THREE-DIMENSIONAL SIMULATION OF DISLOCATION-CRACK INTERACTIONS IN B.C.C. METALS AT THE MESOSCOPIC SCALE

摘要

A simulation of the dynamics of dislocation loops emitted at or close to a crack tip in b.c.c. metals is presented. The model simulates the growth of the crack tip plastic zone. The elastic (shielding) interactions between the plastic zone and the crack are calculated as a function of time and temperature, allowing modelling of the increase in fracture toughness with temperature (i.e. the brittle-ductile transition near the lower shelf). The three-dimensional nature of the model allows for the first time study of the differences between dislocations of blunting and non-blunting types, i.e. in configurations where the emitted dislocation glide plane either does or does not contain the crack tip.