ERROR 320

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

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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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited December 2015

    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.

  • Felix-Th
    Felix-Th Altair Community Member
    edited January 2016

    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.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2016

    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 :)/emoticons/default_smile.png' srcset='/emoticons/smile@2x.png 2x' title=':)' width='20'>

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