3D computational modeling of powder compaction processes using a three-invariant hardening cap plasticity model

In this paper, a three-invariant cap plasticity is developed for description of powder behavior under cold compaction process. The constitutive elasto-plastic matrix and its components are derived as the nonlinear functions of powder relative density. Different aspects of 2D and 3D cap plasticity models are illustrated and the procedure for determination of powder parameters is described. It is shown how the proposed model could generate the elliptical yield surface, double-surface cap plasticity and the irregular hexagonal pyramid of the Mohr-Coulomb and cone-cap yield surface, as special cases. The single-cap plasticity is performed within the framework of large finite element deformation, in order to predict the nonuniform relative density distribution during powder die pressing. Finally, the applicability of the proposed model for description of powder behavior is demonstrated in numerical simulation of triaxial and confining pressure tests. The numerical schemes are examined for efficiency in the modeling of an automotive component, a conical shaped-charge liner and a connecting-rod. (c) 2006 Elsevier B.V. All rights reserved.