Research On Acoustic Performance Of Vehicle Panel Sandwiched With Magnetorheological Fluid

With modernization of industrial production and development of traffic and transportation industry,noise pollution has become more and more serious.Some new materials and new structures for sound absorption and noise reduction,sound insulation and noise reduction have been continuously proposed.In this context,a magnetorheological fluid(MRF)sandwich panel structure is proposed,which is expected to be used for vehicle body panels or roof panels.And this sandwich panel structure are taken as the research object,a method combining theoretical modeling,numerical simulation and experimental research is used to perform a systematic research on the acoustic performance of the sandwich panel structure.The main research contents and conclusions in this paper are summarized as follows.(1)Theoretical study on acoustic performance of MRF sandwich panels.Firstly,the mathematical model of sound transmission loss of sandwich panels was established based on wave impedance analysis method.Secondly,based on the established mathematical model of sound transmission loss and material properties of magnetorheological fluid,sound transmission loss calculation program of MRF sandwich panels was compiled.Finally,based on the sound transmission loss calculation program,the influence of the excitation current,the MRF core layer thickness,the sanswich panel surface layer thickness and the surface layer material properties on the sound transmission loss of sandwich panels was researched.The research results show that the excitation current has obvious effects on improving the sound insulation performance of the MRF sandwich panel;the first anastomosis frequency of the sandwich panel was reduced with the larger core layer thickness,which is unfavorable for the low-frequency sound insulation performance of the sandwich panel;the first resonance frequency and the resonance number in high frequency region should be considered into the choice of the sandwich panel surface layer thickness;the sound insulation performance of sandwich panels in high and low frequency and the lightweight requirements should be considered into the choice of the sandwich panel surface panel materials.(2)Finite element simulation study on the acoustic performance of MRF sandwich panels.To explore the influence of MRF column in sandwich panels on acoustic performance of MRF sandwich panels Based on ANSYS software,the acoustic finite element model of the MRF sandwich panel with different structural forms were established,and the acoustic properties of MRF sandwich panels were studied.Based on the established acoustic finite element model of MRF sandwich panels,the effects of magnetic field intensity,different MRF column heights,and different arrangement position of MRF columns on the radiant sound pressure level of the sandwich panel were studied respectively.and a comparative study of the maximum radiated sound pressure level between the MRF sandwich panel and a vehicle body roof was conducted.The research results show that the core layer thickness of the MRF sandwich panels has a significant effect on the sound transmission loss of the MRF sandwich panel,and the larger core layer thickness is beneficial to the active control of the sound insulation of the MRF sandwich panel;with the increase of magnetic field intensity,the maximum radiated sound pressure level of the MRF sandwich panel decreases overall,and the frequency corresponding to the peak value of the radiated sound pressure level increases;the degree of influence of the magnetic intensity on the maximum radiated sound pressure level of the MRF sandwich panel is greatly affected by the arrangement position of the MRF column in the core layer;the maximum radiated sound pressure level of the MRF sandwich panel is significantly lower than that of a conventional vehicle body roof with the same size.(3)Experimental study on sound insulation of MRF sandwich panels.Firstly,the hardware platform of the sound transmission loss test system for MRF sandwich panels was constructed.Secondly,the software program of the test system was designed using LABVIEW.Finally,the sound transmission loss of the MRF sandwich panel was measured using the test system.The test results show that the magnetic field intensity added to the sandwich MRF column has a certain influence on the sound transmission loss of the sandwich panel,but the influence of magnetic field intensity on the sound transmission loss of different sandwich panels is different;the sound transmission loss regulation of the sandwich panel can be realized by changing the magnetic field intensity added to the MRF column,or by applying the same magnetic field intensity to different MRF columns.This study laid a theoretical foundation and design reference for the active control of the sound transmission loss of the MRF sandwich panel.