Fish scales inspire Chinese bulletproof vest resistant to armour-piercing rounds
- Researchers say their lightweight, flexible armour can protect its wearer from armour-piercing incendiary bullets fired from point-blank range
- Scaled body protection was worn in ancient times but modern developers have struggled to make the technology work
A research team in Changsha in central China’s Hunan province said it had developed the world’s first lightweight, flexible body shield to protect soldiers from armour-piercing weapons.
Three rounds of armour-piercing incendiary (API) bullets were fired from point-blank range (up to 15 metres or 50 feet) into the bionic scale armour at nearly three times the speed of sound. None of the shots penetrated the composite materials, according to a paper published in the domestic peer-reviewed journal Acta Materiae Compositae Sinica on January 5.
The 7.62mm API bullet was initially developed to destroy a tank. It could explode inside the target to inflict greater damage. Later, it was used against individuals wearing protective gear.
When the bullet hit the new vest materials, however, it effectively “vaporised” one of the super-hard ceramic scales and lost most of its kinetic energy, disappearing without a trace, according to lead project scientist professor Zhu Deju of the college of civil engineering at Hunan University.
The shots left dents about 20 millimetres (0.8 inch) deep in a rubber wall behind the vest sample, “proving the good protective performance of the gear”, Zhu and his colleagues said in their paper.
Zhu has been working on several classified military projects, according to his university website. He could not be reached for comment.
Scale-type armour was popular in the ancient world, especially in eastern countries such as China and Japan. But its application in the modern military had been plagued by setbacks.
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The latest example was Dragon Skin, a scaled vest made by the now defunct Pinnacle Armour company in the 2000s, which could endure three shots from an AK-47, according to laboratory testing reports.
But just before signing contracts, the US military found that penetration could occur unexpectedly in combat environments. The California-based company folded in 2010 after losing a number of legal battles to the US military.
Some special operation forces and civilian contractors reportedly wore the Dragon Skin in combat for its flexibility and comfort.
But no bulletproof vest can stop an armour-piercing round without having a plate of ceramic or steel, and these plates could only protect a few vital body areas because of their inflexibility.
Zhu’s team said that their new version of scaled armour was inspired by grass carp, a popular item on the Chinese dining table.
The grass carp was native to eastern Asia and is now the world’s most grown fish in aquaculture. The success of the species comes in part from its scales which had unusually high resistance to piercing and bites, allowing the fish to escape more easily from between a predator’s teeth.
A grass carp scale consists of a hard bony layer on the surface and an elastic, strong membrane underneath. These scales are stacked on top of each other at a unique angle, allowing each scale to twist freely and help dissipate the force of impact.
Zhu and his colleagues had analysed the scales of many other animals – including the armadillo and crocodile – but found that none could match the grass carp scale in terms of flexibility and strength.
In 2020, they developed a soft armour that could withstand pistol fire.
But protection against an armour-piercing bullet was much more difficult because it penetrated the shield much faster.
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After many failures, Zhu’s team found that scales made with silicon carbide, a semiconductor base material, performed best.
The shape, thickness and stacking pattern of the scales had to be calculated using powerful computer modelling which allowed unprecedented detail to produce reliable, consistent results, the team said.
According to the team’s experiment, whether a shot was fatal depended on whether a scale could be converted instantly and completely into powder after being hit by the bullet, according to their experiment.
It is not known when the armour will be tested in a live-firing range.
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The researchers found that the depth of dents increased gradually with the number of shots taken. But they did not disclose how many hits were enough to cause sufficient material fatigue to allow it to be pierced.
The Dragon Skin weighed about 2.5kg (5.5 pounds). Zhu’s team has not revealed the weight of their vest and nor have they detailed information about the glue used to adhere the scales to the vest.
In a harsh environment such as in the desert, high temperatures, sweat and constant motion could affect the strength of the glue and loosen the scales.
It was one of the reasons the Dragon Skin failed, according to the US military.
