Design and modeling of carbon nanotube-based compliant mechanisms

Abstract

The objective of this research is to generate the knowledge required to adapt macro- and microscale compliant mechanism theory to design carbon nanotube-based nano-scale compliant mechanisms. Molecular simulations of a nano-scale parallel guiding mechanism uncovered three regions of behavior. Region I is governed by the bulk deformation of the carbon nanotubes. Region II is characterized by hinge-like flexing of four "kinks" that occur due to buckling of the carbon nanotube walls. Region III, an intermediate region, exhibits direction dependant behavior. We report on the ability of a conventional compliant mechanism modeling approach, the pseudo-rigid-body model, to predict the region I behavior of a nano-scale parallel guiding mechanism that uses single-walled (5,5) carbon nanotubes as the flexural elements. Van der Waals forces were found to affect the kinematic and elastomechanic behavior of the nano-scale parallel guiding mechanism. A modified value of the pseudo-rigid-body model stiffness coefficient is presented to capture the affect of van der Waals interactions within (5,5) nanotubes during region I operation.

(cont.) Molecular simulation of region I behaviors match the modified pseudo-rigid-body model predictions of (1) kinematic behavior with less than 7.3 % error and (2) elastomechanic behavior with less than 8 % error. Although region I is of the most interest because of its well-defined and stable nature, region II motion is also investigated to provide a basis for establishing future work in this region.