Dynamic pull-in instability of electrostatically actuated beams incorporating Casimir and van der Waals forces

Abstract In this study, influences of intermolecular forces on the dynamic pull-in instability of electrostatically actuated beams are investigated. The effects of midplane stretching, electrostatic actuation, fringing fields, and intermolecular forces are considered. The boundary conditions of the beams are clamped—free and clamped—clamped. A finite-element model is developed to discretize the governing equations, and Newmark time discretization is then employed to solve the discretized equations. The static pull-in instability is investigated to validate the model. Finally, dynamic pull-in instability of cantilevers and double-clamped beams are studied considering the Casimir and van der Waals effects. The results indicate that by increasing the Casimir and van der Waals effects, the effect of inertia on pull-in values considerably increases.