Impact experiments on highly porous targets: Cavity morphology and disruption thresholds in the strength regime

Okamoto, Takaya; Nakamura, Akiko; Hasegawa, Susumu

doi:10.1016/j.pss.2014.08.008

Cited by 6 publications

(12 citation statements)

References 34 publications

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“…Laboratory high-velocity impact experiments, using millimeter-to-centimeter size projectiles to study cratering in the strength regime, were performed for various targets with porosities ranging from 0% to more than 90%. The morphology and dimensions, i.e., diameter and depth, were studied for weak cemented basalt targets (Housen, 1992), sandperlite-fly ash mixture targets (Housen and Holsapple, 2003), sintered glass bead targets (Love et al, 1993;Michikami et al, 2007;Hiraoka et al, 2008;Okamoto et al, 2015; Okamoto and Nakamura 2017), cement mortar targets (Michikami et al, 2017), gypsum targets Okamoto and Nakamura, 2017), and natural porous rocks (Baldwin, et al, 2007;Kenkmann, et al, 2011;Suzuki et al, 2012;Poelchau, M. H., 2014;Flynn, et al, 2015;Okamoto and Nakamura, 2017). Table 1 summarizes the target density, porosity, strength, impact velocity, and projectile material and diameter of these experiments.…”

Section: Targets In the Strength Regimementioning

confidence: 99%

Section: High-velocity Impact Cratering Experiments Of Porous Targets...mentioning

confidence: 99%

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Impact cratering on porous targets in the strength regime

Nakamura

2017

Planetary and Space Science

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Cratering on small bodies is crucial for the collision cascade and also contributes to the ejection of dust particles into interplanetary space. A crater cavity forms against the mechanical strength of the surface, gravitational acceleration, or both. The formation of moderately sized craters that are sufficiently larger than the thickness of the regolith on small bodies, in which mechanical strength plays the dominant role rather than gravitational acceleration, is in the strength regime. The formation of microcraters on blocks on the surface is also within the strength regime. On the other hand, the formation of a crater of a size comparable to the thickness of the regolith is affected by both gravitational acceleration and cohesion between regolith particles.In this short review, we compile data from the literature pertaining to impact cratering experiments on porous targets, and summarize the ratio of spall diameter to pit diameter, the depth, diameter, and volume of the crater cavity, and the ratio of depth to diameter. Among targets with various porosities studied in the laboratory to date, based on conventional scaling laws (Holsapple and Schmidt, J. Geophys. Res., 87, 1849-1870

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Section: Targets In the Strength Regimementioning

confidence: 99%

Section: High-velocity Impact Cratering Experiments Of Porous Targets...mentioning

confidence: 99%

Impact cratering on porous targets in the strength regime

Nakamura

2017

Planetary and Space Science

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“…To examine the outcome of collisional disruption of targets with high porosity, targets formed of hollow-glass beads with bulk porosity of 87% and 94% have been impacted at velocities between 1.8 and 7 km s -1 (Okamoto et al, 2015). The specific energy required for disruption was as large as several kJ/kg, which is much larger than that required for basalt targets.…”

Section: Introductionmentioning

confidence: 99%

“…The filamentous framework of the dust aggregate may be simulated by a very thin mesh wall surrounding the void. The hollow glass bead used in a previous study (Okamoto et al, 2015) has thin shell with a thickness of 0.95 m. Although the shell of the hollow bead is not a mesh structure, a sintered hollow glass bead target may mimic the mechanical and impact response of primitive highly porous bodies formed by the accumulation of porous dust aggregates, especially thermally evolved icy bodies with enhanced bonding between icy dust grains of ~1 m size.…”

Section: Introductionmentioning

confidence: 99%

Collisional disruption of highly porous targets in the strength regime: Effects of mixture

Murakami

Nakamura

Yokoyama

et al. 2020

Planetary and Space Science

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Highly porous small bodies are thought to have been ubiquitous in the early solar system. Therefore, it is essential to understand the collision process of highly porous objects when considering the collisional evolution of primitive small bodies in the solar system. To date, impact disruption experiments have been conducted using high-porosity targets made of ice, pumice, gypsum, and glass, and numerical simulations of impact fracture of porous bodies have also been conducted. However, a variety of internal structures of high-porosity bodies are possible. Therefore, laboratory experiments and numerical simulations in the wide parameter space are necessary.In this study, high-porosity targets of sintered hollow glass beads and targets made by mixing perlite with hollow beads were used in a collision disruption experiment to investigate the effects of the mixture on collisional destruction of high-porosity bodies.Among the targets prepared under the same sintering conditions, it was found that the targets with more impurities tend to have lower compressive strength and lower resistance against impact disruption. Further, destruction of the mixture targets required more impact energy density than would have been expected from compressive strength. It is likely that the perlite grains in the target matrix inhibit crack growth through the glass framework. The mass fraction of the largest fragment collapsed to a single function of a scaling parameter of energy density in the strength regime ( ) when assuming ratios of tensile strength to compressive strength based on a relationship obtained for ice-silicate mixtures. However, the dependence on is much larger than that shown for porous targets with different internal microstructures from the targets in this study. The depth of the deep cavity specific to the high-porosity target was well represented by a dimensionless parameter using the compressive strength of both the pure glass and mixture targets. The empirical relationship of cavity depth was shown to hold for various targets used in previous studies irrespective of the internal microstructure of the targets.

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“…Although laboratory experiments have provided much insight into cratering phenomena in terms of qualitative descriptions or semi-analytic expressions, including bulb-shaped tracks on porous targets 13 , crater-ray formations of impact ejecta 14 , and low-speed penetration resistance 15 – 17 , coupled with granular flow and compaction 18 , 19 , we still do not fully understand the cratering process, partially due to the difficulties in experimentally tracing the motions of target particles. Such limitation can be overcome through numerical simulations, e.g., by using the Soft-Sphere Discrete Element Method developed by Cundall & Strack 10 , 20 , which consequently complements our understanding of the excavation stage 12 , 21 , and the amount of ejected mass 22 , 23 .…”

Section: Introductionmentioning

confidence: 99%

Asteroid surface impact sampling: dependence of the cavity morphology and collected mass on projectile shape

Cheng

Baoyin

2017

Sci Rep

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In-situ exploration and remote thermal infrared observation revealed that a large fraction of Solar System small bodies should be covered with granular regolith. The complex and varied geology of the regolith layer may preserve the historical records of the surface modification and topographic evolution experienced by asteroids, especially cratering processes, in which the projectile shape plays a crucial role. Regarding the impact sampling scheme, the projectile-shape dependence of both the cavity morphology and the collected mass remains to be explored. This paper studies the process of the low-speed impact sampling on granular regolith using projectiles of different shapes. The results demonstrate that the projectile shape significantly influences the excavation stage, forming cavities with different morphologies, i.e., cone-shaped, bowl-shaped and U-shaped. We further indicate that the different velocity distributions of the ejecta curtains due to the various projectile shapes result in various amounts of collected mass in sampler canister, regarding which the 60° conical projectile exhibits preferable performance for impact sampling scheme. The results presented in this article are expected to reveal the dependence of the excavation process on projectile shape under micro gravity and provide further information on the optimal designs of impact sampling devices for future sample-return space missions.

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Impact experiments on highly porous targets: Cavity morphology and disruption thresholds in the strength regime

Cited by 6 publications

References 34 publications

Impact cratering on porous targets in the strength regime

Impact cratering on porous targets in the strength regime

Collisional disruption of highly porous targets in the strength regime: Effects of mixture

Asteroid surface impact sampling: dependence of the cavity morphology and collected mass on projectile shape

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