كنترل ارتعاشات پوسته استوانه اي با بهينه يابي مكان وصله هاي پيزوالكتريك

چكيده انگليسي :

Vibration control of a cylindrical shell by optimizating the positions of piezoe lectric patches Mojtaba Biglar m biglar@me iut ac ir 15th August 2012 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Mohammad Danesh danesh@cc iut ac irAbstractVibrations are a part of our environment and daily life Many of them are useful and are needed for manypurposes one of the best example being the hearing system Nevertheless vibrations are often undesirableand have to be suppressed or reduced as they may be harmful to structures by generating damages or com promise the comfort of users through noise generation of mechanical wave transmission to the body Vibra tion control and limitation is an exciting eld in the research community and raises challenging issues in in dustrial applications This topic involves multidisciplinary approaches and multi physic coupling from me chanical to thermal and possibly through electrical or magnetic elds the basic idea being the dissipation ofthe mechanical energy into heat or preventing mechanical energy from entering into the structures Twostrategies are typically used for limiting vibrations The mechanical energy may be directly dissipated intoheat through the use of viscoelastic layers or the use of additional stiffeners can prevent energy from enteringin the system but the performance of such approaches is limited especially in the case of low frequency vi brations In order to dispose of ef cient systems the second method consists of using intermediate energyconversion media such as electromagnets or piezoelectric actuators When using multiphysic coupling me chanical energy is rst transferred into another form electrical magnetic before being dissipated Energyconversion systems may also be used to ensure that the input force spectrum does not overlap the frequencyresponse function of the structure to ensure that no energy goes into the device To limit the vibrations of asystem many methods have been proposed such as passive control schemes semi passive techniques activecontrol schemes ect Active vibration reduction of structures is one of the most important challenges thatmany of researchers have paid attention to it in recent years Active vibration control is one of the techniquesthat is used for decaying structural vibrations Many materials such as piezoelectric materials shape memoryalloys electrostrictive materials electromagnetotstrictive materials electro and magneto rheological fluids etc can be used for suppressing vibrations The application of piezoelectric materials have become popularbecause of low weight high strength high stiffness high frequency response and easy implementation Inthis study the active vibration control of a cylindrical shell using piezoelectric sensors and actuators are ana lyzed The boundary condition of a cylindrical shell is simply supported and the piezoelectric patches areattached to its surface locally Firstly the continuous model of system is derived by using terms of energy virtual work and Hamilton s principle Then the Rayleigh Ritz method is used for deriving the dynamicmodel of a cylindrical shell and piezoelectric sensors and actuators based on Donnel Mushtari shell theory In next step the major goal is to find the optimal location of piezoelectric sensors and actuators on the cylin drical shell The optimization procedure is designed based on desired controllability and observability of eachcontributed and undesired mode Further to limit spillover reduction the residual mode is regarded The op timization variables are positions and orientations of piezoelectric patches Genetic algorithm is utilized toevaluate the optimal configurations For active vibration control a negative velocity feedback control algo rithm is used Finally the arbitrary locations of patches dimensions of shell orientations of paches on theshell patches sizes and their number applied voltage and applied mec

بيگلر، مجتبي

كنترل ارتعاشات پوسته استوانه اي با بهينه يابي مكان وصله هاي پيزوالكتريك

روش ريلي-ريتز , الگوريتم ژنتيك