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5. On the role of long range internal stresses on grain nucleation during discontinuous recrystallization

Author

Duval, Paul, Louchet, Francois, Weiss, Jerome, and Montagnat, Maurine

Subjects
Condensed Matter - Materials Science
Abstract

The essential role of long range elastic interactions in recrystallization is demonstrated using a simple analytical model: pileup rearrangements following absorption of leading dislocations by a dislocation-free embryo provides an additional driving force that results in a drastic decrease of both the nucleation critical radius and the saddle point energy. A very sharp transition is evidenced, at which the saddle point totally disappears and nucleation becomes spontaneous. This transition occurs for a well defined critical stress corresponding to both a critical density of geometrically necessary dislocations and a critical strain, without invoking any critical nucleus size that may be reached with the help of some dislocation microstructure instability. The present model is illustrated here by the case of polycrystalline ice, but may apply to other crystalline material with significant plastic anisotropy, as Zircaloy for instance., Comment: 7 pages, 3 figures

Published
2010

14. Disentangling creep and isothermal metamorphism during snow settlement with X-ray tomography.

Author

Bernard, Antoine, Hagenmuller, Pascal, Montagnat, Maurine, and Chambon, Guillaume

Subjects
CREEP (Materials), X-rays, TOMOGRAPHY, EULER characteristic, SURFACE area, GRAIN size
Abstract

Once fallen, snow settles due to the combined effects of metamorphism and deformation of the ice matrix under gravity. To understand how these coupled processes affect snow evolution, we performed oedometric compression tests and continuously monitored the snow microstructure with X-ray tomography. Centimetric samples with an initial density between 200 and 300 kg m−3 were followed during an initial sintering phase and under two different loads of 2.1 and 4.7 kPa at $-8^\circ$ C for ~1 week. The microstructure captured at a voxel size of 8.5 μm was characterized by density, specific surface area (SSA) and two metrics related to bond network, namely the Euler characteristic and the minimum cut surface. Load-induced creep of the ice matrix was observed only for sufficiently low values of initial density (<290 kg m−3 in our tests), and was shown to be associated to a significant increase of the number of bonds. Application of the load, however, did not affect the individual bond size nor the SSA, which appeared to be mainly controlled by isothermal metamorphism. The uniaxial compression did not induce any creation of anisotropy on the microstructural characteristics. Overall, our results show that, for the considered conditions, the deformation of the ice matrix mainly leads to a reduction of the pore space and an increase of the coordination number, while metamorphism mainly affects the grain and bond sizes. [ABSTRACT FROM AUTHOR]

Published
2023
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18. Texture characterization of some large hailstones with an automated technique

Author

Montagnat, Maurine, Bourcier, Mathieu, Philip, Armelle, Bons, Paul, Bauer, Catherine, Deconinck, Paul, Hereil, Pierre, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Centre d'Etudes de la Neige (CEN), Centre national de recherches météorologiques (CNRM), Météo France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Météo France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Eberhard Karls University of Tübingen, Department of Geosciences, Applied Mineralogy, Wilhelmstraße 56, 72074 Tübingen, Germany, Thiot ingénierie, Puybrun, Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), and Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen

Subjects
[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology
Abstract

International audience; Abstract Hailstone structures have been studied for over a century, but so far mainly by manual optical means. This paper presents new texture and microstructure data (i.e. crystal lattice orientations, grain sizes and shapes) measured with an Automatic Ice Texture Analyzer, which gives access to high spatial and angular resolutions. The hailstones show two main characteristics: (1) they are structured with several concentric layers composed of alternating fine equiaxed grains and coarse elongated and radially oriented grains, and (2) they show two texture types with c -axes oriented either parallel or perpendicular to the radial direction. Such textures are compared with the ones observed in lake S1 and S2 ices, respectively. The S1 texture type (with c -axes parallel to the columnar crystals that grew in the radial direction) may result from epitaxial growth from a polycrystalline embryo, while the S2 texture ( c -axes in the plane perpendicular to the column direction) may result from the growth from an embryo made of a few crystals with mainly one crystallographic orientation. Our novel high-resolution maps and measurements of both microstructure and texture may help to shed new light on the long-term discussion on the growth mechanisms of large hailstones.

