A tribo-dynamic contact fatigue model for spur gear pairs

This study proposes a contact fatigue model for spur gears operating under the high speed condition where the dynamic behavior is evident. Realizing the tight relationship between the gear dynamics and the gear tribology, a six degree-of-freedom discrete dynamics model and a mixed elastohydrodynamic lubrication model for spur gears are bridged through an iterative numerical scheme to determine the surface normal pressure and tangential shear under the tribo-dynamic condition, where the gear dynamics and the gear tribology interact. The resultant multi-axial stress fields (from these surface tractions) on and below the surface are then used to assess the fatigue damage. A comparison between the tribo-dynamic and quasi-static life predictions is performed to demonstrate the important role of the gear tribo-dynamics in the fatigue damage. The impacts of the input torque, surface roughness and lubricant temperature on the gear contact fatigue under the tribo-dynamic condition are also investigated.