Altair RISE

A program to recognize and reward our most engaged community members

Nominate Yourself Now!

CMS reduction and export to op4 file

Hello,

I am trying to perform a CMS reduction, and include load vectors. I then want to export mass, stiffness, load vectors and recovery matrix to an op4 file.

To add load cases to the CMSMETH I am using the LOADSET flag. To export the data to an .op4 file I use PARAM,ROMAX,YES,YES

By doing this I can export the mass, stiffness and recovery matrix to the op4 file, but the load vectors are not present. I use the following:

CMSMETH = 9
MODEL=ALL,ALL,ALL
SPC = 1
TEMPERATURE(INITIAL) = 4
SUBCASE 1
BEGIN BULK
CMSMETH 9 CBN 2000.0 0 LAN
LOADSET BOTH 1 2 3

PARAM,EXTOUT,DMIGPCH
GRAV,1,,9.81,1.0,0.0,0.0,$
GRAV,2,,9.81,0.0,1.0,0.0,$
GRAV,3,,9.81,0.0,0.0,1.0,$

...

PSOLID 1 1 0
MAT1 1 71000. 0.315 2.66E-9 2.31E-5 0.

Alternatively I also tried to use PARAM,EXTOUT,DMIGOP4 instead of PARAM,ROMAX,YES,YES. In this case however, only mass and stiffness are exported. How can I export everything (mass, stiffness, load vectors and recovery matrix) to the .op4 file?

Thanks,

David

Find more posts tagged with

English

OptiStruct

v2022.0

Accepted answers

All comments

harte

David,

If you look in the .out file do you see any warning messages like the following?

*** WARNING # 1495
Misplaced control card: 'LOADSET' in bulk section (skipped).

Ideally

CMSMETH 9 CBN 2000.0 0 LAN
LOADSET BOTH 1 2 3

would be written as:

CMSMETH,9,CBN,2000.0,,0,LAN
,LOADSET,BOTH,1,2,3

(LOADSET is not the first field in continuation line, but 2nd field).

Not sure if this is the solution to your problem, but something to check out.

Regards,

Greg.

Alberto Campagna

Hello David,

reduced loads are not exported in op4 format. I see 2 solutions since you are using GRAV loads:

1) apply them in the residual run and the loads will be applied to the mass of the SE also;

2) use another format for reduction as pch.

Regards.

Alberto

David Cha_22200

Hi Greg and Alberto,

Thanks a lot for the replies. I think the LOADSET card worked ok, as I can see the loadvectors being exported in the pch file (and not on the op4) as Alberto was mentioning. I am attaching the input and output files as reference (I have not uploaded the op4 as too big).

I have a few more questions if you don't mind.

- Are the recovery matrix columns associated with the load vectors also NOT exported to the op4. Is there any way to export them?

- Is it possible to include more that 3 loadset in the cms reduction LOADSET card?

- Referring to this question I asked previously CMS reduction and thermal load - OptiStruct - Altair Products - Altair Community Has there been any development in Optistruct to include thermal loads during reduction?

Thanks again for the help,

David

SimpleHousingOptistruct.dat

SimpleHousingOptistruct.out

SimpleHousingOptistruct.pch

SimpleHousingOptistruct.stat

Alberto Campagna

"Are the recovery matrix columns associated with the load vectors also NOT exported to the op4. Is there any way to export them?" - No, but it should be easy to retrieve them. Column 1 is the reduced load with the lower id and so on with increasing ids.

" Is it possible to include more that 3 loadset in the cms reduction LOADSET card?" - I am not aware of any limitation on the number of loads that can be reduced.

"Referring to this question I asked previously CMS reduction and thermal load - OptiStruct - Altair Products - Altair Community Has there been any development in Optistruct to include thermal loads during reduction? " - It is still unsupported.

Alberto

David Cha_22200

Thanks a lot for the replies.

Sorry for having further questions, but when you say "No, but it should be easy to retrieve them. Column 1 is the reduced load with the lower id and so on with increasing ids.", what file are we talking about?

I have checked the op4 and the pch file and I see no trace of the recovery matrix columns from the thermal loads (the thermal loads themselves are in the pch file ).

Eg in my example I have 4 6dofs condensation nodes + 6 internal modes, and the op4 files contain 30 columns (6*4+6). However the 3 columns from the gravity loads are not there. I would have expected 33 columns.

Thanks again,

David

Alberto Campagna

Thanks a lot for the replies.

Sorry for having further questions, but when you say "No, but it should be easy to retrieve them. Column 1 is the reduced load with the lower id and so on with increasing ids.", what file are we talking about?

I have checked the op4 and the pch file and I see no trace of the recovery matrix columns from the thermal loads (the thermal loads themselves are in the pch file ).

Eg in my example I have 4 6dofs condensation nodes + 6 internal modes, and the op4 files contain 30 columns (6*4+6). However the 3 columns from the gravity loads are not there. I would have expected 33 columns.

Thanks again,

David

I am talking about .pch file since op4 does not have reduced loads nor recovery matrix.

Alberto