Structural Design Of Variable Twist Rotor Blade Based On Macro Fiber Composite (MFC)

Variable-twist control of rotor blades using piezoelectric materials is one of the effective active control methods for reducing vibration and noise and improving rotor performance of helicopters.The macro fiber piezoelectric composite(MFC)is the most ideal intelligent material at present.Therefore,it is of great significance and practical value to study the structure design of variable twist rotor blade based on MFC.(1)Firstly,the working principle of MFC is analyzed in this paper.According to the constitutive equation of MFC,the driving mechanism of d33-MFC and d31-MFC as actuators is discussed theoretically,which provides a theoretical basis for selecting d33-MFC with better torsional driving performance.The validity of the finite element modeling of piezoelectric composite material by thermal-elastic analogy method is verified by a specific example.And the cantilever beam with MFC attached is analyzed,the results show that the driving voltage,the direction angle of piezoelectric fibers,the laying position and laying area of d33-MFC material on the cantilever beam,and the material of the cantilever beam all have an influence on the twist angle of the cantilever beam.(2)Us ing NACA0012 airfoil,a variable twist rotor blade structure based on MFC was preliminarily des igned.The dynamic analys is of the designed model blade is carried out,and the resonance diagram of the model blade is drawn,it is proved that the resonance of the model blade will not occur at the working speed.The effect of rotor speed on blade twist angle is also studied,It shows with the increase of rotational speed,the torsion angle decreases,but the amplitude changes slightly.Finally,in order to verify the feasibility of MFC-based variable-twist blade structure in this paper,an experimental system is designed to study the d33-MFC driving model blade twist.