Geometric Nonlinearity

For geometrically nonlinear studies with the Beam interface, a corotational formulation is used. It takes large displacements and rotations into account, but assumes small strains. This approach differs from what is used in the other structural mechanics interfaces.

The essence of the formulation is that each element in the mesh has a linear formulation within its own frame, but this frame can translate and rotate. The change in angle over a single element is assumed to be small. Thus, the number of elements to use in the mesh will depend on the expected curvature. This stands in strong contrast to linear beam analysis, where the only a single element is needed for each physical beam as long as there are no distributed loads.

A consequence of this formulation is that it is not possible to perform prestressed analysis with the Beam interface.