The identification equations for a rotor-bearing system equipped with a hydrodynamicbearing are formulated. The angles where the thrust bearing acts need not be measured. TheBFGS method combined with a hierarchical procedure is used to solve the identificationequations. The applicability of the frequency-domain method in the identi"cation of all theoil-film dynamic coefficients of journal bearings and thrust bearing is confirmed bynumerical simulation. It is also shown that the method is of high anti-noise ability.

The non-linear dynamics of a rigid rotor levitated by active magnetic bearings isinvestigated. The vibrations in the horizontal and vertical directions are analyzed on thecenter manifold near the double-zero degenerate point by using normal-form method. Theresulting normal forms in the horizontal and vertical directions are di!erent due to the e!ectof rotor weight. It is shown that the vibratory behavior in the vertical direction can bereduced on the center manifold to the Bogdanov}Takens form. For the autonomous case,there exist saddle-node bifurcation and Hopf bifurcation for local analysis, anda saddle-connection bifurcation for global analysis. For non-autonomous case, theMelnikov technique is used to determine the critical parameter at which the homoclinicorbits intersect transversally. For the vibrations in the horizontal direction, the essentialnon-linear terms of the truncated normal form are third order. The behaviors of zerosolutions are given. Finally, numerical simulations are performed to verify the analyticalpredictions.

The misalignment of a gear coupling in a multirotor system is an important problem; itcan cause various faults. In the present work the non-linear coupled lateral torsionalvibration model of rotor-bearing-gear coupling system is developed based on theengagement conditions of gear couplings. Theoretical analysis shows that the forces andmoments acting on gear couplings due to the initial misalignment are from the inertia forcesof the sleeve and the internal damping between the meshing teeth, and depend on themisalignment, internal damping, the rotating speed, and the structural parameters of thegear coupling. Numerical analysis of the signature of vibration reveals that the even-integermultiples of the rotating speed of lateral vibration and the odd-integer multiples of thetorsional vibration occur in the misaligned system, and the integer multiples of vibration areapparent around the gear coupling.

弹性箔片空气动压轴承被广泛应用于各种透平机械中，然而由于其结构的复杂性，对于这类轴承的建模、静动态性能计算以及相应转子系统动力学分析等理论研究一直处在严重滞后于实验研究的被动局面。通过引入柔性箔片的静、动变形以及联立求解气体润滑Reynolds方程和弹性箔片的静、动变形方程,给出了弹性箔片空气动压轴承的完全气弹润滑耦合解，完全气弹润滑解不仅适用于箔片轴承的静态性能分析，同样也适用于动态刚度和阻尼的计算，从而为弹性箔片空气动压轴承静、动态性能分析和相应转子系统动力学行为预测提供了系统的理论与分析方法。