Mobility in granular materials upon cyclic loading

Athani, Shivakumar; Rognon, Pierre

doi:10.1007/s10035-018-0838-6

Cited by 14 publications

(11 citation statements)

References 47 publications

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“…The role of grain inertia on the mobility of objects in granular materials has been further evidenced under cycling loading in [34]. This study showed that an object could sustain an external force larger than F s for a short period of time without moving.…”

Section: Introductionmentioning

confidence: 74%

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Inertial drag in granular media

Athani

Rognon

2019

Phys. Rev. Fluids

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Like in liquids, objects moving in granular materials experience a drag force. We investigate here whether and how the object acceleration affect this drag force. The study is based on simulations of a canonical drag test, which involves vertically uplifting a plate through a granular packing with a prescribed acceleration pattern. Depending on the plate size, plate depth and acceleration pattern, results evidence a rate-independent regime and an inertial regime where the object acceleration strongly enhances the drag force. We introduce an elasto-inertial drag force model that captures the measured drag forces in these two regimes. The model is based on observed physical processes including a gradual, elasto-inertial mobilisation of grains located above the plate. These results and analysis point out fundamental differences between mobility in granular materials upon steady and unsteady loadings. arXiv:1907.05613v1 [cond-mat.soft]

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Section: Introductionmentioning

confidence: 74%

“…There is no interstitial fluid in the pores or long range interaction. Grain translation and rotation are simulated over time using a discrete element method similar to that introduced in [18,34,35]. The plate moving through the packing is made of grains that are similar to the free grains described above.…”

Section: A Granular Materialsmentioning

confidence: 99%

Inertial drag in granular media

Athani

Rognon

2019

Phys. Rev. Fluids

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“…Considering granular solids, their stiffness, and the elastic moduli [31,62,63] have to be considered in the presence of non-affine deformations [63]. For this, overcompression [45,49] and shear [49,60,62,[64][65][66] cyclic loading [66,67] or even thermal cyclic loading [68] were applied. When sheared granular matter starts to flow and (for large enough strain) reaches a steady state, or critical state [69][70][71], the nowadays widely accepted "classical" (I) -rheology [72] holds.…”

Section: A Brief History Of Granular Researchmentioning

confidence: 99%

Un-jamming due to energetic instability: statics to dynamics

2021

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Jamming/un-jamming, the transition between solid- and fluid-like behavior in granular matter, is an ubiquitous phenomenon in need of a sound understanding. As argued here, in addition to the usual un-jamming by vanishing pressure due to a decrease of density, there is also yield (plastic rearrangements and un-jamming that occur) if, e.g., for given pressure, the shear stress becomes too large. Similar to the van der Waals transition between vapor and water, or the critical current in superconductors, we believe that one mechanism causing yield is by the loss of the energy’s convexity (causing irreversible re-arrangements of the micro-structure, either locally or globally). We focus on this mechanism in the context of granular solid hydrodynamics (GSH), generalized for very soft materials, i.e., large elastic deformations, employing it in an over-simplified (bottom-up) fashion by setting as many parameters as possible to constant. Also, we complemented/completed GSH by using various insights/observations from particle simulations and calibrating some of the theoretical parameters—both continuum and particle points of view are reviewed in the context of the research developments during the last few years. Any other energy-based elastic-plastic theory that is properly calibrated (top-down), by experimental or numerical data, would describe granular solids. But only if it would cover granular gas, fluid, and solid states simultaneously (as GSH does) could it follow the system transitions and evolution through all states into un-jammed, possibly dynamic/collisional states—and back to elastically stable ones. We show how the un-jamming dynamics starts off, unfolds, develops, and ends. We follow the system through various deformation modes: transitions, yielding, un-jamming and jamming, both analytically and numerically and bring together the material point continuum model with particle simulations, quantitatively. Graphic abstract

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“…which is proportional to the time for a grain to free fall on a distance d under the action of the gravity. This relaxation time was found to be pivotal to explain the mobility of plates subjected to cyclic or transient loadings [16,17]. Accordingly, we introduce a dimensionless number G, which we refer to as relaxation number, as the ratio of these two times:…”

Section: Gravity Relaxation Timementioning

confidence: 99%

Rate-dependent drag instability in granular materials

Hossain

Rognon

2020

Preprint

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We investigate the conditions leading to large drag force fluctuations in granular materials. The study is based on a set of experimental drag tests, which involve pulling a plate vertically through a cohesionless granular material. In agreement with previous observations, drag force exhibits significant and sudden dropsup to 60%-when the plate is pulled out at low velocities. We further find that this instability vanishes at higher pullout velocities and near the surface. We empirically characterise the frequency and amplitude of these fluctuations and find that these properties are not consistent with a classical stick-slip dynamics. We therefore propose an alternative physical mechanism that can explain these force fluctuations.

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Mobility in granular materials upon cyclic loading

Cited by 14 publications

References 47 publications

Inertial drag in granular media

Inertial drag in granular media

Un-jamming due to energetic instability: statics to dynamics

Rate-dependent drag instability in granular materials

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