The Effects of the Cold Working Process and Interference Fit Bushings on the Fatigue Life of Polycarbonate Specimens with Holes.
Abstract
Aircraft transparencies must provide performance and durability at an acceptable cost to be considered for production. The most important performance factor is flight safety. In order to achieve flight safety from a structural standpoint, the transparency system must withstand loads associated with flight and with bird impact. Conventional transparencies are fastened to an aircraft using bolts, and the ability to withstand flight loads or bird impact is strongly dependent upon the condition of the bolt holes in the transparency. Fatigue loading results from flight, and transparencies are subject to cracking due to the stress concentration associated with the bolts holes. Bolt hole cracks have been found by inspecting service-aged F-111, F-16, and B-1 transparencies. Transparency bolt hole cracking results in a reduced life of the transparency as well as reduced birdstrike capability. Because of the problems associated with bolt hole cracking: improvements in the fatigue life of the transparency will reduce the number of transparencies that are removed for this cause. Also, since many aircraft transparencies are now refurbished one or more times, reducing or eliminating bolt hole cracking will increase the refurbishable life of aircraft transparencies. In addition, birdstrike protection will not be reduced. This program was conducted to investigate and refine cold working techniques and to investigate interference fit bushings. Results of this program show better than two orders of magnitude improved fatigue life with interference fit bushings over the baseline.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1997
- Accession Number
- ADA349453
Entities
People
- Daniel R. Bowman
- Marc A. Huelsman
Organizations
- University of Dayton