Numerical simulation of damage and inelastic deformation of porous thermal barrier coatings system

Abstract

Thermal barrier coating (TBC) is widely applied to gas turbine blade surface to protect the metallic substrate from high-temperature combustion gas flow. Porous TBC system has been developed by our research group in order to further increase the turbine inlet temperature. In this study, in order to appropriately evaluate the stress distribution and the crack growth behavior in porous TBC subjected to a monotonical tensile loading at high-temperature, a finite element analysis model with pores in top coat (TC) based on an actual cross-sectional image of TBC specimen was established. The inelastic constitutive equation of TC and the crack growth algorithm proposed by our research group were also introduced into the analysis model. It was confirmed that the stress distribution and the crack growth behavior obtained by the analysis under a monotonical tensile loading condition were consistent with the experimental results under 293K and 1273K temperature conditions. In addition, the analysis results from three models with different porosity showed that the crack initiation strain is increased with increasing the porosity. The increase of porosity could improve the apparent ductility of TC. It was considered that the improved ductility suppressed the cracks initiation.

Keywords

• gas turbine
• thermal barrier coatings
• finite element analysis
• porosity
• crack