Research On Fatigue Life For Rolling Bearing Based On Multistage Loading Test

As the important components of mechanical products, the reliability of rolling bearing often has a direct impact on the use performance of the whole machine. So forecasting the fatigue life of rolling bearing accurately and effectively has a great importance for our understanding of the running status of equipment. In fact, rolling bearings are often under variable load, which has more complex and more destructive compared with constant load and the failure probability of bearing is higher. The traditional rolling bearing life calculation under variable load is often based on the average payload without considering the influence of load fluctuation on bearing life. Supported by the "National 863 plan project", in view of the load fluctuation's influence on rolling bearing life, in this paper, a life correction calculation method of rolling bearing under variable load is put forward.The theory of L-P based on material subsurface failure needs to compute the bearing internal load distribution. Its calculation method is complex and fails to explain bearing unlimited life. A life correction model, which is based on the theory of I-H-the ISO281-2007 correction method of fatigue life, is established considering the fatigue limit of material in this paper and the influence of pollution and lubrication for the bearing life are discussed and corrects the coefficient of reliability-life according to the characteristics of the domestic bearing. As the same time, considering the load fluctuation influence on bearing life, a correction coefficient of load fluctuation-life is introduced and gets the life correction calculation method of rolling bearing under variable load.According to the characteristic of the test bearing and considering the loading sequence, multistage test load spectrums, which are adapted to this bearing and have different fluctuations, are compiled and the method of accelerated life testing is used to modify the bearing life correction in this paper. A three parameter Weibull distribution parameters estimation method, which is convenient for engineering application, is used to deal with test data and gets the load fluctuation-life correction coefficient under different load spectrum. The final correction calculation method of fatigue life of rolling bearings under variable toad is established and provides a reference for fatigue life prediction evaluation of domestic rolling bearing.In this paper, the relationship between the load fluctuation and the toad fluctuation-life correction coefficient are analyzed. The test results show that their relationship is to inversely proportional and the smaller the load fluctuation degree, the greater the bearing fatigue life. The load fluctuation can reduce the service life of bearing. So for life prediction and reliability evaluation of rolling bearing under variable load should fully consider the effect of load fluctuation on the bearing life.