In this study, we developed a comprehensive three-dimensional vehicle–track coupled dynamics model considering the traction drive system and axle box bearing. In this model, dynamic interactions between the axle box bearing and other components, such as the wheelset and bogie frame, are considered based on a detailed analysis of the structural properties and working mechanism of the axle box bearing. A few complicated dynamic excitations, such as the time-varying mesh stiffness of gears, time-varying stiffness of bearing, bearing gaps and track irregularities, are considered. Then, the dynamic responses of the vehicle–track system are demonstrated via numerical simulations based on the established dynamics model. The results indicate that the traction drive system and track irregularities can significantly influence the dynamic interactions of the axle box bearing. The necessity of considering the excitation caused by gear meshing and track irregularities when assessing the dynamic performance of the axle box bearing is demonstrated.

A three-dimensional vehicle-track coupled dynamics model, with the inclusion of the axle-box bearings, has been developed, which considers the coupling effects between the bearing and the vehicle components. Some non-linear factors, such as time-varying bearing stiffness, bearing clearance, wheel-polygonal wear and the non-linear wheel-rail contact forces, are also considered. Dynamic analysis has been implemented through numerical simulations that consider different amplitudes and harmonic orders of measured and idealised polygonal wheel wear. Both model analysis and validation were supported by field tests. Results show that the roller-raceway contact forces increases with vehicle speed and the amplitude of polygonal wear. However, the influence of wear upon the axle-box bearing is found to be small in the low-speed range, but at higher operating speeds, polygonal wear leads to a rapid increase in bearing contact forces and the potential for degradation. During vehicle operations, both high order (17th to 20th order) and lower order (1st to 4th order) wheel-polygonal wear patterns are generated. The former's influence on axle-box bearing forces is more significant. Hence, the identification and rectification of this order of wear should form part of maintenance practice and potentially also be considered in the design of axle-box bearings for high-speed trains.