Mechanism of Crack Growth in Lubricated Rolling/Sliding Contact

In order to explain the mechanism of rolling-contact fatigue crack growth analytically, fracture mechanics are applied to a semicircular surface crack inclined at an angle to the elastic half-space loaded by Hertzian stresses. It is shown that the surface traction is the controlling factor for lubricant seepage into the crack and for shear mode crack growth rate. It is also clarified that the generation of pits results from tensile mode crack growth mainly due to the oil hydraulic pressure action.