Fatigue Characteristic Analysis Of Gyroplane Rotor Blade

Rotor blades are the main lift components of the gyroplane. During the flight of the gyroplane, the long and thin blades produce a continuous aeroelastic response under periodic alternating aerodynamic loads. The resulting problems of structure vibration and fatigue directly affect the use of the gyroplane's comfort and safety. Combining with the development requirements of a certain type of the gyroplane, the calculation of blade vibration load and the method of fatigue life prediction are studied and have the important engineering application value.In vibration load calculation aspect, based on the Hamilton's principle and Hodges moderated deflection rotating beam theory, the fully flap-lag-torsion coupled equations of motion are established. The equations of motion are then discretized by the beam element with 2 nodes and 12 degrees of freedom, and the equations of spatial finite element form are obtained. Based on the prescribed airloads, the Newmark method is used to calculate the dynamic response of the blade and the improved force integral method solves the vibration load of the blade. By comparing with the reference of dynamic response and vibration load, verify the correctness of the methods.In fatigue life prediction aspect, the load signal compression, cyclic counting and complex stress synthesis are studied, and a set of new "three point method" of invalid amplitude cycles is established by classifying the data signals. On this basis, the fatigue life of the gyroplane rotor blade is calculated and analyzed by the Miner's fatigue model combining the gyroplane application requirements and fatigue life curve of blade material.