A Composite Locally Resonant Metamaterials with Acoustic Stop Band

What is it about?

Nowadays in order to reduce automotive noise and enhance passenger comfort, acoustic materials are used as barriers, dampers, or absorbers. Acoustic metamaterials are artificial periodic structures demonstrating features such as resonating or scattering which can effectively reduce the amplitude of incident sound waves in the desired frequency range, creating band gaps. This study presents a composite acoustic barrier metamaterial panel designed with internal resonant structures. To evaluate the effectiveness of the structure compared with conventional sound-barrier materials, cubes consisting of the designed acoustic metamaterial panels were fabricated by 3D printing. Results indicate that the composite metamaterial structure acted extremely well in all frequencies, with a maximum transmission loss (TL) of 17.5 dB, while Plexiglas and MDF cubes achieved a maximum TL of 11.1 dB and 4 dB, respectively.

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Photo by Nivenn Lanos on Unsplash

Photo by Nivenn Lanos on Unsplash

Why is it important?

Another key achievement of the present research was the design of perforated metamaterial panels which can help achieve both noise reduction and a significant weight reduction compared to conventional panels. A key novelty of the present research is to focus on perforated metamaterial panels which can help achieve noise reduction in applications such as ducts, mufflers and vents. The bare metamaterial structure was shown to be effective at certain frequencies and proved that the structure without cover can play a key role in cases where sound attenuation is to be obtained, without affecting the flow of the acoustic media or with significant weight reductions.

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