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    Design, modeling and optimization of a novel two DOF polymeric electro-thermal micro-actuator

    , Article Applied Mechanics and Materials ; Vol. 307 , 2013 , pp. 112-116 ; ISSN: 16609336 ; ISBN: 9783037856598 Sheikhbahaie, R ; Alasty, A ; Salarieh, H ; Sharif University of Technology
    Abstract
    In this paper, design, simulation and optimization of a novel electrothermally-activated polymeric microactuator capable of generating combination of bidirectional lateral and rotational motions are presented. The composite structure of this actuator is consisted of a symmetric meandered shape silicon skeleton, a SU8 thermal expandable polymer and a thin film chrome layer heater. This actuator is controlled by applying appropriate voltages on its four terminals. With the purpose of dimension optimization, a numerical parametric study is executed. The modeled actuator which is 1560 ?m long, 156 ?m wide and 30 ?m thick, demonstrates a remarkable lateral displacement of 23 ?m at power... 

    Design and analysis of a novel two DOF thermal micromanipulator

    , Article 2011 IEEE International Conference on Mechatronics, ICM 2011 - Proceedings ; 2011 , pp. 654-659 ; ISBN: 9781612849836 Pourzand, H ; Ghaemi, R ; Alasty, A ; Sharif University of Technology
    Abstract
    In this paper, a novel thermal microactuator is designed which is capable of producing bi-directional lateral and rotational output and one of its applications as a two DOF micromanipulator is shown. Also, by carefully choosing the doping level, temperature distribution is determined by considering the dependency of silicon's resistivity and conductivity to temperature. Using variable separation method an equation in terms of elliptic integrals is reached and after imposing boundary conditions the exact temperature distribution is obtained numerically. Currents at each branch is updated due to the last temperature distribution and this process is repeated several times until the final... 

    Fabrication of a novel six DOF thermal nanopositioner by using bulk micromachining process

    , Article IEEE International Conference on Mechatronics, ICM 2011 - Proceedings ; 2011 , pp. 702-707 ; ISBN: 9781612849836 Ghaemi, R ; Pourzand, H ; Alasty, A ; Akrami, S .M. R ; Sharif University of Technology
    Abstract
    In this paper, a novel microfabrication process of a six DOF thermal compliant nanopositioner is presented. The microfabrication process was based on bulk micromachining process. By using this process some important operational restrictions which are usually created by surface micromachining were removed. Moreover, this novel process does not need SOI wafers and needs only ordinary wafers. Therefore, it makes microfabrication process cheaper than surface micromachining processes where SOI wafer should be used. This method is completely appropriate for microactuators which have 120 degree misalignment. Finally, a primary test by using interferometer method was used to test connection of... 

    Fabrication of a novel six DOF thermal nanopositioner by using bulk micromachining process

    , Article 2011 IEEE International Conference on Mechatronics, ICM 2011 - Proceedings, 13 April 2011 through 15 April 2011 ; April , 2011 , Pages 702-707 ; 9781612849836 (ISBN) Ghaemi, R ; Pourzand, H ; Alasty, A ; Akrami, S. M. R ; Sharif University of Technology
    Abstract
    In this paper, a novel microfabrication process of a six DOF thermal compliant nanopositioner is presented. The microfabrication process was based on bulk micromachining process. By using this process some important operational restrictions which are usually created by surface micromachining were removed. Moreover, this novel process does not need SOI wafers and needs only ordinary wafers. Therefore, it makes microfabrication process cheaper than surface micromachining processes where SOI wafer should be used. This method is completely appropriate for microactuators which have 120 degree misalignment. Finally, a primary test by using interferometer method was used to test connection of... 

    Physical-Phenomenological Constitutive Modeling and Numerical Analysis of Magnetic Shape Memory Alloys

    , M.Sc. Thesis Sharif University of Technology Mousavi, Mohammad Reza (Author) ; Arghavani, Jamal (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Naghdabadi, Reza (Co-Advisor)
    Abstract
    Magnetic shape memory alloys (MSMAs) are a new class of smart materials that exhibit characteristics of large recoverable strains and high frequency. These unique characteristics, make MSMAs interesting materials for applications such as actuators, sensors, and energy harvesters. This thesis presents a three-dimensional phenomenological constitutive model for MSMAs, developed within the framework of irreversible continuum thermodynamics. To this end, a proper set of internal variables is introduced to reflect the microstructural consequences on the material macroscopic behavior. Moreover, a stress-dependent thermodynamic force threshold needed for variant reorientation is introduced which... 

