STP1323

    Characterizing Crack Growth in Thin Aluminum Panels Under Tension-Torsion Loading Using Three-Dimensional Digital Image Correlation

    Published: Jan 2001


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    Abstract

    The enclosed work was performed to determine whether a critical crack opening displacement (COD) criterion can be used to predict the stable crack growth behavior of thin, 2024-T3 aluminum fracture specimens experiencing tension and torsion loading. Due to the complexity of the large deformations that occur near the crack tip in a single edge-cracked specimen under torsion loading, a state of the art three-dimensional computer vision system was developed and employed to make the three-dimensional vector displacement measurements required to determine COD. Results from the experimental program indicate that the three-dimensional surface profile and deformation measurement system was fully capable of making the required measurements, even in the presence of large, out-of-plane displacements and surface strains that occurred during the tension-torsion loading process. Specifically, the measurements show that (a) critical COD for tension-torsion loading is constant during crack growth, (b) COD is approximately 8% larger than observed for in-plane tension-shear and (c) the surface strain fields during crack growth are quite complex due to the coupling of out-of-plane displacements and in-plane surface strains.

    Keywords:

    mixed mode fracture experiments, tension-torsion loading, three-dimensional digital image correlation, non-contacting measurements, crack opening displacement


    Author Information:

    Helm, J. D.
    Chief Engineer, Correlated Solutions, Inc., Columbia, SC

    Sutton, M. A.
    Professor and former graduate student, University of South Carolina, Columbia, SC

    Boone, M. L.
    Professor and former graduate student, University of South Carolina, Columbia, SC


    Paper ID: STP42138S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP42138S


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