Air-coupled acoustic imaging with zero-group-velocity Lamb modes
نویسندگان
چکیده
منابع مشابه
High contrast air-coupled acoustic imaging with zero group velocity lamb modes.
The well known zero in the group velocity of the first-order symmetric (S1) plate wave mode has been exploited in air-coupled ultrasonic imaging to obtain significantly higher sensitivity than can be achieved in conventional air-coupled scanning. At the zero group velocity point at the frequency minimum of the S1 mode, a broad range of wavenumbers couple into the first-order symmetric mode at n...
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Guided waves in a free isotropic plate (symmetric S(n) and antisymmetric A(n) Lamb modes) exhibit a resonant behavior at frequencies where their group velocity vanishes while their phase velocity remains finite. Previous studies of this phenomenon were limited to isotropic materials. In this paper, the optical generation and detection of these zero-group velocity (ZGV) Lamb modes in an anisotro...
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Hollow cylinders used in the industry must be regularly inspected. Elastic guided waves, similar to Lamb modes in a plate, can propagate in the axial direction or around the circumference. They are sensitive to geometrical and mechanical parameters of the cylindrical shell. The objective of this paper is to show that zero group velocity (ZGV) Lamb modes can be used to bring out anisotropy and t...
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The local resonances of a free isotropic elastic plate are investigated using laser ultrasonic techniques. Experimental results are interpreted in terms of zero group velocity Lamb modes and edge mode. At a distance from the edge larger than the plate thickness a sharp resonance is observed at the frequency where the group velocity of the first symmetrical Lamb mode vanishes. Close to the edge ...
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A non-contact laser based ultrasonic technique is proposed for detecting plate thickness variations due to corrosion and adhesive disbonds between two plates. The method exploited the resonance at the minimum frequency of the S1 Lamb mode dispersion curve. At this minimum frequency the group velocity vanishes, whereas the phase velocity remains finite. The energy deposited by the laser pulse, g...
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ژورنال
عنوان ژورنال: Applied Physics Letters
سال: 2003
ISSN: 0003-6951,1077-3118
DOI: 10.1063/1.1613046