Raceway Defect Features of a High-Speed Train Axle Box Bearing in the Vehicle–Track Coupled System

Vibration signals are widely used in condition monitoring and fault diagnosis of high-speed train axle box bearings (HSTABBs). However, there is a lack of mechanism research on the relationship between raceway defects and vibration signals in the vehicle–track coupled mechanical system excited by track irregularity. Therefore, the defect feature and its evolution are explored in this article. Considering the nonlinear contacts between rolling elements, raceways, and cage, the dynamics model of an HSTABB is proposed first. Meanwhile, the raceway defects are performed by the time-varying deflection excitations. Second, a vehicle–track longitudinal–vertical coupled dynamics model integrating HSTABBs is developed. The dynamic interactions between the rotational motions of HSTABB and the longitudinal and vertical motions in the vehicle system are comprehensively involved. Next, the proposed HSTABB dynamics model and the vehicle–track coupled dynamics model are validated by rig tests and field experimental tests, respectively. Finally, the vibration defect features of raceway defects and their evolution law are investigated in time and frequency domain. The results show that the track irregularity has significant influence on the vibration of axle box, causing the defect features very unclear. The raceway fault features of HSTABB are obtained in different defect levels. In addition, the skewness in the selected statistical indicators is the most sensitive to the raceway local defects. The results can provide theoretical support for the health monitoring and fault diagnosis of HSTABB.