Low-frequency ultra-wide-band-gap petal-shaped local resonance acoustic meta-material

Abstract

The invention provides a low-frequency ultra-wide band gap petal-shaped local resonance acoustic meta-material. The low-frequency ultra-wide band gap petal-shaped local resonance acoustic meta-material comprises a support in the shape of a Chinese character 'tian', elastic films, hemispheres and a plurality of pairs of petal-shaped structures. Square frames periodically extend in x and y directions to form the support in the shape of a Chinese character 'tian'. The elastic films are pasted to the upper parts of the square frames. Corresponding to the square frames, the hemispheres are periodically pasted on the upper parts of the elastic films. The petal-shaped structures are identical in geometrical size, symmetrically surround the peripheries of the hemispheres and are fixed on the elastic films. One square frame, the corresponding elastic film arranged on the upper part of the square frame, the hemisphere and the petal-shaped structures form one cell. The single layer structure made of one kind of cell is adopted for realizing an ultra-wide band gap, the composition or stacking of a plurality of kinds of cells is not needed, the arrangement difficulty of the structure is lowered, and the acoustic stability of the structure is improved; in addition, in a low frequency range, a relative band gap ([delta]f/fc) is as high as 84%, and the proportion of the band gap range in an effect frequency total range is substantially improved.

Description

technical field [0001] The invention relates to the technical field of acoustic metamaterials for low-frequency noise control, in particular to a low-frequency ultra-wide band gap lobe-type local resonance acoustic metamaterial. Background technique [0002] In the past 50 years, with the rapid development of national high-speed trains, aerospace, and large-scale power transmission and transformation projects, noise problems have affected the rapid development of various fields on the one hand, and interfered with people's normal work and life on the other hand. Existing noise control materials are generally passive control structures such as traditional concrete walls and steel plates, or active control equipment with complicated installation and operation. These noise control technologies can effectively control the medium and high frequency noise above 500Hz, but have only a weak attenuation ability for low frequency sound waves below 500Hz. Due to the characteristics of...

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Problems solved by technology

[0004] The above-mentioned acoustic metamaterial structures can produce forbidden bands in a certain frequency range, but the band gap of these acoustic metamaterial structures is not very wide, and the relative band gap (Δf / fc) It is not ideal, and the widening of the band gap is also achieved by stacking multilayer structures or changing the constituent elements of the cells to form composite cells.

On the other hand, the elastic film used in some structures needs to apply tension in advance to generate stress to produce the expected effect. This kind of tension is generally difficult to control and adjust, which increases the difficulty of structural layout. The acoustic stability of the material is also affected, thereby reducing the advantages of acoustic metamaterials as a new type of new material for efficiently controlling low-frequency noise.

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