Air damping of oscillating mems structures comsol multiphysics. The movement of the air can be either forced, via a fan, or free, as a result of the natural buoyancy variations due to changes in the air temperature. Multiphysics analysis of thermoelastic damping effects on rf. Simulating a permanent magnet in solidworks with ems by emworks. How to model different types of damping in comsol multiphysics. Warning your internet explorer is in compatibility mode and may not be displaying the website correctly. Comsol multiphysicstm was previously used successfully for air damping simulations in angular combdrive micromirrors. Thinfilm thickness influence on anisotropic mems damping.
I was very happy to calculate the damping loss rather than wander around trying random values for damping loss in comsol. It needs to vibrate with a high qfactor in the horizontal plane and a low one along the transverse plane 4. The simulationbased results on vibration and acoustics analysis are very sensitive to the description and input methods of damping properties. The resulting model includes some of the most advanced air and gas damping mechanisms that comsol multiphysics has to offer. The comsol software employs an iterative procedure to solve the resulting discrete, nonlinear algebraic system of equations that result from the finite element approximation of the navierstokes equations. Comsol multiphysicstm was previously used successfully for air damping simulations in angular combdrive micromirrors 4. Comsol multiphysics and comsol are either registered trademarks or trademarks of comsol ab. Modeling and simulation of damping resistance of a cantilever. Evaluation of squeezefilm damping effects in mems perforated. Comsol multiphysics software is used for applications that have coupled physics problems and is a unique tool that is used for the designing and analysis phase of the magnetorheological damper. This might be a question better suited for the software recommendations side of s. In the present paper, we apply both the main analytical models and a commercial finite. Comsol software to define the dimensionless elastic and viscous damping.
In this paper, the consideration of vibration damping using software. To evaluate the applicability of the fluidstructure interaction interface of comsol multiphysicstm for estimation of the air damping for a variety of other mems devices, the experimental and simulated. Comsol multiphysics is a crossplatform finite element analysis, solver and multiphysics simulation software. The simulation process begins by building up geometry of the room, assigning constant parameters, meshing the geometry of the room, and finally run the solver analysis. In both cases, when meshing these models, automatic mesh refinement resolves the shock pattern by refining around the regions with very high velocity and pressure gradients. Excessive air damping can be detrimental to the performance. Cfd software for simulating fluid flow applications.
For instance, the thermoviscous acoustics, transient interface generates the full details for the viscous and thermal damping of the micromirror from the surrounding air. The slits are narrow enough that the socalled viscothermal effects are of significant importance. School of mechanical engineering, university of birmingham, edgbaston, b15 2tt. Comsol multiphysics is an engineering, design, and finite element analysis software environment for the modeling and simulation of any physicsbased system. The analysis results are presented and compared with microphone structure having perforated back plate. The effect of different air gap height on the damping was also studied. Dec 29, 2011 the literature includes a variety of analytical and semianalytical models to describe squeezefilm damping in mems perforated structures. Pdf modeling and simulation of mr damper using comsol. The measured air velocity then used as an input in simulation work which used comsol multiphysics. Discussion closed this discussion was created more than 6 months ago and has been closed. Modeling technique of material damping properties in ansys.
This model of a vibrating micromirror surrounded by air uses the thermoacousticshell interaction user interface to model the fluidsolid interaction, and it thus includes the correct viscous and thermal damping of the mirror from the surrounding air. For high squeeze number, typical for cmut operation, air spring constants for piston and flexible membrane are similar. In acoustics, knowing the damping properties of fluids and structures can be challenging. Mufflers are often located in exhaust systems or on heat, ventilation, and air conditioning hvac systems, where their key functionality is to. You can use the specialized features to visualize acoustic fields and build virtual prototypes of devices or. Comsol multiphysics is compatible with windows xp7810 environment, 32 and 64bit versions.
Excessive air damping can be detrimental to the performance of oscillating. In order for the motion to be periodic, the damping ratio must be limited to the range 0 \le \zeta air and gas damping mechanisms that comsol multiphysics has to offer. Comsol provides an ide and unified workflow for electrical, mechanical, fluid, acoustics and chemical applications. See firsthand how the comsol software works in an interactive online demo tailored to discuss your needs. It allows conventional physicsbased user interfaces and coupled systems of partial differential equations pdes. Simulation of surface pressure distribution and damping analysis was carried out for different mirror plate materials. This software was originally produced by comsol ab. From the analysis it is clear that at some particular. The comsol software automatically formulates the energy equation coupled to the momentum and mass balance equations for ideal gases. Yang 1 the damping effect of enveloping air would be. In a second part, we propose a numerical approach based on the fem multiphysics comsol software to define the dimensionless elastic and viscous damping forces in circular cmut with flexible plate.
The effect of resonance frequency by changing the torsional spring on air damping is investigated. The proposed structure is modeled and studied using comsol multiphysics software. Even if many of them have been validated by means of numerical simulations, nobody seems to have discussed about the accuracy of numerical approaches in this field. The analysis result are presented and compared with microphone structure having perforated back plate. This discussion is about an older version of the comsol multiphysics software. The version of lmgrd must be the same or higher than the flexnet version used by the comsol software. Numerical solutions are obtained by full 3d navierstokes numerical analysis, carried out by a commercial finite element code, comsol multiphysics. Viscous damping and spring force calculation of regularly.
