Earing prediction of AA 2008-T4 with anisotropic Drucker yield function based on the second and third stress invariants

Abstract

This paper applies anisotropic Drucker yield function [14] (Lou and Yoon, 2018, Int. J. Plasticity 101, 125-55) to predict earing profile after cup deep drawing of AA 2008-T4. The new yield function is implemented into ABAQUS/Explicit using semi-implicit integration algorithm to calculate the increment of plastic strain. Both associated and non-associated flow rules are incorporated in this study. The predicted anisotropy and cup height profile are compared with the experimental results and those predicted from the Hill48, Yld91 and Yld2004-18p yield functions. It is observed that the earing profile predicted from the new yield function shows high accuracy. The computation time is also compared to investigate the computation cost of different yield functions. The comparison reveals that it takes the shortest time for the Hill48 function, the anisotropic Drucker yield function reduces 30%∼40% of computation cost compared with the Yld91 and Yld2004-18p functions. It is concluded from the simulation of cup deep drawing that the new yield function can provide high accurate numerical analysis of plastic deformation for anisotropic metals with competitive computation cost.