Estimation of Stress Distribution Arising in a Powder Bed during Compaction by FEM considering Anisotropic Parameters [Translated]†

Abstract

Stress analysis on the compaction of ceramic powder was performed by the finite element method (FEM) to predict the optimum conditions. For the purpose of practical application, the powder bed was treated as an elastoplastic material, and the constitutive equation was derived from DruckerPrager's yield function expressed in terms of invariants of stress tensors and Hill's anisotropic parameters on stress in the powder bed. The powder bed has a multiform bulk density distribution, along with discontinuous deformation behavior during compression, which change the mechanical characteristics of the powder bed during compaction. It is therefore necessary to treat powder characteristics as variation associated with the progress of powder compaction. In this paper, Young's modulus and the strain-hardening rate are expressed as functions of minor principal stress and strain. These functions can be determined by a triaxial compression test. Hill's anisotropy parameters, which are induced during the compaction process, were numerically obtained by simulating the compacting behavior of particles using the particle element method (PEM). The problem of powder compaction was analyzed on the basis of the proposed constitutive model. The calculated results of the nonlinear stress-strain relation and stress distribution during powder compaction agreed well with the measured values. Results showed that the proposed procedure offers information that is useful in deciding the optimum conditions for powder compaction.† This report was originally printed in Kagaku Kogaku Ronbunshu, 26(1), 23-30 (2000) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Chemical Engineers, Japan.

Keywords

• pem
• fem
• elastoplasticity
• anisotropy
• powder compaction