1. Introduction
Rotating machinery is commonly used in mechanical
systems, including machining tools, industrial turbomachinery,
and aircraft gas turbine engines. Vibration
caused by mass imbalance is a common problem in rotating
machinery. Imbalance occurs if the principal axis of
inertia of the rotor is not coincident with its geometric
axis. Higher speeds cause much greater centrifugal imbalance
forces, and the current trend of rotating equipment
toward higher power density clearly leads to higher operational
speeds. For example, speeds as high as 30,000 rpm
are not rare in current high-speed machining applications.
Therefore, vibration control is essential in improving
machining surface finish; achieving longer bearing, spindle,
and tool life in high-speed machining; and reducing
the number of unscheduled shutdowns. A great cost savings
for high-speed turbines, compressors, and other
turbomachinery used in petrochemical and power generation
industries can be realized using vibration control
technology.