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Proceedings Paper

Stress failure vignettes: errors of 10,000, the help of Humpty-Dumpty, and others
Author(s): John W. Pepi
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Paper Abstract

In the latter part of the 1980’s, an all glass aircraft window, required for photography, was designed for 10,000 hours of life under extreme environments, consisting of high altitude thermal gradients and high pressure differential. Further, the window would need to survive its lifetime in the presence of airborne dust particles at high speed, runway sand and debris, hailstone impact, and frequent handling and cleaning conditions, the latter of which could cause scratches. Analysis showed a lifetime well in excess of 1,000,000 hours, but tests indicated failure times well below 1000 hours. The apparent disconnect was due to the presence of residual stress, heretofore not considered. Additionally, premature hailstone test failure required further assessment to ensure survivability. An extensive redesign resulted in the first ever FAA approval for glass window design in a passenger cabin.

Paper Details

Date Published: 13 November 2014
PDF: 12 pages
Proc. SPIE 9197, An Optical Believe It or Not: Key Lessons Learned III, 91970G (13 November 2014); doi: 10.1117/12.2066942
Show Author Affiliations
John W. Pepi, L-3 Communications IOS-SSG (United States)

Published in SPIE Proceedings Vol. 9197:
An Optical Believe It or Not: Key Lessons Learned III
Mark A. Kahan, Editor(s)

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