Research On Sound Insulation Characteristics Of Combined Acoustic Metamaterials

With the development of society and the advancement of technology,people have higher and higher requirements for the comfort of life.Noise is an important factor that affects people’s comfort and affects people’s physical and mental health.Ship noise is mainly generated by the ship’s main engine and other large-scale equipment,which not only affects the comfort of the staff,but also has an important impact on the normal operation of the equipment and the overall stealth performance of the ship.Therefore,it is very important to control the propagation of ship noise.Traditional sound-absorbing and insulating materials can achieve excellent soundabsorbing and insulating properties in high frequency bands.For example,honeycomb sandwich panel structure is widely used for noise control in ships,but due to the influence of the law of quality,large surface quality is often required in the low frequency stage.The density and thickness can achieve a good sound absorption and insulation effect,which increases the quality of the material itself,which goes against the requirement of light weight.The emergence of acoustic metamaterials provides a new way to solve this problem.Acoustic metamaterials possess some special acoustic properties that natural materials do not possess,such as negative mass density and negative bulk modulus.By using these acoustic properties,it is possible to control the propagation of sound waves,thereby satisfying the control of sound waves in engineering practice.In this paper,combining the advantages of honeycomb sandwich panel structure and acoustic metamaterial structure,the hemming honeycomb structure sandwich panel and membrane acoustic metamaterial are combined to study the sound insulation characteristics of the combined acoustic metamaterial.Firstly,starting from the basic theory of acoustics,the relevant knowledge of the plane wave equation,the law of mass action and the basic laws of sound insulation are introduced.Based on the modal analysis method and the equivalent method,the sound insulation expression formula of the membrane acoustic metamaterial and the sound absorption of the Helmholtz resonant cavity are derived.The expression relationship between frequency and various structural parameters of the cavity theoretically reveals the sound insulation law of acoustic metamaterials.Secondly,use the finite element simulation software COMSOL acoustic module to perform sound insulation simulation analysis on the acoustic metamaterial structure,and analyze the membrane-type acoustic metamaterial at different membrane tensions,different membrane thicknesses,different membrane sizes,mass positions,and mass masses.The specific influence of double-layer membrane on its sound insulation.Then on the basis of the membrane acoustic metamaterial,the honeycomb hemming structure is introduced,and the honeycomb hemming-membrane combined acoustic metamaterial structure is designed,and the comparative advantages of this structure and the traditional straight-edge structure are discussed.Finally,from the experimental point of view,the sound insulation laws of the two metamaterial structures designed with straight edges and folded edges are further analyzed and verified,and the results are compared with the numerical simulation results to verify the reliability of the results.The honeycomb hemming-membrane combined acoustic metamaterial structure proposed in this paper is redesigned and optimized on the basis of the membrane acoustic metamaterial.Compared with the traditional honeycomb straight edge structure,it has a better low-frequency sound insulation effect,which is a practical transformation of engineering and provides a theoretical basis.