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 parameter describes the hardening of its corresponding equivalent stress component independently from the other hardening components. The resulting local return-mapping algorithm and the tangent stiffness matrix are derived. The impact of this hardening hypothesis is studied with two benchmark tests. Furthermore, a modification of the model is introduced and its impact on the benchmark tests is studied.