The Rheological Properties Of Shear Thickening Fluid And The Compression Behaviors Of Its Composite

The shear thickening fluid (STF) can be defined as a system whose viscosity increases when certain force is imposed on it. It is the key material to fluid body armor material reported by American Army Research Laboratory, and in the damping, shock, protective materials, control equipment also have important applications.As a new generation of functional textiles, warp-knitted spacer fabric has a good application in physical properties and mechanical compression, damping, etc. It is also widespread concerned as comfortable and environmentally friendly packing materials in new areas.In this thesis mainly prepare nano silica/polyethylene glycol (SiO2/PEG) shear thickening fluid dispersion system. The factors which affect the rheological behavior were studied on rheometer. Composite was prepared by impregnating the STF into the warp-knitted spacer fabrics (WKSF), the mechanical properties of the composite and pure fabric were tested under dynamic impact compression loading. The influences of SiO2salvation and impact velocity on mechanical properties are also studied.The steady rheological behavior showed SiO2/PEG200had good performance of shear thickening. The tests indicated that suspending medium, silica mass fraction, and temperature influenced the rheological behavior. The system showed viscoelastic behavior under dynamic rheological tests. With the change of angle frequency and strain, the storage modulus and loss modulus would also change. Accordingly, shear thickening behavior of the dispersion can be explained by hydrocluster mechanism.The quasi-static compression and dynamic impact tests showed that shear thickening would emerge when the shear rate exceeds the critical value. Under higher impact velocity, the deformation of the composite is much smaller than that of pure WKSF but its energy absorption capability is higher. With the increase of silica mass fraction and impact velocity, the modulus of the composite is also increased. With the increase of dilution ratio by ethanol, the modulus of the composite showed a trend of decrease.