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04-10-2017 10:06 AM

Hi Forum!

I'm facing an obstacle towards a good solution for my problem.

I want to create a datafile containing the grids and stiffness/mass matrices.

My current approach was to set "PARAM EXTOUT DMIGPCH", gather all grids from the stiffness matrix and find the corresponding entries in the underlying data => Voila, Grids + Matrices in one file.

Unfortunately, some solutions are too big to be handled comfortably by .pch files.

Now I would like to create one file containing the grids and one file containing the matrices, but in binary way => .op2

Until now, I have got 2 ideas for that:

__1.__ Create both .pch and .op2 file, but use the .pch only for the collection of information concerning the grids.

**Problem 1.** : I cant set EXTOUT two times ( EXTOUT DMIGPCH and EXTOUT DMIGOP2) Is there a way to create the matrices in two ways simultaneously?

__2.__ Only use the DMIGOP2.

**Problem 2.: **How can I gather information about the matrix entry grids from the op2 file? Is there a Nastran way to output also grid information?

Thank you very very much!

Regards

Benny

5 REPLIES

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04-10-2017 10:27 AM

Hi Benny

If you output your matrix using EXTSEOUT using the MATOP4 option, the grid data you require will be in the *.pch file on the EXTRN card, and your mass/stiffness matrix will be in high precision in the op4 file. If you put FORM=FORMATTED on the ASSIGN statement for the op4 file, your op4 matrix will be in ascii format.

Regards

Peter

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04-10-2017 12:33 PM

THank you Peter for your fast response.

If I'm using EXTSEOUT, I would have to define an ASET etc., am I right?

With my current input_deck, I only want to create the stiffness/mass matrices from a present model using all grids.

On account of this, I tried avoiding EXTSEOUT and using PARAM EXTOUT instead.

Or I am wrong?

Regards

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04-11-2017 04:44 AM

Hi Benny

You need to define on an ASET card each degree of freedom you want to appear in your mass/stiffness matrix.

Peter

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04-11-2017 08:25 AM

Hello Peter,

but in my approach, i only want to have Stiffness and Mass Matrices and the corresponding grids.

Therefore, I only used "PARAM EXTOUT DMIGPCH".

According to documentation, there is no solution performed but the bare matrix generation from the input.

This is what I am aiming for.

Unfortunately there's no PARAM EXTOUT MATOP4, am I right?

I dont want to select an ASET. If I am using PARAM, i do not select an ASET, I am only including the .bdf file and it generates my .pch containing the stiffness and mass matrices.

I want to achieve the same but as an OP2/OP4 file.

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04-11-2017 09:12 AM

PARAM, EXTOUT is the old interface to this capability. There is no MATOP4 option.

The EXTSEOUT case control is the new interface. It has been expanded to include the MATOP4 option.

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