Use a Union () operation to create the union of selected geometry objects, as shown in Figure 7-98.

To add a Union operation, in the Geometry toolbar, from the Boolean and Partitions () menu, select Union (). You can also right-click the Geometry node to add this node from the Boolean and Partitions submenu. Then enter the properties of the union operation.

From the Input objects list, choose Manual (default) to select the geometry objects that you want to unite in the Graphics window. Click the Activate Selection button to toggle between turning ON and OFF the Input objects selections. Alternatively, choose All objects to select all objects or choose All nonconstruction objects to automatically select all objects that have not been marked as Construction Geometry. If the geometry sequence includes user-defined selections above the Union node, you can choose one of the selections from the Input objects list.

Select the Keep input objects checkbox to use the selected geometry objects for further geometry operations.

Create a geometry object without interior boundaries by clearing the Keep interior boundaries checkbox, as shown in Figure 7-99. This can be useful to simplify a geometry where the interior boundaries do not separate domains with different physics nodes or materials, for example.

You can change the settings for the Repair tolerance list if you experience problems with the union operation. Geometric entities that have a distance less than the repair tolerance are merged.

When you build this feature, the relative and absolute repair tolerances are set to the values that are used (with a precision of two digits), which can be useful when you have set Repair tolerance to Automatic.

Select the Resulting objects selection checkbox to create predefined selections (for all levels — objects, domains, boundaries, edges, and points — that are applicable) in subsequent nodes in the geometry sequence. To also make all or one of the types of resulting entities (domains, boundaries, edges, and points) that the resulting objects consist of available as selections in all applicable selection lists (in physics and materials settings, for example), choose an option from the Show in physics (Show in instances if in a geometry part; Show in 3D in a plane geometry under a work plane in a 3D component) list: All levels, Domain selection, Boundary selection, Edge selection, or Point selection. The default is Domain selection, which is suitable for use with materials and physics defined in domains. For use with a boundary condition, for example, choose Boundary selection. These selections do not appear as separate selection nodes in the model tree. Select Off to not make any selection available outside of the geometry sequence. From the Color list, choose a color for highlighting the resulting objects selection. See Selection Colors.

If you want to make the resulting entities contribute to a cumulative selection, select a cumulative selection from the Contribute to list (the default, None, gives no contribution), or click the New button to create a new cumulative selection (see Cumulative Selections).

If you have Named Selections that include entities on the input objects, select the Propagate selections to resulting objects (selected by default) checkbox to update the selections to corresponding entities on the output objects, when possible. Clear the checkbox to not propagate the selection to the resulting objects. This can be useful in combination with selecting the Keep input objects checkbox so that the selections refer only to the input objects.

From the Construction geometry list choose On to make the resulting objects available only in the feature’s geometry sequence. The default option Inherit means that the resulting objects become construction geometry if all input objects are construction geometry. Choose Off to never output construction geometry objects. For more information, see Construction Geometry.