Prediction of three-dimensional residual stresses in the multilayer coating-based systems with cylindrical geometry

A numerical model has been developed to predict the thermally induced residual stresses in the multilayer coating-based systems with cylindrical geometry. During the cooling down, the axial forces in the longitudinal direction and the interfacial pressures in the radial direction were generated due to the misfit strains resulting from the differential thermal contraction and could be determined by the continuity conditions at the interfaces. The thermally induced residual stresses in the multilayer coating and the substrate can be predicted based on the solutions to the forces and pressures using layer-by-layer procedure. Specific analyses were made on the residual stresses within the multilayer ZrO2/NiCoCrAlY coatings with graded properties and compositions. Systematic studies were conducted on the effects of the compositional gradient, the thickness, the elastic modulus of the ceramic component of the coating on the residual stresses. Numerical modeling results showed that the residual stress distribution within a graded coating could be adjusted by controlling the compositional gradient. Changing in the coating thickness or in the ceramic component elastic modulus could alter the distribution and magnitude of residual stresses within the coating.