Bio-inspired variant honeycomb structures via 4D printing: Revolutionizing the realm of energy absorption

Abstract

Conventional hexagonal honeycomb structures face limitations in post-fabrication adaptability and energy absorption tunability. In this study, we propose a bionic variant honeycomb (BVH) structure based on 4D printing, which achieves shape-property synergistic modulation by incorporating shape memory polymers (SMP). Based on the vertex reconfiguration strategy, concave, quadrilateral-like and flattened hexagonal honeycomb cells are designed, and the energy dissipation paths are optimized through combinatorial and hierarchical configurations. Poly(lactic acid) (PLA)-based honeycomb structures are prepared by fused deposition molding technique, which is combined with thermo-mechanical programming to achieve the programming of temporary shapes and reach the intelligent regulation of energy absorption capacity, e.g., the specific energy absorption is reduced by 55.7 % at 30 % pre-strain. Experiments and finite element simulations show that the hierarchical configuration significantly improves the energy absorption efficiency. This study innovatively combines 4D printing with biomimetic design to give the honeycomb structure the adaptive ability to actively respond to external stimuli after fabrication, providing a new paradigm for the development of smart energy-absorbing metamaterials. This research will show a broad application prospect in the fields of automobile collision protection and aerospace.