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Modal Frequency optimization

Hello everyone,

I am trying to do an modal frequency optimisation using topography. I am getting the following error. Please help me out. I updated the version to 2017.2 but still I get the same error.

ERROR: The SUBCASE ID in ATT1 field of DRESP1 2 does not refer to a modal FRF subcase.

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Altair Forum User

Hi Punith,

This is a know issue.

The work around is to create DREPS1 FREQ via Entiy Editor nor through panel

or don't select the load step while defining response.

Punith

Hi Prakash,

the problem was not resolved in the tutorial file also. I have attached both model file and .fem file of the tutorial. Can you check it out?

Thanks and regards,

Punith

Unable to find an attachment - read this blog

Punith

The problem was solved thank you.

Altair Forum User

Hi Punith,

Please try this file

Unable to find an attachment - read this blog

Altair Forum User

The problem was solved thank you.

Punith,

Glad to know that the problem is solved /emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20'>

Punith

Hi Prakash,

I have one more question to you. I want to constrain my mode 1 frequency to 300 Hz and at the same time I want to optimize my stiffness of the model. I just have modal frequency subcase in my model and I want to run an topography optimization with the generation of beads. How can I do it? Because to set the compliance as my objective function we need the static loads right?

Thanks,

Punith

Altair Forum User

Hi Punith,

yes you cannot have compliance or displacement responses for Eigen value problems.

As a workaround try this: Use mimimize mass and constraint the frequency. Check if this helps.

Punith

Hi prakash,

it is working. Thank you so much. Now final step it to achieve the symmetric beads on the surface of the cylinder. How do I do that using pattern grouping?. I have attached the image similar to my model. Can you please mark the anchor point, first point and second point in the image? I tried with 2d radial method as I had 2D shell elements wit assigned thickness, but is not working for me.

Thanks and regards,

Punith Guptha

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

Altair Forum User

Hi Punith,

not sure what kind of structure you have, but can you try with cylindrical type constraint?

Punith

Hi,

I already tried with cylindrical pattern grouping, it is trying to change the contour of the cylinder. But I would like to have some beads on the surface of the cylinder with out changing the contour of the cylinder. You can assume my model to be a simple cylindrical pipe as in the image.

Regards,

Punith

Altair Forum User

Punith did you try with 3 pln symmetry?

Please try that and let us know if that does not help can you try with cyc rad type grouping?