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Stability Analysis of Hybrid Nanotubes Based on the Nonlocal Continuum Theories

Rafati Heravi, Jacob | 2010

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41914 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Asghari, Mohsen
  7. Abstract:
  8. Strong van der Waals (vdW) potential fields of carbon nanotubes (CNTs) makes them capable to encapsulate some nanostructures inside their hollow space, which leads to the construction of new hybrid nanostructures under specific conditions. Carbon nano-peapods, carbon nanowires and the hybrid of DNA and CNT are the main categories of hybrid nanostructures of CNT. Characteristics of hybrid nanotubes are unique and different from those of CNT. In nanostructures, the lattice spacing between individual atoms is considerable with respect to the structural dimensions. Also, the range of internal characteristic length is relatively close to external ones. So that utilizing the classical continuum with the assumption of the structural continuity is somehow doubtful. In other words, it is better that the classical continuum theory which neglect small scale effects and natural discontinuity of atomic range structures be replaced with appropriate non-classical ones which consider the small scale effects. The nonlocal continuum theory is one of the non-classic continuum theories in which the small scale effects are considered when writing the constitutive equations. In this thesis, the vdW interactions between the encapsulated nanostructure and CNT are modeled by pressure and force distributions. Then the equations governing the stability of the continuum-based models string, rod and shell are obtained using the nonlocal continuum theory. The buckling instability of the hybrid nano-structures under various mechanical loadings (radial pressure, axial compressive force and torsional moment) are investigated using the nonlocal continuum models. Finally, by providing some numerical examples, the obtained critical loads of special hybrid nanotubes based on the nonlocal models are compared with those of the available molecular dynamics results. For the hybrid nanotubes which are generated spontaneously, both nonlocal continuum theory and molecular dynamics predict that, presence of the encapsulated material causes increasing of resistance against buckling instability of the CNT under various loadings
  9. Keywords:
  10. DNA ; Carbon Nanotubes ; Nonlocal Elasticity Theory ; Buckling Instability ; Hybrid Nanostructures ; Carbon Nanopeapod ; Small Scales Effect

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