Fracture mechanics of dissimilar materials bonded through an orthotropic interfacial zone

Abstract

In this paper the fracture mechanics of orthotropic materials containing collinear interface cracks is considered. The primary objective is to study the influence of the thickness and the structure of the interfacial regions on the crack driving force. The interfacial region is assumed to be a relatively thin orthotropic elastic layer. The stress intensity factors or the strain energy release rates are assumed to be the main measure of the crack driving force. A relatively simple and efficient method is presented to solve the related elasticity problem. The results are obtained for a wide range of actual material combinations. In order to study the influence of the structure of the interfacial zone, the problem is also solved for isotropic and orthotropic materials bonded through a layer with hypothetically selected material properties. The results show that the effect of the thickness, the mechanical properties and the material orientation of the interfacial zone on the strain energy release rate could be very significant. An interesting and a rather useful result obtained from the collinear crack solutions is that the strain energy release rates for multiple cracks in bonded orthotropic materials with or without an interfacial layer may be predicted by using the results obtained for an isotropic homogeneous plane provided that the normalization factors are selected properly.