A changeable aerofoil actuated by shape memory alloy springs

An aerofoil has great influences on the aerodynamic quality of aerial vehicles and efficiency of flight can be greatly improved by adopting the optimum aerofoil under different flying conditions. A changeable aerofoil model is designed and manufactured. By changing the constraint condition of the skins, they can achieve large deformation without overstepping their strain allowance. Shape memory alloy springs with the help of stop structures are used to actuate accurately certain points on the skins to approach the target aerofoil. A finite element model of the skins is built and deformation of the skins under the control of the discrete points is simulated. Deformation of the skins actuated by SMA springs is measured and the results of the experiment and simulation are compared and analyzed. A method of designing a changeable aerofoil is provided.