Establishnent of a New Rolling Contact Bearing Life Calculation Method

Rolling bearings for aircraft gas turbines and power drives are designed to meet endurance requirements basically determined according to the Standard fatigue life calculation method. This method is based on Lundberg-Palmgren fatigue life theory as modified by reliability, material and lubrication factors. As aircraft load and speed requirements increase, this method results in bearings of increasing size, significantly adding to the size and weight of the gas turbines and power drives. Newly developed life prediction methods recognize the existence of a fatigue limit stress. If the stresses an operating bearing experiences do not exceed the limit stress, the bearing can achieve infinite life. Bearings designed using these new methods will have smaller diameters, weigh less and cost less. This Phase I project will investigate these new methods and analytically evaluate the utility of each by comparing fatigue lives so predicted with actual fatigue life data accumulated by aircraft engine and power drive manufacturers. To conduct the evaluation, computer programs BBEAN2 and CYBEAN2 will be used for bearing performance analysis. Assuming reasonably successful comparison of actual and analytical data, a Phase II project will further develop a practicable method using the fatigue limit stress for aircraft bearing design.