How the diabolical ironclad beetle is virtually 'uncrushable'

ByAmy Woodyatt, CNN, CNNWire
Thursday, October 22, 2020
How the diabolical ironclad beetle is virtually 'uncrushable'
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Scientists developing new materials are studying an unlikely source of strength: a beetle that can withstand being run over by a car.

Scientists developing new materials are studying an unlikely source of strength: a beetle that can withstand being run over by a car.

Researchers from Purdue University and the University of California, Irvine, studied the aptly named diabolical ironclad beetle -- Phloeodes diabolicus -- to understand the secret behind its strength.

"If you take any beetle, and you want to collapse it with your finger, you can probably kill it," he told CNN.

But not the diabolical ironclad beetle. "This beetle is so tough that the energy or the force that you can do with your hand, it's not enough -- it's like a piece of rock," Pablo D. Zavattieri, a professor of civil engineering at Purdue and a study author, told CNN. "The tire of a car is not enough to collapse it."

The findings were published in the journal Nature on Wednesday.

Experts wanted to understand why, in the hopes of re-creating such strength in construction materials.

Using advanced microscopy, spectroscopy and in situ mechanical testing, researchers identified the architectural designs within the creature's exoskeleton.

The scientists discovered that the diabolical ironclad beetle's super-toughness lies in its armor. The insect has two armorlike "elytron"-- used in flying beetles to deploy wings -- that meet at a line, called a suture, running the length of its abdomen.

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Millions of years ago, most beetles flew, Zavattieri explained. "This particular beetle, as part of the evolution process, it doesn't fly any more," he said.

Though the diabolical ironclad beetle doesn't use its elyton for flight, the elytra and connective suture instead help to distribute applied force more evenly throughout the insect's body.

Zavattieri explained that the suture acts like a jigsaw puzzle, connecting the creature's various exoskeletal blades in the abdomen, which lock to prevent themselves from pulling out.

If the suture is broken, another protective mechanism also allows for the blades to deform slowly. That prevents a sudden release of energy, which would otherwise snap the beetle's neck.

Using steel plates, the team of researchers discovered that the creature can take an applied force of 150 newtons -- some 39,000 times its body weight -- before its exoskeleton starts to fracture.

A car tire would apply force of around 100 newtons if driving over the insect on a dirt surface, scientists said.

The team hopes that in better understanding how the beetle withstands such force, they can develop tougher materials.

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One of the critical problems in engineering is connecting materials of different compositions, for example, connecting aluminum and steel, in fields like aerospace, Zavattieri told CNN.

For example, when building aircraft turbines, metals are often joined to composite materials with mechanical fasteners, which can add weight, introduce stress and ultimately lead to features and corrosion in the structure.

"We have the materials. One of the engineering issues is how to connect them," Zavattieri said.

"We can use these sutures -- they are showing you the way the beetle does it -- to improve the toughness of these," he said.

"This is a good example of how nature uses this connection," he said. "Every single time we look at nature, we learn something new."