STP677

    Description of Stable and Unstable Crack Growth in the Elastic Plastic Regime in Terms of Jr Resistance Curves

    Published: Jan 1979


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    Abstract

    A simple estimate is made of the elastic energy release rate, I, available from an elastic-plastic cracked component in terms of G and collapse load. I may be significantly greater than G from linear elastic behavior. A crack growth resistance curve is measured in terms of a J-like quantity, Jr, that is related to the plastic work absorbed by a geometry dependent factor, η. The increment of elastic energy is compared to the increment of plastic work at constant displacement to predict the possibility of stable or unstable crack growth. Effects of machine compliance are included. Some recent results on instability, test piece size restrictions, and conventional J crack growth curves are recovered as a special case. Illustrative examples are given based on estimates of I and Jr curves measured on a low-strength structural steel for mixed mode or flat fracture with ductile micromechanism.

    Keywords:

    resistance curves, instability, J-contour-integral, slow crack growth, mechanical test methods, fatigue (materials), crack propagation


    Author Information:

    Turner, CE
    Professor, Imperial College, London,


    Paper ID: STP34939S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP34939S


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