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Heinrich M. Jaeger - One of the best experts on this subject based on the ideXlab platform.
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Shear Thickening and jamming of dense suspensions the roll of friction
Physical Review Letters, 2020Co-Authors: Abhinendra Singh, Christopher Ness, Ryohei Seto, Juan J De Pablo, Heinrich M. JaegerAbstract:Particle-based simulations of discontinuous Shear Thickening (DST) and Shear jamming (SJ) suspensions are used to study the role of stress-activated constraints, with an emphasis on resistance to gearlike rolling. Rolling friction decreases the volume fraction required for DST and SJ, in quantitative agreement with real-life suspensions with adhesive surface chemistries and "rough" particle shapes. It sets a distinct structure of the frictional force network compared to only sliding friction, and from a dynamical perspective leads to an increase in the velocity correlation length, in part responsible for the increased viscosity. The physics of rolling friction is thus a key element in achieving a comprehensive understanding of strongly Shear-Thickening materials.
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Shear Thickening in highly viscous granular suspensions
EPL, 2014Co-Authors: Sayantan Majumdar, Eric Brown, Heinrich M. JaegerAbstract:We experimentally investigate Shear Thickening in dense granular suspensions under oscillatory Shear. Directly imaging the suspension-air interface, we observe dilation beyond a critical strain and the end of Shear Thickening as the maximum confining stress is reached and the contact line moves. Analyzing the Shear profile, we extract the viscosity contributions due to hydrodynamics , dilation and sedimentation . While governs the Shear thinning regime, and together determine the Shear Thickening behavior. As the suspending liquid's viscosity varies from 10 to 1000 cSt, is found to compete with and soften the discontinuous nature of Shear Thickening.
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Shear Thickening in concentrated suspensions phenomenology mechanisms and relations to jamming
Reports on Progress in Physics, 2014Co-Authors: Eric Brown, Heinrich M. JaegerAbstract:Shear Thickening is a type of non-Newtonian behavior in which the stress required to Shear a fluid increases faster than linearly with Shear rate. Many concentrated suspensions of particles exhibit an especially dramatic version, known as Discontinuous Shear Thickening (DST), in which the stress suddenly jumps with increasing Shear rate and produces solid-like behavior. The best known example of such counter-intuitive response to applied stresses occurs in mixtures of cornstarch in water. Over the last several years, this Shear-induced solid-like behavior together with a variety of other unusual fluid phenomena has generated considerable interest in the physics of densely packed suspensions. In this review, we discuss the common physical properties of systems exhibiting Shear Thickening, and different mechanisms and models proposed to describe it. We then suggest how these mechanisms may be related and generalized, and propose a general phase diagram for Shear Thickening systems. We also discuss how recent work has related the physics of Shear Thickening to that of granular materials and jammed systems. Since DST is described by models that require only simple generic interactions between particles, we outline the broader context of other concentrated many-particle systems such as foams and emulsions, and explain why DST is restricted to the parameter regime of hard-particle suspensions. Finally, we discuss some of the outstanding problems and emerging opportunities.
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The role of dilation and confining stresses in Shear Thickening of dense suspensions
Journal of Rheology, 2012Co-Authors: Eric Brown, Heinrich M. JaegerAbstract:Many densely packed suspensions and colloids exhibit a behavior known as Discontinuous Shear Thickening in which the Shear stress jumps dramatically and reversibly as the Shear rate is increased. We performed rheometry and video microscopy measurements on a variety of suspensions to determine the mechanism for this behavior. We distinguish Discontinuous Shear Thickening from inertial effects by showing that the latter are characterized by a Reynolds number but are only found for lower packing fractions and higher Shear rates than the former. Shear profiles and normal stress measurements indicate that, in the Shear Thickening regime, stresses are transmitted through frictional rather than viscous interactions. We come to the surprising conclusion that for concentrated suspensions such as cornstarch in water which exhibit the phenomenon of Discontinuous Shear Thickening, the local constitutive relation between stress and Shear rate is not necessarily Shear Thickening. If the suspended particles are heavy en...
