RVE-based grading of truss lattice cores in sandwich panels

Additive manufacturing enables the fabrication of strut-based lattices that consist of periodic representative volume elements (RVE) and can be used as cores in sandwich panels. Due to the design freedom provided by additive manufacturing, the lattice strut diameter may vary through the lattice. Thus, the diameter distribution can be adapted to the stress variation in the sandwich core to achieve an efficient core design and avoid oversizing the core. Such grading approaches are required when the core is subjected to localized loads, e.g., near support points and load application areas. In this work, an analytical model is derived to determine stresses and deformations in lattice struts of RVE-based graded lattice cores in elastic sandwich panels using homogenization and dehomogenization methods. In contrast to already available models, the analytical model presented in this work allows grading the lattice strut diameter both along the sandwich length and through the core thickness. Furthermore, local stresses in the lattice struts caused by concentrated load application can be captured adequately by the present model. To highlight the benefits of graded cores, the strut stress distribution in graded cores is compared to the stress distribution in homogeneous cores.