Abstract: The function of the dampers is to produce the damping forces to suppress the vibrations of the railway vehicle. Therefore,the dampers have great effect on the high speed vehicle system dynamics. Lots of presented studies dealt the dampers as damping force element to study the dynamics of the vehicles. However, the dynamic characteristics of the loads of the dampers are little investigated from the view of vehicle system dynamics and structural reliability. In order to obtain the load characteristics of the dampers of the high speed electric multi-unit(EMU), four kinds of dampers are manufactured to measure the forces of the yaw damper,axlebox damper, lateral damper and vertical damper of the secondary suspension. The forces are measured with field experiment at Datong-Xian high speed delicate line. After dealt with the sampled data, the forces of the four kinds of dampers are obtained. The dynamic characteristics of the damping forces are analyzed in time domain and frequency domain. Rain flow count method are introduced to implement the loads count. The load distributions are presented with different operation speed of the train. The results show that, among the four types of damper forces of this type of EMU, the peak load of the yaw damper is the largest and the peak load of the lateral damper of the secondary suspension is the smallest. The velocity of the axlebox damper is the largest and the velocity of the lateral damper of the secondary suspension is the smallest. The operation speed of the train has great influence on the damping loads. The forces of the dampers distribute in a nearly normal fashion. The effect of the curve radius of the track on the main section on the loads of the axle damper, secondary vertical and lateral suspension damper is negligible. Operation speed and tough curve have effects on the loads of the yaw dampers.

Key words: high speed electric multi-unit(EMU), damping forces, dynamic characteristics, loads distributions, field measurement