Vibration and Frequency Domain Characteristics of High Speed EMU

Abstract

When the operation velocity of the high-speed electric multiple unit(EMU) rises to 300 km/h and more,not only the sensitivity of the wheel/rail contact improves,but also the vibration frequency domain of the vehicle system dynamics increases.Therefore,it is important to investigate the vibration characteristics and the dynamics frequency transference from the wheel/rail interface to the carbody of the high-speed EMU.Accelerometers are assembled on the wheelset boxes,bogieframes and carbodies to test the vibration of the vehicle system and air pressure sensors are fixed on the carbody surface to get the air pressure variation when the train passed through tunnels.Based on a field test results implemented on Wuhan-Guangzhou high speed railway,the vibrating accelerations of the axleboxes,bogieframes and carbodies of the EMU on three directions are obtained.Fast Frourier transform(FFT) method is introduced to investigate the vibration frequency and power transference of the sampled data of the EMU running on the typical section including high and low speed division,turnout zone and tunnel passing according to the operation speed chart.The acceleration spectrum is then applied to survey the relationship between the amplitude level and the number of occurrence of the accelerations.The results show that the rotation frequency of the wheelset corresponding to the operation speed and the radius of the wheelset can be found in the frequency domain of the vibration of the wheelset,bogieframe and carbody.Generally,the higher the operation speed is,the larger the amplitude of the accelerations.Intensive vibration occurs when the train passes through the turnout.The aerodynamics has effect on the vibration of the carbody.The main frequency domain of the axlebox,bogieframe and carbody are 400-600 Hz,0-50 Hz and 0-2 Hz,respectively.The spectrum power density and amplitude of the acceleration of the axlebox is decreased by 1 percent and 10 percent approximately from the axlebox to carbody because of the two suspension system of the railway vehicle.