The Beam (beam) interface (), found under the Structural Mechanics branch () when adding a physics interface, is used for modeling slender structural elements, having a significant bending stiffness. The formulation allows geometric nonlinearity, with large rotations and small strains, and beams can be modeled on 2D boundaries and 3D edges.

Among the computed results are displacements, rotations, stresses, strains, and section forces. In addition to giving the beam properties explicitly in terms of area, moment of inertia, and so on, several predefined common cross-section types are available. Cross-section data to be used in Cross-Section Data settings can be computed using The Beam Cross Section Interface.

When this physics interface is added, these default nodes are also added to the Model Builder: Linear Elastic Material, Cross-Section Data, Free (a condition where points are free, with no loads or constraints), and Initial Values. Then, from the Physics toolbar, add other nodes that implement, for example, loads and constraints. You can also right-click Beam to select physics features from the context menu.

The Label is the default physics interface name.

The Name is used primarily as a scope prefix for variables defined by the physics interface. Refer to such physics interface variables in expressions using the pattern <name>.<variable_name>. In order to distinguish between variables belonging to different physics interfaces, the name string must be unique. Only letters, numbers, and underscores (_) are permitted in the Name field. The first character must be a letter.

The default Name (for the first physics interface in the model) is beam.

From the Structural transient behavior list, select Include inertial terms (the default) or Quasistatic. Use Quasistatic to treat the dynamic behavior as quasi static (with no mass effects; that is, no second-order time derivatives). Selecting this option gives a more efficient solution for problems where the variation in time is slow when compared to the natural frequencies of the system. The default solver for the time stepping is changed from Generalized alpha to BDF when Quasistatic is selected.

Enter the default coordinates for the Reference point for moment computation xref. The resulting moments (applied or as reactions) are then computed relative to this reference point. During the results and analysis stage, the coordinates can be changed in the Parameters section in the result nodes.

In the Sketch section, a conceptual sketch of the degrees of freedom in the Beam interface is shown.

Select Euler-Bernoulli or Timoshenko to use the appropriate beam theory. Timoshenko theory includes the effects of shear flexibility and rotary inertia, and is appropriate for beams with cross-section dimensions which are large relative to the length of the beam.

This section will only be displayed if a mesh on NASTRAN® format, containing RBE2 elements, has been imported in an Import node under Mesh. The purpose is to automatically create rigid connectors from RBE2 elements in the NASTRAN file.

In the drop-down menu in the section title, you can select Create Rigid Connectors from RBE2. The effect is that one rigid connector will be created for each RBE2 element in the imported file. This will happen for all physics interfaces in the Interfaces list. Supported interfaces are: Solid Mechanics, Shell, Beam, and Multibody Dynamics. If there are RBE2 elements spanning more than one physics interface, they will be automatically connected.

The Automated Model Setup section is present in the Solid Mechanics, Shell, and Beam interfaces. In a model that contains several physics interfaces, you should use the automated model setup from only one of them, and make sure that all the involved interfaces are selected in the Interfaces list.