Broadband low-frequency sound absorption characteristics of a negative Poisson's ratio nested honeycomb metamaterial

A negative Poisson's ratio nested honeycomb metamaterial (NPRNH) is proposed to achieve ultra-broadband low-frequency sound absorption. The sound absorption characteristics and underlying physical mechanisms are systematically analyzed through theoretical modeling, finite element simulations, and experimental measurements. Results demonstrate that the NPRNH structure achieves quasi-perfect absorption coefficients of 0.97 and 0.96 at 656 and 839 Hz, respectively, with an overall thickness of only 23 mm (approximately λ/23) and a half-absorption bandwidth of 440 Hz. Complex-frequency analysis and sound field distributions reveal that the dual absorption peaks originate from the coupled resonance between the negative Poisson's ratio effect and the honeycomb structure, significantly enhancing energy dissipation and impedance matching. Parametric studies indicate that the absorption performance can be flexibly tuned by adjusting the aperture, number of perforations, honeycomb core width, and cavity depth. This study provides a novel approach for developing broadband and efficient low-frequency sound-absorbing materials.