Defect detection of GFRP laminates by barker code modulation excitation infrared thermal imaging

Abstract

During the preparation and service of GFRP laminates, due to the influence of manufacturing process, it is easy to produce debonding defect. This paper expounds the basic principle and test process of infrared nondestructive testing, which using the barker code modulation of the thermal wave to identify the GFRP laminate debonding defect. Through the establishment of infrared thermal imaging testing system, this paper studies its detection effect on defects with different diameter, depth and diameter-to-depth ratio, processes the image sequence by using principal component analysis (PCA) and discrete Fourier transform (DFT) algorithms, and finally calculates and compares the processed signal-to-noise ratio (SNR). The results show that Barker code modulated thermal wave infrared detection can detect the debonding defects of GFRP laminates. Among them, the detection effect of 13-bit Barker coded modulation excitation is better, and the image processed by DFT has better recognition effect.