Prescribed Displacement

The 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.


	If a zero displacement is applied in all directions, this is the same as a Fixed Constraint.


	For details, see Prescribed Displacements, Velocities, and Accelerations.

Prescribed Displacement

Define the prescribed displacements using a (the default) or a .

Standard Notation

To define the displacements individually, click the button.

Select one or all of the ,, and for 3D components, 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 and check boxes. Then enter a value or expression for u0 and w0.

General Notation

Click the 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 Hmatrix H select , , , or and then enter values as needed in the field or matrix. Enter values or expressions for the Rvector R.

For example, to achieve the condition u = v, use the settings

which force the domain to move only diagonally in the xy-plane.

Constraint Settings

To display this section, click the button (

) and select . Location in User Interface

In the COMSOL Multiphysics Reference Manual:

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Constraint Reaction Terms

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Weak Constraints

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Constraint Settings


	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.

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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.

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You can activate and deactivate this boundary condition by assigning it to a constraint group. See Load Cases in the Structural Mechanics Modeling chapter.

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You can assign the value of the prescribed displacement to a load group. See Load Cases in the Structural Mechanics Modeling chapter.

Context Menus

(Boundary)
(Edge)
(Point)
(Boundary)

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