The material damping of rotors causes instability by introducing tangential force to whirl orbit. Literature shows that the improvement of stability range is achieved using fibre-reinforced composites or layered rotors which are light yet strong and exhibit better damping properties. In this study, a multi-layered viscoelastic propeller shaft mounted on three journal bearings is considered. Higher order finite-element model is developed after utilizing operator-based constitutive relationship, which includes various asymmetries from several sources like gyroscopic effect, internal damping, and journal bearing support. A large number of states of the higher order model, as well as the presence of asymmetry, make the system complicated for post-processing. Modified system equivalent reduction expansion process (SEREP) is applied for model reduction that uses both right and left eigenvectors of the original propeller-shaft system. Different numerical results are compared to test the effectiveness of reduced model. Though SEREP is found in the literature, its application over most realistic and higher order asymmetric system is completely new.

中文翻译：

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考虑各种不对称性的基于SEREP的高阶粘弹性传动轴简化模型

转子的材料阻尼通过将切向力引入旋转轨道而导致不稳定。文献表明，使用纤维增强复合材料或分层转子可以提高稳定性范围，这些材料既轻又坚固，具有更好的阻尼性能。在这项研究中，考虑了安装在三个轴颈轴承上的多层粘弹性传动轴。高阶有限元模型是在利用基于算子的本构关系后开发的，其中包括来自多个来源的各种不对称性，如陀螺效应、内部阻尼和轴颈轴承支撑。高阶模型的大量状态，以及不对称性的存在，使系统的后处理变得复杂。改进的系统等效缩减展开过程 (SEREP) 应用于模型缩减，该模型缩减同时使用原始螺旋桨轴系统的左右特征向量。比较不同的数值结果以检验简化模型的有效性。虽然 SEREP 是在文献中找到的，但它在大多数现实和高阶非对称系统上的应用是全新的。