Compliant Frame: A New Paradigm to Enable Reconfigurable Aircraft Structures.

摘要

Reconfigurable ('morphing') aircraft offer the potential for efficient flight over a large range of airspeeds. The structural concept addressed herein is a tendon-actuated cellular compliant frame, with a flexible skin. 3-D cellular structures can perform well, but the need for active tendons to also carry passive lift loads limits their feasibility at larger scales. 2-D cellular structures can significantly change wing area and span, with lower actuation forces, and a system of parallel actuators is significantly lighter than a single actuator, especially at higher gross weights. Composite skins with cellular cores and flexible face sheets show promise for low-force actuation with reasonable lateral stiffness, while contact-aided cores offer additional benefits, including stress relief and increased lateral stiffness. Finally, while the potential benefits of morphing increase with aircraft gross weight, structural morphing capability decreases; this is accompanied by increasing structural and actuation weight fractions. This suggests that, for a given structural paradigm, there is a gross weight at which smooth morphing is most advantageous and practical. Continued research is needed to address the many challenges that remain before the promise of smoothly morphing aircraft can be realized.