Preparation And Properties Study Of Kevlar129Fabric/PA Bulletproof Composite

The application of thermoplastic resin matrix bulletproof composites becomes wider in the bulletproof field due to its good toughness, high impact damage tolerance, environment friendly etc. Numerical method has been an important method of studying their impact mechanisms. Although there are a lot of researches for the fabric finite element simulations, most of them focus on the macrostructure, these traditional macroscopic models cannot explain the interaction between yarns, such as yarn structures, properties and friction between the yarns, etc. In this paper, Kevlar129/PA(polyamide) composite material is the main object of study, the research method used is the combination between experiment and finite element simulation, the systematic research has been carried out around the composite forming process, mechanical properties, anti-ballistic penetration performance and failure mechanism of the composites.In the research of composite molding process, the orthogonal experiments of the composite process influence factors which include molding temperature, molding pressure, molding time are carried out. The influence of the three factors on tensile performance, stripping performance and ballistic impact performance has been discussed. The results show that the better molding process conditions are molding pressure7.5MPa, molding temperature115℃, molding time20min. The biggest effect factor of the mentioned above is the molding pressure. When the molding pressure is7.5MPa, the ballistic impact performance reaches the maximum value, energy absorption and composite tensile properties and stripping performance are consistent.Based on the tensile mechanical property test of the Kevlar129yarn and the finite element model which can reflect yarn crimp and established finite element analysis model of the fabric and the composite in the level of yarn structure, the elastic orthotropic material model with principal stress failure criterion was used to compare and analyze tensile mechanical properties of the fabric, the finite element analysis method of predicting tensile mechanical properties of fabric was obtained, and the yarn and fabric tensile fracture process was analyzed. Comparing the finite element analysis with experimental results of Kevlar fabric tensile properties, it is concluded that the initial stage of tensile stress is lower, the tensile stress before tension failure is a little higher, the overall degree of agreement is good, and the prediction of the mechanical property near the breaking point still needs to be further improved. Through the simulation of fabric peeling performance, the adhesive force between the yarn and the resin is determined. At the same time the tensile properties of the composites were studied, and the result shows that the tensile fracture of the composite is simultaneous, the fracture is brittle.Based on the composite structure, the finite element analysis model of the fabric is established in the yarn structure level. Ballistic impact process is simulated through the finite element analysis software ANSYS/LS-DYNA, the residual velocity of the projectile; residual energy and the damage failure process of target plate have been obtained. The friction coefficient between the yarns and influence of the adhesive force between the fabric and resin on energy absorption are also studied. The target plate ballistic penetration process, further, the target plate ballistic penetration failure mechanism are analyzed from the calculation results of the target plate deformation, stress wave transmission process, the projectile velocity, acceleration change process and the energy change process.