Fracture analysis of thin films on compliant substrates: A numerical study using the phase field approach of fracture

In this work, the phase field (PF) approach for brittle fracture in the bulk coupled with the cohesive zone model (CZM) for pre-existing interfaces is exploited for the simulation of fracture of thin films on compliant substrates, which are structural configurations of extensive use in many engineering systems such as protecting layers for vessels, stretchable electronic devices, among many others. Due to the coupling between the two aforementioned models for fracture, the proposed approach enables capturing bulk damage and crack deflection or penetration at the prescribed interfaces in a robust and reliable manner, these scenarios depending on the particular mechanical properties of the system via a sensitivity analysis. In this concern, it is shown that the proposed approach is capable of predicting several complex crack paths for different fracture modes, concerning the 2D and 3D thin film fracture problems herein investigated: (i) deflection/delamination, (ii) penetration and (iii) deflection/delamination at the prescribed interface in combination with penetration. Moreover, the effect of the interface fracture energy on the predicted crack path has been carefully investigated.