Snap-Through Buckling of Micro/Nanobeams in Bistable Micro/Nanoelectromechanical Systems

Abstract

In this chapter, we investigate the instability behavior of an initially curved micro/nanobeam subject to an electrostatic force. The general governing equations of the curved beam are developed using Euler-Bernoulli beam theory and are solved using the Galerkin decomposition method. Firstly, the size effect on the symmetric snap-through buckling of the microbeam is studied. The size effect is accounted for in the beam model using the modified couple stress theory. The fringing field effect and the intermolecular effects, such as van der Waals and Casimir forces, are also included in the snap-through formulations. The model simulations reveal the significant effect of the beam size, and to a much lesser extent the effect of fringing field and intermolecular forces, upon the snap-through criterion for the curved microbeam. Secondly, the surface effects on the asymmetric bifurcation of the nanobeam are studied. The surface effects, including the surface elasticity and the residual surface tension, are accounted for in the model formulation. The results reveal the significant size effect due to the surface elasticity and the residual surface tension on the symmetry-breaking criterion for the considered nanobeam. IntroductionMicro/nano-electro-mechanical systems (MEMS/NEMS) have aroused great interest for their unique advantages such as small size, high precision, and low power consumption. One benchmark of MEMS/NEMS is the initially straight micro/ nanobeam system driven by electrostatic force, whose static and dynamic behaviors have been largely investigated in the literature (Carr et al.