Analysis and vibration control of a helicopter rotor blade

A study of helicopter blade vibration control is presented in this work. The blade is modelled by the finite element method and it is considered as a rotating beam undergoing the coupling motions of flapping, lead-lagging, axial stretching and torsion. The blade model also considers a pretwist angle, offset between mass and elastic axes and isotropic material. The finite element matrices are obtained by energy methods and a linearization procedure is applied to the resulting expressions. The linearized aerodynamic loading is calculated for hover and the state-space approach is used to design the control system. The eigenstructure assignment by output feedback is used in the blade reduced model resulting from the application of the expansion method by partial fractions. The simulations for open and closed-loop systems are presented, having exhibited good response qualities, and they show that output feedback is a good alternative for helicopter vibration attenuation. >