Dislocation-crack edge interaction in dynamic brittle fracture and crack propagation

Abstract

Due to the formation of small inelastic zones near crack edges, brittle fracture and crack propagation involve dislocation-crack edge interaction. An approximate transient solution for a single screw dislocation moving near a propagating Mode III crack is obtained here, and used to study dislocation arrays which exist prior to fracture in circular zones around the crack edge. Using dislocation force concepts, it is found that these dislocations coalesce into bands near the crack surface when fracture is triggered by SH-wave diffraction and, if their speeds exceed that of the crack edge, collapse onto the crack surface itself. Moreover, this dislocation motion has a noticeable if brief effect on the dynamic stress intensity factor.