The mechanism of bearing surface fatigue - Experiments and theories

This paper begins with a discussion on the limitations of the bearing lubrication parameter, i.e., the Lambda ratio, as well as the variables which influence surface fatigue of rolling bearings, based on close examination of results of bearing tests and peeling tests. Since most rolling bearings in service operate in the ''low Lambda'' regime, the maximum stress in the microcontact of asperities can be much higher than that in the macrocontacts of rolling members. A localized residual stress field is generated as a result of plastic deformation in microcontact. This residual stress contains a tensile component, which is believed to be more detrimental than compressive stress. A new unified bearing surface (micropitting) failure theory is proposed based on the tensile (residual and applied) stress in the material. This theory can be used to quantify the effect of asperity contact maximum pressure, residual compressive stress, tensile hoop stress and hardness on pitting fatigue life.