SYMPOSIA PAPER Published: 01 January 1995

Fatigue and Fracture of the 767 Graphite Torsion Spring


The effect of fiber tow waves on the static strength and in-service fatigue life of the Hercules Graphite Torsion Spring used in the Boeing 767 airline is presented. A concise process overview is given. Process variables affecting tow wave formation are identified. The design of quality control specimens is presented. Pictures of tow waves preceding translaminar fractures are shown. The functional relationship of nested tow wave amplitude and length to the maximum strain is briefly reviewed. Tow wave strength and in-service fracture cycle data are fit to regression curves. The potential fatigue life of the springs is predicted. Finally, no effect of fatigue on spring rate and permanent set was found.

Author Information

Bliss, RW
Alliant Techsystems, Bacchus Works, Magna, UT
Wheeler, DL
Alliant Techsystems, Bacchus Works, Magna, UT
Maguire, R
Boeing Commercial Aircraft Company, Seattle, WA
Price: $25.00
Contact Sales
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Developed by Committee: D30
Pages: 427–439
DOI: 10.1520/STP14028S
ISBN-EB: 978-0-8031-5297-7
ISBN-13: 978-0-8031-2012-9