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1

Improving Sound Insulation in Low Frequencies by a Three-Component Cladding Acoustic Metamaterial Panel

Tan Na, Yan Xiaowei, Liu Bingfei

Archives of Acoustics

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2024

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Vol. 49, nr 2

267--276

EN

In this paper, a three-component cladding acoustic metamaterial panel with good sound insulation effect in the low-frequency range is proposed. The sound transmission loss of metamaterial panels under different structural configurations and different material parameters is investigated by combining finite element simulation calculations with experimental research. The results show that the closer the center of gravity of the scatterer is to the substrate, the better the stability of the resonance unit, the wider the range of effective sound isolation frequencies, and the higher the degree of normalization. The filling rate of the scatterer is maintained at about 0.5 to obtain a better sound insulation effect. At the same time, choosing lower density materials for the substrate and metal materials with high density and high modulus of elasticity for the scatterer can maximally widen the bandgap and allows for low-frequency sound insulation below 600 Hz. This approach improves the low-frequency sound insulation efficiency of acoustic metamaterials. The results provide important explanations and references for a deeper understanding of the sound insulation mechanism and the effects of different parameters on sound insulation.

2

Improvement of Sound Insulation Through Double-Panel Structure by Using Hybrid Local Resonator Array

Ri Kyong-Su, Kim Myong-Jin, Son-U Se-Hyon

Archives of Acoustics

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2023

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Vol. 48, No. 1

63--70

EN

In this paper, we present one approach to improve the soundproofing performance of the double-panel structure (DPS) in the entire audible frequencies, in which two kinds of local resonances, the breathing-type resonance and the Helmholtz resonance, are combined. The thin ring resonator row and slit-type resonator (Helmholtz resonator) row are inserted between two panels of DPS together. Overlapping of the band gaps due to the individual resonances gives a wide and high band gap of sound transmission in the low frequency range. At the same time, the Bragg-type band gap is created by the structural periodicity of the scatterers in the high audible frequency range. In addition, the number of scatterer rows and the filling factor are investigated with regard to the sound insulation of DPS with sonic crystals (SCs). Consequently, the hybrid SC has the potential of increasing the soundproofing performance of DPS in the audible frequency range above 1 kHz by about 15 dB on average compared to DPS filled only with glass wool between two panels, while decreasing the total thickness and mass compared to the counterparts with the other type of local resonant sonic crystal.

3

A Honeycomb Based Graded Metamaterial Muffler with Broadband Sound Attenuation and Load Bearing Performances

Li Gen, Chen Yan, He Huan

Archives of Acoustics

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2022

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Vol. 47, No. 2

213--221

EN

A challenge for developing acoustic metamaterials (AMMs) is considering the application of broadband muffling and load bearing capacity simultaneously. In this paper, a honeycomb based graded AMM muffler is proposed, which can widen the attenuation band and improve the structural stiffness without any external device by means of integrated design. Firstly, the acoustic and mechanical characteristics of the muffler unit cell are theoretically and numerically studied, and the graded muffler is designed based on these characteristics. The numerical results show that the graded muffler widens the attenuation bandwidth of the unit cell, and the simulation also shows that the graded muffler has greater stiffness than the uniform one. The stiffness driven muffler provides new possibilities for the design of advanced metamaterial with simultaneous sound insulation and load bearing performances.

4

Statistical Optimization of Underwater Lower-Frequency Sound Insulation for Locally Resonant Sonic Material Using Genetic Algorithm

Yuan Bo, Chen Yong, Tan Bilian, Li Bo

Archives of Acoustics

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2019

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Vol. 44, No. 2

365--374

EN

The locally resonant sonic material (LRSM) is an artificial metamaterial that can block underwater sound. The low-frequency insulation performance of LRSM can be enhanced by coupling local resonance and Bragg scattering effects. However, such method is hard to be experimentally proven as the Best optimizing method. Hence, this paper proposes a statistical optimization method, which first finds a group of optimal solutions of an object function by utilizing genetic algorithm multiple times, and then analyzes the distribution of the fitness and the Euclidean distance of the obtained solutions, in order to verify whether the result is the global optimum. By using this method, we obtain the global optimal solution of the low-frequency insulation of LRSM. By varying parameters of the optimum, it can be found that the optimized insulation performance of the LRSM is contributed by the coupling of local resonance with Bragg scattering effect, as well as a distinct impedance mismatch between the matrix of LRSM and the surrounding water. This indicates coupling different effects with impedance mismatches is the Best method to enhance the low-frequency insulation performance of LRSM.