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Shear Thickening and jamming in densely packed suspensions of different particle shapes
Physical Review E, 2011Co-Authors: Eric Brown, Nicole A Forman, Hanjun Zhang, Benjamin W Maynor, Douglas E Betts, Joseph M Desimone, Heinrich M. JaegerAbstract:We investigated the effects of particle shape on Shear Thickening in densely packed suspensions. Rods of different aspect ratios and nonconvex hooked rods were fabricated. Viscosity curves and normal stresses were measured using a rheometer for a wide range of packing fractions for each shape. Suspensions of each shape exhibit qualitatively similar discontinuous Shear Thickening. The logarithmic slope of the stress vs Shear rate increases dramatically with packing fraction and diverges at a critical packing fraction ${\ensuremath{\varphi}}_{c}$ which depends on particle shape. The packing fraction dependence of the viscosity curves for different convex shapes can be collapsed when the packing fraction is normalized by ${\ensuremath{\varphi}}_{c}$. Intriguingly, viscosity curves for nonconvex particles do not collapse on the same set as convex particles, showing strong Shear Thickening over a wider range of packing fraction. The value of ${\ensuremath{\varphi}}_{c}$ is found to coincide with the onset of a yield stress at the jamming transition, suggesting the jamming transition also controls Shear Thickening. The yield stress is found to correspond with trapped air in the suspensions, and the scale of the stress can be attributed to interfacial tension forces which dramatically increase above ${\ensuremath{\varphi}}_{c}$ due to the geometric constraints of jamming. Using this connection we show that the jamming transition can be identified by simply looking at the surface of suspensions. The relationship between Shear and normal stresses is found to be linear in both the Shear Thickening and jammed regimes, indicating that the Shear stresses come from friction. In the limit of zero Shear rate, normal stresses pull the rheometer plates together due to the surface tension of the liquid below ${\ensuremath{\varphi}}_{c}$, but push the rheometer plates apart due to jamming above ${\ensuremath{\varphi}}_{c}$.
Vikram Rathee - One of the best experts on this subject based on the ideXlab platform.
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Shear Thickening behavior in dense repulsive and attractive suspensions of hard spheres
'Royal Society of Chemistry (RSC)', 2021Co-Authors: Vikram Rathee, Alessandro Monti, Marco E. Rosti, Amy Q. ShenAbstract:Shear Thickening in stable dense colloidal suspensions is a reversible phenomenon and no hysteresis is observed in the flow curve measurements. However, a reduction in the stability of colloids promotes particle aggregation and introduces a time dependent rheological response. In this work, by using a model colloidal system of hard spherical silica particles (average diameter of 415 nm) with varying particle volume fractions 0.2 ≤ ϕ ≤ 0.56, we study the effect of particle stability on the hysteresis of the Shear Thickening behavior of these suspensions. The particle stability is manipulated by adding a simple monovalent salt (sodium chloride) in the silica suspension with varying concentrations α ∈ [0,0.5] M. For repulsive and weakly attractive suspensions, the flow behavior is history independent and the Shear Thickening behavior does not exhibit hysteresis. However, significant hysteresis is observed in rheological measurements for strongly attractive suspensions, with Shear history playing a critical role due to the dynamic nature of particle clusters, resulting in time dependent hysteresis behavior. By performing numerical simulations, we find that this hysteresis behavior arises due to the competition among Shear, electrostatic repulsive, van der Waals attractive, and frictional contact forces. The critical Shear stress (i.e., the onset of Shear Thickening) decreases with increasing salt concentrations, which can be captured by a scaling relationship based on the force balance between particle–particle contact force and electrostatic repulsive force. Our combined experimental and simulation results imply the formation of particle contacts in our Sheared suspensions
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contact networks enhance Shear Thickening in attractive colloid polymer mixtures
Physical Review Letters, 2019Co-Authors: Nayoung Park, Vikram Rathee, Daniel L Blair, Jacinta C ConradAbstract:Increased Shear thinning arising due to strong attractive interactions between colloidal particles is thought to obscure Shear Thickening. Here, we demonstrate how moderate attractions, induced by adding a nonadsorbing polymer, can instead enhance Shear Thickening. We measure the rheology of colloidal suspensions at a constant particle volume fraction of ϕ=0.40 with dilute to weakly semidilute concentrations of three polyacrylamide depletants of different molecular weights. Suspensions containing large polymer exhibit increased Shear Thickening and positive first normal stress differences at high Shear stress, and increased heterogeneous fluctuations in the boundary stress. These results are consistent with a friction-based model for Shear Thickening, suggesting that the presence of large, extended polymers induces the formation of near-spanning networks of interparticle contacts.
