Research On The Structural Design And Sound Insulation Performance Of Double-layer Plate Coupled Membrane Acoustic Metamaterials

As a common sound insulation device in engineering,double-layer plate structure can alleviate the sound insulation valley value by filling sound-absorbing materials.However,the isolation effect of medium and low frequency noise is still difficult to meet the requirements of engineering wholly.Membrane-type acoustic metamaterial is a periodic composite material with negative equivalent coefficient,which has an outstanding effect on the control of low-frequency noise through small structure.In this paper,a kind of double-layer plate structure with built-in membrane-type acoustic metamaterial is designed and fabricated.Through theoretical analysis,finite element simulation and experimental test,the acoustic performance of the structure is analyzed and studied in detail.Through the acoustic coupling of double-layer plate and membrane-type acoustic metamaterial,the peak value of sound insulation appears in the range of sound insulation valley value of double-layer plate,cancelling the sound insulation valley value.The main research contents are as follows:1.According to the sound insulation characteristics of the double-layer plate and the membrane-type acoustic metamaterial,a double-layer plate structure with the built-in membrane-type acoustic metamaterial is designed.The membrane-type acoustic metamaterial is fixed in the cavity of the double-layer plate.The sound insulation model of the double-layer plate and the membrane-type acoustic metamaterial is established and analyzed theoretically,and the finite element analysis software COMSOL Multiphysics 5.5 is further used for detailed analysis.Research on the sound insulation performance of the model are carried out.The results show that under the acoustic coupling effect of the double-layer plate and the membrane-type acoustic metamaterial,the sound insulation peak value appears within the sound insulation valley value of the double-layer plate,offsetting the sound insulation valley value,and the overall sound insulation amount of the double-layer plate in the low and medium frequency range is improved as well(about 4 decibels).The sound insulation performance of the double-layer plate is improved effectively.2.The influences of geometric and material parameters such as the thickness of film,the size of additional mass,the thickness of double-layer plate and the distance between plates on the sound insulation characteristics of membrane-type acoustic metamaterials and double-layer plates are studied in detail.The results show that increasing the thickness of membrane can make the sound insulation peak of membrane-type acoustic metamaterials move to high frequency gradually,from 71 Hz to 374 Hz,and the sound insulation bandwidth has also been significantly widened;Increasing the mass of additional mass block can make the peak value of sound insulation of membrane-type acoustic metamaterials move to the low frequency,from219 Hz to 129Hz;Increasing the thickness of the double-layer plate can make the sound insulation valley value of the double-layer plate move to the low frequency,from 302 Hz to 175 Hz,and the decreasing range is continuously reduced;Increasing the spacing of the double-layer plates can make the sound insulation peak value of the double-layer plate move to the low frequency,from 219 Hz to 129 Hz.The sound insulation valley value of the double-layer plate moves to the low frequency,from214 Hz to 123 Hz,reducing by 91 Hz.Through the above study,the influence of the parameters of the membrane-type acoustic metamaterials and the double-layer plate on its sound insulation characteristics is obtained.3.The influence of the position of the membrane-type acoustic metamaterials in the cavity of the double-layer plate and the membrane tension on the sound insulation performance of the new structure is studied.The results show that the membrane-type acoustic metamaterials in the middle of the two plates can make the acoustic coupling effect of the double-layer plate and the membrane-type acoustic metamaterials reach the best,and can improve the sound insulation performance of the double-layer plate optimally.The change of membrane tension will affect the peak frequency of sound insulation,and lead the acoustic coupling between the double-layer plate and the membrane-type acoustic metamaterials worse.By studying the influence of relevant parameters on the sound insulation performance of the new structure and adjusting the parameters of the membrane-type acoustic metamaterial and the double-layer plate,the peak frequency of sound insulation of the membrane-type acoustic metamaterials is consistent with the sound insulation valley frequency of the double-layer plate,realizing the acoustic coupling effect of the membrane-type acoustic metamaterials and the double-layer plate,so as to cancel the sound insulation valley value of the double-layer plate in the low frequency range,There is a peak value of sound insulation in the valley range,which improves the sound insulation performance of the double-layer plate.4.The sound insulation experiment platform is built to test the sound insulation performance of double-layer plate,membrane-type acoustic metamaterial and double-layer plate coupled membrane-type acoustic metamaterial.Different thickness of double-layer plate,different size of mass block and different thickness of membrane were prepared.The sound insulation characteristics of the designed structure were tested by four sensor measurement method.The experimental data are compared with the results of finite element simulation.The results show that the built-in membrane-type acoustic metamaterial can effectively improve the sound insulation performance of the double-layer plate,and can make up for the weakness of the sound insulation performance of the double-layer plate from the structure.