As an important personal protective equipment, Bulletproof vest has experienced a transition from metal armor shields to nonmetallic composites, and from simple synthetic materials to synthetic materials and metal armor plates, ceramic panels and other complex system development process. The prototype of the human armor can be traced back to ancient times, the original nation to prevent the body was hurt, had a natural fiber braid as a chest care material. The development of weapons forcing the human armor must have the corresponding progress. As early as the late 19th century, silk used in medieval armor in Japan was also used in American-made Bulletproof vest.
In 1901, after President William McKenley was assassinated, Bulletproof vest caused the attention of the US Congress. Although this Bulletproof vest can prevent low-speed pistol bullets (speed of 122 m / s), but can not prevent rifle bullets. Thus, in the First World War, there have been natural fiber fabric for the clothing lining, together with the steel made of body armor. Thick silk clothing was once the main component of body armor. However, the silk in the trenches metamorphic faster, this defect with limited bulletproof capacity and the high cost of silk, so that the first time in the World War I suffered by the US Ordnance Department of the cold, not universal.
In the Second World War, shrapnel lethality increased by 80%, while 70% of the wounded died due to the trunk injury. The participating countries, especially Britain and the United States began to spare no effort to develop body armor. In 1942 October, the British first developed by the three high manganese steel plate composed of bulletproof vest. In 1943, the United States trial and formal use of body armor there are as many as 23 species. This period of body armor to special steel as the main bulletproof material. In June 1945, the US military successfully developed aluminum alloy and high-strength nylon combination of bulletproof vest, model M12 infantry Bulletproof vest. The nylon 66 (scientific name polyamide 66 fiber) was a synthetic fiber which was found at the time, and its breaking strength (gf / d: gram / denier) was 5.9 to 9.5, and the initial modulus (gf / d) was 21 to 58 , The specific gravity of 1.14 g / (cm) 3, its strength is almost twice the cotton fiber. In the Korean War, the US Army was equipped with a T52 full Nylon body armor made of 12-layer bulletproof nylon, while the Marine Corps was equipped with the M1951 hard "multi-long" FRP bulletproof vest with a weight of 2.7 to 3.6 kg between. Nylon as the raw material of the body armor can provide a certain degree of protection for the soldiers, but the larger, the weight is also up to 6 kg.
In the early 1970s, a high-strength, ultra-high modulus, high temperature synthetic fiber - Kevlar (Kevlar) by the United States DuPont (DuPont) developed, and soon in the field of bulletproof has been applied. The emergence of this high-performance fiber makes the soft fabric bullet-proof clothing performance greatly improved, but also to a large extent to improve the flexibility of Bulletproof vest. US military took the lead in the use of Kevlar production of body armor, and developed the weight of the two models. The new body armor to Kevlar fiber fabric as the main material to bulletproof nylon cloth for the envelope. One light body armor consists of six layers of Kevlar fabric, medium weight of 3.83 kg. With the commercialization of Kevlar, Kevlar's excellent comprehensive performance has made it widely available in military armor. The success of Kevlar and the subsequent emergence of Twaron, Spectra and its use in body armor have led to the increasing prevalence of software bullet-proof vests characterized by high-performance textile fibers, whose scope is not limited to Military sector, and gradually extended to the police and political circles.
However, for high-speed bullets, especially rifles fired bullets, purely soft body armor is still incompetent. To this end, people have developed a soft and hard composite body armor, fiber composite materials as a reinforced panel or board, in order to improve the overall body armor bulletproof capability. In summary, the development of modern body armor has emerged three generations: the first generation of hardware bullet-proof vests, mainly with special steel, aluminum and other metal for bullet-proof materials. This type of body armor is characterized by: clothing heavy, usually about 20 kg, wearing uncomfortable, large restrictions on human activities, with a certain degree of bulletproof performance, but easy to produce secondary fragments.
The second generation of body armor for the software body armor, usually by the multi-layer Kevlar and other high-performance fabric made of fiber. Its light weight, usually only 2 to 3 kg, and the texture is more soft, fit is good, wearing is also more comfortable, wearing a better concealment, especially for police and security personnel or political members of the daily wear use. In the bullet-proof capability, the general can prevent 5 meters away from the pistol shot bullets, will not produce secondary shrapnel, but the bullet hit a larger deformation, can cause a certain non-penetrating injury. Also for rifles or machine guns fired bullets, the general thickness of the soft body armor is difficult to resist. The third generation of body armor is a composite body armor. Usually with light ceramic as the outer layer, Kevlar and other high-performance fiber fabric as the inner layer, is the main development direction of body armor.