The ansys fea software package contains semiautomated tools for simulation of such systems, including the multiphysics solver, the essolv macro, and the rom144, trans126, and trans109 elements. The squeeze film damping dynamics in microphone structures are captured by the reynolds squeeze film equation. Zaxis micromachined tuning fork gyroscope with low air. An analytical model for squeezefilm damping of perforated. Simulation of thinfilm damping and thermal mechanical noise. Analysis of finite length squeeze film damper using cfd. 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. Finite element analysis of cmuts with pressurized cavities. This video shows how to model moving and deforming mesh examples in ansys fluent. This paper reports on the design and fabrication of a zaxis tuning fork gyroscope which has a freestanding architecture. Analytical investigation of squeeze film dampers, is hereby. The proposed architecture was analyzed by the finite element method using ansys software. In slide film damping, the released structure moves parallel to the substrate, leading to shearing within the gas film.
Government users, except as specifically granted by the ansys, inc. I am the student community is a public forum for authorized ansys academic product users to share ideas and ask questions. We present a new method for performing a finite element analysis for such structures using ansys. When the vibration amplitude is small enough that the system is linear the frequency and time domain. Nov 12, 2016 a subcritical or supercritical rotor is often employed to improve the energy storage efficiency of flywheel systems. Pdf viscous damping influence on dynamic characteristics. The modal analysis and campbell plot may be accessed directly from the ansys mechanical.
That is, the film surface must have one moving plate and one fixed base plane. Numerical modeling of the flow in the squeeze film dampers with oil. Analytical modeling of squeeze air film damping of biomimetic. Analysis of finite length squeeze film damper using cfd ijltet. In the mentioned gyroscope performance, air damping is considered to be the dominant damping mechanism which includes slidefilm damping and squeezefilm damping. At microscale, the main damping source is the so called squeeze film air damping.
Simulation of thinfilm damping and thermal mechanical noise spectra for advanced micromachined microphone structures. Our renewable products can be downloaded by students across the globe. Air damping effects of mems parallelplate structure using. A multiphysics finiteelement model built using the software ansys is utilized for the fluidic and transient structural analysis. Rotordynamic design analysis of a squeeze film damper test rig. Squeezefilm damping and acceleration load are two major issues in the design of inertial microswitches. In the implementation of squeezed film damping analysis in intellisuite, the base plane must be fixed in space. In such cmuts, a squeeze film is formed between the plate and the substrate, which provides additional damping as well as stiffening. 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.
Each tool has specific strengths, but none is without problems. Harmonic response analysis is performed to verify the results using the fem software ansys. The microphone design is novel because it takes advantage of squeeze air film damping to enhance the direction sensitivity cues. Viscous damping influence on dynamic characteristics in. 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. Dynamic analysis for the energy storage flywheel system. The damping from the squeeze film helps increase the bandwidth of the cmut. Several commercial software packages are available for performing finite. Effects of squeezed film damping on dynamic finite element analyses of mems daniel j. The traditional method of lubrication analysis of squeeze film dampers.
Effect of flexural modes on squeeze film damping in mems cantilever. Jan, 2015 fluid squeezed and sliding films squeezed and sliding films cause damping. Past measurements of the squeeze film damper force characteristics have been carried out at squeeze film. Simulation study of inertial microswitch as influenced by. Squeezefilm damping plays a significant role in the performance of microresonators because it determines their quality factors. Evaluation of squeezefilm damping effects in mems perforated. The squeeze film damper over four decades of investigations.
In this paper, we present an analytical model of squeeze air film damping of a perforated biomimetic mems directional microphone. 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. Ansys student products can be installed on any supported ms windows 64bit machine. Mems variable capacitor using ansys software are studied. I would like to realize how does the damping work in the ansys transient dynamic analysis, will the program setting a model to calculate.
Specifically, you will learn how to utilize coupled physics simulation tools for common mems devices, such as thermalelectric actuators, comb drive resonators, micro mirrors, switches and piezoelectric actuators. 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. In order to deeply and systematically study these two issues, this paper proposes a typical verticallydriven inertial microswitch, wherein the. The student community is a public forum for authorized ansys academic product users to share ideas and ask questions. These treatments ignoring the border effect can not give. Zaxis micromachined tuning fork gyroscope with low air damping. Picture a gold beam that vibrates up and down and there are some holes that lets the air through.
This paper presents a methodology to simulate a 3d model of fluid film for finite length squeeze film damper using computational fluid dynamics cfd. Aug, 2009 associated with that flow is viscosity, which means that some of the kinetic energy of the moving surfaces gets dissipated. Any squeeze film application can benefit from this technology, including thin film fluid damping often found in rf mems switches. System damping ratio analysis of a capacitive micromechanical. A squeeze film damping model, for both the air underneath the structure and the flow of the air through the perforations, is developed. Improving the validity of squeeze film airdamping model. A subcritical or supercritical rotor is often employed to improve the energy storage efficiency of flywheel systems.
This film region is modeled in ansys using 2d fluid 36 elements. Damping coefficient, c, is multiplied by the velocity to get the force, right. Sfd and trying to find the damping coefficient of the sfd. Are the alpha damping and beta damping related to frequency or independently. In order to improve the performance of the tuning fork gyroscope by eliminating the influence of the squeeze film air damping, the driving and sensing parts of the gyroscope were designed to oscillate inplane. The optimal design of the tuning fork gyroscope is carried out by simulating its mechanical behavior with the finite element method fem using ansys software. 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. This is a standard example that we use because weve got a squeeze film damping model in ansys mechanical as well. Livecore ansys training courses is an american computeraided engineering software developer. The traditional method of squeeze film dampers analysis usually involves a complicated calculation program that is limited to a simplified physical model. Passive damping treatment is one of the methods to control the noise and vibration in. Consequently, it is necessary to introduce squeeze film dampers sfd in the rotorbearing system to suppress the lateral vibration of the rotor. According to the squeezefilm damping coefficient of a rectangle, the systemdamping coefficient is related to the width and length of proof mass and the gap between glass and mass. Analytical modeling of squeeze air film damping of.
