scholarly journals Effect of Squeeze Film Damping and AC Actuation Voltage on Pull-in Phenomenon of Electrostatically Actuated Microswitch

2016 ◽  
Vol 144 ◽  
pp. 891-899 ◽  
Author(s):  
C. Sri Harsha ◽  
C.S.R. Prasanth ◽  
Barun Pratiher
Keyword(s):  
Actuation Voltage ◽  
Squeeze Film ◽  
Electrostatically Actuated ◽  
Squeeze Film Damping ◽  
Ac Actuation

Nonlinear Vibration of Electrostatically Actuated MEMS Resonators Under Parametric and External Excitations

2007 ◽  
Author(s):  
Wen-Ming Zhang ◽  
Guang Meng ◽  
Di Chen
Keyword(s):  
Dynamic Characteristics ◽  
Nonlinear Dynamic ◽  
Squeeze Film ◽  
Electrostatically Actuated ◽  
Squeeze Film Damping ◽  
Mems Resonators ◽  
Nonlinear Dynamic Characteristics ◽  
Dynamical Parameters ◽  
Parametric And External Excitations ◽  
Significant Attention

Electrostatically actuated resonant MEMS (Micro-electromechanical Systems) have gotten significant attention due to their geometric simplicity and broad applicability. In this paper, analyses and simulations for the dynamics of electrostatically actuated MEM structures under parametric and external excitations are presented. The presented model and methodology enable simulation of the dynamics of the electrostatic MEM structure undergoing small motions. The numerical results showing the effects of varying the applied voltages and the squeeze film damping on the resonant frequencies and nonlinear dynamic characteristics are given in detail. Resonant frequency and peak amplitude are examined for variation of the dynamical parameters involved. It is demonstrated that the system goes through a complex nonlinear oscillation as the system parameters change. This investigation provides an understanding of the nonlinear dynamic characteristics of electrostatically actuated resonant MEMS.

scholarly journals Dynamics of Nonlinear Coupled Electrostatic Micromechanical Resonators under Two-Frequency Parametric and External Excitations

2010 ◽  
Vol 17 (6) ◽  
pp. 759-770 ◽  
Author(s):  
Wen-Ming Zhang ◽  
Guang Meng ◽  
Ke-Xiang Wei
Keyword(s):  
Dynamic System ◽  
Quality Factor ◽  
Electrostatic Force ◽  
Squeeze Film ◽  
Largest Lyapunov Exponent ◽  
Nonlinear Phenomena ◽  
Electrostatically Actuated ◽  
Squeeze Film Damping ◽  
Mems Resonators ◽  
Parametric And External Excitations

In this paper, nonlinear dynamics and chaos of electrostatically actuated MEMS resonators under two-frequency parametric and external excitations are investigated analytically and numerically. A nonlinear mass-spring-damping model is used to accounting for squeeze film damping and the parallel plate electrostatic force. The micro-structure is excited by a dc bias electrostatic force and a harmonic force with a frequency tuned closely to their fundamental natural frequencies (combination oscillation). The quality factor is calculated for the microcantilever beam of the resonator considering squeeze film damping. The effect of nonlinear squeeze film damping on the frequency response, quality factor, resonant frequency and nonlinear dynamic characteristics of the dynamic system are provided with numerical simulations using the bifurcation diagram, Poicare maps, largest Lyapunov exponent and phase portrait. The results show that the dynamic system goes through a complex nonlinear vibration as the system parameters change. It is indicated that the effect of nonlinear squeeze film damping should be considered due to its decreasing the quality factor and changing the nonlinear phenomena of the MEMS resonators.

DYNAMIC PULL-IN INSTABILITY AND VIBRATION ANALYSIS OF A NONLINEAR MICROCANTILEVER GYROSCOPE UNDER STEP VOLTAGE CONSIDERING SQUEEZE FILM DAMPING

2013 ◽  
Vol 05 (03) ◽  
pp. 1350032 ◽  
Author(s):  
M. MOJAHEDI ◽  
M. T. AHMADIAN ◽  
K. FIROOZBAKHSH
Keyword(s):  
Differential Equations ◽  
Natural Frequencies ◽  
Proof Mass ◽  
Dynamic Instability ◽  
Squeeze Film ◽  
Electrostatically Actuated ◽  
Damping Coefficients ◽  
Step Voltage ◽  
Runge Kutta Method ◽  
Squeeze Film Damping

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 considering nonlinearities in curvature, inertia, damping and electrostatic forces. Afterward, the Gelerkin decomposition method is implemented to reduce partial differential equations of microgyroscope deflection to a system of nonlinear ordinary equations. By using the 4th order Runge–Kutta method, the nonlinear ordinary equations are solved for various values of damping coefficients, air pressures, base rotation and various initial gaps between the proof mass electrodes and the substrates. Results show that the geometric nonlinearity increases the dynamic pull-in voltage and also consideration of the base rotation gives an improved evaluation of the dynamic instability. It is shown that the squeeze film damping has a considerable influence on the dynamic deflection of the microgyroscopes.

