Effect of Elastic Support on the Vibration Characteristics of Rotating Thin-Walled Beams

With respect to the dynamics of the rotor system of articulated helicopters, the clamped boundary cannot accurately describe the real situation of the blade–hub connection conditions, whereas the introduction of elastic boundary conditions can more precisely determine the dynamic response of the rotor system. Moreover, to meet the requirements of light weighting, the rotor blades are simplified into thin-walled beam structures with practical engineering significance. Therefore, a coupled chord-wise, flap-wise and torsional dynamic model for elastically restrained rotating thinwalled beams is proposed, and the effects of the elastic boundary, rotation speed and pre-twist angle on the vibration characteristics of thin-walled beams are systematically analysed. The applicability of the Euler–Bernoulli and Timoshenko beam theories to rotating thin-walled beams with different wall thickness is presented for the first time. The influence law of the elastic boundary on the vibration characteristics is investigated mainly via a rotating experimental platform. The experimental results reveal that the elastic boundary significantly alters the natural frequency of the system. On the basis of the experimental data, the parameters of the boundary spring stiffness in the theoretical model are identified, confirming that the established theoretical model can simulate complex boundary conditions.