Fri, Oct 23, 2020 page7

• Beetle armor gives clues to airplane improvements

  • AP, NEW YORK
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  It is a beetle that can withstand bird pecks, animal stomps and even being rolled over by a Toyota Camry.

  Now scientists are studying what the bug’s crush-resistant shell could teach them about designing stronger planes and buildings.

  “This beetle is super tough,” said Purdue University civil engineer Pablo Zavattieri, who was among a group of researchers who ran over the insect with a vehicle as part of a new study.

  

  A photograph taken in 2016 provided by the University of California, Irvine, shows a diabolical ironclad beetle.

  Photo: AP

  So, how does the seemingly indestructible insect do it?

  The species — aptly named diabolical ironclad beetle — owes its might to an unusual armor that is layered and pieced together like a jigsaw, according to the study by Zavattieri and his colleagues published in Nature on Wednesday.

  Its design could help inspire more durable structures and vehicles, they said.

  To understand what gives the 3cm-long beetle its strength, researchers first tested how much squishing it could take.

  The species, which can be found in southern California’s woodlands, withstood compression of about 39,000 times its own weight.

  For a 90kg man, that would be like surviving a 3,538 tonne crush.

  Other local beetle species shattered under one-third as much pressure.

  Researchers then used electron microscopes and CT scans to examine the beetle’s exoskeleton and figure out what made it so strong.

  As is often the case for flightless beetles, the species’ elytra — a protective case that normally sheaths wings — was strengthened and toughened.

  Scientists said that the cover also benefited from jigsaw-like bindings and a layered architecture.

  When compressed, they found that the structure fractured slowly instead of snapping all at once.

  “When you pull them apart, it doesn’t break catastrophically, it just deforms a little bit,” Zavattieri said.

  “That’s crucial for the beetle,” Zavattieri added.

  It could also be useful for engineers who design aircraft and other vehicles with a variety of materials such as steel, plastic and plaster.

  Currently, engineers rely on pins, bolts, welding and adhesives to hold everything together, but those techniques can be prone to degrading.

  In the structure of the beetle’s shell, nature offers an “interesting and elegant” alternative, Zavattieri said.

  Because the beetle-inspired design fractures in a gradual and predictable way, cracks could be more reliably inspected for safety, said Chen Po-yu (陳柏宇), an engineer at National Tsing Hua University not involved in the research.

  The beetle study is part of an US$8 million project funded by the US Air Force to explore how the biology of creatures such as mantis shrimp and bighorn sheep could help with the development of impact-resistant materials.

  “We’re trying to go beyond what nature has done,” said study coauthor David Kisailus, a materials scientist and engineer at the University of California, Irvine.

  The research is the latest effort to borrow from the natural world to solve problems, said Brown University evolutionary biologist Colin Donihue, who was not involved in the study.

  Velcro, for example, was inspired by the hook-like structure of plant burrs.

  Artificial adhesives took a page from the super-clingy feet of geckos.

  Donihue said that endless other traits in nature could offer insight.
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