Finite subsurface crack under surface loading

Using interface elements between the crack faces, the problem of a subsurface crack parallel to the surface of a half-space was studied by the finite element method. The traction is applied on the surface of the half-space and the Coulomb friction law was used in the contact crack faces. For uniform tensile loading the finite element method gives the same result as the dislocation model and no contact between the crack faces was found. For uniform shear loading, crack faces contact each other at the tail end of the loading direction. It is found that the stress intensity factor, K_II, at the closed crack tip for frictionless contact between the crack faces is larger than that at the open tip and all the stress intensity factors increase as the subsurface crack approaches the surface.