Investigation on the Hysteretic Behavior of NiTi Shape Memory Wires Actuated under Quasi-Equilibrium and Dynamic Conditions

The functional characterization of SMAs for actuation is typically performed by measuring the specimen deformation under constant load during a controlled thermal cycling across the transformation temperatures.

Aim of this work is to better investigate and understand the hysteretic behavior under dynamic actuation, verifying whether transformation temperatures may be different from those measured in quasi-equilibrium conditions or not. Direct and indirect heating of shape memory wires under several loading conditions are examined in detail. Experimental results will be presented and discussed.