ジュール熱による瞬時加熱温度場のサーモグラフィ計測に基づく非破壊欠陥計測

抄録

A new nondestructive inspection technique using infrared thermography was proposed, in which the thermal image of the surface temperature on a heated sample was used to identify flaws and defects. Joule effect heating by an electric current was employed to heat the sample instantaneously. Both numerical and experimental studies were conducted on the resolution and the availability in the detection of the through-thickness and surface cracks embedded in steel plates. The results showed that a singular concentration was observed at the crack tips in the surface temperature field in the transient stage of heat conduction, and the cracks were found to be sensitively detected from such a singular temperature field in the early transient stage. This technique was also applied to the inspection of the delamination defect in carbon-fiber reinforced plastics (CFRP), again using Joule effect heating. The subsurface defect was found to be identified from the localized low-temperature region appearing on the sample surface. It was found that the proposed technique is applicable to the damage inspection in CFRP as well as the flaw inspection in metallic materials.