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Contact Pairs in Solid Mechanics

Posted Nov 2, 2012, 7:07 a.m. EDT Structural Mechanics Version 3.5a, Version 5.0 5 Replies

phibo
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Hello,

I'm implementing a model about a sphere of a linear elastic material being squeezed between two plates (lower plate rigid, upper plate moving downwards).

To consider the deformation of the sphere, I tried to define contact pairs at the upper (respective lower) pole of the sphere. These contact pairs are defined in the Model - Definitions - section of the model tree, but can not be exploited in the boundary conditions section of the Solid Mechanics section.

Is the possibility of a contact pair boundary condition simply not implemented, or is there any additional issue to consider?

Thanks in advance and regards
pwb
5 Replies Last Post Dec 9, 2015, 3:36 a.m. EST
Erik Bornhöft COMSOL Employee

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Posted: 1 decade ago Nov 6, 2012, 3:36 a.m. EST
Dear phibo,

to do a contact analyses you will need to change the final operation in the geometry-node from "Form Union" to "Form Assembly". This will leave the domains unconnected. Otherwise, when using "Form Union", all interior boundaries will be considered as "Continuity"-condition.
Second you have to define a "contact pair" in "definitions" or let COMSOL do this automatically for overlapping boundaries (choose this option in "Form Assembly").
Third you need to add the actual boundary condition in your structural mechanics node by rightclicking on "Structural Mechanics" > Pairs > Contact. By rightclicking on "Contact" you can also add friction to that contact pair.

See model library entry "Cylinder Roller Contact" as a reference.

--
Hope that helps!

Best regards,
Erik

*********************
Senior Technical Sales Engineer
COMSOL Multiphysics GmbH
Berliner Str. 4
37073 Göttingen
Germany
Dear phibo, to do a contact analyses you will need to change the final operation in the geometry-node from "Form Union" to "Form Assembly". This will leave the domains unconnected. Otherwise, when using "Form Union", all interior boundaries will be considered as "Continuity"-condition. Second you have to define a "contact pair" in "definitions" or let COMSOL do this automatically for overlapping boundaries (choose this option in "Form Assembly"). Third you need to add the actual boundary condition in your structural mechanics node by rightclicking on "Structural Mechanics" > Pairs > Contact. By rightclicking on "Contact" you can also add friction to that contact pair. See model library entry "Cylinder Roller Contact" as a reference. -- Hope that helps! Best regards, Erik ********************* Senior Technical Sales Engineer COMSOL Multiphysics GmbH Berliner Str. 4 37073 Göttingen Germany
phibo
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Posted: 1 decade ago Nov 6, 2012, 5:06 a.m. EST

Dear phibo,

to do a contact analyses you will need to change the final operation in the geometry-node from "Form Union" to "Form Assembly". This will leave the domains unconnected. Otherwise, when using "Form Union", all interior boundaries will be considered as "Continuity"-condition.
Second you have to define a "contact pair" in "definitions" or let COMSOL do this automatically for overlapping boundaries (choose this option in "Form Assembly").


Dear Erik,

thanks, I have done so. I have had a look at the other threads about problems with contact pairs and found about the difference between Assemblies and Unions regarding the definition of pairs. Unfortunately, this didn't help solving my problem either, because...


Third you need to add the actual boundary condition in your structural mechanics node by rightclicking on "Structural Mechanics" > Pairs > Contact. By rightclicking on "Contact" you can also add friction to that contact pair.

See model library entry "Cylinder Roller Contact" as a reference.


... exactly this was my problem, the option "Sol. Mech." > "Pairs" > "Contact" was not available in the menu. Yesterday I contacted support about this, and learned that the solid mechanics I can use in my version of Comsol is not the Solid Mechanics package, which I would have to buy and install first.


--
Hope that helps!

Best regards,
Erik


In some respects, it did help, so... thank you a lot.

Regards
pwb
[QUOTE] Dear phibo, to do a contact analyses you will need to change the final operation in the geometry-node from "Form Union" to "Form Assembly". This will leave the domains unconnected. Otherwise, when using "Form Union", all interior boundaries will be considered as "Continuity"-condition. Second you have to define a "contact pair" in "definitions" or let COMSOL do this automatically for overlapping boundaries (choose this option in "Form Assembly"). [/QUOTE] Dear Erik, thanks, I have done so. I have had a look at the other threads about problems with contact pairs and found about the difference between Assemblies and Unions regarding the definition of pairs. Unfortunately, this didn't help solving my problem either, because... [QUOTE] Third you need to add the actual boundary condition in your structural mechanics node by rightclicking on "Structural Mechanics" > Pairs > Contact. By rightclicking on "Contact" you can also add friction to that contact pair. See model library entry "Cylinder Roller Contact" as a reference. [/QUOTE] ... exactly this was my problem, the option "Sol. Mech." > "Pairs" > "Contact" was not available in the menu. Yesterday I contacted support about this, and learned that the solid mechanics I can use in my version of Comsol is not the Solid Mechanics package, which I would have to buy and install first. [QUOTE] -- Hope that helps! Best regards, Erik [/QUOTE] In some respects, it did help, so... thank you a lot. Regards pwb
Erik Bornhöft COMSOL Employee

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Posted: 1 decade ago Nov 6, 2012, 5:41 a.m. EST
Hi!


