STP1012

    Fracture of Pressurized Composite Cylinders with a High Strain-to-Failure Matrix System

    Published: Jan 1989


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    Abstract

    An experimental and analytical investigation was conducted to examine the fracture behavior of pressurized graphite/epoxy cylinders and coupons that utilize a high strain-to-failure matrix system. The material system is a five-harness satin-weave cloth made of Hercules AS4 fiber impregnated with American Cyanamid's CYCOM 907 epoxy. Tests were performed on standard tensile coupons to determine the elastic constants of the material and the notched and unnotched fracture characteristics of a quasi-isotropic (0,45)s laminate of this material system. Two notch types, holes and slits, were examined, and existing failure criteria were explored as means to extrapolate these coupon data to the prediction of the failure pressures of axially slit cylinders, which were also tested. The fracture characteristics of this composite system were compared to a baseline system with Hercules 3501-6 epoxy. In the laminates using the "tough" matrix system, delamination was not a significant damage mode. Previous work had shown localized delamination in the 3501-6 laminates. However, both the coupon tests and the cylinder tests indicate that this high strain-to-failure matrix system is more notch sensitive than the baseline epoxy system with the relatively brittle 3501-6 matrix.

    Keywords:

    composite materials, notched strength, pressurized cylinders, fracture, “tough” matrix systems


    Author Information:

    Saeger, KJ
    Research assistant and associate professor, Technology Laboratory for Advanced Composites, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Mass.

    Lagace, PA
    Research assistant and associate professor, Technology Laboratory for Advanced Composites, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Mass.


    Paper ID: STP10423S

    Committee/Subcommittee: D30.05

    DOI: 10.1520/STP10423S


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