Vibration control of composite plates under random loading using piezoelectric material

A study of the use of H-infinity control design to suppress the vibrations of composite plates with embedded piezoelectric actuators under random load ing is presented. The finite element method is employed to obtain the dynam ic equations of plate vibration. The finite element model includes fully co upled structural and electrical nodal degrees of freedom. The modal reducti on method using the structural modes is adopted to reduce the finite elemen t equations into a set of modal equations with fewer degrees of freedom. Th e modal equations are then employed for controller design and time domain s imulation. The results of the modal convergence studies of the closed-loop systems show that the truncated modes, which are neglected in the control d esign, deteriorate the controller performance and affect the optimal locati on and size of the actuator. The vibrations of plates subjected to off-reso nant narrow-band excitations cannot be suppressed significantly. The contro ller shaped with an extra weight function for mitigating measurement noise gives better vibration reduction performance.