Out-of-Plane Mechanical Behavior of 3D-Printed Polymeric Circular-Vertex-Based Hierarchical Hexagonal Honeycombs

Many studies show that hierarchical honeycombs have a superior performance compared to regular honeycombs. However, relevant experimental studies are limited due to the fabrication challenges of hierarchical honeycombs featuring complex geometries. In this study, circular-vertex-based hierarchical hexagonal honeycombs (CHHHs) with different hierarchical parameters were fabricated using a polymeric 3D-printing technique, and their quasi-static out-of-plane mechanical behavior was investigated. The CHHHs were constructed by replacing each solid vertex of a regular hexagonal honeycomb (RHH) with a circular vertex. Quasi-static compression tests were conducted on CHHHs, and the effect of the hierarchical parameter on the deformation modes, mechanical properties, and energy absorption characteristics was investigated. The results revealed that both the CHHH and RHH specimens experienced cell wall fractures during compression, while the CHHH exhibited enhanced damage resistance, compressive strength, and specific energy absorption (SEA) compared to RHH. This study contributes to understanding the effect of circular-vertex-based hierarchy on the out-of-plane mechanical behavior of regular honeycombs.