Natural vibration analysis of bearingless rotor blades

Natural vibration characteristics of bearingless rotor blades design were investigated by transfer matrix method, and the natural frequencies of blade vibration were calculated with a fixed or spring restrained torque tube end. Coupling of pitch/lead-lag was also considered. Parametric studies were performed to examine the effects of several model parameters on vibration natural frequencies. Some flapwise and chordwise bending mode shapes were revealed. The results indicate that pitch/lead-lag coupling of the torque tube end has little influence on natural frequencies, the pitch angle of blade has complex influence on natural frequencies, and the distance of mass center from elastic axis has slight influence on high natural frequencies.