STP948

    A Fractographic Investigation of the Influence of Stacking Sequence on the Strength of Notched Laminated Composites

    Published: Jan 1987


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    Abstract

    A study of the fracture processes in T300/5208 notched laminated composites concentrated on characterizing the influences of laminate stacking sequence on the formation of notch-tip damage zones and the subsequent mode of fracture of each ply of the laminate. The results revealed that laminate notched strength varied considerably with both a specified set of ply fiber orientations as well as the order in which the specific plies were arranged in the laminate. The fractographic examinations identified differences in the laminate fracture process which are believed to be the primary contributor to the differences in notched strength. The twelve laminates exhibited varying degrees of notch sensitivity as a result of the ability of a laminate to develop “subcritical” damage in a manner that relieved the high stress concentration at the notch tip.

    The percent of laminate fracture by broken fibers was in direct correlation with the laminate notched strength. Laminates which were not characterized by damage zones containing major delaminations exhibited higher percentages of failure by broken fibers and higher notched strength. Conversely, when delaminations resulted in widespread ply uncoupling, relatively few plies of a laminate failed by broken fibers producing a weaker laminate.

    Keywords:

    composite, graphite/epoxy, notched strength, damage, fracture, delamination


    Author Information:

    Harris, CE
    Assistant professor, Texas A&M University, TX

    Morris, DH
    Professor, Virginia Polytechnic Institute and State University, Blacksburg, VA


    Paper ID: STP25617S

    Committee/Subcommittee: D30.05

    DOI: 10.1520/STP25617S


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