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Perform two topology optimization (one after the other)

Altair Forum User

Dear Sir or Madam,

I am trying to perform two consecutive topology optimizations.

I have a big model and the first optimization is to have a first reduction of the design space. The second would be to have a more precise result (also by using the feature 'mindim/maxdim' in the 'parameters' of the topology optimization settings.

I tried to incorporate everything in a single optimization but the result is not good. That is why I am trying to divide into two steps.

How should I do that?

I tried with Ossmooth but errors always show up.

Is there an other way? Or should I build a new model with a CAD software and then export it and optimize it?

Thank you in advance

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Altair Forum User

Hi @Mike30

What errors did you encounter with OSSmooth? Please let us know and we will see how we can help you.

One other way is:

You can export the desired topology from HyperView into .stl format and you can finetune the topology in any CAD tool. Use Export>> Solver Deck>> .stl file format

Altair Forum User

While Ossmooth I get the error in the image 'error'.

While when reanalyse the model I get the error in image 'error-2'. Is that because I do not have any solid after the ossmooth?

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

Hi Mike,

Looks like you have interface regions in your model. If the design space is a part of interface region elements maynot be remeshed properly.

You can make elements of interface region as non-design and try again.

Or, you can export as .stl from HV and recreate model again,,

Altair Forum User

Hi,

What do you mean with interface region element? And how to avoid the design space to be part of the interface region?

Second question: after Ossmooth (ISO Surface) the model is not a solid correct? is it possible to make it a solid and not just have the elements?

Altair Forum User

Mike,

What do you mean with interface region element? And how to avoid the design space to be part of the interface region?

I mean contacts in your model

Altair Forum User

Ok thank you.

I managed to run the optimization by setting in the OSSmooth parameters settings 'attached layers' : 2.

Can you tell me what the 2 layers represents?

<?xml version="1.0" encoding="UTF-8"?>

Altair Forum User

An other question:

Is it possible to remesh the model after ossmooth?

I had solid part before the optimization, but after ossmooth there is not any solid.

And the mesh is currently really not appropriate.

Thank you

Altair Forum User

Hi Mike,

Sorry for a late response.

Yes you can mesh the model after OSSmooth. But you may have to apply loads and BCs again if they are affected.

Altair Forum User

Hi,

But how can I remesh the model? Because I do not have solids but only iso surfaces, and if I delete the existing elements after ossmooth I can not select the body because there is not a body but only elements.

The question is, how to transform the elements after ossmooth into solids?

Altair Forum User

Hi Mike,

You can extract surface and remesh the entire component or export the iso surface to any CAD format and refine the topology and mesh it again.

Or,

You can use the existing 2D elements to create tetra elements using 3D>> TetraMesh. Hexa will be very difficult.

Altair Forum User

What happen if I extract the surfaces? How can I do that?

I want to delete the existing mesh on the surfaces and recreate a better one as the dimension I want.

Altair Forum User

Hi Mike,

If that is case then you better export the model to any CAD format where you can refine the geometry using professional CAD tools. When you are happy with new topology, remesh the model and apply the loads and Bcs.

You can export CAD from OSSmooth. Instead of Reanalysis, make it to Geometry.