Performing Sheet Body Operations

Keep in mind the data entry and graphic cursor construction techniques described in the Geometry Overview. The same rules for performing sheet body operations, including booleans, imprints, trims, etc., will also apply. The mouse cursor is used for locating control points in the Model View, and the input fields in the Geometry tab of the Input dialog override the cursor location.

The following describes the use of sheet body operations for constructing complex sheet (surface) bodies in StressCheck.

Target & Tool Bodies

For example, a boolean operation requires as input two or more sheet bodies, one of which is designated as the target body (highlighting green with selection), and the remaining bodies are designated as tool bodies (highlighting red with selection). The target body is generally the object which survives after the boolean operation is performed. When performing a boolean operation, you are designating existing sheet bodies as input to a boolean operator, and the result is one or more sheet bodies. The definitions of each target body, tool body and boolean operator are preserved in StressCheck’s data structure.

The result body (or bodies) may then be used as input to a subsequent boolean, imprint, trim, Body-Solid or other operation. Although a tool body may be suppressed from the Model View, its definition remains in the StressCheck data structure, and its dimensions may be modified either through an edit operation or through a parametric change.

For an example of sheet body operations, refer to StressCheck Tutorial: Extraction a 2D Surface Profile from a 3D Solid.

Preparing for Sheet Body Operations

Before creating a new sheet body, you must select Class > Geometry or the Geometry tab in the Input dialog. As described in the Geometry Overview, sheet body operations also rely heavily on the Class > Action > Object > Method (C/A/O/M) command paradigm. In sheet body operations the most important Action is of course Create. To access geometric construction of sheet body objects, first enable Surface in the Surface/Curve Selector:

Note: by default solids are a dark blue color (Figure 1b), whereas surfaces are a bright blue color (Figure 1c).

Once a sheet body object/operation has been selected a method must be chosen. While not all methods may be appropriate for every sheet body object/operation, each method works in a consistent way for every corresponding sheet body object/operation. Brief descriptions of each sheet body creation method are included below. Note: Body-Copy and Body-Sheet operations will be only available for the 3D reference. All other sheet body operations are available for the Planar and 3D references.

Boolean (Body) Operations

To access the boolean operations for sheet bodies, change the C/A/O/M to Create > Body, then select one of the below methods.

Bool-Union Method

The Bool-Union (boolean union) method is used to create a new sheet body by performing a union between two or more intersecting sheet bodies. There can only be one target (several tool objects are possible) object for a boolean union operation. Simply select the target body (which will highlight green), then the tool body (or bodies, which will highlight red), and click Accept.

Figure 2a shows three sheet bodies before a boolean union operation, and Figure 2b shows the result.

Bool-Union-Gen Method

The Bool-Union-Gen (boolean union general) method is used to create a new sheet body by performing a union between two or more intersecting sheet bodies. There can only be one target (several tool objects are possible) object for a boolean union general operation. Note: both Bool-Union and Bool-Union-Gen methods use the same Parasolid function. The difference is that the Bool-Union-Gen method will retain all intersecting curves between unioned sheet bodies. Simply select the target body (which will highlight green), then the tool body (or bodies, which will highlight red), and click Accept.

Figure 3a shows three sheet bodies before a boolean union general operation, and Figure 3b shows the result.

Bool-Subtract Method

The Bool-Subtract (boolean subtraction) method is used to create a new sheet body by performing a subtraction between two or more intersecting sheet bodies. There can only be one target (several tool objects are possible) object for a boolean subtraction operation. Simply select the target body (which will highlight green), then the tool body (or bodies, which will highlight red), and click Accept. Note: the target body is the sheet body expected to result after the boolean subtraction operation.

Figure 4a shows three sheet bodies before a boolean subtraction operation, and Figure 4b shows the result. In this case, the left-hand sheet body was the target body.

Bool-Intersect Method

The Bool-Intersect (boolean intersection) method is used to create a new sheet body by computing the shared region(s) between two or more intersecting sheet bodies. There can only be one target (several tool objects are possible) object for a boolean intersection operation. Simply select the target body (which will highlight green), then the tool body (or bodies, which will highlight red), and click Accept.

Figure 5a shows three sheet bodies before a boolean intersection operation, and Figure 5b shows the result.

