| The special three-dimensional structure of the spacer fabric possesses excellent compression resilience,damping energy absorption and moisture permeability,so it is the first choice for cushioning protection materials.However,due to the problem that the spacer fabric is easy to lodging when subjected to external forces,the compressive protection capability is limited.Then if the warp-knitted spacer fabric is used as the reinforcing body,the buffer damping excellent RTV silicone rubber and shearing thickening fluid(STF)are used as the filling reinforcing materials to prepare the flexible buffer composite spacer fabric and study its cushioning energy absorption,which is expected to be used for cushioning with sole(midsole)material.Therefore the main research contents include:(a)Modification of filler material RTV silicone rubber by adding structure control agent,and analyzing the microscopic mechanism of structural control agent in adjusting silicone rubber performance by infrared spectrometer;and using rheological instrument to analyze the different Si O2 mass fraction steady rheological properties of STF.(b)Quasi-static compression test and low speed impact test of filled silicone rubber spacer fabric composites are carried out to analyze the effect of three kinds of indenters on the static compression behavior of spacer fabric and its composite materials,and the effect of mass fraction of the structural control agent under low-speed impact on its cushioning energy absorption.(c)The quasi-static compression and low speed impact properties of the spacer fabric filled with shear-thickening composite were tested,and the cushioning deformation mechanism and energy absorption mechanism of the fabric and composite under different impact compression speeds were analyzed.The results are as follows:(1)The infrared spectra of the modified silicone rubber with the structure control agent were basically the same as those of the pure silicone rubber without the structure control agent,and the structure control agent and the silicone rubber were physically mixed.The steady-state rheological properties of shear thickening fluid showed shear thickening effect,and the different Si O2 mass fraction,the critical shear rate of shearing thickening effect of shear thickening liquid dispersion system was different.At the same temperature,the larger the mass fraction of Si O2 particles in the system,the smaller the shear rate that reaches the critical shear point,and the greater the viscosity of the system.At the same time,the temperature has an effect on the steady-state rheological properties of STF system.Under the same Si O2 mass fraction,the higher the temperature,the larger the shear rate reaching the critical shear point,the smaller the viscosity of the system.Therefore,the impact of environmental factors should be considered in practical application.(2)The quasi-static compressive force-strain curve of composites was basically the same as that of warp-knitted spacer fabric,including the initial stage,the elastic stage,the platform stage and the compaction stage.According to the bivariate correlation analysis of SPSS software,the filling silicone rubber spacer fabric composite had significant correlation at 0.01 confidence level among the four characteristic indexes under three indenter compression of flat plate,spherical and last.The correlation between flat compression and shoe last compression characteristic index was the highest,and the correlation with the spherical compression was poor,and the correlation between the spherical and the last shoe compression was higher than that of the flat plate.The results of multivariate linear regression analysis showed that there was a significant linear relationship between the structural parameters of spacer fabric and its compression resilience and compression support.The thickness of fabric has the greatest effect on its cushioning performance and is positively correlated,while the density of spacer wire has the least influence on the compression performance and is negatively correlated.When the shape of the indenter was the same,the larger the mass fraction of the structure control agent was,the smaller the compressive load peak of the silicone rubber composite was and the greater the strain was and the better the cushioning performance was.When the shape of the indenter was different,the strain of the composite material with the same mass fraction of the structure control agent was filled,the strain under the compression of the flat plate indenter was the smallest,and the strain under the compression of the spherical head was the largest.Among them,the pressure on the last shoe press compression and flat plate pressure closer.Shear thickening did not reach its critical shear rate for shear thickening filled spacer fabric at three compression speeds.However,with the increase of compression speed,the compressive load value and hysteresis of STF composites increased,STF has obvious strain rate effect.(3)Compared with the quasi-static compression,the low speed impact curve of the spacer fabric lacks the initial stage with a small curve slope.After the warp-knitted spacer fabric filled with silicone rubber and shear thickening fluid,the impact load-time curves were basically the same and there was only one stage.The load and time were linearly and positively correlated,the modulus was large and the strain was small,more energy was absorbed within the same strain,and the curve was obviously different from the pure fabric.The addition of structural control agent played a certain role in the cushioning ability of silicone rubber composites.At the same impact height,with the increase of the content of the structure control agent,the peak value of the load of the composite gradually became smaller.At different impact heights,STF exhibited different cushioning properties.The modulus of composites increased with the increased of impact height,and the shear thickening fluid had significant shear thickening effect.STF filled spacer fabric composites have some relationship between quasi-static compression and low speed impact.Through correlation analysis,there were two indicators between static compression and low speed impact correlation at the confidence level of 0.01,that is,the correlation coefficient between static compression modulus and low speed impact load peak,and the low speed impact modulus the correlation coefficient were significant,the correlation between other indexes was not significant. |
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