Simulation Mechanical and Multiphysics

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yasmind
Posts: 23
Registered: ‎02-04-2013
Accepted Solution

bonded contact

375 Views, 4 Replies
04-30-2013 04:47 AM

Hi all,

I am working on a frame model where all my contacts are bonded. But when I run the analysis I see that not all of the nodes on the surfaces that are supposed to be in contact with each other are conded. Please see the attached figures.

Why is this? What is the solution.

Thanks in advance.

best,

yasmind

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*Expert Elite*
AstroJohnPE
Posts: 570
Registered: ‎08-30-2012

Re: bonded contact

05-01-2013 06:17 AM in reply to: yasmind

Hi yasmind,

 

The wireframe image shows approximately 6 elements across the thickness of the top member and 9 elements across the thickness of the bottom member. So apparently only the nodes on these separate size mesh that happen to match are bonded together.

 

The software will normally match the mesh between different parts even if the mesh size is set to be different.

  1. How did you create the mesh?
  2. Did you change any settings before creating the mesh? Or after creating the mesh?
  3. Is there a gap between the parts in the CAD model? (Matched meshes are created only when the gap between parts is 0 or smaller than the tolerance, which defaults to 5% of the mesh size.)
  4. Just out of curiosity, what is the default type of contact? I am wondering why you explicitly set so many contact pairs to be bonded.

I am guessing from the name of the design scenario that you are performing a nonlinear analysis (either MES or Static with Nonlinear Materials). So there are ways to "bond" the surfaces together even if the meshes do not match. This can be done by using surface to surface contact and setting the contact type to "Tied".

 

John Holtz, PE
Mechanical Engineer
Pittsburgh, PA

Simulation Mechanical user since Dec 1997
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Contributor
yasmind
Posts: 23
Registered: ‎02-04-2013

Re: bonded contact

05-01-2013 01:51 PM in reply to: AstroJohnPE

Hi John,

Thanks for your reply. I used automatic meshing option and I don't recall that I changed any options before or after meshing. The default contact type in my current model is bonded and it seems that I specifically bonded all parts together only because I ran the same model with different contact options (and also linearly) before. 

My geometry should be fine (no gaps between surfaces), I don't understand why this problems occured. Thanks for drawing my attention to the meshing, I'll try to re-mesh it or use the tied contact option.

 

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Contributor
yasmind
Posts: 23
Registered: ‎02-04-2013

Re: bonded contact

05-03-2013 08:07 AM in reply to: yasmind

Hi John,

Tied contact option didn't solve my problem, because it does not at all work. My contact surfaces behave as if they are completely free. What can I do?

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Distinguished Contributor
ilyas
Posts: 141
Registered: ‎06-13-2012

Re: bonded contact

05-04-2013 10:02 AM in reply to: yasmind

Hi, I think your problem is mesh matching, if you are not using smart bonding, then you must have the mesh to match for it to be bonded.

 

1. Make sure you have virtual imprinting checked inside the Model tab of the Mesh Settings dialog.

2. If that does't work, you might want to try to reimport the model and perform surface splitting. Basically you would want the nodes to match at the contacting surface of two parts.

3. Unlike surface contact, bonded contact should tell the mesher to match the nodes of the two parts, but if you still have problems, delete the contacts that you specified and just fall back on the default:bonded contact as that usually works for me.

 

Regards

Ilyas

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