Improved Method of Roller Bearing Fatigue Life Prediction under Edge Loading Conditions

Abstract

It has been deemed to be proper to use subsurface stress distributions in life predictions of roller bearings under edge loading conditions. But by using this method the decreased life caused by edge stresses is normalized in the process of relating them to the lives of other parts, and therefore life prediction accuracy is lessened. The life calculation method by relating elements is irrelevant in this case. For this measure, an improved method is proposed. It is mainly based on Lundberg and Palmgren's (L-P) theory but differs in calculating the lives where the peak stresses arise; both edges and the center in a full crown roller case, for example. In this method, the center raceway life is corrected by multiplying by the stress uniformity factor. The stress uniformity factor considers the scatter of the material strength, like size effect. It varies according to the uniformity of stress distribution. The results of this method correspond very well to the results of roller endurance testing. In addition, not using the stress uniformity factor results in a good correlation.

KEY WORDS:

• Rolling Element Bearings
• Life Prediction Methods
• Rolling-Contact Fatigue
• Stress Analysis

Review led by Pieter Lugt