Design, modeling, and testing of a fluidic flexible matrix composite damped absorber prototype for stiff-inplane hingeless rotorcraft blades

Fluidic Flexible Matrix Composite (F² MC) tubes have been shown to provide enhanced damping in stiff rotorcraft structures such as tailbooms. In this paper, a F² MC treatment is investigated for stiff-inplane rotors, such as those used in modern high-speed coaxial configurations. These rotor blades undergo little inplane deformation near the blade root, making traditional lag damper solutions ineffective. The F² MC damped absorber is a low weight, passive, and linear treatment capable of achieving high damping even at small strain. The coupled F² MC damped absorber is modeled for a full-scale stiff inplane rotor blade, with simulation results predicting an increase in damping from a baseline of c= 2% to c = 15.1%. The model is used to simulate and design a laboratory-scale prototype blade. The blade is experimentally tested, including measurements of tip displacement, bending strain at the root, and internal fluid pressure under impulse loadings and sinusoidal shaker excitation. Experimental results validate the model and demonstrate an increase in damping from c = 0.5% to c = 10.29%.