Sharif Digital Repository

In this study, homotopy analysis method is used to derive analytic solutions to predict dynamic pull-in instability of electrostatically-actuated microsystems. The model considers midplane stretching, initial stress, distributed electrostatic force and fringing fields effect. Influences of different parameters on dynamic pull-in instability are investigated. Results are in good agreement with numerical and experimental findings. © 2009 Elsevier Ltd. All rights reserved  

Based on the nonlocal Euler–Bernoulli beam theory, a theoretical approach is developed to investigate the effects of small scale and intermolecular force on the dynamic pull-in behavior of electrostatically actuated nanoresonators. To this purpose, nanoresonators are modeled as multilayer beams with rectangular cross-sections and fixed-fixed and fixed-free end conditions which are embedded in an elastic medium containing Winkler and Pasternak elastic foundations. Also, the effects of nonlocal parameter, fringing field due to the finite width of beams, Casimir or van der Waals intermolecular forces, nonlinear term induced by mid-plane stretching and Winkler and Pasternak elastic foundations... 

In this paper, a nonlinear model is used to analyze the dynamic pull-in instability and vibrational behavior of a microcantilever gyroscope. The gyroscope has a proof mass at its end and is subjected to nonlinear squeeze film damping, step DC voltages as well as base rotation excitation. The electrostatically actuated and detected microgyroscopes are subjected to coupled flexural-flexural vibrations that are related by base rotation. In order to detune the stiffness and natural frequencies of the system, DC voltages are applied to the proof mass electrodes in drive and sense directions. Nonlinear integro differential equations of the system are derived using extended Hamilton principle... 

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... 

This paper investigates the dynamic pull-in behavior of microplates actuated by a suddenly applied electrostatic force. Electrostatic, elastic and fluid domains are involved in modeling. First-order shear deformation plate theory and classical plate theory are used to model the geometrically nonlinear microplates. The equations of motion are descritized by the finite element method. The effects of nonlinearity, fluid pressure, initial stress and different geometric parameters on dynamic behavior are examined. In addition, the influences of initial stress and actuation voltage on oscillatory behavior of microplates are evaluated. © 2009 Elsevier Masson SAS. All rights reserved