Mesoscale energy dissipation prediction in thermal barrier ceramic coatings under nonlinear vibration

The focus of this study is on the development of a fundamental understanding of the unique microstructural features and mechanisms responsible for the amplitude-dependent and energy dissipation in thermal barrier ceramic coatings (TBCs) under nonlinear vibration. Such understanding will ultimately guide the fabrication of TBCs with higher levels of energy dissipation for mitigating high cycle fatigue damage in turbine engines. This is achieved through the employment of a thermodynamic-based nonlinear cohesive laws that consider interfacial degradation, debonding, plastic sliding, and Coulomb/contact friction between the interfaces of microstructural recursive faults in the ceramic coating microstructure. Through the conducted representative volume element (RVE) simulations, it is concluded that the major part of energy dissipation is achieved through contact friction which results from sliding of the splat, the main building blocks of plasma sprayed TBCs, interfaces along the microstructural recursive faults. Energy dissipation due to progressive decohesion and evolution of new microcracks is not that significant as compared to energy dissipated due to increased friction from existing and new created faults. Therefore, internal friction is the main mechanism that makes TBCs effective dampers.