Graphite-oxide hybrid multi-degree of freedom resonator metamaterial for broadband sound absorption

Abstract

Low frequency broadband sound absorption for thin structures is still a great challenge. A new concept of a stackable hybrid resonator metamaterial is proposed which exhibits super broadband low-frequency sound absorption. The proposed metamaterial is based on micrometric scale thickness Graphene Oxide (GO) embedded in a stacked structure or used as external skin in a designed honeycomb (HC) structure. The stackable nature of the proposed structure allows the GO-HC cores to be embedded within micro-perforated panels (MPP) providing enhanced stiffness/strength to the structure and high absorption characteristics. We demonstrate how the exploitation of the GO elastic and mass properties result in multiple hybrid structural–acoustic resonances. These resonances are tailored to occur in a frequency range of interest by the theoretical calculation of the sound absorption coefficient. The theoretical model combines the mutual interaction between the structural dynamic of the GO foil and acoustic higher modes of the HC core cell as well as stacked MPP-HC/GO-HC cores. The result is a multi-degree of freedom hybrid resonator which provides subwavelength scale broadband sound absorption in low frequency range between 300 and 2500 Hz.

An Investigation of Modular Composable Acoustic Metamaterials with Multiple Nonunique Chambers

“…. ., 16) for MCAM-MNCs-1 could be expressed by Equation (1), and MCAM-MNCs-2 could be expressed by Equation (2). By this method, the influence of adjustment of each chamber was limited to one group, and it had no effect on the chambers in other groups.…”

“…., 16), the desired acoustic absorption property could be achieved. The relationships among the length of each chamber Li (i = 1, 2, …, 16) for MCAM-MNCs-1 could be expressed by Equation (1), and MCAM-MNCs-2 could be expressed by Equation (2). By this method, the influence of adjustment of each chamber was limited to one group, and it had no effect on the chambers in other groups.…”

“…Relative to the common sound-absorbing structures and materials, acoustic metamaterials are treated as the most potential acoustic absorbers to reduce noise [1,2], especially in the low-and middle-frequency range, and many kinds of acoustic metamaterials have been developed [3][4][5][6][7][8]. The absorption property of locally reacting acoustic metamaterials with oblique incidence was analyzed by Jiménez et al [3], which was composed of a slotted panel, each slit being loaded by an array of Helmholtz resonators, and the absorption in the diffuse field took the largest value of 0.951 with an incidence angle around 50.34 degrees.…”