Analysis and Testing of Rotating Blade Natural Frequency

Reasonable allocation of the natural frequencies of a blade can help to avoid resonance or excessive vibration within the helicopter's working speed range, thus reducing and controlling the vibration level. For composite blades, the motion equation of the blade was deduced using the Hamilton principle to obtain the natural frequency and natural vibration mode of the blade. Full-scale blade natural frequency tests were carried out on the rotor testing device, and the analysis results were in good agreement with the test results. Based on this, the influence of rotor stiffness parameters on the natural frequency of the blade was studied. The results show that the first lag frequency of the blade increases with the increase of the elastic bearing and blade lag stiffness, which has little influence on the flap frequencies and torsional frequency.