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microelectromechanical-devices
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Effect of squeeze-film damping on the dynamic behavior of circular and rectangular microplates
, Article 2007 International Semiconductor Device Research Symposium, ISDRS, College Park, MD, 12 December 2007 through 14 December 2007 ; January , 2007 ; 1424418917 (ISBN); 9781424418916 (ISBN) ; Ahmadian, M. T ; Sadeghian, H ; Sharif University of Technology
2007
Influence of van der Waals force on the pull-in parameters of cantilever type nanoscale electrostatic actuators
, Article Microsystem Technologies ; Volume 12, Issue 12 , 2006 , Pages 1153-1161 ; 09467076 (ISSN) ; Alasty, A ; Akbari, J ; Sharif University of Technology
2006
Abstract
In this paper, the influence of the van der Waals force on two main parameters describing an instability point of cantilever type nanomechanical switches, which are the pull-in voltage and deflection are investigated by using a distributed parameter model. The fringing field effect is also taken into account. The nonlinear differential equation of the model is transformed into the integral form by using the Green's function of the cantilever beam. The integral equation is solved analytically by assuming an appropriate shape function for the beam deflection. The detachment length and the minimum initial gap of the cantilever type switches are given, which are the basic design parameters for...
Nonlinear dynamics of electrostatically actuated micro-resonator: Analytical solution by homotopy perturbation method
, Article IEEE/ASME International Conference on Advanced Intelligent Mechatronics, AIM ; July , 2014 , p. 1284-1289 ; Yazdi, M. H ; Pishkenari, H. N ; Miandoab, E. M ; Sharif University of Technology
Abstract
Dynamic behavior of a electrostatically actuated MEMS resonator is investigated. A double clamped micro-beam under distributed DC and AC actuation is used. Corresponding single degree of freedom model is derived using Galerkin's decomposition method. Homotopy Perturbation Method (HPM) is implemented in order to derive analytical expression for frequency response of the micro-resonator. Comparison of the obtained results with the numerical simulations confirms that HPM agrees very well with numerical simulations for a wide range of parameters. Obtained analytical solution can be used for design and optimization of MEMS resonators
Coupled electromechanical analysis of MEMS-based energy harvesters integrated with nonlinear power extraction circuits
, Article Microsystem Technologies ; 2016 , Pages 1-18 ; 09467076 (ISSN) ; Ahmadian, M. T ; Zohoor, H ; Sharif University of Technology
Springer Verlag
2016
Abstract
Application of piezoelectric materials in vibration energy harvesters is expanding rapidly, especially in MEMS-based devices, due to their uncomplicated fabrication processes and reasonable power generation potential. In addition to standard power extraction methods, nonlinear switched techniques with capability of generated power enhancement, are previously developed and extensively applied in energy harvesting using piezoelectric materials. In this article, vibratory behavior of bimorph resonant harvesters coupled to nonlinear circuits of energy harvesting including standard and switched techniques is investigated. An analytical approach employing some perturbation technique, is utilized...
Nonlinear dynamics of MEMS/NEMS resonators: analytical solution by the homotopy analysis method
, Article Microsystem Technologies ; 2016 , Pages 1-14 ; 09467076 (ISSN) ; Hairi Yazdi, M. R ; Nejat Pishkenari, H ; Sharif University of Technology
Springer Verlag
2016
Abstract
Due to various sources of nonlinearities, micro/nano-electro-mechanical-system (MEMS/NEMS) resonators present highly nonlinear behaviors including softening- or hardening-type frequency responses, bistability, chaos, etc. The general Duffing equation with quadratic and cubic nonlinearities serves as a characterizing model for a wide class of MEMS/NEMS resonators as well as lots of other engineering and physical systems. In this paper, after brief reviewing of various sources of nonlinearities in micro/nano-resonators and discussing how they contribute to the Duffing-type nonlinearities, we propose a Homotopy Analysis Method (HAM) approach for derivation of analytical solutions for the...
