Solid-Beam Connection
Add the Solid-Beam Connection multiphysics coupling node () to create transitions between domains modeled using the Solid Mechanics or Multibody Dynamics interfaces and edges modeled using the Beam interface.
The 2D and 3D versions of the Solid-Beam Connection are fundamentally different, and are treated separately below.
Coupled Interfaces
Select Solid mechanics Solid Mechanics or Multibody Dynamics.
Select the Beam interface to couple.
Connection Settings 2D
Select the Connection typeSolid boundaries to beam points, Solid and beam shared boundaries, or Solid and beam parallel boundaries.
In first two cases, there is an automatic search for possible adjacent geometrical objects. If you want to modify the selections, select the Manual control of selections check box. If you clear it again, the selections will be replaced by the automatic ones.
Solid Boundaries to Beam Points
For a manual selection, select the connected solid boundaries in the Boundary Selection, Solid section and the corresponding beam points in the Point Selection, Beam section.
Select Connected area defined by Section height, Selected boundaries, or Distance from beam axis. This parameter determines how much of the selected solid boundaries that are actually connected to the beam. The default is that a distance from the beam point having the size of the half the beam section height in each direction is connected. Using Selected boundaries connects the entire selected boundaries to the beam. If you select Distance from beam axis, enter a Distance d. This is used instead of the section height for defining the connection distance.
Select a Method Rigid or Flexible. The Rigid version of the coupling only adds constraints to the boundary of the solid, which in general causes local disturbances of the stress field, since the thickness cannot change. When using the Flexible coupling, three extra degrees of freedom are added to each beam point. This allows for a more accurate description of the transition, but the model can in some cases become unconstrained if the mesh on the solid is very coarse.
When the connected area is determined by either the Section height or Distance from beam axis options, the connected area is slightly extended by a distance Δ. Select how to determine this Connection tolerance Automatic or User defined. For Automatic, the tolerance Δ is set to 0.5% of the beam height, which allows for small inaccuracies on for example a curved geometry. By selecting User defined, you can modify the value of Δ.
Solid and Beam Shared Boundaries
If the automatic selection is not sufficient, select the Manual control of selections check box. Then, select the connected boundaries in the Boundary Selection section.
The connected area is slightly extended by the distance Δ. Select how to determine this Connection tolerance Automatic or User defined. The Automatic option sets the value of the tolerance Δ to 0.5% of section height of the beam. By selecting the User defined option, you can modify the value of the tolerance Δ.
Solid and Beam Parallel Boundaries
Select the connected solid boundaries in the Boundary Selection, Solid section and the corresponding beam edges in the Boundary Selection, Beam section.
Select Distance evaluationSection height, Geometrical distance, or User defined. This parameter determines how the coupling treats the determination of the connection distance, used when expressing th coupling between translation and rotation. The default is that a distance equal to half the section height is used. If you select Geometrical distance, the connection distance is computed from the geometrical distance between the solid boundary and the beam boundary. For User defined enter a Distance d. This defines the connection distance.
The connected area is slightly extended by a distance Δ. Select how to determine this Connection tolerance Automatic or User defined. For Automatic, the tolerance Δ is set to 0.5% of the beam height, which allows for small inaccuracies on for example a curved geometry. By selecting User defined, you can modify the value of Δ.
Connection Settings 3D
Select the Connection typeSolid boundaries to beam points, general, Solid boundaries to beam points, transition, or Solid boundaries to beam edges. For the connections to beam points, there is an automatic search for possible adjacent geometrical objects. If you want to modify the selections, select the Manual control of selections check box. If you clear it again, the selections will be replaced by the automatic ones.
Solid Boundaries to Beam Points, General
Select this when the end of a beam is to be “welded” to part of the face of a solid domain.
If the automatic selection is not sufficient, select the Manual control of selections check box. Then, select the connected solid boundaries in the Boundary Selection, Solid section and select the corresponding beam points in the Point Selection, Beam section.
Select a Connected region Selected boundaries, Distance (Automatic), Distance (Manual), or Connection criterion.
Using Selected boundaries makes all selected boundaries to be rigidly connected to the point on the beam.
For Distance (Automatic), all parts on the solid boundary, which are within the default distance from the beam point, are connected. This distance is determined by the cross section properties of the beam. It is contained in the variable beam.re as described in the documentation for The Beam Interface.
For Distance (Manual) enter a Connection radius rc. All parts on the solid boundary, which are within the given distance from the beam point, are connected.
For Connection criterion enter a Boolean expression in the text field. The beam is connected to the selected solid boundaries, wherever the expression has a nonzero value. The default value is 1, which is equivalent to using the Selected boundaries option.
Solid Boundaries to Beam Points, Transition
Use this option if you want to model a transition from a beam modeled by solid elements to the same beam modeled using beam elements. It is assumed that the solid part is truncated by a set of boundaries which are perpendicular to the beam axes. No settings other than the selections are needed in this case.
If the automatic selection is not sufficient, select the Manual control of selections check box. Then, select the connected solid boundaries in the Boundary Selection, Solid section and select the corresponding beam points in the Point Selection, Beam section.
This coupling introduces a set of extra degrees of freedom, which preferably should be solved for only once, and separately. If they are solved at the same time as the general problem, you can expect that the solution time increases by a factor of two. For more details, see Beam Point to Solid (3D) in the Structural Mechanics Modeling chapter.
Solid Boundaries to Beam Edges
Use this option when you want to model a beam that is parallel to the solid boundary and is “welded” to it.
Select a Connected region Selected boundaries, Beam width, or Connection criterion.
Using Selected boundaries makes all selected boundaries to be rigidly connected to the point on the beam. This is mainly useful if the boundary has approximately the same shape as the physical size of the beam, such as a rectangle with the same width as a beam flange.
For Beam width, enter a Width w. All parts on the solid boundary, which are within the given distance from the projection of the beam axis on the solid, are connected. For cases when the beam is asymmetric, that is when the connection distance from the beam axis is not the same in both directions, enter also an Offset d. The positive orientation of the offset is , where n is the outward normal of the solid, and t is the positive orientation of the beam edge.
For Connection criterion enter a Boolean expression in the text field. The beam is connected to the selected solid boundary, wherever the expression has a nonzero value. The default value is 1, which is equivalent to using the Selected boundaries option.
When there are many interconnected constraints, it may also be useful to change Null-Space Function to Orthonormal or Explicit — Orthonormal, but doing so may increase the memory consumption significantly.