The crack velocity, and the velocity of each dislocation, were assumed to be proportional to the third power of the stress intensity factor and to the effective stress, respectively. The stress intensity factor for the emission of the nth dislocation was derived on the basis of the spontaneous emission criterion. It was found that the stress intensity factor for dislocation emission was independent of the crack mobility, while the number of dislocations which was emitted decreased with increasing crack mobility. The number of emitted dislocations, and the size of the plastic zone, decreased while the maximum stress intensity factor for dislocation emission increased with increasing initial crack length. The size of the dislocation-free zone increased with increasing initial crack length in the steady state. The dislocation-crack system attained a steady state when the dislocations and crack tip moved at the same velocity.

Dynamic Emission of Screw Dislocations from a Propagating Crack Tip. Y.Z.Tsai, S.Lee: Journal of Applied Physics, 1997, 81[5], 2089-93