Reply To: Solid to Shell issues when sharing topology

[peteroznewman]

Nodes on solid elements have no rotational DOF, while nodes on shell elements do have rotational DOF and as your found, if a surface edge is adjacent to a solid edge, a hinge is the result.

One method to get rotational connection between shell and solid elements along an edge is to overlap the shell with the solid. In your case, the you have the face of the solid rib. In SpaceClaim, it is simple to select that face and type Ctrl-C, Ctrl-V to copy the face and create a surface.  Put that surface in the same component with the surface for the panel which is interior to the ribs.  Use the Share button on the Workbench tab to share topology between those two surfaces.  You can also share topology with the solid body.

In Mechanical, you should be able to mesh the panel and the surface created on the bottom face of the rib with shell elements and also mesh the solid body with solid elements. This results in the nodes on the bottom face of the ribs being connected to both a solid and a shell element.

When you turn on Thick Shells and Beams, you will notice that the shells on the bottom of the ribs are overlapping with the solid elements. This can be fixed by using an offset on the shell element to put the element thickness below the node instead on either side of the node.  Then the shell thickness will not overlap with the solid elements.  You should reduce the height of the rib by the thickness of the shell to keep the total thickness of the model with the offest shells correct.

You should also add a mesh control on the solid body to get two elements through the thickness of the rib as one element through the thickness of solid elements is less accurate for bending problems.