Fracture analysis of thermal barrier coating structure with interfacial crack under steady-state thermal loading

Considering unilateral interfacial crack in thermal barrier coating(TBC),virtual crack closure technique(VCCT) was used to calculate strain energy release rate of the structure under thermal loading,and unilateral interfacial crack propagation behavior was studied according to the results.During calculation,the stable temperature field was obtained by the given temperature boundary conditions,and taken as the thermal loading in the structure.The temperature-dependent material parameters were adopted.The results show that,in the given conditions,the total energy release rate is greater than interfacial fracture toughness during crack initiation stage,indicating that once the unilateral interfacial crack appears,the unstable propagation will occur subsequently under thermal loading.When the crack extends close to the free end,the total energy release rate decreases rapidly and drops below the interface fracture toughness,leading to stop of crack propagation.The analysis shows that,for the structure of TBC with unilateral interface crack under high thermal loading,the ceramic coat won't flake-off completely.