Strain constraint error in free-size optimization

Altair Forum User

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:

 

This is my Constraints panel:

 

This is my Design Variable panel:

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.