A study of spur gear pitting under EHL conditions: Theoretical analysis and experiments

Based on the elastohydrodynamic lubrication (EHL) theory, the roughness of surface topography, the stress of surface and subsurface under pure rolling contact and sliding contact of spur gear are studied. The formation of micropitting, pitting and their sequence is studied with numerical results based on stress field, especially shear stress, by taking into account the high shear tractions caused by local asperity friction. The morphology of micro-pitting and macro-pitting under different stress levels and the distributions of stress are contrast analyzed. The experiments are carry out to investigate the pitting under EHL conditions by using cylindrical roller test machine. The results show that the shear stress of subsurface is a crucial mechanical factor leading to pitting. And pitting is a gradual fatigue phenomenon under the action of the shear stress.