An analytical model for predicting thermal residual stresses in multilayer coating systems

An analytical model based on force and moment balances was developed to predict the thermal residual stresses in elastic multilayer coating systems due to differential thermal contraction. A closed-form solution was obtained which is independent of the number of coating layers. Specific results were obtained for the distribution of elastic thermal residual stresses within ZrO2/NiCoCrAlY thermal barrier coating systems. Furthermore, the effects of thickness and porosity of ZrO2 ceramic layer on the residual stress and the curvature of coating systems due to cooling process were discussed. It has been found that the curvature almost increased linearly with increasing thickness or decreasing porosity of ceramic layer. Finally, the contribution of bending strain to the thermal stress was examined and the accuracy of approximate solution was estimated.