Published
2021
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19. Influence of porosity on ice dynamic behavior as assessed by spalling tests

Author

Georges, David, Saletti, Dominique, Montagnat, Maurine, Forquin, Pascal, Hagenmuller, Pascal, Hébert, David, Rullier, Jean-Luc, Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Risques, Vulnérabilité des structures et comportement mécanique des matériaux (RV), Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Centre d'Etudes de la Neige (CEN), Centre national de recherches météorologiques (CNRM), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA)-Météo-France -Institut national des sciences de l'Univers (INSU - CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Université Grenoble Alpes (UGA), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA-CESTA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Météo France-Centre National de la Recherche Scientifique (CNRS), and Météo France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Météo France-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, 010504 meteorology & atmospheric sciences, Materials Science (miscellaneous), 02 engineering and technology, Split-Hopkinson pressure bar, Strain rate, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, Mechanics of Materials, Dynamic loading, Ultimate tensile strength, [SPI.MECA.MEMA]Engineering Sciences [physics]/Mechanics [physics.med-ph]/Mechanics of materials [physics.class-ph], Fracture (geology), Texture (crystalline), [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, Composite material, 0210 nano-technology, Porosity, 0105 earth and related environmental sciences
Abstract

The impact of ice on structures is a strong concern, in particular for aeronautical or space crafts that are strongly damaged by the impact of atmospheric ice, and more specifically by hailstones during hailstorms. During the impact, the hailstone is submitted to a complex loading including a strong dynamic tensile component that is responsible for its fragmentation and influences the mechanical loading transmitted to the impacted structure. However, up to now, very limited work were conducted on the tensile strength of ice under dynamic loading and the microstructure influence was out the scope of most studies. In particular the presence of porosity in ice as observed in hailstones is thought to significantly affect the ice mechanical response. The aim of this paper is to investigate the role of porosity on the tensile behavior of polycrystalline ice at high strain rates. To do so, spalling tests with a Hopkinson bar apparatus were conducted on microstructures characterized by porosities with two different pore size distributions. The dynamic tensile strength was computed by the use of the so-called Novikov formula and several indicators were used to assess the quality of each test. A whole set of high porosity samples was tested and additional tests were performed on low porosity ice, expanding the existing results in the literature. The fragmentation processes occuring during the spalling tests were observed by means of an ultra high speed camera and the influence of porosity on the main fracture planes was investigated by analysing post-spalling samples with an automatic ice texture analyser and X-ray tomography. Tensile strength is shown to increase with strain rate over the range $$24\,\hbox {s}^{-1}$$ to $$120\,\hbox {s}^{-1}$$ and to decrease with increasing porosity. The presence of large porosities in the high porosity samples appear to contribute preferentially to this strength decrease. Relevant observations concerning the detected cracks, the tortuosity of crack paths and the presence of porosities on the crack surfaces seem to validate the hypothesis of porosities playing a key role for crack initiation and propagation during ice fragmentation.

Published
2021
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23. Characterization of the texture of large hailstones

Author

Montagnat, Maurine, Bourcier, Mathieu, Philip, Armelle, Bons, Paul, Bauer, Catherine, Deconinck, Paul, Hereil, Pierre, Montagnat-Rentier, Maurine, Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP ), Université Grenoble Alpes (UGA), Department of Geosciences [Tübingen], Eberhard Karls Universität Tübingen = Eberhard Karls University of Tuebingen, and Thiot ingénierie, Puybrun

Subjects
[SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, [SDU.STU.GL] Sciences of the Universe [physics]/Earth Sciences/Glaciology
Abstract

