Development of hydraulic linear actuator using thin film SMA

In this paper, thin film (10 μm) nickel-titanium (NiTi) shape memory alloy (SMA) was used to develop a compact actuator pump generating high output force at large velocities. The velocity was dependent on actuation frequency of the thin film NiTi membrane operated at 10, 50, and 100 Hz. The liquid flow also provided forced convection cooling of the NiTi membrane. The inlet and outlet pressure were always at equilibrium prior to actuation and the inlet pressure biased the NiTi membranes. Experimental results show that the optimum operating output load was 98 N, and the blocking force was 198 N. The peak velocity of 5.85 mm/s (2.96 cc/s) was obtained while operating the membrane at 100 Hz. Analytical predictions provide general trends observed experimentally. Actual measurements were smaller than predictions (i.e. peak velocity of 13.9 mm/s which corresponds to 7.03 cc/s) due to assumed constant pressure in the model.