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localized stress fluctuations drive Shear Thickening in dense suspensions
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Vikram Rathee, Daniel L Blair, Jeffrey S UrbachAbstract:Dense particulate suspensions exhibit a dramatic increase in average viscosity above a critical, material-dependent Shear stress. This Thickening changes from continuous to discontinuous as the concentration is increased. Using direct measurements of spatially resolved surface stresses in the continuous Thickening regime, we report the existence of clearly defined dynamic localized regions of substantially increased stress that appear intermittently at stresses above the critical stress. With increasing applied stress, these regions occupy an increasing fraction of the system, and the increase accounts quantitatively for the observed Shear Thickening. The regions represent high-viscosity fluid phases, with a size determined by the distance between the Shearing surfaces and a viscosity that is nearly independent of Shear rate but that increases rapidly with concentration. Thus, we find that continuous Shear Thickening arises from increasingly frequent localized discontinuous transitions between distinct fluid phases with widely differing viscosities.
Geert De Schutter - One of the best experts on this subject based on the ideXlab platform.
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Why is fresh self-compacting concrete Shear Thickening?
Cement and Concrete Research, 2009Co-Authors: Dimitri Feys, Ronny Verhoeven, Geert De SchutterAbstract:Abstract The rheological properties of fresh concrete are mostly described by means of the Bingham model. For self-compacting concrete, the Bingham model is applicable in a lot of cases, but some authors report that the rheological behaviour is non-linear. The apparent viscosity increases with increasing Shear rate and the SCC shows Shear Thickening behaviour. Shear Thickening becomes important in operations occurring at high Shear rates, like mixing and pumping. In these cases, Shear Thickening should not be forgotten in order to avoid breaking of the mixer, pump or pipes. This paper will describe two possible theories for Shear Thickening behaviour of SCC, based on results published in the rheology literature. The first theory consists of the formation of so-called (hydro-)clusters, which are temporary assemblies of small particles. These clusters start being formed from a certain Shear stress on: the critical Shear stress. They cause the viscosity to increase with increasing Shear rate. A second theory is based on grain inertia, where a part of the Shearing force is transmitted through direct momentum transfer between solid particles. Results on cement pastes prove that the grain inertia theory is not the main cause of Shear Thickening in self-compacting concrete. The influence of several parameters on the Shear Thickening behaviour of SCC can be well explained by means of the cluster theory.
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fresh self compacting concrete a Shear Thickening material
Cement and Concrete Research, 2008Co-Authors: Dimitri Feys, Ronny Verhoeven, Geert De SchutterAbstract:Abstract In literature, the rheological properties of concrete have been investigated thoroughly, resulting in a simple description, in steady state, by means of the Bingham model. Self compacting concrete shows a lower yield stress, which in some cases is very close to zero, or can even appear to be negative when extrapolating the Bingham model. In the latter case, the Bingham model is not valid and other solutions must be found. In this paper, the non-linearity – or Shear Thickening – in the rheological behaviour of fresh SCC is described with the modified Bingham model, after the elimination of possible measurement artefacts. Analysis indicates that Shear Thickening is mainly correlated with the type of superplasticizer, the type of filler, the W/P-ratio and the slump flow of the concrete.
Yu Tian - One of the best experts on this subject based on the ideXlab platform.
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Shear thinning and Shear Thickening characteristics in electrorheological fluids
Smart Materials and Structures, 2014Co-Authors: Jile Jiang, Yonggang Meng, Yingdan Liu, Lei Shan, Xiangjun Zhang, Hyoung Jin Choi, Yu TianAbstract:The electrorheology (ER) of suspensions based on polystyrene/polyaniline (PS/PANI) core/shell structured microspheres and those based on disk-like zeolite particles at different electric fields and particle volume fractions have been studied, respectively. Both types of ER fluids showed abrupt Shear Thickening under high electric fields and low Shear rates, as well as Shear thinning when the Shear rate increased. A normalized method that considers the effects of electric field strength, Shear rate and particle volume fraction was proposed to compare the rheological curves of the two ER fluids. The curves evaluated from the normalization method showed similar Shear thinning at low Shear rates and the hydrodynamic effect at high Shear rates. Shear thinning represents the structure destroyed by Shearing, and Shear Thickening at low Shear regions indicates the dramatic structure change. The particle volume fraction and structure factor effects demonstrate that the mechanical contact between particles and the wall of the electrodes is crucial to the Shear strength of ER fluids, indicating an electric/magnetic field modulated friction mechanism of the ER and magnetorheological (MR) effects.
