Channel-cracking of thin films with the extended finite element method

The recently developed extended finite element method (XFEM) is applied to compute the steady-state energy release rate of channeling cracks in thin films. The method is demonstrated to be able to model arbitrary singularities by using appropriate enriching functions at selected nodes with a relatively coarse mesh. The dimensionless driving force for channeling cracks is obtained as a function of elastic mismatch, crack spacing, and the thickness ratio between the substrate and the film. The results are compared with those from several previous studies when available. Emphasis is placed on the cases with compliant substrates, for which much less information is available from previous studies. It is found that, while it is quite challenging to model the cases with very compliant substrates using regular finite element method because of the strong singularities, the present approach using XFEM is relatively simple and straightforward.