Misalignment
Detection Using Operational Shape Deflection
Lin Liu,
Suri
Ganeriwala
SpectraQuest Inc., 8201 Hermitage Road, Richmond, VA 23228
Published: October 2005
Abstract
Misaligned rotating machinery is causing high
cost to industry due to prematurely damaged machinery, lost
production and excessive energy consumption. Therefore, a robust,
accurate and convenient misalignment detection technique is needed.
This work investigated the perspective of using operational
deflection shape (ODS) to check the machinery alignment condition.
It is expected the relative motion (amplitude and phase) among
different components of machine, especially the components connected
with the shaft, will be affected by misalignment. This work focuses
on the influence of misalignment on the motion of machine during one
rotation of the shaft. Two types of misalignment are studies, i.e.,
angular and parallel misalignments. The results suggest that ODS is
a potential method to detect misalignment.
Full Text (PDF)
Introduction
The test is performed on a
Machinery Fault SimulatorTM (MFS) made by SpectraQuest.
Three tri-axial accelerometers are mounted on the MFS. The coupling
is a rigid Ruland coupling. The nine channels acceleration data is
collected simultaneously using a VibraQuest hardware/software
system.
The acceleration data is exported to a ME’scope
model to visualize the ODS of the machine and to determine the
effect of misalignment on ODS.
Misalignment introduces synchronous force to the
machine structure. It a three dimensional force and produces several
harmonics of the running speed. In order to see the effect of
misalignment on ODS, it is important to separate non-synchronous
vibration from the synchronous components. The term synchronous is
used to describe vibration at and the harmonics of the running
speed. All other components are considered non-synchronous
vibration.
The raw data is processed in ME’scope data block
window to have the noise and other non-synchronized signal removed.
Ten shaft harmonics data is extracted and used in the ODS animation.
The ODS is animated in the time domain for the period of one shaft
rotation.
Fig. 1: Machinery Fault Simulator
RESOURCES 