Fixed Constraint
The Fixed Constraint node adds a condition that makes the geometric entity fixed (fully constrained); that is, the displacements and rotations are zero in all directions.
Face Defining the Local Orientations
This setting is used in conjunction with weak constraints. In order to be able to interpret the orientations of rotations to which the Lagrange multipliers are defined, you must know to which boundary they are applied. Select the boundary which should be used when setting up the weak constraints. The default is Use face with lowest number.
This section is available only for edges and points in the Shell interface and is only visible if Advanced Physics Options has been selected.
Constraint Settings
To display this section, click the Show button () and select Advanced Physics Options.
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
You can activate and deactivate this boundary condition by assigning it to a constraint group. See Load Cases in the Structural Mechanics Modeling chapter.
Location in User Interface
Context Menus
 Shell>Face Constraints>Fixed Constraint
Shell>More Constraints>Fixed Constraint (Edge)
Shell>Points>Fixed Constraint
Plate>Face Constraints>Fixed Constraint
Plate>More Constraints>Fixed Constraint (Boundary)
Plate>Points>Fixed Constraint
Ribbon
Physics tab with Shell selected:
Boundaries>Face Constraints>Fixed Constraint
Edges>More Constraints>Fixed Constraint
Points>Shell>Fixed Constraint
Physics tab with Plate selected:
Boundaries>Face Constraints>Fixed Constraint
Edges>More Constraints>Fixed Constraint
Points>Plate>Fixed Constraint