STP1343: Measurability of Crack Closure

    Pippan, R
    Vice director and research assistants, Erich-Schmid-Institut für Festkörperphysik der Österreichischen Akademie de Wissenschaften, Leoben,

    Riemelmoser, FO
    Vice director and research assistants, Erich-Schmid-Institut für Festkörperphysik der Österreichischen Akademie de Wissenschaften, Leoben,

    Bichler, C
    Vice director and research assistants, Erich-Schmid-Institut für Festkörperphysik der Österreichischen Akademie de Wissenschaften, Leoben,

    Pages: 16    Published: Jan 1999


    Abstract

    Crack closure can be measured either with compliance techniques or by means of crack propagation methods.

    Each of these methods has its own specific limitation. We have performed simulations to show that the results of the measurements with compliance technique near the tip depend strongly on the position of the displacement gages and that the compliance curves of the remote clip gages are often too insensitive to detect the near-crack-tip closure.

    Apart from the sensitivity of the various methods for measuring near-tip closure there are also problems in determining the effective stress intensity ranges from the load-displacement curves. The different procedures proposed in the literature are discussed, too. It will be shown that the measured stress intensity where the crack physically opens is the parameter which determines the effective stress intensity range. Only in the case of a minute number of contacts with a width very small in relation to the distance to the crack tip does the stress intensity factor, where the contacts open, underestimate the real acting effective stress intensity range at the tip.

    Keywords:

    crack closure measurement, compliance technique, plasticity-induced crack closure, asperity-induced crack closure


    Paper ID: STP15749S

    Committee/Subcommittee: E08.06

    DOI: 10.1520/STP15749S


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