Novel shape memory actuators

In order to develop novel shape memory actuators, the torsional deformation of a shape memory alloy (SMA) tape and the actuator models driven by the tape were investigated. The shape memory composite (SMC) belt composed of SMA tapes and a shape memory polymer (SMP) was fabricated, and the three-way bending characteristics were also investigated. The results obtained can be summarized as follows. In the SMA tape subjected to torsion, the martensitic transformation appears along the edge of the tape due to elongation of the edge of the tape and grows to the central part. The fatigue life in both the pulsating torsion and alternating torsion is expressed by a unified relationship of the dissipated work in each cycle. Based on the two-way motion of an opening and closing door model and a solar-powered active blind model driven by two kinds of SMA tape, it is confirmed that the two-way rotary driving actuator with a small and simple mechanism can be developed by using torsion of the SMA-tape. The SMC belt laminated with the SMP tape and SMA tapes was fabricated. The three-way bending movement of the SMC belt was achieved during heating and cooling based on the characteristics of the SMA tapes and the SMP tape. The active SMC actuator with various three-dimentional movements can be developed by applying the three-way properties of the SMC.