Modeling of the elastic waves and vibrations of carbon nanotubes and nanocones
碳納米管和納米錐的振動及彈性波的模擬
Student thesis: Doctoral Thesis
Author(s)
Detail(s)
Awarding Institution | |
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Award date | 15 Jul 2010 |
Link(s)
Permanent Link | https://scholars.cityu.edu.hk/en/theses/theses(b50a6180-9fc5-478c-91fb-f2c979d7a864).html |
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Other link(s) | Links |
Abstract
The extraordinary mechanical and physical properties of carbon nanotubes (CNTs) have been studied
using a range of theories and methods. The mechanical properties of CNTs can be classified into
statistic mechanics and dynamics properties. This study focuses on the dynamic mechanical
properties of CNTs and single-walled carbon nanocones (SWCNCs). The dynamic mechanical behavior
of CNTs and SWCNCs, including vibration and elastic waves, are studied by using molecular
dynamics (MD) simulation and continuum mechanics models. The elastic wave propagation in CNTs is
investigated with nonlocal and classical (local) continuum mechanics models and verified by MD
simulation. The free vibrations of CNTs and SWCNCs with different boundary conditions are studied
using continuum mechanics models and MD simulation. The applicability of the nonlocal and
classical continuum models of CNTs is investigated through the problems of elastic waves and
vibration.
MD simulations of flexural wave, transverse wave, and torsional wave propagation in CNTs are
generated. The second-generation reactive empirical bond order (REBO) potential is used in the MD
to simulate the short-range interaction force between atoms. The propagation of elastic waves in
CNTs is investigated by using nonlocal beam models and nonlocal shell models. The
applicability of nonlocal continuum models for elastic waves in CNTs is verified by MD
simulation. The scale parameter in nonlocal theory is estimated by matching the dispersion
relation obtained from the continuum models with the MD results. It is found that the value of is
mainly dependent on the different kinds of elastic waves investigated, rather than the structure
of the CNT, such as the diameter, the chirality and the single walled or double walled CNTs. The
nonlocal beam and shell models are found to offer a better prediction of the dispersion
relationships than the classical models when the wavenumber is very large. The non-coaxial
vibration of double-walled carbon nanotubes (DWCNTs) at high frequencies is also investigated
with MD simulation. The van der Waals (vdW) interaction between the adjacent tubes is found to
have little effect on the noncoaxial flexural vibration of CNTs. The nonlocal elastic Timoshenko
beam theory is found to be inapplicable for modeling the noncoaxial wave propagation in CNTs.
0e0e
The free transverse, longitudinal, and torsional vibrations of single-walled carbon nanotubes
(SWCNTs) are investigated using a nonlocal beam model and a nonlocal rod model, and verified by
MD simulation. The nonlocal Timoshenko beam model offers a better prediction of the fundamental
frequencies of shorter SWCNTs than the local beam models. The nonlocal rod model is employed to
study the longitudinal and torsional vibrations of SWCNTs, and is shown to give good predictions
of the MD results for shorter SWCNTs. The nonlocal and classical continuum models are in good
agreement with the MD simulation results for relatively longer SWCNTs.
Finally, the free transverse and longitudinal vibrations of SWCNCs with different boundary
conditions and apex angles are studied by MD simulation, and the fundamental frequencies are
obtained. The fundamental frequencies of SWCNCs are also compared with those of SWCNTs with radii
equal to top radii of SWCNC.
- Nanotubes, Mechanical properties, Carbon