AUTHOR=Wu Fei , Zhang Xiao , Ju Zegang , Zhao Jiang , Hu Man , Gao Mingyuan , Luo Jun , Pu Huayan 

TITLE=Ultra-Broadband Sound Absorbing Materials Based on Periodic Gradient Impedance Matching

JOURNAL=Frontiers in Materials

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/materials/articles/10.3389/fmats.2022.909666

DOI=10.3389/fmats.2022.909666

ISSN=2296-8016

ABSTRACT=Ultra-broadband sound absorption with periodic gradient impedance matching is of great concern in research of acoustic materials. This paper investigates the impedance matching of composite acoustic metamaterials composed of micro-perforated plates and subsequent Fabry-Pérot(FP) channels. Based on the impedance matching theory, ultra-broadband sound absorption has been realized through a design with 36 channels whose thickness is only 50mm. Also, the average sound absorption coefficient of 88% and an absorption frequency bandwidth (490-4000hz) can be achieved by preserving the matching impedance. Furthermore, in changing the thickness of the perfect absorber being 100mm, the average sound absorption coefficient can reach greater than 90% in the frequency range of 250-4500hz. The proposed structure is validated analytically and experimentally. This work can help with the designing and improving method of acoustic metasurface and especially have the potentials in ultra-broadband sound absorbers design.