Mems microphone, corrugated diaphragm, perforated diaphragm 1. Excessive air damping can be detrimental to the performance of oscillating mems components. Classical hydraulic dampers are flexible devices that are used to attach a component to a mounting base. The combination of comsol products required to model your application depends on several. I am looking for a free not only as in freedom alternative to comsol multiphysics. Squeeze film air damping analysis is done on the fixedfixed beam membrane for. Complex systems, such as structures in preetched cavities or angular combdrive scanning mirrors, typically require simulations to reliably evaluate the air damping. This means that the comsol license server needs to be upgraded to comsol 5. The comsol software automatically detects the solidfluid boundary and applies the necessary boundary conditions at the solidfluid interface.
Oct 15, 20 the total viscous damping of a cell consists of the squeezefilm damping due to the motion of the air in the gap and the resistance of the hole. Solution below, you can see a table with the first and fourth natural frequencies in khz of beams in vacuum, air, and water. In the comsol multiphysics software any number of physics can be combined in one and the same simulation. Explicit specification of damping constant posted 21. Viscous damping and spring force in periodic perforated. Vibration amplitude reduction can be achieved by improving the old technique of suspension by bringing in application of magnetorheological or electrorheological fluid in it.
Air damping significantly influences the dynamical characteristics of. Thermal management of buildings hardware and simulation software modeling. Comsol webinar modeling coils and electric devices youtube. The most popular versions among comsol multiphysics users are 4. Using comsol multiphysics, it is possible to estimate your material parameters from experimental measurements through optimization.
A compression driver is a certain type of electrodynamic loudspeaker which has a phase plug with slits in front of the diaphragm. The majority of mems microphones use flat diaphragms along with a perforated back plate. Apr 28, 2017 whenever we have a heated or cooled part exposed to air, there is some transfer of heat from the part to the air via convection. Mems micromirror oszillation air damping comsol multiphysics. Analysis of squeeze film air damping in fixedfixed beam rf mems. Mar 19, 2018 watch this webinar to get a 20minute introduction to vibration and noise analysis in comsol multiphysics and learn about modeling acoustic applications like gearbox systems, gear trains. The present study is aimed to predict the damping measured as qfactor of a single mass cantilever energy harvester structure as shown in figure 1 at various cavity pressure using comsol multiphysics commercial finite element software. In this paper, squeeze film damping analysis was performed on a micromirror using comsol multiphysics software. I was able to find the damping loss to introduce in comsol based on quality factor given in my piezoelectric harvester specifications.
Squeeze film damping and stiffening in circular cmut with air. In this paper, analytical and numerical methods for simulating squeezefilm air damping affecting suspended and perforated movable microsurfaces are analyzed. The measured air velocity then used as an input in simulation work which used comsol multiphysics software. Simulation software for analyzing acoustics and vibrations. Modeling and simulation of mr dampers using comsol. Comsol webinar vibration and noise analysis in comsol. The measurement of air velocity was taken using davis anemometer at random point in the room. Simulation of room airflow using comsol multiphysics software. In order to decrease the total viscous damping, a larger hole density is required. There are many types of structural damping that you can implement in your finite element analyses. For porous materials, the challenge may be even higher, as data provided by manufacturers is often sparse. Magnetic field comsol multiphysics modeling software. Comsol software users who are onsubscription should submit their questions via the support center for a more comprehensive response from the technical support team. Micromirrors are used in certain mems devices to control optic elements.
Vibrating micromirror with viscous and thermal damping. Squeezefilm gas damping of a vibrating disc comsol. How do i make a nonlinear solver converge in comsol multiphysics. Analyze viscous and thermal damping in a vibrating micromirror with. Iiii complex 3d geometry construction using basic mathematics l7 duration. In order for the motion to be periodic, the damping ratio must be limited to the range 0 \le \zeta comsol conference in cambridge air damping simulation of mems torsional paddle n. Modeling acoustic damping processes comsol multiphysics. Air damping analysis in comb microaccelerometer wu zhou, yu. Since the absence of accurate measuring technologies makes it impossible to acquire the real structural parameters of sensing capacitors, the comsol software and whole sensor tests are proposed in this paper to study the dependence of damping coefficients on the fabrication errors including dimension deviation and etching angle. Comsol multiphysics alternatives and similar software.
Analyzing the viscous and thermal damping of a mems. Modeling natural and forced convection in comsol multiphysics. Damping effect of enveloping air is enforced if a plate is oscillating close to another plate, so that the air film is squeezed in between the two surfaces. In a second part, we propose a numerical approach based on the fem multiphysics. Design and multiphysics analysis of mems capacitive microphone. Compression driver simulation including air damping in. A homogeneous, unstructured mesh was employed for most of the domain with areas of refinement in the gap region and around the reentrant. Analyzing the viscous and thermal damping of a mems micromirror. The combination of comsol products required to model your application. Various mems devices, resonators and sensors are designed to operate in air and viscous fluids. Analytical and numerical modeling of squeezefilm damping in. Multiphysics modeling of mems devices november 20 executive summary power is increased with dedicated tools.
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