The first term of the formula is the material damping, how to define this term and whats meaning of this term. Ansys, core layers, damping, modal analysis, sandwich beam 1. Fluid squeezed and sliding films squeezed and sliding films cause damping. In conjunction with my masters thesis i am a concerned with a squeeze flow problem squeeze film damping of a sdof system.
We use the exact mode shapes of a 2d cantilever plate to solve for pressure in the squeeze film and then derive the equivalent damping and spring coefficient relations from the back force. You should take this course if you have a need to analyze mems devices using ansys. 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 thickness of the air layer is at least one third of the wall size. Since the body is closed, the fluid displaced by the microcantilever as it moves down pushes on the top of the cantilever. In a typical capacitive detection gyroscope, wh ere a combtype detection structure is commonly used, the squeezefilm air dampin g and the slidefilm air damping between the proof masses and the.
At microscale, the main damping source is the so called squeezefilm air damping. Compact parallelplate squeeze film models are verified using the experimental results and the simulation errors are confirmed to be lower than 20%. Ansys thin film analysis was adopted to simulate the effects of squeeze film damping. The method enables the prediction of the quality factors of microplates under a. Squeeze film dampers are widely applied in high rotating speed machinery to. Results are shown for various models of squeeze film damping assuming no holes. Furthermore, by removing the substrate underneath the device, the slide. Squeeze film dampers are widely applied in high rotating speed machinery to reduce vibration, add damping and increase the stability of the system. Moreover, pressure distribution of damping effect in plate gap both with. Ansys cfx software was used for solving the pressure and velocity.
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. Passive damping treatment is one of the methods to control the noise and vibration in structures. Modeling technique of material damping properties in ansys. Nguyen quang long postdoctoral researcher dtu nanolab. 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.
Ansys workbench project schematic makes the process crystal clear. Hi, i am trying to simulate squeeze film damping using cfx in ansys. If you have the appropriate software installed, you can download article. I am working on squeeze film damper sfd and trying to find the damping coefficient of the sfd. The squeezed film model, in turn, provides the resulting fluid pressure on the moving plate to the solid mechanical model. 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.
I am working on squeeze film damper sfd and trying to find. There is fluid air between the beam and a fixed wall. Although the dynamic behavior of the rotorbearing system can be investigated in a timely manner with ansys software, it is difficult. Ansys publishes engineering analysis software across a range of disciplines including finite element. Squeeze film damping and acceleration load are two major issues in the design of inertial microswitches. How to simulate squeeze film damping comsol multiphysics. 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. Effects of squeezed film damping on dynamic analyses of.
Pdf simulation of squeezefilm damping of microplates. We present a new method for simulating squeeze film damping of microplates actuated by large electrostatic loads. Compact parallelplate squeezefilm models are verified using the experimental results and the simulation errors are confirmed to be lower than 20%. Perforations in microstructures are often used to control the squeezefilm damping in microresonators. Squeeze film gas damping of a vibrating disc application id. Dynamic characteristics of movable electrode in mems variable capacitor using ansys software are studied. Xansys view topic xansys fluid damping fluid6 elements. Mar 14, 2018 this video shows how to model moving and deforming mesh examples in ansys fluent. Viscous damping influence on dynamic characteristics in mems. Among them, the effect of air damping is considered as the primary loss mechanism for the device, which operates in atmospheric conditions. Ii squeezefilm damping for structures in which only the size of the small gap between two plates changes in time, the pressure changes p relative to the wall velocity are described by the reynolds equation 9.
Introduction damping has a very high importance in structures and systems subjected to dynamic loading. The simulated frequencies of the driving and sensing modes were 9. Here, the equations are solved under steady state conditions with the commercial software ansys14. This work is focused on viscous damping influence on dynamic characteristics. Perform squeezefilm damping analysis using fluid6, fluid8. Jun 04, 2008 a multiphysics finiteelement model built using the software ansys is utilized for the fluidic and transient structural analysis. Analyzing vibration with acoustic structural coupling ansys. Squeeze film simulations and dynamic response measurements in air. Ansys is a worldleading developer of simulation solutions for all areas of engineering physics.
It is discovered that significant contribution to the vibration system damping is introduced by squeezefilm damping between serpentine spring arms. I am going to do an squeeze film damping cfd online discussion forums. 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. Keywords squeeze film damper, nonlinear force, cavitation, damping. Improving the validity of squeeze film airdamping model of. Effect of flexural modes on squeeze film damping in mems. The lateral damping coefficient can be expressed as.
The paper presents an overview and reports the recent progress of research on squeeze film air damping in mems. When the gap contracts, the gas film is squeezed between the two surfaces. We present a new method for simulating squeezefilm damping of microplates actuated by large electrostatic loads. Effects of squeezed film damping on dynamic analyses of mems. Modeling of material damping properties in ansys c. Characterization of the dynamical response of a micromachined. Numerical modeling of the flow in the squeeze film dampers. For any questions or to learn more visit the ansys student community. So if you do the 2way fsi and solve for the motion, you will get the velocity, then c f v. Slidefilm damping, or lateral damping, occurs when two plates of an area a, separated by a distance d, slide parallel to each other. Squeeze film with cfx cfd online discussion forums. Simulation of thinfilm damping and thermal mechanical. 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.
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