Improvements to the ɛ-α porous compaction model for simulating impacts into high-porosity solar system objects

Collins, G. S.; Melosh, H. J.; Wünnemann, K.

doi:10.1016/j.ijimpeng.2010.10.013

Cited by 147 publications

(168 citation statements)

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“…pressure or volume strain), which is often referred to as the compaction (crush) curve or compaction function. For further details on different compaction models, see Hermann (1969), Kerley (1992), Wünnemann et al (2006), Jutzi et al (2008) and Collins et al (2011).…”

Section: Equations Of Statementioning

confidence: 99%

Numerical Modelling of Impact Processes

Collins¹,

Wünnemann²,

Artemieva³

et al. 2012

Impact Cratering

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Numerical modelling is now a well-established and important component of impact research. When used to complement small-scale impact experiments, it provides a powerful tool for exposing the physical processes in a cratering event and for investigating the effect of individual physical parameters that are not otherwise under the experimenter's control. Moreover, once adequately validated against small-scale laboratory experiments, numerical models allow us to simulate impacts much larger and more energetic than those that can be studied experimentally.The first numerical impact simulation was published in 1961 by R.L. Bjork (Fig. 17.1). That calculation of the Meteor Crater impact simulated only the first 60 ms of the collision and did not account for gravity or the strength of the target rocks (Bjork, 1961). Nevertheless, that simulation, and those that followed in the next decades, provided great insight into the physics of hypervelocity impact, including the formation and attenuation of the detached shock wave, the fate of the impactor, and the scaling of crater dimensions (e.g. Ahrens and O'Keefe, 1977;Orphal, 1977;O'Keefe and Ahrens, 1993).Nearly half a century on, and thanks to advances in numerical impact models and much improved computational resources, numerical models that include gravity and complex material models are used routinely to simulate large terrestrial impacts, aiding interpretation of geological and geophysical observations and quantifying the energy of the impact and impact-related consequences. For example, several numerical impact models of the Chicxulub impact have been performed and compared with observational data to constrain the impact energy, the fate of the projectile, the volume of climate forcing gases released into the atmosphere, the transport and re-entry of ejected material and the regional seismicity (e.g.

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Section: Equations Of Statementioning

confidence: 99%

Numerical Modelling of Impact Processes

Collins¹,

Wünnemann²,

Artemieva³

et al. 2012

Impact Cratering

View full text Add to dashboard Cite

show abstract

“…Our model for porous solar system material is composed of: the improved ε-α porosity model [3] to represent compaction of void space (Table 1); a Mie-Gruneisen EoS for fused silica (grain density, ρ = 2.2 g/cm 3 , speed of sound at P = 0, C s0 = 5.124 km/s, Gruneisen parameter, Γ = 0.9 and bulk modulus calculated as A = ρ s C 2 s0 = 57.76 GPa [4]) to represent the behaviour of the solid part of the matrix; and a Drucker-Prager strength model that defines the yield strength of the bulk material, Y , as…”

Section: Materials Model For Porous Materialsmentioning

confidence: 99%

“…We investigate cratering in granular materials of different porosities impacted under different gravitational conditions in order to develop a general material model for bodies in the solar system of a wide range of porosities. Impact simulations were performed using iSALE-2D hydrocode, which includes an efficient porous compaction model, the ε-α model [2,3]. We compare impact simulations with laboratory impact experiments [1] to test our model for porous solar system material.…”

Section: Introductionmentioning

confidence: 99%

High-velocity impacts in porous solar system materials

Miljković¹,

Collins²,

Chapman³

et al. 2012

AIP Conference Proceedings

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High-velocity impacts on planetary surfaces are common events in the solar system. The consequences of such impacts depend, in part, on the properties of the target solar system body, such as surface strength, porosity and gravity. Bodies in the solar system exhibit a range of material properties, hence it is difficult to specify a general material model. Experimental investigations of impacts onto solar system surfaces often use sand as an analogue material and hydrocode simulations of impact often assume a sand-like equation of state (EoS) and strength model, which is valid only for a limited range of porosities. To simulate impact on smaller bodies in the solar system, such as asteroids, comets or smaller planetary satellites, requires a more appropriate material model. We compare iSALE-2D hydrocode simulations of impacts in porous granular materials with results from laboratory impact experiments made by [1] to test and refine a general-purpose material model applicable for a wide range of porous materials in the solar system.

