Helical normal waves near a cylindrical cavity in an elastic medium

Tyutekin, V. V.; Бойко, А. І.

doi:10.1134/s106377101002003x

Cited by 10 publications

(4 citation statements)

References 1 publication

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“…The black dotted line shows the absorption performance from the homogeneous rubber without voids. Due to the monopole resonance of the single-layer void array [2,23,31,32], the hump absorption will occur at 500 Hz under ordinary pressure (0.1 MPa). Affected absorption performance is shown in detail in Figure 5b; here, the red globes correspond to the located frequency of the first absorption crest value, while the navy blue pentagrams refer to the absorption amplitude.…”

Section: Effect Of the Geometric Deformation On Absorption Performanc...mentioning

confidence: 99%

Investigation on Low-Frequency and Broadband Sound Absorption of the Compact Anechoic Coating Considering Hydrostatic Pressure

Fang,

Pan,

Zhang

et al. 2024

JMSE

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The anechoic coating capable of absorbing sound energy in low frequencies within broadband is essential to conceal underwater vehicles. However, the geometric deformation and modification of mechanical parameters under hydrostatic pressure affect the prediction of absorption performance in deep water environments. An anechoic coating embedded with tandem resonant voids is proposed in this work to achieve quasi-perfect low-frequency and broadband absorption. The analytical method based on the effective medium approach and numerical simulation are performed to estimate the effects of hydrostatic pressure on sound absorption. When additionally considering the dynamic mechanical parameters of the compressed viscoelastic medium, the original absorption humps in low frequencies are inclined to higher band, accompanied by the expanded absorption bandwidth. Then, the tandem coating specimen is measured in a water-filled impedance tube. The experimental spectra are consistent with the analytical and numerical results under various hydrostatic pressures, demonstrating the efficient absorption (α > 0.7) in broadband low frequencies via ordinary pressure. At the same time, the absorption spectrum under higher hydrostatic pressures is also verified in the tube. Consequently, this work paves the way for a broadband low-frequency underwater absorber design and provides an efficient method to characterize the low-frequency and broadband absorption from the coupled resonant coatings in deep water environments.

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Section: Effect Of the Geometric Deformation On Absorption Performanc...mentioning

confidence: 99%

Investigation on Low-Frequency and Broadband Sound Absorption of the Compact Anechoic Coating Considering Hydrostatic Pressure

Fang,

Pan,

Zhang

et al. 2024

JMSE

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show abstract

“…Take the discontinuous isolation barrier that is applied for a point vibration source as an example. ere are three different approaches for a wave to pass through an isolation barrier: diffraction [20], transmission [21], and scattering [22]. Moreover, the isolation barrier can also reflect the wave [23].…”

Section: Correlation Theory Test Condition and Proceduresmentioning

confidence: 99%

Vibration Isolation Mechanism of Concrete Piles for Rayleigh Waves on Sand Foundations

Liu¹,

Feng²,

Zhang³

et al. 2018

Shock and Vibration

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To study the propagation characteristics of Rayleigh waves and the isolation mechanism of a single-row of piles by isolation effects, in this paper we draw a two-dimensional contour map of ζ (normalized acceleration amplitude relative to a measure close at the vibration source) using a vibration test carried out on a sand foundation. In this experiment, we study, in addition to the free field and the single pile cases, settings with two and three piles. The result shows that the vibration caused by the point source in the free field excites Rayleigh waves in a radial direction along the surface of the foundation. Meanwhile, the vibrations of the points along the propagation path on the surface of the foundation are gradually weakened. There is a steady transition when the ζ drops to 0.6 and a placid decline when ζ decreases to less than 0.25. The vibration-shielded region, the strengthened region, and the strengthened strips will appear on the surface of the foundation. The vibration-shielded region is located behind the piles, and the region presents a trumpet-shaped area that takes the pile as the vertex. Increasing the quantity of piles contributes to increasing the vibration isolation effect, not only that involving the degree of isolation but also for the area of the shielded area. The vibration-strengthened regions include the diffraction regions at the pile corners on both sides of the single-row of piles and the scattering region at the gaps of the piles. In addition, the composite regions are located among the vibration source and the scattering and diffraction-strengthened regions. Increasing the number of piles has little influence on the scattering and diffraction-strengthened regions but can significantly enhance the vibrations of the composite regions. In general, the vibration-strengthened strips are connected with the scattering-strengthened regions. However, in the test of a single pile, the pile is connected to the diffraction-strengthened regions near its two anterior angles.

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“…Extensions of the Pochhammer-Chree waves to helical waves (longitudinal axially symmetric modes) that relate to non-integer coefficients at the angle coordinate in the corresponding potentials were analyzed [24][25][26].…”

Section: Introductionmentioning

confidence: 99%