A Constitutive Model of Cyclic Plasticity for Nonlinear Hardening Materials

1986 ◽  
Vol 53 (2) ◽  
pp. 395-403 ◽  
Author(s):  
N. Ohno ◽  
Y. Kachi
Keyword(s):  
Constitutive Model ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Cyclic Plasticity ◽  
Elastoplastic Behavior ◽  
Surface Plasticity ◽  
Proposed Model ◽  
Cyclic Straining ◽  
Nonlinear Hardening ◽  
Mean Strain

A constitutive model is proposed for cyclic plasticity of nonlinear hardening materials. The concept of a cyclic nonhardening range, which enables us to describe the dependence of cyclic hardening on the amplitude of cyclic straining or stressing, is employed together with the idea of a two-surface plasticity model. Results of the proposed model are compared with experiments of 304 and 316 stainless steels in several cases of cyclic loading in which mean strain is zero or nonzero and strain limits are fixed or variable. Thus, it is shown that the model successfully describes both the cyclic hardening phenomenon and the transient elastoplastic behavior after initial and reverse yields of these materials. The capability of the model to provide nonlinear cyclic stress-strain curves is also discussed.

A Constitutive Model of Cyclic Plasticity With a Nonhardening Strain Region

1982 ◽  
Vol 49 (4) ◽  
pp. 721-727 ◽  
Author(s):  
N. Ohno
Keyword(s):  
Plastic Strain ◽  
Constitutive Model ◽  
Cyclic Creep ◽  
Cyclic Hardening ◽  
Present Theory ◽  
Cyclic Plasticity ◽  
304 Stainless Steel ◽  
Isotropic Hardening ◽  
Hardening Material ◽  
Cyclic Straining

By introducing the concept of a nonhardening region in the plastic strain space, a constitutive model is proposed for cyclic plastic loadings between variable, as well as fixed, strain limits. It is assumed that the isotropic hardening of materials does not occur when the plastic strain point moves inside this region after a load reversal. The region expands and translates as cyclic straining proceeds, and when strain limits are fixed, it eventually occupies the cyclic range of plastic strain so as to describe the saturation of cyclic hardening. The phenomena of cyclic relaxation and cyclic creep are also taken into account in the formulation. In the simple case of a linear hardening material, the present theory is verified by comparing predictions with experimental results on type 304 stainless steel under torsional cyclings between variable, as well as fixed, strain limits at room temperature.

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.

Modeling the Hydrogen Effect on the Constitutive Response of a Low Carbon Steel in Cyclic Loading

2020 ◽  
Vol 88 (3) ◽  
Author(s):  
Zahra S. Hosseini ◽  
Mohsen Dadfarnia ◽  
Akihide Nagao ◽  
Masanobu Kubota ◽  
Brian P. Somerday ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Cyclic Loading ◽  
Constitutive Model ◽  
Kinematic Hardening ◽  
Low Carbon Steel ◽  
Cyclic Hardening ◽  
Hydrogen Effect ◽  
Low Carbon ◽  
Japanese Industrial Standard ◽  
Cyclic Straining

Abstract Hydrogen-accelerated fatigue crack growth is a most severe manifestation of hydrogen embrittlement. A mechanistic and predictive model is still lacking partly due to the lack of a descriptive constitutive model of the hydrogen/material interaction at the macroscale under cyclic loading. Such a model could be used to assess the nature of the stress and strain fields in the neighborhood of a crack, a development that could potentially lead to the association of these fields with proper macroscopic parameters. Toward this goal, a constitutive model for cyclic response should be capable of capturing hardening or softening under cyclic straining or ratcheting under stress-controlled testing. In this work, we attempt a constitutive description by using data from uniaxial strain-controlled cyclic loading and stress-controlled ratcheting tests with a low carbon steel, Japanese Industrial Standard (JIS) SM490YB, conducted in air and 1 MPa H2 gas environment at room temperature. We explore the Chaboche constitutive model which is a nonlinear kinematic hardening model that was developed as an extension to the Frederick and Armstrong model, and propose an approach to calibrate the parameters involved. From the combined experimental data and the calibrated Chaboche model, we may conclude that hydrogen decreases the yield stress and the amount of cyclic hardening. On the other hand, hydrogen increases ratcheting, the rate of cyclic hardening, and promotes stronger recovery.

