A new study by Army researchers looks at inserting carbon nanotubes into the structural design of helicopter rotor blades to improve performance. The U.S. Army Research, Development and Engineering Command's research laboratory hopes this approach could lead to the design and fabrication of the next generation of rotor blades and fixed wings.
A team of structural, mechanical and aerospace engineers is embedding carbon nanotubes inside the composite matrix, resin material throughout the blade, and in specific locations like near the hub, which "gives more bang for the buck." With the carbon nanotubes inside and inherent to that structure, researchers expect to enhance energy dissipation through friction at the nanotube-matrix interface and improve damping.
Rotor structural dynamics can be inherently unstable. Structural design and the aeromechanics of rotorcraft flight can limit forward flight and maneuver capabilities and potentially lead to catastrophic structural failures in takeoff and landing conditions.
There is a tradeoff between rotor blades designed to transmit low vibrations to the aircraft and blades designed for stability. Blades with good stability characteristics tend to transmit high vibratory loads to the aircraft, and the high vibratory loads of rotorcraft are a major source of maintenance, repair and logistics burden associated with the DOD vertical-lift fleet.
The reverse is also true -- blade designs with to low vibration tend to have structural dynamic stability issues that tend to limit the performance of the aircraft. This trade-off prevents the development of next-generation radical design concepts with substantially improved payload, speed, range and cost.
In the future, the next-generation fleet will carry greater payloads and fly unimagined speeds with very low maintenance considerations, researchers said.