Active control of free and forced vibrations in piezoelectric smart structures

In this study, experimental and numerical analyses of actively controlled piezoelectric smart structures are carried out. Example smart structures with two different configurations are considered for the control of the free and the forced vibrations. Cantilever smart structures consist of aluminum beams with surface bonded Lead-Zirconate-Titanate (PZT) patches of Sensortech BM532. In the first example, a smart structure with a single PZT patch is used for the free vibration control under an initial displacement. In the second example, a smart structure with two PZT patches is used for the forced vibration control. Harmonic excitation is applied to one of the PZT patches placed in the middle of the beam. The other patch is used as vibration controlling actuator. A non-contact laser displacement meter is used as a sensor. Natural frequencies of the beams are found with chirp signals. Open loop and closed loop dynamic responses are obtained in the time domain to evaluate the effectiveness of the active control. Closed loop numerical solutions are performed in the finite element (FE) environment. Free and steady-state vibration amplitudes of two example smart structures are successfully reduced using displacement feedback control. It is observed that the experimental and numerical results are in good agreement