Devilish iron beetle

The exoskeleton of a nearly non-crushable beetle could inspire hard structures

By Layal Liverpool

The devilish iron beetle has a tough exoskeleton

David Kisailus

The fiendish iron beetle is so tough that engineers are hoping to copy features of its exoskeleton to design stronger, more robust structures.

“You can run these things over with a car and they won't die,” says David Kisailus of the University of California at Irvine. “We took a Toyota like a sedan and drove over them, and they survived. That was a little surprising. "

To study what makes these creatures virtually impossible to crush, Kisailus and his colleagues performed compression tests on the beetle's exoskeleton while analyzing it under a microscope and using CT.

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The researchers discovered ellipsoidal beam-like structures that surround the beetle's exoskeleton and connect with tiny interlocking blades that form joints between the two segments of the beetle's exoskeletal fore wings, exposing the beetle to extreme compression.

Kisailus hopes that understanding the uniquely robust structure of the fiendish beetle will help develop stronger components for building lighter aircraft, resulting in aircraft that use less fuel and emit less carbon dioxide. "You don't have to reinvent the wheel, just find out what nature has done," he says.

As a test, he and his team joined a carbon-based material with a piece of metal to mimic the joint structure of the beetle's exoskeleton. They found that it was roughly twice as sturdy as a standard hinge commonly used to connect similar parts in aircraft construction.

"In technical applications, connections between materials that are often used often break at their thinnest points due to the concentration of stress," says Po-Yu Chen of National Tsing Hua University in Taiwan. The beetle's tiny interlocking blades offer a new way to improve toughness and prevent fractures on these types of joints, he says.

Why this species of beetle developed such a tough exoskeleton in the first place is a mystery. The beetle spends a lot of time squeezing under rocks and into the bark, says Kisailus, and is older than rodents, birds, and lizards. "Maybe it was just exposed to a more dangerous environment than other bugs."

Journal reference: Nature, DOI: 10.1038 / s41586-020-2813-8

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