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 steadystate analysis or harmonic analysis. Stress and strain calculations, modal and buckling analyses, and frequency responses can all be performed with ease. Squeeze film air damping in mems, sensors and actuators a. Modeling technique of material damping properties in ansys. In conjunction with my masters thesis i am a concerned with a squeeze flow problem squeeze film damping of a sdof system. It seemed that i could only apply a constant global alpha damping by eddamp,all,c i tried to apply damping only to the beam to simulate the viscous squeeze film air damping to the beam, and i had created a part no. Improving the validity of squeeze film airdamping model of. This film region is modeled in ansys using 2d fluid 36 elements. To model the squeeze film damping using ansys, while considering the flexibility of the vibrating structure, we use fluid 6 elements to model the airfilm and solid 45 elements to model the structure. Keywords squeeze film damper, nonlinear force, cavitation, damping. Analytical solution of the modified reynolds equation for. The model includes effects of compressibility, inertia, and rarefaction in the flow between two parallel plates forming the squeeze region, as well as the flow through perforations. It seemed that i could only apply a constant global alpha damping by eddamp,all,c i tried to apply damping only to the beam to simulate the viscous squeezefilm air damping to the beam, and i had created a part no.
Theory this paper presents a methodology to simulate a 3d model of fluid film for finite length squeeze film damper using computational fluid dynamics cfd. Oct 27, 20 the fluid flow around a cantilever in an encasing. These treatments ignoring the border effect can not give. Feb 24, 2004 i applied damping to the model by eddamp command.
Perforations in microstructures are often used to control the squeezefilm damping in microresonators. In turn, the stiffness and damping due to all the patterns are summed up resulting in the stiffness and damping forces due to the entire squeeze film. Aug, 2009 associated with that flow is viscosity, which means that some of the kinetic energy of the moving surfaces gets dissipated. Full squeeze film damping, dynamic response to complex vibration inputs, shock analysis, and q factor calculations are equally easy to derive. Application of computational fluid dynamics simulation to.
Picture a gold beam that vibrates up and down and there are some holes that lets the air through. In order to deeply and systematically study these two issues, this paper proposes a typical verticallydriven inertial microswitch, wherein the air and electrode gaps were chosen to design the required damping ratio and threshold value, respectively. Squeezefilm damping and acceleration load are two major issues in the design of inertial microswitches. Squeeze film dampers sfds are a widely employed solution to the steadystate vibrations in highspeed turbomachinery. Cfd analysis of the squeeze film damping mechanism in the first stage of servovalves paolo tamburrano1,2, a, andrew r. Squeeze film gas damping of a vibrating disc application id. Download citation air damping effects of mems parallelplate structure using ansys thin film analysis ansys thin film analysis was adopted to simulate the effects of squeeze film damping. Jan 07, 2007 we present a new method for simulating squeeze film damping of microplates actuated by large electrostatic loads. The two flows are coupled through a nontrivial frequencydependent pressure. Moreover, pressure distribution of damping effect in plate gap both with.
Effect of flexural modes on squeeze film damping in mems. The paper presents an overview and reports the recent progress of research on squeeze film air damping in mems. Effect of flexural modes on squeeze film damping in mems cantilever resonators. Squeeze film dampers are widely applied in high rotating speed. Hello, i would like to use comsol to simulate the effects of squeeze film damping on an oscillating microcantilever in a closed body of fluid. Compact parallelplate squeezefilm models are verified using the experimental results and the simulation errors are confirmed to be lower than 20%. I have already used a squeeze film approximation fluid6 to obtain a damping ratio, which i can apply to a transient analysis to obtain the damped response. Analysis of finite length squeeze film damper using cfd. Micromachines free fulltext simulation study of inertial. Effects of squeezed film damping on dynamic finite element. Extraction of the mass normalized mode shapes and corresponding modal frequencies of the diaphragm is a first step in performing the squeeze film damping analysis and simulating dynamic frequency response functions in air. Air damping effects of mems parallelplate structure using ansys thin film analysis.
Film damping often occurs in microsystems when a released or freely moving structure is separated from the substrate a larger structure that is stationary by a thin layer of gas. But when i find some help in ansys, i only see squeeze film using cfd so, with cfx, how can i simulate the air acting with both stiffness and damping effect. Oct 20, 2017 exact and approximate solutions for transient squeezing flow. Improving the validity of squeeze film airdamping model of mems. Squeezefilm dampers sfds are a widely employed solution to the steadystate vibrations in highspeed turbomachinery.
The compact formula thus obtained for computing the squeeze film damping in mems cantilever resonators is valid for all flexural modes and beam geometries with a large range of aspect ratios. At microscale, the main damping source is the so called squeeze film air damping. After the basic effects of squeeze film damping on the dynamic performances of micro. Simulation of squeezefilm damping of microplates actuated. In the video the effect of double and single squeeze film damping is studied by examining how the fluid flow is altered. Mar 25, 2008 dynamic behaviour of oscillating perforated microplates under the effect of squeeze film damping is analyzed. The compact formula thus obtained for computing the squeeze film damping in mems cantilever resonators is valid for.
