Hypervelocity Impact Experiments Research Articles

Simulating impact-induced satellite breakups with a discrete element method

The Discrete Element Method is uniquely suited to modeling the extreme fragmentation typical of impact-induced satellite breakups. In this paper, we introduce a discrete orthotropic material model for simulating carbon fiber reinforced polymers (CFRP). We calibrate and validate the CFRP model with hypervelocity impact experiments performed at Fraunhofer EMI on thin CFRP face sheets. We demonstrate the suitability of the model for simulating spacecraft breakups by comparing simulation results to a ground-based experiment of a 15 x 15 × 15 cm CFRP micro-satellite from literature. Fragment size distributions show excellent agreement between experiment and literature. Comparisons are also made with the NASA breakup model.

Experimental and theoretical study on cavitation of concrete targets penetrated by hypervelocity long rod projectiles

The cavitation phenomenon can seriously decrease the strike performance of military weapons. As military terminal-ballistic activities have turned to hypervelocity attacks, the cavitation effect existing in the hypervelocity penetration deserves more attention. In terms of long-rod hypervelocity penetration into concretes, this study presents an analytical cavity model for the prediction of the cavity diameter based on the two-stage cavitation mechanism and the u-v relationship. The two-stage mechanism involving mushrooming and radial momentum expansion is used to describe the cavitation modes and the penetration parameters for the projectiles used in the analytical model are determined by numerical simulations empirically. Besides, the three modes including rigidity, deformation and erosion are introduced into the cavity model to elucidate the projectile state. Moreover, the hypervelocity impact experiments on the long rods into semi-infinite concrete targets at velocities of 2117 ∼ 3086 m/s are carried out to observe the cavitation effect of concrete targets and for further validating the model through comparing with the experimental cavity profiles, where the cavity profile is quantified with silica gel, and the cavity diameter is found to be more than five times the projectile diameter. The cavitation effect is observed significantly and quantified from the experiment results. The cavity model is compared with the experimental cavity profiles, showing that the model has good applicability.

Vibrational spectroscopic, crystallographic, and microscopic investigation on the Aioun El Atrouss diogenite

AbstractDiogenites are thought to have originated from asteroid 4 Vesta asteroid, and it has been previously shown that they mostly consist of orthopyroxene, chromite, and olivine minerals. In this study, the Aioun El Atrouss (AAT‐1) diogenite was analyzed by vibrational spectroscopic (FT‐IR and micro‐Raman), EDXRF, and XRD techniques. AAT‐001 is mainly composed of pyroxene and with lesser olivine. XRD investigation confirmed magnetite, kamacite, ilmenite, and albite. A troilite‐orthopyroxene intergrowth was revealed by XRF. The olivine composition was estimated to be approximately Fo66 by Raman olivine characteristic doublets. Pyroxenes in AAT‐01 were found to be En80Fs20. Finally, approximate peak shock pressure of more than 86 GPa for AAT‐1 was suggested based on previous hypervelocity impact experiments on olivine.

Simulations of the interaction between fiber bundles/yarns and the energy absorption of the fabric under hypervelocity impact

In this work, the interaction between fiber bundles/yarns and the energy absorption of the multiple fabrics under hypervelocity impact (HVI) are studied by numerical simulation and experiments. In numerical model, an anisotropic elastic-plastic constitutive equation coupled with the Mie-Grüneisen equation of state (EOS) is adopted to describe deviatoric deformation and strongly nonlinear volumetric compression induced by HVI. Considering the internal interactions within fabrics that possess a hierarchical structure and the evolution of impact-induced debris clouds, a meso‑scale model for woven fabrics is developed using the finite element-smoothed particle hydrodynamics (FEM-SPH) adaptive method. The meso‑scale fabric model is validated through HVI experiments, and the simulation results demonstrate excellent agreement with the experimental data. Notably the model reveals an approximately linear increase relationship between the absorbed energy by the fabric and the impact energy of the projectile. Moreover, the meso‑scale fabric model exhibits enhanced predictive capability in modeling the movement and dispersion of debris clouds. Furthermore, the results of the sensitivity analysis of yarn partition indicate that the model is capable of capturing the interactions between fiber bundles/yarns within the fabric during HVI. With increasing impact velocity, the impact time decreases, which reduces the interaction between fabric components and subsequently leading to a decrease in the generated frictional energy.

