The main objective of this paper is to investigate contact fatigue life models and to evaluate the effect of surface finish on contact fatigue life. The effect of surface finish on contact fatigue life was investigated experimentally using two roller contact fatigue tests. The test samples, i.e. rollers, were carburized, quenched and then tempered. Two different roller surface finishes were evaluated: machined and as heat-treated surface (baseline rough surface) vs. super finished surface (smooth).
Because many factors are involved in sliding/rolling contact fatigue, contact fatigue modeling is still in the early development stage. In this work, we will analyze our contact fatigue test results and correlate contact fatigue life with several empirical contact fatigue models, such as the lambda ratio, a new surface texture parameter, and a normalized pitting model which includes Hertzian Stress, sliding, surface roughness and oil film thickness.
In addition, more advanced three dimensional (3D) rough surface elasto-hydrodynamic lubrication (EHL) analysis was conducted based on the measured surface roughness data and the test conditions of the two roller contact fatigue tests. Sub-surface stress results from the 3D rough surface EHL analysis were used in a classical bearing life model to calculate contact fatigue life. Calculated contact fatigue life was then compared with the test data.