Effect of cohesive behaviour and residual stress on the indentation response of elastoplastic film/substrate structure

In this study, the effects of cohesive behaviour and residual stress on the indentation response of an elastoplastic film/substrate structure were explored. A finite element model was developed by highlighting the contact between the Berkovich rigid indenter and the film/substrate model. The behaviour of the film is defined as the power-law constitutive properties, the substrate is assumed to be perfectly elastic, and the cohesive zone model is employed to evaluate the film/substrate interface interaction. By emphasizing the cohesive behaviour, delamination between the film and the substrate is investigated as an influential factor in the damage of layered device. In addition, the residual stresses generated during the thin film preparation are considered in the finite element model. Predictions of parameters such as Young's modulus, yield strength and hardening exponent were made based upon the curves derived from the finite element analysis. A dimensionless function is derived from the finite element simulation and an algorithm is proposed to reversely solve the intrinsic parameters and residual stresses of the elastoplastic material from the indentation response.