Vertical Stress State Analysis and Fatigue Life Prediction of Thermal Barrier Coating Considering TGO with Nonuniform Thickness

Thermal growth oxide (TGO) is produced when a thermal barrier coating (TBC) works, and the generated TGO is nonuniform at the peak and valley of the TBC interface. The aim of this paper is to clarify whether the nonuniform TGO thickness model is better than the uniform thickness model in TBC simulation. First, finite element models of TGO with nonuniform and uniform thickness are established based on the TBC tube experiments. Then, the vertical stress perpendicular to the TC interface morphology and the corresponding shear stress are analyzed based on the stress transformation equations. Finally, the fatigue life of the TBC is analyzed by nonuniform and uniform TGO thickness models. The results show that the area of the local maximum of the vertical stress and the shear stress for different TGO thicknesses is 4-10 µm from the TC interface morphology peak, which can be considered the risk area for fatigue failure of the TC interface. The risk area in the uniform TGO thickness model is consistent with that of the nonuniform thickness model. The fatigue life prediction error of the TBC using the nonuniform TGO thickness model is 29.53%, which is smaller than that of the uniform thickness model, proving the need to consider the nonuniform thickness of the TGO in TBC simulations. The fatigue life prediction result is verified by different TBC experiments. The conclusions of this study can provide guidance for TBC simulation analysis in the future.