摘要
The dislocation-free zone model of mode-Ill fracture using the discrete dislocation model is investigated. It is found that the stress intensity factor K D for dislocation emission is dependent on the crack length and the dislocations in the system but is not a materials constant as reported in the literature. On the basis of this argument, we can explain the mechanical properties of materials, such as toughness and the ductile-to-brittle transition temperature. When the crack length is shorter than the critical value, no equilibrium dislocation exists in the finite space. In addition, we also found that the crack length increases with a decrease in the size of the dislocation-free zone. Finally, a comparison between the discrete and continuous dislocation approaches is made. © 1990 Taylor & Francis Group, LLC.