Hybrid acoustic metamaterial as super absorber for broadband low-frequency sound

TLDR

A hybrid acoustic metamaterial (PHCH) is proposed to achieve superior broadband low‑frequency sound absorption while maintaining excellent mechanical stiffness and strength. The design employs a perforated honeycomb‑corrugation core modeled with micro‑perforated panel theory and validated by finite‑element simulations to compute absorption and analyze viscous‑thermal dissipation. The metamaterial achieves near‑perfect absorption at a few hundred hertz with a two‑octave 0.5 bandwidth, dominated by viscous dissipation at perforations, and offers promising multifunctional applications due to its low‑frequency absorption, stiffness, and impact energy absorption.

Abstract

Abstract A hybrid acoustic metamaterial is proposed as a new class of sound absorber, which exhibits superior broadband low-frequency sound absorption as well as excellent mechanical stiffness/strength. Based on the honeycomb-corrugation hybrid core (H-C hybrid core), we introduce perforations on both top facesheet and corrugation, forming perforated honeycomb-corrugation hybrid (PHCH) to gain super broadband low-frequency sound absorption. Applying the theory of micro-perforated panel (MPP), we establish a theoretical method to calculate the sound absorption coefficient of this new kind of metamaterial. Perfect sound absorption is found at just a few hundreds hertz with two-octave 0.5 absorption bandwidth. To verify this model, a finite element model is developed to calculate the absorption coefficient and analyze the viscous-thermal energy dissipation. It is found that viscous energy dissipation at perforation regions dominates the total energy consumed. This new kind of acoustic metamaterials show promising engineering applications, which can serve as multiple functional materials with extraordinary low-frequency sound absorption, excellent stiffness/strength and impact energy absorption.