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Detection of cracks in metal sheets using pulsed laser generated ultrasound and EMAT detection

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Dixon, S., Burrows, S. E. (Susan E.), Dutton, B. (Ben) and Fan, Y.. (2011) Detection of cracks in metal sheets using pulsed laser generated ultrasound and EMAT detection. Ultrasonics, Vol.51 (No.1). pp. 7-16. ISSN 0041-624X

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Official URL: http://dx.doi.org/10.1016/j.ultras.2010.05.002

Abstract

A pulsed Nd: YAG laser with an approximately Gaussian beam shape is directed onto the surface of an aluminium sheet at an energy density below which damage by laser ablation occurs, generating Lamb waves in the sheet. The laser beam is raster scanned across the surface of the sample. The Lamb waves travel radially outwards from the generation point and are detected some distance away by an electromagnetic acoustic transducer with sensitivity to in-plane displacements of the sheet. A number of static EMATs are located around the edges of the sheet, some distance from the generation point. The presence of a crack-like defect on the sheet can be detected by either a sudden change in the ultrasonic waveform or by an enhancement in the frequency content of the waveform when the laser beam illuminates directly onto the crack.

Item Type:	Journal Article
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Divisions:	Faculty of Science > Engineering Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Nd-YAG lasers, Sheet-metal -- Analysis, Lamb waves
Journal or Publication Title:	Ultrasonics
Publisher:	Elsevier Science BV
ISSN:	0041-624X
Date:	January 2011
Volume:	Vol.51
Number:	No.1
Number of Pages:	10
Page Range:	pp. 7-16
Identification Number:	10.1016/j.ultras.2010.05.002
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Engineering and Physical Sciences Research Council (EPSRC), UK Research Centre in Nondestructive Evaluation (RCNDE), Rolls-Royce Group plc, RWE npower plc, National Nuclear Laboratory (Great Britain)
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URI:	http://wrap.warwick.ac.uk/id/eprint/5005