Beetles that can survive in car tires may inspire hard materials

Researchers report that the demonic iron beetle can survive shattering, which helps to develop new materials with the same toughness.
According to a new study in Nature, these materials will be as hard as paper clips but malleable, making machinery such as aircraft gas turbines safer and more durable.
Studies have found that the super toughness of the demonic iron beetle lies in its two armor-like “elytrons”.
Among flying beetles, Coleoptera protects the wings and promotes flight. But the demonic iron beetle has no wings. Conversely, sheath threads and connective sutures can help distribute force more evenly throughout the body.
The act of stitching is like a jigsaw puzzle. It connects various exoskeleton blades (puzzle pieces) to the abdomen under the sheath. “Purdue University civil engineering professor Pablo Zavattieri said. He said that depending on the amount of force applied, the jigsaw puzzle can be solved in several different ways.
To reveal these strategies, a team led by David Kisailus, a professor at the University of California, Irvine, studied CT scans to first test the limits of the beetle’s exoskeleton and characterize the various structural components involved.
Using compressed steel plates, the researchers found that before the exoskeleton begins to rupture, the demonic iron beetle can withstand about 150 Newtons of force-at least 39,000 times its body weight.
The researchers estimate that this is more impressive than it sounds: car tires exert a force of about 100 Newtons when the beetle is driving on a dirty surface. The other terrestrial beetles tested by the team couldn’t even stand half the force of the demonic armor.
Zavattieri’s laboratory followed these experiments through extensive computer simulations and 3D printed models that isolated certain structures to better understand their role in saving the lives of beetles.
Taken together, all these studies show that under compression pressure, such as car tires, the jigsaw-like sutures of the demonic iron beetle provide two lines of defense.
First, the interconnected blades are locked to prevent themselves from being pulled out of the suture like puzzle pieces. Second, the sutures and blades are layered, resulting in a more graceful deformation and alleviating the catastrophic failure of the exoskeleton. Each strategy dissipates energy to avoid the deadly impact on the neck of the beetle where the exoskeleton is most ruptured.
Even with the greatest force applied to the beetle’s exoskeleton, layering allows the connected blades to be pulled out more gently from the suture. If the leaves interlock too much or too little, the sudden release of energy can cause the beetle’s neck to break.
It is still unknown whether this demon-like iron beetle can survive the “car accident”. But understanding these strategies can already solve the fatigue problems in various machines.
“A positive engineering challenge is to connect different materials together without limiting their support capabilities. The incredible iron beetle has strategies to circumvent these limitations,” an assistant professor at the University of Texas at San Antonio David Restrepo said that he served as the postdoctoral researcher in the Zavattieri research group.
For example, in the gas turbine of an airplane, metal and composite materials are connected by mechanical fasteners. The fastener adds weight and introduces stresses that can cause cracking and corrosion.
These fasteners will eventually reduce the performance of the system, so they need to be replaced frequently. However, the interface stitching of the demonic iron beetle provides powerful and more predictable failures that can help solve these problems. Hosseini is now an engineering manager for Procter & Gamble.
Researchers at the University of California, Irvine have created a carbon fiber composite fastener that mimics the suture of the vicious iron-clad beetle. Purdue University researchers found through load tests that this type of fastener is as strong as standard aviation fasteners, but much tougher.
“This work shows that we can use fragile dissipated energy to transform it from a strong, brittle material to a strong and tough material. Zavattieri said: “This is what nature enables the demonic iron beetle to do. . ”
The Air Force Research Office and Army Research Office funded this work through a multi-university research program. This research used the resources of the Advanced Light Source at the User Facilities of the US Department of Energy’s Office of Science.

Post time: Nov-02-2020