On the use of HCP and FCC RVE structures in the simulation of powder compaction

Abstract

Use of hexagonal close packed and face centered cubic structures to simulate powder compaction reveals that plastic deformation is effective in reducing porosity until a relative density of 0.96, beyond which a drastic rise in pressure is required. The compaction process can be divided into three phases demarcated by relative densities of 0.8 and 0.92, characterized, respectively, by local yielding around the initial contact point, coalescence of locally yielded zones and full plastic flow to reduce pores. The macroscopic yield behaviour of the powder assembly in the present work agrees reasonably with analytical and numerical models such as the Storåkers-Fleck-McMeeking model and multi-particle finite element model. It is found that for rate-dependent powder materials, the compaction process is noticeably rate dependent from a relative density of 0.85. Although a regular packing of powders is unrealistic, the understanding gained from a regular packing model provides insight into the role that plastic deformation plays during powder compaction.