Study On Sound Insulation Performance Of Composite Structure Of High Speed Train Car Body

The noise level inside the car directly affects the ride comfort,and improving the noise environment inside the car has become one of the problems that high-speed trains must solve.To reduce the internal noise of the train,generally the sound insulation measures are adopted on the noise propagation path,and the composite structures of the vehicle body are used to attenuate the vibration noise and aerodynamic noise propagating from the outside of the vehicle compartment to the vehicle compartment,that is,a sound absorption and insulation structures are attached on the vehicle body wall panel for insulating the noise.This paper mainly discusses and studies the sound insulation performance of aluminum profile,underframe composite structure and side window of high-speed train car body,and the finite element method,finite element-statistical energy mixing method and statistical energy method are utilized to calculated the structure sound insulation performance according to low frequency,medium frequency and high frequency band,respectively.The main work is as follows:1.The sound insulation performance of the aluminum profile extrusion of the car body underframe is studied.In the low frequency range of 20Hz?630Hz,the finite element model of aluminum profile is established based on the finite element method.In the frequency range of 630Hz-5000Hz,the statistical energy model of aluminum profile is established based on the statistical energy method,and the sound insulation performance of the aluminum profile is calculated and analyzed in the whole frequency range.The method of calculating the weighted sound insulation based on Excel table is discussed,the weighted sound insulation of the aluminum profile is calculated,and the simulation calculation values are compared with test result,the validity and accuracy of the method is analyzed in detail.The acoustic characteristics of the aluminum profile are analyzed in detail,the producing mechanism of the acoustic insulation trough of the aluminum profile is derived theoretically,the resonance frequency and the critical frequency of the aluminum profile are calculated theoretically.The effects of structural parameters such as upper and lower aluminum plate thickness,slab thickness,slab angle,cavity thickness and thickness of upper and lower aluminum plates on the sound insulation performance of aluminum profiles were investigated.2.The sound insulation performance of the composite structure of the car body underframe were calculated and analyzed.Based on the finite element method in the low frequency range of 20Hz-630Hz,the finite element model of the chassis composite structure of "aluminum profile+porous material layer+rubber film+air layer+ glued floor" was established.Based on the statistical energy method in the frequency range of 630Hz-5000Hz,the statistical energy model of the chassis composite structure of "aluminum profile+porous material layer+rubber membrane+air layer+glued floor" was established.The sound insulation performance of the of the chassis composite structure was simulated and analyzed in the whole frequency range,the sound insulation characteristic curve of the composite structure of the chassis were analyzed,and the producing mechanism of the sound insulation trough of the chassis composite structure were discussed.The effect of the structural parameters of the interior trim layer of the chassis composite structure,the porosity of the sound absorption layer,the thickness of the sound absorption layer,the thickness of the air layer,the thickness of the veneer and the thickness of the rubber on the sound insulation performance were analyzed.3.The sound insulation performance of the side window structure of the car body were calculated and analyzed.Based on the finite element-statistical energy mixing method,the finite element-statistical energy mixing model of "tempered glass+PVB rubber+tempered glass+cavity+tempered glass" was established in the middle and low frequency range of 20Hz?1000Hz for the sound insulation simulation of the side window.Based on the statistical energy method,the noise statistical energy model of "tempered glass+PVB rubber+tempered glass+cavity+tempered glass" was established in the high frequency range of 1000Hz-5000Hz for the sound insulation simulation of the side window.The sound insulation performance of the chassis composite structure was simulated and analyzed in the whole frequency range.Based on the sound insulation data,calculated by simulation,the producing mechanism of the anastomosis trough is explained,and the effect of the thickness of the glass,the thickness of the cavity,the thickness of the PVB rubber and the thickness ratio of the double-plate glass on the sound insulation performance of the side window were investigated.The results show that the anastomosis effect between the aluminum profile and the side window is related to the incident angle of the acoustic wave.The acoustic wave of 600?900 causes the aluminum profile to produce an anastomosis effect at 4000 Hz,and the incident acoustic wave of 640?900 causes the side window to have an anastomosis effect at 2500 Hz.Under the lightweight design requirements of the car body,the sound insulation performance of the aluminum profile can be improved by appropriately reducing the thickness of the rib,reducing the angle of the rib,increasing the thickness of the cavity and adjusting the thickness ratio of the upper and lower aluminum plates.The sound insulation performance of the composite structure of the chassis were improved by increasing the thickness of the air layer of the interior layer.The sound insulation performance of the side window were improved by scientifically selecting the thickness ratio of the side window double-plate glass and appropriately increasing the thickness of the cavity.