Small radial clearances between rotating and stationary components, as well as the health of surrounding equipment, demand that a machine achieve excellent lateral vibration performance.
BRG conducts several different types of analysis to determine a machine’s lateral vibration performance:
Provides a preliminary estimate of the critical speeds and their sensitivity to support dynamics. In addition, the influence of unbalance distribution as well as component damping can be assessed using the resulting mode shapes
Unbalance response analysis provides the best estimate of critical speed locations and vibration amplitudes. It is crucial for the assessment of separation margins, vibration limits and rubbing risks. Response due to nonsynchronous forcing phenomena can also be determined.
A vital analysis for avoiding self-excited instabilities, such as oil whirl and shaft whip. Damped eigenvalues are calculated to determine individual modes' log decrement which indicates their stability level. Influences of operation and components' condition are examined to assess the machine's stability robustness.
Dynamic interactions between different rotors or rotors with their stators can be significant in some machinery. Long coupling spacers, rigidly coupled trains and flexible casing structures demand these multilevel analyses
Events such as blade-loss, rubs, rotor drops, and deceleration through critical speeds require analysis in the time domain. Such events and their resulting motions can also be nonlinear. Transient analysis provides a useful design and diagnostic tool for these complex vibrations.
Undamped critical speed map for an offshore gas injection
compressor 
Undamped mode shapes of a six stage coker wet gas compressor
Measured vs. predicted unbalance response of a machine going
through its first critical speed 
API stability sensitivity analysis of an offshore gas injection
compressor 
Stability spectrum of a subsea compressor
supported by active magnetic bearings
Base stability measurements versus predictions for a machine
supported by tilting pad journal bearings 
Damped mode
shape of a propylene refrigeration compressor train with long coupling
spacer. 
Orbits from a seal rub simulation showing the generation
of half frequency whirl The influences of a shaft's surrounding components are often critical in defining a machine's overall lateral dynamics. BRG includes dynamics from the following:
Casing, substructure, & pedestal effects
Fluid film, active magnetic, and rolling element bearings
Electromechanical devices
Squeeze film dampers
Annular seals
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