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

Xiaobo Gong,Yanju Liu,Liwu Liu,Fang Xie,Jinsong Leng

doi:10.3390/polym12020387

Abstract

Shape-memory polymers (SMPs) can adjust their stiffness, lock a temporary shape, and recover the permanent shape upon an appropriate stimulus. They are applied in the field of morphing skins. This work presents a variable-stiffness corrugated sheet based on a carbon fiber felt (CFF)-reinforced epoxy-based SMP composite that shows variable stiffness and extreme mechanical anisotropy for potential morphing skin applications. The corrugated sheet exhibits a variable stiffness with a change in temperature, which can help the skin adjust its stiffness according to different service environments. The corrugated sheet can be electrically heated rapidly and homogeneously due to its high electrical conductivity and enhanced heat transfer efficiency. Its Joule-heating effect acts as an effective active stimulation of the variable stiffness and shape-memory effect. The CFF-reinforced epoxy-based SMP composite was manufactured into a corrugated shape to obtain extreme mechanical anisotropy. The corrugated sheet shows a low in-plane stiffness to minimize the actuation energy, while it also possesses high out-of-plane stiffness to transfer the aerodynamic pressure load. Its mechanical properties, electrical heating performance, and shape-memory effect were investigated using experiments. The results show that the proposed SMP composite exhibits extreme mechanical anisotropy, considerable deformation ability, and variable stiffness induced by Joule heating without an external heater.

Highlights

Morphing aircraft can adapt their aerodynamic and structural shape to extend the aeromechanic flight envelope and accomplish multi-mission profiles; this attribute is treated as an important direction for future aircraft development [1,2,3,4,5]
The mechanical dynamic mechanical properties of SMPE and were studiedThe using dynamic analyzer
TheThe investigation focused on mechanical properties, electrical heating and evaluated with experiments

Summary

Introduction

Morphing aircraft can adapt their aerodynamic and structural shape to extend the aeromechanic flight envelope and accomplish multi-mission profiles; this attribute is treated as an important direction for future aircraft development [1,2,3,4,5]. Ingenious morphing wing structures are critical to realizing the characteristics of a morphing aircraft. The morphing wing structures are complex and sophisticated systems, including morphing skins, actuators, adaptive structures, and associated mechanisms. Each component should be designed for a performance trade-off between compliance to perform the morphed shape, stiffness to withstand and transfer the aerodynamic loads, and weight to maximize payloads while minimizing the airframe weight [2]. A morphing skin should feature flexible properties to obtain large deformations and minimize driving forces, and possess high stiffness to withstand and transfer aerodynamic pressure loads. Variable-stiffness materials and structures aroused the interest of researchers to solve the contradiction between high stiffness and reversible deformability required by morphing skins [6]

Methods

Results

Conclusion