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Original Date: 11/03/1996
Revision Date: 01/18/2007
Information : Calibrating Ultrasonic Delamination Testing
The Development Division at the Oak Ridge Y-12 Plant has had to create much of its design and analysis equipment to support the 25 years of high performance composites experience. One group of equipment is the Ultrasonic Test Equipment and software.
The Division needed to test for delamination flaws in high pressure work bottles for hydraulically operated rocket guidance systems. It had established through very elaborate studies that ultrasonic B and C-scans could accurately locate the flaws, but each of the different shapes of the prototype bottles being developed had different measurement characteristics. Since composites are not as mechanically well characterized as metallic structures, a method had to be developed to inspect the different shapes.
To address this problem, the Development Division created a simple calibration process for its ultrasonic measurement system. A prototype of each new shape is deliberately manufactured with precisely located delamination flaws. The flaws are simulated by inserting two 0.01-mm thick, circular Teflon shims between the layers of filament in the composite structure. The shims are positioned side by side to create a non-adhering air gap between the Teflon layers. The prototype is then tested on the ultrasonic test equipment. The test software enables the new shape to be characterized.
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