サーモグラフィックNDTによる複合材料の欠陥・損傷計測

概要

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Thermographic NDT is developed for the inspection of the delaminated defects embedded in fiber reinforced plastic samples. The location and shape of the defects are identified from the surface temperature distribution appear on the sample by the heat insulation effect of the defects, when the sample is under heating and/or cooling. The resolution is examined for the artificial delaminated defects both in CFRP and GFRP samples, when the conventional infrared radiation heating is adopted. Experimental results show that the radiation heating is not effective for the accurate defect inspection of the CFRP sample due to its high thermal conductivity. The Joule effect heating, on the other hand, is found to be effective for the similar sample. Two methods of the Joule effect heating, a direct current application and an induction heating, are investigated. The induction heating thermographic NDT is degraded in the resolution of the defects, compared with the direct current thermographic NDT, because of the inhomogeneity in the induced current field. This can be improved by the use of an image processing technique in the analysis of the thermal images. Further the present thermographic NDT technique is applied for the inspection of the GFRP sample with the actual delaminated damage under cyclic straining. The possible detection of the subsurface damage is discussed.
一般社団法人日本機械学会の論文
1993-09-25