STF Preparation,Performance Characterization And Impact Response Characteristics Of Impregnated Fabric

In the 21st century,unilateralism has gradually risen and riots have occurred frequently.Due to the proliferation of firearms in many regions and countries in the world,the damage of firearms to the human body still ranks first.Although there are many protective materials for firearms,the traditional protective materials are hard metal materials,whose characteristics of thickness and rigidity cannot meet the needs of the wearer ’s comfort and flexibility.In recent years,the new composite material formed by the combination of high-performance fiber fabric and STF has become the preferred alternative material for traditional bulletproof clothing.Although the research on bulletproof fiber fabric materials at home and abroad have achieved phased results.However,there is still a lack of theoretical guidance on the dynamic response and energy absorption mechanism of bulletproof fiber fabrics under complex load conditions.Based on this background,this paper takes the rheological properties of STF under impact load as the breakthrough point,introduces the intelligent response material STF and develops STF-Kevlar and STF-UHMWPF composite fiber fabrics.The combination of experiment,theoretical analysis,and numerical simulation is used to analyze the ballistic mechanism of fabrics,which provides the theoretical basis and experimental reference for the preparation of STF,performance characterization and impact resistance of impregnated fiber fabrics.The main work and research results of this paper are as follows :(1)In view of the fact that there are few researches on the rheological properties of STF under impact loading,this paper studies the dynamic rheological properties of STF by preparing STF with different dispersed phase mass fractions and measuring the steadystate rheological properties of STF by rheometer.The prepared STF was used to impregnate Kevlar fabric and UHMWPEF fabric to explore the effect of impregnated STF treatment on the mechanical properties of the fabric.(2)The impact STF experiments of steel bar free fall and modified SHPB are carried out.The results show that the energy absorption of STF under impact load can be divided into three stages: intrusion stage,equilibrium stage and recovery stage.The equilibrium phase lasts about 3 ～ 4 ms.SHPB impact STF experiment shows that the first response time of STF is 20 ～ 25μs,and the wave velocity of STF is about 592.49 m / s.(3)The monofilament tensile test,monofilament pull-out test,fabric tensile test and steel bullet impact impregnated fiber fabric test was carried out.The results showed that when the fiber fabric was impregnated with STF,the monofilament pull-out load of Kevlar fabric changed from 1394 N to 2790 N,and the energy consumption changed from4.69 J to 7.69 J.The monofilament pull-out load of UHMWPEF fabric changed from2450 N to 3246 N,and the energy consumption changed from 7.91 J to 14.42 J.The steel projectile was loaded by a light gas gun to impact the STF-fabric.The absorption kinetic energy of Kevlar single-layer fiber fabric changed from 12.81 J to 19.51 J,which increased by 52.3 %.The absorption kinetic energy of UHMWPEF single-layer fiber fabric changed from 17.24 J to 28.56 J,which increased by 65.56 %.(4)The results show that the matrix is used to simulate the enhancement effect of STF on the fabric.When the fiber fabric is impacted by the steel bullet,the stress of the fiber fabric with the matrix is higher than that of the fiber fabric without the matrix.The peak stress reaches 835 MPa and 1157 MPa,respectively.The matrix better simulates the effect of STF on the energy and stress transfer in the fiber fabric.Through the stress cloud diagram,it is found that the fiber of the fabric with the matrix is broken earlier than the matrix.This is because the deformation degree of the matrix fracture is greater than the deformation degree of the fabric fiber fracture.