Discrete element simulation of damage evolution in coatings
This paper aims to use discrete element method (DEM) to investigate the cracking and interfacial delamination in ceramic coatings under uniaxial substrate tension. In DEM, the domain of the problem is discretized with a set of dense packing random arrangement of particles bonded together with springs or beam elements. In this method, partial damages can be well described which gives new insights into the qualitative description of damages in ceramic coating/substrate structures. A DEM solver code and dense particle packing generator has been developed by the authors. Yttria-stabilized zirconia is considered as an example of ceramic coatings which is usually used as a thermal insulator for superalloy substrates. A unit cell of ceramic coating/substrate structure was considered with three coating thicknesses and the effect of coating thickness was investigated on damage initiation and propagation. The results showed that the coating thickness affects the damage initiation mechanism. In addition, the structures with thick coatings are more susceptible to interfacial delamination.
Keywords: Ceramic coatings, Discrete element method, Brittle fracture, Damage evolution, Dense packing