A general yield function within the framework of linear transformations of stress tensors for the description of plastic-strain-induced anisotropy

A general yield function based on linear transformations of stress tensors for orthotropic sheet metals is presented to describe plastic strain-induced anisotropy. The subsequent anisotropy is considered by introducing a set of tensorial state variables in the linear transformations of stress tensors, and defining the tensorial state variables evolved with plastic deformation. The evolution of the tensorial state variables is based on eigen decomposition. The eigenvectors are normalized and used to represent the rotation of orthotropy axes of polycrystalline materials which relates to the texture rotation. The eigenvalues are used to capture the local reorientation of the grain preferred directions. Taking the anisotropic yield function Yld2000-2d as an example, the evolution of eigenvalues and eigenvectors of linear transformation tensors is investigated for AA3003-O aluminum alloy sheet. Based on the observations, a modified Yld2000-2d yield function incorporating with isotropic hardening model was developed to predict the anisotropy and subsequent yield surfaces in uni-axial tensions to confirm the validity of current yield function.1134sciescopu