Characterization of sub-surface wrinkles within a laminated composite using a novel phased array ultrasonic scanning technique incorporating a portable nozzle and robotic arm.


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Due to their superior strength to weight ratio as compared to metals, the use of laminated composites is growing in the aerospace, automotive and energy sectors. This increased performance is severely compromised by the presence of out-of-plane wrinkles, a manufacturing defect that occurs in thick complex curvature composite stacks. This thesis presents an ultrasound scanning technique utilizing a novel phased array approach to detect out-of-plane wrinkles and, unlike previous literature results, quantify wrinkle dimensions. Multiple nozzle designs are provided for phased array probes to improve portability and scanning setup. A robotic system is presented that incorporates the novel scanning technique, which allows inspection of parts with non-planar geometries. The measured quantities are validated using 𝜇-CT scans, and results are provided that show average relative errors of 8.33%, 22.79% and 9.72% for, respectively, wrinkle height, width, and intensity corresponding to an average absolute error of, respectively, 0.057mm, 1.59mm and 4.7 × 10−3 .