Acoustic Metamaterial Composite Structures Based on Multistage Fano Resonance for Noise Attenuation

An acoustic metamaterial composite structure (AMCS) for Noise attenuation is proposed based on the principle of multilevel Fano resonance. The AMCS is composed of a type I labyrinthine metamaterial in the outer ring, a six-channel spiral metamaterial in the middle ring, a type II labyrinthine metamaterial in the inner ring, and a porous acoustic-absorbing metamaterial in the inner inlay. The simulation results show that the average sound attenuation reaches 17 dB in the range of 0–5000 Hz due to the multilevel Fano resonance effect during the sound wave propagation process. Meanwhile, the sound field distribution law and the flow diagram also verify that the multilevel Fano resonance mechanism is the key factor causing broadband sound absorption. Then, the AMCS is fabricated by 3D printing, and the simulation results are verified by the acoustic experiment for AMCS cell. Additionally, to further enhance the overall sound attenuation in the railroad noise field, a simulation model of the combined train-track-AMCS sound barrier coupling is developed, and it is found that the AMCS type sound barrier can effectively block the propagation of wheel-rail noise from different angles, and it possesses a noise reduction of 20 dB in all frequency bands.