Mean Strain Effect on the Cyclic Stress-Strain Behavior of Steel Structure Materials Q235

2012 ◽  
Vol 602-604 ◽  
pp. 430-434 ◽  
Author(s):  
Yi Guo ◽  
Yun Rong Luo ◽  
Qing Yuan Wang
Keyword(s):  
Low Cycle Fatigue ◽  
Steel Structure ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Strain Effect ◽  
Cycle Fatigue ◽  
Q235 Steel ◽  
Strain Behavior ◽  
Mean Stress Relaxation ◽  
Mean Strain

The low cycle fatigue (LCF) behavior of Q235 steel under mean strain control has been investigated. A serious of the strain controlled cyclic loading experiments with several combinations of strain amplitudes and mean strains have been performed. Significant cyclic hardening and mean stress relaxation were observed in all cases. Fractography by scanning electron microscopy (SEM) was used to determine the LCF failure mechanisms and fatigue crack propagation modes of the Q235 steel.

scholarly journals An Isotropic Model for Cyclic Plasticity Calibrated on the Whole Shape of Hardening/Softening Evolution Curve

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 950 ◽  
Author(s):  
Jelena Srnec Novak ◽  
Francesco De Bona ◽  
Denis Benasciutti
Keyword(s):  
Finite Element ◽  
Copper Alloy ◽  
Cyclic Hardening ◽  
Uniaxial Stress ◽  
Cyclic Plasticity ◽  
Stress And Strain ◽  
Isotropic Model ◽  
Physical Behavior ◽  
Proposed Model ◽  
Kinematic Models

This work presents a new isotropic model to describe the cyclic hardening/softening plasticity behavior of metals. The model requires three parameters to be evaluated experimentally. The physical behavior of each parameter is explained by sensitivity analysis. Compared to the Voce model, the proposed isotropic model has one more parameter, which may provide a better fit to the experimental data. For the new model, the incremental plasticity equation is also derived; this allows the model to be implemented in finite element codes, and in combination with kinematic models (Armstrong and Frederick, Chaboche), if the material cyclic hardening/softening evolution needs to be described numerically. As an example, the proposed model is applied to the case of a cyclically loaded copper alloy. An error analysis confirms a significant improvement with respect to the usual Voce formulation. Finally, a numerical algorithm is developed to implement the proposed isotropic model, currently not available in finite element codes, and to make a comparison with other cyclic plasticity models in the case of uniaxial stress and strain-controlled loading.

A Novel Description of Thermomechanical Behavior Using a Rheological Model

2006 ◽  
Vol 306-308 ◽  
pp. 205-210 ◽  
Author(s):  
Keum Oh Lee ◽  
Seong Gu Hong ◽  
Soon Bok Lee
Keyword(s):  
Yield Stress ◽  
Rheological Model ◽  
Dynamic Recovery ◽  
Kinematic Hardening ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Thermomechanical Model ◽  
Stress Strain ◽  
Proposed Model ◽  
Thermomechanical Deformation

Isothermal cyclic stress-strain deformation and thermomechanical deformation (TMD) of 429EM stainless steel were analyzed using a rheological model employing a bi-linear model. The proposed model was composed of three parameters: elastic modulus, yield stress and flow stress. Monotonic stress-strain curves at various temperatures were used to construct the model. The yield stress in the model was nearly same as 0.2% offset yield stress. Hardening relation factor, m, was proposed to relate cyclic hardening to kinematic hardening. Isothermal cyclic stress-strain deformation could be described well by the proposed model. The model was extended to describe TMD. The results revealed that the bi-linear thermomechanical model overestimates the experimental data under both in-phase and out-of-phase conditions in the temperature range of 350-500oC and it was due to the enhanced dynamic recovery effect.

scholarly journals A Cyclic Plasticity Model with Martensite Transformation for S30408 and Its Finite Element Implementation

2020 ◽  
Vol 10 (17) ◽  
pp. 6002
Author(s):  
Yanan Chen ◽  
Xiaohui Chen ◽  
Bingjun Gao ◽  
Xu Chen ◽  
Kai Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Constitutive Model ◽  
Numerical Algorithm ◽  
Kinematic Hardening ◽  
Cyclic Plasticity ◽  
Flow Rule ◽  
Proposed Model ◽  
Metastable Austenitic Stainless Steel

