Relationship between Inspection Time and Frequency Components of Input and Reflected Thermal Waves in Active Thermographic Non-Destructive Inspection

Abstract

Experiments and numerical simulations for a carbon fiber reinforced plastic specimen were performed to investigate the relationship between the time required for detecting subsurface defects and the frequency components of the thermal waves propagating within the specimen. Experimental results showed that the required inspection time was shortened by increasing the frequency of the input thermal wave. However, if the attenuation during thermal wave propagation is large enough to render the detection of the thermal wave reflected at the subsurface defect impossible, the inspection time exceeds the time estimated by theoretical calculation.