Hailstone structures have been studied for over a century, but so far mainly by manual optical means. This paper presents new texture and microstructure data (i.e. crystal lattice orientations, grain sizes and shapes) measured with an Automatic Ice Texture Analyzer (AITA) which gives access to high spatial and angular resolutions. The hailstones show two main characteristics; (i) they are structured with several concentric layers composed of alternating fine equi-axed grains and coarse elongated and radially oriented grains, (ii) they show two texture types with c-axes oriented either parallel or perpendicular to 5 the radial direction. Such textures are compared with the ones observed in lake S1 and S2 ices, respectively. The S1 texture type (with c-axes parallel to the columnar crystals that grew in the radial direction) may result from epitaxial growth from a polycrystalline embryo, while S2 texture (c-axes in the plan perpendicular to the column direction) may result from the growth from an embryo made of large crystals with only one or few crystallographic orientations. Owing to these high resolution measurements of both microstructure and texture, we are able to come back to a long-term discussion concerning the growth 10 mechanisms of large hailstones and clarify the main processes at play.

Published
2020

30. What can we learn from ice collected in high mountain rockfall scars? Three examples from the Mont Blanc massif (France)

Author

Ravanel, Ludovic, Magnin, Florence, Guillet, Grégoire, Montagnat, Maurine, Preunkert, Susanne, Duvillard, P.A, Deline, Philip, Pallandre, François, Environnements, Dynamiques et Territoires de la Montagne (EDYTEM), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Institut de gestion des entreprises -USJ (IGE), Université Saint-Joseph de Beyrouth (USJ), Institut des Géosciences de l’Environnement (IGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Ecole nationale de ski et d'alpinisme, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Environnements, Dynamiques et Territoires de Montagne (EDYTEM), and Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[SDE.MCG]Environmental Sciences/Global Changes, [SDE]Environmental Sciences, [SDE.ES]Environmental Sciences/Environmental and Society, ComputingMilieux_MISCELLANEOUS
Abstract

International audience; The study of the ice (cryostructures, cryostratigraphy, types and age) that partly fills the fractures in rockwall permafrost is necessary to better understand the increasing frequency/volume of rockfalls in the high alpine rockwalls. Typically inaccessible, this ice is visible only when a rockfall occurs, exposing previously hidden ice. Over the past two years, the two largest rockfalls of the decade in the Mont Blanc massif and a smaller one allowed to start the documentation of the rockwall permafrost ice. This poster aims to present the three cases. Up to now, dating has been carried out for only one of the three cases. How to date permafrost ice? Dating ice cores from alpine glaciers has shown the wide time span covered by these, from a few decades to several thousand years. Several dating methods are available to quantify the age. Counting the annual layers, which proved to be effective, is widely used in the study of mountain glaciers but cannot be used for the internal ice of the permafrost since it does not present these annual layers. Structure of the ice in the scar of the Trident of Tacul rockfall scar shows nevertheless a series of layers. We will therefore use radionuclide dating to obtain the absolute age of the ice. So far, only one age is available for interstitial ice from permafrost-affected rockwall: the ice sampled from a felt block that is part of the deposit of the 150'000 m 3 rockfall that occurred in Feb. 2014 at Piz Kesch (Swiss Alps

Published
2019
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32. Investigation of a cold-based ice apron on a high-mountain permafrost rock wall using ice texture analysis and micro-14C dating: a case study of the Triangle du Tacul ice apron (Mont Blanc massif, France).

Author

Guillet, Grégoire, Preunkert, Susanne, Ravanel, Ludovic, Montagnat, Maurine, and Friedrich, Ronny

Subjects
PERMAFROST, CORE drilling, COLLOIDAL carbon, GLACIAL Epoch, TRIANGLES, ICE cores
Abstract

The current paper studies the dynamics and age of the Triangle du Tacul (TDT) ice apron, a massive ice volume lying on a steep high-mountain rock wall in the French side of the Mont-Blanc massif at an altitude close to 3640 m a.s.l. Three 60 cm long ice cores were drilled to bedrock (i.e. the rock wall) in 2018 and 2019 at the TDT ice apron. Texture (microstructure and lattice-preferred orientation, LPO) analyses were performed on one core. The two remaining cores were used for radiocarbon dating of the particulate organic carbon fraction (three samples in total). Microstructure and LPO do not substantially vary with along the axis of the ice core. Throughout the core, irregularly shaped grains, associated with strain-induced grain boundary migration and strong single maximum LPO, were observed. Measurements indicate that at the TDT ice deforms under a low strain-rate simple shear regime, with a shear plane parallel to the surface slope of the ice apron. Dynamic recrystallization stands out as the major mechanism for grain growth. Micro-radiocarbon dating indicates that the TDT ice becomes older with depth perpendicular to the ice surface. We observed ice ages older than 600 year BP and at the base of the lowest 30 cm older than 3000 years. [ABSTRACT FROM AUTHOR]

