In-plane and out-of-plane compressive performance of bio-inspired 3D printed strain-hardening cementitious composite porous lattice structures

Porous lattice structures are widely used in energy absorption applications due to their excellent energy absorption characteristics. Strain-hardening cementitious composites (SHCC) are promising materials for 3D printed concrete. Inspired by the slender stems of Elytrigia repens, this study designed and fabricated five different types of 3D printed SHCC porous lattice structures: triangular, rectangular, regular honeycomb, auxetic honeycomb, and circular. Compressive tests were conducted in both the in-plane and out-of-plane directions to evaluate their compressive behavior. Compared to the mold-cast solid specimens, the printed porous lattice specimens exhibited superior energy absorption capacity and ductility. Under in-plane loading, the ductility factor of the printed specimens was 3.03–7.47 times higher than that of the mold-cast specimens; while under out-of-plane loading, the specific energy absorption was 1.41–2.57 times higher. A finite element model (FEM) was developed to simulate the compressive behavior of the 3D printed SHCC porous lattice structures, using the concrete plastic damage model and cohesive elements. Based on the developed FEM, the relative density of the five structures was expanded, ranging from 0.31 to 0.79. A power law function was established based on the relative density to predict the mechanical performance of the bio-inspired 3D printed SHCC porous lattice structures. The coefficient of determination for the prediction model ranged from 0.77 to 0.99, with an average of 0.94, indicating that the model accurately reflects the mechanical performance trends of the structures and exhibits high accuracy and reliability.