PARAMETRIC STUDIES OF FAILURE MECHANISMS IN THERMAL BARRIER COATINGS DURING THERMAL CYCLING USING FEM

摘要

Thermal barrier coatings (TBCs) are widely used on different hot components of gas turbine engines such as blades and vanes. Although, several mechanisms for the failure of the TBCs have been suggested, it is largely accepted that the durability of these coatings is primarily determined by the residual stresses that are developed during the thermal cycling. In the present study, the residual stress build-up in an electron beam physical vapour deposition (EB-PVD) based TBCs on a coupon during thermal cycling has been studied by varying three parameters such as the cooling rate, TBC thickness and substrate thickness. A two-dimensional thermo-mechanical generalized plane strain finite element simulations have been performed for thousand cycles. It was observed that these variations change the stress profile significantly and the stress severity factor increases nonlinearly. Overall, the predictions of the model agree with reported experimental results and help in predicting the failure mechanisms.