechanical characterization
    Smart Materials and Structures, 2010
    Co-Authors: Brent Louis Volk, Yichao Chen, Dimitris C Lagoudas, Karen S. Whitley
    Abstract:

    This study presents the analysis of the finite Deformation Response of a shape memory polymer (SMP). This two-part paper addresses the thermomechanical characterization of SMPs, the derivation of material parameters for a finite Deformation phenomenological model, the numerical implementation of such a model, and the predictions from the model with comparisons to experimental data. Part I of this work presents the thermomechanical characterization of the material behavior of a shape memory polymer. In this experimental investigation, the vision image correlation system, a visual–photographic apparatus, was used to measure displacements in the gauge area. A series of tensile tests, which included nominal values of the extension of 10%, 25%, 50%, and 100%, were performed on SMP specimens. The effects on the free recovery behavior of increasing the value of the applied Deformation and temperature rate were considered. The stress–extension relationship was observed to be nonlinear for increasing values of the extension, and the shape recovery was observed to occur at higher temperatures upon increasing the temperature rate. The experimental results, aided by the advanced experimental apparatus, present components of the material behavior which are critical for the development and calibration of models to describe the Response of SMPs.

Kemin Xue - One of the best experts on this subject based on the ideXlab platform.

  • cyclic Deformation Response and micromechanisms of ti alloy ti 5al 5v 5mo 3cr 0 5fe
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011
    Co-Authors: Jun Huang, Zhirui Wang, Kemin Xue
    Abstract:

    Abstract Cyclic Deformation Response of Ti-5553 alloy with β–α bimodal structure is systematically studied through total strain controlled fatigue tests. Results on the relationship between mechanical Response and microstructure evolution are presented in this report. It was found that cyclic hardening/softening behavior of the alloy depended strongly on the applied strain amplitude. At low strain levels, the material showed moderate hardening behavior at the early stage of cycling and then behaved elastically; whereas at high strain amplitudes, the alloy showed softening behavior from the beginning to the end of cycling. In the intermediate strain range, moderate hardening at the beginning followed by softening was detected. Transmission electron microscopy investigation revealed that such special macroscopic Responses were due to the microstructure heterogeneity in the material. The activation and participation in the cyclic Deformation of different constituents, namely the soft primary α p phase, the higher strength transformed β phase and the fine embedded α s precipitates in the β matrix played different roles at different strain levels and at different stages of cycling. Thus, the aforementioned specific cyclic hardening/softening behavior was introduced. Specifically, dislocation activities including activation of multiple slip systems and annihilation of pre-existing dislocations in the primary α p phase were found to play a very important role in the overall cyclic Deformation behavior.

  • Cyclic Deformation Response and micromechanisms of Ti alloy Ti–5Al–5V–5Mo–3Cr–0.5Fe
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011
    Co-Authors: Jun Huang, Zhirui Wang, Kemin Xue
    Abstract:

    Abstract Cyclic Deformation Response of Ti-5553 alloy with β–α bimodal structure is systematically studied through total strain controlled fatigue tests. Results on the relationship between mechanical Response and microstructure evolution are presented in this report. It was found that cyclic hardening/softening behavior of the alloy depended strongly on the applied strain amplitude. At low strain levels, the material showed moderate hardening behavior at the early stage of cycling and then behaved elastically; whereas at high strain amplitudes, the alloy showed softening behavior from the beginning to the end of cycling. In the intermediate strain range, moderate hardening at the beginning followed by softening was detected. Transmission electron microscopy investigation revealed that such special macroscopic Responses were due to the microstructure heterogeneity in the material. The activation and participation in the cyclic Deformation of different constituents, namely the soft primary α p phase, the higher strength transformed β phase and the fine embedded α s precipitates in the β matrix played different roles at different strain levels and at different stages of cycling. Thus, the aforementioned specific cyclic hardening/softening behavior was introduced. Specifically, dislocation activities including activation of multiple slip systems and annihilation of pre-existing dislocations in the primary α p phase were found to play a very important role in the overall cyclic Deformation behavior.

C G Yang - One of the best experts on this subject based on the ideXlab platform.

  • the significance of phase reversion induced nanograined ultrafine grained structure on the load controlled Deformation Response and related mechanism in copper bearing austenitic stainless steel
    Journal of The Mechanical Behavior of Biomedical Materials, 2020
    Co-Authors: C Y Hu, Mahesh C. Somani, R D K Misra, C G Yang
    Abstract:

    Abstract The ingenious concept of phase reversion annealing involving cold Deformation of parent austenite to strain-induced martensite, followed by annealing was used to obtain nano-grained/ultrafine-grained (NG/UFG) structure in a Cu-bearing biomedical austenitic stainless steel resulting in high strength-high ductility combination. Having employed the concept effectively, the primary objective of this study is to critically analyze the interplay between the load-controlled Deformation Response, strain-rate sensitivity and Deformation mechanism of NG/UFG austenitic stainless steel via nanoscale Deformation experiments and compare with its coarse-grained (CG) counterpart. The study demonstrated that the strain-rate sensitivity of NG/UFG was ~1.5 times that of the CG structure. Post-mortem electron microscopy of plastic zone surrounding the indents indicated that the active Deformation mechanism was nanoscale twinning with typical characteristics of a network of intersecting twins in the NG/UFG structure, while strain-induced martensite transformation was the effective Deformation mechanism for the CG structure. The fracture morphology was also different for the two steels, essentially ductile in nature, and was characterized by striations marking the line-up of voids in NG/UFG steel and microvoid coalescence in CG counterpart. The differences in Deformation mechanisms between the NG/UFG and CG structure are attributed to the austenite stability – strain energy relationship. Furthermore, the presence of ~3 wt % Cu in austenitic stainless steel had somewhat moderate effect on strain-rate sensitivity and activation volume at similar level of grain size in its Cu-free counterpart. Specifically, in the NG/UFG structure, the nanoscale twin density was noticeably higher in Cu-bearing austenitic stainless steel as compared to Cu-free counterpart, as Cu is known to increase the stacking fault energy.

