Failure analysis and life prediction of thermal barrier coatings on turbine blades under localized cyclic thermal loading

Thermal barrier coatings (TBCs) have been widely used in gas turbines and aero-engines because of their excellent thermal insulation properties. However, the mechanical properties and variability of working conditions lead to varying service lives. In this study, failure probability and fatigue lifetime of TBCs on turbine blades under local thermal cycles were carried out based on stress-strength theory and the Monte Carlo method. Firstly, a three-dimensional model of the blade coating was created using CATIA and ABAQUS software. The distribution of temperature and stress within the TBCs was analyzed using finite element simulation. Next, according to the stress-strength theory, the failure probability of TBCs was calculated from the relationships between stress, strain, and thermal shock time. The influence of three principal factors (airflow temperature, heat source radius, and heating angle) was analyzed and compared with the probability obtained by the method based on critical strain energy rate. Finally, image processing technology was integrated to predict the service time of TBCs. The results indicated that the failure probability calculated by the stress-strength method aligns more closely with the experimental data, with a maximum deviation of 20.0 %.