Numerical study of thermomechanical delamination mechanisms in segmented high-temperature coatings

Abstract

This work addresses the thermomechanical delamination mechanisms in segmented multilayered high-temperature coatings system using computational fracture mechanics approach. A representative unit cell model is presented, where the thermomechanical load is generated by combining uniform temperature changes and boundary-loaded displacements. The model is used to analyze coatings over a broad range of material properties, geometries, and loads. The findings suggest that, for a given coatings system, the mechanical load carried by the top-coat layer is the only force that drives delamination developing along the top-coat/bond-coat interface. The introduced multiple vertical cracks lead to stiffness release over a limited region, resulting in reductions in stress and delamination driving forces within that region. An empirical equation is established using multiple regression analyses to evaluate the delamination driving forces. Accordingly, the importance of the influential factors on the delamination is ranked, and design maps are constructed to facilitate the development of durable coatings.