Simulation of blast propagation and structural effects of accidental hydrogen-air-mixture explosion in a two-stage light-gas gun laboratory for hypervelocity impact experiments

Two-stage light-gas guns allow to accelerate projectiles up to velocities of several kilometers per second to conduct impact experiments. The projectile acceleration is obtained through a mechanism that relies on the expansion of a light gas, such as helium or hydrogen. Hydrogen allows to employ higher projectile velocities and masses than helium, together with lower wear of the launch tube. However, its use requires a thorough assessment of potential risks of explosion. In this work, we present a combined blast and structural numerical analysis to evaluate the effects of hydrogen deflagration as a consequence of accidental leakage scenarios during the operation of a two-stage light-gas gun. As a test case, we study the Large Gun operated at Fraunhofer EMI in Freiburg, Germany. The possible failure of non-structural elements, such as doors and windows, and the subsequent blast propagation into areas adjacent to the room hosting the facility are also accounted for. The simulation procedure presented in this work is scalable to similar and larger facilities for impact research as well as to other contexts involving analogous risks of gas explosions.

V-type Asteroids as the Origin of Mesosiderites

We present the results of a campaign of hypervelocity impact experiments on natural mesosiderite targets, using representative main asteroid belt impact speeds. The objective is to document further the surface evolution of iron-rich asteroids. In contrast with iron meteorites, we demonstrate the fragile behavior of mesosiderite at impact since experiments result in both cratering and catastrophic disruption. The behavior of metal-rich asteroids at impact is thus highly influenced by the original ratio of metal/silicate. A visible to near-infrared spectral analysis shows that the pyroxene silicate signature of impacted mesosiderites, or their ejecta, is fully preserved. Our results thus rule out a mesosiderite hypothesis for the very nature of M/X-type asteroids including (16) Psyche, despite a small fraction of its surface possibly being covered by mesosiderite-like materials. Finally, we address the question of whether mesosiderites and howardite–eucrite–diogenite (HED) meteorites are genetically linked to (4) Vesta or other differentiated asteroids in the main belt based on their spectral similarity.

ALEGRA: Finite element modeling for shock hydrodynamics and multiphysics

ALEGRA is a multiphysics finite-element shock hydrodynamics code, under development at Sandia National Laboratories since 1990. Fully coupled multiphysics capabilities include transient magnetics, magnetohydrodynamics, electromechanics, and radiation transport. ALEGRA is used to study hypervelocity impact, pulsed power devices, and radiation effects. The breadth of physics represented in ALEGRA is outlined here, along with simulated results for a selected hypervelocity impact experiment.

Evaluation of hypervelocity impact of micrometeoroids and orbital debris on next-generation space solar cells

This paper discusses the hypervelocity impacts of micrometeoroids and orbital debris (MMODs) on inverted metamorphic triple-junction (IMM3J) and perovskite solar cells, which are much thinner than conventional triple-junction (3J) solar cells. We experimentally found that IMM3J solar cells can suffer from short-circuit faults due to the hypervelocity impacts of MMODs, unlike conventional 3J cells, and determined the projectile diameters and velocities that could cause them using a model proposed by Burt. No short-circuit mode was identified in perovskite solar cells, but they had open-circuit faults several days after the hypervelocity impact experiment, which are possibly attributed to the decomposition of the perovskite crystal by moisture in the air due to the broken seal.

