Abstract
In certain rotor systems, bending-torsion coupled resonance occurs when the rotational speed f_r is equal to the sum/difference of the bending natural frequency f_b and the torsional natural frequency f_θ. This coupling effect is due to an unbalance of the rotor. In order to clarify these phenomenon, we introduced the equation of motion for the coupled system of torsional/bending vibration and the external damping to recover instability at f_r=f_θ+f_b. We experimentally confirmed the occurrence of bending-torsion coupled resonance at f_r=f_θ±f_b by adding bending excitation of f_b.
