Sound-absorbing continuous fiber-reinforced composite metastructure

Noise mitigation in applications involving extreme environments with combined structural strength and acoustic control, such as aerospace, transportation, and construction, faces critical challenges due to the trade-off between sound absorption and mechanical integrity. Traditional porous absorbers offer good acoustic performance but are structurally weak, lacking the stiffness and durability needed for load-bearing applications. Moreover, their performance in the low-frequency range often requires bulky designs, limiting their use in compact or weight-sensitive systems. In this study, we introduce a multifunctional composite metastructure that combines a Fabry-Pérot acoustic channel design with a custom-developed continuous fiber-reinforced additive manufacturing process. Using a dual-nozzle robotic arm and path-optimized printing, we fabricate a compact metastructure capable of broadband noise absorption and high mechanical robustness. The metastructure achieves an average sound absorption coefficient exceeding 0.9 across 1 500-5 500 Hz, as confirmed by coupled-mode theory and impedance tube experiments. We further demonstrate that continuous fiber reinforcement significantly enhances the bending, compression, and shear performance of the composite metastructure compared with its short fiber counterpart. This work offers a scalable platform for advanced multifunctional materials with strong potential in extreme environments, such as aerospace noise control, advanced transport systems, and lightweight architectural design.