To create a free body cut, select the nodes and elements that comprise your free body cross-section; that is, select the surface of your model across which you want to investigate the resultant force and moment. Abaqus/CAE provides several methods for selecting the nodes and elements for a free body cross-section:
For three-dimensional objects, you can select individual element faces to include in the free body cross-section. Each face (or “facet”) that you select in this manner provides Abaqus/CAE with an element definition, an element face, and multiple nodes.
For two- or three-dimensional objects, you can select individual element edges to include in the free body cross-section. Each edge provides Abaqus/CAE with an element definition and two or three nodes to include in the free body cross-section.
For any type of model, you can select the nodes and elements you want to include individually. This method is recommended for selecting nodes and elements from geometrical areas, such as the ends of beams, in which it might be awkward or difficult to select nodes and elements using their edges or faces.
When you define a free body cross-section using element faces or element edges, Abaqus/CAE provides three additional selection methods that enable you to select the nodes and elements for this definition:
You can select the faces or edges by picking components in the viewport, either individually or by angle.
You can select a surface set, which is defined in the output database.
You can select one or more display groups to use as part of your surface definition.
Note: If you define a free body cross-section using element faces, Abaqus/CAE does not include NFORC data from elements whose faces are not on the specified surface. This situation occurs readily with tetrahedral meshes. If you want to ensure that all desired elements with nodes on the specified surface participate in the free body summation, you can select these nodes and elements individually in the free body cut definition or you can investigate free body forces on an arbitrary plane by using a view cut. For more information about the latter method, see “Understanding view cuts,” Section 46.1.
When you define a free body cross-section by selecting nodes and elements individually, you can specify the nodes or elements you want to include in the definition by typing their labels directly into the Free Body Cross-Section dialog box.
Abaqus/CAE also enables you to customize the summation point for a free body cut, which is the three-dimensional location about which resultant moments are taken. By default, the summation point will be placed at the centroid location of the nodes for the free body cross-section, but you can move the summation point to any three-dimensional location in your model.
You can also adjust the orientation of component vector display for a free body cut. In many cases the most desirable coordinate system for a free body cut is one in which one axis is normal to the surface of the model and another axis is tangential to the surface. This “normal and tangential” coordinate system is created internally and used by default for the display of component vectors. However, you can change the orientation to use any custom coordinate system available in your session.
You cannot save free body cuts to the output database file. If you want to retain a free body cut that you have defined, record the process of defining that free body cut as a macro in Abaqus/CAE. For more information on macros, see “Managing macros,” Section 9.10.
To create a free body cut:
From the main menu bar in the Visualization module, select Tools
Free Body CutCreate.
Tip:
You can also create a free body cut by using the 
tool in the Visualization module toolbox.
The Create Free Body Cut dialog box appears.
From the Selection Method options, choose one of the following options:
Select Based on view cut to calculate and display a free body cut based on the current view cut. If you choose this selection method, Abaqus/CAE opens the View Cut Manager, from which you can display and position a view cut for your model and customize the display of an associated free body cut. For more information, see “Customizing free body display on the active view cut,” Section 46.2.6.
Select 2D element edges to specify the nodes and elements implicitly (or indirectly) by selecting element edges. This method is recommended for two-dimensional models.
Select 3D element faces to specify the nodes and elements implicitly (or indirectly) by selecting element faces. This method is recommended for three-dimensional models.
Select Elements and nodes to select the elements or nodes individually for your free body cross-section.
Click Continue.
The Free Body Cross-Section dialog box opens, from which you can select the edges, faces, or elements and nodes that constitute the free body cross-section.
From the Item list at the top left of the dialog box, select Surfaces, Display groups, Elements, or Nodes as the type of model component to use for the free body cross-section.
Abaqus/CAE refreshes the Method list.
Choose a selection method from the Method list; and/or select the specific items for the free body cross-section by picking from the viewport, selecting items from the list that appears on the right side of the dialog box, or entering data in the right side of the dialog box.
For more information about selection options, see “Selection methods for free body cross-sections,” Section 64.3.
Certain items can be highlighted in the viewport to verify your selection. Toggle Highlight items in viewport if available.
When you have completed your selections, click OK to close the Free Body Cross-Section dialog box.
The Edit Free Body Cut dialog box opens.
If desired, customize the summation point or the coordinate system transformation options for the selected free body cut.
From the Summation point options, select the three-dimensional location from which the vectors in the free body cut originate.
Select Centroid of cut to place the summation point automatically at the averaged deformed coordinates of all nodes included in the free body cut.
Specify a custom three-dimensional location in space in the User-defined field.
From the Component resolution options, you can specify the coordinate system transformation that takes place when vectors are displayed in component form. (See “Customizing general display options for free body cuts,” Section 64.5.1, for more information about displaying force and moment vectors in component form.)
Select Normal and tangential to orient the component vectors with the normal and the tangent of the surface you select.
Select CSYS and a coordinate system to transform the component vectors to a custom coordinate system.
The Component resolution options affect display of free body cuts only when component vector display is selected in the Free Body Plot Options dialog box.
Click OK.
Abaqus/CAE creates the free body cut and displays it in the viewport.
