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

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.