Automated Fiber Placement (AFP) machines can be susceptible to tow-tape defects such as gaps and overlaps. These can reduce strength between 7% and 32%. Automated inspection is not fully effective, and current AFP systems rely heavily on visual-based inspections of each ply layer to detect and correct these tape defects.

(a) Simplified diagram showing the operating principles of AFP systems. (b) Gaps appear as a higher temperature and cool more rapidly.

In a method developed at Langley, the latent heat of the item under fabrication is used to create a thermal image of a just-completed tape bond. The image is then analyzed to detect anomalies in real time. The defect data can be used in a feedback process to guide the bonding operation and tag the defect location for subsequent inspection.

Image processing is a key element of successfully implementing the process. The image process technique used not only reduces processing resources (such as CPU usage, memory, etc.), but also allows for a number of standard time-based analysis algorithms, typical of flash thermography, to be applied to the data (the reconstructed sequence).

NASA is actively seeking licensees to commercialize this technology. Please contact The Technology Gateway at This email address is being protected from spambots. You need JavaScript enabled to view it. or 757-864-1178 to initiate licensing discussions. Follow this link here  for more information.

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This article first appeared in the January, 2019 issue of Tech Briefs Magazine.

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