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Evaluating Thermally Damaged Polyimide Insulated Wiring (MIL-W-81381) with UltrasoundA series of experiments to investigate the use of ultrasound for measuring wire insulation have been conducted. Initial laboratory tests were performed on MIL-W-81381/7,/12, and /21 aviation wire, a wire that has polyimide (Kapton Registered Trademark) layers for insulation. Samples of this wiring were exposed to 370C temperatures for different periods of time to induce a range of thermal damage. For each exposure, 12 samples of each gauge (12, 16, and 20 gauges) were processed. The velocity of the lowest order axisymmetric ultrasonic guided mode, a mode that is sensitive to the geometry and stiffness of the wire conductor and insulation, was measured. The phase velocity for the 20-gauge MIL-W-81381/7 wire had a baseline value of 3023 +/- 78 m/s. After exposure to the high temperatures, the wire's phase velocity rapidly increased, and reached an asymptotic value of 3598 +/- 20 m/s after 100 hours exposure. Similar behavior was measured for the 16 gauge MIL-W-81381/21 wire and 12 gauge MIL-W-81381/12 wire which had baseline values of 3225 +/- 22 m/s and 3403 +/- 33 m/s respectively, and reached asymptotic values of 3668 +/- 19 m/s, and 3679 +/- 42 m/s respectively. These measured velocity changes represent changes of 19, 14, and 8 percent respectively for the 20, 16, and 12 gauge wires. Finally, some results for a wire with an ethylene tetrafluoroethylene insulation are reported. Qualitatively similar behaviors are noted ultrasonically.
Document ID
20030014498
Acquisition Source
Langley Research Center
Document Type
Preprint (Draft being sent to journal)
Authors
Madaras, Eric I.
(NASA Langley Research Center Hampton, VA United States)
Anastasi, Robert F.
(Army Research Lab. Hampton, VA United States)
Date Acquired
September 7, 2013
Publication Date
January 1, 2002
Subject Category
Nonmetallic Materials
Meeting Information
Meeting: 6th Joint FAA/DOD/NASA Aging Aircraft Conference
Location: San Francisco, CA
Country: United States
Start Date: September 16, 2002
End Date: September 19, 2002
Sponsors: Federal Aviation Administration, NASA Headquarters, Department of Defense
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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