Eventos Anais de eventos
COBEM 2017
24th ABCM International Congress of Mechanical Engineering
On the whirling direction of a probabilistic, undamped and asymmetric Laval rotor model subjected to residual unbalance
Submission Author:
Andreyson Jambersi , SP
Co-Authors:
Andreyson Jambersi, Samuel da Silva, Joao Pereira, Antonio Eduardo Turra
Presenter: Andreyson Jambersi
doi://10.26678/ABCM.COBEM2017.COB17-1010
Abstract
The main goal of this paper is to present a rotor modeled as an asymmetric and undamped Laval model subjected to residual unbalance which has uncertainties in the stiffness of its bearings, by using this model the backward whirling condition is identified. The motion equations of the rotor were described by complex coordinates to give information about the whirling direction according to the range of the spin speed in the rotor. The parametric stochastic model used considers the bearings stiffness as random variables and a Monte Carlo method is used to propagate their uncertainties. As results, it is possible to obtain the critical spin speed values, also called natural frequencies, and to identify the backward and forward whirling range of speeds, e.g. by assuming the uncertainties and considering it as a random variable. Some concerns about backward whirling are discussed and since it causes stress cycles of traction-compression in the shaft, it should be avoided. The probabilistic model obtained here has shown more robustness than a deterministic model in the backward whirling region.
Keywords
undamped stochastic Laval rotor model, complex coordinates, Uncertainties, Monte-Carlo simulation
