STP803V1

    Estimates of the C* Parameter for Crack Growth in Creeping Materials

    Published: Jan 1983


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    Abstract

    This paper discusses methods of determining the creep equivalent of the J-contour integral termed C* for a cracked body subjected to creep deformation. It is shown that C* can be expressed in terms of a creep displacement rate, which can be measured either at the loading points, or locally across the crack plane and an appropriate nondimensional factor. It is found that this factor can be estimated from numerical calculations for a material undergoing power-law hardening plastic deformation or from approximate limit analysis techniques. With either approach the nondimensional factor is found to be dependent on specimen geometry and crack length but to be relatively insensitive to the creep stress index n.

    The form of expression developed for C* is particularly suitable when experimental measurements of displacement rate can be made since it enables C* to be determined with little knowledge of the creep properties of the material. Comparisons with experimental creep crack growth data have indicated that the approximate limit analysis estimates of C* are satisfactory for the most part.

    Keywords:

    creep crack growth, fracture mechanics, C, * parameter, limit analysis, numerical methods, elastic-plastic fracture


    Author Information:

    Smith, DJ
    Research assistant and reader, Mechanical Engineering Department, Imperial College of Science & Technology, London,

    Webster, GA
    Research assistant and reader, Mechanical Engineering Department, Imperial College of Science & Technology, London,


    Paper ID: STP37321S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP37321S


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