Detection of Superficial Defects in the Insulation Layers of Aviation Cables by Infrared Thermographic Technique

Superficial defects in the insulation layers of aviation cables can cause serious failures of and disasters for aircraft. Considering the critical importance of safety for aircraft, there is a need to develop a nondestructive technique to detect these kinds of defects in aviation cables. The objective of this paper is to investigate defect detection in aviation cable insulation by an infrared technique. The temperature distribution in the tested cable insulation surface under different thermal excitations and its time variation law are firstly analyzed by numerical simulation. Experimental testing is simultaneously conducted to study the influence of insulation wear defects on the temperature distribution of the cable surface. Complex background temperature distributions are eliminated in infrared images to improve the recognition of defects and extract the difference of the cable surface to draw a curve. The obtained results clearly indicate that the temperature variation interval in the curve can successfully reflect the sizes and locations of insulation defects.