Acoustic perfect absorption and broadband insulation achieved by double-zero metamaterials

Abstract

We report the mechanism for simultaneous realization of acoustic perfect absorption (PA) and broadband insulation (BI) in the acoustic free field by a layered acoustic metamaterial (LAM). The proposed LAM comprises two critically coupled membrane-type acoustic metamaterials sandwiching a porous material layer. Both theoretical and experimental results verify that the proposed LAM sample can achieve nearly PA (98.4% in experiments) at 312 Hz with a thickness of 15 mm (1/73 of wavelength) and BI in the frequency range of 200–1000 Hz with an areal density of 2.2 kg/m2. In addition, the real parts of both the effective dynamic density and bulk modulus reach zero precisely at the critical frequency of 312 Hz, arising from the monopolar eigenmode of LAM. Our work advances the concept of synthetic design of sound absorption and insulation properties of multi-impedance-coupled acoustic systems and promotes membrane-type acoustic metamaterials to more practical engineering applications.

An analytical model for broadband sound transmission loss of a finite single leaf wall using a metamaterial

“…It is known from the literature that this kind of arrangement, referred to as metamaterials, produce a frequency band where free wave propagation is not possible. Near this band gap is where sound transmission will be at its lowest [8][9][10][11][12][13][18][19][20], so being able to predict or tune this band gap to a particular frequency range is of interest. It is important to understand which parameters play a role and how they influence this phenomenon.…”

“…The definition may be broadly interpreted as systems or materials that display (as a whole) extraordinary properties not found in natural materials with respect to sound and vibration characteristics, such as negative apparent mass and/or bulk modulus. Metamaterials can show high transmission loss (TL) at low frequencies despite having low mass per unit area [8][9][10][11][12][13]. They owe this behaviour to internal subwavelength periodic structures.…”

“…Band gaps can be introduced into these structures by mounting an array of resonators to them. This type of construction has been studied and validated in recent years [8][9][10][11][12][13].…”

Engineering Coiling‐Up Space Metasurfaces for Broadband Low‐Frequency Acoustic Absorption

“…AMMs render new ways for acoustic attenuation on noise control . Dark acoustic metamaterials, made of thin films decorated with asymmetric rigid platelets, have been presented for low‐frequency sound absorption .…”

Tensegrity cell mechanical metamaterial with metal rubber

“…The MR also contributes to dissipate energy and stabilize the response of the tensegrity up to 330 Hz. The reason behind the stiffening and dampening effect is its increasing equivalent storage modulus (3)(4)(5)(6)(7) for frequencies above 150 Hz of the MR, and loss factors all above 15% 28 .…”