Global and local linear buckling behavior of a chiral cellular structure

This paper investigates the flat-wise compression behavior of an innovative cellular structure configuration. The considered layout has a hexagonal chiral geometry featuring cylinders, or nodes, joined by ligaments, or ribs. The resulting assembly is characterized by a number of interesting properties that can be exploited for the design of alternative honeycombs or cellular topologies to be used in sandwich construction. The flat-wise strength of the chiral geometry is investigated through classical analytical formulas for the linear buckling of thin plates and shells and a bifurcation analysis performed on a Finite Element model. The analytical expressions predict the global buckling behavior and the resulting critical loads, and can be directly compared with the results obtained from the Finite Element analysis. In addition, the Finite Element model predicts local buckling. modes, which should be considered to evaluate the possible development of localized plasticity. A sensitivity study is performed to evaluate the influence of the geometry of the chiral structure on its buckling strength. The study shows that the considered topology can offer great design flexibility, whereby several parameters can be-selected and modified to improve the flat-wise performance. The comparison with traditional, hexagonal centro-symmetric structural configurations concludes the paper and demonstrates the enhanced performance and the potentials of chiral noncentrosymmetric designs. (c) 2005 WILEY-VCH Vertag GmbH & Co. KGaA, Weinheim.