Defining coupling constraints

You use a coupling constraint to constrain the motion of a surface to the motion of one or more points. You can create a coupling constraint by specifying one or more control points, a constraint region, and an influence radius that defines the points in the constraint region to include in the constraint. You can specify a kinematic or distributing coupling constraint type. For detailed information about coupling constraints, see Coupling constraints.

Related Topics
Understanding constraints
In Other Guides
Coupling constraints

  1. From the main menu bar, select ConstraintCreate.

    Tip: You can also create a coupling constraint using the tool in the Interaction module toolbox.

  2. In the Create Constraint dialog box that appears, do the following:

    1. Name the constraint. For more information about naming objects, see Using basic dialog box components.
    2. From the Type list, select Coupling, and then click Continue.

  3. Select one or more points to define the constraint control points using one of the following methods:

    • Select one or more points in the viewport.

      Tip: The Select the Entity Closest to the Screen tool in the Selection toolbar is toggled off by default. If you make an ambiguous selection, Abaqus/CAE highlights the point and displays a description of the point in the lower left corner of the viewport. Use the Next and Previous buttons to cycle through the possible selections, and click OK to confirm your selection.
      (For more information, see Selecting objects within the current viewport.) Click mouse button 2 to indicate that you have finished selecting.

      If the model contains a combination of mesh and geometry, click one of the following from the prompt area:

      • Click Geometry if you want to select the constraint control point from geometry or select a reference point.

      • Click Mesh if you want to select the constraint control point from a native or orphan mesh selection.

    • Use an existing set to define the region. On the right side of the prompt area, click Sets. Select an existing set from the Region Selection dialog box that appears, and click Continue.

      Note:

      The default selection method is based on the selection method you most recently employed. To revert to the other method, click Select in Viewport or Sets on the right side of the prompt area.

    The points that you select become highlighted in red in the viewport.

  4. In the prompt area, select one of the following to define the constraint region type:

    • Select Surface if you want to select a surface.

    • Select Node Region if you want to select a region from which to create a node-based surface.

  5. Select the constraint region using one of the following methods:

    • Select a region in the viewport. (For more information, see Selecting objects within the current viewport.) Click mouse button 2 to indicate that you have finished selecting.

      If the model contains a combination of mesh and geometry, click one of the following from the prompt area:

      • Click Geometry if you want to select the surface from a geometry region.

      • Click Mesh if you want to select the surface from a native or orphan mesh selection.

    • Use an existing surface to define the region. On the right side of the prompt area, click Surfaces. Select an existing surface from the Region Selection dialog box that appears, and click Continue.

      Note:

      The default selection method is based on the selection method you most recently employed. To revert to the other method, click Select in Viewport or Surfaces on the right side of the prompt area.

    The region that you select becomes highlighted magenta in the viewport, and the constraint editor appears.

  6. From the editor, choose one of the following Coupling type categories:

    • Choose Kinematic to define a kinematic coupling constraint between the control points and the points in the constraint region, and toggle on the degrees of freedom that you want to constrain.

    • Choose Continuum distributing or Structural distributing to define a distributing coupling constraint between the control points and the points in the constraint region. Abaqus/CAE automatically constrains the translational degrees of freedom.

      1. Toggle on the rotational degrees of freedom that you want to constrain.

      2. Click the arrow next to the Weighting method field, and select a weighting method from the list that appears. For more information, see Coupling constraints.

  7. From the editor, choose one of the following methods to define the Influence radius:

    • To outermost point on the region. Abaqus includes all points (nodes) on the specified region in the coupling definition.

    • Specify. You can specify the radius of a sphere, centered about the constraint control points, to limit the points in the coupling definition. For more information on selecting the coupling points, see Coupling constraints.

  8. If desired, toggle on Adjust control points to lie on surface. Abaqus/CAE will move the control points to lie on the constraint surface.

  9. If you want to change the coordinate system (CSYS) for the coupling constraint, click and use one of the following methods:

    • Select a predefined datum coordinate system by name.

      1. From the prompt area, click Datum CSYS List to display a list of datum coordinate systems.

      2. Select a name from the list, and click OK.

    • Select a predefined coordinate system in the viewport.

      Tip: The tool in the Selection toolbar is toggled off by default. For coordinate systems with coincident origins, when you cycle through all of the possible selections, Abaqus/CAE highlights the coordinate system and displays the description of the coordinate system in the viewport.

    • Click Use Global CSYS from the prompt area to use the global coordinate system.

  10. Click OK to save your constraint definition and to close the editor.