28 March 1995 Crawling spot thermal nondestructive testing (NDT) for plaster inspection and comparison with dynamic thermography with extended heating
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Abstract
Defects in building materials located parallel to the front surface, like plaster detachment, or perpendicularly, such as cracks, are detected creating a space-varying heat flux. A variant of the `flying spot' technique called `crawling spot' was developed in order to fit requirements of these materials. This nondestructive method is performed with a localized radiant heating of the surface and synchronized local temperature measurement in the IR band. The identification of delaminations and cracks was theoretically and experimentally studied using two different procedures. Results obtained for plaster detachments were compared with dynamic thermography, applied with an extended excitation of the surface and analysis of the normalized thermal contrast both in amplitude and time. Another technique requires a continuously moving spot to heat the surface while a sequence of thermograms is recorded. The temperature profile of each pixel has to be reconstructed according to the spot speed and trajectory. This procedure was applied to stone crack detection. The experimental apparatus is thoroughly described.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Paolo Giulio Bison, Paolo Giulio Bison, Alberto Braggiotti, Alberto Braggiotti, Chiara Bressan, Chiara Bressan, Ermanno G. Grinzato, Ermanno G. Grinzato, Sergio Marinetti, Sergio Marinetti, Andrea Mazzoldi, Andrea Mazzoldi, Vladimir P. Vavilov, Vladimir P. Vavilov, } "Crawling spot thermal nondestructive testing (NDT) for plaster inspection and comparison with dynamic thermography with extended heating", Proc. SPIE 2473, Thermosense XVII: An International Conference on Thermal Sensing and Imaging Diagnostic Applications, (28 March 1995); doi: 10.1117/12.204880; https://doi.org/10.1117/12.204880
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