STP945

    Application of the VR Resistance Curve Method to Fracture of Various Crack Configurations

    Published: Jan 1988


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    Abstract

    A fracture resistance curve method based on the crack-tip-opening displacement (VR) for a “stationary” crack has been previously developed to characterize stable crack growth and instability behavior of cracked metallic materials. In this study, the VR-curve method has been applied to various crack configurations made of 2024-T351 and 7075-T651 aluminum alloys. Relationships between VR, crack length, specimen width, and tensile properties have been derived from the Dugdale or strip-yield model. For arbitrarily cracked configurations, two methods of analysis, namely, the boundary-integral equation and finite-element methods, have been developed herein to analyze the strip-yield model. These analyses and the VR-curve determined from compact specimens were used to predict stable crack growth and maximum load behavior for several crack configurations made of two aluminum alloys.

    The VR-curve method was found to correlate stable crack growth data from compact specimens up to maximum load. After the maximum load was reached in a test, the values of VR remained nearly constant for each specimen but the constant value was dependent upon specimen type, crack length, and width. Predicted stable crack growth and maximum load behavior for compact, middle-crack and single-edge-crack tension specimens agreed within about 5% of experimental failure loads, whereas predictions made on three-hole-crack tension specimens were within about 15% of experimental failure loads.

    Keywords:

    fracture, cracks, plastic deformation, stress analysis, displacement


    Author Information:

    Newman, JC
    Senior scientist, NASA Langley Research Center, Hampton, VA

    McNeill, SR
    Graduate student and assistant professor, University of South Carolina, Columbia, SC

    Sutton, MA
    Graduate student and assistant professor, University of South Carolina, Columbia, SC


    Paper ID: STP23236S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP23236S


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