Looking for "the strongest close fitting armor" ■ Xing Zheliang Shuai, Shang Xiaowei Not long ago, the Russian military revealed that they would distribute a new sotnik combat system for infantry and special forces. It is noteworthy that the new bulletproof vest in this system can effectively defend against large caliber bullets. Since the birth of bulletproof clothing, scientists from various countries have been trying to innovate and upgrade bulletproof clothing materials and processes. Today, more and more new bulletproof vests with strong protection, light weight, good comprehensiveness, comfort and durability have been born one after another, and have become the "standard" for soldiers all over the world. On the Internet, search the keyword "bulletproof clothing" to find new equipment such as liquid bulletproof clothing, spider silk bulletproof clothing and electronic bulletproof clothing. So, how are these advanced bulletproof vests bulletproof? Is it really invulnerable? Where is its "hood door"? This article will answer your questions. A certain type of Russian bulletproof vest. Data photos Weight loss and strong energy, "customized" bulletproof vest A spear makes a shield. In the face of bullets as fast as lightning, bulletproof vests came into being. Bulletproof vest, known as "the strongest close fitting armor". In the early days, bulletproof vests were mostly made of steel plates. Although they could effectively prevent bullet shooting and reduce soldiers' casualties, tens of kilograms of "load" made soldiers miserable. On the battlefield, high-speed rotating bullets hit the armor, which will have a great impact on the internal organs and bones of soldiers. It is difficult for soldiers to complete conventional tactical actions with such heavy bulletproof vests. Data show that soldiers' mobile combat capability will be reduced by more than 30% if they wear 10 kg bulletproof vests. Therefore, scientists from various countries have carried out research on the subject of how to "reduce weight and strengthen energy" of bulletproof vests. The material selection of bulletproof clothing is very important. Scientists try to "lose weight" for bulletproof vests as much as possible while ensuring their protection. In the 1860s, scientists made "cotton back armor" with more than 10 layers of cotton fiber. This soft armor had a good defense effect in actual combat. Since then, American scientist zieglen invented the "Silk bulletproof jacket", which is still sought after by buyers all over the world despite its high price. With the rapid development of science and technology, the U.S. military equipment research department found that manganese steel not only has the advantages of "hard" and "light", but also is cheap. It is an excellent material for manufacturing bulletproof vests. In the 1970s, Kevlar bulletproof vests came out. The strength of this bulletproof clothing material is five times that of steel of the same quality, and the density is only one fifth of that of steel. The test shows that the ability of Kevlar bulletproof vest to absorb the kinetic energy of shrapnel is 1.6 times that of nylon and 2 times that of steel. A Kevlar bulletproof vest weighing 1.8 kg can resist the close range firing of 0.44 mm pistol bullets. Not only lose weight, but also be strong. The Russian reinforced composite high strength material center has developed a bulletproof vest that can "float on the water" and named it "amphibious". The bulletproof vest adds a floating lining plate outside the armor to ensure that fully armed soldiers can float in the water; The British Defense Science and technology laboratory has led the development of a new type of ceramic bulletproof clothing, which further enhances the flexibility of bulletproof clothing and makes soldiers more flexible in tactical actions on the battlefield on the premise of ensuring high-quality protection. In addition, "tailored" makes the personality of bulletproof vests more distinctive. Some countries have designed women's bulletproof vests for women. Compared with men's bulletproof vests, these bulletproof vests are more suitable for women's figure, with good wrapping and strong defense. "Delicate body", bulletproof vests are not invulnerable If you think you have a "Golden Bell Jar" by wearing bulletproof vests, you are very wrong. At present, no bulletproof vests in the world are perfect. They all have their own "cover doors". Bulletproof clothing is not invulnerable. It can only defend against some bullets with smaller caliber. The protective effect is not ideal for grenades with larger caliber, as well as non lethal smoke bombs and flash bombs. On the battlefield, soldiers wearing bulletproof vests may be shot repeatedly. In particular, after the soft bulletproof clothing is hit by the bullet for the first time, the fibers in the corresponding parts will stretch or break, so it can not form an effective defense against continuous bullets. We know that the working principle of bulletproof vest is to absorb bullet kinetic energy through the fragmentation of bulletproof plate. After the bulletproof plate is impacted, it will cause large-area damage to the corresponding parts and affect the protective performance of bulletproof clothing. When the bulletproof vest is continuously fired by bullets, the bulletproof