AIRCRAFT COULD BE STRONGER THANKS TO A BEETLE

In future, Aircraft could be designed and manufactured super-tough thanks to the ironclad beetle.

The ironclad beetle features exoskeletal blades that join together like puzzle pieces.

The ironclad beetle can be run over by a car, and still survive. This fascinating bit of nature has got engineers thinking, and could pave the way for a new breed of materials that bear similar characteristics. The toughness of this beetle is down to a few secrets.

Engineers at Purdue University carried out the research and the team has uncovered new detail around how the creature absorbs such tremendous impacts, focused on the incredibly tough exoskeleton of this arthropod.

Using compressive steel plates and CT scans, the team observed the ironclad’s exoskeleton at work under increasing pressures, finding that it can handle loads at least 39,000 times its own body weight before fracturing – that’s equal to an applied force of around 150 newtons.

The Pardue team used computer simulations and 3D-printed models to isolate the detailed structures within the exoskeleton, which highlighted the role of a connective suture that runs the length of the beetle’s abdomen.

The structure that makes the ironclad beetle strong has been copied by engineers.

This suture lies between the two wing cases of the beetle, called the elytra. The suture connects the elytra and exoskeleton blades beneath them, helping distribute force evenly across the beetle’s body via two intricate mechanisms.

The blades of the exoskeleton lock themselves into one another like pieces of a jigsaw puzzle, which prevents them being yanked out of place under great force, while, the suture and the blades divide into layers.

Both of these mechanisms together work to spread the load across the beetle and avoid fatal fractures at its neck.

One of the areas the team hopes to apply this knowledge to is in the gas turbines of aircraft, where metals and composite materials need to be combined using heavy mechanical fasteners that can cause fracturing and stress over time.

The engineers created a carbon fiber composite fastener based on the ironclad’s exoskeleton structure and carried out loading tests, finding it to be just as strong and significantly tougher than aerospace fasteners used today.

“This work shows that we may be able to shift from using strong, brittle materials to ones that can be both strong and tough by dissipating energy as they break,” says study author Pablo Zavattieri. “That’s what nature has enabled the diabolical ironclad beetle to do.”

(The study was published in the journal Nature.)

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