Strain localization and dynamic recrystallization in the ice–air aggregate: a numerical study

We performed numerical simulations on the microdynamics of ice with air inclusions as a second phase. Our aim was to investigate the rheological effects of air inclusions and explain the onset of dynamic recrystallization in the permeable firn. The simulations employ a full-field theory crystal plas...

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Bibliographic Details
Published in:The Cryosphere
Main Authors: F. Steinbach, P. D. Bons, A. Griera, D. Jansen, M.-G. Llorens, J. Roessiger, I. Weikusat
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2016
Subjects:
geo
Online Access:https://doi.org/10.5194/tc-10-3071-2016
http://www.the-cryosphere.net/10/3071/2016/tc-10-3071-2016.pdf
https://doaj.org/article/f3521a756f0e4a859475bb3894a55945
Description
Summary:We performed numerical simulations on the microdynamics of ice with air inclusions as a second phase. Our aim was to investigate the rheological effects of air inclusions and explain the onset of dynamic recrystallization in the permeable firn. The simulations employ a full-field theory crystal plasticity code coupled to codes simulating dynamic recrystallization processes and predict time-resolved microstructure evolution in terms of lattice orientations, strain distribution, grain sizes and grain-boundary network. Results show heterogeneous deformation throughout the simulations and indicate the importance of strain localization controlled by air inclusions. This strain localization gives rise to locally increased energies that drive dynamic recrystallization and induce heterogeneous microstructures that are coherent with natural firn microstructures from EPICA Dronning Maud Land ice coring site in Antarctica. We conclude that although overall strains and stresses in firn are low, strain localization associated with locally increased strain energies can explain the occurrence of dynamic recrystallization.