Molecular dynamics simulation for investigating intrinsic mechanical properties of carbon nanotubes and graphene monolayers.

摘要

Carbon nanostructures have exhibited fascinating mechanical and electrical properties such as high in-plane elastic modulus and thermal conductivity, which implies promising potential applications in electromechanical devices. Using molecular dynamics simulation technique, this thesis explores intrinsic mechanical properties of two representative carbon nanostructures; single-walled carbon nanotube and graphene monolayer. Nanoresonators based on single-walled carbon nanotubes have a potential application in nanoelectromechanical systems (NEMS), and this research first investigates the oscillating behaviors of carbon nanotubes (CNT) at different system temperatures and reveals size-dependent resonating behaviors of CNT. The energy dissipation rates are derived and the quality factors at various temperatures are analyzed. Graphene is a one-atom-thick two dimensional crystal structure such that it is basic building block of CNT, fullerene, and graphite. Graphene membrane itself presents mechanical properties which could be used as a gas or liquid nano sensors in the form of nano balloon and nano drums. This study thus reports graphene resonance properties by using classical molecular dynamics to simulate its feasibility as a nanoresonator. The resonance frequencies and their dependence on nanoribbon size are studied. Finally, the mechanical response of graphene to gas pressure is presented through the molecular dynamics simulation of cylindrical bulge tests. Graphene's behavior under extreme pressure is studied and the result is analyzed for their use of gas sensor and hydrogen storage.