STP513

    A Study of Local Stresses Near Surface Flaws in Bending Fields

    Published: Jan 1972


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    Abstract

    A set of photoelastic experiments utilizing stress freezing and slicing techniques was conducted in order to estimate stress fields near naturally grown deep surface flaws in plates under approximately cylindrical bending fields. Geometries investigated ranged over crack depth to crack length ratios of approximately 0.25 to 0.45 and over crack depth to plate thickness ratios of approximately 0.35 to 0.45. Results were compared to an approximate theory devised by F. W. Smith [6]. In order to achieve a comparison consistent with linear elastic fracture mechanics, the effect of the experimental non-linear zone due to finite rotations very near the crack tip was minimized by extrapolating across it. The plastic zone correction in the Smith theory was neglected.

    Results indicated that the Smith theory will predict the proper order of magnitude of the stresses near the crack border both in the region of maximum crack penetration and where the crack border intersects the tensile surface of the plate. However, in all tests the predicted stresses were lower than the experimental stresses in the former region and higher than the experimental stresses in the latter region.

    Keywords:

    fractures (materials), cracking (fracturing), bending, slicing, stresses, analytic geometries, stress analysis, shear stress, cracks, elastic theory, yield strength


    Author Information:

    Marrs, GR
    Research engineer, Westinghouse Electric Corp., Bettis Atomic Power Laboratory, Steam Generator Facility, West Mifflin, Pa.

    Smith, CW
    Professor of Engineering Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Va.


    Paper ID: STP34111S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP34111S


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