Discrete element study on indentation delamination failure and mechanical properties of thermal barrier coatings with random pore defects

Abstract Indentation damage is a typical failure mode of thermal barrier coatings (TBCs). In this study, A discrete element method (DEM)model of TBCs with random pore defects was developed to study the effects of pore density and pore shape on delamination cracking and mechanical properties under indentation loading. The results indicate that as pore density increases, the length of interfacial delamination cracks decreases, suggesting that pores can impede crack propagation. Accordingly, a pore density factor was defined to quantitatively characterize this negative correlation. Regarding the influence of pore shape on coating damage, Sharp corners are prone to inducing stress concentration, thereby accelerating crack initiation and propagation. With increasing pore density, the indentation modulus and hardness of the coating decrease. The simulation results show good agreement with Mori–Tanaka (M–T) theoretical predictions and existing experimental data. This study provides a theoretical basis for pore control, indentation failure assessment, and life prediction of thermal barrier coatings.