Fatigue Life of Anti-Friction Bearings Subjected to Cyclic Loading

Cyclic loading is defined as external loading that varies within the revolution of a bearing and is repeated for every revolution. The cyclicly varying loads may consist of a series of discrete loads that occur in a repeating pattern or a continuously varying force or a combination of these. A simple example of cyclic loading is a single cylinder, double acting piston pump in which the force on the bearings reverses every 180° of a revolution; as a result, the same half of the rotating bearing race passes under the load twice in a single revolution. More complex patterns of cyclic loads occur in rotary engines, fuel injection pumps, nutating engines, etc.

The paper presents the theoretical relationships and methods that predict the effect of cyclic loading on the fatigue life of anti-friction bearings. An example problem solved with the aid of a special analysis program illustrates the results from these methods.