Stress intensity formulas for three-dimensional cracks in homogeneous and bonded dissimilar materials

This paper is concerned with maximum stress intensity factors of arbitrary shaped defects or cracks under mixed mode loading and also cracks terminating at an interface. A convenient formula is proposed in terms of parameter, where “area” is the projected area of the defects or cracks. First, a rectangular crack under mixed mode loading is considered with varying the aspect ratio and compared with the results of elliptical cracks. Then, parameter is found to be useful under mixed mode loading. Second, a rectangular crack, which is perpendicular to and terminating at a bimaterial interface, is investigated with varying the combinations of materials constants. At the crack front the maximum stress intensity factors are expressed as a function of the elastic ratio of the materials. On the other hand, the generalized stress intensity factors at the interface are expressed as a function of Dundurs parameters α and β. Proposed formulas are usefully evaluating defects with any aspect ratio under any combinations of the materials.