Abstract:
The Atlantic Research Corporation has reduced the three-dimensional (3-D) braiding process to automated commercial practice. At braiding rates of four inches per minute for three to ten interlocked plies, real-time process monitoring and feedback becomes a necessity. The initial video inspection objectives included: (1) a video hardware suite capable of 360° flaw detection, (2) measurement of braids per inch, and (3) measurement of axial and circumferential fiber alignment. The system was designed to work without tracer fibers and to handle any fiber contrast and reflectivity. The video acquisition and processing hardware was to accommodate future capability upgrades through software-based enhancements, requiring minimal hardware changes.
The technical approach provided by Computer Sciences Corporation was to use a desk top computer based system with a commercially available frame grabber/video array processor. Three cameras provide 360° coverage and adjust for various mandrel diameters. Illumination symmetry obviates calculation of two 2-D Fourier transforms, normally required during homomorphic image enhancement. This image pre-processing step improves the pattern matching algorithm performance, which determines braids per inch and fiber alignment. Braid patterns extracted from the captured image are subsequently adjusted to compensate for individual lens focus and actual camera angle. The resulting robust monitoring system is transferable to 2-D braiding, weaving, and other textile processes.
Source: Proceedings of the 'NDE applied to Process Control of Composite Fabrication' - Conference, 4-5 Oct 1994 St. Louis, Missouri. Publisher and Organizer: Nondestructive Testing Information Analysis Center (NTIAC) Texas Research Institute Austin, Inc. Austin, Texas [http://www.ntiac.com] [Buying the Proceedings]
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