Nondestructive evaluation of out-of-plane wrinkles within woven carbon fiber reinforced plastics (CFRP) using ultrasonic detection.


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In the automotive and aerospace industries composite materials are heavily utilized as they provide a great strength to weight ratio relative to their metallic counterparts. A drawback is they require complex manufacturing processes, and the final part performance is sensitive to internal defects. Of focus in the present study are out-of-plane wrinkles, specifically those not identifiable by visual inspection. A methodology is presented to manufacture composite laminates with intentional wrinkle defects requiring a multistage fabrication process. The manufactured parts are inspected using ultrasonic immersion scanning with full waveform capture. An automated methodology is presented in this thesis to track the wrinkle within a single lamina across the scan area resulting in a 3D plot of the wrinkle. The ultrasound data was aligned with 3D microscopy data resulting in average relative errors over all sample regions studied for the height, width, and intensity of the wrinkle of, respectively, 4.9%, 4.5% and 6.0%, with average absolute errors were 0.037 mm, 0.47 mm and 0.002, respectively.



Carbon fiber. Wrinkles. Out-of-plane wrinkles. Ultrasound.