Densely packed particle suspensions exhibit interesting non-Newtonian rheological properties such as discontinuous shear thickening (DST) when a suspension above a critical particle volume fraction is subjected to a shear stress greater than a critical value. Such behavior arises from the build-up of frictional contact forces between particles greater than hydrodynamic forces such that the viscosity of the suspension increases dramatically. Both experiments and simulation have shown that particle-particle and particle-medium interactions are important factors governing the critical volume fraction and shear stress. This talk presents recent biaxial shear experiments utilizing an orthogonal superposition technique on dense hard-sphere suspensions. We investigate commercially available glass microspheres and synthesized silica nanosphere suspensions with different particle surface chemistry and suspending medium. Our biaxial shear protocol is demonstrated to be a robust method on elucidating microstructural changes related with DST as well as providing guidance to shear thickening fluid applications.

Rheological properties of hard-sphere suspensions in biaxial shear flow

2019 Spring National Meeting

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