Bio-Inspired Bouligand Architectures for Enhanced Flexural Performance in 3D-Printed Strain-Hardening Cementitious Composites (3DP-SHCC) (2025-08)¶

Natural organisms such as mantis shrimp dactyl clubs and coelacanth fish scales have evolved natural damage-resistant biological helical microstructures, such as single- and double-bouligand architected models, which are considered unique and promising biological structures, providing innovative inspiration for high-performance architectural design. Inspired by the bouligand architecture, robotics additive manufacturing technology has been successfully used to manufacture 3DP-SHCC laminates with single- and double-bouligand architectures, aiming to develop their inherent excellent mechanical behavior and toughness mechanism. Compared to the corresponding cast counterparts, the single-bouligand architected 3DP-SHCC laminates with a small pitch angle have increased cracking load, peak load, and energy absorption by 71.5%, 72.6%, and 98.1%, respectively, while the specimens with double-bouligand architectures significantly improved cracking load and peak load by 22.2% and 57.2%, respectively. By developing the unique helically layered bouligand architecture, the 3DP-SHCC laminates effectively suppress damage localization and activate multiple toughening mechanisms—including crack bifurcation, twisting, and deflection—thereby achieving a synergistic enhancement of both strength and toughness. This study develops a strain-hardening-based framework to evaluate the flexural toughness of 3DP-SHCC laminates and systematically clarifies the fiber directionality contribution rate throughout the entire loading process. The advancement overcomes the long-standing limitations of conventional concrete’s tensile properties, complementing the traditional concrete design and construction concepts under solely compressive conditions. The study combines the biological wisdom of the helically layered bouligand architecture with the intrinsic characteristics of 3DP-SHCC, revealing the enhanced mechanical behavior and toughening mechanism of single- and double-bouligand architectures, offering valuable tools for damage-tolerant design in engineering applications.