A Comparative Study of Thin-Film and Reynolds Equation Simulation Models for Squeeze Film Damping in MEMS Plate Structures

2011 ◽  
Vol 403-408 ◽  
pp. 4580-4587
Author(s):  
Wei Guo Liu ◽  
Wei Wang ◽  
Shou Jun Peng
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Knudsen Number ◽  
Parallel Plate ◽  
Reynolds Equation ◽  
Perforated Plate ◽  
Squeeze Film ◽  
Squeeze Film Damping ◽  
Knudsen Numbers ◽  
Viscosity Modification

Squeeze film damping effect of MEMS parallel plate structure was analyzed based on thin film and Reynolds Equation in ANSYS under the different Knudsen numbers. Perforation effect of parallel plate with certain size and operating frequency was achieved under the different Knudsen numbers, the simulation results of two methods are very close. For unperforated plate, when Knudsen number is below 0.01, the discrepancy of two simulations is nonsignificant, and it grows up with Knudsen number. But gas rarefaction effects related with Knudsen number was considered in heat transfer analogy theory and used viscosity modification according to Veijola model, two simulations get the same result. For perforated plate, the simulation discrepancy of two methods will be great because of channel flow's effect and also grow up with Knudsen number, it can't be avoided even if the channel flow's effect and viscosity modification were concerned in heat transfer analogy theory.

Experimental Verification of Rarefied Gas Squeezed-Film Damping Models Used in MEMS

2006 ◽  
Author(s):  
Lukas Mol ◽  
Luis A. Rocha ◽  
Edmond Cretu ◽  
Reinoud F. Wolffenbuttel
Keyword(s):  
Experimental Verification ◽  
Parallel Plate ◽  
Rarefied Gas ◽  
Experimental Results ◽  
Squeeze Film ◽  
Border Effects ◽  
Knudsen Numbers ◽  
Electrostatic Mems ◽  
Simulation Errors

Existing compact parallel-plate squeeze-film models including rarefaction and border effects are verified using the experimental results of a new electrostatic MEMS actuation technique that enables full gap positioning. Measurements at high Knudsen numbers ranging from 0.03 to 0.18 are performed and results compared to the models. The simulation errors are confirmed to be lower than 20%. The experiments also indicate that both gas rarefaction and border effects have to be included in any model.

The Effect of Shape and Distribution of Perforations on Squeeze-Film Damping in Parallel Plate Capacitors

2009 ◽  
Author(s):  
Weili Cui ◽  
Ronald N. Miles ◽  
Dorel Homentcovsci
Keyword(s):  
Parallel Plate ◽  
Internal Heat ◽  
Optical Switches ◽  
Squeeze Film ◽  
Mems Devices ◽  
Capacitive Sensing ◽  
Squeeze Film Damping ◽  
Squeeze Film Effect ◽  
Capacitive Mems ◽  
Stationary Plate

The effect of the shape and distribution of perforations in parallel plate capacitive MEMS devices on squeeze-film damping is presented. The squeeze film effect is the most important damping effect on the dynamic behavior of most MEMS devices that employ capacitive sensing and actuation, which typically employ narrow air gaps between planar moving surfaces [1, 2]. The stationary plate of a capacitive device is often perforated to reduce the damping and sensor noise and improve the frequency response. The formula for determining the total viscous damping in the gap contains a coefficient Cp that is associated with the geometry and distribution of the holes on the stationary plate. In this study, the coefficient Cp is determined using the finite element method using ANSYS by analogy with heat conduction in a solid with internal heat generation. Round, elliptical, rectangular, and oval holes that are distributed either aligned or offset are analyzed and compared. It is shown that the surface fraction occupied by the perforations is not the only factor that determines Cp. Both the shape and distribution strongly affect the damping coefficient [3, 4]. By using elongated perforations that are properly distributed, the squeeze film damping could be minimized with the minimum amount of perforation. The analysis performed in this work is quite general being applicable to a very large spectrum of frequencies and to various fluids in capacitive sensors. These results can facilitate the design of mechanical structures that utilize capacitive sensing and actuation, such as accelerometers, optical switches, micro-torsion mirrors, resonators, microphones, etc.