    Design, Fabrication and Control of a novel Polymeric Thermal Microactuator

    , M.Sc. Thesis Sharif University of Technology Sheikhbahaie, Reza (Author) ; Alasty, Aria (Supervisor) ; Salarieh, Hassan (Supervisor)
    Abstract
    Systems composed of electrical and mechanical elements in micrometer scale are called microelectromechanical systems which are commonly fabricated on silicon substrates. These systems are in connection with environment by the means of sensors and actuators. Thermal microactuators as one of the most applicable actuators produce force and displacement on the basis of thermal expansion.Recently, by the advent of some polymers compatible with microfabrication methods such as SU8 and due to their remarkable thermal properties,polymeric thermal microactuators are attracting more attention in a way that polymeric type of almost every predesigned thermal microactuators are fabricated and much... 

    An analytical approach to modeling static behavior of torsional nano-/micro-actuators under effect of van der Waals force

    , Article Japanese Journal of Applied Physics ; Volume 51, Issue 3 PART 1 , 2012 ; 00214922 (ISSN) Moeenfard, H ; Darvishian, A ; Ahmaidan, M. T ; Zohoor, H ; Sharif University of Technology
    Abstract
    In this research, the static behavior of torsional nano-/micro-actuators under van der Waals (vdW) force is studied. First, the equilibrium equation governing the static behavior of torsional nano-/micro-actuators under vdW force is obtained. Then the energy method is utilized to investigate the statical stability of nano-/micro-actuator equilibrium points and a useful equation is suggested for the successful and stable design of nano-/micro-actuators under vdW force. Then, the equilibrium angle of nano-/micro-actuators is calculated both numerically and analytically using the homotopy perturbation method (HPM). It is observed that, with increasing instability number, defined in this paper,... 

    Modeling and analytical solution of hybrid thermopiezoelectric micro actuator and performance study under changing of different parameters

    , Article Mechanics of Advanced Materials and Structures ; Volume 22, Issue 10 , Mar , 2015 , Pages 785-793 ; 15376494 (ISSN) Pourrostami, H ; Kargarnovin, M. H ; Zohoor, H ; Sharif University of Technology
    Taylor and Francis Inc  2015
    Abstract
    Micro actuators are an irreplaceable part of motion control in miniaturized systems and are intended to have a high range of deformation, high accuracy, large force, and quick response. In this article, an analytical model for a hybrid thermopiezoelectric micro actuator is developed in which a double lead-zirconnate-titanate piezoceramic (PZT) beam structure consisting of two arms with different lengths are used. Governing differential equation of motion and electrical field are derived and solved. Out of parametric studies it was observed that, under application of temperature and voltage gradients, the deflection of the actuator shows different trends depending on the geometry of the micro... 

    Multi-objective optimization of piezoelectric microactuator using genetic algorithms

    , Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 13, Issue PART B , 2009 , Pages 723-730 ; 9780791848746 (ISBN) Esteki, H ; Hasannia, A ; Sharif University of Technology
    2009
    Abstract
    In flex-tensional piezoactuators, due to the low displacement of piezostacks, a compliant mechanism is used to amplify displacement of piezostack. In this paper, optimization of a compliant mechanism with corner-filleted flexure hinges is carried out using real-coded genetic algorithms (GAs) to avoid trapping in local optimums. The objective functions are displacement amplification and stiffness of mechanism and design variables are cross-sectional size and material used. The constraints which are applied on mechanism are based on piezostack dimensions and manufacturing limits. Displacement amplification and stiffness are calculated using strain energy and Castigliano's displacement theorem.... 

    Closed-form solutions of the pull-in instability in nano-cantilevers under electrostatic and intermolecular surface forces

    , Article International Journal of Solids and Structures ; Volume 44, Issue 14-15 , 2007 , Pages 4925-4941 ; 00207683 (ISSN) Ramezani, A ; Alasty, A ; Akbari, J ; Sharif University of Technology
    2007
    Abstract
    In this paper, a distributed parameter model is used to study the pull-in instability of cantilever type nanomechanical switches subjected to intermolecular and electrostatic forces. In modeling of the electrostatic force, the fringing field effect is taken into account. The model is nonlinear due to the inherent nonlinearity of the intermolecular and electrostatic forces. The nonlinear differential equation of the model is transformed into the integral form by using the Green's function of the cantilever beam. Closed-form solutions are obtained by assuming an appropriate shape function for the beam deflection to evaluate the integrals. The pull-in parameters of the switch are computed under... 

    Robust shape control of two SMA actuators attached to a flexible beam based on DK iteration

    , Article International Conference on Control, Automation and Systems ; 2012 , Pages 316-321 ; 15987833 (ISSN) ; 9781467322478 (ISBN) Alambeigi, F ; Zamani, A ; Vossoughi, G ; Zakerzadeh, M. R ; Sharif University of Technology
    2012
    Abstract
    There has been great demand for shape memory alloy (SMA) wires as actuators for shape control of flexible structures. The experimental setup of this study consists of a flexible beam actuated by two active SMA actuators. The input applied to the SMA actuator in this setup is electrical current while the output is the strain or position. To control strain of the actuator, the SMA wire is heated resistively in order to reach the desired temperature calculated by inverse of the phenomenological model. In heating the SMA wire resistively, the controllable quantity is the heat input to the wire via an applied current. In controller design, changes of physical properties of SMA wires and the... 

