Design and dynamic analysis of a spanwise morphing wing for Mars exploration

Abstract

The application of spanwise morphing wings makes it possible to transport and launch large-size Mars exploration UAVs. This article proposes a modular variable spanwise morphing wing for high-aspect-ratio aircrafts, and analyses the characteristics of the morphing wing by theoretical analysis, numerical simulation and experimental verification. The novel spanwise morphing wing is based on the Sarrus-inspired deployable structure, which can increase the wing's lift by changing the spanwise length. The pre-strain torsion springs are assembled to provide the initial driving moment of the morphing mechanism. A regular triangle cross section is selected by evaluating the bending and torsional stiffness, and deployable triangular prism mechanisms are identified. Through releasing the pre-strain torsion springs to achieve expansion and implant Sarrus linkages along the straight motion paths. A lockable structure is designed, and the main factors affecting the self-locking property are analysed. A rigid origami skin is proposed, which maintains the airfoil's continuous smoothness after spanwise morphing. The kinematics of the spanwise morphing wing unit is developed using the Lagrange equation, and the theoretical models of morphing wings with different numbers of units are obtained. The unit numbers influence fully expanded time, and the time decreases gradually along the wingtip's direction. Finally, a one-way fluid-structure interaction analysis is performed to investigate the spanwise morphing mechanism and origami skin response under aerodynamic loads. Results show that the skeleton mechanism's maximum stress is below the material's yield strength, and the origami skin's maximum out-of-plane deformation is less than 0.5% of the wing chord, which provides a necessary theoretical basis for applying the spanwise morphing wing.