3D Printed Ultra-thin Acoustic Metamaterials with Adaptable Low-frequency Absorption Performance

The inherent absorption frequency of traditional sound absorbers makes it difficult to solve the problem of acoustic wave removal in a changeable acoustic environment. In this study, acoustic absorption metamaterials (AAMs) with adaptable sound absorption performance were innovatively designed using the structural combination concept and fabricated via 3D printing. Accordingly, two coiled-up channels were combined in a single cell, which could effectively broaden the absorption bandwidth in a limited space. The longitudinal movement of the coiled-up channels endowed the tunable entire depth and internal cavity of the AAMs; thus, the sound absorption performance could be tailored accordingly. Through computational analysis and experimental verification, it was demonstrated that the depth of the AAM could be adjusted from 10 mm to 20 mm, and the corresponding absorption frequencies of the two channels ranged from 206 Hz to 179 Hz and 379 Hz to 298 Hz, respectively. In addition, the finite element results also indicate that the sound absorption bandwidth of AAMs could be further improved by the periodic arrangement of the units. This work opens a promising structural design approach for presenting a route toward acoustic devices with adaptable absorption performances.