Modeling Test Method For Shearing Thickening Fluid Modified Fiber Fabric

Kevlar49 aramid fabric itself has high strength,low density,high corrosion resistance and low production cost,which makes it widely used in the field of protection.The impact resistance of fabrics and the friction between fabric yarns and the overall modulus of fabrics are an important relationship.In this paper,the Kevlar49 fiber fabric is modified by Shear Thickening Fluid(STF)to improve the overall impact resistance of the fiber fabric.By comparing the single yarn drawing test and the frame shear test of pure Kevlar49 fiber fabric and STF-Kevlar49 fabric,the mechanism of STF improving the impact resistance of Kevlar49 fiber fabric was discussed.In this paper,the mass fractions of STF were prepared by using SiO2 with particle diameters of 500 nm,1?m,and 2?m as dispersed phase particles and ethylene glycol(EG)as a dispersion medium.The effects of particle size and different mass fraction of different dispersed phase on STF rheology were discussed.The STF system itself has an initial viscosity.As the shear rate increases,the viscosity of the system first decreases gradually,and shear thinning occurs.As the shear rate increases further,the STF viscosity increases rapidly when a critical value is reached.A shear thickening effect occurs.It is found that with the increase of SiO2 particle size at the same mass fraction,the initial viscosity of the STF system decreases,the critical shear rate decreases and the maximum thickening viscosity decreases.With the increase of the mass fraction under the same SiO2 particle size,The initial viscosity of the STF system increases,the critical shear rate decreases,and the maximum thickening viscosity increases.The prepared STF was combined with a single yarn drawing test piece to prepare an STF-Kevlar49 fabric,and a single yarn of pure Kevlar49 fiber fabric and STF-Kevlar49 fabric was subjected to a tensile test.The tensile strength and elastic modulus of the weft yarn obtained from the experiment are larger than that of the warp yarn.The tensile strength of the impregnated STF yarn is slightly smaller than that of the pure Kevlar49 fiber,but the elastic modulus is slightly larger than that of the pure Kevlar49 fiber yarn.The single yarn drawing test of pure Kevlar49 fiber fabric and STF-Kevlar49 fabric showed that the maximum drawing load was much larger than that of pure Kevlar49 fiber fabric because STF increased the friction between the yarns and increased the yarn.The difficulty of slipping out.The digital image correlation technology(DIC)was used to measure the shear deformation process of the fabric during the yarn drawing process.It was found that the shear deformation of the fiber fabric during the drawing of the single yarn was symmetrical with respect to the drawn yarn,and the deformation of the experimental part of the drawn yarn was closer.The deformation of the STF-Kevlar49 fabric test piece is larger than that of the pure Kevlar49 fiber fabric,because the tensile force of the STF-Kevlar49 fabric test piece is increased,resulting in a large overall deformation of the test piece.Single yarn drawing test for different SiO2 particle size STF and STF impregnated fabrics with different mass fractions can be used to obtain the maximum load drawing load from 2?m>500nm>1?m,which is due to the experimental yarn of 2?m and 500 nm.The friction between the wires is greater.As the mass fraction increases,the shear thickening effect of the STF is more obvious.The greater the viscosity of the system,the greater the friction between the yarns,and the corresponding pulling load is larger.For the STF impregnated fabric with parameters,as the speed increases,the maximum pull load first increases and then decreases,which corresponds to the shear thinning and thickening rheological properties of the STF.The single yarn pull test of the experimental parts with different wave numbers found that the maximum drawing load of the experimental piece increased with the increase of the wave number.In order to understand the effect of STF on the shear deformation of Kevlar49 fiber fabric,pure Kevlar49 fiber fabric and STF-Kevlar49 fabric were prepared into cross-shaped shear test pieces,and the experimental parts were subjected to frame shearing experiments to study how STF can improve the resistance of Kevlar49 fiber fabric.Deformability,the experiment found that pure Kevlar49 fiber fabric and STF-Kevlar49 fabric have little difference in stiffness during low-speed shearing,but the elastic modulus of STF-Kevlar49 fabric is much higher than that of pure Kevlar49 fabric during high-speed shearing,which is related to STF.Shear thickening effects are closely related at high speeds.