Projectile-shape dependence of impact craters in loose granular media

Newhall, Katherine A.; Durian, Douglas J.

doi:10.1103/physreve.68.060301

Cited by 72 publications

(62 citation statements)

References 7 publications

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“…Figure 1(a) illustrates the details of the experimental setup. In all experiments, a dry noncohesive granular medium, sand (grain density ρ g = 2.1 g/cm 3 and grain diameter D g ∼ 0.3mm) or couscous (ρ g = 1.2 g/cm 3 and D g ∼ 2mm), is used as the impact target. The target is held within a large rectangular container (38 cm width by 49 cm length by 20 cm depth); this size is large enough to minimize boundary effects to the intruder's trajectory [6,24] that is filled by grains, is held approximately constant, as acquired by pouring grains into the container and tapping.…”

Section: Pacs Numbers: I Introductionmentioning

confidence: 99%

“…There has been significant effort to understand the way by which momentum is transferred to granular media, beginning over a century ago [1]. Studies of penetration into dry granular media have expanded significantly to focus on crater formation [2][3][4][5][6][7][8] and proposed governing force laws [9][10][11][12][13]. Additionally, a complete comprehension of granular impact has a natural connection to navigation on grainy surfaces [14,15], geomorphology, and astrophysical craters [16][17][18][19].…”

Section: Pacs Numbers: I Introductionmentioning

confidence: 99%

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Collisional model of energy dissipation in three-dimensional granular impact

Bester

Behringer

2017

Phys. Rev. E

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We study the dynamic process occurring when a granular assembly is displaced by a solid impactor. The momentum transfer from the impactor to the target is shown to occur through sporadic, normal collisions of high force carrying grains at the intruder surface. We therefore describe the stopping force of the impact through a collisional based model. To verify the model in impact experiments, we determine the forces acting on an intruder decelerating through a dense granular medium using high-speed imaging of its trajectory. By varying the intruder shape and granular target, intrudergrain interactions are inferred from the consequent path. As a result, we connect the drag to the effect of intruder shape and grain density based on a proposed collisional model.

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Section: Pacs Numbers: I Introductionmentioning

confidence: 99%

Section: Pacs Numbers: I Introductionmentioning

confidence: 99%

Collisional model of energy dissipation in three-dimensional granular impact

Bester

Behringer

2017

Phys. Rev. E

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“…In a fashion similar to that of de Bruyn and Walsh [19], upon inspection of the slopes α 1 as a function of φ, we can deduce the critical value φ c = 64.5%, very close to the random close packing fraction φ rcp ≈ 64%. Using the correction factor (1 − φ/φ c ), we show that the data can be approximately described by the scaling δ ∼ H 1/3 observed previously [6,17,19], as shown in Fig. 2(c), the effects of air notwithstanding.…”

Section: A Monodisperse Materialsmentioning

confidence: 76%

“…For shallow penetrations, where δ = O(D 0 ) [see Fig. 1(a)], the works of Durian and co-workers [3,6,17,18] provide authoritative sources of the various scalings for this key measurement and can generally be summarized in terms of the impactor density, diameter, and fall height (ρ 0 , D 0 , and h, respectively) as…”

Section: Introductionmentioning

confidence: 99%

Penetration in bimodal, polydisperse granular material

2016

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We investigate the impact penetration of spheres into granular media which are compositions of two discrete size ranges, thus creating a polydisperse bimodal material. We examine the penetration depth as a function of the composition (volume fractions of the respective sizes) and impact speed. Penetration depths were found to vary between δ = 0.5D 0 and δ = 7D 0 , which, for mono-modal media only, could be correlated in terms of the total drop height, H = h + δ, as in previous studies, by incorporating correction factors for the packing fraction. Bimodal data can only be collapsed by deriving a critical packing fraction for each mass fraction. The data for the mixed grains exhibit a surprising lubricating effect, which was most significant when the finest grains , with a size ratio, = d l /d s , larger than 3 and mass fractions over 25%, despite the increased packing fraction. We postulate that the small grains get between the large grains and reduce their intergrain friction, only when their mass fraction is sufficiently large to prevent them from simply rattling in the voids between the large particles. This is supported by our experimental observations of the largest lubrication effect produced by adding small glass beads to a bed of large sand particles with rough surfaces.

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“…Related phenomena occur in industrial settings, for instance in mixers or other machinery, where a blade can impact a material. There is a large relevant literature, of which we note a number of references, including the references which they cite [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] During an impact, a number of coupled processes are at work, and most of these are only partially understood. At the largest scale, the granular material exerts a force on the intruder, bringing it to rest.…”

Section: Introductionmentioning

confidence: 99%

Granular Impact

Clark¹,

Petersen²,

Kondic³

et al. 2015

Rapid Penetration Into Granular Media

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This work summarizes a series of studies on two-dimensional granular impact, where an intruding object strikes a granular material at high speed. Many previous studies on granular impact have used a macroscopic force law, which is dominated by an inertial drag term proportional to the intruder velocity squared. The primary focus here is on the microscopic force response of the granular material, and how the grain-scale effects give rise to this inertial drag term. We show that the inertial drag arises from intermittent collisions with force-chain-like structures. We construct a simple collisional model to explain the inertial drag, as well as off-axis instability and rotations. Finally, we show how the granular response changes when the intruder speed approaches d/tc, leading to a failure of the inertial drag description in this regime. Here, d is the mean particle diameter and tc the characteristic momentum-transfer time between two grains.

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Projectile-shape dependence of impact craters in loose granular media

Cited by 72 publications

References 7 publications

Collisional model of energy dissipation in three-dimensional granular impact

Collisional model of energy dissipation in three-dimensional granular impact

Penetration in bimodal, polydisperse granular material

Granular Impact

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