Influence of different internal and external coupling excitations on dynamic characteristics of high-speed railway gearbox housing

The changes in housing vibration acceleration and the influence on various parts of the housing from dynamic stress were interpreted from the perspectives of probability statistics and fatigue damage. Based on vector control theory and multibody dynamics theory for locomotives, a traction motor control model for high-speed train and a rigid-flexible coupling model of high-speed train with a flexible housing were established. The mechatronic coupling model of the high-speed train was constructed through joint simulation. The probability density function curve of housing vibration acceleration was fitted using kernel density estimation. Combined with fatigue testing of housing materials, the damage parameters were calculated. Analysis results show that the probability density functions of vibration acceleration above the small bearing hole in the longitudinal direction, and above the large bearing hole in the horizontal and vertical directions, all undergo a process of changing from a single peak to double peaks. The probability density graphs gradually widen and flatten, indicating that the vibration acceleration in these three directions is significantly affected by excitation changes. When the probability density function exhibits double peaks, they all include wheel polygonal excitation, suggesting that this excitation leads to a more concentrated distribution of vibration acceleration signals on both sides. The fatigue damage contribution from harmonic torque excitation above the small bearing hole and at the oil level observation hole is more prominent, with the damage parameters increasing by about 0.05 at these two locations. These damage parameters remain almost unchanged with the change in working conditions. The fatigue damage contribution from track irregularity excitation above the large bearing hole is the largest, with the damage parameters increasing from 0.14 to 0.68. The fatigue damage contribution from wheel polygonal excitation at the tooth surface observation hole is larger compared to other excitations, with the damage parameters increasing from 0.19 to 0.60. The change in damage parameters at the large bearing hole and the tooth surface observation hole is more significant, so special attention should be given to these areas during maintenance.