Shape Memory Alloys are materials that can expand or contract according to temperature variations and then return to their previous form.

A group of researchers from Texas University, under prof. Othon Rediniotis, is exploring the possible use of these materials in order to build small ships that can move silently and without leaving wake traces.

High flying aircraft and ocean surveillance satellites identify and monitor the movement of ships not by spotting the vessel itself but the wake created from the rotating screws. The same applies for submarines that are moving close to the surface.

The research group is studying the movement of fish and more specifically the expansion and contraction of their muscular cells, in order to reproduce it for the propulsion of small ships for the US Navy. To achieve the reproduction the group is using cables constructed by Shape Memory Alloys (SMA). When the cables are heated, their length is altered by 8%. Using springs and adapting the cables to a metal frame the ship can move like a fish by switching between warm and cold cables.

Dr Othon Rediniotis is a member of the SMART team (Shape Memory Alloy Research Team) that is currently working on several SMA applications, ranging from orthodontics and coffee machines to aeronautical engineering and earthquake protection. The SMART team is headed by Dr Dimitrios Lagoudas.