Mechanism of Morphology Parameters in Enhancing Thermal Barrier Coatings Life: Non-Gaussian Rough Interface Modeling and Numerical Analysis

The simplified regular interface has a significant difference from the actual morphology, and a part of the extracted actual interface has randomness. The simulation results obtained from the above two interface models are difficult to apply to the improvement of thermal barrier coatings (TBCs) preparation technology. To solve the problem, the exponential autocorrelation function, AR digital filtering technique, Johnson transformation system, and Genetic Algorithm are applied to establish TBCs non-Gaussian rough interface model. The submodel method is applied to carry out multi-scale thermal cycling simulations of the TBCs. Non-Gaussian rough interface stress distribution states are analyzed, and the anomalous damage mechanism in which the TBCs’ life increases with increasing roughness is elucidated. Finally, the effects of roughness, contour slope, root mean square, skewness, and kurtosis on the strength and life of TBCs are analyzed. The results show that the stress extremes at the non-Gaussian rough interfaces of TBCs are affected not only by roughness, but also by kurtosis of non-Gaussian morphology parameters. The anomalous damage mechanism can be explained by the decrease in the non-Gaussian rough interface mean equivalent strain range with increasing roughness. The root mean square slope exhibits a more significant impact on TBCs’ life than roughness. Furthermore, a strategy combining increased roughness with decreased kurtosis offers a viable pathway to surpass current fatigue life limits. The conclusions can guide the improvement of preparation techniques to enhance the service life of TBCs.