An investigation was made of the interactions between a crack and an array of dislocations, in various configurations, using elasticity theory. By treating the crack and dislocations as being singularities in the elastic field of a material, their collective stress and displacement responses near to the crack tip were examined at the micromechanical level. Firstly, a stationary formulation for a crack interacting with a single dislocation was presented, and the effects of the dislocation upon the crack tip field were systematically assessed for various spatial configurations. This stress-displacement analysis showed that the crack remained open at all times for blunting dislocations, while crack-closure was observed at the tip for wake dislocations. The elastic theory of crack and multiple-dislocation interaction was then rigorously studied by considering three types of force exerted on the dislocations along various slip planes. Thus, the slip-forces exerted on a typical dislocation were due to influences arising from the external loading, its own image dislocations, and other interacting dislocations, as well as all their image dislocations. Moreover, the dislocation emission criterion of Lin & Thomson was used, and the behaviour of multiple dislocations was systematically investigated. Finally, the effective stress intensity factor, the shielding of the crack tip from the dislocation array, the geometrical dislocation distribution, and the dislocation-free zone, were explored in detail.

Investigation of the Crack-Dislocation Interaction Effects. J.W.Ju, S.Oh: International Journal of Damage Mechanics, 2008, 17[3], 223-45