The liquid is called Shear-Thickening Fluid (STF). STF does not
conform to the model of Newtonian liquids, such as water, in which
the force required to move the fluid faster must increase
exponentially, and its resistance to flow changes according to
temperature. Instead STF hardens upon impact at any temperature,
providing protection from penetration by high-speed projectiles and
additionally dispersing energy over a larger area.
"This viscosity increases thanks to the subordination of the
particles in the liquid structure, therefore they form a barrier
against an external penetrating factor," said Karolina Olszewska,
who performed tests on the STF for Moratex.
The exact composition of the STF is known only to Moratex and its
inventors at the Military Institute of Armament Technology in
Warsaw, but ballistic tests proved its resistance to a wide range of
projectiles.
"We needed to find, design a liquid that functions both with
projectiles hitting at the velocity of 450 meters per second and
higher. We have succeeded," said Deputy Director for Research at the
Moratex institute, Marcin Struszczyk.
Struszczyk said the liquid's stopping capability, combined with the
lower indentation of its surface, provides a higher safety level for
the user compared with traditional, mostly Kevlar-based, solutions.
"If a protective vest is fitted to the body, then a four centimeter
deep deflection may cause injury to the sternum, sternum fracture,
myocardial infarction, lethal damage to the spleen," Struszczyk
said.
"Thanks to the properties of the liquid, thanks to the proper
formation of the insert, we eliminate one hundred percent of this
threat because we have reduced the deflection from four centimeters
to one centimeter."
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When hit by a high-speed projectile, a wide area of the STF hardens
instantly, causing the usually massive energy to be dispersed away
from the wearer's internal organs.
Implementing the solution in body armor required designing special
inserts, but the company says those are lighter than standard
ballistic inserts and broader range of movement for their users in
the police and military.
"The point is for them not to interfere, not change the way of
movement, operation of such the product by the user, and at the same
time increase their motor skills, increase effectiveness of their
decision process and increase their possibilities during the mission
at hand," Struszczyk said.
The laboratory is also working on a magnetorheological fluid, which
they hope can be also applied in their products.
According to the researchers, both liquids can find applications
beyond body armor, such as in the production of professional sports
inserts, and even entire outfits. Another use could be in car
bumpers or road protective barriers.
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