Year

2014

Degree Name

Doctor of Philosophy

Department

School of Mechanical, Materials and Mechatronic Engineering

Abstract

This thesis focused on the properties of shear thickening/stiffened materials and their applications.

The fabrication of shear thickening fluid (STF) made from ethylene glycol and fumed silica was studied and its properties were measured with a rheometer under state steady and dynamic test conditions. The temperature effect on shear thickening fluid was also investigated and a numerical function was proposed to express the relationship between the temperature, viscosity, and concentration of fumed silica.

Adding fumed silica to a currently used commercial electrolyte resulted in a shear thickening electrolyte with a higher ionic conductivity than the commercial electrolyte. Furthermore, the batteries using this shear thickening electrolyte provided extra mechanical protection than those batteries containing commercial electrolyte.

The magnetorheological shear thickening fluids (MRSTFs) can be gained by combining the magnetorheological fluid (MRF) and shear thickening fluid. This new MRSTFs were tested and revealed both a magnetorheological effect and shear thickening properties. Moreover, the damper filled with MRSTF had unique properties coming from both magnetorheological fluid and shear thickening fluid.

Shear stiffened elastomers (SSEs) made of silicone rubber and silicone oil were fabricated and observed by scanning electron microscope (SEM). A cluster structure was observed and the sample with a higher concentration of silicone oil had longer clusters of silicone rubber. The rheology of shear stiffened elastomers was measured with a rheometer and it showed that the sample with a higher concentration of silicone oil had a longer linear range and a lower shear modulus. During the dynamic frequency sweep tests when the shear strain amplitude was above a critical value, the shear stiffened elastomer sample was seen to change from solid to liquid and then from liquid to solid, which was the onset of shear stiffened.

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