MODELING THE PLASTIC ZONE AHEAD OF A CRACK BY TWO DIMENSIONAL DISCRETE DISLOCATION DYNAMICS

We present a detailed analysis of the kinetic of the formation of a plastic zone ahead of a crack tip, modeled by discrete dislocation dynamics (in two dimensions). The effect of crack tip emission is emphasized by comparing the average shielding (local stress intensity factor) and the microstructure obtained with and without a dislocation source aligned with the crack tip. The results are averaged over multiple runs in order to obtain significant differences which overcome the dependence on source distribution. It is found that crack tip emission creates a pile up which major role is to shield more efficiently the tip. We conclude on the necessity to consider emission from the tip when simulating ductile solids like fcc crystals.