Michael Cullinan, Christopher DiBiasio, Larry Howell, Martin Culpepper, and Robert Panas
ABSTRACT: In this paper, we (1) present observations of the largedisplacement behavior of a clamped-clamped carbon nanotube (CNT) flexure element and (2) provide an overview of a new pseudo-rigid-body (PRB) model that predicts its elastomechanic behavior. We also show how this element may be combined with others to create a flexure bearing that can guide motions in nanoelectromechanical systems. The mechanical properties of CNTs make it possible for CNT-based devices to achieve high bandwidth (e.g. 10s of GHz) and large motion ranges that will enable exciting applications in nano-scale instrumentation and metrology. Unfortunately, this compliant element experiences strain stiffening that leads to localized bending deformations in the CNT. As such, linearized macro-scale elastomechanic models fail to accurately predict the static response of the beam. Molecular simulations were used to make observations on the device’s behavior and to extract its elastomechanic response. A PRB model for the new behavior was then created and its predictions were shown to match molecular simulation results with less than 13% deviation. This paper provides an understanding of (i) why this flexural element exhibits its unique behavior and (ii) how to model/make use of this behavior. The understanding and engineering models that are contained within this paper may be used to tailor the function of CNT-based flexures without the need to iterate with intensive molecular simulations. The work is in a nascent stage; however the results are an important pre-cursor to the realization of flexure-based nano-electro-mechanical systems.
KEYWORDS: Carbon Nanotube, Compliant Mechanism, Flexure Bearing
full paper (pdf)