Numerical and Experimental Investigation of Residual Stress in Thermal Barrier Coatings During APS Process

Thermal barrier coating (TBC) system is widely used in modern gas turbines to protect the internals and enable them to service in higher temperature environment. Residual stress in the TBC system can be induced during its production procedure, such as air plasma spraying (APS) process, and affect its performance to a large extent. The temperature history and the evolution of residual stress in the TBC system during APS process were studied in this paper by finite element simulation and hole-drilling experiment. A five-layered TBC specimen model was established, and a thermo-mechanical-coupled analysis was conducted in the simulation. The modified element birth-death technique was used to represent the formation of TBC. In addition, experimental validation of the simulation result was carried out on a TBC specimen using hole-drilling technique combined with moir, interferometry. The experimental data agreed well with the simulation results and the study of this paper could provide a reference for the production of the TBC system.