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September 9, 2010 7:59pm UTC

How to model shell element tied together with solid element?

Hello!

I have a problem regarding how to model the solid elements attached with shell elements on the surface.
For example, a cubic modeled with solid element, fixed left boundary, add face loading on the right boundary,
there is a shell layer attached to the right surface of the cubic, for the shell element, fix four edges on the right surface.

Seems it works if I apply some loading on the solid element surface, since the shell elements and solid elements share same nodes, the shell elements will deform with the solid elements.

But the result seems little bit strange, the deformation, the deformation is rather jaggled on the boundary no matter how fine mesh I have.

Attached the model, could anyone give some suggestions? Thanks a lot.
BR,
Li

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September 10, 2010 9:22am UTC in response to Ivar Kjelberg

Re: How to model shell element tied together with solid element?

Hi Ivar,
Thanks for your answer. I noticed that you have some post of a model about coupling shell and solid element.
That's a very good example. But my problem seems little different with that one, this model, the all the shell elements are attached to the solid elements, it's like an out layer on some solid.
Do you have some example models or documents on this.
Thanks a lot for your help.
/Xiaogai

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September 29, 2010 11:23am UTC in response to Ivar Kjelberg

Re: How to model shell element tied together with solid element?

Hi Ivar!

Thanks a lot for your answer. You were right.
But now I have a new problem regarding shell and solid modeling.

As we can see that in comsol version 4.0a, the shell element is Mindlin Reissner shell element with order from 1st order to 2nd order element.

In the model, I use 3rd order for solid element , 2nd order for shell element. Then I will get a "singularity" problem in the model. But if I tried to change shell element to 1st order, then it works. But it looks strange on the boundary.

My question is, why I got singularity problem if I use 3rd order solid, 2nd order shell,
but it did work if I 3rd order solid, 1st order shell element model?

Is this because of the extra nodes for 2nd order shell doesn't share same with 3rd order solid, while 1st order shell always have same node with 3rd order element?
I attached the model in case I didn't express myself clearly.

Thanks a lot.
Xiaogai

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