ACTIVE VIBRATION CONTROL OF STRUCTURE USING PIEZOELECTRIC PATCHES

Abstract

The work presented here deals with Active Vibration Control (AVC) of a Cantilever Beam with Piezoelectric Patches using Finite Element Method (FEM). One patch is used as a sensor, sending the signal in terms of voltage to the control system; while other is used as an actuator, which applies moments based on the signal (voltage) received from the control system. Newmark method of direct numerical integration has been used in the programmes coded in Matlab 5.3 to analyse transient responses. Negative velocity feedback control (NVFBC), Independent Modal Space. Control (IMSC) and Modified Independent Modal Space Control (MIMSC) are used to control both free and forced vibrations. In case of free vibration, it is found that with the increase in the value of Gain in -Negative Velocity FBC, the damping gets increased, while settling time reduces till some value of gain, after which response gets unstable. MIMSC gives better performance than IMSC, and in both, IMSC as well as MIMSC, damping and settling time increases with weighting factor(R); while the peak voltage i.e. control effort decreases with increasingR. In case of forced vibration with harmonic force input, steady state amplitude as well as maximum amplitude decreases with increasing gain in Negative Velocity FBC, till some value of gain after which response becomeunstable; while steady state amplitude and maximum amplitude increases with weighting factor R in MIMSC and IMSC. Control voltage decreases with increase in R in IMSC, MIMSC. In the case of forced vibration, IMSC gives better performance than MIMSC. The study of forced vibration with ramp input is carried out to achieve vibration control by varying axial stiffness of beam by applying same polarity voltage on both actuators bonded to the beam in collocated fashion. Control of vibration using variable axial stiffness during sweeping excitation has been investigated. When patches are activated from beginning and deactivated at about 50% of average of first natural frequencies with and without the axial stiffness variation, maximum amplitude of the vibration has found to be reduced substantially. Though cantilever beam has been considered, merely B anging boundary conditions (B.C.) the developed software can be used to analyse other types of beams.