Composite 3D-printed metastructures for low-frequency and broadband vibration absorption

TLDR

Architected materials that control elastic wave propagation are essential for vibration mitigation and sound attenuation, yet existing phononic crystals and acoustic metamaterials are limited at low frequencies and narrow bandwidths due to impractical size and mass requirements. The authors introduce elastic meta‑structures that enable wide, low‑frequency band gaps while reducing overall mass. These meta‑structures combine local resonances with lattice structural modes, using Bragg scattering to create band gaps whose size and frequency range can be tuned via lattice geometry, as verified by finite‑element simulations and additive‑manufacturing experiments. The design strategy offers broad applications in controlling structural vibrations, noise, and shock mitigation.

Abstract

Architected materials that control elastic wave propagation are essential in vibration mitigation and sound attenuation. Phononic crystals and acoustic metamaterials use band gap engineering to forbid certain frequencies from propagating through a material. However, existing solutions are limited in the low frequency regimes and in their bandwidth of operation because they require impractical sizes and masses. Here, we present a class of materials (labeled elastic meta-structures) that supports the formation of wide and low frequency band gaps, while simultaneously reducing their global mass. To achieve these properties, the meta-structures combine local resonances with structural modes of a periodic architected lattice. While the band gaps in these meta-structures are induced by Bragg scattering mechanisms, their key feature is that the band gap size and frequency range can be controlled and broadened through local resonances, which is linked to changes in the lattice geometry. We demonstrate these principles experimentally, using novel additive manufacturing methods, and inform our designs using finite element simulations. This design strategy has a broad range of applications, including control of structural vibrations, noise and shock mitigation.