You can repair the face normals of shell and solid imported parts, and you can perform these repairs on either manifold parts (parts in which every edge is shared by only one or two faces) or non-manifold parts.
If Abaqus reports that the volume of an imported part is negative, it means that the solid has been turned inside out. The Repair normals tool will flip the normals and turn the solid right side out.
An imported shell part can contain faces that have normals pointing in opposite directions. The Repair normals tool will align all the selected normals on a shell part. If the face normals are already aligned, this tool will flip all the selected normals so that they remain aligned but point in the opposite direction.
Note: Abaqus/CAE does not flip normals that have been assigned to shell faces manually using the Element Normal assignment option in the Property module.
When you perform repairs of non-manifold shell parts, you cannot flip the normals for all of the faces in the part in a single operation; you must select each face individually to flip the direction of its normal. Performing a query using the Shell element normals option from the Query dialog box can help you assess the orientation of the face normals before you repair your shell part.
The Query toolset provides a set of geometry diagnostic tools that calculate the volume of a solid part and display the normals of shells and membranes. For more information, see “Using the Query toolset in the Part module,” Section 11.16.4. The operation to repair face normals is stored as a feature of the part; therefore, you can use the Model Tree to delete or suppress the operation.
To repair normals:
From the main menu bar, select Tools
Geometry Edit.
Abaqus/CAE displays the Geometry Edit dialog box.
Tip:
You can also repair face normals using the 
tool, located with the edit tools in the Part module toolbox. For a diagram of the edit tools in the toolbox, see “Using the Geometry Edit toolset,” Section 69.1.
From the dialog box, select the Face category and the Repair normals method.
Select one of the following options from the prompt area:
Click Entire Part to repair face normals for every incorrectly oriented face in your part.
Click Select Faces to select individual faces in your part.
If you are selecting individual faces in your part, choose the face normals that you want to repair from the viewport, then click Done from the prompt area.
You can use a combination of drag-select, [Shift] + Click, and [Ctrl] + Click to select faces in your part, and you can also use the angle method or the face curvature method to select faces. For more information, see “Selecting objects within the current viewport,” Section 6.2.
Abaqus/CAE repairs the face normals.
