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Multiscale Simulation of Carbon Nanotubes Using Coupled Atomistic- Continuum Modeling

Motezaker, Mohsen | 2016

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 49091 (53)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Khoei, Amir Reza; Jahanshahi, Mohsen
  7. Abstract:
  8. Carbon nanotubes are cylinders in Nano scale formed of carbon atoms with covalent bonds that contain a significant electrical and mechanical features. Carbon nanotubes are divided into two main types: multi-walled carbon nanotubes (MWCNTs) and single walled carbon nanotubes (SWCNTs). A SWCNT is a rolled graphene sheet (graphene is in fact a single sheet of graphite). SWCNTs has lately been considered as one of most interesting research cases. The reason why researchers have been fond of investigating about graphene has been its unconventional quantum hall effects, high room-temperature electrical conductivity and its mechanical stability despite of being composed of single layer atom structure. This research aims to apply an efficient approach for multi-scale simulations of SWCNT and the unrolled version, Graphene sheet. Multiscale method has been used in order to have the advantages of continuum mechanic approach such as its recognition and is not computationally expensive, along with the accuracy of atomistic simulation. The Cauchy-Born rule is used to link the deformation of atom lattice vectors at the atomic level with the material deformation in a macro continuum level. Therefore, the single layer graphene has been chosen as the representative area element (RAE) of SWCNTs, Empirical interatomic potentials are applied so that stress fields and modulus fields can be computed by the derivations of potential forms from displacement fields and rotation fields. A finite element approach is implemented. Results of simulations for single-walled carbon nanotubes under stretching and compression are presented and compared with full atomic simulations. In addition, critical buckling strains for single-walled carbon nanotubes are predicted in this research
  9. Keywords:
  10. Carbon Nanotubes ; Graphene Sheet ; Molecular Mechanics ; Molecular Dynamics ; Finite Element Method ; Multi-Scale Analysis ; Cauchy-Born Rule

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