On mechanics of interlocking structures by a sickle joint

Abstract

In recent years, attention has focused on the excellent mechanical properties of bones, teeth, and crustaceans. In particular, interlocking tissue is strongly interested as one of the characteristics of the microscopic structure of crustaceans. The interlocking structure has sutures like puzzle pieces, and friction slip in the pull-out process occurs at the sutures by subjecting to a tensile load. As a result, it is recognized that the toughness is apparently improved. By the way, in wooden houses in Japan, iron nails are not used, but the mortise-neck joints are used to fasten timbers together. The feature is that the fastening force can be freely controlled by adjusting the angle of the suture. Therefore, in this study, we simulate the bioinspired interlocking structure by these sickle joints and develop a mechanical model based on the pull-out mechanism for this structure. In order to verify the validity of the developed model, we compared it with the finite element analysis results. Furthermore, we investigated the effect of the suture shape on the relationship between load and displacement. It was clarified that the suture shape and interfacial friction coefficient affect the maximum load and elongation at break. Finally, the relationship between the fracture energy estimated from the relationship between load and displacement and these parameters was summarized as a map.

Keywords

• toughness
• biomimetics
• sickle joint
• interlocking structure
• pull-out mechanism
• load-displacement curve
• fracture energy
• joint mechanics