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 values 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.

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 dampersAnnular seals