The ability of the constitutive model to simulate the ratcheting behavior of metastable austenitic stainless steel S30408 is significant to ensure the safety of the liquefied natural gas (LNG) semi-trailer tanks in the lightweight process of the inner containers. This is because the lightweight inner vessels often encounter cyclic stresses due to the road inertia loads together with high mean stresses due to internal pressures. In this study, we performed cryogenic uniaxial tension experiments and a series of ratcheting experiments to investigate the cyclic plasticity behavior of the metastable austenitic stainless steel S30408. Based on the Ohno-Wang II model, we proposed a new cyclic plasticity constitutive model with martensitic transformation, which relates the content of deformation-induced martensite with isotropic hardening and kinematic hardening. The ratcheting behaviors of S30408 were first simulated by the proposed model with the incremental loading method using MATLAB. The results showed that the model could reasonably predict the ratcheting behavior of S30408, and the evolution law of martensite content could well predict the content of deformation-induced martensite. Under the assumption of the von Mises yield criterion and normal plasticity flow rule, we developed a numerical algorithm of plastic strain with the proposed model to implement the finite element calculation of the model. Internal iteration in the numerical algorithm was implemented with the Euler backward method, which calculated the trial strain for each equilibrium iteration using the consistent tangent matrix. With a user subroutine, the proposed model was programmed into ANSYS for a user - executable version. By simulating the uniaxial ratcheting of a S30408 round bar, we found that the calculated results were in good agreement with the experimental results, which promises further applications in the design of structures, such as LNG semi-trailer tanks.

Detailed and Simplified Elastoplastic Analyses of a Cyclically Loaded Notched Bar

1987 ◽  
Vol 109 (3) ◽  
pp. 194-202 ◽  
Author(s):  
N. Ohno ◽  
M. Sˇatra
Keyword(s):  
Detailed Analysis ◽  
Cyclic Load ◽  
Strain Curve ◽  
Cyclic Hardening ◽  
Cyclic Stress ◽  
Cyclic Plasticity ◽  
Stress And Strain ◽  
Plastic Behavior ◽  
Mean Values ◽  
Axial Cyclic Loading

To find some features in the development of cyclic hardening in structural components with areas of strain concentration, detailed and simplified elastoplastic analyses are performed on an axisymmetric notched bar subjected to axial cyclic loading. For the detailed analysis, the constitutive model based on the cyclic nonhardening region is implemented in an incremental FEM. The model can describe an important feature in cyclic plasticity, i.e., the dependence of cyclic plastic behavior on cyclic stress and strain ranges. The simplified method which utilizes the cylic stress-strain curve as the constitutive relation is applied to the case of nonzero as well as zero mean values of the cyclic load, and its validity is discussed on the basis of the results of the detailed analysis. The detailed analysis with accelerated cyclic hardening and the methods of Neuber and Stowell-Hardrath-Ohman are examined, too.

A unified viscoplastic description of 63Sn-37Pb solder alloy under cyclic straining and stressing

2004 ◽  
Vol 218 (9) ◽  
pp. 909-920 ◽  
Author(s):  
X J Yang ◽  
C L Chow ◽  
K J Lau
Keyword(s):  
Constitutive Model ◽  
Solder Alloy ◽  
Deformation Behaviour ◽  
Cyclic Strain ◽  
Cyclic Stress ◽  
Strain Rates ◽  
Viscoplastic Deformation ◽  
Stress Tests ◽  
Cyclic Tension ◽  
Cyclic Straining

A unified viscoplastic constitutive model for the fatigue life prediction of solder alloy 63Sn-37Pb is presented. The model incorporates the strain rate effect, the creep-plastic interaction and the dwell time effect under cyclic strain and stress loading. The applicability of this constitutive model is examined with cyclic strain tests with different strain rates, and cyclic stress tests under different stress waveforms in order to verify the progressive viscoplastic deformation of 63Sn-37Pb solder alloy. The investigation reveals that the material constants in the constitutive model can be determined by performing simple tests such as creep and cyclic tension-compression loading. The predictions using the constitutive model are found to agree well with the experimental results of the solder alloy under different loading. The agreement demonstrates that the model can satisfactorily describe the viscoplastic deformation behaviour under cyclic strain loading or stress loading.

Sign in / Sign up

Export Citation Format

Share Document