Investigation of anisotropic plastic deformation of advanced high strength steel

Abstract

Influences of constitutive models on plastic behavior of a TRansformation Induced Plasticity (TRIP) high strength steel were investigated. Different yield criteria, the von Mises's isotropic, Hill's anisotropic (Hill'48) and Barlat's anisotropic (Yld2000-2d) function were taken into account. The hardening laws with regard to Swift and Voce model were examined. To determine material properties for different states of stress and loading directions, uniaxial tensile test, balanced biaxial test and disk compression test were performed. The yield stresses and r-values calculated according to the yield criteria were primarily compared with the experimental results. Afterwards, tensile test of sheet samples with various notch geometries as well as hole expansion test were carried out experimentally and simulated by the finite element method. Distributions of stress and strain within critical area of each notched sample were determined and effects of the yield functions and hardening models on the predicted stress triaxialities and plastic strain localizations were studied. In case of the hole expansion test, punch load and stroke, final hole diameter and strain distribution along the hole circumference and specimen diameter in the rolling and transverse directions were characterized and compared with the calculations. The anisotropic yield potential and hardening behavior significantly affected accuracies of the predicted local deformation behavior of the high strength steel sheet. It was shown that the Yld2000-2d model based on the Swift model with the exponent of six better agreed with the experimental data than other alternatives.