Search for: vibration-control
0.009 seconds
Total 94 records

    Self-powered hybrid electromagnetic damper for cable vibration mitigation

    , Article Smart Structures and Systems ; Volume 20, Issue 3 , 2017 , Pages 285-301 ; 17381584 (ISSN) Jamshidi, M ; Chang, C ; Bakhshi, A ; Sharif University of Technology
    This paper presents the design and the application of a new self-powered hybrid electromagnetic damper that can harvest energy while mitigating the vibration of a structure. The damper is able to switch between an energy harvesting passive mode and a semi-active mode depending on the amount of energy harvested and stored in the battery. The energy harvested in the passive mode resulting from the suppression of vibration is employed to power up the monitoring and electronic components necessary for the semi-active control. This provides a hybrid control capability that is autonomous in terms of its power requirement. The proposed hybrid circuit design provides two possible options for the... 

    Optimal vibration control of rotors with an open edge crack using an electromagnetic actuator

    , Article JVC/Journal of Vibration and Control ; Volume 24, Issue 1 , 2018 , Pages 37-59 ; 10775463 (ISSN) Ebrahimi, A ; Heydari, M ; Behzad, M ; Sharif University of Technology
    SAGE Publications Inc  2018
    Vibration control, especially in cracked rotors, is an important factor that can prevent the occurrence of disastrous failures. In this paper, vibrational control of a cracked rotor with an electromagnetic actuator has been studied with a continuous model of flexural vibration of cracked rotors. The governing equation of motion for the rotor under the external excitation of the electromagnetic actuator, gravity, and unbalanced forces is presented. A control law for the optimal control method to minimize the vibration of the rotor or stress at the crack section was obtained. To this aim, two cost functions have been introduced, based on the overall vibration of the rotor and the maximum... 

    A new self-powered electromagnetic damper for structural vibration control

    , Article Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2017, 26 March 2017 through 29 March 2017 ; Volume 10168 , 2017 ; 0277786X (ISSN); 9781510608214 (ISBN) Jamshidi, M ; Chang, C. C ; Fiberguide Industries; Frontiers Media; OZ Optics, Ltd.; Polytec, Inc.; The Society of Photo-Optical Instrumentation Engineers (SPIE) ; Sharif University of Technology
    SPIE  2017
    This paper presents a new self-powered hybrid electromagnetic damper that can mitigate vibration of a structure. The damper is able to switch between a power-regenerative passive mode and a semi-active mode depending on the power demand and capacity. The energy harvested in the passive mode due to suppression of vibration is employed to power up the sensing and electronic components necessary for the semi-active control. This provides a hybrid control capability that is autonomous in terms of its power requirement. The device mechanism and the circuitry that can realize this self-powered electromagnetic damper are described in this paper. The parameters that determine the device feasible... 

    Vibration isolation of a ship's seat

    , Article Smart Structures and Materials 2005 - Damping and Isolation, San Diego, CA, 7 March 2005 through 10 March 2005 ; Volume 5760 , 2005 , Pages 607-617 ; 0277786X (ISSN) Agahi, M ; Bahrami Samani, M ; Behzad, M ; Sharif University of Technology
    Different factors cause vibration. These vibrations make the voyages difficult and reduce comfort and convenience in passenger ships. In this paper, the creating factors of vibration have discussed first, then with mathematical modelling it will be attempted to minimize the vibration over the crew's seat. The modelling consists of a system with two degrees of freedom and by using vibration visolation with passive method of Tuned Mass Damper (TMD) it will be tried to reduce the vibration over personnel. Moreover using active control systems will be compared with passive systems  

    Exact boundary controllability of vibrating non-classical Euler-Bernoulli micro-scale beams

    , Article Journal of Mathematical Analysis and Applications ; Vol. 418, issue. 2 , 2014 , pp. 985-997 ; ISSN: 0022247X Vatankhah, R ; Najafi, A ; Salarieh, H ; Alasty, A ; Sharif University of Technology
    This study investigates the exact controllability problem for a vibrating non-classical Euler-Bernoulli micro-beam whose governing partial differential equation (PDE) of motion is derived based on the non-classical continuum mechanics. In this paper, it is proved that via boundary controls, it is possible to obtain exact controllability which consists of driving the vibrating system to rest in finite time. This control objective is achieved based on the PDE model of the system which causes that spillover instabilities do not occur  

