Development of bulletproof cloth in bulletproof vest

Development of bulletproof vest
As an important personal protective equipment, bulletproof material has experienced the transition from metal armor protective plate to non-metallic synthetic material, and the development process from simple synthetic material to composite system such as synthetic material, metal armor plate and ceramic protective sheet. The rudiment of human body armor can be traced back to ancient times. In order to prevent the body from being hurt, the primitive people used natural fiber woven belt as breast protection material. The development of weapons forces human armor to make corresponding progress. As early as the late 19th century, silk used in medieval armor in Japan was also used in bulletproof vests produced in the United States. After the assassination of the president in 1901, the bulletproof vest attracted the attention of the United States Congress. Although this bulletproof vest can resist low-speed pistol bullets (the bullet speed is 122 M / s), it can not resist rifle bullets. Therefore, in World War I, bulletproof vests made of natural fiber fabric and steel plate appeared. Thick silk clothing was once the main part of bulletproof clothing. However, silk deteriorated rapidly in the trenches. This defect, coupled with the limited capacity of bulletproof cloth and the high cost of silk, made the silk bulletproof clothing ignored by the U.S. Department of ordnance and failed to be popularized in the first World War. In World War II, the lethality of shrapnel increased by 80%, and 70% of the wounded died of trunk injuries. The Warring States, especially Britain and the United States, began to spare no effort to develop bulletproof vests.

In October 1942, the British army first developed a bulletproof vest composed of three high manganese steel plates. In 1943, 23 kinds of bulletproof vests were produced and officially adopted in the United States. Special steel was the main bulletproof material of bulletproof clothing in this period. In June 1945, the U.S. military successfully developed a bulletproof vest composed of aluminum alloy and high-strength nylon. The model is M12 infantry bulletproof vest. Nylon 66 (polyamide 66 fiber) was a synthetic fiber invented not long ago at that time. Its breaking strength (GF / D: gram / denier) was 5.9 ~ 9.5, its initial modulus (GF / D) was 21 ~ 58, and its specific gravity was 1.14 g / (CM) 3. Its strength was almost twice that of cotton fiber. During the Korean War, the US Army was equipped with T52 all nylon bulletproof vests made of 12 layers of bulletproof nylon, while the Marine Corps was equipped with m1951 hard "duolong" FRP bulletproof vests, with a weight of 2.7 ~ 3.6kg. Bulletproof vests made of nylon can provide soldiers with a certain degree of protection, but they are large and weigh up to 6kg. In the early 1970s, Kevlar, a synthetic fiber with ultra-high strength, high modulus and high temperature resistance, was successfully developed by DuPont company of the United States and soon applied in the field of bulletproof.