Analytical and experimental studies for vibration control of smart composite structures have been performed. In this study a new finite element formulation has been proposed for the analysis of dynamic and control behavior of laminated composite plates with piezoelectric sensors and actuators. The linear piezoelectric constitutive equation and the layer-wise displacement plate theory have been used for the formulation of present finite element method. The developed finite element program can effectively consider the variable in-plane displacement through the thickness, the thickness variations due to partly bonded piezoelectric sensors and actuators, and more realistic boundary conditions. Several numerical examples show that inclusion of these effects is very important to evaluate closed loop performances of smart composite plates more exactly. In addition, the characteristics of piezoelectric actuator have been studied using experimental modal testing. Comparison of experimental and analytical results shows good agreements. In order to obtain efficient closed loop performances, genetic algorithms have been applied to find effective locations/placements of piezoelectric sensors and actuators. Especially the proposed method can be used to design the electrode patterns for the piezoelectric sensors and actuators. The hardware for the vibration control experiment was prepared. A DSP (digital signal processor) has been used as a digital controller. A quasi-isotropic composite plate specimen was selected as the experimental model. The configurations of the piezoelectric sensors and actuators have been determined using the proposed method, which is based on the genetic algorithms. This specimen has two sensors and two actuators. Using coupled positive position feedback control method, the vibration control experiment has been performed. Significant vibration reduction for the first three modes has been observed. Also the closed loop system was observed to be robust with parameter variations.