On the energy extraction from large amplitude vibrations of MEMS-based piezoelectric harvesters
, Article Acta Mechanica ; Volume 228, Issue 10 , 2017 , Pages 3445-3468 ; 00015970 (ISSN) ; Ahmadian, M. T ; Zohoor, H ; Sharif University of Technology
Abstract
As sizes decrease, the advantages of application of piezoelectric materials for mechanical to electrical energy conversion become more obvious in comparison with electromagnetic and electrostatic techniques, according to uncomplicated fabrication processes of microscale piezoelectric harvesters together with their considerable amounts of generated power. Cantilevered silicon beams with surface bounded piezoelectric layers form the main structure of these MEMS-based harvesters. Lowering the resonance frequency down to the range of environmental vibration frequencies is one of the most significant challenges in MEMS harvesters which is usually attempted to be achieved by thinning the beam and...
Coupled electromechanical analysis of MEMS-based energy harvesters integrated with nonlinear power extraction circuits
, Article Microsystem Technologies ; Volume 23, Issue 7 , 2017 , Pages 2403-2420 ; 09467076 (ISSN) ; Ahmadian, M. T ; Zohoor, H ; Sharif University of Technology
Springer Verlag
2017
Abstract
Application of piezoelectric materials in vibration energy harvesters is expanding rapidly, especially in MEMS-based devices, due to their uncomplicated fabrication processes and reasonable power generation potential. In addition to standard power extraction methods, nonlinear switched techniques with capability of generated power enhancement, are previously developed and extensively applied in energy harvesting using piezoelectric materials. In this article, vibratory behavior of bimorph resonant harvesters coupled to nonlinear circuits of energy harvesting including standard and switched techniques is investigated. An analytical approach employing some perturbation technique, is utilized...
Nonlinear dynamics of MEMS/NEMS resonators: analytical solution by the homotopy analysis method
, Article Microsystem Technologies ; Volume 23, Issue 6 , 2017 , Pages 1913-1926 ; 09467076 (ISSN) ; Hariri Yazdi, M. R ; Nejat Pishkenari, H ; Sharif University of Technology
Springer Verlag
2017
Abstract
Due to various sources of nonlinearities, micro/nano-electro-mechanical-system (MEMS/NEMS) resonators present highly nonlinear behaviors including softening- or hardening-type frequency responses, bistability, chaos, etc. The general Duffing equation with quadratic and cubic nonlinearities serves as a characterizing model for a wide class of MEMS/NEMS resonators as well as lots of other engineering and physical systems. In this paper, after brief reviewing of various sources of nonlinearities in micro/nano-resonators and discussing how they contribute to the Duffing-type nonlinearities, we propose a Homotopy Analysis Method (HAM) approach for derivation of analytical solutions for the...
Optimization of a serpentine model for low-dispersion flows in micro channel turns
, Article 5th International Conference on Perspective Technologies and Methods in MEMS Design, MEMSTECH 2009, Lviv-Polyana, 22 April 2009 through 24 April 2009 ; 2009 , Pages 136-140 ; 9789662191066 (ISBN) ; Afsharikia, S ; Taghizadeh Manzari, M.T ; Sharif University of Technology
2009
Abstract
Chip-based micro fluidic separation systems often use serpentine channels to attain long separation lengths in a compact area. Such designs suffer from the dispersion, mostly 'racetrack' effect, due to the bends in the micro channels. The main goal of this paper is obtaining a model which has minimal racetrack in a serpentine geometry. A numerical analysis leads us to an optimized model which is different from previous attempts in this field. Our model uses modified turn radii, optimal length between bends with a constant zeta-potential boundary condition and a constant width through micro channel turns. It is shown that traveling fluid in this geometry has minimal dispersion as well as...
Application of homotopy analysis method in studying dynamic pull-in instability of microsystems
, Article Mechanics Research Communications ; Volume 36, Issue 7 , 2009 , Pages 851-858 ; 00936413 (ISSN) ; Ahmadian, M. T ; Sharif University of Technology
2009
Abstract
In this study, homotopy analysis method is used to derive analytic solutions to predict dynamic pull-in instability of electrostatically-actuated microsystems. The model considers midplane stretching, initial stress, distributed electrostatic force and fringing fields effect. Influences of different parameters on dynamic pull-in instability are investigated. Results are in good agreement with numerical and experimental findings. © 2009 Elsevier Ltd. All rights reserved
Corotational nonlinear finite element formulation and modeling of electrostatically actuated microbeams
, Article JVC/Journal of Vibration and Control ; Volume 15, Issue 4 , 2009 , Pages 617-640 ; 10775463 (ISSN) ; Borhan, H ; Esmailzadeh, E ; Sharif University of Technology
2009
Abstract
A complete nonlinear finite element model for coupled-domain microelectromechanical system devices with electrostatic actuation and squeeze film effect was developed. for this purpose, a corotational finite element formulation for the dynamic analysis of planer Euler-Bernoulli microbeams considering geometrical nonlinearities due to both large structural deformation and electrostatic actuation is developed. In this method, the internal forces due to deformation and residual stresses, the elemental inertias, and the damping effect of the squeeze-film are systematically derived by consistent linearization of the fully geometrically nonlinear beam theory using d'Alembert and the virtual work...
