Energy-based strut stress analysis of 3D lattice cores in sandwich panels

3D strut-based lattices consisting of periodic representative volume elements (RVE) have gained more importance over the last few years since they provide outstanding mechanical performance and an efficient design in lightweight engineering. In sandwich panels, strut-based lattices may replace the established honeycomb cores. In this study, an analytical model is introduced to investigate 3D strut-based lattice cores of sandwich panels. Body-centered cubic and face-centered cubic RVEs reinforced by vertical struts (BCCZ and F2CCZ) are considered as sandwich cores. Since the core stiffness is generally low in comparison with the face sheet stiffness, the derived model considers through the thickness stresses in the core caused by transverse concentrated loads, which are not obtained by the common sandwich theories. Furthermore, stress concentrations near the support points are sufficiently captured thanks to higher-order displacement representations. The analysis of the core behavior is based on the homogenization and dehomogenization of the lattice core methods. Compared with the finite element analysis, the stresses in the lattice struts are determined by the proposed model with ten times less computational effort and adequate accuracy, particularly in the highly loaded vertical struts.