How to simulate squeeze film damping comsol multiphysics. Here, the equations are solved under steady state conditions with the. Simulation of squeezefilm damping of microplates actuated by. Squeezefilm damping plays a significant role in the performance of microresonators because it determines their quality factors. At microscale, the main damping source is the so called squeezefilm air damping. Simulation of thinfilm damping and thermal mechanical noise spectra for advanced micromachined microphone structures. Analytical solutions for the stiffness and damping.
Ansys thin film analysis was adopted to simulate the effects of squeeze film. This benchmark model computes the total force acting on a vibrating disc in the frequency and time domains and compares both results with expressions derived analytically. Study of squeeze film damping in a microbeam resonator based. Sfd and trying to find the damping coefficient of the sfd. This equation is linearized and transformed to the standard twodimensional diffusion equation using a simple mapping function.
The damping and spring forces thus obtained analytically are compared with those obtained from the fem simulations in ansys. The student community is a public forum for authorized ansys academic product users to share ideas and ask questions. Numerical and experimental comparison of mems suspended. The analytical solution is then obtained using greens function. For this reason, the analysis of thermohydrodynamic thd effects on. Download citation air damping effects of mems parallelplate structure using. May 01, 2007 the paper presents an overview and reports the recent progress of research on squeeze film air damping in mems. Evaluation of squeezed film air damping is critical in the design and control of dynamic mems devices. Compact parallelplate squeeze film models are verified using the experimental results and the simulation errors are confirmed to be lower than 20%.
For this reason, the analysis of thermohydrodynamic thd effects on the sfd damping properties is essential. It is, therefore, essential to effectively model the electromechanical coupling of the system and the damping effects to correctly predict the most important design characteristics of the resonator, namely, the resonant frequency and the quality factor. Cantilever squeeze film damping fluid flow youtube. In contrast, high damping may be preferable in some mems to mitigate their shock response and transient performance. I would like to realize how does the damping work in the ansys transient dynamic analysis, will the program setting a model to calculate. A macromodel for squeezefilm air damping in the free. Exact and approximate solutions for transient squeezing flow physics of fluids 29, 103606 2017. The damping and spring forces thus obtained analytically are compared with those obtained from the fem simulations. Based on the mc simulations and the analytical travelingtime distribution, a macromodel, which relates air damping directly with device dimensions and operation parameters, is constructed. The main functions are to cap rotor oscillations and to reduce dynamic forces. A threedimensional monte carlo mc simulation approach is developed for the accurate prediction of the squeezefilm air damping on microresonators in the freemolecule gas regime. Coventorware tutorial university of california, berkeley.
Squeezefilm damping characteristics of cantilever microresonators for higher modes of flexural vibration. Evaluation of squeezefilm damping effects in mems perforated. Squeeze film dampers are widely applied in high rotating speed machinery to reduce vibration, add damping and increase the stability of the system. Analytical modeling of squeeze air film damping of biomimetic. The results were calculated using a 2d thermal analogy in ansys. In the video the effect of double and single squeeze film damping is studied by examining how the fluid flow is. Fluid squeezed and sliding films squeezed and sliding films cause damping. Sfds contain a thin film of lubricant that is susceptible to changes in temperature. The squeezefilm damping in perforated structures is modelled using a modified reynolds equation that includes compressibility and rarefaction effect. Study of squeeze film damping in a microbeam resonator. Excellent agreement between the analytical and the numerical solutions is obtained, indicating the validity of the analytical approaches. Exact and approximate solutions for transient squeezing flow. Ansys damper ansys workbench catia to ansys youtube.
The relation of damping effects versus operating frequency, velocity, material accommodation factor was. This squeezed film model can be combined with a solid mechanical finiteelement model in order to perform dynamic fluidstructure interaction analyses for cases in which the above assumptions are valid. We present a comprehensive analytical model of squeezefilm damping in perforated 3d microelectromechanical system structures. Predicting aerodynamic damping through simulation is possible by. To model the perforation effects on the squeeze film damping, many analytical models have been proposed, however, most of the previous models have been concerned.
A threedimensional monte carlo mc simulation approach is developed for the accurate prediction of the squeeze film air damping on microresonators in the freemolecule gas regime. Modeling of material damping properties in ansys c. Evaluation of squeezed film air damping is critical in the design and control of. The traditional method of squeeze film dampers analysis usually involves a complicated calculation program that is limited to a simplified physical model. Xansys fluid damping fluid6 elements dear all, i am trying to use the fluid6 elements to model the squeeze film damping of a cantilever beam. I am working on squeeze film damper sfd and trying to find the damping coefficient of the sfd. Squeeze film damping and acceleration load are two major issues in the design of inertial microswitches. Simulation of thinfilm damping and thermal mechanical. An analytical model for squeezefilm damping of perforated. The effect of squeeze film damping on the response of microstructures have been studied extensively in the past.
