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Full-field localization of plate-thickness inhomogeneities through the local changes in the wavenumber of Lamb waves measured with pulsed TV holography

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Show simple item record Deán Ben, José Luis Trillo Yáñez, María Cristina Fernández Doval, Ángel Manuel Fernández Fernández, José Luis 2016-06-02T07:15:20Z 2016-06-02T07:15:20Z 2008-06-04
dc.description.abstract A new capability of TV holography, also known as electronic speckle pattern interferometry (ESPI), is presented for locating and imaging slightly thinned or thickened areas in metallic plates. It is based on the measurement of the wavenumber variation of narrowband Lamb waves as they propagate through these plate-thickness inhomogeneities. The relation between frequency and phase velocity of all Lamb modes depends on the elastic constants of the material the plate is made of (two parameters in isotropic materials) and on the plate thickness. Therefore, the associated dispersion curve of each mode present wavenumber changes that are sensitive to a thickness reduction. We have formerly developed a double-pulsed TV holography system which allows the full-field measurement of the instantaneous out-of-plane displacement field induced by surface acoustic waves and, by further processing, to calculate maps of the acoustic amplitude and phase. A method based on further analysis of the acoustic complex-displacement map is therefore proposed to locate and characterize such smooth thickness reductions. In particular, we calculate a map of the local wavenumber of the acoustic wave as the modulus of the two-dimensional gradient of the mechanical phase. Hence, as the variations in the wavenumber correspond to variations in the plate thickness, the local thickness reductions and increments can be detected in this map. Within the resolution limits imposed by the wavelength of the Lamb wave, this method allows also to contour the shape of the inhomogeneities. The technique is demonstrated herein by imaging a X-shaped recess machined on an aluminium plate. spa
dc.description.sponsorship Ministerio de Educación y Ciencia y Comisión Europea (FEDER) | Ref. DPI2005-09203-C03-01 spa
dc.description.sponsorship Dirección Xeral de Investigación, Desenvolvemento e Innovación, Xunta de Galicia | Ref. PGIDIT06PXIC303193PN spa
dc.description.sponsorship Universidad de Vigo | Ref. I608122F64102 spa
dc.language.iso eng spa
dc.title Full-field localization of plate-thickness inhomogeneities through the local changes in the wavenumber of Lamb waves measured with pulsed TV holography spa
dc.type conferenceObject spa
dc.rights.accessRights openAccess spa
dc.identifier.doi 10.1117/12.802983
dc.identifier.editor spa
dc.publisher.departamento Física aplicada spa
dc.conferenceObject.type Comunicación extensa internacional spa
dc.identifier.conferenceObject Eighth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, Ancona, Italia, 17-20 junio 2008 spa
dc.identifier.conference spa
dc.publisher.grupoinvestigacion Grupo de Metroloxía Óptica spa
dc.subject.unesco 3311.11 Instrumentos Opticos spa
dc.subject.unesco 2209.07 Holografía spa
dc.subject.unesco 2201.09 Ultrasonidos spa 2016-05-31T21:41:10Z

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