Defining a secondary base motion boundary condition

You can create a secondary base motion boundary condition in a frequency extraction step. If a subsequent modal dynamic or steady-state dynamic (mode-based or subspace-based) step has more than one independent base motion, the driven nodes must be grouped together into secondary bases in addition to the primary base. See Defining primary and secondary bases for modal superposition procedures, for a complete discussion of base motion boundary conditions.

Related Topics
Creating and modifying prescribed conditions
Understanding symbols that represent prescribed conditions

  1. Display the boundary condition editor using one of the following methods:

  2. Select the region to which you want to apply the boundary condition. Double-click in the empty table cell under the Region column and use one of the following methods:

    • Select a region in the viewport. You can use the angle method to select a group of faces or edges from geometry or a group of element faces from a mesh. For more information, see Using the angle and feature edge method to select multiple objects. When you have finished selecting, click mouse button 2.

      Tip: You can limit the types of objects that you can select in the viewport by specifying filtering options in the Selection toolbar. See Using the selection options, for more information.

      If the model contains a combination of mesh and geometry, you must choose the type of region to which you want to apply the boundary condition. From the prompt area, select one of the following:

      • Click Geometry to apply the boundary condition to geometry or to a reference point.

      • Click Mesh to apply the boundary condition to a native or orphan mesh selection.

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

      1. Click Sets on the right side of the prompt area.

        Abaqus/CAE displays the Region Selection dialog box containing a list of available sets.

      2. Select the set of interest, 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.

  3. Select the Constrained-degrees-of-freedom in the table by clicking one or more checkboxes.

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