Scanning laser source and scanning laser detection techniques for different surface crack geometries
Edwards, R. S. (Rachel S.), Dutton, B. (Ben), Clough, A. R. and Rosli, M. H. (2012) Scanning laser source and scanning laser detection techniques for different surface crack geometries. In: Review of Progress in Quantitative Nondestructive Evaluation, Burlington, VT, 17th-22nd July 2011. Published in: AIP Conference Proceedings, Volume 1430 (Number 31). pp. 251-258.
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Official URL: http://dx.doi.org/10.1063/1.4716237
Standard test samples typically contain simulated defects such as slots machined normal to the surface. However, real defects will not always propagate in this manner; for example, rolling contact fatigue on rails propagates at around 25º to the surface, and corrosion cracking can grow in a branched manner. Therefore, there is a need to understand how ultrasonic surface waves interact with different crack geometries. We present measurements of machined slots inclined at an angle to the surface normal, or with simple branched geometries, using laser ultrasound. Recently, Rayleigh wave enhancements observed when using the scanning laser source technique, where a generation laser is scanned along a sample, have been highlighted for their potential in detecting surface cracks. We show that the enhancement measured with laser detector scanning can give a more significant enhancement when different crack geometries are considered. We discuss the behaviour of an incident Rayleigh wave in the region of an angled defect, and consider mode-conversions which lead to a very large enhancement when the detector is close to the opening of a shallow defect. This process could be used in characterising defects, as well as being an excellent fingerprint of their presence.
|Item Type:||Conference Item (Paper)|
|Subjects:||Q Science > QC Physics|
|Divisions:||Faculty of Science > Physics|
|Library of Congress Subject Headings (LCSH):||Rayleigh waves, Surfaces (Technology) -- Defects, Nondestructive testing|
|Journal or Publication Title:||AIP Conference Proceedings|
|Publisher:||American Institute of Physics|
|Page Range:||pp. 251-258|
|Access rights to Published version:||Restricted or Subscription Access|
|Funder:||European Research Council (ERC)|
|Grant number:||202735 (ERC)|
|Conference Paper Type:||Paper|
|Title of Event:||Review of Progress in Quantitative Nondestructive Evaluation|
|Type of Event:||Conference|
|Location of Event:||Burlington, VT|
|Date(s) of Event:||17th-22nd July 2011|
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