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Contact mechanics and tribology was combined with fundamental fatigue and fracture mechanics to form a new mechanism for surface initiated rolling contact fatigue. Following, fatigue was investigated numerically for single asperities and craters in lubricated rolling contact surfaces. The hypothesis suggests that asperity point contacts can create sufficiently large tensile stresses for fatigue. The investigated case corresponded to a heavily loaded truck gear with ground surfaces. Reynolds equation resolved the elastohydrodynamic effect of the asperity in the transient three dimensional contacts. The Findley critical plane criterion was used for multiaxial and non-proportional fatigue evaluation. The simulations confirmed the new mechanism for rolling contact fatigue and showed how asperities can create contact fatigue in the lubricated contacts even without slip.

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The rolling contact fatigue damage called pitting or spalling develops more frequently in surfaces with negative than positive slip. Since normal line loads do not cause any tensile surface stresses this investigation considers the effects of small point shaped asperities. Shear traction causes tensile stresses at the trailing edge of asperities entering the contact at negative slip. At positive slip the tensile stresses appear at the leading edge when the asperities exit the contact. It was found that the trailing edge of the asperity breaks through the lubrication film at contact entry. This causes negative slip to be more detrimental than positive slip. At negative slip the location of large frictional shear stresses and tension stresses from normal asperity contact coincide.