Hypervelocity impacts into graphite

Latunde-Dada, Seyi; Cheesman, C; Day, Donald R; Harrison, W. N.; Price, Sharon S.

doi:10.1088/1742-6596/286/1/012042

Cited by 8 publications

(10 citation statements)

References 6 publications

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“…For impacts of steel spheres onto graphite targets, Latunde-Dada et al [20] have demonstrated a good correlation between the measured crater volume and an approximated conical one using the depth and the diameter as characteristic dimensions. Regarding Fig.…”

Section: Crater Volumementioning

confidence: 97%

“…In Ref. [20], Latunde-Dada et al proposed no correlation between impact speed and crater volume. However, their data are plotted in Fig.…”

Section: Crater Volumementioning

confidence: 99%

“…Concerning composites, studies have already been conducted [17,18], but it appears there is a lack of knowledge about damaging and cratering processes of elementary components such as graphite matrix or fibers. Experimental results have been published giving crater dimensions in porous graphite for a variety of projectile materials and velocities [19,20]. The present authors have attempted to compute numerical models into hydrocodes to reproduce experimental results [21].…”

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confidence: 99%

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Penetration and cratering experiments of graphite by 0.5-mm diameter steel spheres at various impact velocities

Seisson

Hebert

Hallo

et al. 2014

International Journal of Impact Engineering

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. Cratering experiments have been conducted with 0.5-mm diameter AISI 52100 steel spherical projectiles and 30-mm diameter, 15-mm long graphite targets. The latter were made of a commercial grade of polycrystalline and porous graphite named EDM3 whose behavior is known as macroscopically isotropic. A two-stage light-gas gun launched the steel projectiles at velocities between 1.1 and 4.5 km s À1. In most cases, post-mortem tomographies revealed that the projectile was trapped, fragmented or not, inside the target. It showed that the apparent crater size and depth increase with the impact velocity. This is also the case of the crater volume which appears to follow a power law significantly different from those constructed in previous works for similar impact conditions and materials. Meanwhile, the projectile depth of penetration starts to decrease at velocities beyond 2.2 km s À1. This is firstly because of its plastic deformation and then, beyond 3.2 km s À1, because of its fragmentation. In addition to these three regimes of penetration behavior already described by a few authors, we suggest a fourth regime in which the projectile melting plays a significant role at velocities above 4.1 km s À1. A discussion of these four regimes is provided and indicates that each phenomenon may account for the local evolution of the depth of penetration.

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Section: Crater Volumementioning

confidence: 97%

“…In Ref. [20], Latunde-Dada et al proposed no correlation between impact speed and crater volume. However, their data are plotted in Fig.…”

Section: Crater Volumementioning

confidence: 99%

mentioning

confidence: 99%

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Penetration and cratering experiments of graphite by 0.5-mm diameter steel spheres at various impact velocities

Seisson

Hebert

Hallo

et al. 2014

International Journal of Impact Engineering

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“…For instance, the behavior of composites with carbon components has been examined under HVI [11,12]. Experimental results have been recently published which give crater dimensions in porous graphite for a variety of projectile materials and velocities [13]. However, in order to improve the predictive capabilities of hydrodynamic simulations for such materials, it appears that modeling porous graphite is needed.…”

Section: Introductionmentioning

confidence: 99%

Dynamic cratering of graphite: Experimental results and simulations

Seisson

Hebert

Bertron

et al. 2014

International Journal of Impact Engineering

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. b s t r a c tThe cratering process in brittle materials under hypervelocity impact (HVI) is of major relevance for debris shielding in spacecraft or high-power laser applications. Amongst other materials, carbon is of particular interest since it is widely used as elementary component in composite materials. In this paper we study a porous polycrystalline graphite under HVI and laser impact, both leading to strong debris ejection and cratering. First, we report new experimental data for normal impacts at 4100 and 4200 m s À1 of a 500-mm-diameter steel sphere on a thick sample of graphite. In a second step, dynamic loadings have been performed with a high-power nanosecond laser facility. High-resolution X-ray tomographies and observations with a scanning electron microscope have been performed in order to visualize the crater shape and the subsurface cracks. These two post-mortem diagnostics also provide evidence that, in the case of HVI tests, the fragmented steel sphere was buried into the graphite target below the crater surface. The current study aims to propose an interpretation of the results, including projectile trapping. In spite of their efficiency to capture overall trends in crater size and shape, semi-empirical scaling laws do not usually predict these phenomena. Hence, to offer better insight into the processes leading to this observation, the need for a computational damage model is argued. After discussing energy partitioning in order to identify the dominant physical mechanisms occurring in our experiments, we propose a simple damage model for porous and brittle materials. Compaction and fracture phenomena are included in the model. A failure criterion relying on Weibull theory is used to relate material tensile strength to deformation rate and damage. These constitutive relations have been implemented in an Eulerian hydrocode in order to compute numerical simulations and confront them with experiments. In this paper, we propose a simple fitting procedure of the unknown Weibull parameters based on HVI results. Good agreement is found with experimental observations of crater shapes and dimensions, as well as debris velocity. The projectile inclusion below the crater is also reproduced by the model and a mechanism is proposed for the trapping process. At least two sets of Weibull parameters can be used to match the results. Finally, we show that laser experiment simulations may discriminate in favor of one set of parameters.

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“…These are simple power laws which, with the aid of experimental data, relate the crater dimensions to the governing parameters of the cratering process. In addition, there have also been a variety of studies into oblique planetary impacts two of which are reported in [4,5] In [6], the 2/3 power law, which has been verified for a variety of ductile materials, was derived by correlating the projectile energy to the volume of the crater formed. This states that the crater depth p and diameter d c normalized to the projectile diameter d p scale as the impact velocity v raised to the power of 2/3.…”

Section: Introductionmentioning

confidence: 99%