Unbalance Budgeting Optimizes Rotor Design for Assembly Performance -
Straight, Balanced Rotors Run Smoother! 2023-01-1006
In rotor engineering, one must achieve a rotor design incorporating a
well-controlled state of unbalance. A reduced nominal rotor unbalance assures
achieving permissible vibration responses during measurement.
Geometric feature controls associated with manufacturing drawings are root causes
of vibratory measurements during engine testing. Difficulties arise during
component design using software that fails to account for the presence of
unbalance, or the ability to achieve a balanced state for each rotor design.
Manufacturing procedures ensure that serial production articles are within
tolerance limits established by the manufacturing drawings. This process is
intended to ensure unbalance contributions estimated during the design phase
will permit vibration limits to be met during final acceptance test.
Performance of a rigid rotor under test cell conditions is dependent upon
effective control of runout and eccentricity between mating components.
Establishment of these tolerances must be accommodated in the design to ensure
which tolerance limits, and the resulting stacked tolerances are acceptable to
achieve established vibration limits during a final acceptance test. Otherwise,
this results in misalignment of the mass axis relative to its bearing
Using finite element methods, we can estimate the impact of several unbalance
distributions along the rotor axis and its excitation of rotor shaft-elastic
behavior. Predictive analyses with probabilities determine contributions toward
assembly vibration levels. We propose a method to account for the impact of
permissible manufacturing uncertainties during the earliest stages of rotor
design upon subsequent assembly processes.