DocumentCode :
1033849
Title :
Electrical approach to defect depth estimation by stepped infrared thermography
Author :
Gupta, R. ; Tuli, S.
Author_Institution :
Centre for Appl. Res. in Electron., Indian Inst. of Technol. Delhi, New Delhi, India
Volume :
151
Issue :
4
fYear :
2004
fDate :
7/2/2004 12:00:00 AM
Firstpage :
298
Lastpage :
304
Abstract :
An electrical modelling and analysis is presented for thermal nondestructive evaluation of materials by stepped infrared (IR) thermography. A one-dimensional (1D) electrical analysis based on the Laplace transform technique of network-analysis and time delay in an RC ladder network is given for defect depth estimation. Defect depth is evaluated based on the time instants at which surface temperature evolution over the defect and nondefect regions of the material deviates from its constant initial slope, corresponding to the response of a semi-infinite material under similar conditions of step heating. The method is applicable even for three-dimensional geometries of materials having unknown thermal properties and variable surface emissivity. Experimental and simulated results validate the proposed method and give good estimation of defect depth, even under noisy conditions for a thermally anisotropic material and a nonflat bottom type of defect.
Keywords :
Laplace transforms; carbon fibre reinforced plastics; carbon fibres; carbon steel; delay circuits; infrared imaging; ladder networks; nondestructive testing; C; Laplace transform technique; RC ladder network; defect depth estimation; electrical model; infrared thermography; network-analysis; noisy conditions; nondefect regions; one-dimensional electrical analysis; semiinfinite material; surface emissivity; surface temperature evolution; thermal nondestructive evaluation; thermal properties; thermally anisotropic material; three-dimensional geometry; time delay;
fLanguage :
English
Journal_Title :
Science, Measurement and Technology, IEE Proceedings -
Publisher :
iet
ISSN :
1350-2344
Type :
jour
DOI :
10.1049/ip-smt:20040564
Filename :
1315473
Link To Document :
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