Sep 15, 2017 | By Julia

A team of mechanical engineers at McGill University in Montreal are drawing inspiration from the animal kingdom in their development of new 3D printed armours. At first glance, conch shells, fish scales, and spider silk have little to do with bullet-proof vests, sports helmets, and protective gloves. But according to McGill engineer Francois Barthelat, there’s more than meets the eye in these natural structures.


“Nature has been playing this game for millions and millions of years,” Barthelat told Popsci. Whether in the form of shells, scales or silk, animals’ natural “shields” are essential for withstanding pounding winds and waves, or predators’ razor sharp teeth and claws. “It’s really a very large reservoir of inspiration,” he notes. Now, Barthelat is tapping into that reservoir in exploring new frameworks for manufacturing human armour. As the mechanical engineer notes, the possibilities are vast.

Take the alligator gar, for instance. The ray-finned euryhaline fish native to Louisiana and Texas waters sports nearly impenetrable scales. As a form of natural armour that’s much tougher than most fish scales, the gar scales are so tough that even a knife can’t slice through them. “It’s very bony and it almost feels like teeth,” Barthelat says.



The team’s testing began with dead fish from the market and a simple needle. The McGill engineers initially began experimenting on the striped bass, a common fish with relatively sturdy scales that nevertheless were punctured immediately by needlepoint. Yet “when we did the same tests on the garfish,” Barthelat notes, “we just couldn’t go through the skin. The little needle would basically buckle and break.” Even a larger steel needle was unable to fracture the garfish’s scales.

Duly impressed, Barthelat and his colleagues set to work mimicking the heavy skin of the gar. The team has so far been focused on perfecting the intricate arrangement of the scales: they’re 3D printing plastic scales onto rubber pads, then tweaking the size, spacing, shape, and thickness to see which versions perform best.

After experimenting with several different arrangements, the engineering team found that the strongest armours were those closest to real gar scales. It turns out that the smaller the scale, the harder it is to break. Scales that overlap, similar to real fish scales, also display considerable strength by better distributing force.

Barthelat and his colleagues have now moved on to producing ceramic scales which are then glued onto Kevlar gloves, intended for handling sharp objects. Yet Kevlar gloves don’t make the wearer invincible: even though the gloves are nearly impossible to slice through with a knife, a needle can easily slide through the threads of the Kevlar fabric. That means danger for workers who clean up parks or sort recycling, as even an overlooked needle could still do considerable damage. As Barthelat explains, “The best that technology has to offer now is something that does not protect them adequately for the type of work they’re doing.”



Next up Barthelat will be tackling the material itself. His goal is ultimately to manufacture gloves that can protect the wearer from punctures, while remaining pliant enough to allow adequate movement. Current prototypes in the works are studded with laser-cut aluminum oxide scales measuring 2 millimetres in size, although Barthelat reckons even smaller scales would be useful for areas around the finger joints. Ontario-based company Superior Glove has performed extensive testing with positive results; Barthelat says the gloves held up against standard tests.

While the gar-inspired scales are working well on protective gloves, Barthelat acknowledges that armour such as bulletproof vests are a different story. Even so, the engineer-designed scales could help protect against stab wounds, or could be used to supplement the vulnerable areas of more standard armour. “If we can solve the issue of bio-inspired design for gloves and the fingers, then we can pretty much handle anything on the body,” he says.

 

 

Posted in 3D Printing Application

 

 

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