This paper presents a novel flexible shape memory alloy (SMA) actuator, which is mainly composed of an SMA wire and a multilayer tubular structure. The multilayer tubular structure, which consists of a polytetrafluoroethylene tube, a metallic hose and a rubber tube, possesses the properties of good flexibility and high axial stiffness. The flexibility makes the SMA actuator easy to integrate into a compact or thin, narrow space with dimension constraints. The high axial stiffness helps in handling serious bending and prevents buckling of the SMA actuator. To verify the performance of the proposed actuator, a prototype was fabricated and a corresponding experimental setup was established. The effects of critical parameters, including heating current, winding angle, and applied load were experimentally investigated. The result demonstrates the feasibility of the proposed actuator and its easy integration into confined spaces. This work creates expanded opportunities for developing SMA actuators into broader application fields.

The shape memory alloy (SMA)-actuated separation devices that are currently used in small satellites were usually designed to handle large separation loads. As a result, they have complex structures, large footprints, and high power consumptions. In this paper, we report a simpler and more compact separation device. A design methodology for the load-shifting SMA actuator (LSSA) used in a device was developed. Four prototypes were fabricated and tested to demonstrate the design concept and the LSSA design methodology. Experiments showed that this separation device has the merits of a quick response time, compact size, and simple structure, which give it potential for small-satellite applications.