Applying Restraints

Restraint boundary conditions can be applied to boundaries using the menu/toolbar options, or by convenient right-click shortcut.

To apply restraints using the menu/toolbar options:

1. Select the restraint option you would like to apply (Restrain X , Restrain Y , Restrain XY, Free, or Constant) from the toolbar or the Displacements menu.

Note: Restraints can only be applied after the mesh is generated. If the mesh does not exist then the Restraint options will be disabled.

2. Restraints are applied by selecting boundary line segments, joint segments, vertices or nodes along boundaries. You can choose the required mode from the Selection Mode sub-menu in the Displacements menu, or from the right-click menu. The available options are:
3. • Pick by Segment
   • Pick by Vertex
   • Pick by Boundary Node

The default selection mode is Pick by Segment.

4. Use the mouse to select the desired boundary segments, joint segment, vertices or nodes. When a user selects a joint segment, they will be able to select which side of the joint to be restrained. When you are finished selecting, press Enter or right-click and select Done Selection. The restraint option you have selected in Step 1 will be applied to all selected nodes.

Whenever you apply restraints, all existing restraints (i.e. roller and pin symbols) will be displayed on the model, if they are not already displayed. The display of restraints can be toggled on or off at any time in the Display Options dialog.

Selection Mode (Segment / Vertex / Node)

The Selection Mode options allow the user to choose the most appropriate method for applying the restraint boundary conditions. The mode can be selected from the Selection Mode sub-menu in the Displacements menu, or from the right-click menu after you have selected a Restraint option to apply. The following selection modes are available.

• Pick by Segment – restraints are applied to entire boundary segments (i.e. only boundary segments can be selected, and boundary conditions will be applied to all nodes of the selected segments). This is the default method. When a user selects a joint segment, they will be able to select which side of the joint to be restrained.
• Pick by Vertex– only vertices of boundaries can be selected (i.e. the vertices which define the boundary geometry).
• Pick by Boundary Node – any node(s) along a boundary can be selected.

NOTE: Restraint boundary conditions are actually always applied to nodes of the mesh, regardless of the selection mode (i.e. even when you select Pick by Segment or Pick by Vertex, the boundary conditions are always applied to the mesh nodes along the boundary, and not to the geometric boundary entity).

Right-Click Shortcut for Applying Restraints

Restraints can also be applied using the following right-click shortcut:

1. Right-click the mouse directly on a boundary line segment or vertex.
2. The segment or vertex will be highlighted and a popup menu will appear.
3. Select a Restraint option from the popup menu (Restrain X, Restrain Y, Restrain XY, Free or Constant), and the selected boundary condition will be applied to the selected segment or vertex.

This allows you to quickly change the restraint boundary conditions on any boundary line segment or vertex, without having to use the toolbar or menu options. The finite element mesh must exist in order for this right-click option to be enabled.

Note: you cannot use the right-click method to apply restraints to individual boundary nodes (unless the node is coincident with a boundary vertex). If you need to apply restraints to non-vertex nodes along a boundary, then you must select a Restraint option from the toolbar or menu as described above, and toggle the Selection Mode to Pick by Boundary Node.