Element and Edge Sets

Named selections defined in Mechanical or components defined Mechanical APDL can be imported into ACP. These selections are imported with the same names. Faces (element components in Mechan-ical APDL) are imported as Element Sets (p. 68) and edges (node components in MechanMechan-ical APDL) as Edge Sets (p. 69).

Important

After the definition of a new Named Selection in Mechanical, the model must be updated.

Features

2.1.3.1. Element Sets

New Element Sets can be manually defined by selecting individual elements. Element Sets store the element labels and are therefore not associated with the geometry. If the mesh changes, the element numbering changes and the element set must be redefined to avoid erroneous layups.

Figure 2.25: Element Set Selection

• Middle Offset: If the mesh is generated at the mid-plane surface, activate this option so that the section definition is translated to where the middle of the section corresponds to the element.

• Operation: Add or Remove elements in the list.

• Mode: Define the selection mode by dragging the mouse from one corner to the other.

– Box on Surface: Only visible elements are selected.

– Box Prism: All elements included in the box are selected, depth included.

– Point: Element at the picking location is selected.

2.1.3.1.1. Context Menu

Several options are available in the element set context menu:

• Properties: Open the element set property window.

• Update: Update any changes into the database

• Hide/Show: Hide or show this Element Set. The elements of the hidden Element Sets are no longer visible in the scene.

• Copy: Copy the selected Element Set to the clipboard.

• Paste: Paste an Element Set from the clipboard.

• Delete: Delete the selected Element Set

• Export Boundaries: Export the boundaries of the Element Set to a STEP or an IGES file

• Partition: Create partitioned Element Sets for any Element Set that can be divided in different zones, due to a geometrical separation (for example, three elements share the same edge).

Figure 2.26: Element Set Context Menu

2.1.3.2. Edge Sets

New Edge Sets can be manually defined by selecting nodes:

Figure 2.27: Edge Set Definition

• Edge Set Type: How the Edge Set is defined:

– Imported: Imported with the model.

– By Reference: Defined the Edge Set using an existing Element Set (activates the following options):

→ Element Set: The Element Set of which the Edge Set is part.

→ Limit Angle: The Edge Set is extended from the origin in both directions until the angle between two Features

→ Origin: Origin to determine the closest boundary.

• By Reference: An existing Element Set is used to define a new Edge Set through one boundary limited by an angle diffusion.

• By Nodes: Manually select the nodes to define the Edge Set.

2.1.4. Geometry

Geometries can be used to build complex lay-ups during preprocessing in ACP. For example, core of variable thickness can be modeled as a ply whose thickness is set by an imported geometry of the core.

Cut-off Rules can be based on geometry, thus controlling the lay-up by a CAD surface or at a pre-defined offset to a CAD surface. The use of geometries is particularly helpful in the generation of solid models where geometry-based extrusion guides, snap-to and cut-off operations can create intricate shapes.

For more information on the use of geometries in a lay-up definition, see the following sections:

• Ply thickness definition (p. 103) in Modeling Groups

• Geometry-based Cut-off Selection Rule (p. 86)

• Extrusion Guides (p. 132),Snap-to (p. 137) and Cut-off Geometries (p. 140) in Solid Models (p. 122) CAD geometries are incorporated in an ACP model by creating a link to a Geometry in the Workbench Project Schematic or by directly importing an external geometry (IGES or STP format). These CAD geo-metries may be surfaces, bodies, or assemblies of parts. The concept of virtual geogeo-metries allows you to select and group specific regions or bodies of the imported CAD geometry and use them for sub-sequent modeling operations. All geometry-based operations are based on virtual geometries. Virtual geometries act as a reference to one of more faces or bodies of one CAD geometry.

Figure 2.28: CAD Geometry Assembly and Virtual Geometries in the Tree View

2.1.4.1. CAD Geometries

There are two ways to import an external geometry into ACP: directly through ACP or through a geometry link in Workbench. The advantage of the Workbench geometry link is that the CAD geometry remains intact when a project is archived and restored elsewhere.

The parts included in an imported CAD geometry are displayed once the CAD geometry is up-to-date.

If the imported CAD geometry is an assembly of parts, multiple parts are shown in the tree underneath the CAD geometry. ACP makes the distinction between four different types of parts:

• Face ( ): Single face

• Surface ( ): Single surface body

• Solid ( ): Single volume body

• Compound ( ): Combination of multiple connected surfaces and/or bodies

2.1.4.1.1. Direct Import

Geometry import has the following options:

Figure 2.29: Import External CAD Geometry

• Name: Name of geometry for use in the database.

• Path: Location of the geometry file.

• Scale Factor: Scale the geometry in the global coordinate system (useful for change of units).

• Precision: Precision of the imported geometry. This value is used to evaluate intersections and other geo-metrical operations.

• Offset: Sets the default capture tolerance value associated with the CAD geometry for operations such as the CAD Selection Rule (p. 89).

• Use Default Offset: Boolean which sets the offset to 10% of the average element size.

• Visualization Color: Color in which the imported geometry is displayed.

Features

Assemblies should be imported as a single .STP file rather than individual ones containing links.

2.1.4.1.2. Workbench Geometry Link

The geometry component in Workbench can be used to link CAD geometries with ACP-Pre. The linked geometry is scaled automatically if its units do not match those of the project. The required steps for geometry import are: