A team of American researchers recently unraveled the secrets of the extraordinary resistance of the “evil iron-headed beetle”, an armored beetle capable of surviving two passages under the wheels of a 1.6-ton vehicle.
Resistance to (almost) any test
During experiments carried out in 2015, scientists fromPurdue University had noticed that Nosoderma diabolicum could survive two successive crushings by a Toyota camry. Recently featured in the journal Nature, their new work specifically focused on the incredibly robust exoskeleton of this beetle species, to determine how this structure could withstand such stresses.
Relying on different high-resolution imaging techniques and the use of compressed steel plates, the team was able to observe the behavior of the beetle’s exoskeleton under increasing pressures and found that the structure could support loads. 39,000 times the total weight of the creature before it cracked, which equates to a force exerted of about 150 newtons.
The researchers then used computer simulations and 3D printed models to isolate the different structures of the exoskeleton in detail, which made it possible to highlight the role of a connective suture extending over the entire body. length of the beetle’s abdomen.
Located between the two elytra (envelopes used to protect the wings in species by being provided) of the beetle, the suture connects them to the blades of the exoskeleton, located just below, thus helping to evenly distribute the forces applied to the body of the insect through two complex processes.
Like the pieces of a puzzle, the blades of the exoskeleton fit into each other, preventing them from being torn off by strong force. During this time, the suture and the blades divide into concentric layers. These two mechanisms work together to distribute the load on the beetle and prevent fatal fractures in its neck.
Rigid and resistant materials inspired by the beetle
According to the researchers, relying on such an approach would prove particularly useful for the design of gas turbines for airplanes, where metals and composite materials must be combined using heavy mechanical fasteners which can generate significant tensions and stresses. over time, inducing a risk of cracking.
Tests carried out on a prototype of carbon fiber composite attachment, based on the structure of the exoskeleton of the evil beetle, showed that it had a resistance similar to the beetle envelope, proving to be much greater than that of the fasteners currently used in the aerospace industry.
” This work shows that we could move from the use of rigid and brittle materials to materials that are both rigid and resistant, which dissipate energy when subjected to high stresses. », Concludes Pablo Zavattieri, lead author of the study. ” This is precisely the ability with which nature endowed the evil iron-headed beetle.. “