1.School of Mechanical and Vehicle Engineering, Bengbu University, Bengbu 233030, China; 2.National Laboratory of Solid State Microstructures, College of Engineering and Applied Sciences, Nanjing University, Nanjing 210093, China； 3.Anhui Additive Manufacturing Engineering Research Center, School of Mechanical and Vehicle Engineering, Bengbu University, Bengbu 233030, China
Abstract：How to achieve low-frequency broadband sound absorption and design sound-absorbing metamaterials with sub-wavelength thickness has always been a challenging task. A micro-slit folded space metamaterial structure was proposed. The theoretical analytical model and numerical simulation model of the structure were established. The acoustic characteristics and sound absorption mechanism were deeply studied. The influence of typical structural parameters on sound absorption characteristics was analyzed. Based on these, the possibility of realizing low-frequency broadband sound absorption was explored. The results show that by adjusting the thickness of the folded space and the number of folded channels, the peak frequency of the structure can be adjusted in a large frequency band without changing its near-perfect sound absorption performance. Finally, a broadband sound absorption metamaterial was proposed to obtain a continuous and efficient sound absorption bandwidth with an average sound absorption coefficient of 0.931 in the frequency range of 500 Hz ~ 2000 Hz. The thickness of the structure was 5.68 cm, which was only 1/12 of the wavelength corresponding to the lowest resonance frequency. The experimental results were good. The research results can provide reference for realizing broadband sound absorption.
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