An Investigation on the Influence of Misalignment on Micro-pitting of a Spur Gear Pair

This study investigates the impacts of the angular misalignment that is tangent to the plane of action of spur gears on the contact fatigue life of micro-pitting crack nucleation using a computational approach. The governing equations of the mixed elastohydrodynamic lubrication are solved to determine the surface traction distributions. A boundary element-based near-surface stress formulation is implemented for the computation of the multi-axial stress fields, capturing the influence of the local surface roughness topography on the stress concentrations. A fatigue criterion is then used to assess the fatigue damage. The method of circular crown in the lead direction of the gear pair is proposed to alleviate the tooth surface load and lengthen the fatigue life under the misalignment condition. It is shown there exists an optimized crown magnitude, which is dependent on both the misalignment amount and the input torque of the gear pair, for the fatigue life improvement.