开裂纹转子的动力分析

A Study of the Vibration of a Rotor with an Opening Crack

以水平放置Jeffcott裂纹转子为研究对象 ,建立了弯扭耦合振动的非线性运动微分方程 ,并用数值方法分析了纯弯曲振动与弯扭耦合振动情况下的转子的动力响应。结果表明 :弯扭耦合振动是通过不平衡量来实现的 ,当不平衡偏心很小时可以不考虑扭转振动的影响。当不平衡偏心较大时 ,扭转对弯曲振动的影响主要体现在高转速部分 ,且随裂纹深度的增加 ,影响的转速下限就会越低 ,所以当裂纹较浅、转速较慢时可不考虑扭转的影响 ,但当裂纹较深、转速较快时 ,扭转对弯曲振动有明显的影响 ,使频谱图和轴心轨迹都发生较大的变化 ,且对转速的变化极为敏感。

The bending torsional coupled vibration of a level Jeffcott rotor containing a transverse crack is investigated in this paper. The nonlinear differential equation of bending torsional vibration of a cracked rotor is derived, and the dynamical behaviors of the cracked rotor are analyzed comparing with bending vibration of the rotor. Numerical analysis demonstrates that: The coupled vibration is caused by the eccentricity ε, the torsional vibration can be ignored if the ε is very small. But if the ε is great, the running orbit of the cracked rotor and the spectral response are influenced greatly when the rate of rotative Ω velocity is higher, and are sensitive to the change of Ω. The deeper the crack is, the lower the influenced Ω is. So, when the cracked rotor is on a high rotative velocity and with a deep crack, the torsional vibration must be considered in the fault diagnosis for rotation machinery.