Crack Tip Fields with Strain Gradient Effects

Abstract

In this paper, a kind of strain gradient theory proposed by Chen and Wang (2001) is briefly introduced and is used to analyze the crack tip field in homogeneous materials and interface crack tip field with the help of finite element methods. Differences are found between the two kinds of crack tip fields. For the crack tip field in homogeneous materials, the whole field consists of a strain gradient dominance zone, a classical plasticity field and a K field. While for the interface crack tip field, there are only the strain gradient dominance zone and a K field and the classical plasticity field hardly exists. The reason will be given in the present paper. For both kinds of crack tip fields, the effective stresses near the crack tip are much higher than the counterparts in the classical field, which provides an explanation to the experimental observation of cleavage fracture in ductile materials (Elssner et al., 1994).