Stress heterogeneities in anisotropic materials - their effect on dislocation fields and post-deformational recrystallization

insights from combined experiments and numerical simulations of polycrystalline ice

Sandra Piazolo, Maurine Montagnat, Verity Borthwick, Lynn Evans, Albert Griera, Fanny Grennerat, Herve Moulinec, John Wheeler

    Research output: Contribution to conferenceAbstract

    Abstract

    We present a coupled experimental and modeling approach to better understand the role of stress field heterogeneities on deformation and post-deformational behavior in material with a high viscoplastic anisotropy e.g. polycrystalline ice. We investigate: (1) Effect of stress heterogeneities on deformation behavior and microstructural development and, (2) effect of such microstructures on post-deformational recrystallization. (1) Full-field elasto-viscoplastic modelling (CraFT) is used to predict the local stress and strain field during transient creep in a polycrystalline ice sample. Modeling input includes the experimental starting microstructure and a validated slip system dependent flow law. EBSD measurements on selected areas are used to estimate the local dislocation field utilizing the Weighted Burgers Vector (WBV) analysis. Areas of local stress concentration correlate with triple junctions and grain boundaries, originating from strain incompatibilities between differently oriented grains. In these areas, the WBV analysis shows a non-negligible c-axis component that must be related to resolved shear stress in a prismatic plane, coherent with the predicted elevated stress levels. The resultant defect structure is necessary for the formation of the observed kink bands which have a well-defined crystallographic character, lattice distortions and subgrain development. (2) The microstructures arising from (1) significantly affect post-deformational behavior. Combined post-deformational annealing experiments and numerical simulations using the microdynamic modeling platform ELLE, allow prediction of the local microstructural evolution taking recovery within grains, grain boundary migration and nucleation into account. Results from this study, can explain several of the observed features in natural ice, and help to refine large scale models.
    Original languageEnglish
    Pages1
    Number of pages1
    Publication statusPublished - 2014
    EventAmerican Geophysical Union Fall Meeting - San Francisco
    Duration: 15 Dec 201419 Dec 2014

    Conference

    ConferenceAmerican Geophysical Union Fall Meeting
    CitySan Francisco
    Period15/12/1419/12/14

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