plate usually deviates from the original position, which affects the protective performance of the bulletproof vest to a certain extent. In 2003, a foreign policeman was caught by a bullet while arresting a drug dealer. The bullet penetrated the soft bulletproof vest and penetrated into the abdomen. At that time, the bulletproof vest worn by the policeman was made of 100% Zelong material, which had the advantages of good protection, light weight, comfort and convenience. It is reasonable to say that this bulletproof vest will not be easily broken down, but why does this result happen? After investigation, it was found that the Zelong fiber of the police's bulletproof vest was aging and the protection ability decreased by about 30%. In fact, bulletproof vests are a kind of "delicate" equipment. Both Kevlar and zelon are synthetic chemical fibers, which are prone to natural aging in the process of daily use. On the one hand, in the case of direct sunlight, the aging process of chemical fiber will be greatly accelerated. When the irradiation reaches a certain time, the tensile strength of the material will decrease sharply; On the other hand, the service life of chemical fiber is also related to the ambient temperature, especially after being greatly impacted by the warhead, the local temperature rises sharply and the protective performance decreases sharply. In order to maintain the "combat readiness" of bulletproof vests at all times, it is necessary to replace seriously aged bulletproof vests in time. Users should also regularly maintain bulletproof vests and take protective measures such as moisture-proof and sunscreen. At present, there are many kinds of bulletproof vests in the world, among which the most common is Kevlar bulletproof vests. Although it has a good performance in protecting low-speed bullets and explosive fragments, it is often "weak" in protection when encountering high-speed bullets fired by rifles. Foreign countries usually classify the protective performance of bulletproof clothing. According to the international commonly used NIJ standard, the protective performance of bulletproof clothing is divided into 6 levels from low to high, and each protection level corresponds to different types of caliber bullets. Among them, the bulletproof vest with the highest protection level can resist bullets with a firing speed of 850 m / s, and the protection effect is amazing. Innovative mix and match, the "science and technology model" of liquid bulletproof clothing Do you believe that bulletproof vests can be lighter than paper but harder than diamond? Scientists have done a micro ballistic test: a tiny silicon particle shoots at a single layer of graphene at a speed of 3000 meters / second. Surprisingly, this honeycomb structure material can quickly disperse the impact force of silicon particles, interrupt the abduction wave passing through the material, and has stronger impact resistance than ordinary materials. So far, graphene is the thinnest and strongest material in nature. Its breaking strength is 200 times higher than that of the best steel, and can replace Kevlar, aramid and other materials. Graphene material can not only easily resist bullets, but also greatly reduce the battlefield load of soldiers. Seeing here, you may praise that graphene material is so "tall", but the pace of scientists' innovation has not stopped. Recently, a British company launched a liquid bulletproof vest, which is much stronger than the traditional bulletproof vest, lighter and more flexible. The materials used are fiber and liquid. We know that the liquid is soft and flowing, while the armor is hard and firm. How can these two "little partners" be well combined? This starts with a special liquid—— According to Newton's law of viscosity, the viscosity of liquid is constant. For example, water, alcohol and other liquids are called Newtonian fluids. Then, a non-Newtonian fluid is a liquid that does not satisfy Newton's law of viscosity, and its viscosity is a variable. This reflects the important characteristics of non-Newtonian fluid: the viscosity of fluid will increase with the increase of pressure and impact force. When designing and manufacturing bulletproof vests, the company innovatively uses a liquid called "shear thickener", in which many special particles are freely suspended. When the bullet hits this material at high speed, the particles in the "shear thickener" will absorb the impact energy and quickly become extremely hard, thus blocking the bullet. When used with Kevlar fiber, this liquid can produce the effect of "1 + 1 > 2". In order to meet the needs of future battlefield, scientists also organically combine various new bulletproof vests with individual modular equipment. Their common practice is to design modular interfaces on bulletproof vests, which can place individual weapons such as bullet bags and grenade bags. Some are also ingeniously equipped with gripping strips at the back to ensure that soldiers can be dragged to safety by their comrades in arms in time after being injured or losing their ability to move. I believe that taking advantage of the "east wind of science and technology", bulletproof vests will move towards the goal of "harder, lighter and stronger" in the future, and become a real soldier "amulet". (outlook new era)