Multistable mechanical metamaterials for sound absorption

Area of Science:

• Acoustics
• Materials Science
• Metamaterials

Background:

• Achieving high sound absorption at low frequencies and broad bandwidths is a significant challenge in acoustic metamaterial design.
• Existing solutions often lack tunability or structural compactness.

Purpose of the Study:

• To propose and demonstrate a tunable acoustic metamaterial capable of low-frequency broadband sound absorption.
• To leverage multistability for enhanced dissipation mechanisms and robust tunability.

Main Methods:

• Integration of multistable thin-walled tube (MTWT) units with embedded neck structures to create Helmholtz-type resonators.
• Exploitation of multistability to induce acoustic soft boundaries and enhance thermoviscous dissipation.
• Experimental and simulation validation of the proposed metamaterial's acoustic performance.

Main Results:

• The metamaterial achieves near-perfect sound absorption between 436-1141 Hz.
• Continuous tunability of the absorption coefficient from 0 to 1 within the target frequency range.
• Demonstrated robust and energy-efficient tunability through discrete, self-sustained geometric configurations.

Conclusions:

• The proposed multistable acoustic metamaterial offers a novel strategy for multi-dimensional tunability in sound absorption.
• This design shows significant potential for applications in low-frequency broadband noise control.
• The synergistic combination of dissipation mechanisms and tunable states provides a flexible solution for acoustic challenges.