Numerical interpretation of cone crack initiation trends in a brittle coating on a compliant substrate

Finite element analysis is used to interpret trends in experimentally observed critical loads for contact damage in a brittle (porcelain) coating on a compliant (polymeric) substrate. Different forms of cracking in the brittle layer—both “cone” cracking initiating at the surface, and “radial” cracking at the layer/substrate interface—are considered, with varying coating thicknesses.

The resulting predicted critical loads agree qualitatively with the experimentally observed figures. It is postulated that a previously unexplained peak in critical loads for the onset of cone cracking is caused by a transition between differing modes of cone cracking.