Dynamics of shear bands in a dense granular material forced by a slowly moving rigid body

Hamm, Eugenio; Tapia, Franco; Melo, Francisco

doi:10.1103/physreve.84.041304

Cited by 27 publications

(41 citation statements)

References 20 publications

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“…It is noted that in the case without vibrations (Fig 4a), the motion of the tip of the intruder induces grain displacements along a curve which connects the tip of the intruder to the free surface. This curve reflects the path of force chains that develop in the granular media, as previously reported by Hamm et al [9]. In presence of mechanical vibrations, the flow field of the granular material around the finger is modified (Fig 4b).…”

Section: Resultssupporting

confidence: 75%

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Low-resistive vibratory penetration in granular media

2017

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Non-cohesive materials such as sand, dry snow or cereals are encountered in various common circumstances, from everyday situations to industry. The process of digging into these materials remains a challenge to most animals and machines. Within the animal kingdom, different strategies are employed to overcome this issue, including excavation methods used by ants, the two-anchor strategy employed by soft burrowers such as razor-clams, and undulatory motions exhibited by sandfish lizards. Despite the development of technology to mimic these techniques in diggers and robots, the limitations of animals and machines may differ, and mimicry of natural processes is not necessarily the most efficient technological strategy. This study presents evidence that the resisting force for the penetration of an intruder into a dry granular media can be reduced by one order of magnitude with small amplitude (A ≃ 10 μm) and low frequency (f = 50 − 200 Hz) mechanical vibrations. This observed result is attributed to the local fluidization of the granular bed which induces the rupture of force chains. The drop in resistive force on entering dry granular materials may be relevant in technological development in order to increase the efficiency of diggers and robots.

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Section: Resultssupporting

confidence: 75%

“…Recording the motion of grains from the side view and using image correlation techniques similar to Hamm et al [9], it was possible to infer the mean velocity of field of grains induced by intruder motion. Fig 4a and 4b present results for both the vibrating and non-vibrating scenarios.…”

Section: Resultsmentioning

confidence: 99%

Low-resistive vibratory penetration in granular media

2017

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“…In most cases, these forces do not depend significantly on velocity [6,9,10,16] but increase with depth [9][10][11][12][13]. Depending on the shape of objects, the force variation with depth may be linear or not [17][18][19]. More recently, some possible deformation of objects moving into granular matter have been considered for addressing the problem of the root growth in soil [20].…”

Section: Introductionmentioning

confidence: 99%

Buckling of a rod penetrating into granular media

Seguin

Gondret

2018

Phys. Rev. E

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We investigate experimentally the possible buckling of a thin rod when penetrating downwards into a granular packing. When its bottom end reaches a specific depth, the rod may start buckling provided that the embrace is not enough to stop that phenomenon. The critical rod depth z_{c} at buckling is observed to scale with the rod length L either as 1/L or 1/L^{2}. These two scalings are shown to arise from the two resistant force terms that come into play during the rod penetration: a pressure force at the bottom of the rod that increases linearly with depth and a frictional force on the rod side that increases quadratically with depth. At the buckling point, the destabilizing force corresponds to the expected value given from conventional Euler's critical load for a rod bottom end considered as fixed in the granular clutch. Finally, we draw a buckling-nonbuckling phase diagram in a parameter space given by the rod aspect ratio and a rod-to-grain stress ratio.

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“…Plate drag is a particular example of a more general class of GM interactions called localized forcing that are relevant in the locomotion of organisms or robots [1][2][3]. Localized forcing of GM consists of a localized boundary that is displaced or rotated through an extended granular medium [4][5][6][7][8][9][10][11][12][13][14].…”

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confidence: 99%

“…However many interactions with GM are localized and thus detailed understanding of the principles of localized forcing are needed. Recent studies of localized forcing, such as horizontal drag [15], vertical penetration [12,[16][17][18], rotation of a plate within granular media [19], or impact experiments [20,21] have highlighted the important role the initial volume fraction φ of the material plays in force and flow dynamics. Granular material may compact (decrease in occupied volume) or dilate (expand in occupied volume) under an imposed shear depending on the initial φ [22].…”

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confidence: 99%

Force and flow at the onset of drag in plowed granular media

2014

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We study the transient drag force FD on a localized intruder in a granular medium composed of spherical glass particles. A flat plate is translated horizontally from rest through the granular medium to observe how FD varies as a function of the medium's initial volume fraction, ϕ. The force response of the granular material differs above and below the granular critical state, ϕc, the volume fraction which corresponds to the onset of grain dilatancy. For ϕ<ϕc FD increases monotonically with displacement and is independent of drag velocity for the range of velocities examined (<10 cm/s). For ϕ>ϕc, FD rapidly rises to a maximum and then decreases over further displacement. The maximum force for ϕ>ϕc increases with increasing drag velocity. In quasi-two-dimensional drag experiments, we use granular particle image velocimetry (PIV) to measure time resolved strain fields associated with the horizontal motion of a plate started from rest. PIV experiments show that the maxima in FD for ϕ>ϕc are associated with maxima in the spatially averaged shear strain field. For ϕ>ϕc the shear strain occurs in a narrow region in front of the plate, a shear band. For ϕ<ϕc the shear strain is not localized, the shear band fluctuates in space and time, and the average shear increases monotonically with displacement. Laser speckle measurements made at the granular surface ahead of the plate reveal that for ϕ<ϕc particles are in motion far from the intruder and shearing region. For ϕ>ϕc, surface particles move only during the formation of the shear band, coincident with the maxima in FD, after which the particles remain immobile until the sheared region reaches the measurement region.

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Dynamics of shear bands in a dense granular material forced by a slowly moving rigid body

Cited by 27 publications

References 20 publications

Low-resistive vibratory penetration in granular media

Low-resistive vibratory penetration in granular media

Buckling of a rod penetrating into granular media

Force and flow at the onset of drag in plowed granular media

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