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Prescribed Displacement in one direction

Posted Mar 6, 2015, 3:56 a.m. EST Structural Mechanics Version 4.4 4 Replies

Andre Müller
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Dear Comsol-Users,

is it possible to prescribe a displacement only for the positive or negative part of one direction? In my Model an ontop metallization will induce thermal stress which leads to a deformation of the underlying substrate. But due to the poor adhesion of an additional intermediate layer in reality only stress with a negative sign in y-direction (2D-case) will lead to a deformation of the substrate. Now I wonder how to vanish the positive parts during the calculations?

Any ideas?

THX in advance,
André
4 Replies Last Post Mar 6, 2015, 10:11 a.m. EST
Henrik Sönnerlind COMSOL Employee

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Posted: 10 years ago Mar 6, 2015, 4:55 a.m. EST
Hi,

It seems to be essentially the same question as in

www.comsol.com/community/forums/general/thread/63221

The most straightforward way is to introduce Contact pairs between the layers.

Alternatively, you could use a Thin Elastic Layer with compression-only stiffness, but that may not converge well. In practice you would need some small stiffness in tension too, and a smooth transition.

Regards,
Henirk
Hi, It seems to be essentially the same question as in http://www.comsol.com/community/forums/general/thread/63221 The most straightforward way is to introduce Contact pairs between the layers. Alternatively, you could use a Thin Elastic Layer with compression-only stiffness, but that may not converge well. In practice you would need some small stiffness in tension too, and a smooth transition. Regards, Henirk
Andre Müller
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Posted: 10 years ago Mar 6, 2015, 6:00 a.m. EST
Thanks Henrik for your quick answer and your suggestion. However, I tried to define contact pairs, but without success. There is no selectable boundary. Do you know a tutorial which explains how to introduce such a contact pair?

Maybe you want to have a look to my model. The contact pair has to be defined between the two lower rectangles.

Thanks a lot and best regards,
André
Thanks Henrik for your quick answer and your suggestion. However, I tried to define contact pairs, but without success. There is no selectable boundary. Do you know a tutorial which explains how to introduce such a contact pair? Maybe you want to have a look to my model. The contact pair has to be defined between the two lower rectangles. Thanks a lot and best regards, André

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Henrik Sönnerlind COMSOL Employee

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Posted: 10 years ago Mar 6, 2015, 9:54 a.m. EST
In order to use Contact, you must use Form Assembly at the end of the Geometry sequence, so that the domains are not 'glued' to each other.

For examples of contact modeling, go to Model Libraries (in the File menu, for example). Search for "contact", and look at the results under the Structural Mechanics folder.

A Thin Elastic Layer can be used both on an internal boundary and on an assembly.

Regards,
Henrik
In order to use Contact, you must use Form Assembly at the end of the Geometry sequence, so that the domains are not 'glued' to each other. For examples of contact modeling, go to Model Libraries (in the File menu, for example). Search for "contact", and look at the results under the Structural Mechanics folder. A Thin Elastic Layer can be used both on an internal boundary and on an assembly. Regards, Henrik
Andre Müller
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Posted: 10 years ago Mar 6, 2015, 10:11 a.m. EST
You are right. I found how to define Contact Pairs together with Form Assembly, but than the stress of the top layer will not effect the bottom layer. Therefore I will try Thin Elastic Layer.
You are right. I found how to define Contact Pairs together with Form Assembly, but than the stress of the top layer will not effect the bottom layer. Therefore I will try Thin Elastic Layer.

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