On advanced high-speed rotorcraft the optimal rotor blade geometry can vary considerably corresponding to variation in operating conditions. This project considers changes in blade cross-section profile, blade camber, and rotor twist. Various kinematic and actuation mechanisms, such as the use of optimized extension-twist-coupled ply layups along the blade and the use of Shape Memory Alloys for actuation, are studied. In addition to the design and implementation of the actuation mechanism, the effect of the morphing on performance improvement is studied (for example, to what degree a specific approach is beneficial in reverse flow, or is able to simultaneously improve low-speed and high-speed performance vis-à-vis a fixed geometry design). One of the sub-tasks under this project is focused on the design optimization of an extension-torsion-coupled composite main rotor blade that changes tip twist by about 8-10 deg due to change in centrifugal force as the rotor RPM changes from 100% NR to 80% NR, while considering constraints pertaining to failure and manufacturability.
