Defining a moment

You can create a moment load to define rotation at a vertex or node.

Related Topics
Creating and modifying prescribed conditions
Understanding symbols that represent prescribed conditions
Using analytical expression fields
Creating expression fields
In Other Guides
Concentrated loads

  1. Display the moment load editor using one of the following methods:

  2. Click the arrow to the right of the Distribution field, and select the option of your choice from the list that appears:

    • Select Uniform to define a load that is uniform over the region.

    • Select an analytical field to define a spatially varying load. Only analytical fields that are valid for this load type are displayed in the selection list. Alternatively, you can click to create a new analytical field. (See The Analytical Field toolset,” for more information.)

  3. In the CM1, CM2, and CM3 text fields, enter the components of the moment about each axis (units FL).

    If you leave a text field blank, a moment of zero is assigned to that direction automatically. However, you must enter at least one nonzero component in the editor to define the load.

  4. If desired, click the arrow to the right of the Amplitude field, and select the amplitude of your choice from the list that appears. Alternatively, you can click to create a new amplitude. (See The Amplitude toolset,” for more information.)

  5. If desired, toggle on Follow nodal rotation to make the direction of the load rotate with the rotation at this node.

    Follow nodal rotation affects only nodes that have rotational degrees of freedom and steps in which the Nlgeom setting is turned on.

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

    • Select an existing datum coordinate system in the viewport.

    • Select an existing 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.

      Note:

      You should not apply a moment load at the origin of a cylindrical coordinate system; doing so would make the radial and tangential loads indeterminate.

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

    This coordinate system editing option is available only in the step in which the moment is created. By default, the global coordinate system is used to define the moment.

  7. Click OK to save your data and to exit the editor.