Bio-inspired jigsaw-interlocking suture interfaces for enhanced flexural response of 3D-printed strain-hardening cementitious composites (3DP-SHCC)

The natural jigsaw-interlocking suture interfaces of the exoskeletal forewings (elytra) of the diabolical ironclad beetle, Phloeodes diabolicus , exhibit excellent mechanical response, enabling efficient load transfer and energy dissipation. Inspired by these natural jigsaw-interlocking suture interfaces, a groove structure with prefabricated interlocking sutures in 3D-printed Strain-Hardening Cementitious Composites (3DP-SHCC) was systematically studied to investigate the influence of suture geometries on load transfer efficiency, crack propagation paths, and failure modes, revealing the unique energy dissipation mechanism and exceptional deformation capacity of the jigsaw-interlocking suture. Experimental results show that bio-inspired jigsaw-interlocking sutures can significantly enhance flexural strength and energy dissipation, and delay suture interface failure through an interlocking mechanism. The optimized suture geometries (engagement angle = 25°; elliptical aspect ratio = 1.8) achieve synergistic optimization of flexural strength, ductility, and energy dissipation. Compared with its cast unjointed counterpart, specimen Y-A 25° G 1.8 retained 97.2% of the flexural strength and 94.0% of the total energy dissipation, indicating comparable mechanical performance without supplementary reinforcement. These findings challenge the conventional assumption that joints inherently compromise mechanical performance. The suture interface with nonlinear mechanical response provides a novel bio-inspired approach for the engineering joint design, holding significant application potential in the fields of earthquake resistance and prefabrication assembly. • A novel suture strategy is proposed to enhance joint mechanical performance in 3DP-SHCC. • Four failure modes of 3DP-SHCC suture joints are identified based on suture geometry. • Optimal suture geometry ( α = 25°, λ = 1.8) synergistically enhances strength, ductility, and energy dissipation. • Weak interlayer interfaces in the X-printing direction reduce interlocking effectiveness. • The jigsaw-interlocking suture challenges the conventional assumption that joints compromise structural performance.