Viscoelastic–Viscoplastic Cyclic Deformation of Polycarbonate Polymer: Experiment and Constitutive Model

2016 ◽  
Vol 83 (4) ◽  
Author(s):  
Chao Yu ◽  
Guozheng Kang ◽  
Fucong Lu ◽  
Yilin Zhu ◽  
Kaijuan Chen
Keyword(s):  
Constitutive Model ◽  
Kinematic Hardening ◽  
Viscoelastic Model ◽  
Creep Recovery ◽  
Strong Nonlinearity ◽  
Viscoplastic Strain ◽  
Cyclic Tension ◽  
Nonlinear Viscoelastic ◽  
Tension Tests ◽  
Proposed Model

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.

Time-Dependent Uniaxial Ratchetting of Ultrahigh Molecular Weight Polyethylene Polymer: Viscoelastic–Viscoplastic Constitutive Model

2016 ◽  
Vol 83 (10) ◽  
Author(s):  
Kaijuan Chen ◽  
Guozheng Kang ◽  
Chao Yu ◽  
Fucong Lu ◽  
Han Jiang
Keyword(s):  
Molecular Weight ◽  
Constitutive Model ◽  
Viscoelastic Model ◽  
Hysteresis Loops ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Time Dependent ◽  
Creep Recovery ◽  
Tension Tests ◽  
Proposed Model ◽  
Ultrahigh Molecular Weight

Uniaxial tension–unloading recovery, creep-recovery, and stress-controlled cyclic tests are first performed to investigate the recoverable viscoelasticity and irrecoverable viscoplasticity (including the uniaxial ratchetting) of ultrahigh molecular weight polyethylene (UHMWPE) polymer at room temperature. The results show that obvious time-dependent ratchetting occurs in the asymmetrical stress-controlled cyclic tension–compression and tension–tension tests of the UHMWPE, and total ratchetting strain consists of both recoverable viscoelastic and irrecoverable viscoplastic parts. Based on the experimental observation, a new viscoelastic–viscoplastic constitutive model is proposed to describe the time-dependent ratchetting of the UHMWPE. In the proposed model, the viscoplastic strain is set to be contributed simultaneously by the unified viscoplastic and creep ones. Meanwhile, a memory surface is introduced into the viscoelastic model to improve the description to the shapes of stress–strain hysteresis loops. Finally, the proposed model is verified by comparing the predictions with the corresponding experimental results of the UHMWPE. It is clearly demonstrated that the proposed model predicts the creep, viscoelastic recovery, and uniaxial time-dependent ratchetting of the UHMWPE well.

scholarly journals A nonlinear viscoelastic–viscoplastic constitutive model for adhesives under creep

2021 ◽  
Author(s):  
Yi Chen ◽  
Lloyd V. Smith
Keyword(s):  
Yield Criterion ◽  
Kinematic Hardening ◽  
Viscoelastic Model ◽  
Three Dimensional ◽  
Creep Recovery ◽  
Element Analysis ◽  
Viscoplastic Model ◽  
Nonlinear Viscoelastic ◽  
Residual Strains ◽  
Scarf Joints

AbstractIn this study, we consider the nonlinear viscoelastic–viscoplastic behavior of adhesive films in scarf joints. We develop a three-dimensional nonlinear model, which combines a nonlinear viscoelastic model with a viscoplastic model using the von Mises yield criterion and nonlinear kinematic hardening. We implement an iterative scheme for the viscoplastic solution and a numerical algorithm with stress correction for the combined viscoelastic–viscoplastic model into finite element analysis. The viscoelastic component of the model is calibrated using creep-recovery data from adhesive films in scarf joints. The viscoplastic parameters are calibrated from the residual strains of recovered creep tests with varying load durations. A two-dimensional form of the model shows good agreement with the three-dimensional model for the scarf joint considered in this work and is compared with experiment. The numerical results show favorable agreement with the experimental creep and recovery responses of two epoxy adhesive systems. We also discuss the contribution of nonlinear viscoelasticity and viscoplasticity to the stress/strain distribution along the adhesive center lines. Viscoplasticity tends to lower the stress concentration.

