Generation of Cyclic Stress-Strain Curves for Sheet Metals

2000 ◽  
Vol 123 (4) ◽  
pp. 391-397 ◽  
Author(s):  
K. M. Zhao ◽  
J. K. Lee
Keyword(s):  
Constitutive Model ◽  
Kinematic Hardening ◽  
Optimization Procedure ◽  
High Strength ◽  
Cyclic Stress ◽  
Bending Moments ◽  
Sheet Metals ◽  
Stress Strain ◽  
Normal Anisotropy ◽  
Material Parameters

The main objective of this paper is to obtain the first few stress-strain loops of sheet metals from reverse loading so that the springback can be simulated accurately. Material parameters are identified by an inverse method within a selected constitutive model that represents the hardening behavior of materials subjected to a cyclic loading. Three-point bending tests are conducted on sheet steels (mild steel and high strength steel). Punch stroke, punch load, bending strain, and bending angle are measured directly during the tests. Bending moments are then computed from these measured data. Bending moments are also calculated based on a constitutive model. Normal anisotropy and nonlinear isotropic/kinematic hardening are considered. Material parameters are identified by minimizing the normalized error between two bending moments. Micro-genetic algorithm is used in the optimization procedure. Stress-strain curves are generated with the material parameters found in this way, which can be used with other plastic models.

Generation of Cyclic Stress-Strain Curves for Sheet Metals

2000 ◽  
Author(s):  
K. M. Zhao ◽  
J. K. Lee
Keyword(s):  
Constitutive Model ◽  
Kinematic Hardening ◽  
Optimization Procedure ◽  
High Strength ◽  
Cyclic Stress ◽  
Bending Moments ◽  
Sheet Metals ◽  
Stress Strain ◽  
Normal Anisotropy ◽  
Material Parameters

Abstract The main objective of this paper is to generate cyclic stress-strain curves for sheet metals so that the springback can be simulated accurately. Material parameters are identified by an inverse method within a selected constitutive model that represents the hardening behavior of materials subjected to a cyclic loading. Three-point bending tests are conducted on sheet steels (mild steel and high strength steel). Punch stroke, punch load, bending strain and bending angle are measured directly during the tests. Bending moments are then computed from these measured data. Bending moments are also calculated based on a constitutive model. Normal anisotropy and nonlinear isotropic/kinematic hardening are considered. Material parameters are identified by minimizing the normalized error between two bending moments. Micro genetic algorithm is used in the optimization procedure. Stress-strain curves are generated with the material parameters found in this way, which can be used with other plastic models.

Material Properties of Aluminum Alloy for Accurate Draw-Bend Simulation

2001 ◽  
Vol 123 (3) ◽  
pp. 287-292 ◽  
Author(s):  
K. M. Zhao ◽  
J. K. Lee
Keyword(s):  
Kinematic Hardening ◽  
Optimization Procedure ◽  
Model Material ◽  
Bending Test ◽  
Aluminum Sheet ◽  
Isotropic Hardening ◽  
Bending Moments ◽  
Hardening Model ◽  
Material Parameters ◽  
Normalized Error

The main objective of this paper is to simulate springback using a combined kinematic/isotropic hardening model. Material parameters in the hardening model are identified by an inverse method. A three-point bending test is conducted on 6022-T4 aluminum sheet. Punch stroke, punch load, bending strain, and bending angle are measured directly during the tests. Bending moments are then computed from these measured data. Bending moments are also calculated based on a constitutive model. Material parameters are identified by minimizing the normalized error between two bending moments. A micro genetic algorithm is used in the optimization procedure. Stress-strain curves are generated with the material parameters found in this way, which can be used with other plasticity models. ABAQUS/Standard, which has the combined isotropic/kinematic hardening model, is used to simulate draw-bend of 6022-T4 aluminum sheet. Absolute springback angles are predicted very accurately.

Description of Closure of Cyclic Stress-Strain Loop and Ratcheting Based on Y-U Model

2016 ◽  
Vol 725 ◽  
pp. 351-356
Author(s):  
Fusahito Yoshida ◽  
Hiroshi Hamasaki ◽  
Takeshi Uemori
Keyword(s):  
Hysteresis Loop ◽  
Kinematic Hardening ◽  
Cyclic Stress ◽  
Cyclic Plasticity ◽  
Plasticity Model ◽  
Stress Strain ◽  
Additional Material ◽  
Material Parameters ◽  
Hardening Law ◽  
Cyclic Plasticity Model

This paper proposes a cyclic plasticity model to describe the closure of a cyclic stress-strain hysteresis loop based on the Y-U model. In this model, the backstress moves in a cyclic memory surface following a newly proposed kinematic hardening law. For this model just the same Y-U parameters can be used, and no additional material parameters are needed. By using a supplementary rule, this model is also able to describe ratcheting.

scholarly journals Identification of orthotropic material parameters for acute, necrotic, fibrotic and remodelling myocardial infarcts in the rat

2019 ◽  
Author(s):  
Mazin S. Sirry ◽  
Laura Dubuis ◽  
Neil H. Davies ◽  
Jun Liao ◽  
Thomas Franz
Keyword(s):  
Constitutive Model ◽  
Orthotropic Material ◽  
Constitutive Models ◽  
Biaxial Stress ◽  
Percentage Error ◽  
Fe Model ◽  
Stress Strain ◽  
Material Parameters ◽  
Strain Data ◽  
Tensile Experiment

