STP700

    Cyclic Inelastic Deformation Aspects of Fatigue-Crack-Growth Analysis

    Published: Jan 1980


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    Abstract

    The objective of this paper is to examine the general utility of a J-based analysis of cyclic plasticity aspects in fatigue-crack growth. Preliminary analysis of data which indicates J may be appropriate is reviewed, and it is shown that these data represent a unique test case where cyclic plasticity aspects may be inconsequential. Details of the J-integral are elaborated in the sense of possible limitations to the usefulness of the deformation theory in applications to cyclic plasticity. The phenomenology of fatigue crack growth under variable amplitude loading is reviewed, and residual deformations and stresses at the crack tip and in the wake of the crack are identified as essential features of the history dependent flow process associated with crack growth. Each of these aspects is elaborated and discussed with regard to the use of a single characterizing parameter; first for stationary, then for growing cracks. It is observed and concluded that J controlled near field (JNF) must be used on a cycle-by-cycle basis if a J based analysis is to potentially account for cyclic plasticity. A number of crucial analytical and experimental tests of the ability of J (JNF) to adequately characterize these effects are enumerated. It is also concluded that the use of a single parameter J based analysis for fatigue-crack-growth assessment in structures subjected to variable amplitude loading may be tenuous.

    Keywords:

    J-integral, cyclic plasticity, J, near field, fatigue crack growth, deformation theory, fractures (materials), crack propagation


    Author Information:

    Leis, BN
    Principal and research scientist, Battelle Columbus Laboratories, Columbus, Ohio

    Zahoor, A
    Principal and research scientist, Battelle Columbus Laboratories, Columbus, Ohio


    Paper ID: STP36965S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP36965S


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