Multi-stage cyclic symmetry in Simcenter Samcef

In the Simcenter Samcef environment, you can perform an analysis of multi-stage cyclically periodical structures (also called cyclic symmetry).

Cyclic symmetry (mono-stage)

A cyclically periodical structure is composed of a set of N identical substructures (called reference sectors or segments), placed symmetrically around an axis.

Each sector is in contact with only two other identical sectors.

If a sector is defined at the revolution α angle, the same identical sector appears at α + nβ, where β is equal to 2PI/N.

N depends on the studied structure and n is an integer smaller than N. The sector therefore covers the [α, α + β] angles range.

Once the structure geometry is defined from α to α + β, the remainder of the structure can be obtained by repeating rotations of magnitude β.

The advantage of the method is that you can solve a reference sector instead of a complete 3D model.

You define the N number of segments in the Cyclic symmetry mesh collector options (Simcenter Samcef) of the mesh collectors that represents the reference sector.

You then define cyclic symmetry conditions on that reference sector in specialized simulation objects.

You can solve cyclic symmetry models in Linear Static, Modal, or Nonlinear analyses.

Multi-stage cyclic symmetry

Many rotating engines (like compressors) have several stages, and each stage has its own cyclic symmetry characteristics.

For the mesh collectors that represent the reference sector of a given stage, you define:

• N number of segments

• Stage number

You repeat this for each different stage of your model.

You define these properties in the Cyclic symmetry mesh collector options (Simcenter Samcef) of the mesh collectors that represent the reference sector.

You then define cyclic symmetry conditions on each of these reference sectors in specialized simulation objects. You also need to define inter-stage connection to connect the different stages of your model.

You can solve multi-stage cyclic symmetry models in Linear Static, Modal, or Nonlinear analyses.

Defining a cyclic symmetry model

Step	Summary	Remark
1.	Create the FEM and define the cyclic symmetry reference axis	For more information, see Setting up the cyclic symmetry reference axis (Simcenter Samcef).
2.	Mesh your model, and define materials and physical properties.	Note: When you mesh a reference sector, the mesh of the source face and the mesh of the target face of the reference sector can be dissimilar.
3.	For all the mesh collectors in your model, activate the cyclic symmetry option, and define the number of segments (N) and the stage number.	For more information, see Cyclic symmetry mesh collector options (Simcenter Samcef).
4.	Define loads and constraints.
5.	Add specific cyclic symmetry, translational periodicity or inter-stage definition simulation objects (if multi-stage cyclic symmetry).	In these simulation objects, the software defines cyclic conditions on the reference sector that match the reference sector geometry.If needed, the software corrects the number of segments you defined in the mesh collector.For more information, see Cyclic symmetry simulation objects (Simcenter Samcef).
6.	Define the solution options.	For more information, see Cyclic symmetry solutions (Simcenter Samcef).
7.	Solve the model.	For more information, see Solve the model.You can also see Solution Monitor.
8.	(Optional) Post-process the results.	For more information, see Post-processing.
9.	(Optional) Perform a recombination.	For more information, see Cyclic symmetry solutions (Simcenter Samcef).

For more information on the cyclic symmetry theory, see the Samcef cyclic symmetry page in the Simcenter Samcef documentation.

Look up more details

Cyclic Symmetry dialog box (Simcenter Samcef)

Translational Periodicity dialog box (Simcenter Samcef)

Interstage Definition dialog box (Simcenter Samcef)

Solution dialog box (Simcenter Samcef Cyclic Symmetry Recombination Analysis)

Physical and element properties support (Simcenter Samcef)

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Multi-stage cyclic symmetry in Simcenter Samcef, Simcenter 3D 2021.1 Series

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