Jeffcott裂纹转子动力特性的研究

A STUDY ON THE DYNAMICS OF A CRACKED JEFFCOTT ROTOR

本文采用适当的裂纹开闭模型 ,导出了固定坐标系中裂纹轴的刚度矩阵 ,建立了水平Jeffcott裂纹转子的振动微分方程 ,并对其进行了仿真计算。数值仿真表明 :裂纹转子的响应中出现 2x、3x等倍频分量 ,并产生分数次共振现象。在超临界转速区 ,倍频分量很小 ,但在响应的相频特性图中 2x、3x处相位变化很大。参数 β和 e主要影响 1x谐波分量 ,对 2x、3x等倍频分量影响很小。由于裂纹的存在 ,转子轨迹的中心也发生偏移。在临界转速附近 ,转子运行过程中裂纹处于常开或常闭状态。一般情况 ,当转子的偏心 e小于 1时 ,裂纹在转子运行过程中总是时开时闭的。这些结论将有助于转子裂纹故障的监测和诊断。

The dynamic behavior of a horizontal cracked Jeffcott rotor is investigated in the paper. With the influence of whirl speed taken into account, the flexural stiffness matrix of the cracked shaft is derived. The equations of motion of the cracked rotor are derived and its dynamical behaviors are analyzed. Numerical analysis demonstrates that the responses of the vibration contain 2x,3x···exponents, reaching its maximum value when Ω = 1/2,1/3···resp components of high frequency almost disappear when the rotor runs in the supercritical region, but their phases change violently. β and e over-bar influence mainly 1X component. The center of the motion orbit of the rotor changes because of the existence of crack. The crack keeps open or close when the rotor runs near the critical speed. Otherwise, it opens and closes by turns if e over-bar is less than 1.