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squeeze-film-damping
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Dynamics Modeling of new Scratch-drive Actuators with Bounce back Mechanism (BSDA)
, M.Sc. Thesis Sharif University of Technology ; Vossughi, Gholamreza (Supervisor) ; Meghdari, Ali (Supervisor)
Abstract
In recent decades, micro-electromechanical systems – MEMS – havefound extensive applications in applied science and engineering. One of the most popular MEMS actuatorsis micro Scratch Drive Actuator (SDA), which can be used in various applications, for instance: precision positioning, micro-chip displacement and rotating micromotors. Their outstanding capabilities such as: high controllability, precise step displacement, vast transportation domain and large force relative to their small size, have made them popular among researchers. Recently, a new generation of SDA is introduced, known as Bounce-back Scratch Drive Actuator or BSDA, which is fundamentally different in motion generation from...
Coupled bending and torsion effects on the squeezed film air damping in torsional micromirrors
, Article Proceedings of the ASME Design Engineering Technical Conference, 12 August 2012 through 12 August 2012 ; Volume 5 , August , 2012 , Pages 49-55 ; 9780791845042 (ISBN) ; Kaji, F ; Ahmadi, M. T ; Sharif University of Technology
2012
Abstract
The current paper presents an analytical model for the problem of squeezed film damping in micromirrors considering the bending of the supporting torsion microbeams. At the first the nonlinear Reynolds equation governing the behavior of the squeezed gas underneath the mirror is linearized. The resulting linearized equation is then nondimensionalized and analytically solved for two cases of the infinitesimal and finite tiling angle of the mirror. The obtained pressure distribution from the solution of the Reynolds equation is then utilized for finding the squeezed film damping force and torque applied to the mirror. The results show that in the case of the infinitesimal tilting angle, the...
Developing a new pressure measurement mechanism based on squeeze film damping effect
, Article Proceedings - 2011 2nd International Conference on Control, Instrumentation and Automation, ICCIA 2011, 27 December 2011 through 29 December 2011 ; Dec , 2012 , Pages 800-803 ; ISBN: 9781467316897 ; Ghanbari, A ; Kamanzadeh, S ; Abbasian, K ; Saghir, H ; Sharif University of Technology
IEEE Computer Society
2012
Abstract
This paper introduces a novel approach for measuring low pressures based on MEMS technology. In this technique the mechanism of squeeze film damping is used. A voltage is applied to a fixed-fixed MEMS beam and its step response is obtained; for each pressure there is a different response. Then the settling time is measured and we can relate each settling time with a defined pressure. Here, first we use some equations to relate pressure with the squeeze film damping effect; after that we use a micro beam model and relate its parameters with pressure. Then we use numerical analysis and simulation to show the procedure of pressure measuring. All simulation results are shown and discussed
Dynamics of multi layer microplates considering nonlinear squeeze film damping
, Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 1096665X (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) ; Moghimi Zand, M ; Borhan, H ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006
Abstract
This paper presents a model to analyze pull-in phenomenon and dynamics of multi layer microplates using coupled finite element and finite difference methods. Firstorder shear deformation theory is used to model dynamical system using finite element method, while Finite difference method is applied to solve the nonlinear Reynolds equation of squeeze film damping. Using this model, Pull-in analysis of single layer and multi layer microplates are studied. The results of pull-in analysis are in good agreement with literature. Validating our model by pull-in results, an algorithm is presented to study dynamics of microplates. These simulations have many applications in designing multi layer...
