Influence of design parameters on the flexural properties of a bio-inspired suture structure

Among various bio-inspired structures, sutures are a prominent structure which has evolved independently to optimize their functionalities. The diabolical ironclad beetle suture-inspired structure was fabricated using multi-material additive manufacturing (3D printing) system with TangoBlackPlus (TBP) as the soft suture layer and VeroWhitePlus (VWP) as the hard material. The print quality of the specimen was assessed through the optical microscope images, and a nanoindentation test was performed to investigate the interfacial hardness between TBP and VWP. Flexural properties of the suture structure when changing the thickness of the soft layers were then studied. Experiments were continued to identify the effect of combining different sizes of suture modules to develop the suture structure. A numerical simulation model was then generated and validated using the experimental results to proceed with the parametric study. A design of experiment (DoE) was developed to analyse the effect of changing the suture geometry to optimize performance. The research concluded that gradually decreasing the size of the suture allowed the structure to withstand higher loads. It was also evident that the deformability of the structure could be increased by incorporating smaller interlocking angles and larger a:b ratios, while larger interlocking angles and smaller a:b ratios generate stiff structures.