Boundary to Boundary
Add a Boundary to Boundary node to connect two shell boundaries that are geometrically disjoint. It is assumed that the boundaries are parallel. The connection between corresponding points on the two edges can be rigid or flexible.
This connection is useful in, for example, the following situations:
The mesh does not have to be the same on both boundaries, but there will be less local stress fluctuations if it is.
Coordinate System Selection
Select the coordinate system to use for specifying the stiffness in the case of a flexible connection. From the Coordinate system list select from:
Global coordinate system (the standard global coordinate system).
Connection Settings
Select a Connection typeRigid or Flexible.
For Rigid, the coupling between the two boundaries is rigid in a pointwise manner. Every node on the destination boundary is coupled by a virtual rigid bar to the nearest point on the source boundary. This does not imply that the whole boundary is rigid. Such a coupling can be obtained using a Rigid Connector.
For Flexible, select Connection propertiesUser defined or From material.
For User defined, enter the Spring constant per unit area. This is a matrix K, coupling the displacements on the two sides.
Here, f is the force acting on the destination side, and Δu is the difference between the destination side displacements and the source side displacements. All vectors are expressed in the selected coordinate system.
Optionally, you can enter a Mass per unit area, ρu,A. This can for example be the mass of a glue layer.
In all cases, select the Source boundary and Destination BoundaryTop or Bottom. The information is used for two purposes: to connect to the correct set of displacements, and to compute the distance, including the shell thickness and offset.
The two boundaries are only connected if they are within a certain tolerance from touching each other. The distance is computed including shell thickness and offset, as well as the selected connection boundaries. You can modify this tolerance. Select a Connection toleranceAutomatic or User defined. For User defined, enter the maximum allowable distance or overlap between the boundaries, δ.
Constraint Settings
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box. The information in this section i sonly used if Method is set to Rigid.
In the COMSOL Multiphysics Reference Manual:
Location in User Interface
Context Menus
Ribbon
Physics tab with Shell selected: