Static and Dynamic Analysis of Carbon Nanotube-Based Switches

In this paper, we report on molecular dynamics (MD), continuum (based on linear and nonlinear beam theories) and combined molecular dynamics/continuum simulation of carbon nanotube based nanoelectromechanical switches. As a prototype device, we study the pull-in voltage characteristics of a nanoelectromechanical switch made of a suspended single wall nanotube over a ground plane. The various simulations (MD, continuum and combined MD/continuum) have been performed accounting for the electrostatic and van der Waals forces between the nanotube and the ground plane. The results from the nonlinear continuum theory compared well with the results from MD, except, for cases, where nanotube buckling was observed. When buckling occurs, the electromechanical behavior of the switch is simulated by employing a combined MD/continuum approach. The combined MD/continuum approach is computationally more efficient compared to the MD simulation of the entire device. Static and dynamic pull-in, pull-in time and fundamental frequency analysis is presented for fixed-fixed and cantilever carbon nanotube switches.

On the Symmetry and Stability of Thermoelastic Solids

For the most part, nonlinear continuum theory has been based on the premise that the symmetry of a material never really changes. To analyze common phase transitions, we need to revise such theory of symmetry, but this is easier said than done. What seems to be needed is a theory of symmetry which is, in some sense, more local. Classical linear theories have a local nature, dealing only with the neighborhood of some state, so it seems worthwhile to rethink what is involved in symmetry considerations for them. Here, and not only here, symmetry is strongly linked to stability. Our purpose is to elaborate these matters.