STP1371

    The Role of Temperature Rate Terms in Viscoplastic Modelling: Theory and Experiments

    Published: Jan 2000


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    Abstract

    To describe inelastic material behaviour under nonisothermal loading conditions on the base of a viscoplastic model it is not sufficient to use only temperature-dependent model parameters. Also the temperature rate in the evolution equations of the internal variables must be considered. To investigate the influence of the temperature rate, experiments should be defined in which the model response shows a remarkable dependence on the temperature rate. Such experiments could be performed on a coupled “two-bar system” under thermal and complex thermomechanical loading, respectively. Using a recently developed testing facility experiments with a coupled “two-bar system” are realized. This allows different temperature paths to be applied to the two bars which can be coupled to produce the same total strain throughout the experiment. At the same time, the sum of the forces of the two bars is controlled as a function of time. In addition it is possible to perform suitable thermomechanical experiments on an “one-bar system.” Here experiments with loading conditions similar to those observed at the “two-bar system” can be performed. The results show that temperature rate terms are necessary to model ratchetting effects correctly. Therefore, approaches taken from the literature were investigated and modified to achieve best agreement between modelling and experiment.

    Keywords:

    modelling, viscoplasticity, ratchetting, thermomechanical loading


    Author Information:

    Kühner, R
    Research ScientistGroup Leader, Institut für Materialforschung II, Karlsruhe,

    Aktaa, J
    Research ScientistGroup Leader, Institut für Materialforschung II, Karlsruhe,

    Angarita, L
    Research ScientistGroup Leader, Universität Karlsruhe, Institut für Werkstoffkunde I, Karlsruhe,

    Lang, K-H
    Research ScientistGroup Leader, Universität Karlsruhe, Institut für Werkstoffkunde I, Karlsruhe,


    Paper ID: STP15256S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP15256S


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