Roughness-dependent tribology effects on discontinuous shear thickening

Hsu, Chiao Peng; Ramakrishna, Shivaprakash N.; Zanini, Michele; Spencer, Nicholas D.; Isa, Lucio

doi:10.1073/pnas.1801066115

Cited by 131 publications

(119 citation statements)

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“…For simplicity here we consider jamming (unjamming) to be a rapid increase (decrease) in rigidity that is typically associated with an increase (decrease) in volume fraction φ toward (away from) a critical value φ c . The nature of this transition, however, is sensitive to particle contacts and interactions [123][124][125] and interparticle friction [126,127], factors that are important for geophysicallyrelevant properties such as dilatancy [128].…”

Section: Soft Matter Concepts In Earth Materialsmentioning

confidence: 99%

“…The unifying framework of µ(I) rheology is appealing in its simplicity, and recent work has demonstrated how it may be generalized to account for: Non-Newtonian carrier fluids [226]; thermal effects [227]; and cohesion [228,229]. On the other hand, qualitative changes in flow behavior may be induced by: particle polydispersity and shape [230,231], surface roughness [124], repulsion [130] and hydrogen bonding [125], at-traction [74], and capillary forces [232]. All of these factors ultimately influence particle microstructure, and explicit accounting for these changes in bulk continnum models is a challenge.…”

Section: Outstanding Problemsmentioning

confidence: 99%

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Viewing Earth’s surface as a soft-matter landscape

Jerolmack

Daniels

2019

Nat Rev Phys

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The Earth's surface is composed of a staggering diversity of particulate-fluid mixtures: dry to wet, dilute to dense, colloidal to granular, and attractive to repulsive particles. This material variety is matched by the range of relevant stresses and strain rates, from laminar to turbulent flows, and steady to intermittent forcing, leading to anything from rapid and catastrophic landslides to the slow relaxation of soil and rocks over geologic timescales. Geophysical flows sculpt landscapes, but also threaten human lives and infrastructure. From a physics point of view, virtually all Earth and planetary landscapes are composed of soft matter, in the sense they are both deformable and sensitive to collective effects. Geophysical materials, however, often involve compositions and flow geometries that have not yet been examined in physics. In this review we explore how a soft-matter perspective has helped to illuminate, and even predict, the rich dynamics of Earth materials and their associated landscapes. We also highlight some novel phenomena of geophysical flows that challenge, and will hopefully inspire, more fundamental work in soft matter.

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Section: Soft Matter Concepts In Earth Materialsmentioning

confidence: 99%

Section: Outstanding Problemsmentioning

confidence: 99%

Viewing Earth’s surface as a soft-matter landscape

Jerolmack

Daniels

2019

Nat Rev Phys

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“…The consensus from these studies, a substantial fraction of which are on suspension of spherical or compact particles, suggests that while the hydrocluster mechanism [7,8] can account for a nominal increase in η, a larger increase stems from particles forming a stressinduced frictional contact network [9][10][11][12][13][14][15][16][17][18]. This has resulted in a multitude of strategies where shear-thickening is passively controlled by altering particle tribological properties [19] or actively tuned through complex mechanical perturbations that disrupt the formation of force chains [20]. Even though altering the particle shape is a powerful means to control rheological response [21,23], very little is known about the mechanism of shear-thickening in suspensions of anisotropic particles.…”

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confidence: 99%

Role of particle orientational order during shear thickening in suspensions of colloidal rods

et al. 2020

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There is now convincing evidence that inter-particle frictional contacts are essential for observing shear-thickening in concentrated suspensions of compact particles. While this has inspired many strategies to tailor the rheology in these systems, in the more general case, viz-á-viz suspensions of anisotropic particles, the mechanism of shear-thickening remains unclear. Here through simultaneous measurements of the bulk viscosity and the first Normal stress difference, we show that strong shear thickening in suspensions of colloidal rods is accompanied by large positive normal stresses, indicating the formation of a system-spanning frictional contact network. We also find that flow in the shear-thickening regime is unsteady and shows a rather rich time-dependence. By carrying out single particle-resolved confocal rheology measurements, we provide compelling evidence that this rheological chaos arises from a strong coupling between the imposed flow and particle orientational order. Building on these observations, we designed colloidal rods with temperature-tunable tribological properties and demonstrate the feasibility of achieving in-situ control over suspension rheology. These findings show that the interplay between orientational order and frictional interactions plays a critical role in the shear thickening of dense suspensions of colloidal rods.

