In-plane compression of 3D-printed self-similar hierarchical honeycombs – Static and dynamic analysis

In-plane collapse behaviors of second-order wood-inspired hierarchical honeycombs (replace each solid side of a conventional honeycomb with a wall comprising smaller hexagons) under quasi-static and dynamic in-plane compression were examined via experiments and finite element (FE) simulation. Analytical formula for the initial crushing strength and plateau crushing force were also developed. Compared to the conventional honeycomb, a hierarchical honeycomb displays a higher mean post-yield crushing stress, although its specific energy absorption is slightly lower. Their initial phase of energy dissipation is linked to the rotation and shortening/compression of the inclined hierarchical walls. Due to less catastrophic collapse of the smaller first-order cells, the plateau stress phase is more stable and gradual overall hardening is evident in the stress-strain curve. Under dynamic loading, the initial peak force and subsequent plateau force are elevated. There are three types of responses – quasi-static, transition/progressive and dynamic – depending on the magnitude of the impact velocity. •In-plane collapse behaviors of second-order wood-inspired 3D-printed self-similar hierarchical honeycombs were studied.•Digital image correlation (Vic-2D) was employed to identify the strain distribution on the cell walls.•The first-order shear bands and second-order densification zone were firstly proposed.•Analytical formulas for the initial crushing strength and plateau crushing force were developed.•Hierarchical honeycombs display a significantly higher mean post-yield crushing stress than the conventional honeycombs.