Pretension with Slide and Freeze Surfaces
Altair EmployeeHi, I have to do a NormalModeAnalysis of an assembly. At all there are 11 parts, 4 of them are srews that are pretensioned. There is also a static load and I want to consider that some parts move under this load (small displacement).
With PretensionManager I took under account pretension and with AutoContact I create Surface-Surface Contacts (some freeze, some slide).
My pretension LoadStep is non-linear quasi-static with NLPARM. If I run the Analysis it stops with different error Messages depending on what i have given in NLPARM.
Is my Setup right for what I want to do and if it is what is the Problem? I have never done this in OptiStruct but know it from SolidThinking.
Answers
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Wow! so much contact pairs are in your model!=)
it's not good model for first issue=) you should do some simple test at first=)
i will check this, but i am newbie in optistruct. )
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force direction is incorrect=)
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Hi, colleagues!
why does not increment increase?
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Hi Mrt, thank you for your interest.
Which Force do you mean? A Pretension Force?
There is also a static load in negative z-direction, that is right
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Altair Forum User said:
Which Force do you mean? A Pretension Force?
There is also a static load in negative z-direction, that is right
i don't know. i haven't had experience for pretension in optistruct.
i have tried to change direction, but i had the same result. solution goes, but result i don't like.
do you mean that we can't choose preload force direction?
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It is possible to choose the orientation in Pretension Manager but I think it is set on the normal pretension of a bolt or screw by default...
If I use a linear static load step the results are not useful, it shows me only one screw if I select displacement.
What is your Setup in the second post?
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Hey!
i have an idea!
i will check it.)
try to off static load=) to my mind you shoul switch on it on second step=) Forces apply together, although this is wrong way. )
i will check it too!=)
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Yeah!
pretension works properly!
create another step and move static load.=)
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Do you run it with or without non-linear quasi-static LoadStep?
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Sorry, I can not unzip such files. Can you uploud only the .h3d file? Thank you very much!
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I checked the file but stops because there is no convergence if the Loadstep reaches 1... what is the reason for that?
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i don't know.
maybe you should update your version=)
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I got it, the Problem was the Error tolerance for displacement, I flaged it out and the Analysis runs.
Thank you very much for your help Mrt!
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welcome=)
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Altair Forum User said:
I got it, the Problem was the Error tolerance for displacement, I flaged it out and the Analysis runs.
Thank you very much for your help Mrt!
Hi too much deviation from error tolerance may result is unexpected results. Try to keep it in limits.
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