Fatigue life prediction of the axle box bearings for high-speed trains

Accurate life prediction of bearings is critical in ensuring the normal run of high-speed trains. However, due to their high running speed, the bearing load of the high-speed trains is complex and exposed to hostile conditions; thus, predicting the life of the bearings by the fixed load using a traditional method is often inaccurate. To solve these problems, the International Organization for Standardization (ISO) 281:2007 and L-P theory bearing life calculation methods are applied in this study, combined with the Miner linear damage theory to propose a bearing life prediction method based on the measured load. Then, on the basis of axle box spring and tumbler load testing technology, the railway line of the motor bogie axle box of CRH380AL high-speed train is measured to obtain the load time history of the spring and tumbler at the typical railway line section, as well as the running speed information of the train. Finally, the predicted life of the axle box bearing under the actual running condition is calculated using this method. Results are compared with the life calculation results using the classic Lundberg-Palmgren theory and the ISO standard method. Results show that the service life calculated by the life prediction method based on ISO standard is the shortest, which is approximately one eighth of that by the ISO standard method; moreover, the calculated service life is significantly longer than the actual overhaul life of the current high-speed train axle box bearing (2.4 million km), indicating that the calculated life is reasonable and safe. The proposed life prediciton calculation method of the bearings can be used to guide the design and the related theoretical research of high-speed train axle box bearings.