Active face prismatic positional finite element for linear and geometrically nonlinear analysis of honeycomb sandwich plates and shells

In this paper, we propose an original FEM strategy to consider stiffening honeycomb-shaped cells, filled or not, to the simulation of sandwich plates and shells. The strategy combines three-dimensional membrane elements (called active face) with solid prismatic elements. This approach is different from the usual ones that use solid elements to discretize all parts of a panel or use equivalent macroscopic properties to simulate honeycomb-shape laminated composites. In the proposed technique, the composition of elements is done by means of direct nodal correspondence, defined in the mesh generation procedure, not interfering in the number of degrees of freedom of the models. Thus, introduction of reinforcements does not increase the number of degrees of freedom, which makes the technique highly economical from the numerical point of view. Positional finite element (Positional FEM) procedure is adopted, resulting in a total Lagrangian description that allows general applications including large displacements of laminated plate and shell problems. Positional FEM adopts as main variables the current nodal positions instead of displacements as classical finite elements do. The proposed stiffening cell element is tested regarding stress and displacements calculations, comparing results with literature. Results for large displacements in reinforced honeycomb laminated shells are also presented.