The diabolical ironclad beetle is so tough that engineers are hoping to copy features of its exoskeleton to design stronger and more robust structures.
“You can run these things over with a car and they don’t die,” says David Kisailus at the University of California, Irvine. “We took a Toyota, like a sedan, and drove over them and they survived. That was kind of surprising.”
To investigate what makes these creatures virtually uncrushable, Kisailus and his colleagues performed compression tests on the beetle’s exoskeleton, while analysing it under a microscope and by CT scan.
The researchers discovered ellipsoidal beam-like structures surrounding the beetle’s exoskeleton, which combine with tiny interlocking blades that form joints between the two segments of the beetle’s exoskeletal forewings, enabling the beetle to endure extreme compression.
Kisailus hopes that understanding the diabolical ironclad beetle’s uniquely tough structure will help inform the design of stronger components for use in building lighter aircraft, resulting in planes that consume less fuel and emit less carbon dioxide. “No need to reinvent the wheel, just figure out what nature’s done,” he says.
As a test, he and his team joined together a carbon-based material with a piece of metal, mimicking the joint structure of the beetle’s exoskeleton. They found it was about twice as tough as a standard joint commonly used to connect similar parts when building aircraft.
“In engineering applications, commonly used joints between materials often fracture at their thinnest regions due to stress concentration,” says Po-Yu Chen at National Tsing Hua University in Taiwan. The beetle’s tiny interlocking blades provide a new way to improve toughness and prevent fracturing at these types of joints, he says.
Why this species of beetle evolved such a tough exoskeleton in the first place is a mystery. The beetle spends a lot of its time squeezing under rocks and into bark, says Kisailus, and is predated by rodents, birds and lizards. “Maybe it was just exposed to a more dangerous environment than other beetles.”
Journal reference: Nature, DOI: 10.1038/s41586-020-2813-8
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