STP803V1

    Effects of Thickness on J-Integral in Structures

    Published: Jan 1983


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    Abstract

    The distribution of the Ĵ-integral, an extension of the J-integral, is calculated along the crack front of compact specimens of varying thicknesses by a three-dimensional elastic-plastic finite-element method. The Ĵ-integral takes the maximum value at the midthickness and smaller values near the plate surfaces, and the Ĵ-value at the midthickness coincides with the J-value determined from the computed load versus load-line displacement curve by using the Merkle-Corten formula. These results explain why the plane-strain fracture toughness value JIc can be experimentally determined by using specimens of moderate thickness.

    To avoid the expense of three-dimensional computations, an empirical formula based on a two-dimensional finite-element method is proposed to determine the J-value which coincides with the Ĵ-value at midthickness in a cracked structure. Experimental results on compact specimens of 304 and 4340 steels and also on rotating disks of 4340 steel indicate that the onset of crack growth in a structure with finite thickness can be estimated by using the empirical formula and the JIc-value of the compact specimen.

    Keywords:

    elastic-plastic fracture, structure, compact specimen, rotating disk, J-integral, finite-element method


    Author Information:

    Sakata, M
    Professor, associate professor, and research associate, Department of Physical Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo,

    Aoki, S
    Professor, associate professor, and research associate, Department of Physical Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo,

    Kishimoto, K
    Professor, associate professor, and research associate, Department of Physical Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo,

    Kanzawa, M
    Research engineers, Research Laboratory, Ebara Corp., Fujisawa, Kanagawa,

    Ogure, N
    Research engineers, Research Laboratory, Ebara Corp., Fujisawa, Kanagawa,


    Paper ID: STP37308S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP37308S


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