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“…Because these events span over a large number of magnitudes both spatially, from cohesive forces on an atomic level to kilometre sized bodies, as well as temporally, where supersonic waves and the long-term fate of ejected material have to be considered, numerical codes have always to be a compromise between accuracy and usability. Therefore, in many impact simulations the interior of rubble pile asteroids are treated as homogeneous, monolithic material, and the existence of internal voids and porosity is incorporated using an adapted material model (e. g. Collins et al 2011). While this approach is able to reproduce the bulk properties of asteroids, it does not tell us how the rubble pile interior might be rearranged during an impact event.…”

Section: Modelling Of Hyper-velocity Impactsmentioning

confidence: 99%

Hyper-Velocity Impacts on Rubble Pile Asteroids

Deller¹

2017

Springer Theses

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SummaryMost asteroids in the size range of approximately 100 m to 100 km are rubble piles, aggregates of rocky material held together mainly by gravitational forces, and only weak cohesion. They contain high macroporosities, indicating a large amount of void space in their interiors. How these voids are distributed is not yet known, as in-situ measurements are still outstanding.In this work, a model to create rubble pile asteroid simulants for use in SPH impact simulations is presented. Rubble pile asteroids are modelled as gravitational re-aggregating remnant fragments of a catastrophically disrupted parent body, which are represented by spherical pebbles. It is shown that this approach allows to explicitly follow the internal restructuring of rubble pile asteroids during impact events, while preserving the expected properties of the bulk asteroid as known from observations and experiments. The bulk behaviour of asteroid simulants, as characterized by the stability against disruption and fragment size distribution, follows the expected behaviour and is not sensitive to the exact distribution of voids in the interior structure, but rather to the void fraction as the amount of consolidated void space in between the constituent fragment pebbles. No exact a priory knowledge of the fragment size distribution inside the body is therefore needed to use this model in impact simulations.Modelling the behaviour of the large-scale rubble pile constituents during impact events is used as a tool to infer the internal structure of asteroids by linking surface features like hills or pits to the creation of sub-catastrophic craters.In this work, the small rubble pile asteroid (2867) Šteins is analysed. The flyby of the Rosetta spacecraft at Šteins has revealed several interesting features: the large crater Diamond close to the southern pole, a hill like feature almost opposite to the crater, and a catena of crater pits extending radially from the rim of the crater.A possible link between these two structures and the cratering event is investigated in a series of impact simulations varying the interior of a plausible shape of Šteins prior to the event that formed crater Diamond. A connection between the cratering event and the hill is shown to be highly unlikely. Therefore, the hill is most likely a remnant of the formation of Šteins. Its size therefore helps to infer the initial size distribution of fragments forming the asteroid.The formation of a fracture radially from the crater can be observed for rubble pile simulants with highly collimated voids. This fracture could plausibly form the catena of pits observed on Šteins. This can therefore serve as a link between observable surface features and Šteins internal structure. The interior of Šteins is most likely an aggregate of fragments that themselves are only lightly fractured, and large void spaces might be found inside the asteroid. As Šteins seems to be a good example of a YORPoid, an asteroid that has been evolved to a top-like shape by radiative forces due to the YORP ...

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Improvements to the ɛ-α porous compaction model for simulating impacts into high-porosity solar system objects

Cited by 147 publications

References 8 publications

Numerical Modelling of Impact Processes

Numerical Modelling of Impact Processes

High-velocity impacts in porous solar system materials

Hyper-Velocity Impacts on Rubble Pile Asteroids

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