Growth Mechanism of Subsurface Crack Due to Hertzian Contact

Abstract

The variations of three-dimensional mixed mode stress intensity factors for a circular crack under a Hertzian contact pressure moving over the surface are calculated by taking into account both the frictional forces between the crack faces and between the contact surfaces. The circular (penny shaped) crack is assumed to be embeded parallel to the surface. The crack opening occurs near the leading crack tip as well as near the trailing crack tip depending on the pass of the contact load. The crack propagates mainly Mode II, though application of a high surface traction or a heavy contact load can induce the tensile mode crack growth. When the surface traction is directed from left to right, the left side crack tip propagates parallel to the surface and the right side crack tip extends toward the surface.