Extraction of System Model from Finite Element Model and Simulation Study of Active Vibration Control

Theglobalcompetitionisspearheadingthedesignoflightermechanicalsystemscarryinglighterloadsat higherspeeds.Thisissueisparticularlyimportantforspaceandaircraftstructures.However,thisleadsto highervibrationwhichinturnaffectsthelifeofsystem.Hence,controlofvibrationisessential.Theactive vibration control can be effectively used to control these vibrations. In this paper an attempt is made to implement optimal control strategy for active vibration control of a dynamic system. In active vibration control the controller plays an important role. For designing the controller the required system model is extracted from its Finite Element (FE) Model. For validation of the study, a two degree of freedom (dof) system is considered and performed the analysis. The extracted model is compared with the models obtained by conventional techniques for checking its validity. The Linear Quadratic Regulator (LQR) control strategy is used with state feedback control law for designing the controller and the obtained control gains are used in simulating the control action in both MATLAB © and ANSYS © . The vibration responses generated from MATLAB © and ANSYS © are compared for validating the methodology. To demonstrate the methodology a case of cantilever beam is considered. The piezoelectric actuators are used in the present study. In case of cantilever beam both full and reduced models are used for designing the controller and the resulting responses are compared. The effect of selection of weighting matrices of performance index of LQR on the performance of optimal controller is also reported. The feasibility of using reduced model for designing optimal controller is checked by comparing its response with that of full model. A lot of computational time can be saved, if the reduced models are used for designing the controller for active vibration control of real life complicated systems.

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