Defining cyclic symmetry

From the main menu bar, select InteractionCreate.

Tip: You can also create a cyclic symmetry interaction using the tool in the Interaction module toolbox.

In the Create Interaction dialog box that appears, do the following:

• Name the interaction. For more information about naming objects, see Using basic dialog box components.

• Select the initial step.

• Select the Cyclic symmetry type of interaction.

Click Continue to close the Create Interaction dialog box.

Select the master surface.

1. In the prompt area, select one of the following:

   • 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.

2. Use one of the following methods to select the master surface:

   • 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.

   • Use the mouse to 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.

     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.

   The master surface that you select becomes highlighted in red in the viewport.

Select the slave surface.

1. In the prompt area, select one of the following:

   • 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.

2. Use one of the same methods described in the previous step to select the slave surface or region.

   The slave surface or region that you select becomes highlighted in magenta in the viewport.

   Abaqus/CAE prompts you to define the axis of symmetry.

Use one of the following methods to select the first point on the axis of symmetry:

• Use an existing set to define the region. The set must contain a single point or vertex. 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.

• Use the mouse to select a node or vertex in the viewport. (For more information, see Selecting objects within the current viewport.)

  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.

The point that you select becomes highlighted in red in the viewport.

Using one of the methods described in the previous step, select the second point on the axis of symmetry.

The point that you select becomes highlighted in magenta in the viewport, and the Edit Cyclic Symmetry dialog box opens.

From the Position Tolerance options, specify the distance within which Abaqus will tie nodes on the slave surface to the master surface. Choose one of the following options:

• Select Use computed distance to use a distance calculated automatically based on the element formulations and types of surfaces used in the constraints.

• Select Specify distance, and enter a value to set the distance within which slave nodes will be tied to the master surface.

Toggle off Adjust slave surface initial position to prevent Abaqus from moving all tied nodes on the slave surface onto the master surface.

By default, this option is toggled on and all tied nodes are moved in the initial configuration without applying strains to the model.

Specify the Total number of sectors that comprise the full 360° structure.

From the Extracted Nodal Diameters options, specify the range of cyclic symmetry nodal diameters for which the eigenfrequency analysis will be performed. You can define this range in the initial step or in a frequency extraction step only. Specify this range using either of the following options:

• Select All possible nodal diameters to extract every possible cyclic symmetry nodal diameter.

• Select Specified range to extract every cyclic symmetry nodal diameter between a Lowest nodal diameter and Highest nodal diameter that you specify. The highest nodal diameter must be less than or equal to half the number of sectors.

Specify the Excited nodal diameter associated with the loading in the load definition. You can select the excited nodal diameter in the initial step or in a mode-based steady-state dynamics step. Only one cyclic symmetry nodal diameter can be excited.

Click OK.

Abaqus/CAE creates the cyclic symmetry interaction.