The Analysis of Stress Concentration at the Dislocation Free Zone Around a Crack Tip

Abstract

With regard to fracture under dynamic load, an interaction model in the form of a fracture model of a crack and a inverse pile-up of dynamic dislocation groups at the tip of a dislocation free zone was proposed. It was analysed based on a coexisting model of static equilibrium and dynamic distribution of dislocation arrays. These analyses showed that the stress concentration at a crack tip is reduced by the shielding effect of dislocation groups and that at the tip of the dislocation free zone is induced by the effective stress distribution in a dislocation array which is a result of the dynamic dislocation distribution. This result shows a theoretical foundation for the experimental result of the existence of a fracture trigger point under dynamic load.