NASTRAN DMAP TABEDIT 1

[ReshaCaner]

Hello,

I am new to the forum and pretty new to using DMAP, so my question may not be phrased very well, but I hope it comes across.

Suppose I have a model with 1000 GRIDS and I want to delete GRID 23 from BGPDT. Can I use TABEDIT to do that?

Thanks,
Caner

 

[dmapguru]

You could use TABEDIT to do it, but it would be a royal pain. You have to have a bunch of other tables available to drive the TABEDIT module to tell it exactly what you want to do. These days, it would be simpler to use the PARAML module with the TABDEL option to remove the words in BGPDT you want to delete.
On the other hand, why do you want to do this? You may cause yourself a lot of work downstream if you change BGPDT. If you describe what you want to achieve, there may be an easier route to achieve it that molesting BGPDT.
DG

 

[ReshaCaner]

I am doing a reduction on the original model and reading the reduced mass and stiffness matrices into another program. Currently this other program reads all the GRID point data from BGPDT and then throws away everything except those GRIDS used for the reduced model. That is a slow, inefficient way to do it.

It would be difficult to change the other program, so I was hoping to simply eliminate the unneeded GRIDs from BGPDT to reduce the time spent by the other program reading and discarding them.

 

[dmapguru]

Are you using the EXTSEOUT case control command to generate the reduced matrices, or some other method?

 

[ReshaCaner]

We're using a different method. PARAML seems to be working, so I think I'm set. I really appreciate the help.

 

[dmapguru]

If you don't go through the subDMAP EXTOUT route to get the boundary matrices, then you could use the BDRYINFO module to get the reduced GEOM1 table for the superelement boundary. Then use the GP1 module to get a reduced BGPDT from the reduced GEOM1. If you were using EXTSEOUT, then subDMAP EXTOUT is called and BDRYINFO gets executed in the process, so you would only need to weave in a GP1 call to get the reduced BGPDT.
DG

 

[dmapguru]

By the way, what happens if you have a local coordinate system defined on one of the boundary points? BGPDT is no good for that.