Session: 04-08: Emerging Integrated System Applications

Paper Number: 98915

98915 - Novel Method to Fabricate Monolithic Niti Based Torque Tubes Using Electrical Discharge Machining 

Development of SMA torque tubes over the past decade has resulted in a feasible monolithic device capable of achieving rotary actuation.  Owning to its simplicity, where the material itself is the sole rotary moving part, SMA tubes have become attractive for applications where space and weight are the limiting factor for a given design. This includes aerospace applications where they are integrated in structural surfaces to enable morphing for airflow control. However, the current fabrication methods for SMA tubes involves extensive machining (i.e. Gun drilling and honing), which adds complexity and costs that limits their development and commercial adoptions. More specifically, current fabrication processes often require a range of tools and set-ups to achieve varying tube parameters, including wall thickness, surface finish and spline design. The current work presents a novel method to fabricate NiTi based torque tubes using electro discharge machining by implementing a hole drilling and wire machining process. Detailed mechanical and metallurgical analysis was conducted to characterize performance and microstructure to ensure reliable and consistent actuation was achieved. Results showed that EDM fabricated tubes demonstrate both actuation and biasing abilities comparable to existing fabrication processes. This novel rapid fabrication method can enable mass adoption and integration of these devices for cost sensitive applications.

Presenting Author: Siu Kei Tang Smarter Alloys