This paper illustrates a new modeling approach for planar linear elastic beams.
Referring to existing models, we first introduce the variational principles that could
be adopted for the beam model derivation, discussing their relative advantages and
disadvantages. Then, starting from the Hellinger–Reissner functional we derive some
homogeneous and multilayered beam models, discussing some properties of
their analytical solutions. Finally, we develop a planar beam finite element,
following an innovative approach that could be seen as the imposition of
equilibrium in the cross-section and compatibility along the axis. The homogeneous
model is capable of reproducing the behavior of the Timoshenko beam, with
the advantage that the shear correction factor appears naturally from the
variational derivation; the multilayered beam is capable of capturing the
local effects produced by boundary constraints and load distributions; the
finite element is capable of predicting the cross-section stress distribution
with high accuracy, and more generally the behavior of planar structural
elements.
Keywords
laminated linear elastic beam, analytical solution, finite
element modeling, mixed variational formulation