Published
2021
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35. Hétérogénéités de déformation et mécanismes de recristallisation. Cas de la glace '2D-1/2'

Author

Montagnat, Maurine, chauve, Thomas, Grennerat, Fanny, Georges, David, Vacher, Pierre, Castelnau, Olivier, Institut de gestion des entreprises -USJ (IGE), Université Saint-Joseph de Beyrouth (USJ), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Laboratoire SYstèmes et Matériaux pour la MEcatronique (SYMME), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry]), Laboratoire Procédés et Ingénierie en Mécanique et Matériaux (PIMM), Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-Centre National de la Recherche Scientifique (CNRS)-Arts et Métiers Sciences et Technologies, HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM), Conservatoire National des Arts et Métiers [CNAM] (CNAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), and Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[PHYS.MECA.MEMA]Physics [physics]/Mechanics [physics]/Mechanics of materials [physics.class-ph], Corrélation d'Images Numériques, [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology, Glace, ComputingMilieux_MISCELLANEOUS, Hétérogénéités de déformation, Recristallisation dynamique
Abstract

International audience

Published
2018

41. Dynamic Tensile Behavior Of Granular Ice Using The Spalling Test Technique

Author

Saletti, Dominique, Gouy, Victor, Montagnat, Maurine, Forquin, P., Risques, Vulnérabilité des structures et comportement mécanique des matériaux (RV ), Laboratoire sols, solides, structures - risques [Grenoble] (3SR ), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut des Géosciences de l’Environnement (IGE), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut de Recherche pour le Développement (IRD)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Risques, Vulnérabilité des structures et comportement mécanique des matériaux (RV), Laboratoire sols, solides, structures - risques [Grenoble] (3SR), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut National Polytechnique de Grenoble (INPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Institut de Recherche pour le Développement (IRD)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), and Saletti, Dominique

Subjects
spalling test, [SPI]Engineering Sciences [physics], [SPI] Engineering Sciences [physics], fracture, ice, strain-rate sensitivity, dynamic tensile strength, [SPI.MECA]Engineering Sciences [physics]/Mechanics [physics.med-ph], [SPI.MECA] Engineering Sciences [physics]/Mechanics [physics.med-ph]
Abstract

International audience; The behavior of granular ice has been widely investigated during the last decades. Nevertheless, the characterization of the mechanical response of ice subjected to dynamic loading still suffers from a lack of experimental observation. Dynamic experiments have already been conducted in compression mode using Kolsky bar setup. Regarding tension, the literature gives only approximated strength values and experimental observations and measurements cannot be found. This knowledge is essential to design structures that may experience ice impact. In this framework, this study aims at providing data of the maximal strength of granular ice subjected to dynamic tensile loading. The spalling test technique has been used and tensile loading has been applied at strain rates from 30 to 145 /s. The experimental results show that there is a strain rate dependence of the maximal strength of ice, evolving from 3 MPa to 15.4 MPa, respectively from 30 to 145 /s.

Published
2017

47. Un modèle de plasticité cristalline considérant le transport des dislocations géométriquement nécessaires sur les systèmes de glissement : application aux mono- et multi-cristaux de glace

