An Investigation on the Influence of Multi-damage of Bearings on Axle Box Vibration for Railway Vehicle

As one of the most important parts of the high-speed train rotation system, the axle box bearing mainly supports the rotation of the system and provides additional damping to make the system operate stably. Axle box bearing, as the key to transfer traction power, is susceptible to the excitation caused by the complex status of wheelset. In particular, wheelset is disturbed by wheel-rail wear, wheel polygon and operation line environment, which leads to dynamic uncertainty of its excitation. This makes the vibration response of axle box bearing more complicated. The vibration characteristics and characteristic evolution rule of axle box bearings change with the excitation action, which makes it difficult to monitor, identify and predict the health status of the axle box system. Based on the multi-body dynamics software, the axle box system-vehicle-track coupling dynamics model containing bearing outer race faults and roller faults is established. In view of the local defects and faults of axle box bearings that often occur in the service process of high-speed trains, that is, outer race faults and roller faults as model excitation, the safety threshold of corresponding defects is given by analyzing the influence of different defect widths of outer race and roller for axle box bearing and the influence of compound defect excitation for bearing outer race and wheel flat scar on vibration characteristics of axle box system, which provides the foundation for the health monitoring of axle box system.