<p>Morphing adaptive wingtip technology is a new aircraft design direction which could improve the reduction of the induced drag, fuel consumption, and take-off and landing distances compared with wing configurations. We describe in this work a morphing adaptive winglet structure based on active inflatable honeycombs and Shape Memory Polymer Composite (SMPC) skins. The combination of the two materials and structural subsystems allow the winglet folded and deployment, with a morphing adaptive skin able to withstand the aerodynamic loading, also through the use of distributed pneumatic muscle fibers. The geometrical configuration and the mechanical performance of the active honeycomb under compression is modeled. The input pressure/wingtip angle relationship for the morphing wingtip system is also obtained, and verified in a specific test sample. A simulacre of morphing wingtip is fabricated and its performance showed a good agreement with the theoretical framework developed. A morphing adaptive wingtip prototype is also fabricated to demonstrate the kinematics and actuation of the concept. To figure out the influence of the wrinkle between wing and wingtip which appears when the wingtip folded, a flow field simulation was taken using FLUENT. The simulation results show that the wing with wrinkle has little difference to the unwrinkled one and even a little better in some cases. Pneumatic fiber muscles have been developed as adaptive stiffeners to adjust the bending and membrane stiffness of the shape memory polymer skin during deployment. The operational effectiveness of the stiffened SMPC plate is verified by experimental tests produced in an ad-hoc rig, and Finite Element models that provided a good agreement with the experimental trends measured. The concept described in this paper may be further evaluated for the use of small UAVs, or for other adaptive structures designs in which shape memory polymers could find their use.</p>

An Adaptive Winglet Structure Based on Active Inflatable Honeycomb and Shape Memory Polymer Composite Skin

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2021/volume/85499

ASME 2021 Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS2021)

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