反った膜面デバイスが1軸張力下の矩形膜の固有振動数に与える影響

抄録

The membrane of a spinning solar sail IKAROS is considered to be deformed toward the Sun. The deformation was kept even under low spin rate. Previous studies suggest that curvature of thin-film solar cells on the membrane increases the out-of-plane stiffness. For a solar power sail OKEANOS, the shape, out-of-plane stiffness, and natural frequency have to be predicted. In this paper, the effect of a curved thin-film device on the natural frequency of a rectangle membrane under uniaxial tension is investigated. Three types of membranes are evaluated: a membrane with a curved thin-film device, a membrane with a flat thin-film device, a plane membrane. Geometric nonlinear finite element analysis and eigenvalue analysis are conducted to investigate the natural frequencies under varying tension. The simulations are verified by vibration experiments. It is found that under low tension, the natural frequency of the membrane with the curved thin-film device is significantly higher than that of the others and that under high tension, the natural frequency of the membrane with the thin-film device is slightly lower than that of the plane membrane. The results show that curved thin-film devices have a significant impact on the out-of-plane stiffness of a membrane under low tension.