Finite Element Simulation of Stress Distribution in Plasma Sprayed Thermal Barrier Coating

A simulated micrograph of thermal barrier coating (TBC) was chosen to study the stress distribution at the thermal loading, cooling from initial temperature to room temperature, by using the thermoelasticity finite element method. The influence of thermally grown oxide (TGO) and its thickness on the stress distribution in TBC were analyzed. The simulated result was compared with the experimental result reported in literature. The results show that tensile stress was present at the peak and compressive stress was present at the valleys in as-sprayed conditions (that is, without TGO). When growing TGO layer, tensile stress appeard at the valley and compressive stresses appeared at the peak. The stress inversion appeared in the topcoat after reaching a certain TGO thickness, and the stress inversion was delayed by the increase of interface roughness. The predicted values of stress agreed well with the experimental result reported in the literatures, which confirms the validity of the simulation.