AbstractFinite element (FE) models have been effectively utilized in studying biomechanical aspects of myocardial infarction (MI). Although the rat is a widely used animal model for MI, there is a lack of material parameters based on anisotropic constitutive models for rat myocardial infarcts in literature. This study aimed at employing inverse methods to identify the parameters of an orthotropic constitutive model for myocardial infarcts in the acute, necrotic, fibrotic and remodelling phases utilizing the biaxial mechanical data developed in a previous study. FE model was developed mimicking the setup of the biaxial tensile experiment. The orthotropic case of the generalized Fung constitutive model was utilized to model the material properties of the infarct. The parameters of Fung model were optimized so that the FE solution best fitted the biaxial experimental stress-strain data. A genetic algorithm was used to minimize the objective function. Fung orthotropic material parameters for different infarct stages were identified. The FE model predictions best approximated the experimental data of the 28 days infarct stage with 3.0% mean absolute percentage error. The worst approximation was for the 7 days stage with 3.6% error. This study demonstrated that the experimental biaxial stress-strain data of healing rat infarcts could be successfully approximated using inverse FE methods and genetic algorithms. The material parameters identified in this study will provide an essential platform for FE investigations of biomechanical aspects of MI and the development of therapies.

scholarly journals Micromechanical Modelling of the Cyclic Deformation Behavior of Martensitic SAE 4150—A Comparison of Different Kinematic Hardening Models

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 368 ◽  
Author(s):  
Benjamin Schäfer ◽  
Xiaochen Song ◽  
Petra Sonnweber-Ribic ◽  
Hamad ul Hassan ◽  
Alexander Hartmaier
Keyword(s):  
Kinematic Hardening ◽  
Three Dimensional ◽  
High Strength ◽  
Element Model ◽  
Calibration Procedure ◽  
Cyclic Stress ◽  
System Level ◽  
Strain Behavior ◽  
Hardening Models ◽  
Mean Stress Relaxation

A fundamental prerequisite for the micromechanical simulation of fatigue is the appropriate modelling of the effective cyclic properties of the considered material. Therefore, kinematic hardening formulations on the slip system level are of crucial importance due to their fundamental relevance in cyclic material modelling. The focus of this study is the comparison of three different kinematic hardening models (Armstrong Frederick, Chaboche, and Ohno–Wang). In this work, investigations are performed on the modelling and prediction of the cyclic stress-strain behavior of the martensitic high-strength steel SAE 4150 for two different total strain ratios (R ε = −1 and R ε = 0). In the first step, a three-dimensional martensitic microstructure model is developed by using multiscale Voronoi tessellations. Based on this martensitic representative volume element, micromechanical simulations are performed by a crystal plasticity finite element model. For the constitutive model calibration, a new multi-objective calibration procedure incorporating a sensitivity analysis as well as an evolutionary algorithm is presented. The numerical results of different kinematic hardening models are compared to experimental data with respect to the appropriate modelling of the Bauschinger effect and the mean stress relaxation behavior at R ε = 0. It is concluded that the Ohno–Wang model is superior to the Armstrong Frederick and Chaboche kinematic hardening model at R ε = −1 as well as at R ε = 0.

A Cyclic Stress-Strain Constitutive Model for Polycrystalline Magnesium Alloy and its Application

2007 ◽  
Vol 546-549 ◽  
pp. 81-88
Author(s):  
Xiang Guo Zeng ◽  
Qing Yuan Wang ◽  
Jing Hong Fan ◽  
Zhan Hua Gao ◽  
Xiang He Peng
Keyword(s):  
Magnesium Alloy ◽  
Constitutive Model ◽  
Cyclic Stress ◽  
Stress And Strain ◽  
Slip Systems ◽  
Stress Strain ◽  
Strain Behavior ◽  
Cast Magnesium ◽  
Magnesium Alloy Am60 ◽  
Good Agreement

The stress-strain behavior of cast magnesium alloy (AM60) was investigated by strain-controlled cyclic testing carried out on MTS. In order to describe the cyclic stress and strain properties of AM60 by means of the energy storing characteristics of microstructure during irreversible deformation, a plastic constitutive model with no yielding surface was developed for single crystal by adopting a spring-dashpot mechanical system. Plastic dashpots reflecting the material transient response were introduced to describe the plasticity of slip systems. By utilizing the KBW self-consistent theory, a polycrystalline plastic constitutive model for Magnesium alloy was formed. The numerical analysis in the corresponding algorithm is greatly simplified as no process of searching for the activation of the slip systems and slip directions is required. The cyclic stress-strain behavior, based on this model, is discussed. The simulation results show good agreement with the experimental data for AM60.

Determination of the Anisotropic Hardening of Sheet Metals at Large Strain from Stretch Bending Test

2016 ◽  
Vol 725 ◽  
pp. 677-682
Author(s):  
Gustavo Capilla ◽  
Hiroshi Hamasaki ◽  
Fusahito Yoshida ◽  
Toshiya Suzuki ◽  
Kazuo Okamura
Keyword(s):  
Large Strain ◽  
Rolling Direction ◽  
High Strength ◽  
Uniaxial Stress ◽  
Bending Test ◽  
Weighting Coefficient ◽  
Large Strains ◽  
Sheet Metals ◽  
Stress Strain ◽  
Stretch Bending

The present study aims to determine stress-strain curves at large strains of sheet metals under the uniaxial stress state by using the in-plane stretch-bending test. The combined Swift-Voce model, which describes the large-strain work-hardening of materials by means of a weighting coefficient μ, was used for FE simulation of the stretch-bending. The coefficient μ was determined by minimizing the difference in punch stroke vs. bending strain responses between the experimental data and the corresponding experimental results. By using this inverse approach, stress-strain curves of two levels of high-strength steel sheets of a precipitation hardening type, 590R and 780R, in three sheet directions (0, 45 and 90o from rolling direction), were determined.

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