STP677

    Path Dependence of J in Three Numerical Examples

    Published: Jan 1979


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    Abstract

    Three cracked geometries are studied with the aid of a new finite element model. The procedure employs a variable singularity at the crack tip that tracks changes in the material response during the loading process. Two of the problems are tension-loaded center-crack panels and the other is a three-point bend specimen. Results usually agree quite well with other numerical and analytical analyses. An exception is the finding that J is path dependent as a substantial plastic zone develops. Credible J values are obtained near the crack tip and J shows a significant increase as the radius of J path increases over two orders of magnitude. Far field J exhibits agreement with analyses whose method implements the deformation theory of plasticity. However, this particular model employs incremental theory. Incremental and deformation theories are identical provided the stresses exhibit proportionality. This proportionality is found in the far field stresses but not near the tip. Consistent with the concept of nonproportionality, the path dependence of J is linked to the relative resharpening of the crack flank near the tip in center-crack specimens.

    Keywords:

    crack propagation, deformation, plasticity, J-integral


    Author Information:

    Karabin, ME
    Graduate assistant and professor, Carnegie Institute of Technology, Carnegie-Mellon UniversityWestinghouse Electric Corporation, PittsburghMadison, Pa.Pa.

    Swedlow, JL
    Graduate assistant and professor, Carnegie Institute of Technology, Carnegie-Mellon UniversityWestinghouse Electric Corporation, PittsburghMadison, Pa.Pa.


    Paper ID: STP34938S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP34938S


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