Plastic instability in complex strain paths predicted by advanced constitutive equations

The present paper aims at predicting plastic instabilities under complex loading histories using an advanced sheet metal forming limit model. The onset of localized necking is computed using the Marciniak-Kuczinslcy (MK) analysis [I] with a physically-based hardening model and the phenomenological anisotropic yield criterion Yld2000-2d [2]. The hardening model accounts for anisotropic work-hardening induced by the microstructural evolution at large strains, which was proposed by Teodosiu and Hu [3]. Simulations are carried out for linear and complex strain paths. Experimentally, two deep-drawing quality sheet metals are selected: a bake-hardening steel (BH) and a DC06 steel sheet. The validity of the model is assessed by comparing the predicted and experimental forming limits. The remarkable accuracy of the developed software to predict the forming limits under linear and non-linear strain path is obviously due to the performance of the advanced constitutive equations to describe with great detail the material behavior. The effect of strain-induced anisotropy on formability evolution under strain path changes, as predicted by the microstructural hardening model, is particularly well captured by the model.open1134Nsciescopu

Study on plastic flow localization prediction using a physically-based hardening model

The present paper aims at a detailed analysis of sheet metal formability using the physically-based hardening model accounting for the evolution of the anisotropic work-hardening induced by the microstructural evolution at large strains of Teodosiu and Hu (1995) [9]. The onset of localized necking is simulated by an advanced sheet metal forming limit model which connects, through the Marciniak-Kuczinsky analysis, the respective microstructural hardening model with the phenomenological anisotropic yield criterion Yld2000-2d (Barlat et al., 2003) [17]. Linear and complex strain paths are taken into account. The selected material is a DC06 steel sheet. An exhaustive study on the evolution of internal variables of the microstructural hardening model under such loadings is presented. The origin of the increase/decrease of formability under specific strain path changes is discussed. (C) 2011 Elsevier B.V. All rights reserved.X1132sciescopu

Sheet metal forming limit predictions based on advanced constitutive equations

The present paper aims at analysing the strain and stress-based forming limits predicted by an advanced sheet metal forming limit model. The onset of localized necking is simulated through the Marciniak-Kuczinsky (MK) analysis [1]., which connects the physically-based hardening model accounting for the evolution of the anisotropic work-hardening induced by the microstructural evolution at large strains of Teodosiu and Hu [2] with the phenomenological anisotropic yield criterion Yld2000-2d (Barlat et al., 2003) [3] Linear and complex strain paths are taken into account. The selected material is a DC06 steel sheet. The validity of the model is assessed by comparing the predicted and experimental forming limits. The remarkable accuracy of the developed software on predicting the forming limits is obviously due to the performance of the advanced constitutive equations applied on M-K theory, able to describe with great detail the material behaviour. The effect of the strain-induced anisotropy predicted by the microstructural hardening model on the evolution of formability under strain path changes is particularly aimed it.X111sciescopu

Analysis of sheet metal formability through isotropic and kinematic hardening models

The present paper aims at analysing the sheet metal formability through several isotropic and kinematic hardening models. Specifically, a special attention is paid to the physically-based hardening model of Teodosiu and Hu (1995), which accounts for the anisotropic work-hardening induced by the microstructural evolution at large strains, as well as to some more conventional hardening models, including the isotropic Swift strain-hardening power law, and the Voce saturation strain-hardening law, combined with a non-linear kinematic hardening described by the Armstrong-Frederick law. The onset of localized necking is simulated by an advanced sheet metal forming limit model which connects, through the Marciniak-Kuczinsky analysis, the hardening models with the anisotropic yield criterion Y1d2000-2d (Barlat et al., 2003). Both linear and complex strain paths are taken into account. The selected material is a DC06 steel sheet. The validity of each model is assessed by comparing the predicted forming limits with experimental results carefully obtained on this steel. The origin of discrepancy in the predicted results using different hardening models is thoroughly analyzed. (C) 2011 Elsevier Masson SAS. All rights reserved.X111816sciescopu

A new model for FLD prediction based on advanced constitutive equations

An advanced sheet metal forming limit model is developed. Using the Marciniak-Kuczinsky analysis, this approach intends to join advantages of physics-based aspects of plasticity with advantages of phenomenological material description. It aims thus at connecting the most advanced physically-based hardening model accounting for the evolution of the anisotropic work hardening induced by the microstructural evolution at large strains of Teodosiu and Hu (1995) with the advanced phenomenological anisotropic yield criterion Yld2000-2d (Barlat et al. Int J Plast 19: 1297-1319, 2003). Two deep-drawing quality sheet metals are selected: a bake-hardening steel (BH) and AA6016-T4 aluminium alloy. Linear and complex strain paths are taken into account. By comparing the simulated and experimental results the model is validated.X11810sciescopu

Experiments and Modeling of Low Carbon Steel Sheet Subjected to Double Strain Path Changes

Low carbon steel was deformed under double strain path changes consisting in three successive tension tests carried out in different directions with respect to the material symmetry axes. The influences of the strain amounts and severity of strain path change in the reloading yield stress and subsequent strain hardening were investigated in detail. The trends captured using the homogeneous anisotropic hardening approach, which is based on a homogeneous yield function, are in good agreement with the experimental results.open118sciescopu