Analysing fracture properties of bio-inspired 3D printed suture structures

This research investigates the effectiveness of bio-inspired suture structures in improving the fracture properties of thin 3D-printed plates. Inspired by the interlocked suture joint of the diabolical ironclad beetle, three designs are developed to identify the impact made by variations in size and the number of interlocking points on stabilizing and improving the fracture behaviour of thin, brittle 3D-printed plates. Incorporating a suture joint into a structure helps to control the crack propagation along the suture component, which will be beneficial in predicting the structure's fracture properties. As the mechanical performance of the joint has a great impact on the properties of a thin-walled structure, utilizing sutures can provide light weight joints without external joining techniques. Among various beetle species, the diabolical ironclad beetle has garnered much attention as it can resist crushing forces twice as great as other beetle species. This suture contains interlocking pieces called blades which are ellipsoidal in shape and make the suture structure tougher than those of terrestrial beetles which have triangular or hemispherical blades. Specimens are printed through fused deposition modelling (FDM) using polylactic acid (PLA). The printed structure is thoroughly assessed by microscope and X-ray CT scan analysis. Experimental results are obtained for three different sizes of the suture structure, and a compact tension test is conducted for further examination of the structure's behaviour by utilizing digital image correlation (DIC) and numerical simulation to capture the fracture mechanism and deformation of the suture structure.