Use beam or link (truss) elements to represent relatively long, thin pieces of structural continua (where two dimensions are much smaller than the other dimension).

Beam elements assume the direct stresses in the nonaxial direction to be zero, and ignore the deformations in the nonaxial directions (although cross sections can be scaled in a nonlinear analysis). For link elements, shear stress, stress gradients, and deformation are also ignored.

Simulating beam/truss structures is relatively simple, as elements can be created by meshing lines or curves representing the position and shape of the structure (rather than by meshing the volumes). The elements are associated with section data to represent the beam or truss cross sections.

Although beams can be used in cases where link/truss elements suffice, they are not as computationally efficient as link elements.

The available beam element types are:

Both elements are based on Timoshenko beam theory which includes shear-deformation effects. The elements can account for unrestrained warping and restrained warping of cross-sections.

Because bending resistances, element loads, or both are normally different in the y and z directions, a beam element must be oriented about its own axis. Typically, the orientation is accomplished via an orientation node, a node not lying on its own axis.

If bending resistance is negligible, consider using LINK180, a 3-D spar (or truss).