Dynamic recrystallization during deformation of polycrystalline ice: Insights from numerical simulations

Maria Gema Llorens, Albert Griera, Florian Steinbach, Paul D. Bons, Enrique Gomez-Rivas, Daniela Jansen, Jens Roessiger, Ricardo A. Lebensohn, Ilka Weikusat

Research output: Contribution to journalArticleResearchpeer-review

21 Citations (Scopus)

Abstract

© 2016 The Author(s) Published by the Royal Society. All rights reserved. The flow of glaciers and polar ice sheets is controlled by the highly anisotropic rheology of ice crystals that have hexagonal symmetry (ice lh). To improve our knowledge of ice sheet dynamics, it is necessary to understand how dynamic recrystallization (DRX) controls ice microstructures and rheology at different boundary conditions that range from pure shear flattening at the top to simple shear near the base of the sheets. We present a series of two-dimensional numerical simulations that couple ice deformation with DRX of various intensities, paying special attention to the effect of boundary conditions. The simulations show how similar orientations of c-axis maxima with respect to the finite deformation direction develop regardless of the amount of DRX and applied boundary conditions. In pure shear this direction is parallel to the maximum compressional stress, while it rotates towards the shear direction in simple shear. This leads to strain hardening and increased activity of non-basal slip systems in pure shear and to strain softening in simple shear. Therefore, it is expected that ice is effectively weaker in the lower parts of the ice sheets than in the upper parts. Strain-rate localization occurs in all simulations, especially in simple shear cases. Recrystallization suppresses localization, which necessitates the activation of hard, non-basal slip systems.
Original languageEnglish
Article number20150346
JournalPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume375
Issue number2086
DOIs
Publication statusPublished - 13 Feb 2017

Keywords

  • Dynamic recrystallization
  • Ice microstructure
  • Ice rheology
  • Non-basal activity
  • Strain hardening

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