Micrograph of the cornstarch particles.
Apparent viscosity vs shear rate when performing a step stress test in a vane-in-cup geometry.
Dimensionless velocity profile in the gap obtained by MRI measurements. Inset: the shear rate at the interface between sheared and unsheared regions is given by the slope of the velocity profile at that point, taken of course in the moving part of the material.
(a) Local shear stress as a function of the local shear rate. The line is a fit to the Bingham model: with , . (b) Local concentration profiles in the Couette gap geometry for a cornstarch suspension sheared at various rotational velocities ranging from 3 to 9 rpm.
Example of a non-flowing region or “dead zone” in parallel-plate geometry.
Role of surplus of paste on the shear-thickening transition: Evolution of normal stress and viscosity as a function of the applied shear rate.
(a) Elastic modulus (G′) and loss modulus (G″) in the 44% volume fraction suspension as a function of shear strain for an imposed shear stress (0.001–100 Pa) at 1 Hz in a vane geometry. (b) Critical strain vs gap and frequency.
Time evolution for a applied shear rate of: (a) the gap size and the normal stress; (b) normal (circles) and shear stresses (squares). The rheometer is set to change the rotation rate of the tool through a feedback loop to make sure that the shear rate is constant, even though the gap is changing.
(a) Apparent viscosity and normal stress as a function of shear rate for different gaps in millimeter. Measurements were made with a parallel-plate rheometer (Bohlin C-VOR 200) with radius R = 20 mm. (b) Evolution of the critical shear rate, a function of the gap. The error bars correspond to the uncertainty (reproducibility) of the experiments.
Variation of the gap according to the shear rate.
Viscosity as a function of a shear rate for different concentrations. (b) Critical shear stress of shear thickening vs concentration in different measurement geometries. Inset: critical shear rate of shear thickening vs concentration.
Proportionality between normal stress and shear stress in the shear-thickening regime for the 44% volume fraction suspension.
Solid–liquid–solid transition; apparent viscosity vs stress when performing a step stress test.
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