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reversible Shear Thickening at low Shear rates of electrorheological fluids under electric fields
Physical Review E, 2011Co-Authors: Yu Tian, Minliang Zhang, Jile Jiang, Noshir S Pesika, Hongbo Zeng, Jacob N Israelachvili, Yonggang Meng, Shizhu WenAbstract:By Shearing electrorheological (ER) fluids between two concentric cylinders, we show a reversible Shear Thickening of ER fluids above a low critical Shear rate (1 s${}^{\ensuremath{-}1}$) and a high critical electric field strength ($100$ V/mm), which can be characterized by a critical apparent viscosity. Shear Thickening and electrostatic particle interaction-induced interparticle friction forces are considered to play an important role in the origin of lateral Shear resistance of ER fluids, while the applied electric field controls the extent of Shear Thickening. The electric-field-controlled reversible Shear Thickening has implications for high-performance electrorheological -magnetorheological fluid design, clutch fluids with high friction forces triggered by applying a local electric field, other field-responsive materials, and intelligent systems.
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a Shear Thickening phenomenon in magnetic field controlled dipolar suspensions
Applied Physics Letters, 2010Co-Authors: Yu Tian, Jile Jiang, Yonggang Meng, Shizhu WenAbstract:A Shear Thickening phenomenon in dipolar suspensions of magnetorheological (MR) fluid is reported. The stress of the MR fluid abruptly decreases when the applied magnetic field increases to above a critical value under a small constant Shear rate. It abruptly increases when the Shear rate is higher than a critical value under a constant magnetic field, accompanied by a change in normal stress during Shear Thickening or unShear Thickening processes. A Shear-thickened structure is important for an MR fluid to obtain a high yield stress, which is beyond the prediction of a traditional dipole or multipole interaction model.
Daniel L Blair - One of the best experts on this subject based on the ideXlab platform.
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contact networks enhance Shear Thickening in attractive colloid polymer mixtures
Physical Review Letters, 2019Co-Authors: Nayoung Park, Vikram Rathee, Daniel L Blair, Jacinta C ConradAbstract:Increased Shear thinning arising due to strong attractive interactions between colloidal particles is thought to obscure Shear Thickening. Here, we demonstrate how moderate attractions, induced by adding a nonadsorbing polymer, can instead enhance Shear Thickening. We measure the rheology of colloidal suspensions at a constant particle volume fraction of ϕ=0.40 with dilute to weakly semidilute concentrations of three polyacrylamide depletants of different molecular weights. Suspensions containing large polymer exhibit increased Shear Thickening and positive first normal stress differences at high Shear stress, and increased heterogeneous fluctuations in the boundary stress. These results are consistent with a friction-based model for Shear Thickening, suggesting that the presence of large, extended polymers induces the formation of near-spanning networks of interparticle contacts.
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localized stress fluctuations drive Shear Thickening in dense suspensions
Proceedings of the National Academy of Sciences of the United States of America, 2017Co-Authors: Vikram Rathee, Daniel L Blair, Jeffrey S UrbachAbstract:Dense particulate suspensions exhibit a dramatic increase in average viscosity above a critical, material-dependent Shear stress. This Thickening changes from continuous to discontinuous as the concentration is increased. Using direct measurements of spatially resolved surface stresses in the continuous Thickening regime, we report the existence of clearly defined dynamic localized regions of substantially increased stress that appear intermittently at stresses above the critical stress. With increasing applied stress, these regions occupy an increasing fraction of the system, and the increase accounts quantitatively for the observed Shear Thickening. The regions represent high-viscosity fluid phases, with a size determined by the distance between the Shearing surfaces and a viscosity that is nearly independent of Shear rate but that increases rapidly with concentration. Thus, we find that continuous Shear Thickening arises from increasingly frequent localized discontinuous transitions between distinct fluid phases with widely differing viscosities.
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rheological signature of frictional interactions in Shear Thickening suspensions
Physical Review Letters, 2016Co-Authors: Daniel L Blair, John R. Royer, Steven D. HudsonAbstract:Colloidal Shear Thickening presents a significant challenge because the macroscopic rheology becomes increasingly controlled by the microscopic details of short ranged particle interactions in the Shear Thickening regime. Our measurements here of the first normal stress difference over a wide range of particle volume fractions elucidate the relative contributions from hydrodynamic lubrication and frictional contact forces, which have been debated. At moderate volume fractions we find ${N}_{1}l0$, consistent with hydrodynamic models; however, at higher volume fractions and Shear stresses these models break down and we instead observe dilation (${N}_{1}g0$), indicating frictional contact networks. Remarkably, there is no signature of this transition in the viscosity; instead, this change in the sign of ${N}_{1}$ occurs while the Shear Thickening remains continuous. These results suggest a scenario where Shear Thickening is driven primarily by the formation of frictional contacts, with hydrodynamic forces playing a supporting role at lower concentrations. Motivated by this picture, we introduce a simple model that combines these frictional and hydrodynamic contributions and accurately fits the measured viscosity over a wide range of particle volume fractions and Shear stress.