Card that relates design variables

Joao_21860

Hello everyone,

 

I am running composite size optimizations and I came across a problem. I need to relate the thickness of different design variables (plies), however, there are no constraints available that address this issue.

 

Is there any CARD that allows me to create such a constraint?

 

*actually, the dependent design variables should be in a specific thickness range (e.g., 0.5t<t1<t), where t is the thickness of the 'main design variable' and t1 the other design variables.

Adriano_Koga

for size optimization problems you could create dervar links combining 2 or more design variables, by creating some relation using them.

with desvar link you could say for example: t1 = 2*t2

It can be created as DESVAR LINK1 or 2.

1 is linear relation, and 2 you can create an equation using DEQUATN. Try looking at them in the Help for OptiStruct.

 

The other way of performing this kind of relation is though a design constraint, just like any other optimization constraint.,

You can create a response of type 'function' (DRESP2) and assign it with an equation (DEQATN).

Then you assign the design variables? (t1, t2, t3...) and create an expression, such as 'F(t1,t2)=abs(t1-t2)'.

Having this relation you could specify a dconstraint and limit the difference to some value, using upper or lower bounds.