A thermal mechanical coupled damage accumulation model for rare earth-doped EB-PVD TBCs under isothermal oxidation, cyclic oxidation and creep conditions

Abstract

Thermal barrier coatings (TBCs), a key thermal protection technology, can effectively improve the service temperature and life of aircraft engineturbine blades. It is crucial to accurately predict the damage and life of TBCs under service environments for ensuring the safe and stable operation of engines. In this work, the isothermal oxidation, cyclic oxidation and creep tests of EB-PVD TBCs were carried out at 980 °C. The microstructure evolution of the TBCs was observed to reveal the failure mechanism of TBCs. The vertical compressive strain and compressive stress of TBCs were determined to characterize TBCs damage based on room-temperature compression tests and three-dimensional digital image correlation technology. In addition, a nonlinear coupled damage accumulation model of TBCs was developed, considering high-temperature oxidation, cyclic oxidation and creep conditions at 980 °C. Results show that the TBCs damage during service can be attributed to factors including the thermally grown oxide (TGO) growth, thermal mismatch stress and plastic deformation accumulation. The error between predicted damage and experimental results is <15 %.