| With the development of technology, people’s requirement of protective equipment is no longer limited to excellent protection performance, and they also pursue the light quality and softness. It is one of the important topics on armor protection field how to design the light equipment with high performance. Fiber composites have broad application prospects in this field. High performance fibers always exist in the woven fabric and the UD cloth. There are many factors that can influence the bulletproof performance of fabrics such as fiber materials, organization structure, thickness, combination and so on.In this research, preparation and composite technology of STF was optimized on the basis of preliminary study. Kevlar fibers and ultra-high molecular weight polyethylene fibers as raw materials were used. Kevlar plain woven fabrics, UD clothes and other fabrics made by the research group were designed to make multi-layered textiles. 21 kinds of combinations were designed from the plane direction, and 46 kinds of combinations were designed from the thickness direction, such as changing the ply location, the angle and the structure of fabrics. The bulletproof performances of the samples were assessed by ballistic impact tests. Moreover, the effect of the combination on the bulletproof performance was also discussed and seeked out the best one.The following conclusions can be drawn.(1) In order to secure uniform mixture effect of the STF dispersed system, preparation technology of STF was optimized by using electric mixer and ultrasonic vibration, and the temperature was controlled on 25℃. Composite technology of STF was also optimized. In addition to the composite technology of dry STF, sealing process by UD clothes was used to make the STF present in the fabric by liquid. High performance fibers and fabrics were compound with four kinds of solid content of SiO2. With the increasing of solid content of SiO2, the basic performances of fibers and fabrics are improved effectively.(2) The Kevlar wrapped yarns and polypropylene wrapped yarns were used to make 9 kinds of plain weave fabrics, and one type of composite technology was choosed to make STF-Kevlar/PE fabrics. And gram weight of fabrics increases about 35%. As the fabric of polypropylene spacing decreases, better permeability is got by the fabrics.With the increase in number of fabric layers, permeability is falling. Moreover, in the 4-layers textile, interweave resistance of the outer fabrics is weaker and interweave resistance of two fabrics in the middle is better. Then, 8 kinds of combined woven structures were designed, and the woves were made by UHMWPE fibers. It has been found that the tightness of quasi orthogonal structure unit is higher than orthogonal structure unit, and the fabrics of combined structures give better softness.(3) For the 4-layered textile with combinations designed from the plane direction such as changing the ply location and the angle of fabrics, placing the plain weave fabric close to the impact face exhibited better bulletproof performance and larger area of bullet hole. It had also been found that when the ply angle is 0°/75°/150°/225°, the fabrics between each layer got the most obvious anisotropy, and BPI value upon ballistic impact was higher. Moreover, the results show that orthogonal structure unit exhibits better shear resistance and is for the impact face. Placing orthogonal structure unit close to the impact face is 35.7% higher than the quasi orthogonal structure unit of energy absorbed upon ballistic impact. But the quasi orthogonal structure unit gives better tensile resistance.(4) The results showed that the impact speed is increased when round bullets are changed to pointed bullets, and the amount of energy absorbed by the textile in a unit area is reduced, and more broken fabrics are found by shearing action. It has also been found that when the multi-layered textiles are made thicker and similar impact speeds are applied, the more amount of energy is absorbed. In addition, it is also exhibited that Kevlar 30-layers textile is graded to level 2 in the police body armor protection grade and UHMWPE 50-layers textile is graded to level 3.(5) For a centimeter-thick textile with combinations designed from the thickness direction, when the ply angle of textile is 15°, the anisotropy of fabrics is most obvious between each layer. As changing the combinations of fabrics, the larger the proportion of the thickness of UD clothes is designed in the compound fabric, the better the bulletproof performance. And exchanging the position of two kinds of fabrics, the UD fabric comes to be the first layer against bullet, the more energy is absorbed. When the interval of Kevlar plain woven fabrics and UD clothes is 2 layers, the way of energy transfer is changing in warp and weft direction so that the largest impact energy is dissipated by the compound textile. In five fabrics with the same thickness and different structures, the strength of fabrics made by UHMWPE is better than that made by Kevlar, and the Kevlar 3D fabric with the structure of AAABB gets the best ability of impact resistance. |
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