Body-Imprint Operations

Body-Imprint operations work by “splitting” a selected sheet body into new trimmed surfaces by imprinting one or more selected curves. To access the imprint operations for sheet bodies, change the C/A/O/M to Create > Body-Imprint then select one of the below methods.

Curve Normal Method

Select a target sheet body (green highlight) and one or more curves (red highlight), then click Accept. This will imprint the selected curve(s) on the selected sheet body by projecting them locally down face normal.

Figure 6a shows a sheet body and curves to be imprinted, and 6b shows the result.

Note: in some cases it may be necessary to update the imprint tolerance (Tol:) to ensure the result is as expected.

Curve Vector Method

Select a target sheet body (green highlight) and one or more curves (red highlight), optionally hold Ctrl + Shift and select a local system, then click Accept. This will imprint the selected curve(s) on the selected sheet body by projecting them in the specified system’s Z axis direction.

• If no local system is supplied, the direction of projection corresponds to the direction of the positive global Z axis.
• If a local system is selected , the direction of projection corresponds to the direction of the positive local Z axis.

Selection of a local system Z-axis is most applicable working with sheet or solid bodies in 3D space. When working with sheet bodies in 2D (Planar) space, the Curve Normal method and Curve Vector method with no local system selected will be identical.

Note: in some cases it may be necessary to update the imprint tolerance (Tol:) to ensure the result is as expected.

Body-Trim Operations

Body-Trim operations work by removing a selected trimmed surface (or surfaces) from a sheet body. To access the trim operations for sheet bodies, change the C/A/O/M to Create > Body-Trim > No Heal. Next, select one or more surfaces within the sheet body (red highlight). Then, click Accept to trim the surfaces from the sheet body.

Figure 7a shows the surfaces to be trimmed from a sheet body, and Figure 7b shows the result.

Body-Copy Operations

Body-Copy operations are a way to copy an existing body and to orient the copy anywhere in space. To perform the copy, select the body and a reference system. The reference system is needed in order to identify a reference location in the body and the orientation of the parent body. You may supply the location and orientation of the copy using the input fields. Alternatively, if you hold Ctrl-Shift and select an existing system (other than the previously selected reference system) the copy will be attached to the second system.

To access the copy operations for sheet bodies, set the reference to 3D, change the C/A/O/M to Create > Body-Copy then select one of the below methods.

Child Method

The Child method will construct a copy of the selected body and retain a connection to the original so that if the parent body is parametric and dimensions are changed, the child will automatically be updated, and thus remain a consistent copy of the parent.

Orphan Method

The Orphan method will break the connection to the parent body so that if the parent dimensions are changed, the copy will not inherit the change.

Body-Sheet Operations

Body-Sheet operations allow wireframe bodies or curves to be converted to sheet bodies. To access Body-Sheet operations, set the reference to 3D, change the C/A/O/M to Create > Body-Sheet then select one of the below methods.

Sweep Method

Construct a sheet (surface) body by sweeping a profile curve along a path curve. First select the profile curve, then the path curve. The sheet body will be automatically created.

Figure 8a shows the profile curve and the path curve, and Figure 8b shows the resulting swept sheet body.

Spin Method

Select a curve to be spun about the Z-axis of a local system to form a surface. The local system must be selected while holding the Ctrl + Shift keys. If no local system is supplied, the spin will be performed about the global Z axis. Supply the Angle: (in degrees) that the curve will be spun from the positive X-axis. Then click Accept to create the sheet body.

Figure 9a shows the profile curve and the local system, and Figure 9b shows the resulting spun sheet body for Angle: 45.

Extrude Method

Select a curve that will be extruded to form a sheet body surface, and supply the distance to the first edge (Dist1) of the new surface and the distance to the second edge (Dist2). Select a local coordinate system (while holding the Ctrl + Shift keys) to determine the direction of the extrusion (along positive Z-axis). If no system is selected, the extrusion will be relative to the positive global Z-axis.

Fill Hole Method

Fill a hole in a surface by selecting one or more edges which bound the hole to be filled. After the operation, the face(s) formed by filling the hole will become part of the body that contained the selected edge(s). The body that results from a fill operation will not be a solid. To convert a body to a solid, you must use the Create/Body-Copy operation.