    Analysis of fuselage vibration during flapping flights and solution for reduce it

    , Article 44th AIAA Aerospace Sciences Meeting 2006, Reno, NV, 9 January 2006 through 12 January 2006 ; Volume 11 , 2006 , Pages 7681-7687 ; 1563478072 (ISBN); 9781563478079 (ISBN) Vahdat, D ; Sharif University of Technology
    This article presents the result of an analysis to determine the distance that the fuselage of a Flapping Flyer moves up and down when the wing flap and comparison it with experiments that was done on fuselage phenomena during flight of an ornithopters and Winged animals in Wind tunnel. It is suggested that this motion may reduce the efficiency of design, whereas the tendency for fuselage motion may be largely cancelled in the bi plane configuration. The article also answers a question that has puzzled for scientist. Why bodies of winged animals don't move up and down noticeably when they flaps their wing during flight? Finally we offer one solution for reduce this unwanted motion near 50 %... 

    Nonlinear free vibrations of a Timoshenko beam using multiple scales method

    , Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 2 , 2004 , Pages 101-106 ; 0791841731 (ISBN); 9780791841730 (ISBN) Ramezani, A ; Ghorashi, M ; Sharif University of Technology
    American Society of Mechanical Engineers  2004
    In this paper, the large amplitude free vibration of a cantilever Timoshenko beam is considered. To this end, first Hamilton's principle is used in deriving the partial differential equation of the beam response under the mentioned conditions. Then, implementing the Galerkin's method the partial differential equation is converted to an ordinary nonlinear differential equation. Finally, the method of multiple scales is used to determine a second order perturbation solution for the obtained ODE. The results show that nonlinearity acts in the direction of increasing the natural frequency of the thick-cantilevered beam  

    Boundary control design for vibration suppression and attitude control of flexible satellites with multi-section appendages

    , Article Acta Astronautica ; Volume 173 , 2020 , Pages 22-30 Ataei, M. M ; Salarieh, H ; Nejat Pishkenari, H ; Jalili, H ; Sharif University of Technology
    Elsevier Ltd  2020
    Attitude and vibration control of a general form of flexible satellites is addressed in this paper. Partial differential dynamic equations are derived considering new details such as multi sectioned solar panels and elastic connections between main hub and solar panels. Boundary control approach is adopted to eliminate simplification errors of discrete models, using just one actuator in the hub. Asymptotic stability of attitude dynamics is proved for a group of boundary controllers and necessary conditions for asymptotic stability of vibrations are discussed. Being independent of modeling accuracy and using easily measurable feedbacks are among advantages of the proposed class of... 

    Dynamic control of supported macro/micro-tubes conveying magnetic fluid utilizing intelligibly designed axially functionally graded materials

    , Article International Journal of Computer Integrated Manufacturing ; 2021 ; 0951192X (ISSN) Du, J ; Mirtalebi, S. H ; Ahmadian, M. T ; Cao, Y ; Suhatril, M ; Assilzadeh, H ; Sharif University of Technology
    Taylor and Francis Ltd  2021
    In this study, dynamic modeling of an elbow axially functionally graded (AFG) macro/micro-tube carrying magnetic flow with different cross-sections is considered. Parametric optimization is performed for vibration suppression of such fluid-interaction systems. Implementing computer simulations, passive vibration control procedures, along with the effect of AFG materials and magnetic properties of the fluid as well as precisely manufactured geometry of the system, is investigated. It is assumed that the material characteristics of the system vary in the longitudinal direction based on exponential and power-law distribution profiles. Influence of the downstream inclination angle and... 

    Attenuation of Random Vibration in Plate

    , M.Sc. Thesis Sharif University of Technology Jolghazi, Saeed (Author) ; Behzad, Mehdi (Supervisor) ; Mahdigholi, Hamid (Supervisor)
    This paper is a study on control of vibration of plate subjected to random vibration loading using magnetorheological (MR) dampers. Some key issues, i.e. model reduction, modeling of the MR dampers and their applications in vibration control of plates, are addressed in this work. MR dampers are semi-active devices that use MR fluids to produce a controllable damping with low power requirement. In this paper, first, a model reduction method for preparing a reduce order model (ROM) is presented. The method uses an optimal model truncation method which in it the ROM to be constructed such that it will provide the same frequency response characteristics as the original full model within the... 

