scholarly journals Balance of energy between scattered and reflected waves resulting from an axial surface wave incident on a discontinuity of a fluid‐loaded cylindrical shell

1994 ◽  
Vol 96 (5) ◽  
pp. 3340-3340
Author(s):  
Steven L. Means
Keyword(s):  
Cylindrical Shell ◽  
Surface Wave ◽  
Wave Incident ◽  
Reflected Waves ◽  
Axial Surface

scholarly journals A Practical Guide to Source and Receiver Locations for Surface Wave Transmission Measurements across a Surface-Breaking Crack in Plate Structures

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3793
Author(s):  
Janghwan Kim ◽  
Seong-Hoon Kee ◽  
Jin-Wook Lee ◽  
Ma. Doreen Candelaria
Keyword(s):  
Surface Wave ◽  
Wave Transmission ◽  
Laser Vibrometer ◽  
Plate Structures ◽  
Reflected Waves ◽  
Practical Guide ◽  
Practical Guidelines ◽  
Transmission Measurements ◽  
Simulation Results ◽  
Surface Breaking Crack

The main objectives of this study are to investigate the interference of multiple bottom reflected waves in the surface wave transmission (SWT) measurements in a plate and to propose a practical guide to source-and-receiver locations to obtain reliable and consistent SWT measurements in a plate. For these purposes, a series of numerical simulations, such as finite element modelling (FEM), are performed to investigate the variation of transmission coefficient of surface waves across a surface-breaking crack in various source-to-receiver configurations in plates. Main variables in this study include the crack depths (0, 10, 20, 30, 40 and 50 mm), plate thicknesses (150, 200, 300, 400 and 800 mm), source-to-crack distances (100, 150, 200, 250 and 300 mm) and receiver-to-crack distances. The validity of numerical simulation results was verified by comparison with results from experiments using Plexiglas specimens using two types of noncontact sensors (laser vibrometer and air-coupled sensor) in the laboratory. Based on simulation and experimental results in this study, practical guidelines for sensor-to-receiver locations are proposed to reduce the effects of the interference of bottom reflected waves on the SWT measurements across a surface-breaking crack in a plate. The findings in this study will help obtain reliable and consistent SWT measurements across a surface-breaking crack in plate-like structures.

The behaviour of elastic surface waves polarized in a plane of material symmetry. I. Addendum

1991 ◽  
Vol 433 (1889) ◽  
pp. 699-710 ◽  
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Plane Waves ◽  
Transversely Isotropic ◽  
Point Of View ◽  
Reference Plane ◽  
Material Symmetry ◽  
Reflected Waves ◽  
Inhomogeneous Plane ◽  
Symmetric Surface

This addition to a recent paper by Chadwick ( Proc. R. Soc. Lond . A 430, 213 (1990); hereafter referred to as part I) has been prompted mainly by the discovery of secluded supersonic surface waves propagating in configurations of transversely isotropic elastic media in which the reference plane is not a plane of material symmetry and coexisting with a subsonic surface wave. The occurrence of a supersonic surface wave travelling in a direction e 1 with speed v s implies that there are two homogeneous plane waves, with slowness vectors s i and s r such that s i . e 1 = S r . e 1 = v -1 s , which comprise the incident and reflected waves in a case of simple reflection at the traction-free boundary. Supersonic surface waves may therefore be found by searching within a suitably defined space of simple reflection, R . This is the approach which has led to the new results mentioned above and the principal conclusions of part I are re-examined here from the same point of view. It is found that, whereas the secluded supersonic surface waves in transversely isotropic media correspond to isolated points on a curvilinear projection of R which does not intersect the curve representing subsonic surface waves, the symmetric surface waves studied in part I define a curve which may lie partly inside and partly outside a projection of R in the form of a region, the interior points representing supersonic and the exterior points subsonic surface waves. This discussion is preceded by a simplification of the existence-uniqueness theorem proved in part I and followed by a reconsideration of the possibility that an inhomogeneous plane elastic wave can qualify as a surface wave. Such one-component surface waves do exist, but a symmetric surface wave necessarily contains two inhomogeneous plane waves.

Sound reflection of acoustic porous metasurfaces under uniform mean flow

2021 ◽  
Vol 263 (4) ◽  
pp. 2601-2608
Author(s):  
Renhao Qu ◽  
Jingwen Guo ◽  
Yi Fang ◽  
Siyang Zhong
Keyword(s):  
Surface Wave ◽  
Critical Incident ◽  
Incident Angle ◽  
Low Frequency ◽  
Noise Attenuation ◽  
Mean Flow ◽  
Background Flow ◽  
Reflected Waves ◽  
Acoustic Performance ◽  
Sub Wavelength

Acoustic metasurfaces are artificial 2D structures with a sub-wavelength thickness that can realize some exotic properties such as non-trivial refraction, broadband and low frequency absorption. However, most relevant studies are still in a static medium, hindering their realistic applications in aviation, where background flow exists. To address it, the effects of mean flow on the acoustic performance of metasurfaces, which is designed based on the generalized Snell's law (GSL) to achieve anomalous reflections, are systemically studied. Firstly, an analytical model of GSL taking the effect of background uniform mean flow into account is built, in which the wavenumbers of both incident and reflected waves are corrected. Then, taking an acoustic porous metasurface for instance, the effectiveness of the derived model is validated by numerical simulations. Results reveal that the reflected waves are deflected in the presence of background flow. The critical incident angle, at which the incident sound wave is converted to surface wave, decreases with the increasing flow velocity. Since the converted surface wave can only propagate along the metasurface, there is little sound energy radiated into far field, which is benefit for the noise attenuation in the presence of flow.

Diffraction of a surface wave incident at an arbitrary angle on the edge of a plane

1966 ◽  
Vol 8 (1) ◽  
pp. 117-121
Author(s):  
M. S. Bobrovnikov ◽  
V. N. Ponomareva ◽  
V. G. Myshkin ◽  
R. P. Starovoitova
Keyword(s):  
Surface Wave ◽  
Wave Incident ◽  
Arbitrary Angle
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