Prediction of Rolling Contact Fatigue Life in Contaminated Lubricant: Part II—Experimental

In this second part of a two-part paper, experimental fatigue life data on ball bearings operated under different lubrication conditions are correlated to surface damage densities of life tested ball bearing inner rings, as determined by scanning electron microscopy. In Part I [16], five cases of a mathematical model for the prediction of fatigue life in contaminated bearings were presented. These models are fitted to the experimental data given in the present Part II. The correlation coefficient of experimental L₁₀ life with model Case II predictions, based on observed defect densities, is of the order of 0.99 and highly significant for most test groups. One grease lubricated group requires fitting by model Case III. Predicted life dispersion exponents are too high compared to experiment. General data on lubricant contaminant densities show a sufficiency of particles to cause the observed surface damage, but tend to overpredict damage on the basis of the simple particle transport model used. The principal usefulness of the model in its present form is as a tool for the interpretation of the influence on fatigue life of surface damage acquired in service.