Simulation of the Effect of Sub-Micron Interface Roughness on the Stress Distribution in Functionally Graded Thermal Barrier Coatings

In this research, a numerical modeling method was utilized to calculate the stresses occurring during the thermal cycling in a functionally graded thermal barrier coating (fg - tbc). the temperature – dependent material response of this protective material was taken into account and the effects of the thermal cycle and interface morphology of the ceramic /metallic layer in a functionally graded coating system was investigated. sinusoidal mode of asperity with specific wavelength and amplitude was used to model the two dimensional geometry of interface profile between layers. a finite element model was used to model the effect of the thermal loading imposed on the thermo-mechanical response and stress distribution. in this regard, different observable facts were taken into account in the model such as: non- homogenous temperature distribution, periodic boundary condition and convective heat transfer. these phenomena depict the most real world situation in numerical simulation of multi- layer coating during cooling and thermal cycling, specifically near the ceramic/metal interface. in addition, regions which are potent to crack initiation and propagation in the system and the subsequent delamination places of the tbcs system were predicted.