Mixed-mode fracture criteria for the materials with different yield strengths in tension and compression

Abstract

The Nadai elastic-plastic boundary is introduced to define the core region, instead of a core region with a constant distance r from the crack tip and a core region with the Mises elastic-plastic boundary. Taking into account fracture parameters along the Nadai elastic-plastic boundary, two improved fracture criteria are presented for the two commonly used fracture criteria, the maximum tangential-stress criterion and the minimum strain-energy-density criterion. Using the two improved fracture criteria, the effect of properties of the material with different yield strengths in tension and compression on the mixed-mode crack fracture can be revealed. It is shown by analysis that the fracture of the mixed-mode crack is affected by this kind of property of the material. Many results are given by using the two improved fracture criteria, and they are compared with those obtained by using the commonly used mixed-mode fracture criteria.