Mechanical behaviour of meta-sandwich structures with spinodal-shell core: Modelling, analysis and experiments

Shell-based spinodal architectures have recently attracted significant attention as mechanical metamaterials due to their highly tuneable effective properties. In this work, the suitability of shell-based spinodal metamaterials as core materials for lightweight sandwich structures is investigated. For this purpose, a multiscale computational framework supported by experimental validation is developed. At the small-scale, a computational homogenization approach is employed to evaluate the effective elastic properties of periodic spinodal-shell unit cells, including the effective Young’s and shear moduli along the principal material directions. The adopted homogenization framework evolves from its application on solid-based topologies towards a dedicated framework specifically refined for shell-based architectures. Experimental validation of the homogenized elastic properties is provided through compression tests performed on additively manufactured spinodal-shell unit-cell specimens. At the structural scale, the homogenized properties are integrated into finite element models of sandwich beams to investigate their flexural response under three-point bending. The sandwich specimens, consisting of two face sheets bonded to a core made of an array of shell-based spinodal cells, are manufactured and tested for selected span lengths. The experimental bending results provide quantitative validation of the numerical predictions, enabling a consistent comparison between numerical and experimental flexural stiffness and confirming the capability of the proposed modelling framework to capture the dominant deformation mechanisms governing the bending response. The combined numerical and experimental results demonstrate that shell-based spinodal architectures represent a valid class of sandwich cores, offering favourable stiffness-to-weight performance and design flexibility.