Thin film adhesion measurement by nanoindentation: Review of methodologies and validation by means of finite element simulations

In this paper, a review of existing methods to determine the energy release rate (ERR or G) from indentation results is presented and compared to the finite element simulations. Due to the complexity of the indentation process - high deformation, plasticity, geometric non-linearity, crack propagation at the interface and/or bulk material, phase transition etc. - the accuracy and validation of the FE-model with the analytical approaches reported in the literature [2], [7], [9] [etc.] is important. In this work, axial symmetric models were used to extract the crack driving forces during the indentation process. Simulations have been performed with ABAQUSTM [4]. The crack propagation analysis was done by means of the cohesive zone approach for interfaces in general as well as the virtual crack closure technique for brittle interfaces It was observed that the static evaluation of the ERR for initially specified interfacial delaminations (crack existing before indentation) will lead to lower ERR values as compared to the transient calculations taking into account the crack propagation (Fig. 2). Finally, a modification to the analytical approach as reported by [2] is presented to match the simulated ERR accurately.