A note on the Virtual Crack Closure Technique for a bimaterial interface crack

Abstract

The Virtual Crack Closure Technique was first presented in 1977 for cracks in linear elastic, homogeneous and isotropic material. It makes use of the Irwin crack closure integral to obtain values of the modes I, II and III energy release rates from finite element data. It can easily be extended to anisotropic material. In addition, it was extended to cracks along an interface between two dissimilar linear elastic, homogeneous and isotropic materials. In that case, the energy release rates were seen to depend upon the size of the virtual crack extension usually taken as the size of the element adjacent to the crack tip. Some attempts have been made to remove this dependence. Nevertheless, in most cases, the accuracy of both the energy release rates and stress intensity factors was not consistently good. In this note, the dependence of the energy release rates on the size of the virtual crack extension for interface cracks is analytically accounted for so that the stress intensity factors may be accurately obtained when fine finite element meshes are used, together with a virtual crack extension consisting of more than one element.