Stress Constraint at Topology Optimization

Peter_TRH

Hi all, 

 

can someone please explain to me the difference between defining the stress constraint via DTPL - Card and by DRESP1-card?

All the tutorial models show differerent solutions without explaining the difference in detail. 

Thanks in adance!!

 

Regards

Peter

Simon Križnik

Hi,

 

Stress constraint is not recommended in the design concept stage: topology, topography and free-size optimization.



The stress constraint definition in a topology optimization is a global constraint and does not target local stress concentrations.  These areas can be addressed subsequently through size, shape, and free shape optimization or a combination thereof.  Artificial stress concentrations are filtered out during topology optimization with stress constraints.  These include regions around rigid connections, concentrations due to hard geometric features such as corners, etc.

 

Stress constraints for a partial domain of the structure are not allowed because they often create an ill-posed optimization problem since elimination of the partial domain would remove all stress constraints.  Consequently, the global stress constraint applies to the entire model when active, including both design and non-design regions. Stress constraints may not work well in a model where there is a large differential in response values between design and non-design spaces. In these cases, it is recommended to modify the problem formulation to say, compliance based for example. It is not recommended to use the global stress constraint along with a mass/volume constraint. The constrained mass/volume may not allow the stress constraint to be satisfied.

 

DRESP1-card stress constraint is used in subsequent design fine-tuning stage such as size, shape and free shape optimization.

Peter_TRH

Hi, 

 

thanks for your quick reply.

The global stress constraint you are talking about..is the 'DTPL-constraint' right?

 

What exactly to you mean with: 

a large differential in response values between design and non-design spaces ?

 

Thanks

Simon Križnik

Hi,

 

 

Altair Forum User said:

The global stress constraint you are talking about..is the 'DTPL-constraint' right?

 

yes

Altair Forum User said:

 a large differential in response values between design and non-design spaces ?

 

a large difference (range) in stress values between properties declared in the design variable (DTPL) and other properties.