How to make the result from the Superelement reduction more accurate?

noravivian.yazdandoostkhosravi over 3 years ago

I created a plate with an frequency dependent force from 20 to 1000 Hz. I analysed the plate with SOL 111. For the Frequency Range of Interest for the Real Eigenvalue Extraction and for the Frequency Response solution parameters frequency recovery points I took 20 - 1000 Hz as attitude.

I create a graph out of the reults. The blue graph is the one with the full model. The red one is the result out of a superelement analysis.

How do I get a result with superelement method which is more accurate to the original?

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0 stefano.fabbri 11 months ago
Dear all,

I'm really interested in the approach you followed, but not sure if applicable to my case.

I need to perform a sine analysis where some external superelements have higher damping wrt to residual structure.

I also need to deliver a reduced model (again, by external SE) form the previous one.

It is very likely that before final delivery, we need to perfom sensitivity analyses changing the damping value

Therefore I want to apply it "externally" to SEs in the residual run.

In theory I should :

create a SUBCASE for every SE using SUPER instruction assigning damping value: as damping is additive, proper values shoud be chosen wrt residual damping to avoid overdamping for SE;

create residual SUBCASE with nominal inputs.

What I see in your file Super-djg is that in every SUBCASE relevant to SEs, there are three METHOD actually identical each other: do I need to repeat this instruction in order the analysis to work? Do I need to include an SPC as well, even if it doesn't change?

As far as damping is concerned, I was thinking to use SEDAMP (and PARAM,SEDAMP,YES) for SEs subcases, pointing to each damping table (see annex).

Please note theat there is also Case 01131684: "sine analysis with multiple SE and different damping".

Thanks in advance and regards,

Stefano.
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0 stefano.fabbri 11 months ago
Dear all,

I'm really interested in the approach you followed, but not sure if applicable to my case.

I need to perform a sine analysis where some external superelements have higher damping wrt to residual structure.

I also need to deliver a reduced model (again, by external SE) form the previous one.

It is very likely that before final delivery, we need to perfom sensitivity analyses changing the damping value

Therefore I want to apply it "externally" to SEs in the residual run.

In theory I should :

create a SUBCASE for every SE using SUPER instruction assigning damping value: as damping is additive, proper values shoud be chosen wrt residual damping to avoid overdamping for SE;

create residual SUBCASE with nominal inputs.

What I see in your file Super-djg is that in every SUBCASE relevant to SEs, there are three METHOD actually identical each other: do I need to repeat this instruction in order the analysis to work? Do I need to include an SPC as well, even if it doesn't change?

As far as damping is concerned, I was thinking to use SEDAMP (and PARAM,SEDAMP,YES) for SEs subcases, pointing to each damping table (see annex).

Please note theat there is also Case 01131684: "sine analysis with multiple SE and different damping".

Thanks in advance and regards,

Stefano.
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