裂纹转子弯扭耦合瞬态振动影响因素研究

RESEARCH ON INFLUENTIAL FACTORS REGARDING COUPLED FLEXURAL AND TORSIONAL TRANSIENT VIBRATION OF A CRACKED ROTOR

针对两端刚性支承的Jeffcott转子 ,推导了裂纹转子的弯扭耦合振动非线性微分方程 ,通过数值仿真手段 ,分析了升速过程中弯振和扭振的瞬态特性 ,并详细探讨了加速度、裂纹减小刚度、裂纹夹角、质量偏心以及阻尼系数等因素对弯扭耦合振动瞬态特性的影响。研究表明 ,升速过程中 ,随着加速度增大 ,弯振和扭振各共振峰值减小 ,而对应转速增加。各共振峰值均随着△kη的增加而增大 ,当△kη 超过某值后 ,峰值急剧增加。β在 0 ～ 2π范围内变化时 ,各共振峰值呈现不同周期的正余弦变化。质量偏心主要影响临界峰值 ,对其它各峰值影响很小。各峰值均随阻尼系数的增加而降低 ,阻尼系数较小时 ,峰值减小率更大。

A rigid supported rotating Jeffcott rotor system with a transverse crack is considered. The nonlinear differential equations of coupled flexural and torsional vibration are established. Through numerical simulation, transient characteristics of flexural and torsional vibration are analyzed when the shaft is accelerated. Some influential factors regarding transient vibration, including acceleration magnitude, crack reduced stiffness crack angle, mass eccentricity and damping coefficient are discussed. The results show that the resonance peaks of flexural and torsional vibration will reduce in magnitude and the corresponding rotating speeds of the rotor will rise with the increase of acceleration. Mass eccentricity only influences the main critical peak and has less effect on other peaks. The peak values will decrease with the increase of damping coefficient and when the damping coefficient becomes smaller, the rate of peak value decreasing will be larger.