Cristin-resultat-ID: 1478378
Sist endret: 23. november 2017 13:11
NVI-rapporteringsår: 2017
Resultat
Vitenskapelig artikkel
2017

Beam diffraction effects in the backward wave regions of viscoelastic leaky Lamb modes for plate transmission at normal incidence

Bidragsytere:
  • Magne Aanes
  • Kjetil Daae Lohne
  • Per Lunde og
  • Magne Vestrheim

Tidsskrift

IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
ISSN 0885-3010
e-ISSN 1525-8955
NVI-nivå 1

Om resultatet

Vitenskapelig artikkel
Publiseringsår: 2017
Publisert online: 2017
Trykket: 2017
Volum: 64
Hefte: 10
Sider: 1558 - 1572

Importkilder

Scopus-ID: 2-s2.0-85023780115

Beskrivelse Beskrivelse

Tittel

Beam diffraction effects in the backward wave regions of viscoelastic leaky Lamb modes for plate transmission at normal incidence

Sammendrag

Plane-wave theory for fluid-embedded isotropic plates is often used in ultrasonic guided-wave applications, and to estimate wall thickness, corrosion, or sound velocities in plates and pipes. In such structures, measured ultrasonic transmission through the solid material is affected by acoustic beam diffraction effects, and the results may deviate from plane-wave descriptions, which are insufficient to describe the complex effects that occur. When exciting a fluid-embedded steel plate with a pulsed ultrasonic beam at normal incidence, resonance frequency downshift, axial sound pressure level (SPL) increase, and beam narrowing have been observed, for measured resonance peaks in the frequency regions of certain leaky Lamb mode branches of the plate. In the ranges of other leaky Lamb mode branches, the effects observed are different. Measurements, finite element and angular spectrum modeling are used to indicate a close connection between these beam diffraction phenomena and the backward wave characteristics of certain leaky Lamb mode pairs, in the frequency and Poisson’s ratio regions around coincidence of two Lamb mode cutoff frequencies of similar symmetry. In particular, such observations made for the steel plate’s fundamental thickness-extensional (TE) mode appear to be caused by acoustic beam excitation of the backward wave regions of the 𝑺−𝟐𝒗𝒍 and 𝑺𝟐𝒗𝒍 leaky Lamb modes.

Bidragsytere

Magne Aanes

  • Tilknyttet:
    Forfatter
    ved Institutt for fysikk og teknologi ved Universitetet i Bergen

Kjetil Daae Lohne

  • Tilknyttet:
    Forfatter
    ved Christian Michelsen Research ved NORCE Norwegian Research Centre AS

Per Lunde

  • Tilknyttet:
    Forfatter
    ved Institutt for fysikk og teknologi ved Universitetet i Bergen

Magne Vestrheim

  • Tilknyttet:
    Forfatter
    ved Institutt for fysikk og teknologi ved Universitetet i Bergen
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