SMA Actuator Research Applied In Space Deployable Mechanism

The solar panels are the main energy supply system of the spacecraft. During the process of sending and entering into orbit for the spacecraft, the solar panels undergo two stages: folding and deployment. This paper studies a SMA(Shape Memory Alloy) actuator used in space deployable mechanism. A SMA torsion actuator which is based on the SMA actuator as the research object and the solar panels deployable mechanism as an example is designed to open the solar panels.Firstly, this paper introduced the development, classification and driving mode of space deployable mechanism. SMA materials were proposed in the solar panels deployable mechanism and shape memory effect was explored. Based on SMA constitutive model, SMA was simulated by Matlab and a SMA torsion driving mode was presented.Secondly, the torque output of SMA actuator was analyzed theoretically, assuming that temperature was the only factor affecting the SMA phase transition. The relationship between torque output and angle was obtained when SMA actuator was in high temperature. After the development of solar panels was analyzed, the formulas of deployment velocity, angular velocity and angular acceleration were presented. The solar panels were affected by air resistance and the deployment mechanism’s internal friction, during the process of the test carried out on the ground. The drag torque was obtained through calculation and experimental measurement. A torsional spring was designed based on SMA working as driving material. The phase-transition temperature of SMA materials was measured. A test system was designed. After manufacturing and testing the driving element, the torsional spring can be chosen accordingly. Compared with the drag torque of the solar panels deployment process, this torsional spring was feasible.Finally, the SMA torsional spring was assembled on the solar panels. During the test was carried out on the ground, the time of opening the solar panels is 15.4s. When the solar panels were at 180°, the moment of SMA torsional spring is 8.54N·mm, which was kept the solar panels open.