Crack and dislocation propagation in an idealized crystal model

Abstract

Results are presented of computer simulation studies of crack dynamics in an idealized two-dimensional crystal model. It is based on a model introduced by Sanders which permitted crack extension and has been modified here to permit dislocation generation and propagation as well. The studies indicate that, depending on the parameter values, the model exhibits either brittle or ductile behavior. In the former case it is found that, except at very high stress levels, the crack reaches a steady subsonic terminal velocity whose value is stress dependent. Supersonic crack velocities are observed at very high stress levels in accord with the theoretical prediction of Sanders. The effect of temperature on crack speed is found to be small. For the parameters which lead to ductile behavior, the crack does not extend but is blunted by dislocation generation from its tip.