Elastic interaction of a wedge crack with a screw dislocation

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Abstract
The elastic field of a semi-infinite wedge crack and its interaction with a screw dislocation under mode III loading conditions are examined. The stress field around the wedge crack is expressed in terms of a wedge stress intensity factor. The rate of falloff of the stress field with distance from the crack tip is found to be a function of the wedge angle. The relationship between the stress intensity factors for the wedge and sharp cracks is derived and used to estimate the magnitude of stress relaxation occurring at the crack tip due to crack blunting. The crack extension force for the wedge crack is calculated and is shown to be zero. The modifications in the stress field and the local wedge stress intensity factor due to the presence of the dislocation are calculated. From the image stress on the dislocation, the condition for the emission of dislocations from the wedge crack is obtained in terms of the critical wedge stress intensity factor for dislocation generation. It is found that the emission of dislocations from the crack tip is more difficult when the crack is blunting.