Effect of geometric nonlinearity on dynamic pull-in behavior of coupled-domain microstructures based on classical and shear deformation plate theories
, Article European Journal of Mechanics, A/Solids ; Volume 28, Issue 5 , 2009 , Pages 916-925 ; 09977538 (ISSN) ; Moghimi Zand, M ; Ahmadian, M. T ; Sharif University of Technology
2009
Abstract
This paper investigates the dynamic pull-in behavior of microplates actuated by a suddenly applied electrostatic force. Electrostatic, elastic and fluid domains are involved in modeling. First-order shear deformation plate theory and classical plate theory are used to model the geometrically nonlinear microplates. The equations of motion are descritized by the finite element method. The effects of nonlinearity, fluid pressure, initial stress and different geometric parameters on dynamic behavior are examined. In addition, the influences of initial stress and actuation voltage on oscillatory behavior of microplates are evaluated. © 2009 Elsevier Masson SAS. All rights reserved
Nonlinear Vibration and Pull-in Analysis in Electrostatically Actuated Dual Axis Micromirrors
, M.Sc. Thesis Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Firoozbakhsh, Keykhosro (Supervisor)
Abstract
In recent decades, the important role of MEMS devices in optical systems has initiated the development of a new class of MEMS called Micro-Opto-Electro-Mechanical Systems (MOEMS), which torsional micromirror is one of these systems. Among variety kinds of micromirrors the dual axis micromirror has hopefully application such as high quality projection display, free-space fiber optical (FSO) communications and endoscopic optical coherence topography. Dual axis micromirror could play a key role in FSO applications such as satellite-to-satellite separated by hundreds of kilometers, as where. In medical applications, micromirror must could be able to rotates θ_x and θ_y.about two axis x and...
Nonlinear Vibration and Pull-in Analysis in Electrostatically Actuated Nano/Micromirrors
, Ph.D. Dissertation Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor)
Abstract
The important role of MEMS devices in optical systems has initiated the development of a new class of MEMS called Micro-Opto-Electro-Mechanical Systems (MOEMS), which mainly includes nano/micromirrors and torsional nano/microactuators. These devices have found variety of applications in optical switches, displays, micro scanning mirrors, optical cross-connects, interferometery, spectroscopy, aberration correction and biomedical imaging. In this project, the static and dynamic behavior of electrostatic nano/micromirrors under the effect of intermolecular surface forces and squeezed film damping are studied. The prior art published in the literature have mainly used pure torsion models. In a...
Mechanical Behavior Analysis of Biological Cells Using an Electrostatically Actuated Microbeam
, M.Sc. Thesis Sharif University of Technology ; Firoozbakhsh, Keikhosrow (Supervisor)
Abstract
Researches in last decades have shown that biological cell’s functionality is related to the way of their deformation in response to forces and stresses exerted on the cell. Therefore designing microsensors with easy and economical applicationswhich are capable for determining cell mechanical properties seems to be logical. In this project using an electrostatically actuated microbeam with both clamped ends equipped with an indenter at midpoint to transmit force on the cell, proposed as a technique to apply axial load on the cell. Inthis research by implementation of approximated methods for solving nonlinear algebraic and differential equations, governing on microbeam deflection, it has...
Effects of the van der Waals force, squeeze-film damping, and contact bounce on the dynamics of electrostatic microcantilevers before and after pull-in
, Article Nonlinear Dynamics ; Vol. 77, issue. 1-2 , 2014 , p. 87-98 ; Vossoughi, G ; Meghdari, A ; Sharif University of Technology
Abstract
The operational range of microcantilever beams under electrostatic force can be extended beyond pull-in in the presence of an intermediate dielectric layer. In this paper, a systematic method for deriving dynamic equation of microcantilevers under electrostatic force is presented. This model covers the behavior of the microcantilevers before and after the pull-in including the effects of van der Waals force, squeeze-film damping, and contact bounce. First, a polynomial approximate shape function with a time-dependent variable for each configuration is defined. Using Hamilton's principle, dynamic equations of microcantilever in all configurations have been derived. Comparison between modeling...
