Negative linear compressibility : beyond the wine-rack model and towards engineering applications
Negative Linear Compressibility (NLC), where a material expands in a given direction when subjected to hydrostatic compression, is a rare elastic property that has received much attention recently, but has yet to be used in practical applications. What are the mechanisms responsible for this propert...
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ndltd-bl.uk-oai-ethos.bl.uk-7126022018-08-07T03:12:09ZNegative linear compressibility : beyond the wine-rack model and towards engineering applicationsBarnes, David LewisMarmier, Arnaud2017Negative Linear Compressibility (NLC), where a material expands in a given direction when subjected to hydrostatic compression, is a rare elastic property that has received much attention recently, but has yet to be used in practical applications. What are the mechanisms responsible for this property in crystals and man-made structures? Are all mechanisms somehow related to the wine-rack model? Can we find an even simpler and more fundamental elucidation of NLC? Following this mechanistic approach, can we then identify “engineering” materials with NLC? To answer these questions, I have used a combination of analytical modelling based on beam theory and finite element analysis, to investigate several structures. At first, I examine in great detail the standard wine-rack in 2D and equivalents in 3D and identify the aspect ratio (close to two) at which NLC is maximum. By adding spacers I demonstrate that a cross is not a necessary condition, and that simpler angle changes in chains are sufficient to generate NLC. Looking for materials with intersecting straight chains, “zig-zag” chains or quasi-helical structures, I find that carbon fibre mats, some extruded polymers and some woods exhibit NLC. Finally, I show that elliptical voids in 2D sheets can also generate NLC in a way related to the wine-rack. This thesis improves the understanding of the mechanism(s) responsible for NLC by proving that a wine-rack is not necessary. Perhaps more importantly it suggests that the property can be exploited in several relatively common materials.620.1Negative Linear Compressiblity Auxetic Materials NLCUniversity of Exeterhttp://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.712602http://hdl.handle.net/10871/27099Electronic Thesis or Dissertation |
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620.1 Negative Linear Compressiblity Auxetic Materials NLC |
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620.1 Negative Linear Compressiblity Auxetic Materials NLC Barnes, David Lewis Negative linear compressibility : beyond the wine-rack model and towards engineering applications |
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Negative Linear Compressibility (NLC), where a material expands in a given direction when subjected to hydrostatic compression, is a rare elastic property that has received much attention recently, but has yet to be used in practical applications. What are the mechanisms responsible for this property in crystals and man-made structures? Are all mechanisms somehow related to the wine-rack model? Can we find an even simpler and more fundamental elucidation of NLC? Following this mechanistic approach, can we then identify “engineering” materials with NLC? To answer these questions, I have used a combination of analytical modelling based on beam theory and finite element analysis, to investigate several structures. At first, I examine in great detail the standard wine-rack in 2D and equivalents in 3D and identify the aspect ratio (close to two) at which NLC is maximum. By adding spacers I demonstrate that a cross is not a necessary condition, and that simpler angle changes in chains are sufficient to generate NLC. Looking for materials with intersecting straight chains, “zig-zag” chains or quasi-helical structures, I find that carbon fibre mats, some extruded polymers and some woods exhibit NLC. Finally, I show that elliptical voids in 2D sheets can also generate NLC in a way related to the wine-rack. This thesis improves the understanding of the mechanism(s) responsible for NLC by proving that a wine-rack is not necessary. Perhaps more importantly it suggests that the property can be exploited in several relatively common materials. |
author2 |
Marmier, Arnaud |
author_facet |
Marmier, Arnaud Barnes, David Lewis |
author |
Barnes, David Lewis |
author_sort |
Barnes, David Lewis |
title |
Negative linear compressibility : beyond the wine-rack model and towards engineering applications |
title_short |
Negative linear compressibility : beyond the wine-rack model and towards engineering applications |
title_full |
Negative linear compressibility : beyond the wine-rack model and towards engineering applications |
title_fullStr |
Negative linear compressibility : beyond the wine-rack model and towards engineering applications |
title_full_unstemmed |
Negative linear compressibility : beyond the wine-rack model and towards engineering applications |
title_sort |
negative linear compressibility : beyond the wine-rack model and towards engineering applications |
publisher |
University of Exeter |
publishDate |
2017 |
url |
http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.712602 |
work_keys_str_mv |
AT barnesdavidlewis negativelinearcompressibilitybeyondthewinerackmodelandtowardsengineeringapplications |
_version_ |
1718718683173355520 |