摘要：A crack will propagate under biaxial loading con-ditions forming wing cracks, where there is a plastic core region at the crack tip. In this paper, mixed mode cracks are divided into two types: tension cracks and compres-sion-shear cracks. A computational method for determin-ing the stress intensity factors at the crack tip is established based on the crack tip elastic stresses. The stress intensity factors under different tensile and compressive loading conditions are computed. The friction effect at the crack surface is considered for the crack initiation and propaga-tion problem of a compression-shear crack. The minimum J2 (second invariant variable of the stress deviation) yield function is used to determine the crack initiation angle of a mixed mode crack. Computed results show that the crack initiation angle is influenced by the crack inclination, load-ing pattern, loading ratio and the friction effect of crack surface.
