Optimal design method of secondary suspension based on lateral coupling vibration of rolling stock

The hunting frequency of bogie will be close to the natural frequency of rail vehicle's car body at a certain speed, and this can bring the coupling resonance between car body and bogie, which have a bad effect on stability of vehicle. In order to reduce the degree of resonance, a transformed Euclid nearness is selected as the index of modal similarity, and the hunting stability of vehicle is chosen as the control conditions of the model. Moreover, genetic algorithm is used to optimize the second suspension parameter. The results show that, the optimal second suspension parameter can be found by genetic algorithm when the other parameters are constant, and the results are satisfactory. The smaller the coupling degree is, the more gently the damping ratio changes, while the damping ratio of body-yawing or upper-sway is bigger. The smaller the coupling degree is, the stronger the linear of the modal frequency curve is, while the frequency trapping among modes is more unconspicuous. The damping of secondary suspension has a significant influence on the couple between bogie hunting out of phase mode and car-yawing mode and a tiny influence on the couple between bogie hunting in phase mode and upper-sway mode.