Mfa. Azeez et Af. Vakakis, Numerical and experimental analysis of a continuous overhung rotor undergoing vibro-impacts, INT J N-L M, 34(3), 1999, pp. 415-435
This work aims in obtaining the transient response of an overhung rotor und
ergoing vibro-impacts due to a defective bearing. An overhung rotor clamped
on one end, with a flywheel on the other and impacts occurring in between,
due to a bearing with clearance, is considered. The variation of this syst
em, popularly known as the Jeffcot rotor, has been considered in previous w
orks, but there, the system has been reduced to a single degree of freedom
for ease of analysis. In this work the system is modeled as a continuous ro
tor including gyroscopic effects and the governing partial differential equ
ations are set up and numerically solved. The method of assumed models is u
sed to discretize the system in order to solve the partial differential equ
ations (PDE) bypartiaIly decoupling them and solving numerically. These par
tially decoupled equations are more accurate and less time consuming than t
he ones produced by finite elements or other numerical schemes. The most im
portant step in the success of this method is the selection of suitable mod
es for decoupling the system. It is not simply enough to select orthonormal
modes for decoupling the PDEs, but care must be taken to select the modes
as close to the actual system as possible. Using this method numerical expe
riments are run and representative results are presented. The different num
erical issues involved are also discussed. An experimental setup was also b
uilt to run experiments and validate the results. In the setup a defective
bearing is introduced at the flywheel end of the shaft to create radial imp
acts on the shaft. Laser sensor non-contact probes are used to measure the
displacement of the shaft a specified locations. Experimental observations
show satisfactory qualitative agreement when compared to the numerical inte
grations. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.