Wars and conflicts in human history have led to the continuous development of weapons, and the development of science and technology has made the progress of weapon research and development faster and more lethal. In various periods of history, the renewal of weapons and the advancement of protective materials basically appeared simultaneously. For example, there are records of spears and shields in Chinese history. In the era of cold weapons, personal protective materials used include leather, fabrics and their mixtures, chain mail, metal plates, etc. The emergence of thermal weapons has brought the selection and use of protective materials to a new level. During the First World War, the British army invented a scaly flexible bulletproof suit made of metal sheets, while the German army used a shoulder metal plate as a rigid body armor; the latter was too heavy, and the German body armor was mainly made of unnecessary Used by machine gunners who exercise frequently. The U.S. military made the earliest bulletproof vests by sewing laminated steel plates into thick fabrics between 1920 and 1930. However, due to the heavy and expensive weight and the need to frequently replace the steel plates deformed after bullet strikes, there are few users[2 ]. Polyamide synthetic fiber (nylon) came out in 1938 and was subsequently used to make soft body armor, which was widely used during World War II and the subsequent Korean War. In 1950, the production of nylon for bullet-proof was started, and it was widely used in the development and production of flexible bullet-proof materials. Nylon soft body armor has a strong defense against explosive fragments, but it cannot achieve effective protection against bullets due to its low strength. In 1965, DuPont's aramid 'Kevlar?' came out. Its strength is 1.6 times higher than that of bulletproof nylon, its tensile modulus is 21 times higher, and its elongation at break is one-fifth of that of bulletproof nylon. One , has revolutionary significance for the development of high-efficiency bulletproof materials. The current bulletproof materials are divided into soft and hard. Soft materials are made of high-performance fibers through textile technology, and hard materials refer to ceramic inserts, composite inserts and metal inserts. In low-risk situations, soft body armor is generally used; in high-risk situations, such as battlefields, body armor users will use two types of bulletproof materials at the same time. Compared with previous bulletproof materials, contemporary bulletproof materials are already lightweight and efficient, but the bulletproof effect, quality, and thickness of bulletproof vests have always been important goals for continuous improvement and improvement. At present, a complete set of personal bulletproof equipment can still weigh up to 14-17 kg. Such a mass will still greatly limit the movement flexibility of body armor users. Weapons are constantly improving and updating, which also puts forward higher requirements for the protective performance of bulletproof materials. Therefore, due to the diversification of dangers, in addition to bulletproof, it is also required that the body armor provide sufficient puncture resistance. Starting from the improvement of fiber strength utilization and the development of high performance and light weight, this paper discusses the influence of the friction performance between yarns and structural design on the anti-stab performance of materials, in order to provide new ideas for the research of ballistic materials. 1 Test standard for bulletproof materials The bulletproof capability design of body armor is based on the hazard level of the environment in which it is used. Celebrity politicians, security personnel, riot police and combat soldiers are all users of body armor, but they face significantly different levels of danger. The National Institute of Justice (NIJ) was the first institution to formulate standards for protective equipment. The standards cover body armor, bulletproof helmets, puncture-resistant body armor, and other bulletproof materials. NIJ 0101.06 'Ballistic Performance of Bulletproof Clothing' is the test
ing standard for body armor developed by NIJ , which divides bulletproof materials into 5 types according to the degree of damage, namely IIA, II, IIIA, III, IV levels and special types. In order to make the test results comparable, the types of bullets used, the quality of the bullets and the speed of the bullets are specified for different levels of bulletproof materials. For example, the type of bullet that needs to be used in the test of IIIA bulletproof material is 0.357 SIG all-metal shell flat-head warhead, with a warhead mass of 8.1 g, and the bullet speed of the new body armor tested is (448±9.1) m/s. Reaching the bulletproof material means meeting two indicators: one is that the bullet is blocked by the bulletproof material; the other is that the back deformation of the bulletproof material is less than 44 mm. The testing standards for bulletproof materials in other countries basically follow the principles of the US NIJ. The 2017 edition of the bulletproof vest standard formulated by the Science and Development Agency of the Ministry of the Interior  divides the bulletproof grades into HO1, HO2, HO3, HO4 and SG1. The bullet type of HO2 bulletproof grade material is 9 mm full metal shell bullet or carapace hollow bullet, the bullet mass is 8.0 g, and the test speed is (430±10) m/s.
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