... exactly this was my problem, the option "Sol. Mech." > "Pairs" > "Contact" was not available in the menu. Yesterday I contacted support about this, and learned that the solid mechanics I can use in my version of Comsol is not the Solid Mechanics package, which I would have to buy and install first.


That is true. Basic structural analyses is already possible without the "Structural Mechanics Module". For contact analyses you need it though. There is a list of all boundary conditions and in which modules they are included on our website:
www.comsol.de/products/specifications/

In your case search (CTRL+F in your browser) for "contact" in:
www.comsol.de/products/specifications/structural-mechanics/

--
Best regards,
Erik

*********************
Senior Technical Sales Engineer
COMSOL Multiphysics GmbH
Berliner Str. 4
37073 Göttingen
Germany
Hi! [QUOTE] ... exactly this was my problem, the option "Sol. Mech." > "Pairs" > "Contact" was not available in the menu. Yesterday I contacted support about this, and learned that the solid mechanics I can use in my version of Comsol is not the Solid Mechanics package, which I would have to buy and install first. [/QUOTE] That is true. Basic structural analyses is already possible without the "Structural Mechanics Module". For contact analyses you need it though. There is a list of all boundary conditions and in which modules they are included on our website: http://www.comsol.de/products/specifications/ In your case search (CTRL+F in your browser) for "contact" in: http://www.comsol.de/products/specifications/structural-mechanics/ -- Best regards, Erik ********************* Senior Technical Sales Engineer COMSOL Multiphysics GmbH Berliner Str. 4 37073 Göttingen Germany
Maizuar Maizuar
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Posted: 9 years ago Dec 8, 2015, 11:10 p.m. EST
Hi Mr. Erik

I am new to Comsol.

I am trying to analyze a simple prestressed steel concrete beam. The beam composed of three materials: Concrete, steel rebars and prestressed steels. I modeled the concrete element as solid physic while steel rebars as truss physic. At this time, I do not know how to model the prestressed steels, So could you please advise me how to that. Many thanks.

Kind regards


maizuar
Hi Mr. Erik I am new to Comsol. I am trying to analyze a simple prestressed steel concrete beam. The beam composed of three materials: Concrete, steel rebars and prestressed steels. I modeled the concrete element as solid physic while steel rebars as truss physic. At this time, I do not know how to model the prestressed steels, So could you please advise me how to that. Many thanks. Kind regards maizuar
Erik Bornhöft COMSOL Employee

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Posted: 9 years ago Dec 9, 2015, 3:36 a.m. EST
Dear maizuar,

for pre-stressed steel you can potentially use a linear elastic material node and add "initial stress and strain" by right-clicking on it (Version 4.x or 5.x).

We have a tutorial model for a concrete beam with rebars (needs geomechanics module for ottosen material model for concrete):
www.comsol.de/model/concrete-beam-with-reinforcement-bars-10440

And there is also a blog entry about the coupling of trusses and solid mechanics:
www.comsol.de/blogs/coupling-structural-mechanics-interfaces/

If you have a license under subscription feel free to send your questions to our support-team using your COMSOL Access Account.

--
Hope that helps!

Best regards,
Erik

*********************
Erik Bornhöft
Senior Technical Sales Engineer
COMSOL Multiphysics GmbH
Robert-Gernhardt-Platz 1
37073 Göttingen
Deutschland

Knowledge Base:
www.comsol.de/support/knowledgebase/browse/900/

COMSOL Blog:
www.comsol.de/blogs/
Dear maizuar, for pre-stressed steel you can potentially use a linear elastic material node and add "initial stress and strain" by right-clicking on it (Version 4.x or 5.x). We have a tutorial model for a concrete beam with rebars (needs geomechanics module for ottosen material model for concrete): https://www.comsol.de/model/concrete-beam-with-reinforcement-bars-10440 And there is also a blog entry about the coupling of trusses and solid mechanics: https://www.comsol.de/blogs/coupling-structural-mechanics-interfaces/ If you have a license under subscription feel free to send your questions to our support-team using your COMSOL Access Account. -- Hope that helps! Best regards, Erik ********************* Erik Bornhöft Senior Technical Sales Engineer COMSOL Multiphysics GmbH Robert-Gernhardt-Platz 1 37073 Göttingen Deutschland Knowledge Base: http://www.comsol.de/support/knowledgebase/browse/900/ COMSOL Blog: http://www.comsol.de/blogs/

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