STP497: The Initiation and Growth of Fatigue Cracks in Filament Reinforced Aluminum Alloys

    Hancock, JR
    Principal metallurgist, Midwest Research Institute, Kansas City, Mo.

    Pages: 20    Published: Jan 1972


    Abstract

    The low cycle fatigue behavior of filamentary composites of beryllium/1235 aluminum, beryllium/6061 aluminum, and boron/7075 aluminum were compared. The effects of the strength and ductility of the filaments and matrix, and the role of interfaces on fatigue crack initiation and growth were evaluated to develop guidelines for the design of fatigue resistant composites. Generally, brittle filaments, a low yield strength ductile matrix, weak interfacial bonds, and a large modulus difference between constituents are the factors which lead to greater fatigue resistance in filament reinforced metals. The observed modes of fatigue crack growth confirmed the theoretical predictions of the effects of stress distribution at a crack tip at an interface and extended the applicability of these predictions to filamentary composites.

    Keywords:

    composite materials, filaments, aluminum, beryllium, boron, reinforcement (structures), filament wound materials, diffusion welding, fatigue (materials), crack initiation, crack propagation, ductility, brittleness, interfaces, binding strength, yield strength, stress concentration, cyclic loads


    Paper ID: STP27764S

    Committee/Subcommittee: D30.04

    DOI: 10.1520/STP27764S


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