Finite element simulation of thermal barrier coating performance under thermal cycling

In this paper, a numerical simulation of stress development within the air plasma-sprayed thermal barrier coating system incorporating nonlinear behavior under compression for the top coat ceramic layer is presented. The nonlinear behavior as well as its evolution with sintering at high temperature is simulated using a microstructure based model. The simulation results indicate that this nonlinearity has a significant role on distribution of the residual stresses in this layer resulting from the thermal cycling. A parametric study is carried out to investigate the effects of the microstructural features of the top coat ceramic layer on residual stress distribution. It is revealed from the simulation results that the variation of porosity has only a negligible effect on the residual stress distribution. In addition, the stresses accountable for the crack growth can be lowered by changing the microcrack densities of the top coat layer within a specified range.