Development and testing of a corrugated skin for a camber morphing aerofoil

This work presents the development and testing of a corrugated skin for the Fish Bone Active Camber (FishBAC) morphing airfoil concept. This novel biologically inspired morphing structure consists of a compliant skeletal core composed of a thin chord wise bending beam with periodic stringers, a compliant external skin structure and an actuation mechanism. One of the critical components of this morphing structure is the anisotropic skin which has to be stiff to withstand the aerodynamic loads and flexible to enable the morphing deformations. The good in-plane strain capability and highly anisotropic behavior of composite corrugated panels makes them very effective in morphing wing applications where the panels are stiff along the corrugations to withstand the aerodynamic loads and flexible transverse to the corrugations to allow deformation. Recently, the static behaviour of composite corrugated panels has been investigated independently of the internal wing structure through experimental analysis, numerical simulations and analytical equivalent modeling. However, as a proposed candidate for the skin of a morphing wing, the manufacturability of the corrugated panels and the feasibility of integration must be investigated comprehensively with different materials. Hence, the paper is structured in three parts. The first part gives a summary of the geometric parameters of the corrugated panels that are optimized to minimize the in-plane stiffness and the weight of the skin and to maximize the flexural out-of-plane stiffness of the corrugated skin. The second part is mainly focused on the development of the composite corrugated skin using commercially available Kevlar. Finally, standard tensile tests were performed on the manufactured corrugated samples to evaluate their material characteristics. The advantages of the proposed technique used for the composite corrugated skin manufacture for the FishBAC morphing structure are discussed.