Rheological measurements and normal compression tests on shear thickening fluids below room temperature
This work concentrated on the rheological measurements and normal compression tests of a shear thickening fluid (STF) below room temperature from −20 to 20 °C. The STF was made of 20% of fumed silica and 80% ethylene glycol in weight fraction. Experimental measurements were conducted with a parallel plate MCR301 rheometer. Temperature dependency, steady-state tests, oscillatory fRequency sweep tests, oscillatory shear strain amplitude sweep tests, and normal compression tests were applied on STF, and the testing results were analysed and discussed. The temperature played an important role in the performance of STF. The low temperature increased the STF’s viscosity and shear thickening effect but decreased the STF’s critical shear rate. Frequency was found to contribute to the STF’s phase change from the liquid state to the solid state. The normal compression tests were conducted to determine the equivalent stiffness of STF under different temperatures and various shear rates. The results showed that the STF’s equivalent normal stiffness could be increased by either lowering the applied temperature or increasing the shear rate. A mathematical model was adopted to represent the viscosity of STF in the temperature range from −20 to 20 °C.
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