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“…Left: Relative viscosity as a function of the shear rate for frictionless dimers with aspect ratio α = 2, for several volume fractions φ = 0.4, 0.45, 0.5 and 0.54. Right: Angles θ and ϕ characterizing the director (see text for definitions) as a function of the applied stress τ/σ r , for the corresponding simulations at φ = 0.5 in the left panel Hsu et al, 2018]…”

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confidence: 99%

Shear thickening of suspensions of dimeric particles

Mari

2020

Journal of Rheology

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arXiv:2001.08631v2 [cond-mat.soft] 5 Mar 2020 Lerner, Düring, and Wyart, 2012]. The value of the exponent ν is debated [Lerner, Düring, and Wyart, 2012;Gallier et al., 2014a;Mari et al., 2014;Ness and Sun, 2015], the most typical value for spherical particles in the literature being ν = 2 Hermes et al., 2016;Guy et al., 2018]. For long rods, Tapia et al. [2017] measure ν = 1. Shear thickening stems from the fact that φ J , is at a higher value, φ 0 J , for frictionless particles than for frictional ones, at φ 1 J < φ 0 J . Because frictional contacts only exist at large stresses, due to the fact that under small stresses repulsive forces prevent them to form, the suspension has a stress dependent jamming point, φ J (σ), such that η is an increasing function of σ.This scenario is a priori independent of the particle shape. While it has been tested mostly with suspensions of spherical particles, it is expected to be equally valid for suspensions of nonspherical particles, and many such suspensions are known to shear thicken in a qualitatively same way than spherical particles. Cornstarch suspension is the most famous example [Brown and Jaeger, 2009;Fall et al., 2012;Oyarte Gálvez et al., 2017], but suspensions of synthetized particles were also studied [Egres and Wagner, 2005;Brown et al., 2011;Royer et al., 2015;James et al., 2019;Rathee et al., 2019]. Most industrial suspensions known to shear thicken, such as cement paste [Lootens et al., 2004;Papo and Piani, 2004;Feys, Verhoeven, and De Schutter, 2009;Toussaint, Roy, and Jézéquel, 2009;Roussel et al., 2010], suspensions used for mechanical polishing such as fumed silica [Crawford et al., 2012;Amiri, Øye, and Sjöblom, 2012] or quartz powder suspensions [Freundlich and Roder, 1938], fresh paints and coatings [Zupančič, Lapasin, and Žumer, 1997;Khandavalli and Rothstein, 2016], or molten chocolate [Blanco et al., 2019], also contain particles of varied non-spherical shapes. Numerical simulations of suspensions of frictional and repulsive aspherical particles also showed shear thickening [Lorenz et al., 2018].The major difference with spherical particles comes from the different values for φ 0 J and φ 1 J (although other differences exist, e.g. the exponent of the viscosity divergence close to jamming [Tapia et al., 2017]). Indeed, it is known that the jamming point for isotropic random packings generically depends on the shape of the particles [Torquato and Stillinger, 2010;Jiao and Torquato, 2011;Baule and Makse, 2014]. For families of axisymmetric shapes (like axisymmetric ellipsoids, rods, spherocylinders, etc), which can be characterized by one scalar value, the aspect ratio α (the ratio between particle length and width), the behavior is non-monotonic as a function of α. Starting from spheres (α = 1), the jamming volume fraction generally increases up to a maximum reached in the α = 1.2 − 2 range, and then decreases with increasing α for larger aspect ratios [A similar orientation is found in dense suspensions [Egres and Wagner, 2005;Rathee et al., 2019], alt...

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Roughness-dependent tribology effects on discontinuous shear thickening

Cited by 131 publications

References 41 publications

Viewing Earth’s surface as a soft-matter landscape

Viewing Earth’s surface as a soft-matter landscape

Role of particle orientational order during shear thickening in suspensions of colloidal rods

Shear thickening of suspensions of dimeric particles

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