Vibration suppression of two-panel structure via stiffness-tunable joints

Spacecraft solar panels, characterized by low stiffness and weak damping, are prone to produce continuous low-frequency and large-amplitude vibrations under external disturbances in microgravity. To address these challenges, a semi-active method for low-frequency vibration mitigation in spacecraft solar panels using novel Magnetically-Controlled Stiffness-Tunable (MCST) joints is introduced in this study. First, a new configuration of a panel-type spacecraft with multiple MCST joints is proposed, featuring three outstanding advantages: electromagnetic direct-drive, integrated structure and function, and vibration suppression through frequency shift via joint variable stiffness. Second, an analytical dynamic model for a two-panel structure connected by MCST joints is developed using the Rayleigh-Ritz method, explicitly incorporating joint dimensions, mass, and rotational inertia. Then, the natural frequencies and corresponding global mode shapes are determined. Finally, an experimental platform of the two-panel system was constructed to simulate space microgravity conditions. The effectiveness and precision of GMM were confirmed through comparative studies of dynamic models obtained by global mode method (GMM), finite element method (FEM), and experiments. Furthermore, ultra-low-frequency (0.01 Hz) vibration suppression was achieved under non-contact hybrid excitation composed of permanent magnetic and airflow. The results indicated the amplitude reductions of 80.27 % for Panle-1 and 75.16 % for Panle-2 at 0.01 Hz, respectively. These findings present an innovative approach for controlling the low- and ultra-low-frequency vibrations in large space flexible hinged panels.