Development of Mach Scale Rotors with Tailored Composite Coupling for Vibration Reduction

This paper presents the design, structural and aeroelastic analyses, fabrication, and structural tests of Mach-scale articulated composite rotors with tailored flap-bending/torsion couplings for vibration reduction. The rotor design was nominally based on the UH-60 Black Hawk rotor. A new fabrication process was developed to manufacture Mach-scale composite tailored blade. Five sets of Mach-scale composite tailored rotors were successfully fabricated in-house, including a baseline rotor without coupling, two rotors with uniform spanwise flap-bending/torsion couplings, and two rotors with spanwise segmented flap-bending/torsion couplings. Bench-top and nonrotating dynamic tests were performed to verify the structural analysis of these composite tailored blades. The measured results correlated well with predictions. Comprehensive aeroelastic analysis (using University of Maryland Advanced Rotorcraft Code) of these Mach-scale composite tailored rotors indicated that blade elastic flap-bending/ torsion couplings can significantly impact rotor vibration characteristics. It was shown that spanwise segmented flapbending/torsion couplings can provide larger rotor vibration reduction than uniform spanwise couplings.