Bio-inspired novel joints with superior mechanical performance

Abstract

Joining metals and polymers in engineering applications remains a significant challenge, among which interlocking joints offer a promising solution. Nonetheless, conventional interlocking joints often suffer from outward bending of the female part, leading to the disengagement of joining components. This study introduced novel interlocking joint designs such as humps scarf joints and humps wavy joints, which incorporate the main and auxiliary interlocking features to enhance the mechanical performance of aluminium–nylon joints. Our experimental tests demonstrated that our designed novel joints remarkably outperform conventional designs in terms of ultimate tensile strength, initial stiffness, and toughness. In particular, the humps scarf joint achieved an ultimate tensile strength of 22.6 MPa, which was 1.39, 1.45, 1.71, 4.61, and 5.95 times higher than those of the humps wavy, T-slot, elliptical, original dovetail, and adapted dovetail joints, respectively. Using joint strength normalised by the polymer’s bulk tensile strength, the best-performing injection-moulded aluminium–nylon joint in the recent literature reached the highest normalised joint strength value of 0.31, while our humps scarf joint ranked the second at 0.27 among 12 joints investigated. Accordingly, the design of two novel interlocking joints is effective for various engineering applications owing to their ease of fabrication and assembly, as well as superior strength, stiffness, and toughness.