Pretensioned Bolts Analysis not working correctly
Altair EmployeeHi,
I want to analyse an engine component that is pretensioned with two bolts and I have two problems with it.
In order to understand how the pretensioning is done I did the tutorial OS-1390.
After doing it I applied the same concept on a simplified model with one bolt only.
My goal was it to pretension the bolt first and continue with a second loadstep with pretensioned bolt. When I Iook at the result the loadcase “pretension” works fine. I can see how the bolt is pretensioned and how the structure is influenced by this behaviour. When I look at the second loadstep I can see that the calculation is not starting with the final state of the first “pretension” loadstep. Instead both loadsteps start from the initial state.
Can you tell me how does this come?
I build up the loadsteps like this:
Loadstep 1: Pretension (non-linear quasi static)
Spc -> spc
Pretension -> Pretens_1
NLPARM -> NLPARM (created Loadcollector with NLPARM Card Image)
Loadstep:2 Loadstep Force(non-linear quasi static)
Spc -> spc
NLPARM -> NLPARM (created Loadcollector with NLPARM Card Image)
Load -> load (created load/ force)
STATSUB(PRETENS) -> Pretension
CNTNLSUB -> checked and YES (tried also SCID)
Basically this is how it is done in the tutorial so I do not get why it is not working correctly. What am I doing wrong?
On top of this I want to do an optimization run where I want to minimize the compliance and to reduce the weight. Therefore I would usually set up the responses “weighted compliance” and “volfrac” with the constraint “0.9” and the objective “min”.
Is it possible to do this optimization run based on the already pretensioned state?
If yes how to do it?
Thank you.
Answers
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Could anyone please help`?
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Hi,
Thanks for sharing file. I wil check and update to you soon.
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how do you see that it is not zero?
Maybe its not viewed correctly.
I attached 3 screenshots.
First one (pretension-end) is the result of the pretension loadstep. Displayed correctly in my opinion.
Second one (loadstep2-initial) is the result of the pretension together with the other loadstep (force) . Shouldn't it look like the first picture in the beginning? I can't see that the bolt is pretensioned already...
Third one (loadstep2-end) shows the final state of both together.
maybe this is just not visualized/displayed correctly?
Please explain how i can be sure that it is realy pretensioned first and gets loaded after?
Thank you!
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
<?xml version="1.0" encoding="UTF-8"?>
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Hi,
I used NLOUT. let me try again and see if the issue is same with NLOUT.
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Hi,
how do Í use NLOUT?
Did you find out anything?
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@Prakash Pagadala Any update on this`? I am still not sure if the pretensioning is working correctly. Thank you.
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We see that this is happening to few model and not for all. We are working with experts on this.
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