The behavior of screw dislocations which were dynamically emitted from the tip of a surface crack during loading and unloading was investigated by using a discrete dislocation model. The critical stress intensity factor at the crack tip, for dislocation emission, was a function of the friction stress, core radius of the dislocation and number of dislocations near to the crack tip. During motion, the velocity of dislocations was assumed to be proportional to the effective shear stress; raised to the third power. The effect of crack length and friction stress upon the dislocation distribution, elastic zone, and dislocation-free zone during loading and unloading was predicted.

The Behavior of Screw Dislocations Dynamically Emitted from the Tip of a Surface Crack during Loading and Unloading. C.C.Huang, C.C.Yu, S.Lee: Journal of Materials Research, 1995, 10[1], 183-9