Numerical modeling and analysis of a helicopter rotor blade with an active twist concept

During flight, helicopter rotor blades generate significant vibrations and noise due to aerodynamic loads. These effects limit maximum flight speed, increase operating costs, and reduce the fatigue life of structural members. The use of active control systems for helicopter rotor blades is a current scientific trend of research into noise and vibration reduction. Several methods exist for actively controlling helicopter rotor blades. One control strategy applied to suppress vibrations is Higher Harmonic Control (HHC) and Individual Blade Control (IBC). Currently, several methods of helicopter blade control are being researched with the development of piezoelectric fibres: Active Trailing Edge (ATE) and Active Twist (AT).

Active Twist is based on the fact that the actuator control elements can be located on the blade's load-bearing skin surface. The orientation of the piezoelectric fibres in the piezoelectric actuator on the top and bottom surfaces of the skin is ±45°, resulting in dynamic blade twisting when the piezoelectric actuators are activated. Thus, Active Twist can be integrated into the existing rotor blades without significant design changes.

In the present work, an analysis of a numerical study of a helicopter blade with the piezoelectric actuators integrated into the skin of the main rotor blade was performed. The results of static blade twisting as a function of the piezoelectric actuator chord-wise length are presented. Additionally, the effect of changing the geometry of the blade's cross-section on the twist angle was examined. The influence of piezoelectric actuators and changing the geometry of the blade's cross-section on the stiffness characteristics of the helicopter blade are demonstrated.