Torsional vibration analysis of the gear transmission system of high-speed trains with wheel defects

The gear transmission system of a high-speed train is the key component, which delivers the traction torque from the motor to the wheelset. It couples with the vehicle system via the suspension system, gear meshing and the wheel–rail interface. The dynamic performance of the transmission system directly affects the operational reliability or even the running safety of high-speed trains. In this study, the effects of wheel polygonalisation and wheel flat on the dynamic responses of the transmission system are investigated through simulations of a novel vehicle dynamics model. This model integrates the flexible gearbox housing, the time-varying mesh stiffness and the nonlinear gear tooth backlash, and the track irregularities to obtain more realistic responses of the traction transmission systems in a vehicle vibration environment, from motors to wheelsets, under the effects of the wheel flat and polygonal wear. The field experimental tests are implemented for a vehicle running along a main high-speed railway line in China. Subsequently, the developed dynamics model is validated with good agreement between the experimental and the theoretical results. The calculated results revealed that wheel flat and wheel polygonal wear caused a high-frequency fluctuation of both the longitudinal creep force and the gear mesh force, causing a violent and complex torsional vibration of the gear transmission system. Moreover, the flexible deformation of the gearbox housing, especially its resonance due to the wheel polygonal wear, contributed to the torsional vibration of the gear transmission system.