Morphing flap driven by link with antagonistic shape memory alloy wires

Abstract This paper describes a study of a morphing flap using antagonistically arranged shape memory alloy (SMA) wires as actuators. The main focus of this study is to examine how existing aircraft structures and mechanisms can be modified to make the morphing airfoil more practical. The first step is to consider the drawbacks of existing morphing airfoils and then examine the advantages of the morphing airfoil proposed in this study. Then, a morphing airfoil is proposed to realize four significant technical issues: weight reduction, compatibility with existing structures, securing internal space, and seamless skin made with shape memory polymer (SMP) films. First, elemental experiments were conducted to examine the feasibility of the mechanical design, and the feasibility of the design of a large-morphing airfoil operating test model was confirmed. Next, aerodynamic and structural-mechanical analyses are conducted while designing the experimental operating model to verify whether it could operate up to the target flap angle under simulated flight conditions. After completing the experimental model, actuation tests are conducted as a morphing wing and confirm whether the wing could operate at the target flap angle in a realistic environment. As a result, the two-way morphing flap angle was experimentally observed. It is noted that only aerodynamic force was not considered in the experiment, which is further investigated in wind tunnel tests in future study. In addition, control rate of the proposed system seems improved than conventional model because of the reduction of the wire length of the actuation system. Thus, the results obtained in this study suggested the proposed link-driven SMA wire mechanism can be applied to make the morphing airfoil more practical.