Rapid inspection of composites using laser-based ultrasound

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1993
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McKie, Andrew
Addison, Robert
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Review of Progress in Quantitative Nondestructive Evaluation
Center for Nondestructive Evaluation

Begun in 1973, the Review of Progress in Quantitative Nondestructive Evaluation (QNDE) is the premier international NDE meeting designed to provide an interface between research and early engineering through the presentation of current ideas and results focused on facilitating a rapid transfer to engineering development.

This site provides free, public access to papers presented at the annual QNDE conference between 1983 and 1999, and abstracts for papers presented at the conference since 2001.

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Abstract

Current techniques for automated ultrasonic inspection of airframe structures can only be used to examine limited areas which have large radii of curvature. Manual inspection techniques are required in areas having small radii. Laser-based ultrasound (LBU) offers the potential to rapidly inspect large-area composite structures having contoured geometries, without restriction to large radii of curvature [1–4]. The key components that comprise an LBU rapid inspection system are the generation and detection lasers, a 2D scanner and a suitably fast data acquisition system. These must be integrated to provide an areal scan rate of at least 100 ft2/hr based on a 0.5″ × 0.5″ pixel size. In this paper results are presented of an investigation of the relative merits of using a CO2 laser versus a Nd:YAG laser for thermo-elastic ultrasonic generation in composite materials. In our previous studies, ultrasonic C-scan images of components were acquired with the LBU system by mechanically translating the test specimen in front of the stationary generation and detection laser beams [2–4]. If the scan is to be done rapidly, this technique becomes increasingly difficult and more expensive as the mass of the part increases. To fully realize the high speed scanning potential of a same side laser-in/laser-out inspection system, it is necessary to deflect the laser beams across the part surface. An implementation of angular scanning of the generation and probe laser beams across the part surface is described. A data acquisition scheme that has been used to demonstrate data acquisition rates of 33 waveforms/sec (for 200 point waveforms) is also described.

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Fri Jan 01 00:00:00 UTC 1993