Stabilized actuation of a novel NiTi shape-memory-alloy-actuated flexible structure under thermal loading

摘要

Shape-memory-alloy (SMA) actuated flexible structures are used in a variety of configurations in many aerospace, robotics and underwater applications. In this study, a pair of nickel-titanium (NiTi) shape-memory-alloy plates is embedded in a flexible structure. An antagonistic design with a plate geometry is selected for the NiTi SMA to achieve bidirectional flexibility. A three-point-bending test is conducted to reveal the bending strength of the NiTi plates in the martensite and austenite phases. The antagonistic NiTi SMA plates are geometrically adapted and embedded into the flexible structure, which is fabricated through additive manufacturing using thermoplastic-polyurethane (TPU) flexible filament. The stabilized actuation stages of the antagonistic NiTi SMA plates embedded in the flexible structure are examined through observation of an extended number of thermal cycles. A comparison is made by applying two different electrical-current values with a regulated high-current DC power supply. A cycling profile with a maximum, bidirectional, stabilized actuation stroke of 52 mm is obtained through 100 heating/cooling cycles for the NiTi SMA-plate-actuated flexible structure. The effects of the high and low heating/cooling cyclic periods on the stabilized actuation stroke are also investigated. Keywords: shape-