Barker coded thermal wave detection and matched filtering for defects in CFRP/Al honeycomb structure

CFRP/Al honeycomb panel components have been used in harsh environment for a long time, which is easy to cause debonding and water accumulation and other defects related to operation safety. Taking CFRP/Al honeycomb composite plate with debonding and water accumulation defects as the test sample, the halogen lamp driven by Barker coded modulation pulse compression signal was used as the external excitation source, and the infrared thermal image sequence of the sample surface was collected by infrared camera. Three dimensional matched filter was designed and used to process the acquired image sequence. With 4 different quantization methods, 8 thermal wave response results of debonding and water accumulation defects were obtained, and these results were compared and analyzed from multiple aspects and the signal-to-noise ratio (SNR) was evaluated. The results show that Barker coded excitation has the advantages of simple modulation and easy implementation, and it can effectively suppress the background noise of infrared thermal image and improve the SNR by combining with three dimensional matched filter, and can effectively detect the internal debonding and water accumulation defects of composite materials under the condition of low-power thermal excitation.