Molecular dynamics simulations of strained and defective carbon nanotubes

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Sammalkorpi, Maria
dc.date.accessioned 2012-02-13T13:10:33Z
dc.date.available 2012-02-13T13:10:33Z
dc.date.issued 2004-12-17
dc.identifier.isbn 951-22-7379-9
dc.identifier.issn 1455-0474
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2498
dc.description.abstract Carbon nanotubes are tubular molecules of pure carbon with typical diameters of 1 nm – 100 nm and lengths from 100 nm up to several cm. The nanotubes have outstanding electronical and mechanical properties which has resulted in remarkable scientific interest and in proporsals of various applications. For example, their ability to be either metals or semiconductors enables the usage of nanotubes as components of electronic devices, while excellent mechanical characteristics motivate the use of nanotubes as reinforcement agents in composite structures and in nanoelectromechanical devices. This thesis aims to contribute to the understanding of the mechanical properties of carbon nanotubes and it contains two parts. The first part concentrates on initially defect-free but strained nanotubes and on the deformations and defects induced by the strain. The employed methods are empirical and tight binding molecular dynamics simulations. As results the criteria for uniform and discontinuous buckling deformations are reported. In addition, defect formation and strain relaxation are discussed and the stability of various strained and deformed structures is assessed. The second part of the thesis evaluates defects as a means to improve the bulk mechanical properties of a nanotube sample. Defects, and irradiation as a method of inducing them, are proposed to improve mechanical load transfer between a nanotube and its surroundings. These proposals are verified by analytics and molecular dynamics simulations based on classical empirical potential. The load transfer between nanotubes is found to improve significantly in the presence of defects. This concept is extended to bundles of nanotubes where the improved tube-tube load transfer is predicted to increase shear and stiffen the bundle at moderate irradiation doses. The load transfer has great significance for reinforcement of polymer composites in which the nanotube bundles may act as reinforcement fibers. Furthermore, the mechanical degradation of individual tubes as a result of the defects is also assessed. Point defects have little effect on the axial stiffness of an individual tube but the tensile strength may decrease to a fraction of the strength for a perfect tube. Although individual tubes deteriorate in strength because of the defects, the results indicate that the overall mechanical properties of a nanotube sample can be significantly improved by imperfections in the structure of the tubes. en
dc.format.extent 58, [40]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.ispartofseries Helsinki University of Technology Laboratory of Computational Engineering publications. Report B en
dc.relation.ispartofseries 41 en
dc.relation.haspart Huhtala M., Kuronen A. and Kaski K., 2002. Carbon nanotube structures: molecular dynamics simulation at realistic limit. Computer Physics Communications 146, number 1, pages 30-37. [article1.pdf] © 2002 Elsevier Science. By permission.
dc.relation.haspart Huhtala M., Kuronen A. and Kaski K., 2002. Computational studies of carbon nanotube structures. Computer Physics Communications 147, numbers 1-2, pages 91-96. [article2.pdf] © 2002 Elsevier Science. By permission.
dc.relation.haspart Huhtala M., Kuronen A. and Kaski K., 2002. Carbon nanotubes under bending strain. In: Bernier P., Ajayan P., Iwasa Y. and Nikolaev P. (editors), Making Functional Materials with Nanotubes. Materials Research Society Symposium Proceedings, volume 706, pages 289-294. [article3.pdf] © 2002 Materials Research Society. By permission.
dc.relation.haspart Huhtala M., Krasheninnikov A. V., Aittoniemi J., Stuart S. J., Nordlund K. and Kaski K., 2004. Improved mechanical load transfer between shells of multiwalled carbon nanotubes. Physical Review B 70, 045404. [article4.pdf] © 2004 American Physical Society. By permission.
dc.relation.haspart Sammalkorpi M., Krasheninnikov A. V., Kuronen A., Nordlund K. and Kaski K., Mechanical properties of carbon nanotubes with vacancies and related defects. Physical Review B, accepted for publication. [article5.pdf] © 2004 American Physical Society. By permission.
dc.relation.haspart Sammalkorpi M., Krasheninnikov A. V., Kuronen A., Nordlund K. and Kaski K., Irradiation-induced stiffening of carbon nanotube bundles. Nuclear Instruments and Methods in Physics Research B, accepted for publication. [article6.pdf] © 2004 Elsevier Science. By permission.
dc.subject.other Physics en
dc.subject.other Electrical engineering en
dc.title Molecular dynamics simulations of strained and defective carbon nanotubes en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Electrical and Communications Engineering en
dc.contributor.department Sähkö- ja tietoliikennetekniikan osasto fi
dc.subject.keyword point defects en
dc.subject.keyword irradiation en
dc.subject.keyword nanocomposites en
dc.subject.keyword load transfer en
dc.subject.keyword molecular dynamics en
dc.subject.keyword nanotube en
dc.identifier.urn urn:nbn:fi:tkk-004617
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Laboratory of Computational Engineering en
dc.contributor.lab Laskennallisen tekniikan laboratorio fi


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