Edge to Boundary
Add an Edge to Boundary node to connect a shell edge to a shell boundary in a mesh independent configuration.
This connection is useful in, for example, the following situations:
If possible, use the Edge to Edge coupling, which involves fewer approximations. The Edge to Boundary coupling has the advantage that there is no need for having matching edges in the geometry.
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).
Local edge system
Face Defining the Orientations
This setting is used in conjunction with Local edge system and Shell Local System. When the connection is used for an edge which is shared between boundaries, the coordinate system can be ambiguous. Select the boundary which should define the edge system. The default is Use face with lowest number.
Connection Settings
Select a MethodRigid or Flexible.
For Rigid, the coupling between the two parts is rigid in a pointwise manner. Every point on the destination boundary is coupled by a virtual rigid bar to the nearest point on the source edge. This does not imply that the whole edge is rigid.
For Rigid, select for both the source and destination sides of the connection the Connected location Top surface, Midsurface (default), or Bottom surface.
For Flexible, you supply a stiffness matrix, connecting the corresponding points on the source an destination sides. The stiffness coefficients are given per unit length along the edge. Input fields for the matrices ku,L and kΘ,L are always shown. Select Translational-rotational coupling to show input fields for the coupling matrices kuΘ,L and kΘu,L. In 2D axisymmetry, most elements of these matrices are by definition zero. Only elements which can be nonzero are shown; these are elements 13 and 23 for kuΘ,L, and elements 31 and 32 for kΘu,L.
The stiffness relation can be expressed as
Here, f and m are the forces and moments per unit length acting on the destination side, and Δu is the difference between the destination side displacements and the source side displacements. Similarly, ΔΘ is the difference between the destination side rotations and the source side rotations. All vectors are expressed in the selected coordinate system.
Optionally, you can enter a Mass per unit length, ρu,L. This can for example be the mass of a not modeled weld.
On the boundary, a strip with a certain width is used for the connection. Select a Connected area defined byShell thickness or Distance from shell midsurface to control the width of the strip. The default is Shell thickness, in which case the thickness of the shell on the source side (the edge) is used as the connection width. By choosing Distance from shell midsurface.
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. 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: