Yield stress and thixotropy: on the difficulty of measuring yield stresses in practice

Møller, Peder; Mewis, Jan; Bonn, Daniel

doi:10.1039/b517840a

Cited by 496 publications

(383 citation statements)

References 37 publications

(100 reference statements)

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“…The modeling, considering viscous interactions, was not able to produce a shear-thickening behavior. This result is consistent with the fact that the shear thickening response is not an intrinsic bulk material response but is related to interaction with the boundaries which confine the suspension (Brown and Jaeger [15] The interplay between yield stress and thixotropy is discussed in Møller et al [16] They argue that below a critical shear rate, all the flow is localized in a region near the shearing wall, and if the globally imposed shear rate is increased it is not the shear rate in the sheared region that increases but rather the extent of the sheared region which grows -to fill the entire gap of the shear cell exactly at the critical shear rate. (Note that this localization is distinct from wall slip).…”

Section: Connection With Discontinuous Shear Thickening In Dense Ssupporting

confidence: 82%

Does Shear Thickening Occur in Semisolid Metals?

Atkinson

Favier

2016

Metall Mater Trans A

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In the various forms of semisolid processing such as thixoforming and thixoforging, the entry into the die occurs in a fraction of a second so it is the transient rheological behavior which governs the initial stages of flow. In experiments in the literature, this rheological behavior is probed through applying rapid transitions in shear rate under isothermal conditions. There is contradictory evidence as to whether the behavior during these transitions is shear thinning or shear thickening, although it is clear that once in the die the material is thinning. Here the data in the literature are reanalyzed to obtain a rationalization of the contradictions which has not previously been available. It is argued that if a suspension is initially in a disagglomerated state (i.e., one which is initially sheared), the instantaneous behavior with a jump-up in shear rate is shear thickening (even if the long-term steady-state behavior is shear thinning) provided the fraction solid is greater than about 0.36 and the final shear rate at the end of the jump is greater than about 100 s À1 . If the jump-up in shear rate is made from rest then yield masks the shear thickening.

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Section: Connection With Discontinuous Shear Thickening In Dense Ssupporting

confidence: 82%

Does Shear Thickening Occur in Semisolid Metals?

Atkinson

Favier

2016

Metall Mater Trans A

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“…If the resulting driving force is smaller than the yield stress the drainage stops. The yield stress is considered sometimes currently as a rather controversial concept and it is claimed sometimes that the non-Newtonian liquids can flow under any stress whatever low it is [34,35]. However, on the time scale of the practical interest of foams drainage below such flow can be neglected.…”

Section: Bulk Rheologymentioning

confidence: 99%

Bulk and surface rheology of Aculyn™ 22 and Aculyn™ 33 polymeric solutions and kinetics of foam drainage

Bureiko

Trybała

Huang

et al. 2013

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Citation: BUREIKO, A., 2013 AbstractExperimental investigations of both bulk and surface rheology of solutions of commercially available polymers Aculyn TM 22 and Aculyn TM 33 in presence of sodium chloride are performed in a wide range of the polymer and salt concentrations. It is shown that the bulk viscosity and the surface viscoelastic modulus of solutions of both polymers increases with the increase of polymer concentration and the decrease of the salt concentration. Solutions of both polymers demonstrate very good foamability and form stable foams. Foam drainage is governed mainly by the bulk viscosity when the latter is in the range of 100-500 mPa·s.

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“…Coussot et al [44] provided evidence for an interplay between yield stress and thixotropy. Møller et al [45] concluded that yield stress and thixotropy of a fluid have the same physical origin. The measurement of the yield stress not only depends on the duration of the experiment, but also on the history of the fluid deformation.…”

Section: Rheometrymentioning

confidence: 99%

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Cochard

Ancey

2009

Journal of Non-Newtonian Fluid Mechanics

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a b s t r a c tWe report experimental results related to the dam-break problem for viscoplastic fluids. Using image processing techniques, we were able to accurately reconstruct the free-surface evolution of fixed volumes of fluid suddenly released a plane. We used Carbopol Ultrez 10 as a viscoplastic material; its rheological behavior was closely approximated by a Herschel-Bulkley model for a fairly wide range of shear-rates. Varying the Carbopol concentration allowed us to change the yield stress and bulk viscosity. The yield stress ranged from 78 to 109 Pa, producing Bingham numbers in the 0.07-0.35 range. We investigated the behavior of a 43-kg mass released on a plane, whose inclination ranged from 0 • to 18 • . For each run, we observed that the behavior was nearly the same: at short times, the mass accelerated vigorously on gate opening and very quickly reached a nearly constant velocity. At time t = 1 s, independently of plane inclination and yield stress, the mass reached a near-equilibrium regime, where the front position varied as a power function of time over several decades. We did not observe any run-out phase, during which the mass would have gradually come to a halt. The similarity in the flow behavior made it possible to derive an empirical scaling for the front position in the form x f = t 0.275(sin˛) 1/3 (sin˛) 5/4 , where˛and t denote plane inclination and time, respectively, and which holds for sloping beds (˛> 0).

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Yield stress and thixotropy: on the difficulty of measuring yield stresses in practice

Cited by 496 publications

References 37 publications

Does Shear Thickening Occur in Semisolid Metals?

Does Shear Thickening Occur in Semisolid Metals?

Bulk and surface rheology of Aculyn™ 22 and Aculyn™ 33 polymeric solutions and kinetics of foam drainage

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

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