This paper discusses a 3D defect reconstruction technique based on A-scan and B-scan signals by utilizing immersion ultrasonic testing for nondestructive evaluation (NDE) of carbon-fiber-reinforced plastic (CFRP) panels. Ultrasonic testing results have relatively low resolution and poor imaging quality in anisotropic composites due to the speckle noise produced by the interference of backscattered signals. Thus, the structure of defects becomes one of the key features in distinguishing different kinds of defects such as cracking, foreign objects, and delaminations of CFRP panels. This developed technique will be able to provide NDE inspectors with more detailed information on defect depth, volume, and 3D structure, as well as help them make quick, accurate, and reliable decisions. Data for multiple cross-sections within the region of interest (ROI) were first reconstructed from the raw amplitude data obtained from ultrasonic B-scan signals. For each cross-section, the outline of the defect structure was constrained by C-scan image and A-scan signal thresholding techniques, improving the edge contrast of the defect area to the non-defect area. Then, a 3D matrix was generated base on the enhanced B-scan data sets. The results obtained demonstrated that this applied method can reconstruct 3D delamination structure in a CFRP panel and offer detailed information of defects in an ROI by restraining the noises effectively. We believe this technique can make the defect evaluation process much easier and more accurate, and it can be expected to be a novel method for the ultrasonic result enhancement.

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