STP1128: Ultrasonic Detection of Fatigue Damage in Glass-Epoxy Composite Flywheels

    Simpson, WA
    Senior research staff member and consultant, Oak Ridge National Laboratory, Oak Ridge, TN

    McClung, RW
    Senior research staff member and consultant, Oak Ridge National Laboratory, Oak Ridge, TN

    Pages: 21    Published: Jan 1992


    Abstract

    Energy storage flywheels fabricated of S2 glass-epoxy composite were studied to determine the behavior of the ultrasonic properties as a function of strain history and to identify possible predictors of incipient failure. Tension specimens of the flywheel material were loaded uniaxially, and the ultrasonic properties (that is, the shear and longitudinal wave velocities and the attenuation) were measured as a function of strain. Finished flywheels were similarly tested at various stages during cyclic spin testing; in addition, the polar backscattering intensity as a function of fatigue cycle was recorded. The velocities are excellent indicators of the maximum strain incurred at each point of the flywheel, and the attenuation delineates the region in which the stress is high enough to initiate microcracking in the matrix.

    Keywords:

    composite materials, glass-epoxy composites, nondestructive testing, ultrasonics, velocity, attenuation, strain, fatigue


    Paper ID: STP14576S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP14576S


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