Contact Penetration
Altair EmployeeHello,
i am simulating a contact (slide) between a pin and a lug. At the beginning of the motion everything is fine, but at the end the pin is penetrating the lug. The pins displacement is implemented with a constraint. I already tried to change master and slave, but it didn't work. I have no idea what to do next, do someone have some hints maybe? I attached a screenshot of my card settings and the movement of the pin.
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Answers
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Hi,
I think the issue is with the contact stiffness.
Can you try with TRACK>>CONSLI in CONTACT card.
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Hi Prakash,
thank you for you quick respond. I can't find this option in my contact card?
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Hi Elvis,
Can you add this manually in the deck and try again?
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I don't know how to do this, can you please explain real quick?
When I switch the option 'DISCRET' in my CONTACT card to 'S2S', then there is a option 'TRACK', but I can only choose 'SMALL' or 'FINITE', there is no 'CONSLI'.
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Elvis,
with Discrete S2S I can see TRACK>>CONSLI.
If you still face the problem, please share the model file.
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Maybe it's because I use HyperWorks 14.0.1? I can't find this option. I attached my file.
Thanks Prakash.
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Altair Forum User said:
Elvis,
with Discrete S2S I can see TRACK>>CONSLI.
If you still face the problem, please share the model file.
Hey Prakash,
did you already take a look at my model?
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Hi Elvis,
Sorry,
Yeah I got the model and i am working on it. Will share feedback ASAP!!
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Altair Forum User said:
Hi Elvis,
Sorry,
Yeah I got the model and i am working on it. Will share feedback ASAP!!
Alright, thanks Prakash.
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Even with finite sliding, I see the same result. I am running a large displacement analysis now. Once the results, I will share the same with you.
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Altair Forum User said:
Even with finite sliding, I see the same result. I am running a large displacement analysis now. Once the results, I will share the same with you.
Hey Prakash,
any results already? I tried a few things too, but unfortunately unsuccessful.
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Hi Elvis,
Its been almost 18hrs and the analysis is stil running,..
I used LGDISP this time to check the behavior but the analysis is still ON...
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Altair Forum User said:
Hi Elvis,
Its been almost 18hrs and the analysis is stil running,..
I used LGDISP this time to check the behavior but the analysis is still ON...
Hey Prakash,
yes I know, I have the same problem too. I updated the model, because I thought it was to stiff maybe, but the contact is working incorrect from the beginning now. I tried to change the SRCHDIS and CLEARANCE Parameters, but don't get good results either. I just want to understand the contact behaviour in Optistruct, but it's totally confusing to me now. Maybe you know what the problem with this model is? I attached the .hm and the .h3d files for you.
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Hi Elvis,
Large displacement worked but did not converge after 99.98% load. So you need to reduce the load by a little bit (say 2-3%) and try again with LGDISP.=1. You can use NLOUT for intermediate timestep results in h3d
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Altair Forum User said:
Hi Elvis,
Large displacement worked but did not converge after 99.98% load. So you need to reduce the load by a little bit (say 2-3%) and try again with LGDISP.=1. You can use NLOUT for intermediate timestep results in h3d
Thank you Prakash, you helped me a lot. But what is the problem with the above mentioned model? The contact is failing here at the beginning already. The deformation is totally unrealistic.
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Elvis,
I think the basic formulation used is wrong. We are working on a large strain problem with small strain formulation which is wrong. Using Large displacement method I am able to see results. I can share the h3d file to you through mail. Since I used NLOUT the run took almost 24hrs
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Altair Forum User said:
Elvis,
I think the basic formulation used is wrong. We are working on a large strain problem with small strain formulation which is wrong. Using Large displacement method I am able to see results. I can share the h3d file to you through mail. Since I used NLOUT the run took almost 24hrs
Hey Prakash,
thanks, you really helped me a lot. I didn't know that the function LGDisp is existing. I am working on a updated model which is not so stiff and where the calculation is executed much faster. I used the same settings like you, but i got some strange deformations here. As you can see, the contact is working very well at the beginning, but in the middle of the motion the components are seperating, which should not happen. Do you know what could be wrong?
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Hi,
Can you post a picture of contact definition?
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Altair Forum User said:
Hi,
Can you post a picture of contact definition?
It's similar to the previous one. I activated Large Displacements as well.
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Hi Elvis,
Everything looks fine with contacts
Are there any shell elements in your model?
Please share the model file using the dropbox link.
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Altair Forum User said:
Hi Elvis,
Everything looks fine with contacts
Are there any shell elements in your model?
Please share the model file using the dropbox link.
Done
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Altair Forum User said:
Hi Elvis,
Everything looks fine with contacts
Are there any shell elements in your model?
Please share the model file using the dropbox link.
Prakash,
I found the mistake. I did not use NLOUT, and when I started the animation I saw this result which I sent you above. Using NLOUT and then switching from Load factor to Load factor in Hyperview is showing me the right deformation, without seperating of the components. This result is satisfying, but I don't understand it. Why is the result dependent of the animation option?
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Hi Elvis,
This is strange. Did you see convergence issues with NLOUT?
What about with NLOUT, did you change anything in NLPARM?
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Altair Forum User said:
Hi Elvis,
This is strange. Did you see convergence issues with NLOUT?
What about with NLOUT, did you change anything in NLPARM?
No I did not change anything. There were no convergence issues. When I change the animation button to 'transient animation' I get the right deformation as well.
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Hi,
Yes when therer are incremental results, it is better to use transient animation. But without NLOUT you did not see right behavior which is strange.
I am going to put this forward to developers.
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Altair Forum User said:
Hi,
Yes when therer are incremental results, it is better to use transient animation. But without NLOUT you did not see right behavior which is strange.
I am going to put this forward to developers.
Ok thanks Prakash.
Another issue. I want to determine the reaction forces at the constraint which is performing the displacement, but it somehow don't show me any results. I activated the GPFORCE button and then tried to show the reaction forces in Hyperview with the option 'derived results', that's how I did it in previous tasks. But I do not get any result with this. The model which you sent me ('PinLug.fem') has the same problem. Any hints?
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