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Hybrid Elements for Modelling Squeeze Film Effects Coupled with Structural Interactions in Vibratory MEMS Devices

Roychowdhury, A and Nandy, A and Jog, CS and Pratap, R (2015) Hybrid Elements for Modelling Squeeze Film Effects Coupled with Structural Interactions in Vibratory MEMS Devices. In: CMES-COMPUTER MODELING IN ENGINEERING & SCIENCES, 103 (2). pp. 91-110.

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Official URL: http://dx.doi.org/10.3970/cmes.2014.103.091

Abstract

We present a hybrid finite element based methodology to solve the coupled fluid structure problem of squeeze film effects in vibratory MEMS devices, such as gyroscopes, RF switches, and 2D resonators. The aforementioned devices often have a thin plate like structure vibrating normally to a fixed substrate, and are generally not perfectly vacuum packed. This results in a thin air film being trapped between the vibrating plate and the fixed substrate which behaves like a squeeze film offering both stiffness and damping. For accurate modelling of such devices the squeeze film effects must be incorporated. Extensive literature is available on squeeze film modelling, however only a few studies address the coupled fluid elasticity problem. The majority of the studies that account for the plate elasticity coupled with the fluid equation, either use approximate mode shapes for the plate or use iterative solution strategies. In an earlier work we presented a single step coupled methodology using only one type of displacement based element to solve the coupled problem. The displacement based finite element models suffer from locking issues when it comes to modelling very thin structures with the lateral dimensions much larger than the plate thickness as is typical in MEMS devices with squeeze film effects. In this work we present another coupled formulation where we have used hybrid elements to model the structural domain. The numerical results show a huge improvement in convergence and accuracy with coarse hybrid mesh as compared to displacement based formulations. We further compare our numerical results with experimental data from literature and find them to be in good accordance.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the TECH SCIENCE PRESS, 6825 JIMMY CARTER BLVD, STE 1850, NORCROSS, GA 30071 USA
Keywords: squeeze film; hybrid; FEM; coupled
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Division of Interdisciplinary Research > Centre for Nano Science and Engineering
Depositing User: Id for Latest eprints
Date Deposited: 24 Apr 2015 06:23
Last Modified: 24 Apr 2015 06:23
URI: http://eprints.iisc.ac.in/id/eprint/51410

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