The Effect of Squeeze-Film Damping on Suppressing the Shock Response of MEMS

2009 ◽  
Author(s):  
Hadi Yagubizade ◽  
Mohammad I. Younis ◽  
Ghader Rezazadeh
Keyword(s):  
Reynolds Equation ◽  
Element Model ◽  
Squeeze Film ◽  
Beam Equation ◽  
Mechanical Shock ◽  
Shock Loads ◽  
Reduced Order ◽  
Squeeze Film Damping ◽  
Nonlinear Finite Element Model ◽  
Euler Bernoulli Beam

This paper presents an investigation into the response of a clamped-clamped microbeam to mechanical shock under the effect of squeeze-film damping (SQFD). In this work, we solve simultaneously the nonlinear Reynolds equation, to model squeeze-film damping, coupled with a nonlinear Euler-Bernoulli beam equation. A Galerkin-based reduced-order model and a finite-deference method (FDM) are utilized for the solid domain and for the fluid domain, respectively. Several results showing the effect of gas pressure on the response of the microbeams are shown. Comparison with the results of a multi-physics nonlinear finite-element model is presented. The results indicate that squeeze-film damping has more significant effect on the response of microstructures in the dynamic shock loads compared to the quasi-static shock loads.

Dynamics of Multilayer Microplates Considering Nonlinear Squeeze Film Damping

2006 ◽  
Author(s):  
M. T. Ahmadian ◽  
M. Moghimi Zand ◽  
H. Borhan
Keyword(s):  
Finite Element ◽  
Finite Difference ◽  
Reynolds Equation ◽  
Finite Difference Methods ◽  
Shear Deformation Theory ◽  
Single Layer ◽  
Squeeze Film ◽  
First Order ◽  
Squeeze Film Damping ◽  
Good Agreement

This paper presents a model to analyze pull-in phenomenon and dynamics of multi layer microplates using coupled finite element and finite difference methods. First-order shear deformation theory is used to model dynamical system using finite element method, while Finite difference method is applied to solve the nonlinear Reynolds equation of squeeze film damping. Using this model, Pull-in analysis of single layer and multi layer microplates are studied. The results of pull-in analysis are in good agreement with literature. Validating our model by pull-in results, an algorithm is presented to study dynamics of microplates. These simulations have many applications in designing multi layer microplates.

Air Damping Effects of MEMS Parallel-Plate Structure Using ANSYS Thin Film Analysis

2011 ◽  
Vol 403-408 ◽  
pp. 4588-4592
Author(s):  
Xiong Xing Zhang ◽  
Shou Jun Peng ◽  
Jin Long Zou
Keyword(s):  
Thin Film ◽  
Pressure Distribution ◽  
Operating Frequency ◽  
Squeeze Film ◽  
Film Analysis ◽  
Thin Film Analysis ◽  
Squeeze Film Damping ◽  
Air Damping ◽  
Damping Effects ◽  
Accommodation Factor

ANSYS thin film analysis was adopted to simulate the effects of squeeze film damping. The relation of damping effects versus operating frequency, velocity, material accommodation factor was analyzed, and the gas squeeze film damping and pressure distribution was simulated by steady-state analysis or harmonic analysis. Moreover, pressure distribution of damping effect in plate gap both with perforated holes and without holes, were determined and compared. Simulation results show that operating frequency and the structure of microstructures are the main influencing factors to air damping and perforated holes in plate gap can control stiffness coefficients of squeezed film damping.

The Analysis of Squeezed Air-Damping on the Planar MEMS Structures

2005 ◽  
Author(s):  
X. Wang ◽  
M. Wang ◽  
Y. Liu
Keyword(s):  
Pressure Distribution ◽  
Reynolds Equation ◽  
Theoretical Models ◽  
Normal Direction ◽  
Squeeze Film ◽  
Film Model ◽  
Squeeze Film Damping ◽  
Air Damping ◽  
Air Film

Squeeze film damping of a planar micromechanical structure that oscillates in the normal direction to the substrate is investigated. Theoretical models influencing the squeeze film damping has been developed for the transversely oscillating plates. The air-film model has been derived from the modified nonlinear Reynolds equation, where the influence of the gas rarefaction is included. The performance of squeeze film such as the variation of the pressure distribution and the air damping load are analysed.

