STP467

    Crack Initiation at Stress Concentrations as Influenced by Prior Local Plasticity

    Published: Jan 1970


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    Abstract

    The effects of high loads on crack initiation lives of notched specimens were quantitatively assessed from an analysis of local behavior at the stress concentration. Local cyclic stresses were determined by a simulation technique involving unnotched specimens and agreed well with experimental local stresses. Unnotched specimens were fatigue tested under stress sequences equal to the local stresses in notched specimens, and test results were used as estimates of crack initiation lives for the notched specimens. These estimates reflected the general effects of prior local plasticity on crack initiation behavior at a stress concentration but were consistently shorter than experimentally determined crack initiation lives. This discrepancy was attributed to the large difference in volume of highly stressed material for the notched and unnotched specimens.

    Keywords:

    fatigue (materials), notch strength, crack initiation, loads (forces), stresses, residual stress, plastic properties, simulation, stress concentration


    Author Information:

    Crews, JH
    Aerospace technologist, National Aeronautics and Space Administration, Langley Research Center, Hampton, Va.


    Paper ID: STP26838S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP26838S


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