Pull-in-free design of electrically actuated carbon nanotube-based NEMS actuator assuming non-parallel electrodes arrangement

Abstract

In this numerical investigation, the nonlinear structural response of an electrostatic carbon nanotube (CNT) based nanoactuator assuming a non-parallel (out-of-plane) plates actuation configuration is examined. The actuating force is initiated by the asymmetry of the resultant electric fringing-fields caused mainly due to the non-parallel electrodes scheme. The nano-actuator is designed based on a carbon nanotube flexible moving electrode and two symmetrically located actuating stationary rectangular-shaped out-of-plane electrodes. First, the electrical problem of the nano-actuator is numerically solved to acquire the resultant actuating force. The force is then mathematically approximated from the outcomes of a 2D numerical solution of the electric problem via a finite-element-based numerical analysis. Then, the structural behavior of the CNT-based nano-actuator under the effect the resultant non-parallel electric fields is investigated numerically via a modal expansion process. The electro-mechanical model was constructed based on an Euler-Bernoulli continuous nonlinear beam model, where both the mid-plane stretching (geometric nonlinearity) and the electric non-parallel fringingfields effects have been taken into consideration. The reduced-order model (ROM) was derived using the Galerkin decomposition via modal decomposition process. The resultant nonlinear equations are solved numerically to get the static response of the considered CNT-based nano-actuator for various DC voltages. The eigenvalue problem is afterward derived and studied to get the variation of the fundamental as well as higher-order natural frequencies when the system is deflected by a non-zero DC amplitude. A detailed parametric study indicates an opportunity of having larger stroke as well as higher fundamental natural frequency for such CNT-based nano-actuator function of the assumed DC voltage amplitude, enabling it to be used as a tunable NEMS-based device without any pull-in scenario.

Nonlinear dynamics of a piezoelectrically laminated initially curved microbeam resonator exposed to out-of-plane electrostatic actuation

“…They indicated the significance of the horizontal and vertical distances between the stationary and moving electrodes as well as the thickness of the electrodes in the optimization of the actuator performance in such arrangements. In another study, Ouakad [26] numerically explored the nonlinear response of a CNT-based nanoactuator considering the out-of-plane actuation arrangement. Krylov et al [27] explored the efficient parametric excitation in microcantilever beams.…”