Unconditionally convex yield functions for sheet metal forming based on linear stress deviator transformation

Abstract

Two non-quadratic orthotropic yield functions called Yld2011-18p (containing 18 parameters) and Yld2011-27p (containing 27 parameters) are proposed. The formulations are based on the established concept of linear transformations operating on the stress deviator. Application examples reveal the capabilities of both yield functions to accurately describe complex plastic anisotropy of sheet metals.