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Advances in Air-Coupled Lamb Wave Scanning
Symposium on the Application of Geophysics to Engineering and Environmental Problems, 2007Impact-echo is an effective method for the nondestructive evaluation of in-situ concrete members and has progressively developed over the past 20 years. This study outlines recent advances in the adoption of microphone-based signal acquisition in order to perform rapid non-contact impact echo scanning, in the context of the recently proposed Lamb wave ...
Alex Gibson +2 more
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Air-coupled ultrasound inspection of various materials
Ultrasonics, 2002Conventional ultrasound inspection, a standard non-destructive testing method, uses a coupling medium (e.g. water) because of impedance mismatch. This liquid contact is a drawback because it prevents inspection of many materials. There is a need, then, for air-coupled ultrasound testing, which is now feasible because of low impedance focused narrow ...
R, Stoessel +3 more
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Air-coupled laser vibrometry: analysis and applications
Applied Optics, 2008Acousto-optic interaction between a narrow laser beam and acoustic waves in air is analyzed theoretically. The photoelastic relation in air is used to derive the phase modulation of laser light in air-coupled reflection vibrometry induced by angular spatial spectral components comprising the acoustic beam.
Igor, Solodov +2 more
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Air-coupled ultrasonic evaluation of food materials
Ultrasonics, 2007This research was performed with the aim of detecting foreign bodies and additives within food products, and to measure selected acoustic properties, without contact to the sample. This would allow use in manufacturing plants on production lines, where contacting the product for ultrasonic inspection would not be feasible.
P, Pallav, D A, Hutchins, T H, Gan
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The use of air-coupled ultrasound to test paper
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 2001Capacitance transducers containing a thin polymer membrane have been used to transmit ultrasonic signals with frequencies in excess of 1 MHz through various paper products such as paper and cardboard. At normal incidence, a resonance was visible in thicker samples, the frequency of which could be correlated to parameters such as the thickness of the ...
C S, McIntyre +3 more
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Calibration of Air-Coupled Ultrasonic Transducers
2021 IEEE International Ultrasonics Symposium (IUS), 2021Air-coupled ultrasonic transducers working at frequencies over 100 kHz have been widely used in the past for NDT applications and are a very attractive alternative when test specimens cannot enter in contact with water. In these cases, and in order to determine transducer performance it is sufficient to measure transducer two-way insertion loss and ...
Julio Quirce +2 more
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Multimode Air-Coupled Excitation of Micromechanical Structures
IEEE Transactions on Instrumentation and Measurement, 2008The development of an acoustic measurement system for multimode air-coupled excitation and detection of micrometer-scale cantilever structures, which are, for example, used in micro-electromechanical systems (MEMSs), is detailed and reported for the first time.
Cetin Cetinkaya +3 more
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Air-coupled ultrasonic testing of diffusion bonds
Ultrasonics, 2002The diffusion bond between two steel plates can be ultrasonically evaluated, at normal incidence in an immersion experiment, by analyzing the frequency dependence of the echo reflected from the imperfect bond. The interfacial stiffness, derived from the echo amplitude, correlates well with the bond-strength.
Filip, Windels, O, Leroy
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Air-coupled piezoelectric detection of laser-generated ultrasound
IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, 1993A pulsed laser has been used to generate ultrasonic transients in samples of metal and fiber-reinforced polymer composite material. These have been detected using an air-coupled piezoelectric transducer. It is demonstrated that such a transduction system can be used for longitudinal waves in bulk material, Rayleigh waves at solid surfaces and Lamb ...
Hutchins, D.A. +3 more
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The Journal of the Acoustical Society of America, 1979
A method and apparatus for improved detection of reflected seismic energy through detection of air pressure variations in air above an air/earth surface interface. One form of apparatus suitable for detection in air of seismic energy waves emanating from beneath the earth surface consists of supporting a collecting reflecting member over a designated ...
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A method and apparatus for improved detection of reflected seismic energy through detection of air pressure variations in air above an air/earth surface interface. One form of apparatus suitable for detection in air of seismic energy waves emanating from beneath the earth surface consists of supporting a collecting reflecting member over a designated ...
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