Topology Optimization in Optistruct - Problem with two loadsteps

Altair Forum User

Hi,

 

 

The problem consists of a connecting rod submitted to axial loads which define the phases of admission (traction) and combustion (compression).

I am trying to run the following optimization:

• 2 load steps :
  • linear static (traction)
  • linear static (compression)
• 2 responses :
  • Volume
  • Compliance
• 1 constraint :
  • 60% Volume
• 1 objective :
  • minimize compliance

 

Without combining the two load steps, I managed to run the optimization.

I couldn't find a way integrating the two load steps for the optimization. I found that the only time that I can include the load step is when I define the objective. However only one load step can be selected. Therefore I was wondering if there is a way to integrate both of the load steps mentioned earlier.

 

Thank you !

Simon Križnik

Hi @Intan

 

Use Minimize Weighted Compliance for Constrained Volume

 

OptiStruct provides the response type WCOMP, weighted compliance, to be defined on the DRESP1 card. In addition, you need to define the weight factors for each load case included in the weighted compliance function. Note that both the objective and constraint are global quantities (not specific to any single load case) and thus the DESOBJ and DESGLB statements occur before the load case declarations.

Altair Forum User

Altair Forum User said:

Hi @Intan

 

Use Minimize Weighted Compliance for Constrained Volume

 

OptiStruct provides the response type WCOMP, weighted compliance, to be defined on the DRESP1 card. In addition, you need to define the weight factors for each load case included in the weighted compliance function. Note that both the objective and constraint are global quantities (not specific to any single load case) and thus the DESOBJ and DESGLB statements occur before the load case declarations.

 

Hi @Ivan

Thank you so much for your reply! I will try to use the method you mentioned.