Nonlinear dynamics of nano-resonators: an analytical approach
, Article Microsystem Technologies ; 2015 ; 09467076 (ISSN) ; Nejat Pishkenari,, H ; Yousefi Koma, A ; Sharif University of Technology
Abstract
Prior to the design and fabrication of MEMS/NEMS devices, analysis of static and dynamic behaviors of these systems is necessary. In the present study, the nonlinear dynamic behavior of micro- and nano-mechanical resonators is investigated and classified based on the resonator’s physical parameters for first time. The Galerkin method is used to convert the distributed-parameter model to a nonlinear ordinary differential equation where mid-plane stretching, axial stress, DC electrostatic and AC harmonic voltages are taken into account. To obtain the analytical frequency response of the micro resonator near its primary resonance, the second order multiple scales method is applied to the...
Classification of the nonlinear dynamics in an initially curved bistable micro/nanoelectro-mechanical system resonator
, Article Micro and Nano Letters ; Volume 10, Issue 10 , Oct , 2015 , Pages 583-588 ; 17500443 (ISSN) ; Hairi Yazdi, M. R ; Nejat Pishkenari, H ; Maani Miandoab, E ; Ouakad, H.M ; Sharif University of Technology
Institution of Engineering and Technology
2015
Abstract
The nonlinear dynamics of a bistable micro/nano-electro-mechanical system resonator composed of an arch-shaped microbeam is investigated. The initially curved microbeam is actuated through a combined DC and AC electrostatic parallel plate field. A single degree of freedom model obtained using the Galerkin's decomposition method with distributed electrostatic force is implemented in order to investigate the resonator dynamics near its primary resonance. According to the shape of the potential energy function which depends on the system parameters, the nonlinear dynamics of the system are classified into certain categories. The appearance of various nonlinear phenomena including dynamic...
Static pull-in analysis of electrostatically actuated microbeams using homotopy perturbation method
, Article Applied Mathematical Modelling ; Volume 34, Issue 4 , 2010 , Pages 1032-1041 ; 0307904X (ISSN) ; Moghimi Zand, M ; Ahmadian, M. T ; Sharif University of Technology
Abstract
In this study, static pull-in instability of electrostatically-actuated microbridges and microcantilevers is investigated considering different nonlinear effects. Galerkin's decomposition method is utilized to convert the nonlinear differential equations of motion to nonlinear integro-algebraic equations. Afterward, analytic solutions to static deflections of the microbeams are obtained using the homotopy perturbation method. Results are in excellent agreement with those presented in the literature
Dynamic pull-in instability of electrostatically actuated beams incorporating Casimir and van der Waals forces
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 224, Issue 9 , 2010 , Pages 2037-2047 ; 09544062 (ISSN) ; Ahmadian, M.T ; Sharif University of Technology
2010
Abstract
In this study, influences of intermolecular forces on the dynamic pull-in instability of electrostatically actuated beams are investigated. The effects of midplane stretching, electrostatic actuation, fringing fields, and intermolecular forces are considered. The boundary conditions of the beams are clamped-free and clamped-clamped. A finite-element model is developed to discretize the governing equations, and Newmark time discretization is then employed to solve the discretized equations. The static pull-in instability is investigated to validate the model. Finally, dynamic pull-in instability of cantilevers and double-clamped beams are studied considering the Casimir and van der Waals...
