To Create a Rigid Link (FEM Mode)
You can create a rigid link that connects points, vertices, edges or curves, or surfaces so they will move together as if part of a single rigid body.
1. Click > 
Rigid Link. The Rigid Link Definition dialog box opens.
Rigid Link. The Rigid Link Definition dialog box opens.2. Specify a name for the rigid link, or accept the default name. Click the color swatch adjacent to Name if you want to change the color of the icon, the distribution, and the text displayed for the rigid link.
3. Select one of the following types of rigid links:
◦ Simple—Create a rigid link between references that can be a collection of any number of any type of geometric entities. If you select Simple as the type of rigid link, then proceed directly to step 9 to create the rigid link.
◦ Advanced—Select the geometric entity from the independent and the dependent side for the creation of the rigid links.
4. Select one of the following reference types for the independent side. You can select any of the following geometric references:
◦ Point—Select a point or a vertex. If you select Point as the reference type, then the options available for selection on the Dependent Side are Points, Edges/Curves and Surfaces where you can select several points or vertices, several edges or curves, or several surfaces.
◦ Surface—Select a surface. If you select Surface as the reference type on the independent side, then the only option available for selection for the Dependent Side is Surface.
5. Select one of the following coordinate systems for the Independent Side:
◦ World—WCS is the default coordinate system.
◦ Selected CS—select a UCS.
◦ Nodal CS—uses the nodal coordinate system of the elements for the orientation. The selected nodes are oriented for nodal displacement.
6. ClickProject to References to create a rigid link between the selected point on the independent side and the projection of that point on the dependent side. This option is available only when you select a point on the independent side and edges or curves, or surfaces on the dependent side.
7. As on the independent side, select a coordinate system in the CSYS area for the dependent side.
8. Accept the default or select a combination of DOF for the dependent side.