STUDY ON CAR BODY FLEXIBLE VIBRATION REDUCTION FOR RAILWAY PASSENGER CARRIAGE

High speed and light weight of the railway passenger carriages could cause serious carriage body vertical flexible vibration. In order to find the ways to reduce the elastic vibration, a simplified model of vertical rigid-flexible coupled dynamics for railway passenger carriages is established, in which the carriage body is modelled as a simple uniform Euler beam with free ends. The natural frequencies of the vehicle system components are calculated, and the vertical bending vibration modes are determined for carriage body elastic vibration calculation. The amplitude-frequency characteristics of carriage body elastic vibration is analysed, and the effects of vehicle suspension parameters and carriage body structure parameters on elastic vibration are investigated. The visco-elastic constrained damping layers are suggested to reduce the vertical elastic vibration of the carriage body. Through numerical simulation, it is found that the vibrations calculated by the elastic carriage body model are larger than the rigid body model. The first-order bending vibration has the most important role for the elastic vibration. In order to reduce the carriage body elastic vibration, the first vertical bending natural frequency of the carriage body should be more than times of the natural frequency of vertical rigid mode of the bogie frame, but smaller than the natural frequency of the bogie frame structure vibration. Adequate vertical damping of primary and secondary suspensions, and increased carriage body structure damping should be adopted to attenuate the flexible vibration of carriage body. The use of constrained damping layers can increase the carriage body structure loss factor and hence suppress the carriage body elastic vibration efficiently.