Prescribed Displacement
The Prescribed Displacement node adds a condition where the displacements are prescribed in one or more directions to the geometric entity (domain, boundary, edge, or point).
If a displacement is prescribed in one direction, this leaves the solid free to deform in the other directions.
You can also define more general displacements as a linear combination of the displacements in each direction.
Shell Properties

Interface Selection

Prescribed Displacement
Define the prescribed displacements using a Standard notation or a General notation.
Standard Notation
To define the displacements individually, click the Standard notation button.
Select one or all of the Prescribed in x direction, Prescribed in y direction, and for 3D components, Prescribed in z direction check boxes. Then enter a value or expression for u0, v0, and for 3D components, w0. For 2D axisymmetric components, select one or both of the Prescribed in r direction and Prescribed in z direction check boxes. Then enter a value or expression for u0 and w0.
General Notation
Click the General notation to specify the displacements using a general notation that includes any linear combination of displacement components. For example, for 2D components, use the relationship
For H matrix H select Isotropic, Diagonal, Symmetric, or Full and then enter values as needed in the field or matrix. Enter values or expressions for the R vector R.
For example, to achieve the condition v, use the settings
which force the domain to move only diagonally in the xy-plane.
Constraint Settings
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box.
In the COMSOL Multiphysics Reference Manual:
When Individual dependent variables is selected in the Apply reaction terms on drop-down list, the constraint forces are applied directly on the degrees of freedom, which are the displacements along the global coordinate axes. If you use this setting together with a local coordinate system, the results will be inconsistent since the constraint forces will not match the constraint orientation.
You can add a Harmonic Perturbation subnode for specifying a harmonic variation of the values of the prescribed displacements in a frequency domain analysis of perturbation type.
Location in User Interface
Context Menus
Ribbon
Physics tab with Solid Mechanics selected:
Physics tab with Membrane selected:
Physics tab with Truss selected:
Physics tab with Multibody Dynamics selected: