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Hello,

 

I'm trying to run a topology optimization on a 3D volume meshed with tetra elements.

the objective is to minimize the Weighted Compliance.

The responses I've chosen are :

- weighted compliance

- Vol Frac

 

the constraints are :

- VolFrac <0.1

- max stress < 870 MPa (via STRESS input in the DTPL card).

 

I get the following error message:

" *** ERROR # 320 ***
 Static load case 1 has prescribed displacements.
 The combination of global stress constraints and prescribed displacements
 is not meaningful. Optimization cannot be performed."

 

I hardly see why it is not meaningful to use global stress constraints with SPCD...

 

does anybody have a solution?

 

Note: the SPCD is applied on a single node which is connected to the volume using a RBE2. Do I have to remove the area close to the RBE2 from the design volume?

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Sorry, it is clearly written in the User Guide: "Stress constraints may not be used when enforced displacements are present in the model."

I have to find another way to "express" the optimization problem without using stress constraints.

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Hi

could you please tell me how you solved the problem? I'm getting the same error but I think I don't have any prescribed displacements in my model. I'm also using weighted compliance and vol Frac as responses. The optimization is running but as soon as I set a max stress I'm getting this error.

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Hi,

 

Try withtout stress. Infact, stress constraint is not recommended. 

 

There are few recommended optimization problem setups available in OptiStruct FAQs. Go through that and setup your problem accordingly :)

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