On the Study of Cyclic Crystal Plasticity Ratchetting Constitutive Model for Polycrystalline Pure Copper

2019 ◽  
Vol 11 (04) ◽  
pp. 1950041 ◽  
Author(s):  
Yawei Dong ◽  
Dongyang Xie ◽  
Yang Zhang ◽  
Xiong Xiao
Keyword(s):  
Constitutive Model ◽  
Single Crystal ◽  
Kinematic Hardening ◽  
Pure Copper ◽  
Small Deformation ◽  
Cyclic Hardening ◽  
The Novel ◽  
Polycrystalline Metals ◽  
Proposed Model ◽  
Fcc Metal

With the hypothesis of a small deformation, the novel cyclic visco-plasticity constitutive model (CV-CM) is constructed to study the cyclic deformation responses of polycrystalline metals. In this model, a modified Armstrong–Frederick nonlinear kinematic hardening (NKH) law is adopted to simulate the ratchetting deformation more precisely. The cyclic hardening characteristic of FCC polycrystalline copper is investigated with the use of flow stress evolution of slip system. For the issue of the transition from single crystal to polycrystalline crystals, the explicit [Formula: see text] rule is introduced to compute the polycrystalline response. Finally, through comparison with the experimental data, the proposed model is verified. It is demonstrated that the uniaxial ratchetting response of FCC metal can be precisely captured. The ratchetting response of copper single crystal and its relation with the crystallographic directions can be exactly traced by the present model as well.

A Nonlinear Viscoelastic and Micromechanical Damage Constitutive Model for Solid Propellant

2013 ◽  
Vol 750-752 ◽  
pp. 2196-2199
Author(s):  
Zhi Xu Gu ◽  
Jian Zheng ◽  
Wei Peng ◽  
Xi Nan Tang ◽  
Jun Hui Yin
Keyword(s):  
Constitutive Model ◽  
Evolution Equation ◽  
Damage Evolution ◽  
Solid Propellant ◽  
Damage Evolution Equation ◽  
Nonlinear Viscoelastic ◽  
Tension Tests ◽  
Composite Solid Propellant ◽  
Damage Process ◽  
Viscoelastic Constitutive Model

This paper studies the damage process induced by dewetting microcracks in composite solid propellant. A nonlinear viscoelastic constitutive model for composite soild propellant is presented. The damage variable D is derived from the microcrack system and is function of microcrack size density. The damage evolution equation is determinded by the extending of microcrack. Form the proposed model of microrack evolution process, an explicit form of damage evolution equation which is a function of stress field is given. The cracking event N and the new crack surface area damage ΔA formed by microcrack extension are defined. Material constants are determinded by acoustic emission tests. The rationality of our model has been confirmed by tension tests.

Modeling the Ratcheting Phenomenon in an Austenitic Steel at Room Temperature

2000 ◽  
Author(s):  
A. S. Zaki ◽  
H. Ghonem
Keyword(s):  
Plastic Strain ◽  
Constitutive Model ◽  
Austenitic Steel ◽  
Room Temperature ◽  
Polycrystalline Material ◽  
Kinematic Hardening ◽  
Experimental Results ◽  
Experimental Program ◽  
Model Parameters ◽  
Proposed Model

Abstract This paper describes the cyclic accumulative plastic strain in a polycrystalline material when subjected to loading conditions promoting ratcheting behavior. For this purpose, a unified viscoplastic constitutive model based on non-linear kinematic hardening formulation is implemented. Identification of the model parameters was carried out using an experimental program that included monotonic, cyclic and relaxation testing. Simulation of the material response using the proposed model is compared with experimental results for the same loading. This comparison is used to evaluate the model validity.

