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Prateek Gupta

Removing all the material at the final iteration after topology optimization

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I am doing a topology optimization on a Aircraft wing-fuselage lug. And it also optimize the component without any error in its ".out" file. But when I check the results in Hyperview  of its last 20th iteration, it is completely removing my design space material. So should I take the resulted component from 9th or 10th iterative solution or Is it because the stress induced is very less than the max stress constraint applied or I'm doing any thing wrong? Please anyone guide me.

Thankyou

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Hi Prateek,

 

You can consider intermediate results if all constraints and objective. But we recommend to consider final iteration results.

 

Can you check your design and non-design space. Since I don't know about the model or optimization setup I cannot comment on stresses. 

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On 6/5/2017 at 5:17 PM, Prateek Gupta said:

I am doing a topology optimization on a Aircraft wing-fuselage lug. And it also optimize the component without any error in its ".out" file. But when I check the results in Hyperview  of its last 20th iteration, it is completely removing my design space material. So should I take the resulted component from 9th or 10th iterative solution or Is it because the stress induced is very less than the max stress constraint applied or I'm doing any thing wrong? Please anyone guide me.

Thankyou

 

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On 6/5/2017 at 5:26 PM, Prakash Pagadala said:

Hi Prateek,

 

You can consider intermediate results if all constraints and objective. But we recommend to consider final iteration results.

 

Can you check your design and non-design space. Since I don't know about the model or optimization setup I cannot comment on stresses. 

Thank you Prakash, for replying me on my query. Here I have attached the ".hm" and ".fem" file of my component. Can you please check it and tell me what is wrong I had done.

 

 

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Hi Prateek,

 

Please define a optimization constrain on your model. Since there is no constrain and the objective is to reduce model, all the material is removed.

 

Also, as a design variable choose only Design space.

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2 hours ago, Prakash Pagadala said:

Hi Prateek,

 

Please define a optimization constrain on your model. Since there is no constrain and the objective is to reduce model, all the material is removed.

 

Also, as a design variable choose only Design space.

Ohh! Thank you Prakash.. I thought that It would be sufficient to give the max stress value through Analysis>>Optimization>>topology>>parameter only.

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Hi Prateek,

 

In the .hm file you shared there is no stress constraint on DTPL card. can you share the stress constrain value you want to use?

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Just now, Prakash Pagadala said:

Hi Prateek,

 

In the .hm file you shared there is no stress constraint on DTPL card. can you share the stress constrain value you want to use?

stress constraint = 1000 MPa 

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Hi Prateek,

 

I think that is a bit too much to relax for your model. 

 

Can you try with say 200/300 MPa and use Minmeber size and also move the surrounding elements of holes to non-design space. 

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On 6/12/2017 at 4:35 PM, Prakash Pagadala said:

Hi Prateek,

 

I think that is a bit too much to relax for your model. 

 

Can you try with say 200/300 MPa and use Minmeber size and also move the surrounding elements of holes to non-design space. 

Thanks Prakash!
 

It takes a bit of time to run, but works without an error now.

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Hi Prakash,

 

can you guide through a way to use the results from intermediate iterations and use it for reanalysis in ossmooth because in OSSmooth it asks for .fem file as input and it takes the threshold with respect to last iteration only !

I tried exporting the solver deck as .fem file (Nastran/Optistruct format)from an intermediate iteration but without success.However, it is able to export an intermediate design as .stl successfully !

 

 

Regards,

Nipun Dahra

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Hi,

 

Use OUTPUT>> SHRES>> ALL. This will write out .sh files for all iterations. This file can be used in OSSmooth for reanalysis along with master .fem file. 

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