Experimental Characterization of a Small-Scale Tailboom with Fluidic Flexible Matrix Composite Tubes

Rotorcraft tailbooms vibrate due to excitation from the rotors, separated flow behind the rotor hub, vehicle maneuvers, and wind gusts. They also typically have low inherent structural damping. This vibration leads to driveline component wear, structural fatigue, and passenger discomfort. Fluidic Flexible Matrix Composite (F2MC) tubes, a new class of passive vibration treatments, are attached to a representative tailboom structure and experimentally tested. Each F2MC tube consists of a stainless steel mesh surrounding a rubber tube. The mesh and tube are independently fastened to end fittings that mechanically connect and fluidically seal the F2MC tubes, respectively. Two tubes are mounted to the top and bottom of the tailboom and interconnected with a fluidic circuit that can be pressurized. Tests are performed to measure the fluid volume pumped by the F2MC tubes when the tailboom bends, and the tailboom displacement in response to F2MC tube pressurization. Experimental results demonstrate that the F2MC tubes can actuate tailboom bending and pump fluid. The actuation and fluid pumping results agree well with theoretical predictions. Numerical simulations, based on a previously developed model, have indicated potential for F2MC tubes to provide an efficient means of introducing useful levels of damping into tailboom structures. Characterization of the dynamic performance is ongoing.