Article Title

Influence of thin-film device with curvature on natural frequency of rectangle membrane under uniaxial tension


membrane structures, thin-film device, vibration, eigenvalue analysis, experiment


A solar power sail demonstrator “IKAROS” demonstrated solar sailing technology in 2010.The membrane of the spinning solar sail IKAROS is estimated to be deformed toward theSun. The deformation was kept even under low spin-rate. Previous studies suggest thatcurvature of thin-film solar cells on the membrane increases the out-of-plane stiffness by finiteelement analysis. Shape, out-of-plane stiffness, and natural frequency of membranes have tobe predicted for solar sails with thin-film devices, such as thin-film solar cells, dust counters,and reflectivity control devices in order to reduce the margins of sail size and propellantmass against disturbance solar pressure torque acting on the membrane. In this paper,the effect of a curved thin-film device on the natural frequency of a rectangle membraneunder uniaxial tension was investigated. Three types of membranes were evaluated: amembrane with a curved thin-film device, a membrane with a flat thin-film device, and aplane membrane. Geometric nonlinear finite element analysis and eigenvalue analysis wereconducted to investigate the natural frequencies under varying tension. The simulationswere verified by vibration experiments. It was found that under low tension, the naturalfrequency of the membrane with the curved thin-film device is significantly higher than thatof the others and that under high tension, the natural frequency of the membrane with thethin-film device is slightly lower than that of the plane membrane. In addition, parametricanalysis on the curvature of the thin-film device shows that natural frequency at low tensionis sensitive to the curvature. The eigenvalue analysis of a whole solar sail with the curvedthin-film devices also suggests that the curvature remarkably affects the vibration modes.In conclusion, curved thin-film devices have a significant impact on the out-of-plane stiffnessof a membrane under low tension.


Tsinghua University Press