A Straightforward Procedure to Characterize Nonlinear Viscoelastic Response of Asphalt Concrete at High Temperatures

2018 ◽  
Vol 2672 (28) ◽  
pp. 481-492 ◽  
Author(s):  
Mohammad Bazzaz ◽  
Masoud K. Darabi ◽  
Dallas N. Little ◽  
Navneet Garg
Keyword(s):  
Asphalt Concrete ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Deviatoric Stress ◽  
Creep Recovery ◽  
Viscoelastic Response ◽  
Nonlinear Viscoelastic ◽  
Wide Range ◽  
Stress Levels ◽  
Concrete Materials

This paper proposes a straightforward procedure to characterize the nonlinear viscoelastic response of asphalt concrete materials. Furthermore, a model is proposed to estimate the nonlinear viscoelastic parameters as a function of the triaxiality ratio, which accounts for both confinement and deviatoric stress levels. The simplified procedure allows for easy characterization of linear viscoelastic (LVE) and nonlinear viscoelastic (NVE) responses. First, Schapery’s nonlinear viscoelastic model is used to represent the viscoelastic behavior. Dynamic modulus tests are performed to calibrate LVE properties. Repeated creep-recovery tests at variable deviatoric stress levels (RCRT-VS) were designed and conducted to calibrate the nonlinear viscoelastic properties of four types of mixtures used in the Federal Aviation Administration’s National Airport Pavement and Materials Research Center test sections. The RCRT-VS were conducted at 55°C, 140 kPa initial confinement pressure, and wide range of deviatoric stress levels; mimicking the stress levels induced in a pavement structure under traffic. Once calibrated, the model was validated by comparing the model predictions and experimental measurements at different deviatoric stress levels. The predictions indicate that the proposed method is capable of characterizing NVE response of asphalt concrete materials.

A Phenomenological Constitutive Model Constructed for PC/ABS Blends

2006 ◽  
Vol 306-308 ◽  
pp. 989-994 ◽  
Author(s):  
M. Nizar Machmud ◽  
Masaki Omiya ◽  
Hirotsugu Inoue ◽  
Kikuo Kishimoto
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Constitutive Models ◽  
Strain Rates ◽  
Strain Behavior ◽  
Tension Tests ◽  
Proposed Model ◽  
Wide Range ◽  
Different Temperatures ◽  
Prediction Evaluation

Based on previous available constitutive models, a phenomenological constitutive model has been constructed and is proposed to describe the strain, strain rate and temperature dependentdeformation behavior of PC/ABS blends. In this paper, four quasi-static uniaxial tension tests of a specimen tested at different strain rates and temperatures were used to identify the constitutive model constants. By using the proposed constitutive model, predicting the stress-strain behavior of the PC/ABS blend tested at certain strain rate and different temperatures compares well to the behavior exhibited from the tests. From comparison between the DSGZ and the proposed models, proposed model shows a better prediction. Evaluation of the proposed constitutive model was also presented and it has revealed that the proposed model might have a potential to be used for predicting a wide range of temperatures and high strain rates behavior of PC/ABS blends.

Uniaxial Ratchetting of 316FR Steel at Room Temperature— Part I: Experiments

1999 ◽  
Vol 122 (1) ◽  
pp. 29-34 ◽  
Author(s):  
M. Mizuno ◽  
Y. Mima ◽  
M. Abdel-Karim ◽  
N. Ohno
Keyword(s):  
Plastic Strain ◽  
Room Temperature ◽  
Kinematic Hardening ◽  
Hysteresis Loops ◽  
Strain Range ◽  
Cyclic Hardening ◽  
Isotropic Hardening ◽  
Cyclic Tension ◽  
Tension Tests ◽  
Almost All

