Identification of Yield Surface for FEM Analysis of Powder Die Compaction

Abstract

Single shear test for powder compact has been suggested to identify shear failure envelope on several powder. Critical state line of power has been estimated directly since dilatancy characteristics can be observed in stress pass on single shear. Uniaxial compaction failure test of powder compact is also conducted to measure shear failure characteristics in lower stress state. It is recognized that variation of cohesion value of powder compacts has clearly depended on compaction pressure. Determination of subsequent yield surface is able to accomplish to identify internal friction angle and cohesion with several green compact density. Results of FEM (Finite Element Method) analysis of powder die compaction with Drucker-Prager CAP model simulates almost proper density distributions of green compact and occurrence of shear stress concentrations in ejection stage. It is concluded that estimation of critical state line using single shear test method becomes useful way to identify shear failure and subsequent yield surface.