An international research team consisting of Tokyo University of Agriculture and Technology, California University, etc. has adopted the exoskeleton of Phloodes diabolicus, which is also called "Ironclad beetle" because it has a exoskeleton that is strong enough not to be crushed by a car. Analysis revealed a previously unknown structure and mechanism of robustness.

　First, when the strength of the exoskeleton of P. diabolicus was examined, it was found that it could withstand a load of about 39,000 times its own weight (more than twice that of closely related beetles).From the observation of the destruction of the exoskeleton, it was considered that the layered structure constituting the exoskeleton plays an important role in this robustness.

　Then, when we analyzed the microstructure and constituents of the exoskeleton, we found that only one pair of exoskeletons of other beetle species was found. Then I found two pairs.In the composition of the exoskeleton, the proportion of protein was about 1% higher than that of other beetles, and it was speculated that this was involved in the robustness of the exoskeleton and the formation of special structures.

　Furthermore, in this study, a biomimetic structure that imitated two pairs of uneven structures existing at the exoskeleton junction of P. diabolicus was prepared using a carbon sheet, and compared with the mode used for joining current aviation materials. Even so, it was demonstrated that the members can be firmly joined.

　In the process of evolution, P. diabolicus is thought to have acquired a robust exoskeleton with a special structure and composition instead of having no wings to escape from predators.The structure of the exoskeleton found in this research is expected to be applicable to the design of robust and lightweight members in various fields such as automobiles and aircraft.

Paper information:[Nature] Toughening mechanisms of the elytra of the diabolical ironclad beetle