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Interfacial boundary conditions for structural mechanics module

Posted 6 mars 2013, 00:15 UTC−5 Version 3.5a 5 Replies

Sin Kim
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Hi,

Does any one knows how to impose a continuous displacement boundary condition on an interfacial boundary between two geometries in solid stress-strain module of Comsol 3.5(a).

Kindest regards

5 Replies Last Post 6 mars 2013, 04:53 UTC−5
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 6 mars 2013, 01:30 UTC−5
Hi

first of all, what do you mean by a "continuous displacement BC on an interface boundary" (on a boundary between two (sub) domains ?

if it changes the geometry you would need to consider ALE or DG

--
Good luck
Ivar
Hi first of all, what do you mean by a "continuous displacement BC on an interface boundary" (on a boundary between two (sub) domains ? if it changes the geometry you would need to consider ALE or DG -- Good luck Ivar
Sin Kim
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Posted: 1 decade ago 6 mars 2013, 01:47 UTC−5
Hi Ivar,

Actually I discussed this problem with some structural mechanics researchers but they have used ABACUS to model this kind of a problem. I dont really have idea how to impose this BC at the interface of two geometries in COMSOL (no such options are available in COMSOL at internal boundaries). I mean at the interface the normal displacements must be continuous (sort of a continuity of displacements I guess). In ABACUS they didn't used any ALE or DG or moving mesh techniques it is just a static analysis It has something to do with the boundary conditions at the interface only.

Regards
Hi Ivar, Actually I discussed this problem with some structural mechanics researchers but they have used ABACUS to model this kind of a problem. I dont really have idea how to impose this BC at the interface of two geometries in COMSOL (no such options are available in COMSOL at internal boundaries). I mean at the interface the normal displacements must be continuous (sort of a continuity of displacements I guess). In ABACUS they didn't used any ALE or DG or moving mesh techniques it is just a static analysis It has something to do with the boundary conditions at the interface only. Regards
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 6 mars 2013, 03:14 UTC−5
Hi

But I still cannot understand which equation you want to impose on that boundary, as with COMSOL you can adapt the equations at will, there is no real reason it cannot be done. the question is how easily ;)

But first of all which equations ?

--
Good luck
Ivar
Hi But I still cannot understand which equation you want to impose on that boundary, as with COMSOL you can adapt the equations at will, there is no real reason it cannot be done. the question is how easily ;) But first of all which equations ? -- Good luck Ivar
Sin Kim
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Posted: 1 decade ago 6 mars 2013, 04:02 UTC−5
Hi,

From one of the comsol models (vibration of milk container) in which PDE is used to model the physics, I guess in order to have the continuous normal displacements at the interfacial boundaries we must impose the following equation at the interfacial boundary only.

E_1 n.[u v w]' - E_2 n.[u v w]' = 0 (In the tutorial only one E is used, but I think in my problem I have to use both E (s))

where E_1 and E_2 are the modulus of elasticity of two materials (domains), n is the out ward normal vector and u, v and w are displacements.

Now the question is how can I implement this equation at the interfacial boundary in my problem?

Kindest regards
Hi, From one of the comsol models (vibration of milk container) in which PDE is used to model the physics, I guess in order to have the continuous normal displacements at the interfacial boundaries we must impose the following equation at the interfacial boundary only. E_1 n.[u v w]' - E_2 n.[u v w]' = 0 (In the tutorial only one E is used, but I think in my problem I have to use both E (s)) where E_1 and E_2 are the modulus of elasticity of two materials (domains), n is the out ward normal vector and u, v and w are displacements. Now the question is how can I implement this equation at the interfacial boundary in my problem? Kindest regards
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago 6 mars 2013, 04:53 UTC−5
Hi

why E ? as for me E is the Young Modulus, but here its probably something else ?
In any case the best way to learn how it's done is to look at the underlying equations (I have forgotten in which tab they are in 3.5, check the Forum a few years ago, it has been discussed there)

--
Good luck
Ivar
Hi why E ? as for me E is the Young Modulus, but here its probably something else ? In any case the best way to learn how it's done is to look at the underlying equations (I have forgotten in which tab they are in 3.5, check the Forum a few years ago, it has been discussed there) -- Good luck Ivar

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