A SIMULIA e-Learning Resource
Created using Abaqus 6.8 and 6.12

Structures that exhibit cyclic symmetry provide the analyst with an opportunity to model an entire 360° structure at considerably reduced computational expense by analyzing only a single repetitive sector of the model.

There are two basic cases that can be analyzed:

Case 1: a model that has a cyclic symmetric initial state and a cyclic symmetric response

In this case the cyclic symmetry capability in Abaqus/Standard provides for linear and nonlinear analysis of cyclic symmetric structures with cyclic symmetric response. The condition that the structure be cyclic symmetric holds throughout the analysis, so in a loading step it is not possible to have any nonsymmetric deformation in the structure at any time. Therefore, only cyclic symmetric loads can be applied for this situation.

Case 2: a model with a cyclic symmetric initial state but a nonsymmetrical response

Extraction of a nonsymmetrical response for a cyclic symmetric structure is currently available only for eigenfrequency extraction analysis using the block Lanczos method and for frequency domain, modal-based steady-state dynamic analysis.  For these analysis types, the full response of an entire cyclic symmetric structure is represented as a linear combination of several independent basic responses, each of which corresponds to some k-fold cyclic symmetry:

Narrated Video

This video was created using Abaqus 6.8, however the concepts demonstrated still apply in Abaqus/CAE today.

The following video includes:
   - An introduction (0-0:43)
   - An Abaqus/CAE demonstration (0:43-5:03)
         -- 0:43-3:44  Defining a cyclic symmetry interaction
         -- 3:44-5:03  Visualization of results

This video was produced using Abaqus 6.8 and can also be found in the Introduction to Abaqus 6.8 web-based training site.

Now You Try It!

Download the attached file CyclicSymmetry-fan-Model-Abaqus612.zip and follow the included step-by-step instructions (CyclicSymmetry-fan-StepByStep-Abaqus612.pdf) to create and visualize a cyclic symmetric analysis of a fan with a nonsymmetrical response.

This exercise was produced using Abaqus 6.12.

References

---- “Analysis of models that exhibit cyclic symmetry,” Section 10.4.3 of the Abaqus 6.12 Analysis User's Manual
---- “Defining cyclic symmetry,” Section 15.13.19 of the Abaqus/CAE 6.12 User's Manual   
---- “Analysis of a rotating fan using substructures and cyclic symmetry," Section 2.2.1 of the Abaqus 6.12 Example Problems Manual  

-- More SIMULIA e-Learning Resources  --