Low-frequency sound-absorbing metasurface with a channel of nonuniform cross section

Abstract

In this letter, we propose a theoretical description of double nonuniform cross-section (DNUCS) channels, which can achieve the designed absorption coefficient with a shorter channel overall. Introducing channels with a nonuniform cross section changes the period of the surface acoustic impedance, which has a significant impact on the dominant operating frequencies. In this paper, we give the relation between the absorption peak position and the geometric parameters, which can be used to design DNUCS channels with a specific operating frequency. Furthermore, multiple nonuniform cross-section channels can be studied in the same way. Based on the above theory, we reduce the operating absorption frequency range of a new type of Fabry–Pérot absorbers to a lower regime in a constant volume. Our theoretical framework may be important in designing absorption metasurfaces and for further research.

Acoustic Metamaterials for Low-Frequency Noise Reduction Based on Parallel Connection of Multiple Spiral Chambers

“…The most effective strategy to broaden the sound absorption bandwidth is to combine the various resonant response units [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. It is difficult to accurately modulate the resonance frequencies of multiple units in the membrane AM due to the difficulty in controlling the membrane tension, so it is seldom used in low-frequency broadband noise control.…”

“…The advantage of an FP chamber is that it can make sound waves propagate along a coiled path through crimping, folding, and other chamber forms. Researchers have carried out related research on the FP AM [ 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. By using the coiled-up method, Zhang et al [ 29 ] proposed an absorber based on six coiled FP channels, which achieved perfect absorption at 100–200 Hz and the requirement of deep-subwavelength thickness (0.07 λ ) can still be satisfied.…”

“…By using the coiled-up method, Zhang et al [ 29 ] proposed an absorber based on six coiled FP channels, which achieved perfect absorption at 100–200 Hz and the requirement of deep-subwavelength thickness (0.07 λ ) can still be satisfied. Based on the theory of double non-uniform cross-section channels with different widths, a double non-uniform cross section proposed by Han et al [ 31 ] was applied to AM with the 16 FP channels, which effectively reduced the lower cut-off frequency in the sound-absorbing structure. The flexible designs greatly reduce the 1/4 wavelength λ scale required for FP channel resonance by using a crimped form and combining FP channels with different resonant frequencies to achieve wide sound absorption, with accurate design and layout.…”

Experimental study of an tunable acoustic phase-shifter

“…Acoustic metasurfaces are a topical issue in modern research since they allow for efficient refraction [1], reflection [2], focusing [3], absorption [4] and change of the wave front [5] of acoustic waves. A metasurface is usually made up of a set of cells that allow for changing the phase of a propagated wave by a specified value, e.g., from a discrete set nπ/4, where n = 0−7.…”

Экспериментальное Исследование Перестраиваемого Акустического Фазовращателя

“…Акустические метаповерхности являются актуальной темой современных исследований, так как они позволяют эффективно осуществлять преломление [1], отражение [2], фокусировку [3], поглощение [4] и изменение волнового фронта [5] акустических волн. Основой метаповерхности обычно является набор ячеек, позволяющих изменять фазу прошедшей волны на заданную величину, например, из дискретного набора nπ/4, где n = 0−7.…”