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Material intersection with heating of hollow tube

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I have a model which contains a thin hollow tube with two walls. I heat material next to wall #1 and want to simulate thermal expansion deforming that side of the tube into contact with side #2. The model I've created does deform wall #1 with the application of heat, but the material does not stop at wall #2. The material from wall #1 continues through wall #2 without displacing wall #2. It is as if the contact and intersection of the material is not registered as a problem.

I've tried both leaving the tube as open space (without a domain) and defining the tube as a separate domain and filling it with air, but neither fixed this issue.

I'm new to COMSOL, and can't imagine that this problem is unique to me, but haven't been able to find a solution.

Any help would be appreciated! Thanks!

3 Replies Last Post 31 août 2016, 11:26 UTC−4
Nagi Elabbasi Facebook Reality Labs

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Posted: 8 years ago 26 août 2016, 10:37 UTC−4
Hi Nate,

You need to define contact interaction between the two walls. The contact algorithm will monitor the distance between the two surfaces and when they overlap a contact force will be internally applied to deform the two bodies until the overlap is eliminated.

Nagi Elabbasi
Veryst Engineering
Hi Nate, You need to define contact interaction between the two walls. The contact algorithm will monitor the distance between the two surfaces and when they overlap a contact force will be internally applied to deform the two bodies until the overlap is eliminated. Nagi Elabbasi Veryst Engineering

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Posted: 8 years ago 28 août 2016, 21:00 UTC−4
Hello Nagi,

Thank you for the quick reply. Am I correct in thinking the only way to define contact pairs is to create an assembly? In the model I would like all other adjacent boundaries to be "glued" together. It seems I have two options with these other interfaces, to create "identity pairs" or use the "Union" Boolean Operation. Are these options equivalent and is one preferred over the other? Some of the boundaries I would like to be "glued" are on the same domain as the boundaries which come into contact.

Cheers,

~Nate
Hello Nagi, Thank you for the quick reply. Am I correct in thinking the only way to define contact pairs is to create an assembly? In the model I would like all other adjacent boundaries to be "glued" together. It seems I have two options with these other interfaces, to create "identity pairs" or use the "Union" Boolean Operation. Are these options equivalent and is one preferred over the other? Some of the boundaries I would like to be "glued" are on the same domain as the boundaries which come into contact. Cheers, ~Nate

Nagi Elabbasi Facebook Reality Labs

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Posted: 8 years ago 31 août 2016, 11:26 UTC−4
Hi Nate,

You don’t necessarily need to create an Assembly. If the parts are initially touching or overlapping then you need an Assembly for COMSOL to keep them separate, and in that case you should define intermediate Union operators to join parts of the model that you want permanently glued to each other. If the parts you wish to contact are initially separate (meaning there is a gap between them) then the final geometry operator can be a Union. In that case you define the contact pair manually in the Definitions section under “Pairs”. I hope that helps.

Nagi Elabbasi
Veryst Engineering
Hi Nate, You don’t necessarily need to create an Assembly. If the parts are initially touching or overlapping then you need an Assembly for COMSOL to keep them separate, and in that case you should define intermediate Union operators to join parts of the model that you want permanently glued to each other. If the parts you wish to contact are initially separate (meaning there is a gap between them) then the final geometry operator can be a Union. In that case you define the contact pair manually in the Definitions section under “Pairs”. I hope that helps. Nagi Elabbasi Veryst Engineering

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