Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
LOW-FREQUENCY SOUND ABSORPTION WITH BANDWIDTH EXPANDED BY SYMMETRIC LABYRINTHINE ACOUSTIC METAMATERIAL
Submission Author:
Gildean Almeida , SC , Brazil
Co-Authors:
Gildean Almeida, Erasmo Felipe Vergara, Leandro Barbosa, Robson Zdebski Mikulksi
Presenter: Erasmo Felipe Vergara
doi://10.26678/ABCM.COBEM2021.COB2021-0197
Abstract
Due to the weak dissipation of traditional materials in the region of low frequencies (≤600 Hz), the sound absorption in this region through the acoustic metamaterials (AMM) is of great interest to noise control engineering. In this study, we analytically, numerically and experimentally investigated an AMM composed of a rigid panel containing a micro-perforation of the micro slit type coupled to a multi-cavity of coiled channels. The strategy of symmetrical channels together with visco-thermal losses determines the position of the peak of sound absorption and allows greater control of sound energy. The additive manufacturing technology was used to manufacture the absorber, which was evaluated in the impedance tube technical apparatus for sound waves of normal incidence. Sound absorption of 97% at 242 Hz with a relative bandwidth of 65% was obtained experimentally and showed good agreement with the theoretical and numerical models. This agreement is mainly due to the high dissipation of sound energy in the micro slit region. Therefore, this study reveals the possibility of designing rigid, lightweight structures, and with sub-wavelength dimensions (λ/32), since these structures are of great interest in the fields of engineering acoustics and materials.
Keywords
Acoustic Metamaterial, Low-frequency sound absorption, Additive manufacturing, Sub-wavelength, Visco-thermal effects
