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Converting MSC Nastran Input Deck to NASTRAN-95
#1
Hi All,

Does anyone have experience converting an MSC or NX Nastran input deck to a format NASTRAN-95 can read?

Here are some of the things I've done and I think it has got me most of the way there:
-insert lines from "INCLUDE"-ed files
-added an "ID" card at the top
-changed SOL 101 to SOL 1
-replaced CBEAM and PBEAM cards with CBAR and PBAR cards (luckily my model doesn't use advanced CBEAM functionality)
-replaced CBUSH and PBUSH with a set of CELAS1 and PELAS elements
-made sure my coordsys ID numbers on the CQUAD4 and CTRIA3 elements are < 1,000,000 (NASTRAN-95 manual specifies this)
-converted all my line continuations to labeled line continuations with a unique label for each one
-changed the names of my RBE2 and RBE3 elements to CRBE2 and CRBE3

Now the CRBE3 elements seem to be giving me trouble. I am getting singular columns in the stiffness matrix, and forĀ  of my RBE3 reference gridpoints, it says "EXTERNAL GRID PT. .... NOT CONNECTED".

The only way these grid points are intended to be connected to the model is through the RBE3 elements. They are used to distribute a point-force (applied at the RBE3 reference grid point) to other nodes. Does NASTRAN-95 not allow this?

Thanks,
Josh
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#2
(12-18-2022, 01:11 AM)fontanj Wrote: Now the CRBE3 elements seem to be giving me trouble. I am getting singular columns in the stiffness matrix, and forĀ  of my RBE3 reference gridpoints, it says "EXTERNAL GRID PT. .... NOT CONNECTED".

The only way these grid points are intended to be connected to the model is through the RBE3 elements. They are used to distribute a point-force (applied at the RBE3 reference grid point) to other nodes. Does NASTRAN-95 not allow this?

Here are RBE3 definition in N95's UM.
           
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