    A continuous model for forced vibration analysis of a cracked beam

    , Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 74 DSC, Issue 2 PART B , 2005 , Pages 1849-1855 ; 0791842169 (ISBN); 9780791842164 (ISBN) Behzad, M ; Meghdari, A ; Ebrahimi, A ; Sharif University of Technology
    In this paper the equation of motion and corresponding boundary conditions has been developed for forced bending vibration analysis of a beam with an open edge crack. A uniform Euler-Bernoulli beam and the Hamilton principle have been used in this research. The natural frequencies and the forced response of this beam have been obtained using the new developed model in conjunction with the Galerkin projection method. The crack has been modeled as a continuous disturbance function in displacement filed which could be obtained from fracture mechanics. The results show that the first natural frequency will reduce when the crack depth ratio increases. Also the rate of this reduction depends on... 

    Fuzzy control of robot manipulator with a flexible tool

    , Article Journal of Robotic Systems ; Volume 22, Issue 7 , 2005 , Pages 367-382 ; 07412223 (ISSN) Alasty, A ; Sepehri, A ; Sharif University of Technology
    In some tasks, a rigid robot manipulator handles a long, slender, and flexible tool, which usually has not been equipped with vibration measuring devices. This situation makes a different tool tip position control problem. In this paper, a new method will be presented for simultaneous tip position and vibration suppression control of a flexible tool on a rigid-link 3-DOF robot. This approach uses fuzzy logic rule-based controllers without using any sensors and actuators on the tool or a priori knowledge about the tool. Numerical simulation of robot and tool set has been accomplished and results support the fact that designed fuzzy controllers perform remarkably well in reducing vibrations... 

    Reliability-based optimization of an active vibration controller using evolutionary algorithms

    , Article Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2017, 26 March 2017 through 29 March 2017 ; Volume 10168 , 2017 ; 0277786X (ISSN); 9781510608214 (ISBN) Saraygord Afshari, S ; Pourtakdoust, S. H ; Fiberguide Industries; Frontiers Media; OZ Optics, Ltd.; Polytec, Inc.; The Society of Photo-Optical Instrumentation Engineers (SPIE) ; Sharif University of Technology
    SPIE  2017
    Many modern industrialized systems such as aircrafts, rotating turbines, satellite booms, etc. cannot perform their desired tasks accurately if their uninhibited structural vibrations are not controlled properly. Structural health monitoring and online reliability calculations are emerging new means to handle system imposed uncertainties. As stochastic forcing are unavoidable, in most engineering systems, it is often needed to take them into the account for the control design process. In this research, smart material technology is utilized for structural health monitoring and control in order to keep the system in a reliable performance range. In this regard, a reliability-based cost... 

    Utility of probability density evolution method for experimental reliability-based active vibration control

    , Article Structural Control and Health Monitoring ; Volume 25, Issue 8 , 2018 ; 15452255 (ISSN) Saraygord Afshari, S ; Pourtakdoust, S. H ; Sharif University of Technology
    John Wiley and Sons Ltd  2018
    The utility of probability density evolution method for reliability-based active vibration control of a cantilevered flexible beam is experimentally investigated. In this respect, an optimal linear quadratic regulator (LQR) is utilized together with an observer to design an online full-state feedback controller. In order to design a well-performing controller and to simulate the controller performance, a system model is obtained via identification techniques. Reliability tests are consequently performed to verify the effectiveness of the presented reliability assessment method as a foundation for reliability-based control. Subsequently, a hybrid metaheuristic optimization scheme of... 

    Intelligent active vibration control of constrained manipulaors in robotic deburring

    , Article 2009 International Conference on Industrial Mechatronics and Automation, ICIMA 2009, Chengdu, 15 May 2009 through 16 May 2009 ; 2009 , Pages 76-80 ; 9781424438181 (ISBN) Daniali, M. M ; Vossoughi, G ; Sharif University of Technology
    In this paper, active vibration control of constrained manipulators used in automated deburring process is addressed. In order to suppress the random vibration generated due to the interaction force between robot end-effector and workpiece, an adaptive critic-based neurofuzzy controller is developed. This controller can adapt itself with different burr size. The control signal is fed to a piezoelectric actuator, which is mounted beside the workpiece. The piezoelectric actuator moves the workpiece to compensate the vibration. According to the intelligent behavior and system independent structure, the proposed design can be used for any industrial manipulator in various automated finishing... 

