Investgation Of Fabrication Of Aramid Fiber Flexible Composite And Its Stab Resistance

Since the 911 terrorism attack, the anti-terrorism has become a global issue. Stab-resistant armor is a protective clothe prepared for people who work in dangerous environments and easily suffer from assaults, such as police officers, and soldiers. The stab-resistant armors are main equipment for soldiers and police officers especially in gun-control countries. Thus the development of stab-resistant body armor, especially soft and light body armor, is urgent and very important.First, based on the requirement of stab-resistant material, the raw materials were selected and the structures of aramid fiber reinforced composites were designed. Different resin matrixes were studied so that the best resin was selected. And then different processing methods were investigated and the mould-press processing was used. The whole process included cutting, pre-treatment, laminate, pre-warm, hot-press and demoulding. The effects of temperature, pressure, processing time and thickness of surlyn film on the composite laminate performance were studied. In the range of 100℃and 170℃, the higher the temperature, the better is the performance of the composites. The higher the pressure, the better is their static performance. When the temperature and pressure were increased to higher value, the resin would be adhered to PTFE(polytetrafluoroethylene) , indicating the surface of the composites was damaged. Meanwhile, the processing time exhibited little effect on the performance of the composites.Aramid fiber reinforced composites were fabricated with the optimized parameters, and the influence of composite structures on its performance was studied. First, the influence of the thickness of resin on the composite properties was examined. When the resin film is 80?m thick, the best performance of composite materials can be achieved. In addition, based on the experimental results, the 1K2S structure (top and bottom layer is surlyn film, the middle layer is aramid fabrics) was identified as the best optimized structure. Based on the preceding studies, the stab-resistant structure was designed and developed through the analysis of stab-resistant processes. The aramid fiber fabrics and aramid fiber reinforced composites were selected as the basic materials, and they were constructed into 3 kinds of stab-resistant structures with the same density and number of layers. The double-layer structure consisted of aramid fabrics layer and composites layer. The sandwich structure consisted of a composites layer between two aramid fabrics layers or an aramid fabrics layer between two composites layers. The mixed structure consisted of two aramid fabrics layers and two composites layers in which several layers were mixed together. The stab resistance tests showed that the sandwich structure reached the GA68-2008 stab resistance standard, while the other two structures did not. Therefore, the sandwich structure was selected.The fracture surfaces of composite targets with different structures were examined using scanning electron microscopy. the composites and aramid fabrics presented different fracture surface morphologies. The fracture of aramid reinforced composites usually exhibited a shearing failure characteristic, while the fracture of aramid fabrics usually presented a tensile failure characteristic. Through the analysis of stab-resistant processes, the stab-resistant mechanisms of composites and stab-resistant structures were explored, and the stab-resistant models of different structures were established.