Volume 19, Issue 3 (July 1997)

    The Wyoming Combined Loading Compression (CLC) Test Method


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    Based upon extensive experimental testing and analytical modeling of compression test methods at the University of Wyoming and elsewhere during the past several years, a specific procedure is recommended for obtaining representative axial compressive strength design values for continuous fiber composite materials. A specimen in the form of an untabbed, straight-sided strip of a [90/0]ns cross-ply composite laminate is tested in a newly developed Wyoming combined loading compression (CLC) test fixture. The standard specimen is 140-mm (5.50-in.) long, 12.7-mm (0.50-in.) wide, and of uniform but arbitrary thickness. This length produces a 12.7-mm (0.50-in.) gage section in the fixture. By increasing the torque applied to the fixture clamping bolts, the ratio of shear-loading to end-loading is readily increased as required to avoid end crushing of the untabbed cross-ply specimen. Typically, the required torque is low, in the range of 2.26 to 2.83 N-m (20 to 25 in.-lb). Classical (linear) lamination theory is adequate to calculate a “back-out factor,” which is used to determine the unidirectional ply axial strength. Using a Hercules AS4/3501-6 carbon/epoxy composite material, it is demonstrated that the axial compressive strength obtained is fully comparable to the stress at failure in the 0° plies of laminates of any general lay-up configuration, and also to that measured for unidirectional composites tested using special mini-sandwich and thickness-tapered test specimens.

    Author Information:

    Adams, DF
    Professor and Ph.D. candidate, University of Wyoming, Laramie, WY

    Welsh, JS
    Professor and Ph.D. candidate, University of Wyoming, Laramie, WY

    Stock #: CTR10023J

    ISSN: 0884-6804

    DOI: 10.1520/CTR10023J

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    Title The Wyoming Combined Loading Compression (CLC) Test Method
    Symposium , 0000-00-00
    Committee D30