A Super-Elastic Torsion Rod For Small Wing Unfolding

Discussing SMAs usage in the aerospace industry is related usually to actuators. Such actuators use the shape memory effect in which the alloy is heated above A_f temperature in order to achieve a specific actuation. Yet, the super-elastic effect which allows even higher recoverable strain is often neglected. Main reasons for that are temperature dependency of the retained force and the necessity of other actuator or latch in-order to receive the motion at a specific event.

This talk suggests the usage of super-elastic torsion rod as a spring replacement for wing unfolding of a small projectile. The super-elastic torsion rod allows volume reduction to less than 50% from a conventional music-wire torsion spring usage. The talk will cover both architecture design consideration and a novel bi-linear approach for torque calculations during the torsion. Such approach allows the designer simple direct analytical calculations, eliminating the need of finite element expertise.  Design, calculations and test results will be discussed.