A prescribed displacement can be applied to nodes, edges, or surfaces of a model.
What Does a Prescribed Displacement Do?
- An edge or surface prescribed displacement applies nodal prescribed displacements to each node on the edge or surface.
- A prescribed displacement causes a node to translate or rotate a specified distance in a specified direction. A new node is actually added to the model. This new node undergoes the specified translation or rotation value entered in the Magnitude field. The direction of this translation or rotation is specified using a vector in the Direction section. The new node is coupled to the model using an elastic boundary element.
- The amount that the node on the model translates or rotates depends on the value in the Stiffness field. The elastic boundary element used to attach the prescribed displacement to the model acts like a spring and follows the equation F=kx. A large stiffness value, k, will cause the node on the model to move the same amount as the new node. A low stiffness value causes the boundary element itself to deflect and therefore absorb some of the prescribed displacement. It causes the displacement of the node on the model to be less than the value entered in the Magnitude field.
- For prescribed displacements to be used in the analysis, you must specify a Multiplier in the Displacement column of the Multipliers tab in the Analysis Parameters dialog box. The value entered is multiplied by the value in the Magnitude field. The product is the displacement applied to the new node of the displacement boundary elements.
- The force or moment required to move the node the specified distance can be found in the Results environment using the Linear Results Menu pull-out menu. You can see the force or moment along the vector that the node was displaced.
Apply Prescribed Displacements
If you have nodes, edges or surfaces selected, you can right-click in the display area and select the Add pull-out menu. Select the Nodal Prescribed Displacements, Edge Prescribed Displacements or Surface Prescribed Displacements command. You can also use the 
Setup 
Constraints Prescribed Displacement ribbon command. Edge prescribed displacements can only be applied to parts that originated from CAD solid models or 2D Mesh Generation.
Determine if you want the prescribed displacement to apply a translation or rotation to the node by selecting the appropriate radio button in the Type section. Specify the magnitude of the displacement in the Magnitude field and the direction of the movement in the Direction section. Specify the stiffness of the boundary element used to couple the prescribed displacement to the model in the Stiffness field.