Can I use symmetry in modal analysis in FEA

In summary, the conversation discusses the use of symmetry in FE analysis for symmetric shapes in boundary conditions and geometry. The speaker mentions that symmetry can be utilized depending on the model, and provides a resource for more information. They also suggest sharing a CAD model or image for further evaluation. Additionally, the conversation mentions the use of symmetry in injection molding using FEA software for simulating plastic flow in molds. Symmetry is used to save time and with regards to the number of cavities.
  • #1
Mohamed_Wael
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I am doing FE analysis for symmetric shape in boundary conditions and geometry, I would like to know if I can use symmetry in my analysis or not. I have tried to run trials, the results are very similar but I am not sure if this just a coincident
 
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  • #2
Hi Mohamed_Wael,
depending on your model, you can make use of symmetry. You can read more about the preprocessing here.
If you for example take this project of a spring mount as an example, you'll find out that here they made use of symmetry.
This, however doesn't mean you can do it anytime.
Maybe describe your CAD model or post a picture of it to help us understand what you're trying to do and we can help you evaluate.
 
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  • #3
In injection molding, we use a type of FEA software called MoldFlow that simulates plastic flowing in a mold. If the part is symmetrical, then we can use symmetry to save time. We also use symmetry with regards to the full shot vs. the number of cavities. So if I have four cavities on one runner, we model one cavity and a quarter of the runner.
 

1. Can symmetry be used in modal analysis in FEA?

Yes, symmetry can often be used in modal analysis in FEA to reduce the computational effort and time required for the analysis.

2. How does symmetry affect the results of modal analysis in FEA?

Symmetry can affect the results of modal analysis in FEA by reducing the number of degrees of freedom in the model, which can lead to faster and more efficient computations. However, it can also introduce some errors in the results if the symmetry assumption does not accurately represent the actual geometry and loading conditions.

3. What types of symmetry can be used in modal analysis in FEA?

There are typically three types of symmetry that can be used in modal analysis in FEA: plane symmetry, rotational symmetry, and reflective symmetry. The type of symmetry used will depend on the geometry and loading conditions of the model.

4. Are there any limitations to using symmetry in modal analysis in FEA?

Yes, there are some limitations to using symmetry in modal analysis in FEA. The symmetry assumption may not accurately represent the actual geometry and loading conditions, which can lead to errors in the results. Additionally, not all models or structures are symmetric, so symmetry cannot always be applied.

5. How do I determine if symmetry can be used in my modal analysis in FEA?

You can determine if symmetry can be used in your modal analysis in FEA by carefully examining the geometry and loading conditions of your model. If your model exhibits any type of symmetry, you can consider using it in your analysis. However, it is important to also verify that the symmetry assumption accurately represents the actual conditions in order to ensure accurate results.

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