Vibration Characteristic Of High Speed Railway Vehicles Considering Body Flexibility And Research On Inner Noise

With the increase of the running speed of high-speed railway vehicles and the lightweight development of vehicles,the overall stiffness of vehicles decreases and the flexible vibration of car body and frame increases.The influence of vehicle flexible deformation on vehicle system vibration cannot be neglected in actual line operation.At this time,the pure rigid model cannot meet the research of vibration characteristics and ride comfort evaluation.With the increase of the flexible vibration of the car body,it will inevitably lead to the increase of the vibration and noise in the car,which will affect the ride comfort of passengers.Therefore,it is of practical significance to carry out the analysis of the vibration characteristics of the flexible car body and the study of the interior noise.Based on the theory of rigid-flexible coupling dynamics,a high-speed railway vehicle dynamic model considering the flexible vibration of the vehicle body is established.The influence of vehicle system parameters on the vibration characteristics is analyzed.The interior noise of the vehicle is studied by acoustic boundary element theory.The coupling effect of vehicle structure and sound and the contribution of vehicle modal acoustics are analyzed.The main research work of this paper is as follows:(1)Establishment of rigid-flexible coupling dynamic vehicle system modelThe theory of modal analysis and substructure analysis are introduced.The elastic car body established by ANSYS is imported into the SIMPACK simulation interface FEMBS and docked with the rigid component of the lower part of the car body to realize the establishment of the vehicle rigid-flexible coupling system model.The mass,inertia and structural parameters of the model are given,and the modal analysis of the elastic car body is carried out.The validity of the model is verified by comparing the measured vibration response data under the same working conditions.(2)Vibration characteristics analysis of suspension parameters of vehicle systemIn order to highlight the necessity of studying elastic vibration,the difference of vibration response between elastic body and rigid body is compared.At the same time,the vibration characteristics are analyzed with the parameters of vehicle suspension system.The results show that:1)the transverse and vertical vibration response of elastic body of high-speed vehicle is obviously larger than that of rigid body,and the change trend of rigid body and elastic body in the first 8 Hz frequency is more consistent.Sexual vehicle body can reflect higher frequency amplitude response;2)For the lateral stifl&iess of primary suspension and the vertical stiffness of secondary suspension,the greater the stiffness,the vibration acceleration of the vehicle body decreases first and then increases,with an optimal value;3)For the vertical stiffness of primary suspension and lateral stiffness of secondary suspension of high-speed train,the greater the stiffness,the vertical vibration of the vehicle body.The greater the vertical stiffness of the primary suspension,the more obvious the impact on the vibration,but the vertical stiffness of the secondary suspension is only significant in the low-speed range.(3)Vibration characteristics analysis of suspension parameters of vehicle systemIn the rigid-flexible coupling dynamic vehicle system model,the suspension system under the vehicle is considered.The vibration characteristics are analyzed by three parameters:the mass of the equipment,the suspension stiffness and the damping of the elastic element.The results show that:1)The greater the quality of suspension equipment,the smaller the lateral and vertical vibration acceleration of the car body,and the larger the vibration acceleration of the equipment,so it is necessary to monitor the vibration of the equipment and balance the vibration control of the elastic car body and suspension equipment;but when the equipment is distributed in the longitudinal direction,it can effectively avoid the deterioration of the equipment vibration caused by the excessive mass ratio;2)The greater the stiffness of the equipment.The transverse and vertical vibration acceleration of the car body and the equipment vibration acceleration decrease first and then increase,and the stiffness has the optimum value,which can ensure that the equipment vibration does not deteriorate significantly.3)With the increase of the equipment damping,the vibration reduction effect of the car body is not obvious,mainly reflected in the reduction of the equipment vibration,but in the longitudinal distribution of the equipment,the restraint of the equipment vibration will be weakened to a certain extent.4)After considering the accessory equipment of the car bottom,the elastic vibration of the car body increases at 300 km/h and 400 km/h,and the resonance of the car body and the equipment will occur.(4)Research on the interior noise of flexible car bodyIn order to get the relationship between vehicle vibration and vehicle interior noise,the acoustic contribution of vehicle interior sound field is analyzed.Based on the acoustic boundary element theory and acoustic modal analysis method,the boundary element model of the car body is established.The measured train acceleration is used as the excitation.Based on the interaction of structural vibration and sound,the acoustic contribution analysis and noise optimization of the car body modal are carried out.The results show that:1)the noise in the car mainly concentrates in the low frequency band,and there are abnormal peaks at the target site.With the increase of the frequency,the acoustic contribution of the car body modal is analyzed and optimized.The field distribution presents complexity;2)modal participation factors are mainly concentrated within the first 35 Hz,corresponding to the peak frequency of the sound pressure level at three target fields,and the vibration of the car body structure will affect the distribution of the sound pressure level in the car;3)the acoustic transfer vector nephogram reflects the panel contribution of the peak frequency,which proves that the excitation of the car body vibration loaded on the floor has a direct impact on the sound pressure level distribution of the noise;Abnormal peaks occur at 10Hz in all panels.The first three local vibration modes are obtained by contribution analysis.When the panels are thickened,the change of the thickness of the panels can reduce the sound pressure level at the peak frequency of the target site and achieve the purpose of vehicle noise reduction optimization.