Analysis of a geometrically exact multi-layer beam with a rigid interlayer connection

A finite-element formulation for geometrically exact multi-layer beams is proposed in the present work. The interlayer slip and uplift are not considered. The number of layers is arbitrary, and the basic unknown functions are the horizontal and vertical displacements of the composite beam's reference axis and the cross-sectional rotation of each layer. Due to the geometrically exact definition of the problem, the governing equations are nonlinear in terms of basic unknown functions and the solution is obtained numerically. In general, each layer can have different geometrical and material properties, but since the layers are rigidly connected, the main application of this model is on homogeneous layered beams. Numerical examples compare the results of the present model with the existing geometrically nonlinear sandwich beam models and also with the 2D plane-stress elements and, where applicable, with the results from the theory of elasticity. The comparison with 2D plane-stress elements shows that the multi-layer beam model is very efficient for modelling thick beams where warping of the cross-section has to be considered.