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Strain constraint error in free-size optimization

Hello,

I have done a free-size optimization with a displacement constraint and it has been successfully solved. However the strains are huge and the model fails. I would like to constrain the strains to obtain the optimized model.

Now I have tried to do a free-size optimization with a 'composite strain' constraint and then an error appears. I understand that stresses and strains are related, so I don't understand why this error appears if I have defined a 0.007 maximum strain.

This is the error:

*** ERROR # 1800 ***
Stress/strain/force responses are applied to ply 1 which
belongs to a topology or free-size domain. For stress-constrained
topology or free-size optimization, please use the STRESS option
on the design variable definition card.

This is my Response panel:

1.PNG.efc815bbc211f2ac899f02f32beaa5c7.PNG

This is my Constraints panel:

2.PNG.86addd6182553d0cf1155d37dd1f2dd1.PNG

This is my Design Variable panel:

3.PNG.4cc291aa4d235f1aca583e4ca3ddc176.PNG

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Altair Forum User

Hi @Samuel Caviedes

DRESP1 stress is not supported for freesize or topology optimization problems.

You need to enter the stress constraint on DSIZE itself.

Goto FREESIZE panel>> PARAMETERS>> add STRESS constraint

Altair Forum User

Hi @Prakash Pagadala

I meant 'element strain' constraint. I know they're both related (stress/strain), but it's hard to find 'yield stress' empirically because it's related with the number of plies.

Thanks,

Samuel

Altair Forum User

@Samuel Caviedes

If you are running a three phase composite optimization you can use composite strain as a response during sizing of plies. But during freesize it is not.

Santosh G

I am trying to solve a topology optimization problem with DRESP2 card, mass fraction and stress are defined as responses which are also linked to equation. I am getting an error

*** ERROR # 1800 ***
Stress/strain/force responses are applied to property 50 which
belongs to a topology or free-size domain. For stress-constrained
topology or free-size optimization, please use the STRESS option
on the design variable definition card.

This error occurs in module 'dppdrv1'.

I am not able to understand this error

Please help to overcome this error

Robert Lawson

OS wants you to use the stress option on the DTPL card instead of a DRESP1. However, that means you won't be able to pass that response to your DRESP2/DEQATN. This might be a show-stopper for you.