Unraveling the performance mysteries of bionic triangular heterogeneous suture interfaces

• Mimics stickleback fish sutures for optimized stress distribution. • Combines rigid (VeroPureWhite) and soft (Agilus) polymers. • Stiffness, strength, toughness adjust via suture angle (θ) and material ratios. • Up to 10× stiffness and 88× toughness gains over conventional interfaces. • Balances tensile strength and bending adaptability for biomedical/aerospace use. Natural suture structures offer significant advantages in improving the mechanical properties of interfaces. However, current research mainly focuses on the suture structures formed by the interlocking of two homogeneous hard materials through a soft material interface. Inspired by the triangular suture pattern, which is known to enhance stiffness, strength, and uniformity of stress distribution, this study investigates the application of the triangular suture concept to heterogeneous material interfaces. Herein, we develop a novel biomimetic triangular heterogeneous suture interface and corresponding composite materials. The influence of suture frequency and material properties on mechanical behavior is investigated through tensile tests, three-point bending, and finite element analysis. The mechanical properties of the above materials can be modulated within one order of magnitude by adjusting the aforementioned parameters. By adjusting the aforementioned parameters, the composite’s flexural flexibility can be improved while maintaining its tensile properties, for example, when the soft material is Ag95 and θ = 45°. The mechanical properties of the suture interfaces can be customized using the fitting curves, equations, and bio-inspired design strategy proposed in this study. This research has significant implications for advancing bio-mimetic heterogeneous materials and provides innovative insights into designing artificial interfaces, such as bio-inspired engineering graft scaffolds.