Smart Skin and Actuators for Morphing Structures

Morphing technology on aircrafts has found increased interest over the last decade because it is likely to enhance performance and efficiency over a wider range of flight conditions. The key technologies in morphing aircrafts include adaptive structures, deformable smart skin, driving actuators, flight dynamics and flight control. Among them, the deformable smart skin and light-weight driving actuators have been the main obstacles to the real-world implementation of the morphing aircraft. The difficulties in the smart skin rest on the contradiction between its ability to resist aerodynamic load in the normal direction and the in-plane flexibility for morphing functions. This contradiction cannot be solved by using sophisticated properties of the skin materials. It can only be solved by new skin structures, which give anisotropic stiffness for bending and in-plane deformation. In this article two skin structures for morphing aircrafts, the wavy skin structure and the honeycomb skin structure, are introduced. The actuators for morphing aircrafts are required to have large stroke, large output force, good compactness, and good controllability. In this article, piezoelectric-hydraulic actuators are introduced.