An investigation on dynamic vibration characteristics of urban rail vehicle axle-box bearings in the presence of rail welds

The operation condition of axle-box bearings strongly affects the running safety of vehicles. However, the presence of rail welds can impact the wheel-rail interaction system, causing changes in the dynamic response of axle-box bearings and furtherly affecting their health condition. Despite this, there is still a lack of discussion and analysis on the effect of rail welds on dynamic characteristics of axle-box bearings. Therefore, a vehicle-track coupling dynamics model is developed. Besides the rigid vehicle model, flexible track model and wheel-rail contact model, the axle-box bearing model and flexible wheelset model are considered. Among them, the axle-box bearing model accounts for the motion of the roller and cage decentralized into multiple segments. Using modal superposition method, the flexible deformation of the wheelset is calculated and overlapped with its rigid displacement for the flexible wheelset model. The performance of the model is verified through theoretical analysis and field tests. It is crucial to consider the wheelset as flexible in the presence of rail welds and its effects are also researched. Moreover, the effect of the rail weld geometry on the wheel-rail separation is studied, and the consequence caused by rail welds on the bearing damage is discussed under different vehicle speeds.