Dynamic Yield Loci of A Porous Visco-plastic Material by Using A lower Bound Approach

Abstract

Based on the study of a representative volume element (RVE) of porous viscoplastic material, a void growth model is proposed in this paper. The constitutive relation of the matrix material is in the over stress form given by previous authors. A lower bound approach by constructing a statically admissible stress field in the RVE is employed, and the corresponding dynamic yield loci of this porous material are obtained. The dynamic yield loci derived from both the lower bound approach in the present paper and the upper bound approach in Ref. [5] are compared for different values of porosity f and strain rate parameter m. They are rather close.