Analysis of the partially closed interface crack in orthotropic materials

The determination of fracture parameters such as mode I and II stress intensity factors, K_I and K_II, is of considerable practical importance in the analysis and failure prediction of various types of structures. For example, interfacial cracks may develop and propagate in bonded joints or lead to delaminations in composite materials. The finite element method is a powerful technique for analyzing complex structures; however, the singular behavior near crack tips is poorly approximated by conventional finite elements and convergence theorems cease to be applicable at those locations. In a previous paper, a combined analytical and numerical model based on frictionless crack face contact was used to obtain fracture parameters at interfacial cracks in composite laminates in cylindrical bending and subject to transverse loads. In this article, we further consider the method and extend the previous results by considering a variety of shear and normal loads on a cracked bimaterial plate with isotropic or orthotropic materials. Furthermore, additional validation of the method is provided by comparing the results with closed form solutions in the literature for the special case of isotropic materials in a combined tensile and shear field, and good agreement is found. Overall, we conclude that the method provides a practical way to analyze a variety of engineering structures with interfacial cracks.