Semi-analytical investigation of stress interfacial effects in ductile media with nanosized spheroidal cavities

摘要

In this paper we investigate the interfacial stress effects on the macroscopic yield strength of plastic porous media containing nanosized spheroidal cavities. The solid matrix is assumed to obey the von Mises criterion with associated flow rule. Analysis of a rigid-ideal plastic spheroidal unit cell, containing a confocal spheroidal cavity, and subjected to arbitrary mechanical loadings is made. Void size effects are captured by considering at the interface between the matrix and the cavity a surface stress model, which relates the jump of the traction vector to the interfacial residual stress and to interfacial plastic strain. The resulting macroscopic criterion for the nanoporous material exhibits unusual features such as (i) an increase of the yield stress when the void size is decreased, (ii) asymmetry between the yield stress in uniaxial tension and compression.