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Quality of deformed elements
Posted 6 mag 2016, 06:39 GMT-4 Mesh, Structural Mechanics 4 Replies
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Dear all,
I have a question about models that use solid mechanics and experience large deformations. Imagine a 2D square heavily compressed, for example. To my understanding, at the end of the simulation it is possible to view the deformed elements of the mesh by checking the "Wireframe" option in one of the contour plots (it is correct, by the way?)
Now, how do I check quantitatively the quality of the deformed mesh? Is there a variable that I could plot? And, if the quality of the elements drops too low, is there a way to enable remeshing of the geometry during the simulation?
Thank you for your help,
Best,
Pietro
I have a question about models that use solid mechanics and experience large deformations. Imagine a 2D square heavily compressed, for example. To my understanding, at the end of the simulation it is possible to view the deformed elements of the mesh by checking the "Wireframe" option in one of the contour plots (it is correct, by the way?)
Now, how do I check quantitatively the quality of the deformed mesh? Is there a variable that I could plot? And, if the quality of the elements drops too low, is there a way to enable remeshing of the geometry during the simulation?
Thank you for your help,
Best,
Pietro
4 Replies Last Post 9 mag 2016, 11:57 GMT-4
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Posted:
8 years ago
Hi Pietro,
It sounds like you're looking for "Automatic Remeshing" which you will find documented in the COMSOL Multiphysics Reference Manual, version 5.2, page 1029.
Best regards,
Jeff
It sounds like you're looking for "Automatic Remeshing" which you will find documented in the COMSOL Multiphysics Reference Manual, version 5.2, page 1029.
Best regards,
Jeff
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Posted:
8 years ago
Dear Jeff,
thank you for your reply. I have already looked at the Comsol documentation, but the condition for enabling the automatic remeshing for poor element quality is available only when the feature "Moving mesh" is added to the model. I think this is due to the requirement of the variable ale.minqual in the remeshing options. To my knowledge, this variable becomes available only when the latter module (Moving Mesh) is added to the model. Since the use of Moving Mesh coupled to Solid Mechanics is discouraged in the documentation, and since the options in this interface have to be carefully selected, I was wondering if there could be another way for remeshing my geometry.
Thanks again, any further help from you is more than welcome!
Best,
Pietro
thank you for your reply. I have already looked at the Comsol documentation, but the condition for enabling the automatic remeshing for poor element quality is available only when the feature "Moving mesh" is added to the model. I think this is due to the requirement of the variable ale.minqual in the remeshing options. To my knowledge, this variable becomes available only when the latter module (Moving Mesh) is added to the model. Since the use of Moving Mesh coupled to Solid Mechanics is discouraged in the documentation, and since the options in this interface have to be carefully selected, I was wondering if there could be another way for remeshing my geometry.
Thanks again, any further help from you is more than welcome!
Best,
Pietro
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Posted:
8 years ago
Hi,
You can use the variable solid.J to get an idea of the local volume change (and its gradients). Note that since the formulation in the Solid Mechanics interface is on material frame, the numerical integration is done over the original mesh. The deformation gradients do however enter through the strain expressions, so a highly deformed element will still be unsuitable. The deformation gradients and stretches can also be used as results to evaluate distortions.
You are right in that Solid Mechanics should not be used on a moving mesh. The best option is usually to create an initial mesh which is adapted to the anticipated deformations. if elements are expected to be extended in one direction, you can start by having them elongated in the other direction. It is better to have an aspect ratio changing from 1:3 to 3:1 than from 1:1 to 9:1.
Regards,
Henrik
You can use the variable solid.J to get an idea of the local volume change (and its gradients). Note that since the formulation in the Solid Mechanics interface is on material frame, the numerical integration is done over the original mesh. The deformation gradients do however enter through the strain expressions, so a highly deformed element will still be unsuitable. The deformation gradients and stretches can also be used as results to evaluate distortions.
You are right in that Solid Mechanics should not be used on a moving mesh. The best option is usually to create an initial mesh which is adapted to the anticipated deformations. if elements are expected to be extended in one direction, you can start by having them elongated in the other direction. It is better to have an aspect ratio changing from 1:3 to 3:1 than from 1:1 to 9:1.
Regards,
Henrik
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Posted:
8 years ago
Dear Henrik,
thank you very much for your answer, I will consider what you suggested for my future simulations.
Best,
Pietro
thank you very much for your answer, I will consider what you suggested for my future simulations.
Best,
Pietro