幾何学的非線形ばね特性をもつ連続偏平軸の強制振動 : 主危険速度と二次的危険速度付近(機械力学,計測,自動制御)

概要

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Forced oscillations in the vicinities of the major critical speed and the secondary critical speed of a continuous asymmetrical rotor with the geometric nonlinearity are discussed. When both ends of the rotor are supported by self-aligning double-row ball bearings, this geometric nonlinearity appears due to the stiffening effect in elongation of the shaft if the movements of the bearings in the longitudinal direction are restricted. The nonlinearity is symmetric when the rotor is supported vertically, and is asymmetric when it is supported horizontally. Because the rotor is slender, the natural frequency of a forward whirling mode p_<fn> and that of a backward whirling mode p_<bn> have the relation of internal resonance p_<fn>: p_<bn>=1:(-1). Due to the influences of the internal resonance, the complicated resonance phenomena such as Hopf bifurcation, an almost periodic motion, the appearance new branches and the disappernance of unstable region, occur. These phenomena were clarified theoretically and experimentally. The influences of the nonlinearity, the unbalance, the damping, and a lateral force on the vibration characteristics are also examined.
2001-12-25