Sound Propagation in Plates and Rods of Elastomeric Materials

1959 ◽  
Vol 32 (1) ◽  
pp. 21-39
Author(s):  
H. J. Naake ◽  
K. Tamm
Keyword(s):  
Elastic Waves ◽  
Sound Propagation ◽  
Dispersion Curves ◽  
Low Frequencies ◽  
Compressional Waves ◽  
High Frequencies ◽  
High Attenuation ◽  
Elastomeric Materials ◽  
Propagation Of Elastic Waves ◽  
Phase Velocity And Attenuation

Abstract The known results for the propagation of sound in plates with Poisson's constant σ=0.5 (liquids) and σ=0.35 (aluminum) are completed by dispersion curves with σ=0.47 (rubber). The dispersion curves are easily understandable because of the large difference between the velocities of transverse and longitudinal waves occurring at this value of σ. Measurements of the propagation of elastic waves in rods of rubber with square cross section in the frequency range 0.1 to 300 kc/s are reported. The amplitude is measured as a function of distance by partly submerging the rod into a waterfilled vessel within which a hydrophone is arranged. The results with respect to phase velocity and attenuation can be explained in terms of the propagation of extensional waves at low frequencies and compressional waves at high frequencies separated by a range with high attenuation.

A theory of compressional wave attenuation in noncohesive sediments

Geophysics ◽  
1985 ◽  
Vol 50 (8) ◽  
pp. 1311-1317 ◽  
Author(s):  
C. McCann ◽  
D. M. McCann
Keyword(s):  
Wave Attenuation ◽  
Compressional Wave ◽  
Solid Particles ◽  
Biot’S Theory ◽  
Attenuation Coefficients ◽  
Low Frequencies ◽  
Biot's Theory ◽  
Compressional Waves ◽  
High Frequencies ◽  
Water Saturated

Published reviews indicate that attenuation coefficients of compressional waves in noncohesive, water‐saturated sediments vary linearly with frequency. Biot’s theory, which accounts for attenuation in terms of the viscous interaction between the solid particles and pore fluid, predicts in its presently published form variation proportional to [Formula: see text] at low frequencies and [Formula: see text] at high frequencies. A modification of Biot’s theory which incorporates a distribution of pore sizes is presented and shown to give excellent agreement with new and published attenuation data in the frequency range 10 kHz to 2.25 MHz. In particular, a linear variation of attenuation with frequency is predicted in that range.

Leaking modes in a crust with a surface layer

1971 ◽  
Vol 61 (1) ◽  
pp. 93-107 ◽  
Author(s):  
Anton M. Dainty
Keyword(s):  
Dispersion Curves ◽  
Source Depth ◽  
Low Velocity ◽  
Surface Source ◽  
Low Frequencies ◽  
Near Surface ◽  
High Frequencies ◽  
Explosive Source ◽  
Low Velocity Layer ◽  
Velocity Layer

abstract Dispersion curves, attenuation functions and excitation functions for an explosive source at depth for four different models of the crust are presented for the leaking modes P(+, −), P(−, +) and π1(−, +). One of the objectives of the calculations was to determine the effect of a surface, low-velocity layer on the dispersion curves and attenuation functions. For the mode P(+, −) (the fundamental leaking mode), the differences are slight, while more pronounced differences are found for the other modes. The variation of the excitation function with depth of the source has been studied. For the modes P(+, −), P(−, +) low frequencies are enhanced and high frequencies suppressed for one of the models as the source depth increases. According to this study, a source deep in the crust should be a more efficient exciter of the mode P(+, −) (the most commonly seen mode) than a near-surface source.

