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Release rotation edge Shell

Posted 26 oct. 2023, 04:24 UTC−4 Structural Mechanics Version 6.1 2 Replies

Enrico Borellini
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Hello everyone. In the beam module there is the function to release the rotation or translation of the point. For shell elements is there this function to release the rotation around the local axix 1 and keep fixed the other displacement ?

Thank you

2 Replies Last Post 27 oct. 2023, 08:03 UTC−4
Henrik Sönnerlind COMSOL Employee

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Posted: 6 months ago 27 oct. 2023, 02:41 UTC−4

As I understand your question, you want to introduce a hinge along an edge.

There is no built-in feature for that, but it is doable:

First, you need to make sure that the edge is actually two edges, one belonging to the surface on each side. Use Assembly mode for the geometry. Depending on how your geometry is built, you may need to add, for example, a Split node in the geometry sequence. Of course, you need to 'unionize' any other parts that may be disconnected in Assembly mode.

Now, there are at least two possible approaches.

In the first, you add an Edge to Edge feature in the Shell interface, and select Method as Flexible. Then, you enter appropriate spring constants to reconnect the intended degrees of freedom. This is the easiest method, but the selection of the spring constants is not obvious.

Another alternative is to add an extrusion coupling operator to one of the edges. Then, you add a Prescribed Displacement/Rotation node, and set the displacements on the second edge equal to the mapped displacements from the first edge.

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Henrik Sönnerlind
COMSOL
As I understand your question, you want to introduce a hinge along an edge. There is no built-in feature for that, but it is doable: First, you need to make sure that the edge is actually two edges, one belonging to the surface on each side. Use Assembly mode for the geometry. Depending on how your geometry is built, you may need to add, for example, a Split node in the geometry sequence. Of course, you need to 'unionize' any other parts that may be disconnected in Assembly mode. Now, there are at least two possible approaches. In the first, you add an *Edge to Edge* feature in the Shell interface, and select *Method* as *Flexible*. Then, you enter appropriate spring constants to reconnect the intended degrees of freedom. This is the easiest method, but the selection of the spring constants is not obvious. Another alternative is to add an extrusion coupling operator to one of the edges. Then, you add a *Prescribed Displacement/Rotation* node, and set the displacements on the second edge equal to the mapped displacements from the first edge.
Enrico Borellini
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Posted: 6 months ago 27 oct. 2023, 08:03 UTC−4

Thank you for your answer. I'll attach the image for a better question (the red line is my cylindrical hinge). When I have to prescribe a displacement is not a problem, I'll use the global coordinates, but when I have to insert the rotations ? it's very complicated, because I must insert the local rotations along the tangents (t1 and t2). t2 is free, but t1 ? Is there a solution ?

thanks for your available.

Thank you for your answer. I'll attach the image for a better question (the red line is my cylindrical hinge). When I have to prescribe a displacement is not a problem, I'll use the global coordinates, but when I have to insert the rotations ? it's very complicated, because I must insert the local rotations along the tangents (t1 and t2). t2 is free, but t1 ? Is there a solution ? thanks for your available.

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