Inspired by nature, this study employed the Bouligand structures, as observed in the dactyl club of mantis shrimp, to enhance the performance of 3D-printed Strain-Hardening Cementitious Composites (3DP-SHCC). Twenty sets of printed and mold-cast specimens were prepared to investigate the effects of Bouligand structures on the flexural performance of 3DP-SHCC. Three printing patterns (parallel, cross, and Bouligand printing) and five pitch angles (15°, 30°, 45°, 60°, 75°) were used for the Bouligand printing pattern. The results showed that the flexural performance of parallel-printed SHCC exhibited significant directionality. The flexural strength and toughness of parallel-printed SHCC in the X direction were 1.28 times and 3.27 times greater than the mold-cast SHCC. However, the flexural strength and toughness in the Y direction were 0.58 times and 0.25 times those of the mold-cast SHCC. The cross-printed and Bouligand-printed SHCC alleviated the directionality. The flexural performance of cross-printed SHCC was lower than that of the mold-cast SHCC. Compared to parallel-printed SHCC, the flexural strength and toughness of Bouligand-printed SHCC increased by 1.25 to 1.73 times and 3.48 to 5.10 times, respectively, in the Y direction. Bouligand-printing twisted the fiber angles, enabling effective crack bridging across multiple directions and endowing the SHCC with uniform mechanical properties in various directions. The Bouligand structures provided valuable inspiration for optimizing 3DP-SHCC structures.

中文翻译：

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具有 Bouligand 结构的受自然启发的 3D 打印应变硬化水泥复合材料 (3DP-SHCC) 的弯曲性能

受大自然的启发，这项研究采用了在螳螂虾指节俱乐部中观察到的 Bouligand 结构，以提高 3D 打印应变硬化水泥复合材料 (3DP-SHCC) 的性能。制备了 20 组印刷和模铸样品来研究 Bouligand 结构对 3DP-SHCC 弯曲性能的影响。 Bouligand 印刷图案使用三种印刷图案（平行、交叉和 Bouligand 印刷）和五种间距角（15°、30°、45°、60°、75°）。结果表明，平行印刷SHCC的弯曲性能表现出明显的方向性。平行印刷SHCC在X方向的弯曲强度和韧性分别是模铸SHCC的1.28倍和3.27倍。然而，Y方向的弯曲强度和韧性分别是模铸SHCC的0.58倍和0.25倍。交叉印刷和 Bouligand 印刷的 SHCC 减轻了方向性。交叉印刷SHCC的弯曲性能低于模铸SHCC。与平行印刷的SHCC相比，Bouligand印刷的SHCC在Y方向的弯曲强度和韧性分别增加了1.25至1.73倍和3.48至5.10倍。 Bouligand 印刷扭曲了纤维角度，能够有效桥接多个方向的裂纹，并赋予 SHCC 在各个方向上均匀的机械性能。 Bouligand 结构为优化 3DP-SHCC 结构提供了宝贵的灵感。