  • The significance of phase reversion-induced nanograined/ultrafine-grained structure on the load-controlled Deformation Response and related mechanism in copper-bearing austenitic stainless steel
    Journal of The Mechanical Behavior of Biomedical Materials, 2020
    Co-Authors: C Y Hu, Mahesh C. Somani, R D K Misra, C G Yang
    Abstract:

    Abstract The ingenious concept of phase reversion annealing involving cold Deformation of parent austenite to strain-induced martensite, followed by annealing was used to obtain nano-grained/ultrafine-grained (NG/UFG) structure in a Cu-bearing biomedical austenitic stainless steel resulting in high strength-high ductility combination. Having employed the concept effectively, the primary objective of this study is to critically analyze the interplay between the load-controlled Deformation Response, strain-rate sensitivity and Deformation mechanism of NG/UFG austenitic stainless steel via nanoscale Deformation experiments and compare with its coarse-grained (CG) counterpart. The study demonstrated that the strain-rate sensitivity of NG/UFG was ~1.5 times that of the CG structure. Post-mortem electron microscopy of plastic zone surrounding the indents indicated that the active Deformation mechanism was nanoscale twinning with typical characteristics of a network of intersecting twins in the NG/UFG structure, while strain-induced martensite transformation was the effective Deformation mechanism for the CG structure. The fracture morphology was also different for the two steels, essentially ductile in nature, and was characterized by striations marking the line-up of voids in NG/UFG steel and microvoid coalescence in CG counterpart. The differences in Deformation mechanisms between the NG/UFG and CG structure are attributed to the austenite stability – strain energy relationship. Furthermore, the presence of ~3 wt % Cu in austenitic stainless steel had somewhat moderate effect on strain-rate sensitivity and activation volume at similar level of grain size in its Cu-free counterpart. Specifically, in the NG/UFG structure, the nanoscale twin density was noticeably higher in Cu-bearing austenitic stainless steel as compared to Cu-free counterpart, as Cu is known to increase the stacking fault energy.

Dimitris C Lagoudas - One of the best experts on this subject based on the ideXlab platform.

  • analysis of the finite Deformation Response of shape memory polymers ii 1d calibration and numerical implementation of a finite Deformation thermoelastic model
    Smart Materials and Structures, 2010
    Co-Authors: Brent Louis Volk, Dimitris C Lagoudas, Yichao Chen
    Abstract:

    This study presents the analysis of the finite Deformation Response of a shape memory polymer (SMP). This two-part paper addresses the thermomechanical characterization of SMPs, the derivation of material parameters for a finite Deformation phenomenological model, the numerical implementation of such a model, and the predictions from the model with comparisons to experimental data. Part II of this work presents the calibration of a previously developed thermoelastic constitutive model which is capable of handling finite Deformations. The model is proposed in a general three-dimensional framework; however, this work focuses on reducing the model to one dimension and subsequently calibrating the model using experimental data obtained in part I. The one-dimensional numerical implementation of the model is presented, including the handling of the system of nonlinear equations and the integral term resulting from the constitutive model. The model is then used to predict the uniaxial shape memory effect. Results indicate good agreement between the model predictions and the experimental results, but the predictions do not capture the irrecoverable Deformation present at the end of recovery.

  • Analysis of the finite Deformation Response of shape memory polymers: I. Thermomechanical characterization
    Smart Materials and Structures, 2010
    Co-Authors: Brent Louis Volk, Yichao Chen, Dimitris C Lagoudas, Karen S. Whitley
    Abstract:

    This study presents the analysis of the finite Deformation Response of a shape memory polymer (SMP). This two-part paper addresses the thermomechanical characterization of SMPs, the derivation of material parameters for a finite Deformation phenomenological model, the numerical implementation of such a model, and the predictions from the model with comparisons to experimental data. Part I of this work presents the thermomechanical characterization of the material behavior of a shape memory polymer. In this experimental investigation, the vision image correlation system, a visual–photographic apparatus, was used to measure displacements in the gauge area. A series of tensile tests, which included nominal values of the extension of 10%, 25%, 50%, and 100%, were performed on SMP specimens. The effects on the free recovery behavior of increasing the value of the applied Deformation and temperature rate were considered. The stress–extension relationship was observed to be nonlinear for increasing values of the extension, and the shape recovery was observed to occur at higher temperatures upon increasing the temperature rate. The experimental results, aided by the advanced experimental apparatus, present components of the material behavior which are critical for the development and calibration of models to describe the Response of SMPs.