STP803V1: J-Integral Analysis of Surface Cracks in Pipeline Steel Plates

    King, RB
    Materials research engineers, physicist, and supervisory metallurgist, Fracture and Deformation Division, National Bureau of Standards, Boulder, Colo.

    Cheng, Y-w
    Materials research engineers, physicist, and supervisory metallurgist, Fracture and Deformation Division, National Bureau of Standards, Boulder, Colo.

    Read, DT
    Materials research engineers, physicist, and supervisory metallurgist, Fracture and Deformation Division, National Bureau of Standards, Boulder, Colo.

    McHenry, HI
    Materials research engineers, physicist, and supervisory metallurgist, Fracture and Deformation Division, National Bureau of Standards, Boulder, Colo.

    Pages: 14    Published: Jan 1983


    Abstract

    A capability for direct experimental evaluation of the J-integral in surface-cracked members under elastic-plastic deformation is useful for providing understanding of the driving force for fracture. In addition, such a capability makes it possible to evaluate analytical and numerical predictions of J. Experimental procedures have been developed for direct evaluation of J at the root of surface cracks from quantities measured at the specimen surfaces. These procedures rely on the assumption that the line J-integral around the root of a surface flaw is sufficiently path-independent for practical purposes. Arguments in favor of this assumption are made.

    Experimentally measured J-integral results are presented for specimens containing surface cracks. Several specimens of pipeline steel 16 mm thick and 75 to 100 mm wide, containing surface cracks varying in length from 31 to 48 mm and in depth from 5.6 to 10.5 mm, were loaded in tension, and the J-integral was evaluated. Plots of measured J as a function of applied stress show a parabolic dependence followed by a nonlinear region and a vertical asymptote at the stress corresponding to net section yield. The experimental results are used to evaluate a simplified line-spring model for predicting J, and the model results compare favorably with the experimental data.

    Keywords:

    cracks, elastic-plastic, fracture mechanics, J-integral, surface cracks, surface flaws


    Paper ID: STP37309S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP37309S


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