By Army News Service on Thursday, June 13th, 2013
Army Researchers Chase Helicopter Performance Gains
A new study by Army researchers looks at inserting carbon nanotubes into the structural design of helicopter rotor blades to enhance performance.
The U.S. Army Research, Development and Engineering Command’s research laboratory hopes this approach could lead on to the design and fabrication of a better generation of rotor blades and stuck wings.
Bryan Glaz, Ph.D., Jaret Riddick, Ph.D., and Ed Habtour, research engineers from the U.S. Army Research Laboratory Vehicle Technology Directorate, lead this effort.
Glaz and a team of structural, mechanical and aerospace engineers are embedding carbon nanotubes contained in the composite matrix, resin material inside the blade, and in specific locations like near the hub, which he said “gives more bang for the buck.”
“Especially in conflicts like Afghanistan, it really highlighted the deficiencies of the DOD current fleet when it comes to payload capacity, speeds in supporting the warfighter and a major thing for the dept of Defense was the upkeep and value,” Glaz said. “They can’t be sitting in a maintenance bay because if they’re in a maintenance bay, they’re not on the market supporting the warfighter.”
Rotor structural dynamics can also be inherently unstable. Structural design and the aeromechanics of rotorcraft flight can limit forward flight and maneuver capabilities and potentially end in 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, Glaz said. Blades with good stability characteristics are inclined to transmit high vibratory loads to the aircraft, and the high vibratory quite a lot of rotorcraft are an important source of maintenance, repair and logistics burden related to the DOD vertical-lift fleet.
The reverse could also be true — blade designs with to low vibration are inclined to have structural dynamic stability issues that have a tendency to restrict the performance of the aircraft. This trade-off prevents the event of next-generation radical design concepts with substantially improved payload, speed, range and value.
“Our goal is to eliminate the trade-off,” Glaz said. “We want to manage to design blades that transmit low loads yet still have good stability characteristics.”
With the carbon nanotubes inside and inherent to that structure, researchers expect to enrich energy dissipation through friction on the nanotube-matrix interface and improve damping.
“We believe this improvement in damping will be exploited to so drastically improve stability without adding weight or mechanical complexity that rotorcraft designs never considered possible may become reality,” Glaz said.
Army researchers turned to recent scientific publications that indicate that carbon nanotubes can effectively dissipate energy for small scale samples. They’re venturing into uncharted research territory by investigating how much of the energy dissipation mechanism is also achieved when the carbon nanotubes are used to damp dynamic modes of tangible structures rather than small laboratory samples.
These components will be such as existing structures within the sense that the composite structures would still include a matrix with fiber reinforcement.
“In our case though, the matrix will be different because it would have carbon nanotubes inserted throughout,” Glaz said. “The nanotube enhanced matrix would supply the damping while fibers would still be used for strength and stiffness of the structure.”
In the longer term, a better-generation fleet will carry greater payloads and fly unimagined speeds with very low maintenance considerations, researchers said.
ARMY RESEARCH LABORATORY
The Army Research Laboratory is a part of the U.S. Army Research, Development and Engineering Command, or RDECOM, which has the mission to develop technology and engineering solutions for America’s Soldiers.
RDECOM is an immense subordinate command of the U.S. Army Materiel Command. AMC is the Army’s premier provider of materiel readiness — technology, acquisition support, materiel development, logistics power projection, and sustainment — to the whole force, around the spectrum of joint military operations. If a Soldier shoots it, drives it, flies it, wears it, eats it or communicates with it, AMC provides it.
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