    Structural Assessment and Rehabilitation of Jacket Platform Structures with Regard to Remaining Life

    , M.Sc. Thesis Sharif University of Technology Rahimzadeh Khoshroo, Mohammad (Author) ; Golafshani, Ali Akbar (Supervisor) ; Tabeshpoor, Mohammad Reza (Co-Advisor)
    In this thesis, a novel approach for assessment and rehabilitation of offshore platform structures will be introduced, which is based on the fatigue analysis. Although fatigue is not a limiting criteria for platforms having natural periods bigger than two seconds, some of this platforms may be susceptible to fatigue due to their specific design. In addition, fatigue analysis can be an effective solution in cases like assessing the efficiency of structural control instruments under platform’s operational loads, and in its life. The main merit of this approach is that it can model the exact behavior of various damper devices and show their influence on the fatigue life. In fact, control... 

    Cracked Rotors Modeling for Vibration Analysis and Control

    , Ph.D. Dissertation Sharif University of Technology Ebrahimi, Ali Reza (Author) ; Behzad , Mehdi (Supervisor) ; Meghdari, Ali (Supervisor)
    The main aim of this thesis is to develop a mathematical model for vibration analysis of cracked rotors. This model should be a simple and precise model for prediction of the cracked rotor vibration behavior and suitable for vibration control. In order to create such model, the pure bending of a cracked beam is analyzed at first. This analysis is performed for two different orientations of the crack with respect to the beam and the bending vector. In this section a continuous bending model with continuous model for crack is developed which can predict the full deformation of the cracked beam in bending and can estimate the stress distribution in the beam with good approximation. Comparison... 

    Passive Control of Jacket Platforms and Determine Fatigue Life under Wave Loads

    , M.Sc. Thesis Sharif University of Technology Janbazi Rokni, Hossein (Author) ; Tabeshpoor, Mohammad Reza (Supervisor)
    Marine structures are always exposed to environmental loadings such as wind, wave, earthquake and sea currents. The wave-induced force could cause the critical stress in elements and due to fatigue failure, because of being random and periodical. In generally, it can be shown that fatigue is an extremely important phenomenon and one of the main problems in the long time destruction of the structure, because of severe corrosion and random loading in the marine environment.In order to reduce the effect of environmental loads, using control mechanisms is a new method to control vibrations of structures. These systems cause the reduction of structure responding such as acceleration, velocity and... 

    Active Vibration Control of Constrained Industrial Manipulators Using Piezoelectric Actuator

    , M.Sc. Thesis Sharif University of Technology Mohammadi Daniali, Mohsen (Author) ; Vossoughi, Gholamreza (Supervisor) ; Boroushaki, Mehrdad (Supervisor)
    Nowadays, due to the advancement of robotic technologies and development of industrial robots, the robot manipulators are widely used for automation of various manufacturing processes, such as finishing processes. In these applications, the contact has to be made between robot end-effector and environment. Therefore, control of interaction force in the constrained manipulators is an important demand. On the other hand, due to use of gear box and belts for energy transmission in robot joints, robot manipulators have flexible joints. The vibration, generated due to the interaction force and robot joint flexibility, can deteriorate surface roughness in automated finishing processes. In order to... 

    Introducing a new semi-active engine mount using force controlled variable stiffness

    , Article Vehicle System Dynamics ; Volume 51, Issue 5 , 2013 , Pages 721-736 ; 00423114 (ISSN) Azadi, M ; Behzadipour, S ; Faulkner, G ; Sharif University of Technology
    This work introduces a new concept in designing semi-active engine mounts. Engine mounts are under continuous development to provide better and more cost-effective engine vibration control. Passive engine mounts do not provide satisfactory solution. Available semi-active and active mounts provide better solutions but they are more complex and expensive. The variable stiffness engine mount (VSEM) is a semi-active engine mount with a simple ON-OFF control strategy. However, unlike available semi-active engine mounts that work based on damping change, the VSEM works based on the static stiffness change by using a new fast response force controlled variable spring. The VSEM is an improved...