Three-Dimensional Analyses of Crack-Tip-Opening Angles and δ5-Resistance Curves for 2024-T351 Aluminum Alloy

    Published: Jan 2002

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    The objective of this paper was to investigate the fracture behavior of compact and middle-crack tension specimens made of 6.35 mm thick 2024-T351 aluminum alloy. Tests were conducted on compact tension, C(T), specimens ranging in width from 51 to 152 mm and on middle-crack tension, M(T), specimens ranging in width from 76 to 1016 mm. Most of the M(T) specimens were allowed to buckle during the fracture tests. Three-dimensional, elastic-plastic, finite-element analyses (FEA) using the WARP3D code with straight-front cracks were used to show transferability of the critical crack-tip-opening angle (CTOA) fracture criterion from small laboratory specimens, such as the C(T) specimen to large M(T) specimens. A single value of critical CTOA (Ψc = 6.35°) was determined from the FEA (with a straight-crack front) by matching the average failure load for the 152 mm C(T) specimens. CTOA analyses were then conducted on the various width C(T) and M(T) specimens. The WARP3D analyses with the critical CTOA predicted the experimental failure loads within ±3% for all specimens. The δ5-resistance curves from the analyses of the C(T) and M(T) specimens were nearly identical up to the maximum load. Beyond maximum load, the δ5-resistance curves for the C(T) specimens began to deviate rapidly; whereas, the δ5-resistance curves for the M(T) specimens only deviated slightly.


    CTOA, CTOD, cracks, elastic-plastic fracture, δ, 5, resistance curve

    Author Information:

    James, MA
    National Research Council research associate and senior scientist, NASA Langley Research Center, Hampton, VA

    Newman, JC
    Analytical Services and Materials, Inc., Hampton, VA

    Johnston, WM
    Analytical Services and Materials, Inc., Hampton, VA

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP10592S

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