A fatigue model for contacts under mixed elastohydrodynamic lubrication condition

A fatigue methodology for pitting crack nucleation is proposed for non-conformal point contacts under mixed lubrication condition where asperity contacts are prominent. The modeling methodology includes: (i) a mixed elastohydrodynamic lubrication model to determine the instantaneous surface contact pressure and shear traction distributions, (ii) a potential theory based stress formulation to compute the three-dimensional, transient, elastic stress fields into the contacting body induced by the surface stresses within the contact zone, and (iii) a multi-axial fatigue criterion to predict the crack nucleation life corresponding to the stress time histories. Given the random nature of the surface roughness profiles of the mating surfaces, a new Lagrangian–Eulerian approach is proposed to quantify the surface roughness effect on the crack nucleation position and life statistically from the deterministic predictions. Additionally, an experimental rolling contact fatigue study is performed and the results are compared to the model predictions to assess the accuracy of the proposed contact fatigue methodology.