Analysis of the crack penetration/deflection at the interfaces in the intelligent coating system utilizing virtual crack closure technique

The two-phase model and three-phase model were established and used to study the behaviors of crack penetration/deflection at the interfaces in the crack-detected intelligent coating system based on the energy criterion. The effect of the putative initial length of the crack deflection and penetration, the elastic mismatch parameters and the thickness of the interface layer on the ratio of energy release rates for the deflected and penetrated crack was calculated by the virtual crack closure technique. The numerical results can interpret the behavior of substrate crack penetration observed on TC21 titanium alloy monitored with the crack-detected intelligent coating and can be used for the optimization design of the coating system.