Vibration analysis of a structure with cyclic symmetry

In summary, the conversation discusses the use of complex numbers in vibration analysis of a structure with cyclic symmetry. The question being asked is whether the FE analysis only considers one segment (such as one blade in a turbine wheel) or if it takes into account all segments/sectors/blades in the output. The speaker apologizes for the basic nature of the question and asks for assistance.
  • #1
svishal03
129
1
Lets us say we are doing a vibration analysis of a structure with cyclic symmetry

In very brief (as pointed out by AlephZero in one of his excellent reply) the whole motion can be represented by complex numbers which describe the motion of one segment.

Now, my question is:

1)Is it that,whilst doing the FE analysis we have just one segment (example 1 blade only- considering a turbine wheel) going into the solver - i.e. nodes/eleemnts of just 1 blade?

2)But the output comprises of all segments- i.e. all the sectors / blades?

Please help me with this fundamental question!

Sorry for being too basic
 
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  • #2
Please can anyone help?Will be grateful
 
  • #3
Please canyone help?
 

Related to Vibration analysis of a structure with cyclic symmetry

1. What is cyclic symmetry in vibration analysis?

Cyclic symmetry in vibration analysis refers to a repeating pattern or geometry in a structure that results in identical vibration modes at equidistant points around the structure. This can simplify the analysis process and reduce computation time.

2. What are the benefits of using cyclic symmetry in vibration analysis?

The main benefit of using cyclic symmetry in vibration analysis is the reduction in computational effort and time. This is because only a portion of the structure needs to be analyzed, and the results can be extrapolated to the rest of the structure. Additionally, cyclic symmetry can help identify potential failure modes and improve the accuracy of the analysis.

3. How is cyclic symmetry taken into account in vibration analysis?

In vibration analysis, cyclic symmetry is taken into account by using specialized techniques such as the Craig-Bampton method or the component mode synthesis method. These methods allow for the reduction of the original structure to a smaller model that represents the cyclic symmetry, making the analysis more efficient.

4. Can cyclic symmetry affect the accuracy of vibration analysis?

Yes, cyclic symmetry can affect the accuracy of vibration analysis if not properly accounted for. If the symmetry is not accurately represented in the analysis model, it can result in incorrect predictions of vibration modes and frequencies. It is important to carefully consider the symmetry of the structure and use appropriate techniques to account for it.

5. Are there any limitations to using cyclic symmetry in vibration analysis?

While cyclic symmetry can greatly simplify vibration analysis, there are some limitations to its use. Structures with complex geometries or non-uniform properties may not exhibit cyclic symmetry, making it difficult to apply this technique. Additionally, the presence of damping or nonlinear behavior can also affect the accuracy of the analysis.

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