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Kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings

Although the energetics of grain boundaries are more or less understood, their mechanical description remains challenging primarily because of very fast dynamics in the atomic length scale. By contrast, granular dynamics are extraordinarily sluggish. In this study, two dimensional centripetal packin...

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Autores principales: Kishore, Raj, Das, Shreeja, Nussinov, Zohar, Sahu, Kisor K.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4887881/
https://www.ncbi.nlm.nih.gov/pubmed/27245111
http://dx.doi.org/10.1038/srep26968
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author Kishore, Raj
Das, Shreeja
Nussinov, Zohar
Sahu, Kisor K.
author_facet Kishore, Raj
Das, Shreeja
Nussinov, Zohar
Sahu, Kisor K.
author_sort Kishore, Raj
collection PubMed
description Although the energetics of grain boundaries are more or less understood, their mechanical description remains challenging primarily because of very fast dynamics in the atomic length scale. By contrast, granular dynamics are extraordinarily sluggish. In this study, two dimensional centripetal packings of macroscopic granular particles are employed to investigate the role of geometric aspects of grain boundary formation. Using a novel sampling scheme, the extensive configuration space is well represented by a few prominent structures. Our results suggest that cohesive effects “iron out” any disorder present and enforce a transition towards a “fixed point” basin associated with a universal high density jammed hexagonal structure. Two main conjectures are advanced: (i) the appearance of grain boundary like structures is the manifestation of the kinetic instabilities of the densification process and has its origin in the structural rearrangement and (ii) the departure from six-fold coordination in the final packing is bounded from above by a sixth of the angular dispersion present in the initial configuration. If similar predictive consequences are further developed for three dimensional cases, this may have far reaching consequences in many areas of science and technology.
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spelling pubmed-48878812016-06-09 Kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings Kishore, Raj Das, Shreeja Nussinov, Zohar Sahu, Kisor K. Sci Rep Article Although the energetics of grain boundaries are more or less understood, their mechanical description remains challenging primarily because of very fast dynamics in the atomic length scale. By contrast, granular dynamics are extraordinarily sluggish. In this study, two dimensional centripetal packings of macroscopic granular particles are employed to investigate the role of geometric aspects of grain boundary formation. Using a novel sampling scheme, the extensive configuration space is well represented by a few prominent structures. Our results suggest that cohesive effects “iron out” any disorder present and enforce a transition towards a “fixed point” basin associated with a universal high density jammed hexagonal structure. Two main conjectures are advanced: (i) the appearance of grain boundary like structures is the manifestation of the kinetic instabilities of the densification process and has its origin in the structural rearrangement and (ii) the departure from six-fold coordination in the final packing is bounded from above by a sixth of the angular dispersion present in the initial configuration. If similar predictive consequences are further developed for three dimensional cases, this may have far reaching consequences in many areas of science and technology. Nature Publishing Group 2016-06-01 /pmc/articles/PMC4887881/ /pubmed/27245111 http://dx.doi.org/10.1038/srep26968 Text en Copyright © 2016, Macmillan Publishers Limited http://creativecommons.org/licenses/by/4.0/ This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/
spellingShingle Article
Kishore, Raj
Das, Shreeja
Nussinov, Zohar
Sahu, Kisor K.
Kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings
title Kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings
title_full Kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings
title_fullStr Kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings
title_full_unstemmed Kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings
title_short Kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings
title_sort kinetic instability, symmetry breaking and role of geometric constraints on the upper bounds of disorder in two dimensional packings
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4887881/
https://www.ncbi.nlm.nih.gov/pubmed/27245111
http://dx.doi.org/10.1038/srep26968
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