Thermo-mechanical coupling analysis of thermal barrier coatings with cooling holes

Abstract

The cooling holes on gas turbine blades act as stress concentration regions, which become the starting points for cracks in thermal barrier coatings (TBCs) during applying the cyclic mechanical and thermal stresses. To evaluate the damage behavior of the cooling holes in TBC system, a three-dimensional finite element model possessing a cooling hole was established. The inelastic constitutive equation developed by our research group for the TBC’s top layer (TC) was employed to calculate the damage in TC layer. The effects of displacement load, thermal load, and their phase differences were investigated. The simulation results indicated that damage was concentrated on the TC layer around the cooling hole due to stress concentration. Furthermore, out-of-phase loading resulted in significantly higher damage to the TC layer compared to in-phase loading. Additionally, as the displacement load increased, the location of maximum damage shifted from near the TC/substrate interface to the surface of the TC layer. Moreover, the region of damage concentration around the cooling hole varied as the displacement load increased. This study provides new insights into the damage behavior of cooling holes under the interaction of mechanical and thermal stresses, facilitating the service life evaluation and working condition optimization of the gas turbine.