Ultrathin multi-slit metamaterial as excellent sound absorber: Influence of micro-structure

S. W. Ren, H. Meng, F. X. Xin, T. J. Lu

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26 Citations (Scopus)

Abstract

An ultrathin (subwavelength) hierarchy multi-slit metamaterial with simultaneous negative effective density and negative compressibility is proposed to absorb sound over a wide frequency range. Different from conventional acoustic metamaterials having only negative real parts of acoustic parameters, the imaginary parts of effective density and compressibility are both negative for the proposed metamaterial, which result in superior viscous and thermal dissipation of sound energy. By combining the slit theory of sound absorption with the double porosity theory for porous media, a theoretical model is developed to investigate the sound absorption performance of the metamaterial. To verify the model, a finite element model is established to calculate the effective density, compressibility, and sound absorption of the metamaterial. It is theoretically and numerically confirmed that, upon introducing micro-slits into the meso-slits matrix, the multi-slit metamaterial possesses indeed negative imaginary parts of effective density and compressibility. The influence of micro-slits on the acoustical performance of the metamaterial is analyzed in the context of its specific surface area and static flow resistivity. This work shows great potential of multi-slit metamaterials in noise control applications that require both small volume and small weight of sound-absorbing materials.
Original languageEnglish
Article number014901
Number of pages9
JournalJournal of Applied Physics
Volume119
Issue number1
Early online date5 Jan 2016
DOIs
Publication statusPublished - 7 Jan 2016
Externally publishedYes

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