Modeling misaligned rotors

To model misaligned rotors, you create a CLINK connection and apply the Geometric Misalignment load to it.

• CLINK is a 1D connection element that defines a connection between coincident nodes in the same rotor or different rotors that rotate at the same speed and in the same direction. The CLINK connection element automatically outputs the forces at the location of the misalignment.

• The Geometric Misalignment load applies the forces that are necessary to model different types of misalignment so that you can study the dynamics of the misalignment on the rotating part or assembly.

Types of misalignment

To misalign a rotor, you use the Geometric Misalignment load to apply translation and rotation options to the selected CLINK connection. The translation and rotation options define the type of misalignment.

The Geometric Misalignment load lets you model the following types of misalignment:

Type of misalignment	Example
No misalignment or offset (The rotor halves are shown separated for clarity. In rotors with no misalignment or offset, the two nodes are superimposed.)
(1) Axial offset
(2) Translational (parallel)
(3) Translational (parallel) and (4) rotational (angular)

All of the misalignments are defined in terms of cylindrical coordinates. You can apply these types of misalignments in any combination. For a summary of the misalignment combinations and the corresponding options you need to set, see Misalignment combinations in Geometric Misalignment dialog box (Simcenter Nastran).

Post-processing misalignments

The forces are output automatically in the CLINK element. In the Post Processing Navigator, the CLINK forces are under the solution node→Structural→Graphs node in the graphs named as follows:

• Force_Vector-Complex[(LINK_id)ElementidComponentid]

By default, the Y-axis is set to a linear scale. To change that to a logarithmic scale, right-click the Y-axis and choose Types→Log.

Where do I find it?

Adding the CLINK element

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter Nastran as the specified solverRotor Dynamics as the specified analysis typeSOL 414,111 Harmonic Response or SOL 414,129 Transient Response as the specified solution type
Command Finder	1D Connection
Location in dialog box	Connection Element group→Type list→CLINK

Adding the Geometric Misalignment load

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSimcenter Nastran as the specified solverRotor Dynamics as the specified analysis typeSOL 414,111 Harmonic Response or SOL 414,129 Transient Response as the specified solution type
Command Finder	Geometric Misalignment
Simulation Navigator	Right-click a Load Container→New→Geometric Misalignment

Modeling misaligned rotors, Simcenter 3D 2021.1 Series

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