A Reassessment of Lambda Ratio as a Bearing Surface Fatigue Performance Indicator

For about three decades, the Lambda ratio, i.e. the ratio of Ehd film thickness to the composite surface roughness has been used as an indicator for bearing lubrication as well as the basis for bearing load rating improvement. Although the film thickness and the Lambda ratio are relatively independent of load, the initiation of surface fatigue, or micropitting is load dependent. Furthermore, in the low Lambda region, the bearing surface fatigue and life ratio are more dependent on roughness than on film thickness. This paper reexamines the role of Lambda ratio and other parameters on bearing surface fatigue and bearing life ratio, by taking into consideration the severity of asperity interactions and microplastic deformation,