Abstract: When the high-speed train passes the bridge at the speed of 150～200 km/h, there will be the nod vibration and it will reduce the Vehicle stability. In order to reduce the nodding resonance, a semi-active secondary vertical damper is proposed to replace the passive damper of the original vehicle. A semi-active damper with adjustable performance parameters is designed and a simulation model is established, and the accuracy of the model is verified by experimental comparison. It shows that the semi-active damper can replace the original passive damper to adjust the damping performance. Based on the control strategy of vehicle semi-active damper, the co-simulation model of damper and vehicle dynamics is established, and the dynamic behavior of vehicle crossing bridge and driving on normal line under different damper states is analyzed. The results show that the performance of the semi-active damper and the passive damper is basically the same in the railway without bridge excitation. In the railway with bridge excitation, the semi-active damper can effectively weaken the nodding resonance of the vehicle crossing the bridge, and the vibration amplitude near the resonance frequency is significantly reduced. Compared with traditional passive vertical damper vehicles, the dynamic performance of high-speed train equipped with semi-active damper is better in the operating speed range where nodding vibration is easy to occur.

Key words: semi-active secondary vertical damper, bridge excitation, nodding vibration, semi-active control