STP982

    Overview of Crack Closure at Near-Threshold Fatigue Crack Growth Levels

    Published: Jan 1988


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    Abstract

    The effects of microstructure, environment, loading condition, and crack size on near-threshold fatigue crack growth rate properties are briefly reviewed. It was found that the concept of crack closure could generally be used to explain these effects. Furthermore, structural materials with superior fatigue threshold resistance can be developed by promoting crack closure through microstructural control.

    Realizing the importance of crack closure at threshold levels, crack closure measurements need to be standardized. Particularly, the relationship between far-field and near-tip crack closure measurements has to be investigated. With a rapid progress in experimental measurements and analytical modeling of crack closure, it is our hope that in the near future fatigue life of structural materials can be more accurately predicted by incorporating crack closure models.

    Keywords:

    crack closure, near-threshold, fatigue crack propagation (growth), microstructure, environment, loading condition, crack size, temperature, yield strength, grain size, compressive loading, load ratio, oxides, roughness, plasticity, fluid pressure, phase transformation, dual phase steels, alloys, gas, hydrogen, helium, cryogenic temperature, small cracks, copper, aluminum


    Author Information:

    Liaw, PK
    Fellow engineer, Westinghouse R&D Center, Pittsburgh, PA


    Paper ID: STP27201S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP27201S


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