Double-Layer Deformable Honeycomb Flexible Skin Design for Seamless Trailing Edge Flap

Flexible skin is an indispensable part of the morphing wing. Researchers proposed many kinds of flexible skin with different properties for different deformation modes and different deformation parts of the morphing wing. In this paper, a new type of double-layer honeycomb structure was proposed. The structural composition and deformation mechanism of double-layer deformable honeycomb were expounded. The in-plane and out-of-plane properties of double-layer deformable honeycomb flexible skin were studied by theoretical, finite element simulation methods, and experimental studies. The proposed flexible skin exhibits characteristics of large in-plane deformation, near-zero Poisson’s ratio, and sufficient out-of-plane load-bearing capacity. A parametric structural analysis was conducted, and the parameters were tailored to meet the application requirements of seamless trailing edge flaps. The designed flexible skin not only satisfies the requirement for large-angle deflection of trailing edge flaps with a smooth and continuous surface but also demonstrates a 3.0% increase in lift coefficient and a 2.8% improvement in lift-to-drag ratio compared to conventional seamless trailing edge flap.