Inclusion of microscopic rotation of powder particles during compaction in finite element method using Cosserat continuum theory

The e¤ect of microscopic rotation of powder particles in compaction is included in the rigid-plastic Þnite element method on the basis of the Cosserat continuum theory. In the Cosserat continuum theory, couple stress induced from the microscopic rotation is introduced, and the equilibrium equations of moment for the couple stress are solved simultaneously with those of force. A yield criterion for the Cosserat porous continuum is proposed by taking the e¤ect of the couple stress into consideration, and constitutive equations for the rigid-plastic porous material are derived from the yield criterion on the basis of the associated ßow rule. The equilibrium equations of force and moment for the Cosserat continuum are formulated by the use of the Galerkin method. The e¤ect of microscopic rotation of powder particles in plane-strain closed-die compaction is examined. In addition, the calculated result is compared with that for the conventional continuum without the microscopic rotation