20.4.3 Creating springs and dashpots connecting two points

You can define springs and dashpots that connect two points and exhibit the same linear behavior independent of field variables. For more information, see Springs, Section 26.1.1 of the ABAQUS Analysis User's Manual, and Dashpots, Section 26.2.1 of the ABAQUS Analysis User's Manual.

To create springs and dashpots that connect two points:

  1. From the main menu bar in the Property module or the Interaction module, select SpecialSprings/DashpotsCreate.

  2. In the Create Springs/Dashpots dialog box that appears, name the springs/dashpots, select Connect two points, and click Continue.

  3. Select the first point for the first spring/dashpot using one of the following methods:

    • Select the point in the viewport. (For more information, see Chapter 6, Selecting objects within the viewport.”)

      Tip:  The Select the Entity Closest to the Screen tool in the Options toolbox 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.

      If the model contains a combination of orphan mesh instances and native part instances, select one of the following from the prompt area:

      • Select Geometry to define the spring/dashpot for a native part instance or for a reference point.

      • Select Mesh to define the spring/dashpot for an orphan mesh instance.

    • To select from a list of existing sets, do the following:

      1. Click Sets on the right side of the prompt area to display the Region Selection dialog box containing a list of available sets.

      2. Select a set that contains only one point, 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.

  4. Select the second point for the first spring/dashpot using one of the methods described in the previous step.

    The first spring/dashpot point pair and a dashed line connecting them are highlighted in the viewport.

  5. Continue selecting pairs of points for additional springs/dashpots as described in the previous steps. When you have finished selecting point pairs, click Done in the prompt area.

    The Edit Springs/Dashpots dialog box appears. The point pairs that you selected to define each spring/dashpot are listed in the Spring/Dashpot Point Pairs table.

  6. From the Spring/Dashpot Point Pairs table, you can do the following:

    • To define additional springs/dashpots with the same behavior, click Add Pairs and repeat the point selection procedures described in the previous steps to define the first and second points of each spring/dashpot.

    • To edit a point in the table, select the point in the table, double-click on it or click Edit Point, and reselect a point. The selection highlighting in the viewport is updated to show the newly edited point.

    • To identify a specific spring/dashpot in the viewport, select the desired row number. The highlighted dashed line connecting the selected point pairs appears bolder in the viewport.

    • To remove springs/dashpots from the table, select the desired row numbers and click Delete Pairs.

    • To remove all springs/dashpots from the table, click Delete All.

  7. Click the arrow next to the Axis field, and select an option from the list that appears:

    • Select Follow line of action to have the axis of each spring/dashpot follow the line of action of the two points.

    • Select Specify fixed direction to specify the degree of freedom at each point on the spring/dashpot (ABAQUS/Standard analyses only).

  8. If you selected Specify fixed direction, do the following in the Direction portion of the dialog box:

    • Click the arrow next to the Point 1 degree of freedom field, and select the degree of freedom with which the springs/dashpots are associated at their first point.

    • Click the arrow next to the Point 2 degree of freedom field, and select the degree of freedom with which the springs/dashpots are associated at their second point.

    • The global coordinate system determines the default spring/dashpot orientations. To specify an orientation for the springs/dashpots, click Edit. Specify the orientation for the springs/dashpots using one of the following methods:

      • Click Datum CSYS List from the prompt area to select a name from a list of datum coordinate systems.

      • Select a datum coordinate system in the viewport.

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

      ABAQUS/CAE displays the local coordinate system specified for springs/dashpots in the viewport.

  9. In the Property portion of the dialog box, check the appropriate box to include:

    • Spring stiffness. Enter the force per relative displacement for springs.

    • Dashpot coefficient. Enter the force per relative velocity for dashpots.

    If you define both spring and dashpot behaviors, they act in parallel.

  10. Click OK to create the springs/dashpots and to close the Edit Springs/Dashpots dialog box.

    Symbols appear in the viewport that represent the springs/dashpots that you just created.


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