Comparison of various plasticity models for metal powder compaction processes

The computer-based process simulation of powder metal (PM) components requires suitable material model to describe the deformation behavior in order to examine the effects of parametric variation. Over the years, several plasticity models with various yield function coefficients have been proposed (Eq. (2)), but the qualitative performance are, hitherto, unavailable in open literature, to the best of author's knowledge. In this context, an elastic-plastic finite element program within the framework of associative plasticity under monotonic load histories has been developed to examine the role of yield function coefficients for powder compaction process. An infinitesimal deformation theory involving material non-linearity for solid-based formulations, suitably modeled to admit linear work hardening of materials, has been used to describe the consolidation process. Considering incremental flow rule, and using elements with different displacement distributions, the deformation characteristics have been examined. The numerical experiments performed demonstrate that the solutions obtained by using the relation (2) yield nearly identical results at higher load levels. However, some marginal discrepancies are also reflected in some of the solutions at lower load ranges and are reported here. (c) 2004 Elsevier B.V. All rights reserved.