Estimation of stress distribution developed in powder bed during compaction by FEM considering anisotropic parameters

Stress analysis in the compaction of ceramic powder was: performed by Finit e Element Method (FEM) to predict the optimum conditions. In order to apply to practical problem, the powder bed was treated as elasto-plastic materia l, and the constitutive equation was derived from Drucker-prager's yield fu nction expressed in terms of invariants of stress tensors and Hill's anisot ropic parameters on stress in the powder bed. The powder bed has multiform bulk density distribution, along with behavior of discontinuous deformation during compression whereby, the mechanical characteristics of the powder h ed change during compaction. Thus, it is necessary that the powder characte ristics are treated as a variant associate with the progress of powder comp action. In this paper, Young's modulus and strain-hardening rate are expressed as a function of minor principal stress and strain. These function can be deter mined from a triaxial compression test. Hill's anisotropy parameters induce d at compaction process were numerically obtained by simulation of the comp acting behavior of particles which was performed by Particle Element Method (PEM). On the basis of the proposed constitutive model, the problem of powder comp action is analyzed. The calculated results of the nonlinear stress-strain r elation, stress distribution during powder compaction agree well with the m easured ones. It is shown that the procedure proposed here offer the useful information to decide the optimun conditions of powder compaction.