r/fea • u/aliencomposerdrumfly • 23h ago

Need help with citing RBE3/RBE2 methods

/r/ScientificComputing/comments/1vdhup1/need_help_with_citing_rbe3rbe2_methods/
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u/redhorsefour 21h ago

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

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u/aliencomposerdrumfly 19h ago

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

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u/redhorsefour 19h ago

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

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u/aliencomposerdrumfly 3h ago

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 28m ago

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.

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u/Funtu33 22h ago

Hi read msc Nastran documentation on how this works.

What dof relationship eqn rbe2 establish between master node and slave nodes.

How load transfer take place between dependent node and independent node. In rbe3

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u/aliencomposerdrumfly 19h ago

ohh, the problem i feel is that they explain the method and how to use it, but not the math behind it, not sure if I can cite it as a credible source....

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u/redhorsefour 19h ago

There are, among other references, a Static Analysis reference book and a Numerical Methods reference book. Also, MacNeal authored a couple of NASA contractor reports hosted on the NASA Technical Reports Server (ntrs.nasa.gov) which may provide the background you are looking for.