STP1230: Fatigue and Fracture of the 767 Graphite Torsion Spring

    Bliss, RW
    Senior research engineer and technical program manager, Alliant Techsystems, Bacchus Works, Magna, UT

    Wheeler, DL
    Senior research engineer and technical program manager, Alliant Techsystems, Bacchus Works, Magna, UT

    Maguire, R
    Principal engineer, Boeing Commercial Aircraft Company, Seattle, WA

    Pages: 13    Published: Jan 1995


    Abstract

    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.

    Keywords:

    graphite torsion spring, high-temperature epoxy matrix, translaminar fracture, tow waves, strength, fatigue life


    Paper ID: STP14028S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP14028S


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