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