Morphing skins

TLDR

Morphing technology on aircraft has attracted growing interest over the past decade because it can improve performance and efficiency across a wide range of flight conditions, yet few concepts address the challenge of a smooth, continuously deformable skin that also carries loads. This review surveys morphing concepts with a strong focus on morphing skins. The authors examine structures that transmit primary loads spanwise while achieving morphing through chordwise flexibility, including tailored or actively controlled stiffness, corrugated or segmented designs, reinforced elastomers, flexible composite tubes in low‑modulus membranes, and deployable structures that avoid internal stresses during large area changes. Anisotropic, variable‑stiffness structures are shown to enable shape change and modest area increase on aircraft wings.

Abstract

Abstract A review of morphing concepts with a strong focus on morphing skins is presented. Morphing technology on aircraft has found increased interest over the last decade because it is likely to enhance performance and efficiency over a wider range of flight conditions. For example, a radical change in configuration, i.e. wing geometry in flight may improve overall flight performance when cruise and dash are important considerations. Although many morphing aircraft concepts have been elaborated only a few deal with the problems relating to a smooth and continuous cover that simultaneously deforms and carries loads. It is found that anisotropic and variable stiffness structures offer potential for shape change and small area increase on aircraft wings. Concepts herein focus on those structures where primary loads are transmitted in the spanwise direction and a morphing function is achieved via chordwise flexibility. To meet desirable shape changes, stiffnesses can either be tailored or actively controlled to guarantee flexibility in the chordwise (or spanwise) direction with tailored actuation forces. Hence, corrugated structures, segmented structures, reinforced elastomers or flexible matrix composite tubes embedded in a low modulus membrane are all possible structures for morphing skins. For large wing area changes a particularly attractive solution could adopt deployable structures as no internal stresses are generated when their surface area is increased.