Hierarchical anisogrid cylindrical shells: Design, additive manufacture and imperfection analyses

Abstract

Anisogrid cylindrical structures (ACS) are widely used in aerospace applications as load-bearing components, but their susceptibility to local buckling and the need for thicker skins in larger structures pose challenges for lightweight design. To address these limitations, this study proposes a hierarchical anisogrid cylindrical shell (HACS) with fractal skin, fabricated using laser powder bed fusion (L-PBF). The mechanical properties and failure modes of HACSs with varying volume fractions were compared to those of traditional anisogrid cylindrical shells (TACSs) through experimental, finite element modeling (FEM), and theoretical analyses. The results reveal that the hierarchical design significantly improves buckling resistance and load-bearing capacity, with the fractal skin enabling a transition from elastic to plastic failure modes at low volume fractions and increasing load capacity by 53.12 %. Manufacturing defects were found to reduce mechanical performance, particularly in the fractal skin, while a size-corrected FEM demonstrated strong agreement with experimental data. A theoretical failure analysis model was also developed to predict structural deformation, offering a reliable tool for evaluating lattice cylinder performance. This study aims to provide new insights into the means of enhancing the bearing capacity of lattice cylinders through the application of hierarchical design and additive manufacture.