Minimum life point determination and fatigue life prediction of thermal barrier coatings based on extended stress and strain method

Abstract

The study develops the extended stress and strain method (ESSM) capable of extracting the stress-strain perpendicular to the 3D thermal barrier coatings (TBCs) interface and shear stress-strain along the interface. Then, the stresses perpendicular to the interface and the shear stresses along the interface are analyzed in comparison with the conventional stresses. Finally, fatigue life prediction of TBCs is carried out based on the ESSM. The results show that, the cycle maximum value locations of shear stress along the interface are located at 5.1 μm along the circumferential direction to the peak. The previous experimental study of TBCs proves that it is reasonable to use the shear stress to determine the location of the minimum life point, and the minimum life point location is the cycle maximum value location of the shear stress. The maximum error in fatigue life prediction of TBCs using the ESSM 45.6 %, which is 20.5 % less than that using equivalent strain. The ESSM can directly determine the location of minimum life point and improve the fatigue life prediction accuracy of TBCs, which has great potential in damage analysis and fatigue life prediction.