STP636: Fatigue Behavior of Composites Under Different Loading Modes

    Sims, DF
    Research project engineer, Bell Helicopter TextronSouthwest Research Institute, Fort WorthSan Antonio, TexTex

    Brogdon, VH
    Research analysis engineer, Bell Helicopter Textron, Fort Worth, Tex

    Pages: 21    Published: Jan 1977


    Abstract

    The fatigue characteristics of S-glass/epoxy (Scoth-ply SP-250-SF1) and graphite/epoxy (Rigidite 5209-T300) laminates were studied for tension and shear loading. Emphasis was placed on fiber orientations where the matrix contribution to fatigue strength is significant. A general regression curve was used for data analysis, and a two-parameter Weibull model was used for reliability studies. An existing plane-stress macroscopic failure theory for static strength was extended to predict fatigue strength. It was found that the fatigue failure theory provides a conservative approach to first-ply failure which should be useful for preliminary design of composite structures.

    Keywords:

    composite materials, fatigue (materials), shear tests, tension tests, fiberglass-reinforced plastics, graphite composites, epoxy laminates, regression analysis, reliability


    Paper ID: STP27978S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP27978S


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