Finite element simulation of compaction

This paper reviews the modeling of constitutive behavior of powders. The plasticity equations and elastic properties of powders and green compacts are described briefly. As an example, the simulation of die-compaction of an axisymmetric multi-stepped part made from iron powder is considered. The effects of tool kinematics on the occurrence of slip-crack and density distribution are investigated. It is shown that there is a critical compression ratio in the rim of the part relative to that in the hub in which a slip-crack defect occurs, and that the critical compression ratio increases with increasing friction at the powder-tool interfaces. Simulation is also performed for rubber isostatic pressing to understand its fundamental features. Based on the simulation, an algorithm is developed for optimizing the mold cavity shape that gives the desired compact shape.