Because the dynamic equations are expressed in different coordinate systems, the rotating and stationary reference frame approaches have different benefits and limitations.

If the mass of your rotating structure is on the rotational velocity axis (line model), those two approaches are equivalent as demonstrated in Example: Campbell Diagram Analysis of a Jeffcott Rotor.

With increasing rotational velocity and mass*radius product, the stationary reference frame results become less precise, but the simulation of a typical rotordynamics 3D solid shaft (where the product of mass outside the centreline and radius is small) can still be performed in this reference frame with good accuracy.

For large mass*radius product and/or large rotational velocity, the rotating reference frame approach must be used, even if the 3D structure is axisymmetric. In this type of analysis, the prestress effect due to the rotational velocity must be included. For an example of the procedure, see Example: Campbell Diagram Analysis of a 3D Bladed Shaft-Disk Assembly.

Use the following table to help you choose the best option for your application.

Reference Frame Considerations
Stationary Reference Frame	Rotating Reference Frame
In a static analysis, the gyroscopic force vector is given by: where represents the nodal velocity vector (specified via the IC or ICROTATE command).	In a static analysis, the Coriolis force vector is given by: where represents the nodal velocity vector (specified via the IC or ICROTATE command).
You can generate Campbell plots for computing rotor critical speeds. Frequency curve variations are usually smooth, and automatic sorting can be used.	You can generate Campbell plots for computing rotor critical speeds. Frequency curve variations are usually strong, and automatic sorting is not recommended.
Structure must be axisymmetric about the spin axis. It is not applicable to rotating structures with periodic (cyclic) symmetry such as impellers. With increasing rotational velocity and mass*radius product, the stationary reference frame results become less precise, but the simulation of a typical rotordynamics 3D solid shaft can still be performed in this reference frame with good accuracy.	Structure need not be axisymmetric about the spin axis. There is no accuracy loss in this reference frame, but the prestress effect due to the rotational velocity must be included.
The rotating structure can be part of a stationary structure in an analysis model (such as a gas turbine engine rotor-stator assembly). The stationary structure and supports (such as bearings) need not be axisymmetric.	The rotating structure must be the only part of an analysis model (such as a gas turbine engine rotor), except for stationary supports modeled with the COMBI214 element.
The rotating damping effect can be taken into account in rotating parts. See the CORIOLIS command for the RotDamp option and a list of elements supporting the rotating damping effect in a stationary reference frame.	The rotating damping effect can be taken into account in stationary COMBI214 elements only. If the element characteristics are isotropic, the element matrices are linear. Otherwise, corresponding periodic forces are generated in a nonlinear transient analysis. See the CORIOLIS command for the RotDamp option.
Supports more than one rotating structure spinning at different rotational speeds about different axes of rotation (such as a multi-spool gas turbine engine).	Supports only a single rotating structure (such as a single-spool gas turbine engine).
See the CORIOLIS command for the list of elements supported in the Stationary Reference Frame.	See the CORIOLIS command for the list of elements supported in the Rotating Reference Frame.