STP736: Fatigue and Its Relationship to End-Use Performance

    Loveless, HS
    Research associatematerials research managersenior process engineer, PPG Industries Inc., Fiber Glass Research CenterGlastron Boat CompanyHercules Inc., PittsburghAustinDe Soto, Pa.Tex.Kans.

    Ingle, LR
    Research associatematerials research managersenior process engineer, PPG Industries Inc., Fiber Glass Research CenterGlastron Boat CompanyHercules Inc., PittsburghAustinDe Soto, Pa.Tex.Kans.

    Gerrard, CE
    Research associatematerials research managersenior process engineer, PPG Industries Inc., Fiber Glass Research CenterGlastron Boat CompanyHercules Inc., PittsburghAustinDe Soto, Pa.Tex.Kans.

    Pages: 13    Published: Jan 1981


    Abstract

    This paper describes two types of fatigue tests, cyclic and static, and their abilities to predict the long-term behavior of glass-fiber reinforced plastics in a marine and an electrical utility application.

    Employing a modification of the existing ASTM Test for Flexural Fatigue of Plastics by Constant-Amplitude-of-Force (D671-78), a procedure was devised for differentiating styrene-suppressed polyester orthophthalic resin systems used as secondary bonding media for the encapsulation of wooden stringers to the hull section of marine craft. Using specimens machined from overlapped panels processed with various resin systems, the laboratory test employs a fixed stress at the overlap of 13.8 MPa (2000 psi). The resistance of the overlap to the completely reversed bending load is measured in terms of the number of cycles endured to failure by the overlap. Correlation of these laboratory measurements with actual service tests of pleasure craft in the Gulf of Mexico has been excellent, thus attesting to the validity and usefulness of such data for predicting the fatigue resistance of the bond between the stringers and hull section of the boat under a fatigue environment imposed by choppy waters in end use.

    The paper concludes with a discussion of the Prot method for the prediction of the long-term tensile strength of plastics under static (fatigue) loading, together with an analysis of an electrical cable application of reinforced plastics, based upon the Prot test and elastic modulus considerations.

    Keywords:

    orthophthalic, reinforced plastics, composite, styrene-suppressed resins, styrene emission, encapsulation, hull stringers, chopped-strand mat, secondary bonding, dynamic, overlapped, ACSR cable, power transmission, aluminum conductors, core, steel-reinforced, cyclic fatigue, static fatigue, long-term strength, elastic modulus, RP pultruded rod, tower-to-tower, drop-cable, Prot tests, endurance limit, Wohler method, creep-rupture, load-bearing, laminate, end use, S-N curve, specimen, testing, polyester, chemistry


    Paper ID: STP27666S

    Committee/Subcommittee: D20.10

    DOI: 10.1520/STP27666S


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