STP687: A Review and Assessment of the Stress-Intensity Factors for Surface Cracks

    Newman, JC
    Research engineer, NASA-Langley Research Center, Hampton, Va

    Pages: 31    Published: Jan 1979


    Abstract

    The stress-intensity factor solutions proposed for a surface crack in a finite plate subjected to uniform tension are reviewed. Fourteen different solutions for the stress-intensity factors are compared. These solutions have been obtained over the past 16 years using approximate analytical methods, experimental methods, and engineering estimates.

    The present paper assesses the accuracy of the various solutions by correlating fracture data on surface-cracked tension specimens made of a brittle epoxy material. Fracture of the epoxy material was characterized by a constant value of stress-intensity factor at failure. Thus, the correctness of the various solutions are judged by the variations in the stress-intensity factors at failure. The solutions were ranked in order of minimum standard deviation. The highest ranking solutions correlated 95 percent of data analyzed within ±10 percent, whereas, the lowest ranking solutions correlated 95 percent of data analyzed within ±20 percent. However, some solutions could be applied to all data considered, whereas, others were limited with respect to crack shapes and crack sizes that could be analyzed.

    Keywords:

    fracture properties, fracturing, mechanical properties, stresses, cracks, fatigue (materials), crack propagation


    Paper ID: STP35030S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP35030S


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