A New Life Theory for Rolling Bearings-By Linkage between Rolling Contact Fatigue and Structural Fatigue

Based on a linkage between rolling contact fatigue and structural fatigue, a new life theory for rolling bearings has been proposed using the three-parameter Weibull distribution function. A minimum life is introduced as the third parameter, which may be considered independent from the statistical strength of material. The following are the new findings: (1) Reliability functions and life equations were introduced for the rolling bearing races and the life test specimens made of the same material (JIS SUJ2/AISI 52100), and the linkage between them has successfully been established by using linkage factors. (2) The 90% load rating and rating life formulas for the races as well as for the whole bearing were developed. (3) Newly introduced 100% load rating and rating life formulas were postulated by introducing the minimum lives for the life tests and theoretical research. (4) For the ratios of each load rating between the test results on the grease-lubricated deep-groove ball bearings and the new life theory, the linkage factors were determined as beta = 2.4 and beta' = 2.16 for 90 and 100% load ratings, respectively. (5) A reduction factor lambda for 100% load rating was determined as lambda = beta'/beta = 0.9.