STP803V1: A Criterion Based on Crack-Tip Energy Dissipation in Plane-Strain Crack Growth Under Large-Scale Yielding

    Saka, M
    Tohoku University, Sendai,

    Shoji, T
    Research Institute for Strength and Fracture of Materials, Tohoku University, Sendai,

    Takahashi, H
    Research Institute for Strength and Fracture of Materials, Tohoku University, Sendai,

    Abé, H
    Tohoku University, Sendai,

    Pages: 29    Published: Jan 1983


    Abstract

    In order to assess the proper resistance of elastic-plastic materials for stable crack growth in Mode I under plane-strain conditions with large-scale yielding, a fracture criterion based on a rate of the crack-tip energy dissipation with crack extension was proposed. The criterion can be expressed as TW = (TW)c, where TW is a newly developed tearing parameter defined as TW = (1/R)(E/σ02)(dp/da). The parameter TW is a dimensionless representation of the increment of plastic work done, dp/da, in a circular region of characteristic radius R at the growing crack tip, and TW is related directly as the amplitude to the singularity field at a growing crack tip.

    A procedure of experimental determination of (TW)c was described, where the crack-tip energy dissipation, Wp, was evaluated by means of the recrystallization-etch technique, and the width of recrystallized region observed parallel to the growing crack surface was used as the characteristic radius R. With special reference to a nonlinearity of the J-resistance curve for a wide range of crack extension, a conventional estimation procedure of the rate of crack-tip energy dissipation in terms of γ[=(½)β2σ02R(TW)c] was also described.

    Furthermore, the TW criterion was verified experimentally and numerically in comparison with other candidate tearing parameters TJ[=(E/σ02)(dJ/da)] and Tδ[=(E/σ0) (dδ/da)]. A significant superiority of TW over TJ and Tδ [crack-opening angle (COA)] was emphasized as a characterizing parameter for crack growth. It was shown that the critical value of TW during crack growth was not affected by specimen size, side groove depth, and an amount of crack extension.

    Keywords:

    ductile fracture, fracture criterion, stable crack growth, crack-tip energy dissipation, tearing parameter, intense strain region, recrystallization-etch technique, finite-element analysis, resistance curve, crack-opening angle, J-integral, elastic-plastic fracture


    Paper ID: STP37291S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP37291S


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