Xansys view topic xansys struc how to apply damping. Read analytical modeling of squeeze air film damping of biomimetic mems directional microphone, journal of sound and vibration on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Exact and approximate solutions for transient squeezing. This is a standard example that we use because weve got a squeeze film damping model in ansys mechanical as well. Simulation of thinfilm damping and thermal mechanical noise. Then we describe squeeze film damping in torsion micromirrors along with basic effects and angle estimation. Associated with that flow is viscosity, which means that some of the kinetic energy of the moving surfaces gets dissipated. Two simplified finite element numerical approaches are adopted to predict damping and stiffness effects transferred from the surrounding ambient air to oscillating structures. The published squeezed film air damping models are generally derived from the analytical solutions of reynolds equation or its other modified forms under the supposition of trivial pressure boundary conditions on the peripheral borders. In this paper, we present an analytical model of squeeze air film damping of a perforated biomimetic mems directional microphone. Download from the customer portal under downloadsapplication. The analytical model presented here is derived using exact flexural mode shapes of a 2d cantilever elastic plate. It is related to the presence of a thin film of fluid usually air confined between two walls in relative normal movement, and becomes significant especially when the.
Squeeze film dampers sfds are used in highspeed turbomachinery to provide external damping to the system. Numerical modeling of the flow in the squeeze film dampers with oil. Effects of squeezed film damping on dynamic finite element analyses of mems daniel j. We also performed numerical simulation using ansyscfx. Improving the validity of squeeze film airdamping model.
Hi, i am trying to simulate squeeze film damping using cfx in ansys. I am going to do an squeeze film damping cfd online discussion forums. What i want to do now is to look at the change in damping as the beam undergoes a large transient deflection by using the multifield solver fluid142. The fluid field analysis software ansysflotran has been adopted to.
Article information, pdf download for numerical modeling of the flow in the squeeze film. To model the perforation effects on the squeezefilm damping, many analytical models have been proposed, however, most of the previous models have been concerned. Xansys view topic xansys fluid damping fluid6 elements. The method enables the prediction of the quality factors of microplates under a limited range of gas pressures and applied electrostatic loads up to the pullin instability. In order to achieve this excitation, the two shakers are. Ansys thin film analysis was adopted to simulate the effects of squeeze film damping. Air damping effects of mems parallelplate structure using. There is a great need for accurate, yet computationally.
Apr 16, 2011 hello, i would like to use comsol to simulate the effects of squeeze film damping on an oscillating microcantilever in a closed body of fluid. Powerful visualization tools coupling with ode models. The squeeze film damping dynamics in microphone structures are captured by the reynolds squeeze film equation. Squeeze film simulations and dynamic response measurements in air. The first term of the formula is the material damping, how to define this term and whats meaning of this term. Air damping effects of mems parallelplate structure using ansys.
Dynamic behaviour of oscillating perforated microplates under the effect of squeeze film damping is analyzed. Aug 04, 2016 read analytical modeling of squeeze air film damping of biomimetic mems directional microphone, journal of sound and vibration on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. The squeeze film damping is the result of the movement of the fluid resisted by its viscosity that causes the fluid act as a spring and a damping force. We present a new method for simulating squeezefilm damping of microplates actuated by large electrostatic loads.
Numerical modeling of the flow in the squeeze film dampers. After the basic effects of squeeze film damping on the dynamic performances of microstructures. The traditional method of squeeze film dampers analysis usually involves a complicated calculation program that is. The developed model derives its main advantage from its. The microphone design is novel because it takes advantage of squeeze air film damping to enhance the direction sensitivity cues. In this case, the navierstokes equations governing the fluid flow can be reduced to a scalar equation in terms of the fluid pressure.
When the vibration amplitude is small enough that the system is linear the frequency and time domain. A compact squeezefilm model including inertia, compressibility. Analytical modeling of squeeze air film damping of. Ansys spaceclaim modeling and transient structural fea of camshaftrockervalve assembly duration. Gas damping must be minimized to achieve high sensitivity of mems, such as resonators. Are the alpha damping and beta damping related to frequency or independently.
Since the body is closed, the fluid displaced by the microcantilever as it moves down pushes on the top of the cantilever. Effects of squeezed film damping on dynamic analyses of mems. Effects of squeezed film damping on dynamic analyses of. Perforations in microstructures are often used to control the squeeze film damping in microresonators.
Squeeze film damping plays a significant role in the performance of microresonators because it determines their quality factors. Fluid damping can also be modeled using ansys cfd tools. Dec 10, 2014 squeeze film dampers sfd are applied to provide damping at the outer ring of ball bearings used in jet engines. Coventorware tutorial presented by brian pepin 11072011. I am working on squeeze film damper sfd and trying to find. Squeezefilm dampers sfd are applied to provide damping at the outer ring of ball bearings used in jet engines. A new test rig was designed to allow an orbital motion of the rotor shaft excited by two independently controllable electromagnetic shakers. Computational fluid dynamics cfd simulation is a highly effective tool to predict the performance of sfds and obtain design guidance. Squeeze film with cfx cfd online discussion forums.
289 806 422 969 402 802 1155 271 1113 342 429 654 894 785 358 407 754 1089 324 1074 1199 325 1364 747 1164 525 577 83 801 895 1258 576 739 1141