Uniaxial ratchetting characteristics of 316FR steel at room temperature are studied experimentally. Cyclic tension tests, in which maximum strain increases every cycle by prescribed amounts, are conducted systematically in addition to conventional monotonic, cyclic, and ratchetting tests. Thus hysteresis loop closure, cyclic hardening and viscoplasticity are discussed in the context of constitutive modeling for ratchetting. The cyclic tension tests reveal that very slight opening of hysteresis loops occurs, and that neither accumulated plastic strain nor maximum plastic strain induces significant isotropic hardening if strain range is relatively small. These findings are used to discuss the ratchetting tests. It is thus shown that uniaxial ratchetting of the material at room temperature is brought about by slight opening of hysteresis loops as well as by viscoplasticity, and that kinematic hardening governs almost all strain hardening in uniaxial ratchetting if stress range is not large. [S0094-4289(00)00401-1]

Off-Axis Creep Recovery of Unidirectional Carbon/Epoxy Composites at High Temperature

2007 ◽  
Vol 334-335 ◽  
pp. 65-68 ◽  
Author(s):  
Masamichi Kawai ◽  
H. Kamioka ◽  
Jian Qi Zhang ◽  
Tetsuya Matsuda
Keyword(s):  
High Temperature ◽  
Creep Strain ◽  
Composite System ◽  
Kinematic Hardening ◽  
High Stress ◽  
Unidirectional Composite ◽  
Constant Stress ◽  
Creep Recovery ◽  
Creep Stress ◽  
Proposed Model

Off-axis creep recovery behavior after complete unloading during creep at a constant stress is examined for a unidirectional T800H/3631 carbon/epoxy composite laminate at high temperature. Creep and creep recovery tests are performed on plain coupon specimens with four kinds of fiber orientations: 10, 30, 45 and 90°. It is observed that the creep strain appeared at a high stress does not completely recover after full removal of the creep stress, indicating that an irrecoverable creep strain has developed under the prior constant stress loading. Variable stress creep simulations are attempted using the modified kinematic hardening model for homogenized anisotropic inelastic composites in which an accelerated change in kinematic hardening over a certain range of viscoplastic strain is considered. Comparison with experimental results demonstrates that the proposed model can adequately describe the off-axis creep and creep recovery behaviors of the unidirectional composite system under constant and variable stress conditions.

A thermodynamically consistent viscoelastic–viscoplastic constitutive model for self-healing materials

2017 ◽  
Vol 29 (6) ◽  
pp. 1065-1080 ◽  
Author(s):  
Hamid Shahsavari ◽  
Mostafa Baghani ◽  
Reza Naghdabadi ◽  
Saeed Sohrabpour
Keyword(s):  
Constitutive Model ◽  
Evolution Equations ◽  
Model Development ◽  
Irreversible Processes ◽  
Creep Recovery ◽  
Self Healing ◽  
Energy Equivalence ◽  
Proposed Model ◽  
Damage Healing ◽  
Strain Tensors

Self-healing materials, as a class of intelligent materials, are capable to recover a part of the weakened mechanical properties induced by damage. In this article, based on the thermodynamics of irreversible processes, employing the effective configuration in the continuum damage-healing mechanics, a viscoelastic–viscoplastic constitutive model is presented. In the constitutive model development, we adopt an additive decomposition of the total strain into elastic, viscoelastic, and viscoplastic parts. In this regard, defining the damage and healing variables and employing the strain energy equivalence hypothesis, stress and strain tensors in the effective configuration are obtained. Satisfying the Clausius–Duhem inequality, the evolution equations are introduced for viscoelastic and viscoplastic strains. The damage and healing variables also evolve according to two different evolutions. To employ the proposed model in different loading conditions, the time-discrete form of the model in the semi-implicit form is presented. Material parameters of the model are identified with creep, creep-recovery, and repeated creep-recovery tests on asphalt concrete materials in the literature. Finally, the capability of the proposed model is demonstrated applying the model prediction for creep-recovery and repeated creep-recovery case studies and comparing the results with the experimental data available in the literature.

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