Local resonance – Helmholtz lattices with simultaneous solid-borne elastic waves and air-borne sound waves attenuation performance

In non-isotropic single crystals the normals to the wavefronts of elastic waves are not colinear with the vectors representing either the energy flow or the particle displacement. Calculations have been carried out on the propagation characteristics of sound waves in two particular trigonal crystals, α-quartz and sapphire.The development of the eigenvalue equation for the velocity and the formulae for the components of the displacement and energy-flow vectors are summarized. The assumption that the wave has a plane wavefront normal to a given direction leads to three solutions, one representing a quasi-longitudinal wave and the other two representing quasi-transverse waves. The velocities of propagation, directions of displacement, and directions of energy flow for the three waves have been calculated for many orientations of the wave normal. Detailed results for propagation near one of the pure-mode axes are presented.

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Measurement of Acoustic Emission Signals: Influence of the Couplant

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.347.375 ◽

2007 ◽

Vol 347 ◽

pp. 375-380 ◽

Cited By ~ 2

Author(s):

Alessandro Fasana ◽

Luigi Garibaldi

Keyword(s):

Acoustic Emission ◽

Elastic Waves ◽

Pulse Generator ◽

Pressure Vessels ◽

Sound Waves ◽

Local Distribution ◽

Frequency Range ◽

Typical Application ◽

Short Summary ◽

Non Destructive

The acoustic emission (AE) technique, whose modern roots are found in the early 50’s, analyses the elastic waves generated into solid materials in a frequency range usually well above the human ears limit. AE are sound waves emitted when abrupt variations occur in the local distribution of strain in a medium. These variations are generally associated with, for example, the growth of fractures, phase transformations and corrosion under various loading conditions. This is why the AE technique can be applied as a non destructive and passive tool in condition monitoring of structures, a typical application being the pressure vessels and piping field. In this paper, after a short summary on wave propagation, the AE is simulated by a pulse generator, acting on a bar and a plate. The aim is to highlight the effects of the sensors positioning on some of the parameters frequently adopted to describe the AE activity, e.g. its amplitude and strength.

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Elastic waves propagation in thin plate metamaterials and evidence of low frequency pseudo and local resonance bandgaps

Physics Letters A ◽

10.1016/j.physleta.2019.05.039 ◽

2019 ◽

Vol 383 (23) ◽

pp. 2789-2796 ◽

Cited By ~ 13

Author(s):

Muhammad ◽

C.W. Lim

Keyword(s):

Thin Plate ◽

Elastic Waves ◽

Low Frequency ◽

Local Resonance ◽

Waves Propagation

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Lantern Slide Illustrating Sound Waves

Scientific American ◽

10.1038/scientificamerican06231894-395 ◽

1894 ◽

Vol 70 (25) ◽

pp. 395-395

Author(s):

M. Hopkins

Keyword(s):

Sound Waves ◽

Lantern Slide

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The Secret Telephone, Are Sound Waves ever Visible?

Scientific American ◽

10.1038/scientificamerican12061919-555 ◽

1919 ◽

Vol 121 (23) ◽

pp. 555-555

Author(s):

F. Honore

Keyword(s):

Sound Waves

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Remarks on nonlinear elastic waves with null conditions

ESAIM Control Optimisation and Calculus of Variations ◽

10.1051/cocv/2020039 ◽

2020 ◽

Vol 26 ◽

pp. 121

Author(s):

Dongbing Zha ◽

Weimin Peng

Keyword(s):

Initial Data ◽

Global Existence ◽

Elastic Waves ◽

Wave Equations ◽

Alternative Proof ◽

Classical Solutions ◽

Small Initial Data ◽

Hyperelastic Materials ◽

Variational Structure ◽

Nonlinear Elastic

For the Cauchy problem of nonlinear elastic wave equations for 3D isotropic, homogeneous and hyperelastic materials with null conditions, global existence of classical solutions with small initial data was proved in R. Agemi (Invent. Math. 142 (2000) 225–250) and T. C. Sideris (Ann. Math. 151 (2000) 849–874) independently. In this paper, we will give some remarks and an alternative proof for it. First, we give the explicit variational structure of nonlinear elastic waves. Thus we can identify whether materials satisfy the null condition by checking the stored energy function directly. Furthermore, by some careful analyses on the nonlinear structure, we show that the Helmholtz projection, which is usually considered to be ill-suited for nonlinear analysis, can be in fact used to show the global existence result. We also improve the amount of Sobolev regularity of initial data, which seems optimal in the framework of classical solutions.

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