NDE of multilayered system using laser-ultrasonic SAW

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Proceedings titleProceedings of the World Conference on Ultrasonics
ConferenceWorld Congress on Ultrasonics, September 7-10 2003, Paris France
Pages14351438; # of pages: 4
AbstractLaser-ultrasound spectroscopy, a non-contact ultrasonic technique was used to characterize a zinc coating on a steel substrate. This characterization is based on fitting the measured velocity dispersion of surface acoustic waves (SAW) to the dispersion calculated using the conjugates gradients algorithm (C.G). A short laser pulse was used to generate a wideband pulse of ultrasound and a laser interferometer was used for its detection. From a large number of echoes we identified the one corresponding to the SAW. Furthermore other useful informations were obtained from these data like attenuation and surface skimming longitudinal wave velocity. Measurements of the velocity dispersion of the Rayleigh wave were achieved up to 50 MHz. The evaluation of layer's parameters performed for similar cases, on a pseudo-experimental model, were obtained with accuracy better than 1% for (h,μ) and about 4% to 6% for λ. To account for the diffusion of iron in zinc, we modelled the system by three media: 2 layers of zinc on a steel substrate. The thicknesses and densities of the 2 layers are estimated from the percentage of iron in mass, and then the Lamé coefficients of the three media are evaluated by resolution of the inverse problem. The Rayleigh velocity dispersion curve resulting from these values presents a good agreement with the measured one.
Publication date
AffiliationNRC Industrial Materials Institute; National Research Council Canada
Peer reviewedYes
NPARC number21273112
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Record identifier0c5ee54e-493a-4b7a-ae14-9165cb40ff3b
Record created2014-12-15
Record modified2016-05-09
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