Interaction of periodic arrays of wing cracks

A method for evaluating the interaction of wing cracks in 2-D and 3-D is presented. The method utilizes the assumption that the wing crack can be represented by its extensions and the interaction is solved using a superposition method presented by Kachanov. The method is applied to arrays of parallel initial cracks to determine the critical crack array orientations and assess whether the coalescence of closely-spaced small cracks causing a shear-like failure observed in 2-D is possible in 3-D. The results show that the shear failure can be achieved also in 3-D, but not with such an instability as in 2-D.