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Indigenous Technology Of Soft Body Armour For Defence Applications Using 3d Woven Aramid Fabrics
Project Description :

Soft body armours are developed by using multiple layers of high performance fabrics. generally 30-40 layers of 2d fabrics woven aramid fabrics (kevlar, technora etc.) or ultrahigh molecular weight polyethylene (uhmwpe) sheets are assembled together to make soft armour panel which becomes heavy and inflexible. in this innovation, two approaches have been amalgamated to reduce the weight of body armour and improve their effectiveness against bullets fired from pistol and revolver (velocity up to 450 m/s). the 2d fabrics have been replaced with 3d fabrics in which yarns are arranged in three perpendicular directions, namely x, y and z. 3d fabrics have reinforcing yarns in three directions making the structure coherent and more effective in impact energy dissipation. 3d fabrics were then treated with shear thickening fluid (stf). viscosity of stf increases drastically when the shear rate crosses a critical level and thus stf behaves like a solid material thereby facilitating impact energy absorption. stf treated 3d fabric prototypes have been developed in this research. the prototypes developed have been tested against projectile fired from 0.38 inch calibre revolver (165 m/s) and 9 x 19 mm bullets (450 m/s). the results were optimistic as two layer of stf treated 3d fabric structure were able to stop bullets of 165 m/s. soft armour panel having stf treated 3d fabrics stopped bullets fired at 450 m/s. the innovation has also shown the importance of structural optimization of 3d fabric for ballistic applications. the ratio of yarns in y (stuffer) and z (binder) directions were varied at three levels (3:2, 3:1 and 4:1) keeping total number of yarns same (800 yarns of 720 denier). the areal density of all the 3d fabrics were around 520-550 g/m square. stf were developed in the laboratory by dispensing silica particles (100 nm) in peg (mw 200) using ultrasonicator. solid content in stf was (65% w/w). the developed 3d fabrics were treated with stf using padding mangle using optimized nip pressure. for 3d fabrics, increase in the ratio of stuffer to binder yarns increased the impact energy absorption. the highest impact energy was absorbed when the ratio of stuffer to binder yarns was 4:1, though most of the bullets pierced the fabrics even when two layers of 3d fabrics were used. after the stf treatment, impact energy absorption increased for single as well as double layer 3d fabrics. only the stf treated double layer 3d woven fabrics having stuffer to binder yarn ratio of 4:1 were able to stop all the bullets (165 m/s). this implies that synergistic role of fabric structure and stf is crucial for ballistic resistance. for high velocity ballistic evaluation (450 m/s) and bfs measurement, eight layers of kevlar xps were used as the sacrificial layers and 3d woven fabrics were used at the back side of panel. fabric panels consisting of stf treated 3d fabrics having stuffer to binder ratio of 3:1 or 4:1 were able to stop all the bullets (six out of six). moreover, the depth of back face signature for these fabrics was varying from 31 to 39 mm which is within the acceptable limit (44 mm). the panel containing stf treated 3d fabric showed dome formation, crack generation and fibre breakage to a lesser extent as compared to those of fabric panels containing untreated 3d fabrics.

 
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Project Details :
  • Date : Dec 30,2016
  • Innovator : Animesh Laha
  • Guide Name : Prof. Abhijit Majumdar
  • College :
  • Submission Year : 2017
  • Category : Textile
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