Fracture Mechanics Study on Subsurface Median Crack in Layered Structure Subjected to Mechanical Contact

The subsurface transverse median crack system due to spherical contact in brittle coating-bond -substrate sandwich structure is investigated with an emphasis on stress intensity factor near the crack front using finite element method. This crack system emanates from the lower surface of the brittle layer and extends transversely towards the top of contact surface, resulting in ultimate failure of the structures. In this paper, finite element mesh is designed, and the crack front mesh designing solution for a surface crack subjected to remote tension is validated with Newman and Raju empirical equation. Then the proposed crack front mesh design solution is applied to a typical sandwich structure of various modeling parameters to obtain the SIF with 3D-J integral.