Debonding defects detection of FMLs based on long pulsed infrared thermography technique

Abstract

Fiber metal laminates (FMLs) are the popular materials in the fields of aerospace, automobile and rail transportation. In the process of preparation and service, the defects of matrix, fiber fracture and fiber matrix debonding are easily produced, which poses a threat to the safety of FMLs’ quality, performance and the operational safety of the aircraft and other equipment using the material. Aiming at developing a method for defects detection in FMLs by long pulsed infrared thermography, test was applied to FMLs with debonding defects. Halogen lamps were used as active heat source into the sample, and the infrared image sequence was collected with an infrared camera A325sc. Thermal wave signal reconstruction, pulsed phase thermography and principal component analysis methods were used to process the original image sequences. Experimental results show that the signal-to-noise of processed images by these three methods are all increased, while that of principal component analysis method increases significantly under the same given test parameters, and it can be used to detect the defects in FMLs.