Structural dynamics and smart helicopter rotor blades

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A major focus of the applicant'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. Such a 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-section, active composite beam that incorporates piezoelectric fibres as actuators that are integrated structurally into a carbon fibre composite to form Macro Fibre Composites (MFC). This proposal has two objectives: 1) the existing model of smart rotor blades does not take into account the effect of initial twist that could be present in modern helicopter rotor blades. This capability will be integrated into the existing mathematical model under the current proposal. Moreover, the idea of using open cross-section thin-wall adaptive beams in various terrestrial and aerospace structures, e.g., rotor blades with spars consisting of adaptive thin-wall open sections, is also being proposed as a novel concept. In the next phase the governing equations to determine the cross-sectional stiffnesses of open-section, thin wall, active MFC beams will also be developed. 2) Investigation of the effectiveness of smart MFC rotor blades to control Blade Sailing Phenomenon (BSP) in ship-board helicopters is the second objective of this proposal. BSP refers to large elastic deformation 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 can 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.