Analysis of Dynamic Powder Compaction for the Metallic Powder Introducing Malvern-Type Constitutive Equation

In powder Metallurgy process, some dynamic powder compaction methods have been proposed because they have advantages of giving uniform density distribution even for high-aspect-ratio parts and breaking surface oxides of powders, comparing with static powder compaction methods.Constitutive equations considering strain-rate effect are usually used to analyze the dynamic deformation of solid materials. One-dimensional dynamic analyses using static stress-strain relations were carried out so far. However, in case of powder materials, constitutive equation considering the strain-rate effect has not been applied.In this paper a Malvern-Type constitutive equation, Ee=σ+K(σ-f(e)) for powder materials is employed to analyze dynamic behavior of powder materials. A constant, K, in the equation is obtained by comparing the experimental and analytical results in terms of plastic strain distribution at longitudinal in a container. In the case of rapidly solidified Al-Li powder, K=2×105 is obtained.This method can widely be applicable to get dynamic constitutive equations for powders.