composite free size optimization
Altair EmployeeHallo everybody.
I want to run a free size optimization with Optistruct. My model is an Formula Student Monocoque. Everything is ok until I set the optimization. I have got 9 loadcases. One of them is pure torsion. Now, that´s what I have done so far.
- I set the design variable 'free size'
- I set a response static displacement and took two nodes (dof 3) with an dconstraint, lower an upper bound and all loadsteps
- I set a response mass with an objective min
I set the cards:
- PARAM, in_rel=-2
- GLOBAL_OUTPUT_REQUEST: CSTRAIN and CSTRESS
- OUTPUT: FSTOSZ
I set opticontrol:
- DESMAX= 80
- OBJTOL= 0.005
- DELTOP= 0.5
The Check is ok, but when I start an optimization there is an fatal error after about 20 minutes.
INFEASIBLE DESIGN
Then I tried to make an new response.
The displacement response only with the loadstep with the pure torsion and another response with composite failure and the other eight loadsteps. But the free size card don´t support that response. The check and optimization .out files are attached.
FInaly my question. Is there any way, how I can fix it. Or another way I can run an optimization?
Thanks for your help
Answers
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Hi Erik,
looks like there is a problem with constraints in your model.
Please re-create all constraints. If that doesn't work, share the model with us.
to share the model, use the dropbox link in my signature.
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Thank you for your quick response.
I don´t use any constraints. I use the PARAM card with inrel= -2. I have sent you a massage with the attached model.
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Hi Erik,
I had a look at your model.
There are duplicate elements in your model and few elements are overlapping.
Please check this.
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Hallo Prakash,
I checked the elements and delited the duplicate and the overlapping ones. Unfortunately the error is still exsiting. The same as before. The check is ok, but when I run the optimisation there is the error 'INFEASIBLE DESIGN'. Or should I constrain nodes 30109 ans 40109?
Can you take another look at my model? I attached the new model. I´m happy about every type of help.
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Hi Erik,
I will have a look at your model and will get back to you soon ASAP!
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Hi Erik,
Few plies doesn't have material applied.
can you please check PLY 56-66 and apply material to the plies?
Also, check for free nodes in your model. Specially where you have 1D elements,
goto Tools page>> Edges>> select components/elements>> equivalence.
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Thank you very much Prakash!
The optimization is running now. But the results of the optimization questianable. At first I had the Problem that the max displacement and max stresses are ok for first 5-7 iteration. Then the displacement goes up to over 100 and the stresses over 1000. I changed my responses and my constraints, but the results are still questinable.
Can you have another look at my model an check if I made a mistake? I think the model is ok, but maybe the response, objective or constraint is wrong.
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Hi Erik,
Thanks for sharing the file.
I will have a look and I will get back to you soon
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Hallo Prakash.
Did you had a look at the model yet? I really need an answer and I don´t find a sollution for the problem by myself.
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Hi Erik,
Yes, While running I have errors coming up with DSIZE and manufacturing constraints.
Trying to fix them up to make it more feasible.
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Can you tell me what is wrong with my manufacturing constraints and my DSIZE? Is it possible to constraint the loadsteps in two different static displacement constraints? Or is there something like composite failure wich I can use to constraint my first 8 loadsteps? I want to constraint the last one by static displacement? I treid a lot and nearly changed everything, but I don´t get good results. It is really important that I run the optimization. I´m sorry that I have to annoy you so long with that.
Thank you for your help!
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Hi Erik,
Okay, the error I got is because one of the plies (ply 55) is hidden and the same ply is referred in DSIZE in the .hm file. I changed the status but when I export the hm file to .fem it keeps on writing and ends up with a file size of more than 10GB some how.
is it possible for you to share the .fem file to me so that I can run and check the results.
Regarding your question 'Is it possible to constraint the loadsteps in two different static displacement constraints?' Do you want to use two different displacement constraints on same loadsteps, please explain?
You can use composite failure as a constraining response.
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Hi Prakash.
I changed some things in the model. Now there are no hidden Plys anymore. I uploaded the model as .fem file to your dropbox.
Regarding to the loadsteps. I have 9 loadsteps in my model. I want to constrain 8 of them by displacement with 3.5mm. The ninth loadstep is only for torsion. I want to constrain it by an other displacement constrain with 2.8mm. It is important that the ninth loadstep is constrained by displacement. The other 8 could also been constrained by any other type. Do you have an idea if there is an other type of constrain that I could take?
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Hallo Prakash.
Now I ran the free size optimisation and I get really good results. Thank you again for your help. But now I want to export the ply-shape of the plys and I don´t know how to do it. I want to export the different ply shapes to solidworks (as a .step) to edit them. Can you tell me how to do that? I don´t find anything in the online help or the support forum.
Thank you for your help
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Hi Erik,
use the below script to export plies to stp format from http://www.altairhyperworks.com/Script-Exchange.aspx
<?xml version="1.0" encoding="UTF-8"?>
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Dear Prakash,
I would like to export my shuffled optimalized plys too but I can not open the script. This option possible just for the 'elite' user? Or how I can do it?
Thank you very much!
Tibor
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Hi Tibor,
Please refer to the following link:
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Also, if you load the Aerospace Engineering Solution user profile in HyperMesh, this will make the Aerospace toolbar appear.
In that toolbar there is a tool called 'Ply Geometry Smoothing'. A very nice tool to export smoothed ply shapes to step format.
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