The Study And Optimized Design Of Sound Insulation Performance Of Membrane Acoustic Metamaterials

Sound is an indispensable medium for human communication and development.But in life,it is inevitable that there is a lot of noise that needs to be isolated.Conventional sound insulation materials such as steel plates and brick walls have good barrier effects against most of the noise,but have a poor effect on low-frequency noise.This thesis is based on acoustic metamaterials and focuses on the performance of low-frequency sound insulation in membrane-type acoustic metamaterials.The membrane type acoustic metamaterial is composed of a rigid frame,a tensioned flexible membrane and an additional mass.This thesis carries out simulation calculation and proposes a corresponding experimental scheme for verification analysis.Firstly,the influence of material parameters such as membrane plane stress,membrane thickness,surface density of additional mass,and size of additional mass on the sound insulation performance of the structure was studied by using simulation software.The results show that increasing the membrane plane stress or increasing the membrane thickness,the peak frequency and the valley frequency increase,the peak sound insulation amount becomes larger,and the effective sound insulation bandwidth increases.When the additional mass density becomes larger,the peak frequency and the first valley frequency increase,the second valley frequency hardly changes,the peak sound insulation becomes larger,and the effective sound insulation bandwidth increases.When the additional mass size is increased,the peak frequency increases,the two valley frequencies do not change significantly,the peak sound insulation becomes smaller,and the effective sound insulation width does not change significantly.The additional mass size of the above four parameters has little effect on the sound insulation performance of the entire structure.Then the structure is optimized in order to obtain wide-band noise isolation performance,including different membrane material splicing combined membrane study,same membrane type metamaterials with or without constraint mass studies,and different membrane type metamaterials with or without constrained mass studies.Finally,a two-layer membrane structure with additional magnetic mass is proposed.The shape memory frame is used to change the distance between the two membranes.Magnetic force changes membrane plane stress and mass constraint to achieve intelligent adjustment of the sound insulation range.The feasibility of the method is verified by experiments,and it has great potential in the application of adjustable sound insulation.