Testing and Analysis of Shape-memory Polymers for Morphing Aircraft Skin Application

Morphing aircraft have the potential to possess a variety of advantages over current static aircraft, such as improved maneuverability, increased speed and better fuel efficiency. This thesis focuses on testing the feasibility of a shape-memory polymer to function as the skin of a morphing aircraft undergoing the wing-sweep method of wing shape-change. A review of literature is presented, giving a brief history of shape-memory polymers, an overview of current significant shape-memory polymer application, an overview of current morphing aircraft in morphing application and an overview of the current methods to activate shape-memory polymers. Analytical and finite element models are created to predict out-of-plane deformations caused by aerodynamic loads on an independently functioning sub-section of a tile array that would comprise the skin of a morphing aircraft. Five generations of a shape-memory polymer tile sub-section with embedded fibers are described and subsequently tested to confirm analytical and finite element models. Alternate shape-memory polymer tile sub-sections are created to specifically address the problem of buckling as the tile experiences shear-induced shape-change mimicking that seen in a morphing aircraft. Bi-axial pre-strains are induced on the alternate tile sub-sections to successfully cure the buckling problem. Finite element modeling, thermal analytical analysis and screw-driven load frame machine data are used to calculate the power required to induce shape-change as well as sufficiently heat the tile sub-section via its embedded wires. Power requirements, experimental results and modeling results are discussed in terms of real-world feasibility. Finally, suggestions are made for future work on a similar topic.

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