Interior Noise Analysis And Predictionresearch For Straddle-typemonorail Vehicle

In this paper,the straddle-type Monorail vehicle body was taken as the research object.Used the finite element method and the boundary element method to analyze and predict the internal low-frequency structural noise of the vehicle body.Explored the interior noise analysis prediction method and did some groundwork for research work in the future.This paper carried out the following aspects of research work:Firstly,the structure characteristics of straddle-type monorail vehicle body was analyzed in this research.A geometric model of vehicle was established and the structure was reasonably simplified,the FEM model of the vehicle body and the sound-field model of vehicle's interior space were established.The characteristics of vehicle body structure modal,vehicle compartment cavity acoustical modal are analyzed.Secondly,the dynamics model of straddle monorail was established,based on the simulation calculation of dynamics and analyzed the dynamic force spectrum produced by the track irregularity which transmitted from bogies to the four support points of vehicle body,which was produced by track irregularity of bogie is passed to the car body four points of the dynamic load spectrum and use it as input stimulus to calculate the vehicle vibration response in finite element method,and then use the result of vibration response as the velocity boundary conditions of acoustic model,and using acoustic software to solve the vehicle panels vibration radiation noise under the vibration response in acoustical boundary element method.And the interior noise of vehicle body was predicted and analyzed.Then,analyzed the effective of sound-absorbing material on the interior noise,found that it can effectively reduce the interior noise;The sound field distributions of different fields in the range of 10 ~ 200 Hz were given,the characteristics of distributions of interior noise were analyzed,found that the sound pressure level of the vast locations in vehicle body was below 75 dB.However,in 10~30Hz,due to the structural modal and acoustic modal frequencies were close,a coupling effect occurred.Resonance caused in some position and resulting in a larger sound pressure level.Finally,using the method of vehicle body wall panel acoustic contribution,the main structural vibration part of vehicle body structure was determined,and the noise source of main structural was identified.