Proceedings Article | 7 July 1995
KEYWORDS: Corrosion, Thermography, Composites, Infrared radiation, Inspection, Metals, Infrared imaging, Computed tomography, Nondestructive evaluation, Line scan image sensors
Infrared computed tomography (IRCT) is a promising, non-contact, nondestructive evaluation tool used to inspect the mechanical integrity of large structures. We describe on-site, proof-of- principle demonstrations of IRCT to inspect defective metallic and composite structures. The IRCT system captures time sequences of heat-stimulated, dual-band infrared (DBIR) thermal maps for flash-heated and naturally heated targets. Our VIEW algorithms produce co- registered thermal, thermal inertia, and thermal-timegram maps from which we quantify the percent metal-loss corrosion damage for airframes and the defect sites, depths, and host- material physical properties for composite structures. The IRCT method clarifies the type of defect, e.g., corrosion, fabrication, foreign-material insert, delamination, unbond, void, and quantifies the amount of damage from the defect, e.g., the percent metal-loss from corrosion in metal structures, the depth, thickness, and areal extent of heat damage in multi-layered composite materials. Potential long-term benefits of IRCT technology are in-service monitoring of incipient corrosion damage, to avoid catastrophic failure, and production- monitoring of cure states for composite materials.
