COMSOL 6.2 - Beam End Release

Beam End Release

In cases where a joint between two or more beams is not perfectly rigid, you can add a node to specify the decoupled degrees of freedom.

If three or more beams meet at the same point, you may need to add an Edge Group subnode in order to specify how the beams are connected to each other. The default is that all beams meeting at a point are independent from each other in the selected degrees of freedom.

Edge Defining the Local Orientation

In the case of a geometrically nonlinear analysis, the orientation of the axes along which one or more degrees of freedom are decoupled may change due to finite rotations.

For cases when rotational degrees of freedom are decoupled, the rotation will however not be the same in all beams attached to a joint. Often this is not an issue since the interesting orientation is still unique, but you have a possibility to explicitly select the edge from which the axis rotations are inferred. The default option is . In this case, the rotation is averaged between all participating edges.

To display this section, click the button (

) and select in the dialog box.

Release Settings

Select the degrees of freedom which are to be decoupled at the selected point. The directions are interpreted along the axes of the selected coordinate system. In a geometrically nonlinear analysis, the coordinate system only gives the orientation in the original configuration. The actual orientation in which the degrees of freedom are decoupled rotates with the beam.


	Adding loads or constraints to a degree of freedom that has been disconnected using Beam End Release may give unintuitive results. Essentially, the degree of freedom value at the point is defined as the average of the values in the disconnected beams. A prescribed displacement will thus act as a constraint equation, prescribing a weighted sum of the displacements or rotations in the connected beams, but not their individual values.


	Nonrigid Joints


	Stress Analysis of a Portal Crane: Application Library path Structural_Mechanics_Module/Beams_and_Shells/portal_crane

Location in User Interface

Physics tab with selected: