Abstract A floating-ring bearing (FRB) is composed of a journal, a floating ring and a housing which are separated by two thin oil films. This system is inherently nonlinear and if it is lightly loaded or operated at high speeds, it is prone to the fluid-induced instability. The threshold speed for the instability of a journal bearing with one oil film can be estimated using linearized forces acting in the film. However, the linear analysis of FRB might be problematic because results of such an analysis are usually difficult to interpret. Nevertheless, the linear analysis can provide some fundamental insights into system behaviour. This work aims to evaluate in detail the use of linear theory in the stability analysis of rotating systems supported on FRBs. Several approaches for the linearization of the forces acting in FRB are proposed and analysed. The results are visualized in the form of a holistic Campbell diagram which together depicts natural frequencies, whirl frequencies, modal damping and precession of mode shapes. Moreover, it is demonstrated that the holistic Campbell diagram can be used to interpret – and to some extent, also to predict – results of nonlinear analysis.

中文翻译：

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浮动环轴承各种线性化方法在涡轮增压器非线性动力学中的预测能力

摘要 浮环轴承（FRB）由轴颈、浮环和轴承座组成，并由两层薄油膜隔开。该系统本质上是非线性的，如果它是轻载或高速运行，则容易出现流体引起的不稳定性。带有一层油膜的轴颈轴承不稳定的阈值速度可以使用作用在油膜中的线性化力来估计。然而，FRB 的线性分析可能存在问题，因为这种分析的结果通常难以解释。然而，线性分析可以提供对系统行为的一些基本见解。这项工作旨在详细评估线性理论在 FRB 支撑的旋转系统的稳定性分析中的应用。提出并分析了几种将作用在 FRB 中的力线性化的方法。结果以整体坎贝尔图的形式可视化，该图一起描绘了固有频率、旋转频率、模态阻尼和模态形状的进动。此外，还证明了整体坎贝尔图可用于解释——在某种程度上，还可以预测——非线性分析的结果。