Anisotropic plasticity and fracture modelling of cold rolled AA5754

Abstract

The effect of the anisotropy, the loading rate and stress state on the ductile fracture of AA5754 cold-rolled sheets has been investigated. The plasticity has been analysed experimentally testing biaxial and uniaxial tensile specimens machined at several orientations with respect to the rolling direction and calibrating the Yld2000-3D yield criterion. The strain rate dependency of the material has been evaluated testing notched tension specimens at different loading rates. The resulting force–displacement curves, showing negative loading rate sensitivity, have been employed to identify the work hardening constants of a modified isotropic rate-dependent law through inverse modelling. Finite element simulations of the experiments on central hole, notched, shear and biaxial specimens conducted at several loading rates and orientations, monitored with three-dimensional digital image correlation, have been performed to obtain the Cauchy stress and equivalent plastic strain histories from the critical elements located where fracture is observed in such experiments. The anisotropic Hosford-Coulomb fracture initiation criterion has been modified to accommodate the loading rate effects giving reasonable failure predictions.