Axle box bearings are crucial components of high-speed trains. Their failure will directly threaten the safety of train operations. Therefore, it is of great significance to study the vibration mechanism of defective axle box bearings. In order to describe the dynamic behavior of the axle box bearing more realistically, this paper presents a dynamic model of cylindrical roller bearing considering the coupling effects of local defects and wheel-rail disturbances based on the model proposed by Gupta. There are 2 degrees of freedom for the outer ring and 3 for the inner ring and each roller in this model. The Hertzian contact force and lubrication traction between the raceway and the roller are taken into account, as well as the gravity of the car body and the wheel rail contact force. In addition, the local defects are described as the time-varying deflection excitations applied to the outer ring, inner ring and rollers respectively. The input of random excitation is achieved by transforming the power spectrum of track irregularity into a time-domain excitation function. The fourth-order Runge-Kutta method is used to solve the equations of motion, and both time domain and frequency domain characteristics of the bearing under different defects are analyzed. The coupling characteristics under different failure conditions are studied. The coupling effect between track irregularity and outer ring and inner ring failure is more obvious, while the coupling effect with roller failure is relatively small. This result provides more theoretical basis for the fault diagnosis of axle box bearings.

Axle box bearings; Dynamic model; Local defects; Track irregularity; Coupling characteristics

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