Characterizing the Failure Mechanisms of Spallation in Thermal Barrier Coatings with Cooling Holes

The application of thermal barrier coatings (TBCs) with integrated cooling holes in the design of turbine blades and combustion liners has become a prevalent approach in the aerospace industry. However, the occurrence of cracks and spallation failures emanating from the hole edges leads to a decrease in the operational lifespan of these components. This study endeavors to evaluate this issue by proposing an energetic mechanical model, which takes into account the free edge effect around the cooling holes. The critical mechanical conditions responsible for the delamination and spallation at the hole edges are determined through a systematic examination of the characteristic distance for stress evolution, non-uniform temperature fields, hole radius, and through-thickness variable material properties. The results confirmed the accuracy of the new mechanical model and demonstrated its potential to improve the operational lifespan of turbine blades and combustion liners. The proposed analytically mechanical model offers a more comprehensive and accurate understanding of the interfacial delamination failure coatings with cooling holes, which can be used to optimize the design and material selection for enhanced performance and reliability.