Finite Element Implementation of a Thermal Barrier Coating Life Model on a Gas Turbine Blade

Abstract

Thermal barrier coatings (TBCs) play a vital role in gas turbines, protecting critical hot-section components from extreme combustion gas temperatures. These coating systems act as a thermal insulation barrier, reducing the temperature of the load-carrying metallic substrate. Loss of this protective layer, through so-called spallation, exposes the base metal to higher temperatures and accelerates its degradation. Predicting TBC spallation life has therefore been a research focus for decades. Nevertheless, industrial-level implementable models remain scarce, largely due to the implementation complexity of existing models. In the current work, a TBC life model is implemented within a finite element (FE) framework to enable practical use in industrial settings. The life model follows a power law relation and utilises the energy release rate as the main damage-driving parameter. The implemented model stands out through its practical applicability by expressing the damage-driving parameter using strain energy density and substrate surface strain invariants extracted from the FE analysis. Common damage mechanisms, including oxidation, sintering, thermomechanical fatigue, and sudden rupture, are accounted for. The methodology is applied to a TBC-coated first-stage turbine blade. The TBC life model is able to capture the common TBC spallation area on gas turbine blades.