Ultralow-frequency broadband characteristics of stepwise radial metamaterials

Li, Lixia; He, Weitao; Jia, Qi; Tong, Zhixue; Liu, Haixia; Li, Pengguo; Li, Ling

doi:10.1063/5.0096667

Cited by 5 publications

(5 citation statements)

References 44 publications

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“…It is worth mentioning that even though the above calculation of the energy band curve of the SR-ABH is based on the ideal structure with the infinite period, it is unrealistic to apply the wireless period in practice. Thus, it is necessary to use the elastic wave transmission properties of the finite period structure to verify the shielding characteristics of the designed structure with respect to the elastic wave [24]. In particular, the displacement excitation u input at the SR-ABH boundary can be assumed, and the displacement output u output can be recorded at the truncation of the SR-ABH.…”

Section: Resultsmentioning

confidence: 99%

“…Gao et al [23] designed a composite radial metamaterial whose band gap characteristics exceeded traditional metamaterials due to the coupling effect inside the proposed structure. Li et al [24] developed a stepped radial metamaterial, which opened the local resonance and Bragg scattering band gap by introducing a gradient array, enhancing the ultra-low frequency broadband characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Low-frequency broadband characteristics of stepwise radial acoustical black holes

Li,

Bai,

Yang

et al. 2024

Phys. Scr.

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In this paper, a stepped radial acoustic black hole (SR-ABH) structure formed by the stepwise arrangement of two-dimensional radial acoustic black holes is proposed. The finite element method is used to calculate the energy band and frequency response curve of SR-ABH, and it was found that the low-frequency bandgap at 0~2000Hz accounted for 83.4%, which is 7.6 times wider than the ABH arranged radially horizontally(HR-ABH). On the basis of modal analysis at special points, the introduction of gradient arrays into radial acoustic black holes is determined, which reduces the cut-off frequency of acoustic black holes and forms a low-frequency broadband coupling of local resonance effect and acoustic black hole effect. In addition, the mechanism of the influence of geometric parameters on the bandgap was explored. The results indicate that as the step height increases, the coupling relationship between local resonance effect and acoustic black hole effect shows a trend of first strengthening and then weakening, thereby affecting the movement of low-frequency bandgap. The proposal of this structure provides ideas for reducing the high cut-off frequency expansion of acoustic black holes.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Low-frequency broadband characteristics of stepwise radial acoustical black holes

Li,

Bai,

Yang

et al. 2024

Phys. Scr.

Self Cite

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“…( 6) in Eqs. ( 7) and (8). As substantiated in [7] and [13], the resulting determinant is a fourth-order polynomial in Λ:…”

Section: Polar Coordinatesmentioning

confidence: 86%

“…In all these cases, radial periodicity can be utilised to reduce vibration transmission, and the periodic inserts can function as a vibroacoustic filter when the dominant excitation frequency falls within a stopband. The use of radial periodicity for vibration reduction was, for example, investigated in [8] where it was shown that a periodic structure, arranged in a stepwise shape along the radial direction, was able to attenuate vibration due to its low-frequency bandgap characteristics. Radial periodic structures have also been shown to be effective in protecting constructions from seismic waves; as an example, in [9], a new type of seismic metamaterial with radial periodicity was studied, demonstrating its effectiveness, compared to traditional seismic metamaterials, in attenuating seismic Lamb and surface waves.…”

Section: Introductionmentioning

confidence: 99%

Numerical Analysis of Vibration Attenuation and Bandgaps in Radially Periodic Plates

Manconi

Hvatov

Sorokin

2023

J. Vib. Eng. Technol.

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Objective Periodic configuration of mechanical and civil structures has shown great potential for noise and vibration reduction. However, the use of Cartesian coordinates in studying periodicity effects in elastic structures overlooks the benefits of radially periodic configurations when dealing with wave propagation in large flexible plates disturbed by a small source area. This paper presents an easy-to-use numerical approach to predicting bandgap characteristics in polar coordinates. Methodology To demonstrate the vibration-attenuation effect, we consider a circular radially periodic plate model. We use an adapted Wave Finite-Element method in numerical experiments to demonstrate the existence of the attenuation effect. To verify the numerical results, we apply an adapted Floquet theory to polar coordinates. Results and Conclusions Our findings indicate that theoretical and numerical results are in excellent agreement considering a new parameter that introduces the distance from the origin. The adapted Wave Finite-Element approach and Floquet theory presented here demonstrate their potential to model more complex structures in polar coordinates.

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“…In the case of a finite-period structure, it is necessary to calculate the transmittance to describe its transmission characteristics. The transmittance is determined by applying acceleration excitation along the Y-direction at one end of the finite-period structure and simultaneously recording the acceleration response generated at the other end [45]. The transmittance is calculated as follows:…”

Section: Theoretical Modeling For the Vibroacoustic Characteristicmentioning

confidence: 99%

A cylindrical shell comprising multifunctional metamaterial cores with ultra-low frequency vibroacoustic reduction and mechanical performances

Jia,

Yu,

Fang

et al. 2024

Phys. Scr.

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Deep-sea submersible is an important part of oceanic equipment, where special operating environment must require the outer material to have multifunctional properties such as load-bearing, buckling, and vibroacoustic suppression. Here, we proposed a novel metamaterial with excellent mechanical and ultra-low frequency vibroacoustic characteristics as a core material for cylindrical shells used in deep-sea submersibles. Compared to honeycomb materials, the proposed metamaterial utilized the design principles of local resonance theory, incorporating a subwavelength structure periodically embedded within the porous honeycomb structure. This configuration was expected to result in superior static and dynamic properties. Then, we systematically discussed the mechanical and vibroacoustic performance of sandwich cylindrical shells with metamaterial cores, characterized by positive or negative Poisson's ratios, to explore their potential for engineering applications in submerged pressure-resistant structures. The respective unit cells were designed to have equivalent load-bearing capabilities, and simulations were conducted to analyze the physical characteristics related to pressure resistance, buckling, and wave reduction. The results indicated that, compared to conventional honeycomb structures, the metamaterials based on PMMA could safely withstand hydrostatic pressures of nearly 7 MPa, resulting in nearly a twofold increase in structural strength. Additionally, the proposed metamaterials could open bandgaps in an ultra-low frequency range (with the normalized frequency Ω as low as 0.013) and an ultra-wide frequency range (with the bandwidth ratio as high as 83.50%), attributable to the coupling effect of traveling waves and subwavelength units. It is worth noting that the robustness and hydrostatic pressure insensitivity of the metamaterial were demonstrated in the studied hydrostatic pressure range of 0.1 MPa to 5 MPa. This work verified the feasibility of coupling the design between local resonance theory and porous structures, and provided guidance for the multifunctional design of sandwich cylindrical shells.

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Ultralow-frequency broadband characteristics of stepwise radial metamaterials

Cited by 5 publications

References 44 publications

Low-frequency broadband characteristics of stepwise radial acoustical black holes

Low-frequency broadband characteristics of stepwise radial acoustical black holes

Numerical Analysis of Vibration Attenuation and Bandgaps in Radially Periodic Plates

A cylindrical shell comprising multifunctional metamaterial cores with ultra-low frequency vibroacoustic reduction and mechanical performances

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