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Elvis

Contact Penetration

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Hello,

 

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.

card.jpg

penetration.jpg

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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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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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On 21.7.2017 at 11:21 AM, Prakash Pagadala 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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39 minutes ago, Prakash Pagadala 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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On 25.7.2017 at 10:02 AM, Prakash Pagadala 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,.. :wacko:

 

I used LGDISP this time to check the behavior but the analysis is still ON...

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3 hours ago, Prakash Pagadala said:

Hi Elvis,

 

Its been almost 18hrs and the analysis is stil running,.. :wacko:

 

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.

pin_lug_update.hm

pin_lug_update.h3d

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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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3 hours ago, Prakash Pagadala 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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4 hours ago, Prakash Pagadala 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?

 

 

Unbenannt.JPG

Unbenannt1.JPG

Unbenannt2.JPG

Unbenannt3.JPG

Unbenannt4.JPG

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7 minutes ago, Prakash Pagadala said:

Hi,

 

Can you post a picture of contact definition?

 

It's similar to the previous one. I activated Large Displacements as well.

Unbenannt5.JPG

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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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19 minutes ago, Prakash Pagadala 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 :D. And no, there are no shell elements in the model.

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22 hours ago, Prakash Pagadala 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?

 

 

aa.JPG

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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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1 minute ago, Prakash Pagadala 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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