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

Coordinate System Selection
The constraints are applied in the axis directions of the coordinate system selected in this section. You should only use a coordinate system that has fixed spatial directions.
Prescribed Displacement
Select a NotationStandard or General.
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, Prescribed in z direction check boxes (only applicable check boxes are shown based on the spatial dimension). Then enter a value or expression for the corresponding inputs u0, v0, and w0. For 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. When twist is included in 2D axisymmetry, the circumferential displacement can also be prescribed.
General Notation
In 3D, 2D, or 2D axisymmetry, 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 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 Wire selected:
Physics tab with Multibody Dynamics selected:
Physics tab with Thin Layer node selected in the model tree: