Structure of bulletproof fabric

Structure of bulletproof fabric
In addition to fiber properties and yarn characteristics, the important factor affecting the bulletproof ability of bulletproof clothing and bulletproof cloth is the fabric structure. The fabric structure types used for software bulletproof clothing include knitted fabric, woven fabric, weft free cloth, needle punched nonwoven felt, etc. Knitted fabrics have high elongation, which is conducive to improving wearing comfort. However, this kind of high elongation for impact resistance will produce great l penetrating damage. In addition, due to the anisotropic characteristics of knitted fabrics, they have different degrees of impact resistance in different directions. Therefore, although knitted fabrics have advantages in production cost and production efficiency, they are generally only suitable for the manufacture of stab proof gloves and fencing suits, but not completely used in bulletproof vests. At present, the bulletproof materials widely used in bulletproof clothing are woven fabric, weft free cloth and needle punched nonwoven felt. Due to their different structures, these three kinds of fabrics have different bulletproof mechanisms, which can not be fully explained by ballistics at present. Generally speaking, after the bullet hits the fabric, it will produce a radial vibration wave in the impact point area and diffuse through the yarn at high speed.

When the vibration wave reaches the weaving point of the yarn, one part of the wave will be transmitted to the other side of the weaving point along the original yarn, the other part will be transferred to the interior of the interwoven yarn, and another part will be reflected back along the original yarn to form a reflected wave. Among the above three fabrics, woven fabrics have many weaving points. After being hit by bullets, the kinetic energy of bullets can be transmitted through the interaction of yarns at the weaving points, so that the impact force of bullets or shrapnel can be absorbed in a large area. But at the same time, the interleaving point plays a role of fixed end. The reflected wave formed at the fixed end will produce Sanga in the same direction as the original incident wave, which greatly enhances the tensile effect of the yarn and breaks after exceeding its breaking strength. In addition, some small shrapnel may push away a single yarn in the woven fabric, thus reducing the penetration resistance of shrapnel. In a certain range, increasing the fabric density can reduce the possibility of the above situation and improve the strength of woven fabrics, but it will enhance the negative effect of stress wave reflection Sanga. Theoretically, unidirectional materials without interlacing points are used to obtain better impact resistance.