Variable stiffness corrugated composite structure with shape memory polymer for morphing skin applications

Abstract

This work presents a variable stiffness corrugated structure based on a Shape Memory Polymer (SMP) composite with corrugated laminates as reinforcement that shows smooth aerodynamic surface, extreme mechanical anisotropy and variable stiffness for potential morphing skin applications. The smart composite corrugated structure shows a low in-plane stiffness to minimize the actuation energy, but also possess high out-of-plane stiffness to transfer the aerodynamic pressure load. The skin provides an external smooth aerodynamic surface because of the one-sided filling with the SMP. Due to variable stiffness of the shape memory polymer the morphing skin exhibits a variable stiffness with a change of temperature, which can help the skin adjust its stiffness according different service environments and also lock the temporary shape without external force. Analytical models related to the transverse and bending stiffness are derived and validated using Finite Element techniques. The stiffness of the morphing skin is further investigated by performing a parametric analysis against the geometry of the corrugation and various sets of SMP fillers. The theoretical and numerical models show a good agreement and demonstrate the potential of this morphing skin concept for morphing aircraft applications. We also perform a feasibility study of the use of this morphing skin in a variable camber morphing wing baseline. The results show that the morphing skin concept exhibits sufficient bending stiffness to withstand the aerodynamic load at low speed (less than 0.3 Ma), while demonstrating a large transverse stiffness variation (up to 191 times) that helps to create a maximum mechanical efficiency of the structure under varying external conditions.

Electro-active Variable-Stiffness Corrugated Structure Based on Shape-Memory Polymer Composite

“…It was flexible in the transverse direction and stiff in the longitudinal direction. The anisotropic mechanical property can be evaluated by the relative transverse stiffness and section bending stiffness [51]. The relative transverse stiffness and section bending stiffness of the corrugated sheet presented in this work could reach 0.0018 and 558.28, respectively, which shows good mechanical anisotropy.…”

Free-edge effects of corrugated laminates

“…Bai et al [27] suggest a flexible-skin design for morphing applications where two corrugated laminates are bonded together so that a symmetric structure results. Henry et al [28] and Gong et al [29] consider a morphing-wing concept with distributed piezoelectric actuation and a corrugated flexible-skin section. Thurnherr et al [30] investigated the static response to homogeneous pressure of highly anisotropic corrugated sheets.…”

Development of an adaptive morphing wing based on fiber-reinforced plastics and shape memory alloys

“…The most common applications for morphing wings in the aeronautics industry are the smart trailing edge, smart winglet, smart slat, and smart drop nose [4]. Actuated morphing wings are also used in bat-like micro aerial vehicles [5] or as leading edges, engine inlets, helicopter rotor blades, ships, wind turbines, hydrodynamic surfaces, and automobiles [6,7].…”