Nonlinear dynamics of nano-resonators: an analytical approach
, Article Microsystem Technologies ; Volume 22, Issue 9 , 2016 , Pages 2259-2271 ; 09467076 (ISSN) ; Nejat Pishkenari, H ; Yousefi Koma, A ; Sharif University of Technology
Springer Verlag
Abstract
Prior to the design and fabrication of MEMS/NEMS devices, analysis of static and dynamic behaviors of these systems is necessary. In the present study, the nonlinear dynamic behavior of micro- and nano-mechanical resonators is investigated and classified based on the resonator’s physical parameters for first time. The Galerkin method is used to convert the distributed-parameter model to a nonlinear ordinary differential equation where mid-plane stretching, axial stress, DC electrostatic and AC harmonic voltages are taken into account. To obtain the analytical frequency response of the micro resonator near its primary resonance, the second order multiple scales method is applied to the...
Characterization of a nonlinear MEMS-based piezoelectric resonator for wideband micro power generation
, Article Applied Mathematical Modelling ; Volume 41 , 2017 , Pages 121-142 ; 0307904X (ISSN) ; Ahmadian, M. T ; Sharif University of Technology
Elsevier Inc
2017
Abstract
Micro-scale piezoelectric unimorph beams with attached proof masses are the most prevalent structures in MEMS-based energy harvesters considering micro fabrication and natural frequency limitations. In doubly clamped beams a nonlinear stiffness is observed as a result of midplane stretching effect which leads to amplitude-stiffened Duffing resonance. In this study, a nonlinear model of a doubly clamped piezoelectric micro power generator, taking into account geometric nonlinearities including stretching and large curvatures, is investigated. The governing nonlinear coupled electromechanical partial differential equations of motion are determined by exploiting Hamilton's principle. A...
Recent advancements in bulk metallic glasses and their applications: A review
, Article Critical Reviews in Solid State and Materials Sciences ; Volume 43, Issue 3 , 2018 , Pages 233-268 ; 10408436 (ISSN) ; Nemati, A ; Rahman, Z.U ; Shah, U. H ; Asgar, H ; Haider, W ; Sharif University of Technology
Taylor and Francis Inc
2018
Abstract
Bulk metallic glasses (BMGs), that display extraordinary properties of high strength, corrosion resistance, polymer-like formability, and excellent magnetic properties, are emerging as modern quintessential engineering materials. BMGs have garnered significant research enthusiasm owing to their tremendous technological and scientific standing. In this article, the recent advancements in the field of BMGs and their applications are put in a nutshell. Novel state-of-the-art production routes and nano/microimprinting strategies with salient features capable of circumventing the processing related complexities as well as accelerating modern developments, are briefly summarized. Heterogeneous BMG...
A combined experimental and numerical study of the effect of surface roughness on nanoindentation
, Article International Journal of Applied Mechanics ; Volume 11, Issue 7 , 2019 ; 17588251 (ISSN) ; Chamani, M ; Baghani, M ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd
2019
Abstract
Gold and copper thin films are widely used in microelectromechanical system (MEMS) and nanoelectromechanical system (NEMS) devices. Nanoindentation has been developed in mechanical characterization of thin films in recent years. Several researchers have examined the effect of surface roughness on nanoindentation results. It is proved that the surface roughness has great importance in nanoindentation of thin films. In this paper, the surface topography of thin films is simulated using the extracted data from the atomic force microscopy (AFM) images. Nanoindentation on a rough surface is simulated using a three-dimensional finite-element model. The results are compared with the results of...
Micro resonator nonlinear dynamics considering intrinsic properties
, Article Scientia Iranica ; Volume 16, Issue 2 B , 2009 , Pages 121-129 ; 10263098 (ISSN) ; Tadayon, M. A ; Eftekharian, A. A ; Sharif University of Technology
2009
Abstract
One of the most important phenomena to affect the motion behaviour of Micro Resonators is their thermal dependency. This has recently received the attention of researchers widely. A thermal phenomenon has two main effects, the first is damping, due to internal friction, and the second is softening, due to Young's modulus-temperature relationship. In this research work, some theoretical and experimental reported results are used to make a proper model, including thermal phenomena. Two Lorentzian functions are used to describe the restoring and damping forces caused by thermal phenomena. In order to emphasize the thermal effects, a nonlinear model of the MEMS, considering capacitor...