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Steady state nonlinear rotordynamics and modeling of magnetic bearings.

机译：稳态非线性转子动力学和电磁轴承建模。

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摘要

An active magnetic bearing is an electro-mechanical system that has no friction and for which the bearing stiffness and damping can be changed by varying the feedback controller's gains. They are used for compressors, turbines, vacuum pumps, flywheels, and are being developed for artificial hearts (pumps). While the currently available magnetic bearing systems have proven to be quite reliable, confidence on this new technology may be improved through developing simple models for bearing nonlinearities and studying their theoretical effects on steady state rotordynamics.; The radial active magnetic bearing considered has four pole-pairs and uses a linear current feedback control. The controller's proportional gains that result in either hardening or softening spring characteristics are obtained. A one-dimensional model of magnetic flux is developed to predict bearing force coupling of rotor motion in two perpendicular directions. The effects of this geometric coupling on linearized bearing force coefficients are determined.; The forced response of a two-degrees-of-freedom rigid rotor in one magnetic bearing for one-frequency harmonic excitation is studied. The parameters i.e. rotor unbalance eccentricity, speed, gravity load, and bearing geometric coupling are investigated to find regimes of nonlinear behavior such as jumps, bifurcation from harmonic to subharmonic or quasiperiodic motion. The nonlinear dynamics is demonstrated using frequency response curves, bifurcation diagrams, Poincare maps, and rotor orbits. Stable periodic and quasiperiodic motions are obtained using numerical integration, while coexisting stable and unstable periodic motions are obtained using the semi-analytical trigonometric collocation method. The periodic motion's local stability and bifurcation behavior are obtained using Floquet theory.; A simple piecewise linear model of magnetic material's flux saturation is obtained. Then, the effects of flux saturation on rotordynamics are investigated. Finally, the effects of bearing nonlinearities on the dynamics of a simple flexible rotor are determined.
机译：有源电磁轴承是一种机电系统，没有摩擦，并且可以通过改变反馈控制器的增益来改变轴承的刚度和阻尼。它们用于压缩机，涡轮机，真空泵，飞轮，并且正在开发用于人造心脏（泵）。虽然目前可用的电磁轴承系统已被证明是非常可靠的，但通过开发轴承非线性的简单模型并研究其对稳态转子动力学的理论影响，可以提高对这项新技术的信心。所考虑的径向有源电磁轴承具有四个极对，并使用线性电流反馈控制。获得了导致弹簧特性变硬或变软的控制器比例增益。建立了磁通量的一维模型来预测转子运动在两个垂直方向上的轴承力耦合。确定这种几何耦合对线性轴承力系数的影响。研究了一个电磁轴承中的两自由度刚性转子对单频谐波激励的强迫响应。研究了转子不平衡偏心率，速度，重力载荷和轴承几何耦合等参数，以发现非线性行为的状态，例如跳跃，从谐波到次谐波或准周期运动的分叉。使用频率响应曲线，分叉图，庞加莱图和转子轨道来演示非线性动力学。使用数值积分可以获得稳定的周期和准周期运动，而使用半解析三角搭配法可以获得稳定的和不稳定的周期运动。利用Floquet理论获得了周期运动的局部稳定性和分叉行为。获得了磁性材料通量饱和度的简单分段线性模型。然后，研究了磁通饱和度对转子动力学的影响。最后，确定了轴承非线性对简单柔性转子动力学的影响。

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  • 作者

    Chinta, Muralidhar.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 138 p.
  • 总页数 138
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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