Unveiling the mechanics of deep-sea sponge-inspired tubular metamaterials: Exploring bending, radial, and axial mechanical behavior

Strengthened tubular structures have had a significant impact on various industries. Advancements in aircraft, construction, medical implants, robotics, and renewable energy have improved safety, efficiency, and durability in multiple sectors. This work explores the practical applications of medical health, using nasal swabs as an example, under different loading scenarios. The study focuses on incorporating bioinspired structural elements, drawing inspiration from the skeletal lattice of sea sponges. By utilizing the sea sponge's process of trial and error in evolution, this bioinspired approach provides a promising perspective on enhancing the mechanical performance of tubular structures. To evaluate the mechanical advantages of the bioinspired design approach, we conducted 3-point bending, radial, and axial compression tests on 3D printed tubular lattice structures. The tests showed that the tubular structure, inspired by sponges, displayed improved bending properties and was approximately twice as stiff as traditional tubular designs. Furthermore, the sponge-inspired design exhibits significantly higher strength and toughness compared to traditional designs, with approximate improvements of 3 and 4 times, respectively. Numerical simulations revealed that these enhancements are attributed to the strengthening effect of diagonally double diagonal struts, which distribute stress evenly and allow for bending without excessive stress concentration. The bio-inspired design shows improved resistance to radial and axial loading, with approximately 1.3 and 3 times greater radial/axial compression stiffness compared to unreinforced designs. These improved mechanical properties of sea sponge-inspired tubular metamaterials make them suitable for a wide range of applications.