Surface actuated variable-camber and variable-twist morphing wings using piezocomposites

A surface actuated variable-camber morphing airfoil employing a type of piezoceramic composite actuator known as Macro-Fiber Composite is presented. The proposed airfoil employs two cascading active surfaces and a pair of optimized pinned boundary conditions. The optimized locations of pinned boundary conditions and the geometric features allow for a variable and smooth deformation in both directions from a flat camber line. The continuity of the airfoil surface is achieved by using a single substrate that wraps around the airfoil shape. This substrate forms the surface of the airfoil and it serves as the host material for the two cascading bimorph actuators. The cascading bimorphs are pinned together at the trailing edge with a compliant hinge, which is also formed by the substrate material. The paper focuses on the theoretical static-aeroelastic response characterization. A parametric study of the fluid-structure interaction problem is employed to optimize the geometric parameters and the boundary conditions of the variable-camber airfoil. The coupled treatment of the fluid-structure interaction allows the realization of a design that is not only feasible in a bench top experiment, but that can also sustain large aerodynamic loads. The paper identifies the effects of four important structural parameters to achieve the highest possible lift coefficient and lift-to-drag ratio. Practical recommendations are presented to achieve a working prototype.