Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
The influence of the bearing angular stiffness in rotordynamics
Submission Author:
Thiago da Silva , PR , Brazil
Co-Authors:
Lucas Bortolotto, Francisco José Doubrawa Filho, Carlos Alberto Bavastri, Thiago da Silva
Presenter: Thiago da Silva
doi://10.26678/ABCM.COBEM2017.COB17-1326
Abstract
The rotordynamic analysis plays an important role in a high-speed machine mechanical design. Unwanted shaft lateral vibrations due to resonance can be easily avoided in general mechanical systems, but even in slow speed hydro-generators, the rotating system must be able to withstand an over speed of about three times the rated speed. For this reason, an accuracy rotordynamics model to predict its dynamic behavior is very important for reliable and uninterrupted operation of these machines. In some cases, the bearings can combines radial and axial constrains. This kind of assembly adds stiffness in the slope degree-of-freedom on the bearing. The majority of bearing models for rotordynamic calculation presents stiffness in the displacement degrees-of-freedom only, a two by two order matrix, disregarding the slope stiffness. To handle the angular stiffness, the bearing model must be expanded to at least a fourth order matrix, to accommodate also the angular stiffness coefficients. In this work it will be presented a methodology to identify the angular stiffness coefficient. The methodology is based in an inverse problem, using the unbalance response obtained experimentally and its numerical equivalent in an optimization environment. The resultant parameters and its equivalent obtained through analytical model founded in literature will be compared. For identification propose, an experimental set up will be implemented.
Keywords
rotordynamic analysis, bearing model, angular stiffness, Optimization