Dynamic pull-in instability and vibration analysis of a nonlinear microcantilever gyroscope under step voltage considering squeeze film damping
, Article International Journal of Applied Mechanics ; Volume 5, Issue 3 , September , 2013 ; 17588251 (ISSN) ; Ahmadian, M. T ; Firoozbakhsh, K ; Sharif University of Technology
2013
Abstract
In this paper, a nonlinear model is used to analyze the dynamic pull-in instability and vibrational behavior of a microcantilever gyroscope. The gyroscope has a proof mass at its end and is subjected to nonlinear squeeze film damping, step DC voltages as well as base rotation excitation. The electrostatically actuated and detected microgyroscopes are subjected to coupled flexural-flexural vibrations that are related by base rotation. In order to detune the stiffness and natural frequencies of the system, DC voltages are applied to the proof mass electrodes in drive and sense directions. Nonlinear integro differential equations of the system are derived using extended Hamilton principle...
Modeling squeezed film air damping in torsional micromirrors using extended Kantorovich method
, Article Meccanica ; Volume 48, Issue 4 , 2013 , Pages 791-805 ; 00256455 (ISSN) ; Ahmadian, M. T ; Farshidianfar, A ; Sharif University of Technology
2013
Abstract
The current paper uses the Extended Kantorovich Method (EKM) to analytically solve the problem of squeezed film damping in micromirrors. First a one term Galerkin approximation is used and following the extended Kantorovich procedure, the solution of the Reynolds equation which governs the squeezed film damping in micromirrors is reduced to solution of two uncoupled ordinary differential equation which can be solved iteratively with a rapid convergence for finding the pressure distribution underneath the micromirror. It is shown that the EKM results are independent of the initial guess function. It is also shown that EKM is highly convergent and practically one iterate is sufficient for...
The influence of vertical deflection of the supports in modeling squeeze film damping in torsional micromirrors
, Article Microelectronics Journal ; Volume 43, Issue 8 , 2012 , Pages 530-536 ; 00262692 (ISSN) ; Taghi Ahmadian, M ; Sharif University of Technology
Elsevier
2012
Abstract
The objective of this work is to create an analytical framework to study the problem of squeezed film damping in micromirrors considering the bending of the supporting torsion microbeams. Using mathematical and physical justifications, nonlinear Reynolds equation governing the behavior of the squeezed gas underneath the mirror is linearized. The resulting linearized equation is then nondimensionalized and analytically solved for two cases of the infinitesimal and finite tilting angle of the mirror. The obtained pressure distribution from the solution of the Reynolds equation is then utilized for finding the squeezed film damping force and torque applied to the mirror. The results show that...
Analytical modeling of squeeze film damping in micromirrors
, Article Proceedings of the ASME Design Engineering Technical Conference, 28 August 2011 through 31 August 2011, Washington, DC ; Volume 7 , 2011 , Pages 79-85 ; 9780791854846 (ISBN) ; Ahmadian, M. T ; Farshidianfar, A ; Sharif University of Technology
2011
Abstract
In the current paper, Extended Kantorovich Method (EKM) has been utilized to analytically solve the problem of squeezed film damping in micromirrors. A one term Galerkin approximation is used and following the extended Kantorovich procedure, the solution of the Reynolds equation which governs the squeezed film damping in micromirrors is reduced to solution of two uncoupled ordinary differential equation which can be solved iteratively with a rapid convergence for finding the pressure distribution underneath the micromirror. It is shown that the EKM results are independent of the initial guess function. It is also shown that since EKM is highly convergent, practically one iterate is...
Nonlinear Analysis of an Electrostatically Actuated Microbeam Considering Coupled Vibrations Due to Rotation
, Ph.D. Dissertation Sharif University of Technology ; Ahmadian, Mohammad Taghi (Supervisor) ; Firoozbakhsh, Keikhosrow (Supervisor)
Abstract
This research is concerned with the study of the static, dynamic, vibration and instability of an electrostatically actuated microbeam gyroscope considering geometric nonlinearities and electrostatic fringing fields. A vibrating microbeam gyroscope consists of a beam with a rigid (proof) mass attached to it and undergoes coupled flexural-flexural vibrations coupled with base rotation. The primary oscillation is generated in drive direction of the microbeam gyroscope by a pair of DC and AC voltages on the mass. The secondary oscillation occurring in the sense direction is induced by the Coriolis coupling caused by the input angular rate of the beam along its axis. In this case gyroscope acts...
