A1 Journal article (refereed), original research

Unbalance Estimation for a Large Flexible Rotor Using Force and Displacement Minimization

Open Access publication

Publication Details
Authors: Choudhury Tuhin, Viitala Risto, Kurvinen Emil, Viitala Raine, Sopanen Jussi
Publisher: MDPI
Publication year: 2020
Language: English
Related Journal or Series Information: Machines
Volume number: 8
Issue number: 3
ISSN: 2075-1702
eISSN: 2075-1702
JUFO-Level of this publication: 1
Open Access: Open Access publication


Mass unbalance is one of the most prominent faults that occurs in
rotating machines. The identification of unbalance in the case of large
flexible rotors is crucial because in industrial applications such as
paper machines and roll grinders, high vibrations can adversely affect
the quality of the end product. The objective of this research is to
determine the unbalance location, magnitude and phase for a large
flexible rotor with few measured coordinates. To this end, an
established force-based method comprising of modal expansion and
equivalent load minimization is applied. Due to the anisotropic behavior
of the test rotor, the force method required at least six measured
coordinates to predict the unbalance with an error of 4 to 36%. To
overcome this limitation, an alternate method, eliminating the use of
modal expansion, is proposed. Here, displacements generated by varying
the location of a reference unbalance along the rotor axis, are compared
to measured displacements to detect the unbalance location.
Furthermore, instead of force-based fault models, the minimization of
displacements at measured locations determines the unbalance parameters.
The test case in this study is the guiding roll of a paper machine and
its different unbalance states. The algorithm is tested initially with a
simulation-based model and then validated with an experimental set up.
The results show that the displacement method can locate the unbalance
close to the actual location and it can predict the unbalance magnitude
and phase with only two measured coordinates. Lastly, using measured
data from 15 measurement points across the tube section of the test
rotor, a comparison shows how the selection of the two measured
locations affects the estimation accuracy.

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Last updated on 2020-10-08 at 10:48