Elastic interaction of a wedge crack with a screw dislocation

Plastic deformation occurring at a crack tip can alter the stress field in the vicinity of the crack tip when edge dislocations are generated on inclined planes, thus creating a wedge-shaped blunted crack. The propagation of blunted cracks has been observed by Vehoff and Neumann during in situ SEM observations of fracture cracks in copper and silicon and also during in situ TEM tensile deformation of niobium. In spite of the significant role that crack blunting can play in the fracture mechanics of elastic-plastic crack propagation, very little work has been reported on the elastic properties of the blunted cracks. In the present work, the stress field near the tip of a semi-infinite wedge crack under mode III loading conditions has been obtained by the method of conformal mapping. An expression is found for the stress components in front of a wedge crack of angle α