Structural Dynamics and Smart Rotor Blades for Helicopters

A major focus of Professor Afagh’s research program in the recent years has been the development of a mathematical model for a helicopter smart rotor blade with a high degree of fidelity. The model will be used to investigate the possibility of attenuating undesirable dynamic responses associated with operation of helicopter rotor blades. A continuous model of a smart blade has already been developed in the previous phase of this research program. The model represents a thin wall, closed cross-section, active composite beam that incorporates macro piezoelectric fibres as actuators which are integrated structurally into a carbon fibre composite to form Macro Fibre Composites (MFC).

The current model of smart rotor blades does not account for the effect of initial twist that could be present in modern helicopter rotor blades. This capability will be integrated into the existing mathematical model. Moreover, the idea of using open cross-section thin-wall adaptive beams in various terrestrial and aerospace structures, e.g., as adaptive thin-wall open cross-section spars in rotor blades, is also being proposed as a novel concept. The governing equations to determine the cross–sectional stiffnesses of open-section, thin wall, active MFC beams has been the subject of most recent developments under the supervision of Professor Afagh. Another objective of the current ongoing research is to investigate the effectiveness of smart MFC rotor blades to control blade sailing phenomenon (BSP). Blade sailing refers to large elastic deformations of blades that can occur at low rpms of rotors on shipboard helicopters, especially under the combined effect of high wind-induced aerodynamic loads and severe ship deck motion at high seas. As the result, the blades may come into contact with the fuselage or tailboom of the helicopter causing substantial airframe damage and comprising the safety of flight crew and the ship deck personnel.

Model of an articulated rotor blade configuration. All joints are assumed to be simple revolute joints and articulation links to be rigid.

Time histories of: (I) The experimental/theoretical flap hinge angle, (II) The Experimental/Theoretical strain at 40% blade length station of the drop test/droop stop impact from 9.7°.

Development of a 1/12th Froude scaled flap articulated rotor system.