Biomimetic 3D printed Herringbone-Bouligand SHCC for ultra-high impact resistance

Nature can create tough and lightweight materials under specific conditions. Learning from nature and developing novel biomimetic structures within synthetic materials is crucial for advancing impact-resistant materials. In this work, inspired by the dactyl club of mantis shrimp, we integrated Herringbone and Bouligand structures to produce 3D printed Strain-Hardening Cementitious Composites (SHCC) with ultra-high impact resistance. Through 3D concrete printing, SHCC filaments and fibers were arranged coaxially and form a Herringbone-Bouligand structure. The results indicated that the Herringbone-Bouligand structure significantly enhanced the impact resistance of SHCC. The Herringbone-Bouligand structure exhibited the highest specific absorption energy of 843.3 ± 45.19 mJ/cm 3 and a specific impact force of 23.8 ± 1.17 N/cm 3 . Its specific absorption energy was 290.8 times greater than that of plain concrete (2.9 ± 0.08 mJ/cm 3 ), while its specific impact force was 7.0 times higher than that of plain concrete (3.4 ± 0.05 N/cm 3 ). The toughening mechanism was attributed to the sinusoidal arrangement of the SHCC filaments, which absorbed the impact force through spring deformation, and the Bouligand arrangement, which promoted crack twisting. This combination allowed the structure to better absorb and release energy. The Herringbone-Bouligand structure offers a promising solution for protective applications in harsh environments and provides valuable insights for developing impact-resistant, lightweight cementitious materials through biomimetic strategies.