Controlling sound transmission by space-coiling fractal acoustic metamaterials with broadband on the subwavelength scale

Xiang, Lei; Wang, Gongxian; Zhu, Chao

doi:10.1016/j.apacoust.2021.108585

Cited by 21 publications

(9 citation statements)

References 48 publications

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“…The multiband acoustic suppression behaviors at the deeply sub-wavelength scale were found. Xiang et al 34 developed a space-coiling acoustic metamaterial with fractal geometry, and the dispersion and transmission characteristics were studied. The results demonstrated that the structure has outstanding performance in low-frequency sound insulation.…”

Section: Introductionmentioning

confidence: 99%

Design of a broadband metasurface sound absorber based on Hilbert fractal

Zhang

Zhao

2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this paper, a new fractal-based broadband metasurface absorber is developed, which is based on the excellent space-filling ability of the Hilbert fractal. Each unit cell in absorber consists of a micro perforated panel (MPP) and a coplanar coiled cavity. In order to gain a deep insight into the sound absorption mechanism and perform a rapid design, a theoretical model for analyzing the sound absorption characteristics of the unit cell is established, in which the Fok function is used to account for the coupling effect between holes. Afterward, the absorption mechanism as well as the effects of parameter variations on absorption characteristics are investigated. To increase the space utilization, each unit cell is arranged in space according to the Hilbert fractal curve. Consequently, a metasurface absorber with 6 detuned unit cells is constructed. The multiple resonant cavities with dissimilar lengths can provide peak absorptions at multiple frequencies, thereby broadening the attenuation frequency range. Finally, the absorption performance of the designed absorber is obtained by theoretical calculations, finite element (FEM) simulations and experimental measurements, respectively. The experimental results show that a continuous absorption spectrum is achieved in the range of 855–1359 Hz with absorption coefficient above 0.8 under a deeply sub-wavelength thickness (22.2 mm). This study provides an effective way for the design of a space-limited broadband absorber. With the advantages of ultrathin thickness, broadband, and compactness, the developed fractal-based metasurface absorber has great potential in the field of noise reduction.

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Section: Introductionmentioning

confidence: 99%

Design of a broadband metasurface sound absorber based on Hilbert fractal

Zhang

Zhao

2023

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…The research of acoustic metamaterials was initially inspired by the analogy of electromagnetic metamaterials [1][2][3][4]. On the basis of research on electromagnetic metamaterials, some scholars have turned their attention to the research of acoustic metamaterials with single and double negative properties and zero refractive index, to realize the supernormal acoustic wave transmission characteristics such as subwavelength imaging [5][6][7], acoustic tunneling [8][9][10], acoustic prism [11][12][13] and target stealth [14][15][16][17]. Acoustic metamaterials can exhibit double negative characteristics, with negative bulk modulus achievable through monopole resonance and negative mass density achievable through dipole resonance.…”

Section: Introductionmentioning

confidence: 99%

A football-like acoustic metamaterial with near-zero refractive index and broadband ventilated sound insulation

Wang,

Chen,

Liu

2023

J. Phys. D: Appl. Phys.

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Acoustic metamaterial with negative or near-zero refractive index exhibits extraordinary acoustic transmission characteristics, including acoustic total reflection, acoustic stealth and acoustic tunneling. Based on the coiled-up space structure, a football like near-zero refractive index acoustic metamaterial (FNZIM) was proposed. The result reveals the formation of two transmission peaks at 1270 Hz and 2300 Hz from the equivalent parameters by using the transfer matrix method. The first peak exhibits excellent air impedance matching, while the second peak arising from the metamaterial’s near-zero refractive index. We then constructed an acoustic prism using 15 cells of FNZIM and calculated the dispersion curve, revealing that the near-zero refractive index supernormal transmission of metamaterials is attributable to multimode degeneracy. Furthermore, we find that the positions of the transmission peaks and transmission loss can be adjusted by appropriately altering the structural parameters. Finally, we tested two groups of samples by using impedance tube four-channel to verify the accuracy of the simulation and the validity of insulation performance of FNZIM. The broadband ventilation sound insulation coupled structure is constructed, and the average sound insulation performance of this structure is more than 25 dB in the range of 1140–2210 Hz.

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“…[13][14][15][16][17][18] A significant challenge that has yet to be achieved in both theoretical models and experimental validation is to achieve long beam projection of lowfrequency-band acoustic waves with long wavelengths, similar to active parameter control, through the smallest possible metastructures. [19][20][21][22][23] This letter introduces a novel theoretical method for designing a two-dimensional acoustic metalens by means of multiple scattering theory. The proposed approach is validated through both finite element simulations and experimental verification.…”

mentioning

confidence: 99%

“…In Ref. 22, a lens longer than 100 cm was constructed with units of 7.8 cm. In this study, the lens was designed to be compact and efficient.…”

mentioning

confidence: 99%

Novel phononic-crystal-arrayed acoustic metalens for long beam focusing in multi-band

Zhang

Tao

Wang

et al. 2023

Appl. Phys. Express

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We propose a multi-band acoustic metalen that achieves 18-26λ long-range beam focusing and narrow full width at half maximum (FWHM) of 4-5λ across multiple frequency bands, utilizing principles of multiple scattering theory. The metalens sample was meticulously fabricated using quadrilateral lattice scatterers in the cross-section, and its experimental acoustic field tests showed focused sound beams with a length of 0.78 - 1.07 m falling within the frequency bands of 5800 - 6100 Hz, 8500 - 8700 Hz, and 9700 - 9900 Hz. This study holds potential applications in acoustic directional projection, signal enhancement, and acoustic power collection.

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Controlling sound transmission by space-coiling fractal acoustic metamaterials with broadband on the subwavelength scale

Cited by 21 publications

References 48 publications

Design of a broadband metasurface sound absorber based on Hilbert fractal

Design of a broadband metasurface sound absorber based on Hilbert fractal

A football-like acoustic metamaterial with near-zero refractive index and broadband ventilated sound insulation

Novel phononic-crystal-arrayed acoustic metalens for long beam focusing in multi-band

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