Papers by Keyword: Pull-In Voltage

Abstract: The dynamics of the micro-cantilever with linearly varying width under electrostatic actuation is presented. The restraining displacement and voltage dissociating the unstable and stable operating region are determined by Bubnov-Galerkin approach. The influence of the variation in geometry of micro-beam and change in material parameters on the pull-in conditions is investigated. The increase of 24.27% is obtained in pull-in displacement when the tip width is reduced to 0.

Abstract: Fatigue of MEMS structures may occur after cyclic vibration loading, which can lead to the material degradation. A test bench was built for mechanical fatigue testing, especially for the structures that actuated by electrostatic force. A RF MEMS switch which was made of gold was tested; the material mechanical characteristic was monitored during the tests by means of the value of pull-in voltage, which is related to the change of the Youngs modulus. The fatigue stress was produced by an alternating voltage, and the amplitude of which is from 15V to 65V. The excitation frequency and the actuation time were used as a counter for the number of cycles. The results show that there is no detectable mechanical fatigue after actuation up to one billion cycles.

Abstract: The nonlinear dynamic behavior of the micro actuators is analyzed in this paper. In general, analysis of the electrostatic device is quite difficult and complicated due to the electrostatic coupling effect and the nonlinear electrostatic force. In this study, a hybrid method for the micro-structure system, which combines the differential transformation and finite difference approximation techniques, is used to overcome the nonlinear electrostatic coupling phenomenon. The analysis takes account of the electrostatic coupling effect, the fringing field effect, the residual stress, the nonlinear electrostatic force and squeeze-film damping effect. Finally, the actuating conditions which ensure the stability of the micro actuators are identified by reference to phase portraits.

Abstract: For MEMS devices actuated by electrostatic force, unexpected failure modes can be hardly predicted when the electrostatic force coupled with the shock. A response model is established when a micro cantilever subjected to electrostatic force and mechanical shock. First, based on the theory of transverse forced vibration in vibration mechanics, the equation of motion under shock and electrostatic fore is presented. Then the reduced order model is gained after simplifying by mode superposition method. The computing results indicate that: the shock amplitude and duration are the key factors to affect the reliability of the device; the shock load and electrostatic forces make the threshold voltage much lower than the anticipated value. The micro cantilever may collapse to the substrate even at a voltage far lower than the pull-in voltage. This early dynamic pull-in instability may cause some failures such as short circuit, adhesion or collision damage.

Abstract: This Paper presents the design and simulation of single walled carbon nanotube (SWCNT) based cantilever type electrostatic actuator using finite element analysis method (FEM). The pull-in voltage has been calculated for various chirality of the nanotube based cantilever beam actuators. The pull-in voltage are obtained for the various gap between electrode and ground of the cantilever beam through extensive simulations using ANSYS software. The results obtained shows that pull-in voltages varies from 2.5 to 13.5V with respect to nanotube chirality and gap length.

Abstract: Using traditional methods such as perturbation theory or Galerkin approach method to analyze the dynamic response of electrostatic devices is not easy due to the complexity of the interactions between the electrostatic coupling effect, the fringing field effect, the residual stress, the nonlinear electrostatic force and squeeze-film damping effect. Accordingly, the present study proposes a new approach for analyzing the dynamic response of such devices using a hybrid numerical scheme comprising the differential transformation method and the finite difference method by pure DC or combined DC / AC loading. The validity of the proposed scheme is confirmed by comparing the results obtained for the pull-in voltage of the micro-beam with those presented in the literature derived using a variety of schemes. Overall, the results show that the hybrid numerical scheme provides a suitable means of analyzing the nonlinear dynamic behavior of a wide variety of common electrostatically-actuated microstructures.

Abstract: The effects of temperature change on the pull-in behavior and on the capacitance of the RF MEMS clamped-clamped capacitive switch are quite heavy because of the larger slenderness ratio of the MEMS clamped-clamped switch beam. A one-dimensional three-stage static model with temperature change for analyzing the beam was presented based on the small displacement assumptions, in which the clamped-clamped beam was subjected to both the electrostatic forces and the temperature change. First, the model was used to calculate the capacitance of the RF MEMS clamped-clamped capacitive switch in different states. Then , the effects of temperature change on the capacitance of the clamped-clamped capacitive switch for some different geometry dimensions were analyzed. From the analysis the effect of some geometry dimensions, such as the length of the beam, the depth of the beam and so on, at different temperature changes on the capacitance can be understood and some conclusions may be useful to the design of the MEMS clamped-clamped capacitive switch with the temperature change.

Abstract: The Ansys simulate software is utilized to analyze pull-in voltages and stresses of the fixed end of micro- cantilever beam with different thicknesses respectively. Based on the analysis of the electrostatic force at the pull-in voltage, the stress of fixed end of micro-beam and the maximum deflection are obtained. The relationship between the stress of fixed end and thickness is established. The results show that the mutation thickness of the stress and the pull-in voltage are at and respectively , it is consistent with the intrinsic size of the polycrystalline copper micro-beam.

Abstract: This paper modified the linear distributed load (LDL) model for cantilever nano-beams . A linear load model which suits boundary conditions was proposed to approximate with nonlinear intermolecular and electrostatic interactions. In the modified LDL model, under considerating the effect of the small scale, the pull-in instability behaviour of nano-actuators subjected to an electrostatic force and intermolecular force had been investigated. The results showed that the modified LDL model is more consistent with the actual situation than LDL model.

Abstract: In this paper, the static pull-in instability of torsional nanoelectromechanical systems (NEMS) with coupling effect between torsion and bending is investigated considering the effect of translation elastic boundary condition. A set of normalized equations governing the static actuation properties of the torsional actuator is derived to demonstrate the relationships between the parameters of static characteristics, such as torsion angle, vertical displacement, and applied voltage. The results from this model demonstrated that the real model of boundary condition (elastic boundary condition) is very important issue which must be considered in manufacturing process.