Contact problem for an interface crack under action of a moving punch

Nowadays coatings are used in many applications to reduce contact friction, reduce energy losses, improve wear and pitting resistance, and so on in various machine parts. In some cases, coating applications are limited due to coating delamination. The latter is caused by a crack growth due to cyclic loading along a coating interface with the substrate. This paper is focused on modeling and analyzing the behavior of interface cracks between a coating and a substrate. A flat rigid punch subjected to normal and tangential loading is slowly moving along the solid surface. The solid is represented by an elastic half-plane covered by two elastic layers bonded to each other and to the substrate. The elastic materials of the coatings and the substrate are homogeneous but different. The thickness of the layer adjacent to the substrate is considered to be (significantly) smaller than the one above it. This thin layer plays the role of the interface between the other one and the substrate. The interface layer has a crack parallel to its surface and located in the middle of it. The crack surfaces are free from friction and can partially open/close or completely open/close. Some numerical results for the crack stress intensity factors and other solution parameters are presented for cracks small and comparable in size with the punch contact region.