Elastic composite skin for a pure shear morphing wing structures

This study is focused on developing a morphing skin that can perform ±30° pure shear morphing. Carbon fibre–reinforced plastic rods–reinforced and Kevlar-reinforced silicone rubber matrix composite skin is designed, fabricated, tested, and utilized on the demonstrator wing. This skin design has achieved satisfactory wrinkle onset angle (>50°) without applying pre-tension or pre-stretch, low in-plane shear stiffness that allows the skin of 1 m² to perform 30° shear morphing under 30 kg actuating force, designable out-of-plane stiffness, considerable damage tolerance, and simplicity in fabrication. This article describes the designing process of the skin, where a carbon fiber–reinforced plastic rod–reinforced skin is tested and revised to the final design; the study on the mechanism of different types of wrinkles as well as the strategies of wrinkles reduction, where two complementary wrinkle characterization methods are used; analysis and testing on out-of-plane stiffness; and finally, the utilization of skin on a demonstrator morphing wing structure. The presented skin can also be used as morphing face sheet.