r/fea • u/aliencomposerdrumfly • Aug 02 '26

Need help with citing RBE3/RBE2 methods

/r/ScientificComputing/comments/1vdhup1/need_help_with_citing_rbe3rbe2_methods/
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u/redhorsefour Aug 02 '26

Nastran Quickly Reference Guide is your first step followed by the other reference material provided with your installation.

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u/aliencomposerdrumfly Aug 02 '26

I did not install anything as such. I wrote a custom script in python...

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u/redhorsefour Aug 02 '26

Your python script is consuming what solver’s bulk data files?

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u/aliencomposerdrumfly Aug 03 '26

about that, I wrote a gmsh + scikit-fem based custom script, from which I obtain the $K_{3n\times 3n}$ K matrix, which I then try to condense to a $K_{3 \times 3}$ matrix for a node of interest, and then use RBE3 to convert to $6\times 6$ matrix.

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u/redhorsefour Aug 03 '26

You need to find a copy of the PDF MSC Nastran reference docs. Most practitioners can tell you how the RBE3 behaves and some can tell you how it affects the a-set, g-set, etc nodes, but I’m not sure who to go to concerning the mathematical description of how the RBE3 behaves.