304 離散転位法による疲労き裂屈曲挙動の解析

概要

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The discrete dislocation (DD) method is one of mesoscopic scale computer simulation procedures which can deal with both the crack and dislocations. In this paper, each dislocation movements and stress field near a fatigue crack tip under mixed mode condition, Mode I and II, were investigated by means of the 2-dimensional DD analysis. The material analyzed was an iron with bcc structure which has two preferred slip direction, and the fatigue crack was assumed to progress along one of two slips. The quantity of the crack plane deformation along the crack growth direction was found to become smaller as crack growth due to the constraint of slip deformation by grain boundary, and then to be exceeded one along the other slip plane direction. The crack kinking behavior which has been observed experimentally can be well simulated by using the model that the crack kinks when this excess occurs.