Fringing Electrostatic Field Actuation of Microplates for Open Air Environment Sensing

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
Avinoam Rabinovich ◽  
Assaf Ya'akobovitz ◽  
Slava Krylov
Keyword(s):  
Electrostatic Force ◽  
Fringe Field ◽  
Squeeze Film ◽  
Expansion Theorem ◽  
Electrostatically Actuated ◽  
Squeeze Film Damping ◽  
Element Simulation ◽  
Fringing Field ◽  
Field Lines ◽  
Operational Failure

In the present study, we tested the feasibility of actuation of microplates by fringing electrostatic fields, i.e., field lines between plates and the sidewalls supporting them. Unlike the common close-gap actuation mechanism usually used in these kinds of devices, we present an alternative operational principle based on an electrostatic fringe field for the actuation of micro electromechanical (MEMS) plates, which is especially beneficial for open air environment operation. In order to validate the actuation principle, a circular MEMS plate was considered and an analytical model was built. The electrostatic force applied to the plate was extracted from a solution of a steady boundary value problem of a cylinder and was validated numerically using finite element simulation. This was followed by a solution of the plate governing equation of motion using an expansion theorem. Devices of two different geometries were fabricated and operated. Actuation of the plates by means of the fringing field was demonstrated experimentally. The proposed architecture and actuation principle is advantageous and overcomes many of the difficulties encountered in microplates electrostatically actuated by a close-gap electrode. Due to the absence of a small gap, the device is not prone to pull-in instability and stiction and is not subjected to squeeze-film damping. Moreover, since the actuation is separated from the front side of the device, open air contaminations, such as humidity or dust, cannot cause operational failure. In addition, the device is especially beneficial for mass sensing in an open environment, as well as flow senors where a flush-mounted smooth surface is important.

Modeling Squeeze-Film Damping of Electrostatically Actuated Microplates Undergoing Large Deflections

2005 ◽  
Author(s):  
Mohammad I. Younis ◽  
Ali H. Nayfeh
Keyword(s):  
Mode Shapes ◽  
Squeeze Film ◽  
Beam Equation ◽  
Large Deflections ◽  
Static Deflection ◽  
Quality Factors ◽  
Electrostatically Actuated ◽  
Squeeze Film Damping ◽  
Plate Equations ◽  
Analytical Expressions

A model for the dynamics of electrostatically actuated microplates undergoing large deflections under the effect of squeeze-film damping is presented. The model predicts the quality factors of microplates under a wide range of gas pressures and applied electrostatic forces up to the pull-in instability. The model utilizes the nonlinear Euler-Bernoulli beam equation, the von Ka´rma´n plate equations, and the compressible Reynolds equation. The static deflection of the microplate is calculated using the beam model. Analytical expressions are derived for the pressure distribution in terms of the plate mode shapes around the deflected position using perturbation techniques. The static deflection and the analytical expressions are substituted into the plate equations, which are solved using a finite-element method. Several results are presented showing the effect of the pressure and the electrostatic force on the structural mode shapes, the pressure distributions, the natural frequencies, and the quality factors.

scholarly journals Optimization Strategy for Resonant Mass Sensor Design in the Presence of Squeeze Film Damping

2009 ◽  
Author(s):  
Chengzhang Li ◽  
Michele H. Miller
Keyword(s):  
Analytical Approach ◽  
Nonlinear Effects ◽  
Squeeze Film ◽  
Sensor Design ◽  
Optimization Strategy ◽  
Mass Sensor ◽  
Dynamics Modeling ◽  
Electrostatically Actuated ◽  
Squeeze Film Damping ◽  
Air Damping

This paper investigates the design optimization of an electrostatically actuated microcantilever resonator that operates in air. The nonlinear effects of electrostatic actuation and air damping make the structural dynamics modeling more complex. There is a need for an efficient way to simulate the system behavior so that the design can be more readily optimized. This paper describes an efficient analytical approach for determining the optimum design for a microcantilever resonant mass sensor. One simple case is described. The sensor design is a square plate that is coated with a functional polymer and attached to the substrate with folded leg springs. The plate has a square hole in the middle to reduce the effect of squeeze film damping. With the analytical approach, the optimum hole size for maximum sensitivity is found.

Coupled effects of surface interaction and damping on electromechanical stability of functionally graded nanotubes reinforced torsional micromirror actuator

2021 ◽  
pp. 030932472110368
Author(s):  
Weidong Yang ◽  
Menglong Liu ◽  
Linwei Ying ◽  
Xi Wang
Keyword(s):  
Casimir Force ◽  
Volume Fraction ◽  
Nonlocal Parameter ◽  
Saddle Points ◽  
Functionally Graded ◽  
Heteroclinic Orbits ◽  
Phase Portraits ◽  
Squeeze Film ◽  
Squeeze Film Damping ◽  
Tilting Angle

This paper demonstrated the coupled surface effects of thermal Casimir force and squeeze film damping (SFD) on size-dependent electromechanical stability and bifurcation of torsion micromirror actuator. The governing equations of micromirror system are derived, and the pull-in voltage and critical tilting angle are obtained. Also, the twisting deformation of torsion nanobeam can be tuned by functionally graded carbon nanotubes reinforced composites (FG-CNTRC). A finite element analysis (FEA) model is established on the COMSOL Multiphysics platform, and the simulation of the effect of thermal Casimir force on pull-in instability is utilized to verify the present analytical model. The results indicate that the numerical results well agree with the theoretical results in this work and experimental data in the literature. Further, the influences of volume fraction and geometrical distribution of CNTs, thermal Casimir force, nonlocal parameter, and squeeze film damping on electrically actuated instability and free-standing behavior are detailedly discussed. Besides, the evolution of equilibrium states of micromirror system is investigated, and bifurcation diagrams and phase portraits including the periodic, homoclinic, and heteroclinic orbits are described as well. The results demonstrated that the amplitude of the tilting angle for FGX-CNTRC type micromirror attenuates slower than for FGO-CNTRC type, and the increment of CNTs volume ratio slows down the attenuation due to the stiffening effect. When considering squeeze film damping, the stable center point evolves into one focus point with homoclinic orbits, and the dynamic system maintains two unstable saddle points with the heteroclinic orbits due to the effect of thermal Casimir force.

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