THE BEHAVIOR OF CRACKS IN ELASTIC-PLASTIC MATERIALS UNDER PLANE NORMAL AND SHEAR LOADINGS

Cracks in structures are often subjected to complex loading conditions. The direction of the crack extension depends on the normal and the shear components of the load. This paper is based on the kinking behaviour of cracks taking elastic-plastic behaviour of materials into account. The J-integral and the mixed-mode components J(I) and J(II) were determined after having performed several finite element analyses for different loading conditions. The path independence of J, J(I) and J(II) is investigated for both, the line integral proposed by Rice and the volume integral proposed by deLorenzi. For correctly determined crack deflection angles the J(II)-component vanishes when a FE-model with a kinked crack is considered. Hence, cracks propagate perpendicularly to the local mode I load.