Design of space systems using shape memory alloys

Abstract

Shape Memory Alloys (SMA) are a unique type of material characterized by two properties that ordinary metals do not exhibit: Shape Memory Effect (SME) and pseudoelasticity. SMAs can be actuated mechanically and/or thermally, and these properties have already been exploited in a wide variety of engineering applications. The appearance of SMAs in space applications, however, is more recent. This paper presents the motivations leading to interest for SMAs in space applications, as well as an overview of their use from tested mechanisms to ones still in development. As will be shown, many SMA space applications are single use and thermally activated. Although heating is never a problem, cooling SMA actuators in a reasonable amount of time still has to be achieved. A thermoelectric cooling system that allows for thermal control will be presented. This active cooling can allow better thermal actuation of SMA mechanisms using the two way SME. The last section of the paper describes their suitability for passive vibration isolation during launch, with a simple design using SMA hollow tubes at the interface between the payload and the spacecraft.