Flexural performance of nature-inspired 3D-printed strain-hardening cementitious composites (3DP-SHCC) with Bouligand structures

Abstract

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.