Author

Le, Lu Tuan, chauve, Thomas, Bernacki, Marc, Berbenni, Stéphane, Montagnat, Maurine, Richeton, Thiebaud, Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux (LEM3), Université de Lorraine (UL)-École Nationale Supérieure d'Arts et Métiers (ENSAM), Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM)-Centre National de la Recherche Scientifique (CNRS), Centre de Mise en Forme des Matériaux (CEMEF), Centre National de la Recherche Scientifique (CNRS)-PSL Research University (PSL)-MINES ParisTech - École nationale supérieure des mines de Paris, Laboratoire de glaciologie et géophysique de l'environnement (LGGE), Observatoire des Sciences de l'Univers de Grenoble (OSUG), Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Joseph Fourier - Grenoble 1 (UJF)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA)-Centre National de la Recherche Scientifique (CNRS), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS)-Arts et Métiers Sciences et Technologies, HESAM Université (HESAM)-HESAM Université (HESAM), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (OSUG ), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national des sciences de l'Univers (INSU - CNRS)-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut national de recherche en sciences et technologies pour l'environnement et l'agriculture (IRSTEA)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])

Subjects
[SPI]Engineering Sciences [physics], ComputingMilieux_MISCELLANEOUS
Abstract

National audience

Published
2016

48. Evolution of the Texture along the EPICA Dome C Ice Core

Author

Durand, Gaël, Svensson, Anders, Persson, Asbjørn, Gagliardini, Olivier, Gillet-Chaulet, Fabien, Sjolte, Jesper, Montagnat, Maurine, and Dahl-Jensen, Dorthe

Subjects
EPICA Dome C ice core, anisotropy, texture, recrystallization processes
Abstract

I. Microphysical properties, deformation, texture and grain growth, New measurements of ice texture made along the EPICA Dome C ice core, together with a review of previous studies of fabric and microstructure, are presented. Mean grain size increases steadily with age, and so depth. However, sharp decreases are observed contemporary with each climatic termination. These sharp decreases are believed to be mainly driven by the change in dust content between glacial and interglacial periods. C-axes steadily clustered with depth toward a vertical single maximum. However, a sharp clustering of the fabric is observed during termination II (≈ 1750 m), suggesting the presence of shear in the upper part of the core. Moreover, below 2812 m, large variations of the fabric are observed from sample to sample. Migration recrystallization may affect the ice polycrystal for the lowest part of the core.

Published
2009

49. Recrystallization Processes in Granular Ice

Author

Montagnat, Maurine, Durand, Gaël, and Duval, Paul

Subjects
Fabrics, Dynamic recrystallization, Ice sheets, Microstructures
Abstract

I. Microphysical properties, deformation, texture and grain growth, Recrystallization mechanisms are known to accommodate the deformation as observed along ice cores. The three main processes are classically described as being, successively from the top of the cores, normal grain growth, rotation dynamic recrystallization and migration dynamic recrystallization. Recent observations on local mechanisms at the grain scale tend to question this description. This paper aims at presenting the basic knowledge about dynamic recrystallization processes in materials, with focus on the corresponding mechanisms occuring during deformation of granular ice, more particularly along ice cores. We stress the significance of the scale to consider when analysing the mechanisms, depending on the applications. In particular, we will demonstrate that dislocation substructures can develop locally, due to strong strain heterogeneities, without challenging the classical description that explains the evolution of average grain size and fabrics along ice cores.

Published
2009

50. Are Self-Organised Critical Dislocation Dynamics Relevant to Ice Sheet Flow?

Author

Louchet, François, Duval, Paul, Montagnat, Maurine, and Weiss, Jérôme

Subjects
ice sheets, rotation recrystallization, normal grain growth, critical dynamics, creep, dislocations, Hall-Petch law
Abstract

I. Microphysical properties, deformation, texture and grain growth, It was recently shown thai crystals (including ice) plastically deform in an intermittent manner in usual laboratory conditions. The present paper aims at discussing whether such self-organised critical dynamics still apply to polar ice sheet conditions. Field data suggest that grains should contain between zero and one dislocation moving at a time. However, this is nothing but an average estimate. Field data also show that strong back-stresses are present, collesponding to a significant density of potentially mobile dislocations. These findings, together with the very low loading level, are consistent with critical dislocation dynamics, in which collective motion events occur for a short time, followed by long periods of inactivity during which grain growth, rotation recrystallization and other recovery processes contribute to the reduction of the long range internal stress field. The stress and grain size dependencies of the strain rate are derived on this basis. The applicability of the Hall-Petch law is also discussed.

Published
2009

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