Simulation of damage and failure processes of thermal barrier coatings subjected to a uniaxial tensile load

The tensile bond strength of thermal barrier coatings (TBCs) is an important criterion in evaluating the quality of coatings, which depends significantly on the coatings' complex microstructures. In the current study, a three-dimensional (3D) microscopic structural model reflecting the actual interface morphology and pore distribution of TBCs is built using microcomputer tomography (micro-CT). The model is then applied to investigate the 3D spatial evolution processes of damage and failure under uniaxial tension using FE techniques. To validate the numerical simulation results, the tensile responses of the TBCs are measured and a follow-up quantitative description of the tensile fracture morphology is obtained with a 3D surface profiler. The simulation results are in good agreement with the experimental data. Our simulation results show that the local stress concentration induces two types of crack sources located either at the top coat (TC)/bond coat (BC) interface or along the pore boundaries; as the load increases, only the microcracks at the interface amalgamate and begin to form a primary crack; then the primary crack propagates rapidly horizontally along the interface, eventually inducing an undulating fracture morphology.