EFFECT OF TEST RIG STRUCTURE PARAMETERS ON CONTACT STRESS OF SPECIMEN

By using a new type pure rolling fatigue test rig with three contact points for silicon nitride bearing ball specimen, the stress relative difference value of a specimen with three contact points is, according to elastic contact theory, calculated while test rig being different parameters under a rolling contact condition. The effects of the driving roller and concave arc and roller radius on the stress relative difference value of the specimen are analyzed. The numerical results indicate that the stress relative difference value of specimen is less than 1% when the driving roller radius is 25mm, concave arc radius is 40mm, roller radius is 12.5mm and the specimen radiuses change from 4.25mm to 10.5mm. The appropriate decrease of specimen radius scope can reduce the stress relative difference value of a specimen. The less stress relative difference value is, the less the effect on the specimen life is.