"Zero thickness" error in SOL 600 (Patran)

In summary, the conversation discusses a problem with a SOL 600 analysis in Nastran, where some elements are giving an error of "zero thickness" despite being properly defined. The model has been checked and it is suspected that the issue may be with constraints being violated. After rebuilding the model, the problem is resolved, but it is still unknown why it occurred in the first place. The conversation also mentions the possibility of it being an hour-glassing problem with under-integrated elements.
  • #1
uribemax2
2
0
Hello all,

I am doing a SOL 600 analysis but Nastran gives me an error of "zero thickness" in some elements. Obviously, I checked those elements and they have properly defined their properties so I don't know what can I do.

I've done a lot of linear and nonlinear static analysis in that model and all of them have run okey, therefore I suppose that the model is well constituted, where could be the problem?

The model is all formed by Quad4 elements and Patran version is 2010.

Thanks in advance.
 
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  • #2
I'm not familiar with Nastran, but other problem solvers give this type of error when the constraints are violated.

For example, the external thickness is limited to 0.010, and the layers add up to 0.010, but the external limit is violated when heat is applied, due to thermal expansion.
 
  • #3
Many thanks for answering.

I tried to define constraints again but anything changed so I've rebuilt my model and surprisingly the problem has disappeared. I am working in a big model with a lot of parts and connectors so that could be the issue. It's a pity that I still don't know why it didn't work properly but now I can continue working so that's all.

Thanks for helping.
 
  • #4
What kind of elements are you using? Sounds a lot like an hour-glassing problem that some under-integrated elements suffer from.
 

1. What does "zero thickness" error in SOL 600 mean?

The "zero thickness" error in SOL 600 refers to an issue that occurs in the finite element analysis (FEA) software Patran. It occurs when a finite element mesh contains elements with zero thickness or when a shell element becomes infinitely thin. This error can lead to incorrect results and should be addressed before running any simulations.

2. What causes the "zero thickness" error in SOL 600?

The "zero thickness" error can be caused by a few different factors. It could be due to an error in the geometry or meshing process, such as overlapping elements or incorrect element orientation. It can also occur when using thin or curved shell elements, as these can become infinitely thin in certain areas. Additionally, the error can be caused by element deletion or distortion during the simulation process.

3. How can the "zero thickness" error be avoided in SOL 600?

To avoid the "zero thickness" error in SOL 600, it is important to carefully check the geometry and mesh before running the simulation. Make sure there are no overlapping elements or incorrect element orientation. If using shell elements, try to use thicker elements or adjust the geometry to avoid thin or curved regions. During the simulation, it is also important to monitor for any element deletion or distortion and make adjustments if necessary.

4. How is the "zero thickness" error detected in SOL 600?

The "zero thickness" error can be detected in SOL 600 by running a mesh check or using the diagnostic tools in Patran. These tools can identify any elements with zero thickness and provide a list of the affected elements. Additionally, if the simulation results seem incorrect or unstable, it could be a sign of the "zero thickness" error.

5. How can the "zero thickness" error be fixed in SOL 600?

The "zero thickness" error can be fixed in SOL 600 by adjusting the geometry or mesh to avoid thin or overlapping elements. If necessary, thicker or different types of elements can be used. If the error occurs during the simulation, it may be necessary to refine the mesh in the affected area or use stabilization techniques. In some cases, it may be necessary to consult with a FEA expert for further assistance.

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