Numerical modelling and experiments of a vibration suppression solution via Offset Piezoelectric Stack Actuators for space structures

Most of modern satellites for Earth and Universe observation are equipped with large flexible appendages to achieve their mission objectives. However, the fulfilment of pointing and stability requirements may be jeopardized by undesired elastic vibrations of such flexible parts, due to the coupling between spacecraft rigid and elastic dynamics. Therefore, control solutions aiming at avoiding instabilities and, at worst, the failure of the mission, are currently needed. In this scenario, growing interest has been recently devoted to Active Vibration Control (AVC) strategies relying on the use of smart materials. Among them, piezoelectric patches are the most studied and tested devices for both actuating and sensing purposes. This paper aims to contribute to this line of research by investigating a different type of actuator, namely an Offset Piezoelectric Stack Actuator (OPSA), to assess its performances in damping out elastic vibrations of large space structures. Moreover, special attention is devoted to compare OPSA performance with standard patch actuators behaviour. In order to develop the AVC system, an equivalent electro-mechanical coupled Finite Element (FE) formulation is implemented, integrating both sensors and piezo-stack elements on the passive hosting structure. The final structural model including both electrical inputs/outputs, as well as modified mass and stiffness due to the additional piezo devices, is then obtained. A parametric analysis is carried out to optimize the maximum control action exerted by the OPSA device. Finally, the OPSA developed numerical model is experimentally validated in the case of a cantilever plate, representative of a scaled solar panel. Experimental data will be used not only to verify the expected performance, but also to tune the parameters in the OPSA FE model, that can be finally integrated in a satellite attitude simulator to assess the AVC system performance during typical attitude manoeuvres