Study On Vibration Characteristics Of Carbody And Underframe Suspended Systems Of High Speed Trains

With the increasing of the comprehensive national strength,Chinese high-speed railway has developed very fast which possesses the advantages of fast speed,convenience,large load capacity,energy saving and environmental protection and has completely changed the way people travel.However,the coupling vibration between the carbody and underframe equipment deteriorates the passenger riding comfort.In this paper,the vibration characteristics of high-speed train carbody and underframe equipment are studied extensively.Firstly,Collecting the test data of a certain type of CRH running on the Beijing-Shanghai line,through the measured data analysis,it is known that:When the carbody harmonic vibration occurs,the vibration main frequencies of carbody and auxiliary converter are around 8.75 Hz.Vibration amplitude from the auxiliary converter to auxiliary converter hanging bracket and to the carbody pillow reduces in turn.Then,the rigid-flexible coupling dynamic model of vehicle system is established.The influence of different mileage,track random excitation and random crosswind on the vibration characteristics of the carbody and underneath equipment are analyzed in turn.Through the measured data of the wheel tread wear and simulation using the rigid ?flexible coupling dynamic model,and changing the stiffness,damping ratio and mass of the underframe suspended system,the vibration feature of carbody and underframe equipment under different parameters are calculated.From the viewpoint of the carbody vibration reduction,the optimal parameters of underframe suspended system are determined.The track spectrum,including the Wuhan-Guangzhou,the Beijing-Tianjin track spectrum and the German low-interference spectrum track irregularity and their impact on the vibrations of the carbody and underframe equipment are analzed.The simulation results show that the carbody rigid and elastic vibrations exist simultaneously at high speed.The rigid motion and elastic vibration of the carbody caused by Wu-Guang spectrum are greater than the other track spectrums..The vertical load and the lateral load of the suspended system reach the maximum around 15Hz.Considering the random cross wind on the carbody,the simulation results show that the lateral acceleration of carbody and the load of the underframe suspend system under the low speed wind are obviously increased in the low frequency range(0?8Hz)compared with no wind.When the crosswind speed increases,the lateral vibration of the carbody increases obviously in 0?5Hz and 15-20Hz,and the lateral vibration load of the underframe suspended system increases obviously in the low frequency region.Finally,the rigid-flexible coupling dynamic model of the train is adopted.By applying a certain traction or brake torque on the leading wheelset of the head car,the longitudinal vibrations of carbody and underframe equipment under traction and brake conditions are investigated.It is known that the longitudinal and lateral elastic vibrations in the middle of the carbody are concentrated in the range of 12 Hz and 20 Hz at the end of the traction and beginning of the braking.When the braking acceleration increases to 2m/r2 the amplitude of longitudinal elastic vibration of the carbody increases significantly at about 25Hz,and the longitudinal load of the underframe suspended system does not change too much.