3621

3420

كارشناسي ارشد

كنترل

اصفهان: دانشگاه صنعتي اصفهان ،دانشكدة برق وكامپيوتر

1386

نه، 118 ، [II] ص:مصور، جدول، نمودار

ص. ع. به فارسي و انگليسي

سعيد حسين نيا، حميد رضا مير دامادي

7/5/86

فريد شيخ الاسلام، مجتبي ازهري

مهندسي برق و كامپيوتر

ID3420

به فارسي وانگليسي: قابل رويت در نسخه ديجيتالي

AbstractDuring decades one of the most challenging hazards for civilizations has been the risk ofseismic activity along with strong ground motion called earthquake Many civil structureshave been destroyed along with the civilization Great improvements have been established inthe exact analysis and design of high rise buildings and wide span bridges subject to thevibrations of the earth However recently there have been considerable attentions to viewthese structures as dynamical systems and to control their intractable dynamics against thevibrational motions and dynamic loadings instead of strengthening them The challengingfield of mechanical structural vibration control of structures was gradually transferred fromthe field of civil and mechanical engineering to the control and system engineering communityand attracted the attention of many researchers in these fields This thesis focuses on the vibration control of a smart composite cantilever beam consisting ofan elastic core layer as the host beam and two piezoelectric outer layers acting as the sensorand actuator The classical kinematics theory of Euler Bernoulli is used for establishing strain displacement compatibility relations The Hamiltonian mechanics formulation is used toestablish the momentum equations of Newton and the kinetics equations of the motion Thelinearized theories of elasticity and piezoelastoelectricity are applied as the constitutive lawsof material to complement the kinematics and kinetics equations of the continuum Thedisplacement based finite element method is then adopted in order to numerically model thesmart composite beam and to calculate the dynamic characteristics of the matrices of thediscretized system namely the mass and stiffness matrices For this purpose in addition to the six mechanical degrees of freedom for every finite element two additional electrical degrees of freedom were considered for the above mentionedpiezoelectric layers The damping matrix is built up using the Rayleigh method The vibration control of this structure is based on an electromechanical interaction ofpiezoelectric layers with elastic parts Furthermore unmodeled dynamics and future damagesto the structure which may cause some uncertainties in the structural parameters areconsidered In order to model these parametric uncertainties the linear fractionaltransformation LFT method is used The controller uses the synthesis approach in order toreduce undesirable disturbances dynamic loadings and also to avoid closed loop systeminstability caused by perturbations In order to demonstrate the importance of the modeling ofuncertainties the process of designing an H controller is presented for a nominal system atthe first part of controller design along with executing some numerical simulations for acorresponding nominal beam model At the second part the proposed controller is presentedfor a perturbed beam model along with the related simulated results At the end some simulated results are presented for the case of two piezoelectric patchesplaced on just one of the finite elements near the foundation of the beam

سعيد حسين نيا، حميد رضا مير دامادي

فريد شيخ الاسلام، مجتبي ازهري