Edge to Edge

Add an node to connect two shell edges that are geometrically disjoint. It is assumed that the edges 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:

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You have an imported geometry where there are slits between edges.

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A midsurface generation has left slits between edges.

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You want to avoid the extra flexibility that would be the effect of connecting at the midsurface using a common edge. With this type of coupling, you can take she shell thickness into account in a more accurate way.

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You want to model and evaluate a weld. In that case, you can use the flexible version of the coupling, and evaluate the forces in it.

If there is no good match between two edges, you can as an alternative use the Edge to Boundary coupling.

Coordinate System Selection

Select the coordinate system to use for specifying the stiffness in the case of a flexible connection. From the list select from:

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(the standard global coordinate system).

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	For details about the definition of local edge systems, see Local Edge System.

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Any additional user-defined coordinate system.

Face Defining the Orientations

This setting is used in conjunction with and. 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 .


	This section is available only for edges in the Shell interface and is only visible if the selected coordinate system is Local edge system or Shell Local System.

Connection Settings

Select a — or .

For , the coupling between the two edges is rigid in a pointwise manner. Every node on the destination edge 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. Such a coupling can be obtained using a Rigid Connector.

Select a — or .

For , you supply a stiffness matrix, connecting the corresponding points on the source an destination edges. 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 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 , ρu,L. This can for example be the mass of a not modeled weld.

In order to ascertain that the two edges are parallel, a certain tolerance is used when comparing the angles between them. You can modify this tolerance. Select a — or . For, Δ, enter the maximum angle between the edges.

Constraint Settings

To display this section, click the button (

) and select in the dialog box. The information in this section i sonly used if is set to .

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

Location in User Interface

Context Menus

Ribbon

Physics tab with selected: