Discussion on Criteria for Crack Initiation in the Immediate Vicinity of the Sharp Edges of Dispersed Inclusions

Abstract

The crack initiation in the immediate vicinity of the sharp edges of dispers ed inclusions plays an important role in the strength of dispersion composite materials. The purpose of this work is to duscuss the criteria for crack initia tion in the immediate vicinity of the sharp edges, i.e. the maximum hoop stress criterion, the minimum strain-energy density criterion and the max imum principal stress criterion. These criteria are based on the strength of stress singularity at the sharp edges of inclusions. Experiments are performed by using epoxy resin specimens containing a flat steel inclusion. From the ex perimental results, it is found that the maximum principal stress criterion proposed by the authors is the best one for crack initiation in the immediate vicinity of the sharp edges of dispersed inclusions.