Contact time study of electrostatically actuated microsystems
, Article Scientia Iranica ; Volume 17, Issue 5 B , SEPTEMBER-OCTOBER , 2010 , Pages 348-357 ; 10263098 (ISSN) ; Rashidian, B ; Ahmadian, M. T ; Sharif University of Technology
2010
Abstract
This paper presents a model to analyze contact phenomenon in microsystems actuated by ramp voltages, which has applications in frequency sweeping. First-order shear deformation theory is used to model dynamical system using finite element method, while finite difference method is applied to model squeeze film damping. The model is validated by static pull-in results. The presented hybrid FEMFDM model is utilized to compute values of contact time and dynamic behavior. Considering this model, effects of different geometrical and mechanical parameters on contact time are studied. The influence of imposing the additional reverse voltage on dynamic characteristics of the system is also...
Contact time study of microsystems actuated by ramp-input voltages
, Article ASME 2009 International Mechanical Engineering Congress and Exposition, IMECE2009, Lake Buena Vista, FL, 13 November 2009 through 19 November 2009 ; Volume 12, Issue PART A , 2010 , Pages 105-112 ; 9780791843857 (ISBN) ; Rashidian, B ; Ahmadian, M. T ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2010
Abstract
This paper presents a model to analyze contact phenomenon in microsystems, actuated by ramp voltages, which has applications in frequency sweeping. First-order shear deformation theory is used to model dynamical system using finite element method, while finite difference method is applied to model squeeze film damping. The model is validated by static pull-in results. The presented hybrid FEM-FDM model is utilized to compute values of contact time and dynamic behavior. Considering this model, effects of different geometrical and mechanical parameters on contact time are studied. The influence of imposing the additional reverse voltage on dynamic characteristics of the system is also...
Dynamic analysis of electrically actuated rectangular microplates with nonlinear plate theory under squeeze-film damping effect
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 13, Issue PART A , 2009 , Pages 401-408 ; 9780791848746 (ISBN) ; Moghimi Zand, M ; Ahmadian, M. T ; Sharif University of Technology
2009
Abstract
In this paper, dynamic behavior and pull-in phenomenon of electrically actuated rectangular micro plates under the effect of squeeze-film damping and nonlinear electrostatic force is studied. Finite element method is implemented in order to drive weak formulations of linear and nonlinear micro plate equations of motion based on classical plate theory (CPT) (for thin microplates with moderate nonlinearity) and squeeze-film damping based on Reynolds nonlinear equation. Finally, an efficient reduced-order model contingent on singular value decomposition method (SVD) is used to study dynamic pull-in phenomenon. This model is constructed by the global basis functions achieved from a few runs of...
Application of piezoelectric and functionally graded materials in designing electrostatically actuated micro switches
, Article Proceedings of the ASME Design Engineering Technical Conference, 15 August 2010 through 18 August 2010 ; Volume 4 , August , 2010 , Pages 613-620 ; 9780791844120 (ISBN) ; Ahmadian, M. T ; Design Engineering Division and Computers in Engineering Division ; Sharif University of Technology
2010
Abstract
In this research, a functionally graded microbeam bonded with piezoelectric layers is analyzed under electric force. Static and dynamic instability due to the electric actuation is studied because of its importance in micro electro mechanical systems, especially in micro switches. In order to prevent pull-in instability, two piezoelectric layers are used as sensor and actuator. A current amplifier is used to supply input voltage of the actuator from the output of the sensor layer. Using Hamilton's principle and Euler-Bernoulli theory, equation of motion of the system is obtained. It is shown that the load type (distributed or concentrated) applied to the microbeam from the piezoelectric...