2022 Volume 70 Issue 4 Pages 128-136
Morphing wings have various possibilities to realize drag and noise reduction and to extend flight envelope by smoothly changing wing shape during flight. This study focuses on the application of Shape Memory Alloy (SMA) wires as a lightweight actuation mechanism for morphing wings because SMA has a large recovery stress per unit mass. To achieve the required actuation stroke for the SMA wires, it was considered to design the spiral configuration of the SMA wires. This research experimentally observes the relationship between the recovery strain as the actuation performance of tube-guided wires and its geometric parameters such as spiral angle. It was found that the friction force between the SMA wire and its spirally guiding tube plays an important role on the actuator performance, and the performance gradually decreased as the length of the wires and the number of spirals increased. Furthermore, the application of the spiral configuration of SMA wire for a small aircraft was investigated. As a result, the effectiveness depends on the coefficient of the friction between the SMA wire and the spiral tube. Thus, the results obtained in this study could be used to properly design the tube-guided SMA coil-type actuators for morphing wings considering the effectiveness and challenges in its implementation.
