Abstract
The aim of this study is to show how baseplate flexibility can be included in the rotodynamic analysis in an efficient yet accurate manner. Baseplate modal information is added into the classical rotodynamic system (rotor + bearings) using a proper modal condensation method. On the one hand, the relatively complex shape of the baseplate requires 3D modelling strategies, while rotodynamic analysis is normally conducted using 1D beam elements. The mono-dimensional approach is motivated by the axial symmetricity of the rotor, and it facilitates sensitivity analyses related to the microgeometry uncertainty of the fluid film bearing. The use of 1D approaches in rotodynamic is still a highly debated argument, especially due to the recent improvements of computer performance and the consequently increased viability of high-fidelity models. Nevertheless, the time consumption is not the only (nor most important) advantage of 1D approaches: a low fidelity model is better comparable to, and is more easily calibrated with, experimental test data (3D high fidelity models are often not verifiable by observations). There are several ways to include the baseplate dynamics on the rotodynamic system and in this paper three methods of representation will be presented and compared: State Space Matrices (SSM), Frequency Response Function (FRF) and Dynamic Stiffness & Damping Method (DSM).
