Plasticity size effects in voided crystals

M.I. Hussein, Ulrik Borg, Christian Frithiof Niordson, V. S. Deshpande

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    The shear and equi-biaxial straining responses of periodic voided single crystals are analysed using discrete dislocation plasticity and a continuum strain gradient crystal plasticity theory. In the discrete dislocation formulation, the dislocations are all of edge character and are modelled as line singularities in an elastic material. The lattice resistance to dislocation motion, dislocation nucleation, dislocation interaction with obstacles and annihilation are incorporated through a set of constitutive rules. Over the range of length scales investigated, both the discrete dislocation and strain gradient plasticity formulations predict a negligible size effect under shear loading. By contrast, under equi-biaxial loading both plasticity formulations predict a strong size dependence with the flow strength approximately scaling inversely with the void spacing. Excellent agreement is obtained between predictions of the two formulations for all crystal types and void volume fractions considered when the material length scale in the non-local plasticity model is chosen to be 0.325 mu m (about 10 times the slip plane spacing in the discrete dislocation models).
    Original languageEnglish
    JournalJournal of the Mechanics and Physics of Solids
    Volume56
    Issue number1
    Pages (from-to)114-131
    ISSN0022-5096
    DOIs
    Publication statusPublished - 2008

    Keywords

    • Dislocations
    • Size effects
    • Voids
    • Plasticity
    • Computer simulation

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