Diffraction of elastic waves by a rigid circular disc

1968 ◽  
Vol 64 (1) ◽  
pp. 237-247 ◽  
Author(s):  
A. K. Mal ◽  
D. D. Ang ◽  
L. Knopoff
Keyword(s):  
Rate Of Convergence ◽  
Integral Equations ◽  
Elastic Waves ◽  
Contraction Mapping ◽  
Normal Incidence ◽  
Iteration Procedure ◽  
Circular Disc ◽  
Low Frequencies ◽  
Compressional Waves ◽  
Diffraction Of Elastic Waves

AbstractThe problem of the diffraction of axisymmetric harmonic elastic waves by a rigid circular disc is reduced to finding the solution of a pair of integral equations of the second kind suitable for iteration at low frequencies. Using the principle of contraction mapping, the rate of convergence of the iteration procedure is discussed and the error caused by stopping at any particular stage estimated. Detailed calculations are given for plane compressional waves at normal incidence.

scholarly journals Study on Transmission Characteristics of Vertical Rail Vibrations in Ballast Track

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Xi Sheng ◽  
Caiyou Zhao ◽  
Ping Wang ◽  
Dongya Liu
Keyword(s):  
Transmission Rate ◽  
Spectral Element ◽  
Transmission Characteristics ◽  
Low Frequencies ◽  
High Frequencies ◽  
Vibration Absorption ◽  
High Attenuation ◽  
Antiresonance Frequency ◽  
Ballast Track ◽  
Track Substructure

A plane half-track model and a periodic track-substructure model are established. The spectral element method and spectral transfer matrix method are developed and applied to investigate the track decay rate (TDR) and transmission rate (TR) of the vertical rail vibrations, which can reflect the transmission characteristics in the longitudinal and downward directions, respectively. Furthermore, the effects of different track parameters on TDR and TR are investigated. The results show that the antiresonance frequency of the rail and the out-of-phase resonance frequency of the rail and sleeper form the boundary frequencies of the high-attenuation zone for longwise vibration transmission, where the vibration absorption of the sleeper is significant. The downward transmissibility of vertical rail vibrations is greatest around the antiresonance frequency of the rail. Vertical rail vibrations are primarily transmitted in the downward direction at low frequencies, while they are mainly transmitted along the rail at high frequencies. Stiffer rail pads can make more vibrations transmitted downwards to the sleeper above the antiresonance frequency of the rail, while the changes of other track parameters have different effects on the transmission characteristics. Additionally, a field measurement is performed for verification, and the simulations are well consistent with measurements.

scholarly journals Acoustic cavities in 2D heterostructures

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Maxim K. Zalalutdinov ◽  
Jeremy T. Robinson ◽  
Jose J. Fonseca ◽  
Samuel W. LaGasse ◽  
Tribhuwan Pandey ◽  
...  
Keyword(s):  
Sound Propagation ◽  
Phonon Scattering ◽  
Frequency Comb ◽  
Material Interfaces ◽  
Low Frequencies ◽  
Strongly Coupled ◽  
Propagation Analysis ◽  
Acoustic Cavities ◽  
Ab Initio Approach ◽  
Spatiotemporal Response

AbstractTwo-dimensional (2D) materials offer unique opportunities in engineering the ultrafast spatiotemporal response of composite nanomechanical structures. In this work, we report on high frequency, high quality factor (Q) 2D acoustic cavities operating in the 50–600 GHz frequency (f) range with f × Q up to 1 × 1014. Monolayer steps and material interfaces expand cavity functionality, as demonstrated by building adjacent cavities that are isolated or strongly-coupled, as well as a frequency comb generator in MoS2/h-BN systems. Energy dissipation measurements in 2D cavities are compared with attenuation derived from phonon-phonon scattering rates calculated using a fully microscopic ab initio approach. Phonon lifetime calculations extended to low frequencies (<1 THz) and combined with sound propagation analysis in ultrathin plates provide a framework for designing acoustic cavities that approach their fundamental performance limit. These results provide a pathway for developing platforms employing phonon-based signal processing and for exploring the quantum nature of phonons.

Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam

2015 ◽  
Vol 804 ◽  
pp. 25-29 ◽  
Author(s):  
Wanlop Harnnarongchai ◽  
Kantima Chaochanchaikul
Keyword(s):  
Natural Rubber ◽  
Cell Size ◽  
Cell Morphology ◽  
Foam Cell ◽  
Adsorption Coefficient ◽  
Low Frequencies ◽  
Potassium Oleate ◽  
High Frequencies ◽  
Blowing Agent ◽  
Open Cell Foam

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.

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