Modeling cyclic symmetry (SOL 414)

You can create and solve cyclic symmetric models in all SOL 414 types except SOL 414,111 harmonic response analysis. The cyclic symmetry method reduces the time needed to create and solve a full 360 degree model.

To create a cyclic symmetric model, mesh a fundamental segment of the model geometry with 3D solid elements. A fundamental segment is a subset of the entire model geometry that, when placed at angular increments of 2π/N, where N is the number of fundamental segments, allows you to recover the entire model geometry.

For SOL 414,110 complex modal analysis, the displacement DOF associated with the 3D solid elements are represented as a series, where each term in the series represents additional harmonic behavior. For example, see Modeling axisymmetry.

You request the harmonic index values for which you want complex modes to be computed with a Harmonics Set modeling object. The complex modal solution occurs for each harmonic index independently.

For example, if you request 10 modes on the Complex Eigenvalue modeling object for the solution, and you request solutions for the zeroth, first, second harmonics, a discrete complex modal solution occurs for each of these harmonics.

• For cyclic symmetric models where an even number of fundamental segments (N is even) is needed to recover the entire geometry, the allowable set of harmonics is 0, 1, ...., N/2.

• For cyclic symmetric models where an odd number of fundamental segments (N is odd) is needed to recover the entire geometry, the allowable set of harmonics is 0, 1, ...., (N-1)/2.

For SOL 414,101 maneuver load analysis and SOL 414,129 transient response analysis, only the zeroth harmonic is used to represent the displacement DOF.

Coupling cyclic symmetric rotor to rotor axis

For information on coupling 3D cyclic symmetry with a 2D axisymmetric portion of the model, see Coupling 2D and 3D portions of a model (SOL 414).

Post-processing cyclic symmetry results

To visualize all sectors of the 3D cyclic symmetry component, use the Results Recombination command. You can use this same command to visualize coupled 2D axisymmetric and 3D cyclic symmetry models that are connected with the Fourier Multi Harmonic and 3D Coupling simulation object. For more information, see Post-processing 3D cyclic symmetry and 2D axisymmetric results for a rotor dynamic analysis (SOL 414).

Where do I find it?

Application	Pre/Post
Prerequisites	A Simulation file as the work and displayed partSimcenter Nastran as the specified solverRotor Dynamics as the specified analysis typeOne of the following as the specified solution type:SOL 414,101 ManeuversSOL 414,103 Eigenvalue and Superelement ReductionSOL 414,110 Complex Modal Analysis****SOL 414,129 Transient Response
Command Finder	Modeling Objects
Location in Dialog Box	Type list→Harmonics Set→Create

How do I

Create connection elements between coincident nodes with CBEAR2 elements

Define rotor bearing or bushing properties

Create a rotor region

Define a rotor

Define the rotor dynamics solution parameters

Create an unbalance mass

Define forcing frequencies

Define nonlinear transient parameters

Set the duration of the simulation

Create a modeling object

Assign a modeling object to a solution or solution subcase

Learn more

Rotor dynamic analysis (SOL 414)

Modeling axisymmetry (SOL 414)

Creating connection elements on a rotor model (SOL 414)

Damping (SOL 414)

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Modeling cyclic symmetry (SOL 414), Simcenter 3D 2021.1 Series

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