Offsets for Shells

You can control the position of the shell mesh to the top, middle, or bottom faces of the shell. To position the mesh to a reference surface, you can type an offset value. By default, the mesh is always aligned to the middle face of the shell.

The Shell Definition PropertyManager has the following options:

Middle surface

Positions the mesh on the middle surface of the shell

Top surface

Positions the mesh on the top surface of the shell

Bottom surface

Positions the mesh on the bottom surface of the shell

Specify ratio

Positions the mesh on a reference surface defined by an offset value that is a fraction of the total shell thickness. The image shows the meaning of the positive and negative offset values.

For example, to model adjacent shells with differing thicknesses such that their bottom faces are aligned, you can create two shell definitions and apply the Bottom surface option for offset.

Offset for shells is not available for large displacement analysis.

After creating the mesh, observe the orientation of the top and bottom shell faces and display the shell thickness for better visualization. Shell bottom faces have orange color. You may need to flip the shell elements to align the shells with the desired orientation.

Apply all loads and boundary conditions at the selected surfaces where the shell mesh is created. You cannot offset load definitions.