Effect of Stresses Induced by a Spherical Asperity on Surface Pitting in Elastohydrodynamic Contacts

An attempt is made to correlate some morphological characteristics of pitting cracks with a simple asperity interaction model. The stress field created by a semispherical pressure is combined with the macroscopic Hertzian stress field. For the initiation of fatigue cracks, emphasis is given to two stresses: the maximum range of the superimposed average shear stress over a semicircular area inclined at an angle α to the rolling surface; and the maximum of the superimposed average normal stress over the same semicircular area. Possible mechanisms for initiation of surface pitting are proposed.