<title>Active stiffeners for shape and vibration control of circular plate structure</title>

Abstract

In high precision space optical systems, it is critical that the structure maintains a near-perfect surface. Previous studies investigated the performance of utilizing piezoelectric ceramic patches for reducing the surface error. The research results demonstrated that the two-dimensional actuation effect of the actuator patches could induce high order modal deformations and cause undesired surface error. It was discovered that decoupling the circumferential and radial actuations of the sheet actuators could improve the system performance. To realize the decoupling effect, an active stiffener design is proposed and analyzed in this paper, where a standoff layer is inserted between the host structure and the piezoelectric ceramic sheet actuator. The stiffener acts as a decoupling mechanism which reduces the transmitted action in one direction while allowing adequate action to be transmitted in the orthogonal direction. For the analysis, a 3-D solid finite element model of a thin circular structure containing stiffeners and piezoelectric ceramic actuators is developed. It is shown that the active stiffener design achieves a smoother surface, corrects for more surface error, reduces controller spillover, and improves system stability.