Numerical evaluation of stress intensity factors and T-stress for interfacial cracks and cracks terminating at the interface without asymptotic enrichment

In this paper, we extend the recently proposed extended scaled boundary finite element method (xSBFEM)~\cite{natarajansong2013} to study fracture parameters of interfacial cracks and cracks terminating at the interface. The approach is also applied to crack growth along the interface and crack deflecting into the material within the context of linear elastic fracture mechanics. Apart from the stress intensity factors, the T-stress can be computed directly from the definitions, without any requirement of path independent integrals. The method aims at improving the capability of the extended finite element method in treating crack tip singularities of cracks at interfaces. An optimum size of the scaled boundary region is presented for multimaterial junctions. The proposed method: (1) does not require special numerical integration technique; (2) does not require a priori knowledge of the asymptotic fields and (3) the stiffness of the region containing the crack tip is computed directly. The robustness of the proposed approach is demonstrated with a few examples in the context of linear elastic fracture mechanics. A discussion on the crack growth along the interface and crack deflecting into the material is also presented.