STP1359

    Further Studies on T*ε Integral for Curved Crack Growth

    Published: Jan 1999


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    Abstract

    T*ε integral values associated with stable, curved crack growth in biaxially loaded, fatigued precracked, 2024-T3 single edge notched (SEN) specimens were determined. The SEN specimens were loaded under combined Modes I and II and mimicked the flapping of a failed lap splice joint of a pressurized airplane fuselage. Most specimens were provided with a tear strap, which was either bonded, bonded and riveted, or integrally machined (machined pad-up) in the specimen. The stably growing crack curved and either penetrated or curved again upon hitting the tear strap. The displacement field, which was determined by Moiré interferometry as well as with finite element analysis, was used to directly determine the T*ε and T* integral values. These T*ε values agreed reasonably well with those determined by an elastic-plastic finite element modeling of the experiments. T* was identical to that obtained previously for pure Mode I crack extension while the T* integral oscillated about its null value. The results of this study suggest that T* could represent the resistance for locally selfsimilar crack growth and that a crack will curve in the direction of vanishing T*.

    Keywords:

    mixed-mode fracture, stable crack growth, Moiré interferometry, elastic-plastic finite element analysis, tear straps


    Author Information:

    Lam, PW
    University of Washington, Seattle, WA

    Kobayashi, AS
    University of Washington, Seattle, WA

    Atluri, SN
    University of California, Los Angeles, Center for Aerospace Research and Education, Los Angeles, CA

    Tan, PW
    Federal Aviation Administration, William J. Hughes Technical Center, Atlantic City International Airport, NJ


    Paper ID: STP14243S

    Committee/Subcommittee: E08.01

    DOI: 10.1520/STP14243S


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