Cooling down thermography: principle and results for NDE

ABSTRACTCooling Down Thermography (CDT) represents a novel approach to thermal nondestructive testing: the sample is previously heated in an oven in order to obtain a uniform temperature, then it is exposed to a lower ambient temperature.An infrared camera monitors the surface temperature decay in order to reveal internal defects.While this approach presents clear disadvantages in terms of versatility, it allows for a faster and deeper penetration in thesample, and it has therefore mainly been used in order to reveal deep defects in insulating materials.Keywords: thermography, nondestructive evaluation, infrared. 1. INTRODUCTION Quality assurance is assuming a growing importance in the industrial production both for economic and safety reasons.While destructive testing methods need to destroy some samples of the production in order to statistically assure quality,nondestructive evaluation techniques allow for a quality test on every single specimen leaving the production ime. This isimportant in cases where statistical methods can not be easily applied or where the cost of the specimen is too high fordestructive testing.