Development of a small reusable space release device using SMA

Development of advanced lightweight solar arrays and small satellites requires deployment and release devices to be very small and lightweight. Achieving release requirements through a small size device will face more challenging design problems. The SMA (Shape Memory Alloys) devices designed so far have all been discrete point bolt release devices. When several release devices are used, it is very hard for present SMA devices to keep synchronous because of a long individual separation time. This paper will describe the advantages of a new type of space release device actuated with SMA wire, the design and experimental results to demonstrate its functions. The scheme is to take advantage of the ability of SMA to recover a parent shape when heated by an electrical current. A clever and simple structure design ensures small size and light weight of the device. To achieve high release reliability, Tanaka-Liang's constitutive model was selected to describe SMA wire's deformation and response characteristics. Ground test facilities were designed to validate numerical prediction. Tests results showed that the small release device actuated with SMA wires can response very quickly (within 0.1 seconds under satellite power supply of 28V). Synchronous deployment tests were also done when two release devices were installed at the same time, and also gained success. It is concluded that the developed SMA release device owning advantages of small size, lightweight, low shock, no contamination, easy reset and synchronization etc. will play an important role in developing future advanced lightweight solar arrays.