Mechanical Properties of <scp>4D</scp> Printed Origami Honeycomb Metamaterials Based on Nano‐ <scp> Fe ₃ O ₄ </scp> Shape Memory Polymer Composites

ABSTRACT To address the limitations of traditional honeycomb structures in energy absorption applications, such as irreversibility after deformation and lack of reusability, a novel Miura‐ori‐based origami honeycomb metamaterial was fabricated from a Fe 3 O 4 nanoparticle‐embedded shape memory polymer composite via 4D printing. Characterization of the matrix material demonstrates that Fe 3 O 4 nanoparticle incorporation markedly improved tensile strength and elastic modulus and achieved excellent shape fixity (&gt; 99%) and recovery (&gt; 96%). The energy absorption performance of the structure was systematically evaluated, including comparisons with traditional honeycombs, variations in nanoparticle content, geometric configurations, and cyclic compressive loading. The results show that the origami honeycomb exhibits a smoother force‐displacement response and more stable deformation during the plateau stage than traditional counterparts. An optimal Fe 3 O 4 concentration (6 wt%) ensures favorable energy absorption and deformation behavior. Increasing cell spacing, folding angle, and layer number significantly enhances both energy absorption (EA) and specific energy absorption (SEA). Under cyclic compression at 50% strain, the structure retains 21.22% of its initial energy absorption in the fourth cycle. It absorbs 8.05 J of EA and achieves a SEA of 0.39 J/g. At the end of compression, the structure bears a load of 1.48 kN, demonstrating repeatable energy absorption capability.