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Proceedings Paper

Comparison of lock-in and pulse-phase thermography for defect characterization in FRP composites applied to concrete
Author(s): Jeff Brown; Sai Harsha Chittineni
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Paper Abstract

Thermal imaging is a well-established technique for the non-destructive evaluation of FRP composites applied to reinforced concrete. Defect characterization using IR thermography, however, remains a topic of on-going research, and there are currently no universally accepted standards for data collection or interpretation. This research involved large scale thermography inspection of two FRP strengthened bridge girders that were removed from service after approximately 10 years of service in a potentially corrosive marine environment. Trial inspections were performed on test areas where defects could be identified using sounding methods. Two procedures showed the most promise for identifying and characterizing defects: sinusoidal (lock-in style) heating with periods ranging from 5 s to 40 s and constant step heating for 30 s followed by 60 s of cooling. Both methods resulted in a series of phase images that provided insight into the depth and general nature of detected defects. This paper presents the findings of a comparison study between these two thermal imaging techniques.

Paper Details

Date Published: 12 May 2015
PDF: 8 pages
Proc. SPIE 9485, Thermosense: Thermal Infrared Applications XXXVII, 94850B (12 May 2015); doi: 10.1117/12.2177260
Show Author Affiliations
Jeff Brown, Embry-Riddle Aeronautical Univ. (United States)
Sai Harsha Chittineni, Embry-Riddle Aeronautical Univ. (United States)

Published in SPIE Proceedings Vol. 9485:
Thermosense: Thermal Infrared Applications XXXVII
Sheng-Jen (Tony) Hsieh; Joseph N. Zalameda, Editor(s)

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