Analysis Of Morphing Skin Structure Based On Shape Memory Polymer Composite Tube

The performances of the aerospace systems can be influenced by designapproaches and innovation of novel materials. New solutions in morphing structuresmay lead to a decrease in operating costs by reducing weight. In an integrated flightcycle with continuously varied flight parameters, morphing aircrafts could adapt to theoutside flight environment through changing their wing shapes. They are able to offergreat potential for performance improvements in comparison with traditional aircrafts.Morphing skin is one of the key techniques to realizing morphing aircraft. In order torealize the great changes of chord length, span length, sweepback angle and wing area,the skin must be able to withstand large enough deformation. Moreover, the skin shouldhave enough out-of-plane stiffness to maintain the aerodynamic loading during thedeformation process, at the same time the in-plane stiffness of skin should be as little aspossible to reduce the energy requirements.Shape memory polymer (SMP) is an emerging class of active polymers that havedual-shape capability. When exposed to specific external stimulus, such as heat,magnetic and electricity, they can change their shape from the temporary state to theoriginal state. In this study, a kind of shape memory polymer composite (SMPC) tubecomposed of carbon fiber and SMP is designed, manufactured and investigated.Significant stiffness variation for the SMPC tube can be obtained through changing itsenvironment temperature.Based on the SMPC tube, a kind of morphing skin is designed. By using finiteelement software, it is analyzed in two states (cold state and heated state) with the sameuniform load. The relationship between geometry and deflection of morphing skin andthe deflection ratio under two states could be obtained. Since it is difficult to heat theSMP material and its composite with traditional method, the temperature distribution ofSMPC tube that heated by the hot fluid is obtained through the finite element analysis(FEA).In order to investigate the basic elastic properties of the morphing skin, the Rule ofMixture is used to predict the effective engineering modulus and modulus ratio withdifferent matrix volume fractions. The tensile test is conducted on the skin in two states (cold state and heated state) to validate the accuracy of the theoretical method. Acorresponding heating system is designed and manufactured to provide heat for themorphing skin. Based on the heating system, the deflection is investigated through thestress-bearing capability test. Moreover, the infrared test is carried on the morphing skinto show the temperature distribution during the heating process.The influence of design parameters of morphing skin is discussed in this study,higher sensitive parameters are obtained from the analysis by ISIGHT software. Then,the quality and maximum deflection of the morphing skin structure are optimized bygenetic algorithms with the same software and the most suitable design parameters forboth objectives are obtained. At last, a laminated structure is designed based on thesingle-layer morphing skin. With specific ply design, this laminated structure couldachieve different moduli by changing the heating state of different layers.