Simulation Analysis of Stress Distribution of Gradient Composite Coatings under the Application of Fluid-solid-thermal Coupling

Previous simulation methods for composite coatings are mostly based on the influence of one single physical field, which cannot reflect the real mechanical properties under actual working conditions such as multi-physics coupling. According to the typical working conditions of aero-engine accessories, a mathematical model describing the fluid-solid-thermal coupling phenomenon for gradient composite coatings is established, and the distribution of von Mises stress inside the coatings for different changing ways of compositions is calculated. It is shown that the three transition ways cast different results of thermal strain and von Mises stress in the coatings. Take the spline used in the aero-engine accessories as an example, the thermal stress is much larger than the stress caused by load-lubrication coupling under the application of the actual load and temperature conditions. With the action of the coupling effects of load-thermo-lubrication, the maximum stress locates at the surface layer and the stress spreads to the substrate with the increase of composition gradient. The transition way with increasing gradient can obtain the smallest "max von Mises stress" in the coatings. Within the temperature range of interest, the "max von Mises stress" reduces 14.5% by comparison with that for the decreasing gradient method. The simulation methods established can simulate the actual working conditions more closely. The research results can be used to guide the design and preparation of gradient composite coating.