In recent years, space structures are expected to be larger for high performance. Additionally, they are required to be lightweight due to weight limitation in rocket launches, and lightweight materials such as CFRP are used in space structures. Large and lightweight space structures tend to be flexible, and the structures vibrate easily. Since vibrations are hard to decrease in the space environment of high vacuum, they may degrade the performance of structures. Therefore, it is important to suppress these vibrations.
Piezoelectric materials are electromechanically coupled, and can convert the mechanical energy of structures into the electrical energy and also the electrical energy into the mechanical energy. Therefore, a great amount of research has been devoted to combinations of piezoelectric materials and electric equipment to suppress vibration of structures. Some ideas have been proposed for recycling mechanical energy to enhance the performance of semi-active vibration suppression where the energy is converted from the vibrating structure through a voice coil transducer or a pneumatic device. A method of semi-active vibration was also proposed when the mechanical energy is used to suppress vibration by an electric circuit with an inductor. Moreover, an energy recycling method that enhances semi-active vibration suppression with piezoelectric transducers was proposed. But no one has mentioned the limitation of the energy recycling method. It is important to know the limitation of this system in a design of the structures which include the energy recycling vibration control system.
The limitation of vibration effect is presented in this paper. In order to verify the characteristics between damping effect and lost energy, free vibration test of passive damping are carried out with a CFRP cantilevered beam. The effect of vibration control in the energy recycling method is compared with that in the active vibration control.
edited by Itsuro TSUCHIDA