Error 557 while doing thermal compliance optimization DRESP2 3 is not referenced above the first SUBCASE.

Hello good people,

I am getting the error.

*** ERROR # 557 ***
DRESP2 3 is not referenced above the first SUBCASE.
This type of response must be specified above the first
SUBCASE.
This error occurs in DESOBJ 3.

can you please tell me how to fix this from the graphics window? I was not able to select any loadstep while setting Minimizing thermal compliance optimization!

I am attaching my FEM file

Again can anyone tell me some directory where I can find any tutorial for thermal compliance optimization?

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Rahul Rajan_21763

Can you please use the latest HyperWorks Desktop 2017.3 along with OptiStruct 2018 version (hotfix:2018.0.1)

It seems this was the known issue in older version of 2017 which was fixed in HyperWorks Desktop 2017.2.PFA screenshot from release notes known issue list.So please make sure to use latest version.

Once you submit OptiStruct run please always monitor .out file for any warning/error and act accordingly. For your shared file I would suggest below points:

Its good to have design and non design(loads and boundary condition) region for topology optimization.
It seems material units MAT1 and model units are not consistent. I scaled pipe with 1000 unit to attain 800mm length.
As per the warning mentioned in out file I used mindim in DTPL card.

Please refer sample deck.

<?xml version="1.0" encoding="UTF-8"?>

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Divan.46

Thanks a lot rahul.

Point 1: The case is that thermal compliance must be assigned to a linear heat transfer subcase. I could solve the issue by editing the .fem file in text editor and then putting the DRESP2 3 after the heat transfer SUBCASE. But I am getting negative thermal compliance!

Point 2: Can you please let me know how to make the material units MAT1 and model units consistent?
I mean what about the model unit? I knew hypermesh is non-dimensional.

While loading your .fem file (the one you corrected) I got this warning!

Warning: Unsupported cards found in the I/O options section have been written as unsupported control card.
Summary: Feinput finished with 0 errors and 1 warnings.

<?xml version="1.0" encoding="UTF-8"?>

Rahul Rajan_21763

Point 1 : Please share the .out of the run.

Point 2 : The units are not the same as for thermal conductivity in material properties! They are actually the same as for Heat Transfer Coefficient (H) - exemplary units: W/m²°K, generally: rate of heat transfer per unit area per unit degree of temperature)

You can ignore the warning which is coming for the usage of unsupported bulk card.

Divan.46

Thanks a lot, rahul. I am really grateful to you.

I could solve the error 557 subcase problem by editing the .fem file in a text editor and then reopen it. everything works fine then.

I can do 3D optimization by differentiating design and nondesign space. but in case of 2D optimization 'how to impose CHBDYE surface for heat flux and then optimize that domain? '

I have searched the forum and got a solution like this,
QBDY1 load has to be applied to the slave conduction elements. And two cards '
needs to be defined (OPTI_DEBUG and CASE_UNSUPPORTED_CARDS'

How to do that? can you please help me once again with that? Thank you in advance.