Influence of the typical operating conditions of urban rail vehicles on vibration and contact characteristics of the axle-box bearing with an outer ring defect

This paper aims to explore the influence of the typical operation conditions of variable speeds and different loads on the contact force and vibration response of the axle-box bearing with an outer ring defect in urban rail vehicles, thereby providing meaningful guidance for the fault diagnosis of the axle-box bearing based on vibration signals and reliability assessments through contact loads under variable working conditions in urban rail vehicles. Therefore, a double-row cylindrical roller bearing (DCRB)-vehicle-track coupling dynamic model was established, which includes a DCRB complete dynamic model with an outer ring defect and a rigid-flex coupling vehicle-track spatial dynamic model. Its feasibility was validated through bench tests and theoretical comparison. It was subsequently employed to simulate the vibration response and contact force of the axle-box bearing with a 2 mm width outer ring defect under various speeds and loads, as well as variable speeds with different loads. The influence on the contact force of the roller-raceway, vibration properties of the axle-box, as well as the variation tendency and stability of vibration statistical indicators were analysed. The results indicate that the changes in speed and load have a greater influence on the contact force of the defective row, and the influence of load changes is greater, with the maximum fluctuation difference between two rows being 0.316 kN. The root mean square (RMS), square root of amplitude (SRA), and peak-to-peak value (PPV) indicators increase monotonically with load and speed. Regarding to the stability of vibration indicators, the shape factor (SF) and the root variance frequency (RVF) indicators are relatively stable. The skewness value (SV) indicator is the worst.