Sandwiched cellular structures are light weight structures with high specific, impact, flexuralstrength and stiffness. They are extensively used in several engineering applications like:aeronautics, automobiles, ships, civil engineering, body implants, to name a few. In this study,the performance of hierarchical sandwiched honeycomb core cellular structures undercompressive and impact loads is investigated. Hierarchical patterns are developed byreplacing the hexagonal vertex cells of regular honeycomb with circular cells, see Fig 1. Thisis because, vertex based hierarchy is reported to have mechanical merits and it is an effectiveand reliable design to strengthen conventional honeycomb structures [1]. The out of planeperformance of honeycomb can be enhanced by a hierarchical scheme. Therefore, hierarchicalstructures offer higher load bearing capacity compared to their conventional counter parts.

In this study, the hierarchical structures are designed to withstand higher loads by improvingthe local arrangement of cells. Furthermore, the influence of face sheets against impact loadsis also studied using numerical simulations. Mechanical response of various hierarchicalcellular structures subjected to compressive and impact loads were estimated and compared totheir conventional counterparts. Hierarchy is proposed by varying the order and the level ofthe cells. The first and second level of the hexagonal based honeycomb unit cell is estimatedto withstand 5.43 % and 6.06% more compressive loads. Furthermore, in order to efficientlytransfer the loads from the top and bottom ends to the mid walls of the unit cell, the face sheetis attached at an angle to the axis of unit cell, see Fig 2. Such an arrangement is observed toenhance the load distribution in the honeycomb structures and thus their compressivebehavior.

[1] Li, Z., Wang, Z., Wang, X. and Zhou, W., 2020. Bending behavior of sandwich beam withtailored hierarchical honeycomb cores. Thin-Walled Structures, 157, p.107001.