An anisotropic model for the plastic response of powder compacts

In this paper we present an anisotropic compaction model based on a generic modeling framework. The model is a generalization of Hill's anisotropic model to compressible materials and reduces to a Cam-clay type model in the isotropic limit. The model has been calibrated using experimental data for a commercial steel powder obtained from a computer controlled triaxial cell in which the yield surface was probed following loading along different paths in stress and strain space. Closed-form analytical expressions are presented for the yield surface as a function of the inelastic strain. The model has been implemented in the general purpose finite element code ABAQUS. Simulations are presented which explore the effect of a detailed structure of the constitutive law on the compaction response.