Research On Optimal Design Of Sound Absorption Of Membrane Composite Acoustic Materials

The country is carrying out the revision of the "Noise Law",and because of the epidemic,studying and working at home,people have become more and more aware of low-frequency noise in residential living areas.However,it is more difficult to control low frequency noise than high frequency noise.Traditional sound-absorbing materials-porous materials and microperforated plates are limited by their own properties and cannot take into account both low frequency and broadband high sound absorption.Thin-film acoustic metamaterials,which are relatively easy to design,have strong controllability,and can absorb low-frequency noise below500 Hz,have come into the field of scholars and have become a recent research hotspot.However,thin-film metamaterials still have the problem of narrow sound absorption frequency bands.In this paper,the sound absorption mechanism of the membrane structure is systematically studied,coupled with traditional sound-absorbing materials,and the lowfrequency broadband sound-absorbing performance of the proposed composite soundabsorbing material is verified through experiments,and the structure is further improved by genetic algorithm.optimization.The main research content of this paper is as follows.First,starting from the incidence of plane sound waves,the sound absorption calculation method and sound absorption evaluation index are clarified.The vibration theory of the membrane is studied in detail,and the acoustic impedance and sound absorption coefficient of the additional mass membrane structure are calculated based on the modal superposition method.By introducing the stiffness factor of the membrane,the calculation model is extended to the thin plate structure,and the equivalent is further derived Dynamic mass density and sound insulation expression.Based on the material and structural factors that affect the sound absorption performance of the additional mass film structure,the regulation law of the sound absorption characteristics of the film structure is revealed.The method of finite element simulation analysis using comsol acoustic-structure coupling module is also introduced in detail,and the sound absorption mechanism of the membrane structure is further clarified.Secondly,the sound absorption characteristics of porous materials and micro-perforated plates are explained in detail,and compared with the film structure,the sound absorption frequency bands and advantages and disadvantages of each are clarified.The transfer matrix method is used to calculate the sound absorption coefficient of the porous material/microperforated plate composite additional mass film structure,and the factors affecting the sound absorption performance of the composite structure are analyzed.The finite element simulation of the sound absorption performance of the composite sound-absorbing structure was performed using comsol.Then,the test samples were prepared,and the sound absorption performance of single materials and composite materials were tested using impedance tubes.The test results proved the correctness of the theoretical calculation model.The composite sound absorption structure has low frequency and broadband sound absorption performance.Finally,the sound-absorbing structure is optimized based on genetic algorithm,which is divided into three parts: the optimization of the single-layer additional mass film structure when the variables in the film are continuous,and the single-layer additional mass film when the inherent material parameters of the film are determined.The optimization of the structure and the optimization of the film structure composite micro-perforated plate.The optimization objectives are also divided into three parts: optimization in the wide frequency band of 100-2000 Hz,optimization in the low frequency band of 100-500 Hz,and optimization at a certain frequency.According to the optimized parameters,the sound absorption coefficient curves of the sound absorption structure are drawn.The optimized structures all have good broadband and low frequency sound absorption performance.