Hybrid acousto-elastic metamaterials for simultaneous control of low-frequency sound and vibration

Abstract

Metamaterials have shown great potential for controlling acoustic waves and structural dynamics. Although various types of metamaterials have been developed, simultaneous control of low-frequency sound in air and vibration in solids is less investigated. This paper presents hybrid acousto-elastic metamaterials that enable simultaneous control of low-frequency sound in air and vibration in solids. For the first time, this novel metamaterial adds a compound of membrane and silicone rubber to cladding. The membrane moves the resonance frequency to a low frequency, and the silicone rubber makes the cladding layer rigid enough to support the mass. Bandgap, sound transmission loss (STL), and vibration transmission loss (VTL) were calculated by using the finite element method. Combining modal vibration mode and sound intensity streamline, the mechanisms of vibration isolation and noise reduction were analyzed and then verified through the equivalent mass–spring model. This novel metamaterial combines acoustic metamaterials and mechanical metamaterials to achieve the collaborative control of elastic waves and acoustic waves. At the same time, the peak frequencies of both STL and VTL are lower than those of the traditional metamaterials of the same size, which provides a theoretical basis and method guidance for the next step of collaborative control research of mechanical metamaterials and acoustic metamaterials. It has potential application value in the field of low-frequency vibration and noise control engineering.

Bandgap evolution of metamaterials with continuous solid–liquid phase change

“…When the boundary of unit-cell is subjected to harmonic excitation in z direction, according to equation (12), its equation of motion can be written as:…”

“…Among them, elastic metamaterials have unique vibration isolation performance in the subwavelength segment and peculiar unnatural features such as negative effective mass density [8], negative effective bulk modulus [9], and negative refractive index [10]. Therefore, it is widely used in sound absorption and vibration isolation [11,12], subwavelength focusing hyper lenses [13], thermal energy control [14], and other advanced engineering fields [15]. Based on the principle of generating vibration isolation bandgap, elastic metamaterials can be further divided into Bragg scattering type [16,17] and local resonance type [10,18,19], and local resonance type elastic metamaterials extend the modulation range of phonon crystal waves to a subwavelength frequency band, which is very suitable for the demand of structural low-frequency vibration isolation and noise reduction.…”

Bandgap characteristics of the two-dimensional missing rib lattice structure

“…This paper focuses on the elastic metamaterials that can manipulate elastic waves. Relevant studies have shown that elastic metamaterials can exhibit negative effective modulus and/or negative effective mass density [8] , and have great application prospects in engineering fields, e.g., elastic cloaking [9][10] , noise reduction [11][12] , vibration isolation [13][14] , waveguides [15][16] , and energy harvesting [17][18] .…”

Sound insulation properties of membrane-type acoustic metamaterials with petal-like split rings

“…In a subsequent study, the research team found that multiple ring masses [31] and cell arrays [32] could produce a series of sound transmission loss (STL) peaks to broaden the stopband to some extent. Subsequently, researchers carried out a lot of researches on the low-frequency broadband sound insulation characteristics of MAMs [33][34][35][36][37]. Wang et al [10] adopted constraint sticks to replace the additional mass, which could effectively improve the low-frequency STL bandwidth by adjusting the structural parameters of the sticks.…”