Assumptions and applications
===========================




Assumptions and limitations
-------------------------

The shell-beam connection is described here, which is used to connect two meshes, one comprising shell (or plate) elements, the other comprising beam elements. This feature makes it possible to model a slender structure in two parts: one part meshed with conventional beam elements, representing the kinematics and behavior of beams, and the other part meshed in shell elements, to reveal other phenomena (ovalization, swelling, localized plasticity).

However, the following assumptions are made:


* the area of the cross section of the end of the shell mesh is identical to the area of the right section of the beam element that corresponds to it,


* the centers of gravity are the same,


* the sections are flat and coplanar,


* The normal to the shell section coincides with the axis of the beam.

Limitations:


* the ovalization of straight sections is not taken into account in the connection,


* warping is not taken into account.




Targeted applications:
---------------------




Piping modeling
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

One of the major applications concerns pipes. The bent parts or the stitches are then meshed into shells, which makes it possible to reveal ovalization, local elastoplastic behavior or swelling in the event of internal pressure. This connection does not transmit the ovalization of the pipes since this ovalization is not modeled in the beam elements. To do this, it is necessary to use the shell-pipe connection or to mesh a sufficient length of straight pipe into shell elements so that the ovalization at the level of the connection is negligible.


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+ .. image:: images/Object_1.svg                                                   + .. image:: images/Object_2.svg                                                   +
|    :width: 255                                                                   |    :width: 357                                                                   |
+    :height: 50                                                                   +    :height: 65                                                                   +
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**Piping with a circular (or rectangular...) cross section meshed into a shell and then into a beam.**




Beam plate connection
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Plate-beam connection (thin rectangular section).


.. image:: images/Object_3.svg
    :width: 255
    :height: 50


.. _RefImage_Object_3.svg:




Symmetric profile beam
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Symmetric profile girder partly meshed in shells.


.. image:: images/Object_4.svg
    :width: 255
    :height: 50


.. _RefImage_Object_4.svg:




Application of a load or "beam" boundary conditions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

At the end of a slender structure meshed into shells, it is often useful to impose either a loading of the "beam" type, i.e. a force twister, or boundary conditions (embedment) compatible with beam kinematics. It is then possible to connect the transverse end section of the shell mesh to a discrete element to which this torsor or this embedment will be applied.




Application not envisaged:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This feature does not allow you to model the "transverse or orthogonal stitches" of a beam on a plate or a shell:


.. image:: images/10000554000051A600002D2A3D1C7392395C38AF.svg
    :width: 255
    :height: 50


.. _RefImage_10000554000051A600002D2A3D1C7392395C38AF.svg: