Journal ArticleDOI
Practical considerations for the rapid inspection of composite materials using laser-based ultrasound
TLDR
In this paper, an automated laser-based ultrasound system is described that has sufficient sensitivity to detect typical flaws of interest in composite materials without causing surface damage to the part under test.About:
This article is published in Ultrasonics.The article was published on 1994-09-01. It has received 45 citations till now. The article focuses on the topics: Laser ultrasonics & Ultrasonic sensor.read more
Citations
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Journal ArticleDOI
Optical remote measurement of ultrasound
Richard Dewhurst,Q Shan +1 more
TL;DR: In this paper, a range of optical techniques are presented, including optical self-mixing, phase modulators and photorefraction-based interferometers for remote detection of ultrasound.
Journal ArticleDOI
Non-destructive evaluation of composite materials using a capacitive imaging technique
Xiaokang Yin,David A. Hutchins +1 more
TL;DR: In this paper, the application of the capacitive imaging technique to the inspection of composite materials was described, and the fundamental theory of the imaging technique was briefly described, as well as the experimental results indicated that it could be used to detect cracks and delaminations in the glass fiber composite, defects in the aluminium core through the glass fibre face, and surface features on the carbon fibre specimens.
Journal ArticleDOI
Air-coupled ultrasonic estimation of viscoelastic stiffnesses in plates
Abstract: Materials characterization by means of megahertz air-coupled ultrasound is reported in this paper. In plates of composite laminates the reconstruction of a function closely related to the transmission coefficient has been accomplished using leaky guided waves. The spatial and frequency dependence of the transmitted leaky waves have been measured for a variety of plates, including aluminum-aramid and graphite-epoxy. These results are based on a general method, developed in this paper, to reconstruct a transmission function experimentally from scans both of receiver position and incident angle. A synthetic aperture technique is utilized to reduce the measurements by forming an effective wide-angle focused aperture. This synthetic focused aperture is obtained experimentally by summing measured signals coherently for many transmitter-receiver separations and summing incoherently for many transducer angles with respect to the plate normal. These results have been employed to deduce, with high precision, a function related to the plane-wave transmission coefficient of the plate over the frequency and angular bandwidths covered by the measurements. Calculation of this function is demonstrated, and the source of its deviation from the plane-wave transmission coefficient is explained. The experimental results show good agreement when compared to three-dimensional theoretical beam calculations. The high degree of accuracy in the measured transmission function has been exploited to construct an efficient inversion algorithm to estimate the viscoelastic material properties and/or sample thickness.
Journal ArticleDOI
Industrially viable non-contact ultrasound
Stuart B. Palmer,Steve Dixon +1 more
TL;DR: In this paper, the Warwick Laser Ultrasound Group have described some of the research and development of non-contact ultrasonic transducers and techniques that the Warwick laser ultrasound group have made over a number of years.
Journal ArticleDOI
A conjugate optical confocal Fabry-Perot interferometer for enhanced ultrasound detection
Q Shan,Cm Chen,Richard Dewhurst +2 more
TL;DR: In this paper, an optical detection scheme using a confocal Fabry-Perot interferometer and conjugate detection is described, where the conjugates are derived from optical back reflection and optical transmission through the interferometers.
References
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Journal ArticleDOI
Point‐source representation for laser‐generated ultrasound
TL;DR: In this paper, a formal solution for the double (Hankel-Laplace) transform of the displacement potentials is obtained for axially symmetric configurations, with the point source lying within or on the surface of a half-space or a plate.
MonographDOI
The Fabry-Perot Interferometer : History, Theory, Practice and Applications
TL;DR: In this article, the authors present an overview of the basic elements of optical spectroscopy, including the Plane Fabry-Perot Interferometer (PFI), the Spherical FFI (SFI), and the FFI-MIMO (FIFO) interferometer.
Journal ArticleDOI
Mechanisms of pulsed photoacoustic generation
TL;DR: In this article, the mechanisms by which ultrasonic transients may be generated by pulsed laser irradiation are reviewed, with particular reference to the wave forms resulting in both fluid and solid media.
Journal ArticleDOI
Directivity patterns of laser‐generated ultrasound in aluminum
TL;DR: Directivity patterns of laser generated longitudinal and shear waves in aluminum have been determined experimentally, for laser power densities both above and below the threshold for plasma formation on the target's surface as mentioned in this paper.