Permissible values for thickness in Topology optimization

rzmehdipour

Hi there,

 

I wanted to know if it's possible to define thickness steps when performing topology optimization using Optistruct. For example assume there is a body of PSHELL elements, Initial thickness is 10 and base thickness is 2.5 and between these two values only 6 is permissible. Or in another case only 8.5 and 2.5 are possible for final part. How can I go with this kind of problems? The real problem is to decrease some deflections of sheet metal parts by adding welded patches so thickness in different regions can not be any value. For example if initial thickness is 2.5 mm then I want to improve strength by only welding some 6 mm thickness patches to it so optimization output must be only 2.5 and 8.5 mm thickness.

 

Please let me know if my question is not clear.

 

Thanks in advance.

Simon Križnik

Hi,

 

try this approach:

• mesh the non-design component and assign 2.5mm thickness
• duplicate the elements into the design component, equivalence nodes (F3) and assign 6mm thickness
• set up topology optimization referencing the design component with 0 base thickness
• to get distinct element densities increase the analysis>optimization>opti control>DISCRETE=2 or 3

Optionally, after interpreting topology optimization results into patches you could perform size optimization to get discrete thickness (DDVAL).

rzmehdipour

Altair Forum User said:

Hi,

 

try this approach:

• mesh the non-design component and assign 2.5mm thickness
• duplicate the elements into the design component, equivalence nodes (F3) and assign 6mm thickness
• set up topology optimization referencing the design component with 0 base thickness
• to get distinct element densities increase the analysis>optimization>opti control>DISCRETE=2 or 3

Optionally, after interpreting topology optimization results into patches you could perform size optimization to get discrete thickness (DDVAL).

 

Thank you very much. By setting DISCRETE to 3 result was much better than the original one and was OK for me. But generally it would be useful if ALTAIR developers make it possible for user to define desired thickness steps for such optimization problems.

 

Simon Križnik

Glad to help. 

 

User desired thickness steps are defined with DDVAL in the size optimization. Something similar can be accomplished by free-size optimization (it is not just for composites). Note however such an approach produces suboptimal results compared to the approach disclosed above.

 

Check out three step optimization tutorial by @Manuel Ramsaier

 

Unable to find an attachment - read this blog

rzmehdipour

Thanks again. 

 

In fact I don't have any previous experience in size optimization. It seems I have to try it.