Computational investigation of the mechanical properties of nanomaterials

The mechanical responses of carbon nanotubes are examined using classical molecular dynamics simulations. Several different types of nanotubes are considered, including pristine single-walled tubes that are empty, filled with fullerenes to form peapods, filled with other nanotubes to form multi-walled tubes, or chemically functionalized. In addition, the responses of single-walled nanotubes with wall vacancies are considered. The results show how the bending force of filled nanotubes increases relative to the bending force of empty nanotubes and indicates how these increases come about. In addition, the simulations reveal the way in which the magnitude of these increases depend on the type of filling material and, in the case of multi-walled tubes, the number of inner tubes. These simulations further illustrate the way in which the inner nanotubes support higher external loads than the fullerenes in cases when the outer nanotubes are identical. The results also indicate that both the bending and buckling forces depend on temperature and the reasons for this dependence are discussed. Lastly, the simulations demonstrate the way in which the introduction of vacancy defects and covalently bound functional groups to the nanotube walls degrades the nanotubes' mechanical properties.