To begin creating a midsurface model, you select the solid model regions that you would like to represent as shells. When you assign a midsurface region to one or more cells of a solid model, Abaqus/CAE creates an Assign Midsurface feature and moves the selected cells from the active representation of the part to the reference representation. The reference representation works similarly to reference geometry in a sketch—using the Geometry Edit toolset, you can select points and edges from the reference representation to create points, edges, and faces in the midsurface model. The new midsurface geometry that you create becomes part of the active representation that will be meshed and analyzed.
Creating the reference representation:
From the main menu bar, select Tools
MidsurfaceAssign.
Tip:
You can also assign midsurface regions using the 
tool, located with the midsurface tools in the Part module toolbox.
Select the solid cells from which you want to create the midsurface model.
You can select individual cells from the viewport or select an existing set of solid cells. For more information on using the selection methods in Abaqus/CAE, see Chapter 6, “Selecting objects within the viewport.”
Abaqus/CAE creates an Assign midsurface feature containing the selected cells and displays them as translucent in the viewport.
Repeat Step 2 to assign more midsurface regions, or click Done to end the procedure.