    Nonlinear analysis of a flexible beam actuated by a couple of active SMA wire actuators

    , Article International Journal of Engineering, Transactions A: Basics ; Volume 25, Issue 3 , 2012 , Pages 249-264 ; 17281431 (ISSN) Sayyaadi, H ; Zakerzadeh, M. R ; Sharif University of Technology
    2012
    Abstract
    There are two different ways of using SMA wires as actuators for shape control of flexible structures; which can be either embedded within the composite laminate or externally attached to the structure. Since the actuator can be placed at different offset distances from the beam, external actuators produce more bending moment and, consequently, considerable shape changes with the same magnitude of the actuation force comparing to the embedded type. Such a configuration also provides fast convection which is very important in shape control applications that require a high-frequency response of SMA actuators. Although combination and modeling of externally-attached SMA actuator wires and... 

    Analysis of a flexible beam actuated by two active SMA wires

    , Article ASME 2010 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2010, 28 September 2010 through 1 October 2010 ; Volume 1 , October , 2010 , Pages 661-672 ; 9780791844151 (ISBN) Zakerzadeh, M. R ; Sayyaadi, H ; Aerospace Division ; Sharif University of Technology
    2010
    Abstract
    There are two ways of using SMAs as actuators for shape control of flexible structures; they can be either embedded within composite laminates or externally attached to the structures. Since the actuator can be placed at different offset distances from the beam, external actuators produce more bending moment and, consequently, more shape change. Such a configuration also allows introduction of fast convection cooling, very important in shape control applications that require a high-frequency response of SMA actuators. Although combination and modeling of externally-attached SMA actuator wires and strips have been widely considered by some researchers, these studies have some weaknesses that... 

    Optimum design and vibration suppression of a piezoelectric amplified microactuator using FEM analysis

    , Article s20th International Microprocesses and Nanotechnology Conference, MNC 2007, Kyoto, 5 November 2007 through 8 November 2007 ; February , 2007 , Pages 378-379 ; 4990247248 (ISBN); 9784990247249 (ISBN) Mahboobi, H ; Shahidi, A ; Pirouzpanah, S ; Esteki, H ; Sarkar, S ; Sharif University of Technology
    2007
    Abstract
    In this research the optimum design of a piezoelectric amplified microactuator has been achieved via equation (1) and sensitivity analysis in FEM simulation software. In addition, for the sake of simplicity and utilizing the FEM software simulation facilities, the control strategy has been embedded in FEM simulation as a programming routine. The simulations showed the efficiency of the proposed controller to suppress the microactuator's undesired vibrations  

    Position control of shape memory alloy actuator based on the generalized Prandtl-Ishlinskii inverse model

    , Article Mechatronics ; Volume 22, Issue 7 , 2012 , Pages 945-957 ; 09574158 (ISSN) Sayyaadi, H ; Zakerzadeh, M. R ; Sharif University of Technology
    2012
    Abstract
    Hysteresis and significant nonlinearities in the behavior of Shape Memory Alloy (SMA) actuators encumber effective utilization of these actuator. Due to these effects, the position control of SMA actuators has been a great challenge in recent years. Literature review of the research conducted in this area shows that using the inverse of the phenomenological hysteresis models can compensate the hysteresis of these actuators effectively. But, inverting some of these models, such as Preisach model, is numerically a complex task. However, the generalized Prandtl-Ishlinskii model is analytically invertible, and therefore can be implemented conveniently as a feedforward controller for compensating... 

    Modeling of a nonlinear Euler-Bernoulli flexible beam actuated by two active shape memory alloy actuators

    , Article Journal of Intelligent Material Systems and Structures ; Volume 22, Issue 11 , 2011 , Pages 1249-1268 ; 1045389X (ISSN) Zakerzadeh, M. R ; Salehi, H ; Sayyaadi, H ; Sharif University of Technology
    2011
    Abstract
    There are two different ways of using shape memory alloy (SMA) wire as an actuator for shape control of flexible structures: it can be either embedded within the composite laminate or externally attached to the structure. As the actuator can be placed at different offset distances from the beam, external actuators produce more bending moment and, consequently, considerabnle shape changes with the same magnitude of actuation force compared with the embedded type. Such a configuration also provides faster heat transfer rate owing to convection, which is very important in shape control applications that require a highfrequency response of SMA actuators. Although combination and physics-based...