Enhancement of the Hoffman yield criterion with an anisotropic hardening model

In this paper, an anisotropic hardening model was proposed for the Hoffman yield criterion. Hardening is described via the introduction of a hardening function in which nine hardening parameters are utilized. Each hardening p arameter describes the hardening of its corresponding equivalent stress com ponent independently from the other hardening components. The resulting loc al return-mapping algorithm and the tangent stiffness matrix are derived. T he impact of this hardening hypothesis is studied with two benchmark tests. Furthermore, a modification of the model is introduced and its impact on t he benchmark tests is studied. (C) 2001 Elsevier Science Ltd. All rights re served.