Non-Newtonian fluid as armor

Protecting the human body from various weapons is an urgent task for many centuries. In ancient times, warriors often used shields only; in the Middle Ages, heavy armor was widespread, the weight of which was often 30-50 kg. Later, when firearms were widely used, the armor quickly began to lose its relevance, but gave a start in life to modern bulletproof vests, which consist of plates capable of extinguishing the energy of a bullet and fend off a blow with cold weapons. At the same time, progress does not stand still, and body armor is constantly being improved. They are becoming more durable, losing weight and becoming more comfortable to wear.

One of the new solutions in the field of body armor can be armor based on non-Newtonian fluid. Thus, liquid can replace Kevlar. The work in this direction today is led by Polish scientists from the Institute of Security Technology Moratex. They decided to find military use of a long-known substance - a non-Newtonian fluid, whose viscosity during flow depends on the velocity gradient. Liquid armor from Polish experts received the designation STF - Shear-Thickening Fluid. It is able to provide protection against the penetrating power of high-speed means of destruction, well dispersing the shock wave over a large area.


Non-Newtonian fluid is an interesting substance, which at times can behave like a solid, and at times like a real fluid. Ordinary fluid can flow and flow, and non-Newtonian fluid can also. On the other hand, ordinary liquid cannot be solid, form and bounce, and non-Newtonian liquid can. Such a substance is interesting in itself. The reason for this behavior of a non-Newtonian fluid is that most often they are created from large polymer molecules. The "adhesion" between such molecules is not very large, but these molecules are able to glide relatively freely relative to each other. The simplest illustrative everyday example of such a liquid is a mixture of starch with a small amount of water. The faster the external impact on the binder macromolecules suspended in a liquid occurs, the higher the viscosity of the liquid will be.



Unlike ordinary liquids, which can change their structure depending on pressure or temperature fluctuations, non-Newtonian liquids are also able to change their viscosity under stressful conditions. Simply put, they can very quickly turn into durable material. This happens with a sufficiently strong impact, which may include falling into the object of a bullet.

Modern Kevlar bulletproof vests are able to hold a bullet well, but if they hit, they bend to a depth of four centimeters, which is certainly better than a bullet wound, but so a person can get a serious injury in the form of a strong injury or fracture. At the same time, due to the special properties of non-Newtonian fluid and carefully calculated design of inserts, the deformation of a bullet-proof vest using this material is reduced to one centimeter completely safe for humans, eliminating the life-threatening threat to all 100%. In addition, non-Newtonian fluid is able to distribute energy evenly over the entire area of ​​the body armor on impact.

So far, Polish scientists are not in a hurry to disclose the exact composition of their fluid, which is used in their bulletproof vest, but at the same time they claim that such a bulletproof vest is able to stop a bullet that flies at speeds up to 450 m / s. That is, we are talking about pistol bullets. For example, the initial speed of a bullet of a widespread PM is 315 m / s, and a TT pistol is 424-455 m / s. At the same time, the initial speed of a bullet of the equally widespread AK-74М is 900 m / s. According to Polish experts, the use of non-Newtonian fluid virtually eliminates the possibility of rebound due to a much more efficient dissipation of the impact energy. This also means that the carrier of such body armor will feel less impact when a bullet hits it. When struck at high speed, the affected area STF hardens instantly, effectively dissipating the impact energy and protecting the internal human organs.

Non-Newtonian fluid as armor


At the same time, “liquid” armor promises to be fairly light, and the body armor made of it is quite comfortable, which does not prevent a person from performing his work, without causing any inconvenience when wearing, he will not hold down movements. According to the Polish developers, their body armor will weigh easier than products from Kevlar. To judge this is still quite difficult, in the public domain there is only a small video that was published on YouTube.

It should be noted that similar developments at different times were conducted in the UK and the USA. But the fluids created in these countries were the strongest in combination with the protection of Kevlar, which made the vests very heavy. However, Moratex claims that the substance they developed can be used to produce body armor that will require a minimum number of inserts from additional materials. Polish scientists do not intend to dwell only on the military side of their development. In addition, they are working on a magnetorheological fluid that can change its viscosity under the influence of a magnetic field. According to them, both of these fluids can be used not only in the production of body armor, but also for the production of automotive bumpers, professional sports equipment and protective road barriers.



Information sources:
http://hitech.newsru.com/article/17apr2015/liquid
http://hi-news.ru/technology/polyaki-ispytali-puleneprobivaemuyu-zhidkost-dlya-bronezhiletov.html
http://www.popmech.ru/weapon/57836-nenyutonovskaya-bronya-na-smenu-kevlaru-prikhodit-zhidkost
Author:
Yuferev Sergey
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