Mechanical and thermomechanical mesoscale analysis of multiple surface cracks in ceramic coatings based on the DEM-FEM coupling method

The present paper aims to use the concurrent coupling approach of Finite Element Method (FEM) and Discrete Element Method (DEM) to simulate the surface cracking and the local damage in ceramic coating-substrate structures due to mechanical and thermomechanical loading. DEM is an efficient approach for studying the brittle fracture phenomenon at the micro and mesoscale. There are limitations in the use of this method at the macro-scale due to the number of elements. DEM-FEM coupling methods, which take the benefits of both continuous and discrete approaches can be used to reduce the computational effort. In this paper, the bridging domain method which is based on domain decomposition with the overlapping area has been used as the coupling approach. At the mesoscale level, particles with random arrangements were used to discretize the domain. They are bonded with their neighbors using the Timoshenko beam elements. The solver code has been provided by the authors and verified firstly by comparison with the mechanism of surface cracking in ceramic coating obtained from FEM simulation results. Then, the effect of coating thickness, surface crack density, and temperature rise has been investigated on the cracking and interfacial debonding of the ceramic coating. The results demonstrate the importance of temperature changes on the mechanism of damage initiation and evolution in ceramic coating-substrate structures in comparison with pure mechanical loading state.