Plastic zone boundary and Poisson’s ratio depending on plastic loosening

Abstract

A more accurate determination of the plastic zone boundary for plane strain and plane stress state is proposed. The plastic zone boundary is determined with regard to plastic loosening, given exact stress distribution and Schleicher yield criterion. The presence of mean normal stress in the Schleicher criterion ensures uniform expansion of the plastic zone. The dependence of Poisson’s ratio and constraint ratio for plastic strain on plastic loosening of material is examined. These parameters peak at the tip or in the immediate vicinity of a stress concentrator and decrease with distance from it. In a small neighborhood of the crack tip, a region is found in which Poisson’s ratio is impossible to determine from the Schleicher criterion. The size of this region is identified with the size of the region of exhausted plasticity.