"Zero thickness" error in SOL 600 (Patran)

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Discussion Overview

The discussion revolves around an error encountered during a SOL 600 analysis in Nastran, specifically a "zero thickness" error related to Quad4 elements. Participants explore potential causes and solutions, including model constraints and element behavior.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant reports a "zero thickness" error despite having defined element properties, questioning the source of the problem.
  • Another participant suggests that similar errors in other solvers may arise from violated constraints, particularly concerning external thickness limits affected by thermal expansion.
  • A participant mentions that after rebuilding the model, the error disappeared, indicating potential issues with the complexity of the model involving many parts and connectors.
  • One participant raises the possibility of hour-glassing issues associated with under-integrated elements as a potential cause of the error.

Areas of Agreement / Disagreement

Participants express varying viewpoints on the cause of the "zero thickness" error, with no consensus reached on a definitive solution or explanation for the issue.

Contextual Notes

The discussion highlights limitations related to the complexity of the model and the potential for constraints to be violated, but does not resolve these issues.

uribemax2
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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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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.
 
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.
 
What kind of elements are you using? Sounds a lot like an hour-glassing problem that some under-integrated elements suffer from.
 

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