Structural integrity assessment via coating tolerant thermography

This paper describes a new thermal method, coating tolerant forced diffusion thermography, specifically designed to inspect large steel bridge structures. Coating tolerant thermography separates the effects of structural defects and variations in emissivity. The technique is a derivative of force diffusion thermography which uses patterned radiation to force heat flow in-plane to specifically target cracks. This paper presents the fundamentals of coating tolerant forced diffusion thermography including the mathematical bases for the separation of thermal gradients and emissivity gradients. Also presented are case studies including the inspection of a bridge girder.

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