Subhertz band gaps in ultralightweight inerter-based metamaterials
Phys. Rev. Applied 25, 024032 – Published 10 February, 2026
DOI: https://doi.org/10.1103/nwvf-n7lg
Abstract
Resonator-based acoustic metamaterials are renowned for their ability to control wave propagation at low frequencies. Nevertheless, achieving band gaps at ultralow frequencies—critical for applications such as seismic protection—has been hindered by the need for excessively heavy resonator masses, often surpassing the weight of the structures they are designed to protect. In this study, we introduce an approach using inerter-based metamaterials that leverage translation-rotation coupling to achieve amplified inertia without the associated mass penalties. It enables band gaps in the subhertz to several hertz ranges while reducing the embedded mass by 3 orders of magnitude compared to resonator-based systems. Through a combination of analytical modeling, numerical simulations, and experimental validations, we demonstrate robust band-gap formation for both longitudinal (0.4–1.0 Hz) and transverse waves (4.6–6.2 Hz) using compact lightweight units. This paradigm shift breaks the long-standing trade-off between resonator mass and operational frequency in resonator-based metamaterials, paving the way for practical low-frequency wave attenuation in diverse engineering applications, including seismic shielding and aerospace vibration control.
