In the present investigation, the helicopter blade is modelled as a rotating beam with two degrees of freedom, namely the elastic flatwise bending and torsion. A mathematical model in the frequency domain is developed, incorporating the incompressible unsteady aerodynamic loads associated with helicopters in forward flight. The effects of dynamic adaptation of the root boundary conditions on the beam aeroelastic response are studied. The results suggest that it is possible to control the local dynamic response at particular sections of the blade by varying the frequency and relative phase of the control signal.

Canadian Aeronautics and Space Journal
Department of Mechanical and Aerospace Engineering

Nitzsche, F. (2001). Aeroelastic analysis of a helicopter rotor blade with active impedance control at the root. Canadian Aeronautics and Space Journal, 47(1), 7–16.