The effect of TGO growth on the crack propagation within TBCs by the material configurational forces

The present study focuses on clarifying the impact of continuous formation of thermally grown oxide (TGO) on the shielding/anti-shielding and deflection of surface cracks within the TC. The growth stress in the TC due to the expansion of TGO layer is taken into account by introducing a new three-layered model in TBCs where the initial residual stress in TC is also presented. The theory of material configurational force is innovatively used to analyze the influence of the growth of TGO layer on the crack-tip driving force, i.e., the Jk-integral. A fracture criterion is employed to predict the deflection of lengthways propagation of the surface crack via the maximum energy release rate associated with Jk-integral. The influences of the key factors such as the initial crack length, the initial crack inclination angle, the magnitude of growth eigenstrain of TGO, the dwelling time of TGO at elevated temperature on the propagation of surface cracks are analyzed.