Roller
The Roller node adds a roller constraint as the boundary condition; that is, the displacement is zero in the direction perpendicular (normal) to the boundary, but the boundary is free to move in the tangential direction. A Roller condition is similar to a Symmetry condition, but the latter has some other options. The Roller constraint is not available in 1D and 1D axisymmetry; use a Fixed Constraint instead.
Coordinate System Selection
By selecting a coordinate system, you can simplify the description of axis orientations when using the Plane or Cylinder options in the Roller Constraint section.
Roller Constraint
The default roller constraint acts along a normal to the selected boundaries, which is computed numerically. For a certain mesh node, this direction is kept constant during the analysis, so it cannot represent finite sliding on a curved boundary. You can however, for some important cases, prescribe that the boundary slides on an analytical surface. There are two situations where you may want to do this:
Select a Normal orientationAutomatic, Plane, Cylinder, or Sphere.
For Automatic, the constraint is applied in the direction normal to the boundary, as represented by the mesh. This orientation is not updated during the analysis.
For Plane, select Orientation of normalX-axis, Y-axis, Z-axis, or User defined to describe the constraint direction. When User defined is used, enter the vector en, pointing along the normal to the plane along which the boundary is sliding. The orientation is interpreted in the coordinate system given in the Coordinate System Selection section.
For Cylinder, select Axis typeX-axis, Y-axis, Z-axis, or User defined to describe the orientation of the cylinder. When User defined is used, enter the vector es, pointing along the axis of the cylinder. The orientation is interpreted in the coordinate system given in the Coordinate System Selection section. Enter the location of a Point on axis, Xc, in order fix the location of the cylinder. The constraints will act radially from the cylinder axis. If the analysis is geometrically nonlinear, each mesh node is assumed to maintain its distance from the cylinder axis.
For Sphere, enter the location of the Center of sphere, Xc. The constraints will act radially from this point. If the analysis is geometrically nonlinear, each mesh node is assumed to maintain its distance from the center of the sphere.
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 theory section of the Structural Mechanics User’s Guide:
In the COMSOL Multiphysics Reference Manual:
Excluded Edges, Excluded Points
To display these sections (Excluded Edges in 3D geometries only), click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box. For more information about these sections, see Excluded Surfaces, Excluded Edges, and Excluded Points in the COMSOL Multiphysics Reference Manual.
Location in User Interface
Context Menus
Ribbon
Physics tab with Solid Mechanics selected:
Physics tab with Layered Shell selected:
Physics tab with Multibody Dynamics selected:
Physics tab with Thin Layer node selected in the model tree: