<title>Dual-band infrared imaging to detect corrosion damage within airframes and concrete structures</title>

Abstract

We are developing dual-band infrired (DBIR) imaging and detection techniques to inspect airframes and concrete bridge decks for hidden corrosion damage. Using selective DBIR image ratios, we enhanced surface temperature contrast and removed surface emissivity noise associated with clutter. Our surface temperature maps depicted defect sites, which heat and cool at different rates than their surroundings. Our emissivity-ratio maps tagged and removed the masking effects of surface clutter. For airframe inspections, we used time-resolved DBIR temperature, emissivity-ratio and composite thermal inertia maps to locate corrosion-thinning effects within a flash-heated Boeing 737 airframe. Emissivity-ratio maps tagged and removed clutter sites from uneven paint, dirt and surface markers. Temperature and thermal inertia maps characterized defect sites, types, sizes, thicknesses, thermal properties and material-loss effects from airframe corrosion. For concrete inspections, we mapped DBIR temperature and emissivity-ratio patterns to better interpret surrogate delamination sites within naturallyheated, concrete slabs and removed the clutter mask from sand pile-up, grease stains, rocks and other surface objects. SPIE Vol. 2245 Thermosense XVI (1994)! 203 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/21/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx of objects on the concrete block, see Figure 6, were both warmer than the rocks and had higher emissivity-ratio values which contrasted more with the concrete than the rocks. Also, we note that clutter sites from surface objects on the concrete block had sharp edges, whereas surface temperature pauerns of defect sites from surrogate delaminations within concrete slabs had edges which were less well defined. We expect these features to help distinguish corrosion-related delamination sites from surface clutter sites to clarify interpretation of concrete bridge deck inspections. 7.0 ACKNOWLEDGMENTS at the FAA Technical Center for their helpful suggestions. We are grateful for the support efforts of Gary Phipps, Craig Jones, Don Harmon and Pat Walter at Sandia National Laboratory, Albuquerque, NM where we inspected the Boeing 737 aircraft owned by the FAA/AANC (Aging Aircraft Nondestructive Inspection Center). We thank M. Lawrence and N. Nguyen for calibrated thermistor measurements, M. Gorvad for image processing, L. Hrubisch for the Aerogel samples, M. Finger, David Fields and Michael Carter for use of the Agema DBIR system, Ken Dolan, FAA Project Leader, for helpful suggestions and Sàtish Kulkarni, NDE Section Leader, for his support.

Infrared thermographic detector of hidden corrosion

“…In the two past decades, IR thermography has appeared as a well-established express NDT technique, also called thermal NDT (TNDT), which can be used for the detection of hidden corrosion (Vavilov et al, 1996;Marinetti et al, 2002;Marinetti and Vavilov, 2010;Cramer and Winfree, 1998;Prabhu and Winfree, 1993;Cadelano et al, 2016;API 571, 2004;Doshvarpassand, et al, 2019;Syed et al, 1993;Alcott, 1994;DelGrande and Durbin, 1994;Prati, 2000;Chulkov et al, 2016;Vavilov and Chulkov, 2012). The classical TNDT procedure (Figure 1) involves thermal stimulation of a test object by means of an optical heat source (convective and inductive heat sources are also used) and the monitoring of object surface with an IR imager.…”

“…The testing of rear surface corrosion in high-conductive materials, such as aluminum, requires using flash powerful heating and should be applied on painted surface to avoid spurious reflections. However, IR thermographic NDT has been successfully used in the inspection of corrosion in aluminum airframes (Syed et al, 1993;Alcott, 1994;DelGrande and Durbin, 1994;Prati, 2000;Chulkov et al, 2016;Vavilov and Chulkov, 2012). In this case, material loss from 25 to 30 per cent in areas of about 20 mm (aluminum panels of thickness 1-2 mm) can be detected.…”

Interfacial damage identification of steel and concrete composite beams based on piezoceramic wave method

“…The infrared thermal imaging method is one kind of nondestructive flaw detection technology: once the target being measured has a relative change in thermodynamic characteristics in the surrounding environment, infrared thermal imaging technology can be used to detect the change. [3, 4] However, due to a very fast infrared attenuation in the concrete, there are limitations for its application in the detection range. For a complex interface, the result of infrared detection technology is often inaccurate.…”

<title>Stimulated dual-band infrared computed tomography: a tool to inspect the aging infrastructure</title>

“…We use DBIR image ratios, from DBIR cameras which scan targets at infrared wavelengths of 3-5 pm and [8][9][10][11][12] pm. L o enhance surface temperature contrast and remove the mask of surface emissivity noise.…”