ANALYTICAL MODELING OF SQUEEZE FILM DAMPING IN DUAL AXIS TORSION MICROACTUATORS

2015 ◽  
Vol 22 (01) ◽  
pp. 1550006 ◽  
Author(s):  
HAMID MOEENFARD
Keyword(s):  
Pressure Distribution ◽  
Analytical Modeling ◽  
Reynolds Equation ◽  
Squeeze Film ◽  
Design Parameters ◽  
Modeling And Control ◽  
Squeeze Film Damping ◽  
Damping Torque ◽  
And Control ◽  
Selection Of

In this paper, problem of squeeze film damping in dual axis torsion microactuators is modeled and closed form expressions are provided for damping torques around tilting axes of the actuator. The Reynolds equation which governs the pressure distribution underneath the actuator is linearized. The resulting equation is then solved analytically. The obtained pressure distribution is used to calculate the normalized damping torques around tilting axes of the actuator. Dependence of the damping torques on the design parameters of the dual axis torsion actuator is studied. It is observed that with proper selection of the actuator's aspect ratio, damping torque along one of the tilting directions can be eliminated. It is shown that when the tilting angles of the actuator are small, squeeze film damping would act like a linear viscous damping. The results of this paper can be used for accurate dynamical modeling and control of torsion dual axis microactuators.

Dynamic behavior of perforated parallel-plate actuator under squeeze film damping effect

2015 ◽  
Vol 23 (2) ◽  
pp. 411-419 ◽  
Author(s):  
Weimin Wang ◽  
Fenggang Tao ◽  
Qiang Wang ◽  
Chuankai Qiu ◽  
Zexiang Chen ◽  
...  
Keyword(s):  
Dynamic Behavior ◽  
Parallel Plate ◽  
Squeeze Film ◽  
Damping Effect ◽  
Squeeze Film Damping

Simulation of the Squeeze Film Damping in a RF MEMS Switch

2013 ◽  
Vol 427-429 ◽  
pp. 116-119
Author(s):  
Xiang Guang Li ◽  
Qin Wen Huang ◽  
Yun Hui Wang
Keyword(s):  
Surface Pressure ◽  
Reynolds Equation ◽  
Dynamic Models ◽  
Mechanical Response ◽  
Rf Mems ◽  
Squeeze Film ◽  
Damping Force ◽  
Rf Mems Switch ◽  
Mems Switch ◽  
Squeeze Film Damping

Two different dynamic models have been presented to investigate the transient mechanical response of a RF MEMS switch under the effects of squeeze-film damping based on a modified Reynolds equation. Both the perforated and non-perforated structures are built for comparison. The models include realistic dimensions. The surface pressure, the damping force, and the tip displacement are simulated in three different ambient pressures, such as 500Pa, 5kPa, and 0.05MPa. The result shows that the increased damping leads to a substantial decrease in oscillation with increasing pressure for the non-perforated structure. Compared with the perforated pad, there is a much larger damping force acts on the non-perforated surface, and an obvious decrease in damping force with increasing pressure.

scholarly journals An Experiment to Determine the Accuracy of Squeeze-Film Damping Models in the Free-Molecule Regime

2007 ◽  
Author(s):  
Hartono Sumali
Keyword(s):  
Reynolds Equation ◽  
Damping Ratio ◽  
Laser Doppler Vibrometer ◽  
Squeeze Film ◽  
Free Molecule ◽  
Test Device ◽  
Squeeze Film Damping ◽  
Order Of Magnitude ◽  
Correct Boundary Conditions ◽  
The Continuum

Current published models for predicting squeeze film damping (SFD), which are based on different assumptions, give widely different results in the free-molecule regime. The work presented here provides experimental data for validating SFD models in that regime. The test device was an almost rectangular micro plate supported by beam springs. The structure was base-excited. The rigid plate oscillated vertically while staying parallel to the substrate. The velocities of the plate and of the substrate were measured with a laser Doppler vibrometer and a microscope. The damping ratio was calculated by performing modal analysis of the frequency response functions. The test structures were contained in a vacuum chamber with air pressures controlled to provide a five-order-of-magnitude range of Knudsen numbers. The damping coefficients from the measurements were compared with predictions from various published models. The results show that the continuum-base Reynolds equation predicts squeeze-film damping accurately if used with correct boundary conditions. The accuracy of molecular-based models depends heavily on the assumptions used in developing the models.

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