Distributed vibration control of flexible structures using piezoelectric materials has been extensively studied for decades. A number of design configurations of distributed actuators with uniform control forces and moments have been investigated to improve modal control effectiveness of distributed structures, e.g., shells and plates. In this study, a new skew-quad actuator design which consists of four pieces of mono-axial piezoelectric actuator is proposed and evaluated. Due to the uneven boundary conditions of each region, this new actuator can induce non-uniform control forces and moments. Based on the variation method, the non-uniform distribution of the actuator induced forces and moments are defined. The coupling equation of a simply supported plate laminated with this new design is derived; distributed control action resulting from the non-uniform control moments is also defined in the modal domain. The actuator induced control actions are calculated respectively on a square plate and a rectangle plate, and the effects of varying actuator size are also evaluated. These control effects of the skew-quad actuator are compared with those of a multi-DOF actuator. Parametric analyses suggest that due to the non-uniform control moments, the new skew-quad actuator induces better modal control actions in certain plate modes as compared with the multi-DOF actuator. This new skew-quad actuator has great potential to improve control effects to other shell structures.
Synthesis of modal control in servo system with a differentiating observer
