Speaker
Description
Thermal one-way effect Shape Memory Alloy (SMA) actuators are a lightweight, robust and cost effective alternative to conventional actuators like pyrotechnics or electromagnetic actuators. Parts machined from SMA could be pseudo-plastically deformed in cold state, later they return to their previously machined shape by simply heating them up to their phase transformation temperature. During this process, strokes in the order of several percent of the actuator dimensions and high forces in the kN range are possible. Due to the fact that only a simple resistive heater is needed, the mechanism could be designed very robust and re-liable. Regarding valves for a one time application (normally open or normally closed) onboard of a space-craft, SMA actuators have several advantages, most notably their unlimited lifetime, the absence of pyro-technical shocks, no handling and transport constraints and lower cost.
The first section of this paper describes the fundamental principles of shape memory alloy metallurgy and the manufacturing steps of an SMA actuator as well as a briefly overview of the performed qualification tests.
The second section highlights the specified performance data, the operation principle and design features as well as recommended mounting/integration of the Ariane Group shape memory valve in a propulsion subsystem.
Within the third chapter, the qualification status including activation tests performed with real propellants (Hydrazine, MMH and MON) are presented as well as an outlook to the first flight applications of the device.
