Active Stiffener Concept for Shape Control of Two Dimensional Structures

A substantial amount of research exists concerning shape and vibration control of structures with attached piezoelectric ceramic sheet actuators. Researchers have investigated the optimal placement, size, and electrode pattern of these piezoceramic actuators to maximize the performance of the system. In many situations, the performance could be further improved with tailoring of the electromechanical properties of the actuator. For example, it was found that to avoid exciting higher order modes, the ideal actuator would be one that only actuates in one direction when controlling certain modes in a two-dimensional plate structure [1]. As known, the 31 and 32 electromechanical coupling values of a piezoelectric ceramic patch poled in the 3 direction is equal. Therefore to achieve decoupling of the actuator action in the 31 and 32 directions, a mechanism is required. In this paper, an active stiffener concept is proposed to realize such an effect where a stiffener is inserted between a host structure and the piezoelectric ceramic actuator patch. Using a solid finite element model, an analysis of a single active stiffener attached to a rigid and a flexible host structure is presented. In the analysis, the effects of various material and system parameters on the transmitted force to the structure are presented. It is seen that the active stiffener can significantly reduce the transmitted force in the selected direction. The performance of the active stiffener concept with multiple actuators is presented for controlling the shape of a large flexible circular plate structure.