Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
Control of Rotating Machines Bases Resonance by Means of Axial Forces
Submission Author:
Eduardo Padua , SP
Co-Authors:
Eduardo Padua, Reyolando Brasil
Presenter: Eduardo Padua
doi://10.26678/ABCM.COBEM2017.COB17-0119
Abstract
In this work, we study the effect of the alteration of the geometric stiffness, by means of axial forces application, in the natural frequency of bases of rotating machines. Two models are studied: a beam and a planar portal frame, all metallic, to keep them out of the resonance range. This region, near resonance, is considered an unsafe region, and comprises the range starting at 20% below this frequency and to 25% above it. Two tools were used to carry out the study: Rayleigh’s Method and the Finite Element Method (FEM). For the beam, a rectangular tube (60x60 profile) in structural steel is studied, using Rayleigh’s Method and the FEM. For the planar portal frame we used only the FEM. In this case, more profiles were analyzed. In the case of the beam, without any loading, we forced it to be inside the dangerous zone, by both Rayleigh and FEM. An axial force intervention was applied to change its frequencies. In the planar portal frame, the 60x60 profile was not inside the dangerous zone, while the others, 80x80 and I profile, were within the region {0.8Ω, 1.25Ω}. The study showed that the geometric stiffness has a very important influence on the natural frequencies of these machine bases.
Keywords
geometric stiffness, resonance, Fundamental natural frequency, natural frequencies, Finite Element Method (MEF), Rayleigh Method, Rotating machine