High Frictional Coated Multi-Layer Ballistic Fabrics for High Velocity and Hypervelocity Impact Protection

Increasing the inter-fiber friction of ballistic fabrics is crucial for improving their impact shielding performance. Shear thickening fluid (STF) impregnation is commonly used to improve inter-fiber friction, but it has several fundamental shortcomings. Polymer coating, with its superior properties, can be an ideal material for increasing the friction coefficient of fabrics. Our study aimed to evaluate the effectiveness of the coating process in enhancing the energy absorption mechanism within and among the fabric layers. Additionally, we investigated the capability of a multi-layer coated fabric system for hypervelocity impact shielding and spall liners. Our findings demonstrated the effectiveness of the coating process in improving the ballistic limit of the fabric system. Coated fabrics showed a 19.6% and 23.4% increase in specific energy absorption compared to pristine fabrics. We conducted hypervelocity impact experiments with impact velocities between 1.9 km/s to 2.1 km/s using a triple bumper system. The front bumper generated a debris cloud, the back bumper comprised the coated fabrics, and the third bumper acted as a witness plate. We compared the area of impact on the witness plate and the penetration area to estimate the efficiency of the coated fabrics. Our results showed that the coated fabrics had a higher area of impact with lower intensity of damage and a decrease in the penetration area compared to pristine fabrics with similar areal densities, indicating excellent impact shielding performance.

The Hypervelocity Impact Behavior and Energy Absorption Evaluation of Fabric

In this work, the mechanical behavior and energy absorption characteristics of flexible fabric under hypervelocity impact (HVI) were investigated. Basalt fabric, ultra-high molecular weight polyethylene (UHMWPE) fabric, and aluminum alloy (Al) plate were chosen to be the sample materials for their excellent mechanical properties and applicative prospect in spacecraft shielding. HVI experiments had been conducted with the help of a two-stage light-gas gun facility, wherein Al projectile with 3.97 mm diameter was launched at velocities in the range 4.1~4.3 km/s. Impact conditions and areal density were kept constant for all targets. The microstructural damage morphology of fiber post-impact was characterized using a scanning electron microscope (SEM). Analysis results show that a brittle fracture occurred for Basalt fiber during HVI. On the contrary, the ductile fractures with large-scale plastic deformation and apparent thermal softening/melting of the material had happened on the UHMWPE fiber when subjected to a projectile impact. According to the HVI shielding performance and microstructural damage analysis results, it can be inferred that ductile fractures and thermal softening/melting of the material were the prevailing energy absorption behaviors of UHMWPE fabric, which leads to absorbing more impact energy than Basalt fabric and eventually, contributes the superior shielding performance.

Momentum transfer from the DART mission kinetic impact on asteroid Dimorphos

The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of the binary asteroid (65803) Didymos, at 23:14 UTC on 26 September 2022 as a planetary defence test1. DART was the first hypervelocity impact experiment on an asteroid at size and velocity scales relevant to planetary defence, intended to validate kinetic impact as a means of asteroid deflection. Here we report a determination of the momentum transferred to an asteroid by kinetic impact. On the basis of the change in the binary orbit period2, we find an instantaneous reduction in Dimorphos’s along-track orbital velocity component of 2.70 ± 0.10 mm s−1, indicating enhanced momentum transfer due to recoil from ejecta streams produced by the impact3,4. For a Dimorphos bulk density range of 1,500 to 3,300 kg m−3, we find that the expected value of the momentum enhancement factor, β, ranges between 2.2 and 4.9, depending on the mass of Dimorphos. If Dimorphos and Didymos are assumed to have equal densities of 2,400 kg m−3, {beta =3.61}_{-0.25}^{+0.19}(1sigma ). These β values indicate that substantially more momentum was transferred to Dimorphos from the escaping impact ejecta than was incident with DART. Therefore, the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos.

Probing shock-induced structural changes in GaSb.

Laser-driven hypervelocity impact experiments were used to study pressure-induced long-term effects on the crystal structure of undoped GaSb. X-ray diffraction and confocal micro-Raman spectra were collected on unshocked and shock-compressed samples, with corresponding pressures ranging between 8 and 23 GPa. GaSb retained bulk crystallinity at 8 GPa but showed localized site disordering, transformed into an amorphous state at 13 GPa, and stayed in that phase until 23 GPa.

A Tracking Algorithm for Debris Cloud Fragments Produced by Different Hypervelocity Impacts through Image Processing

The number of man-made debris is sharply increasing because of more and more human activities being carried out in space, which might seriously threaten the spacecraft performance and even lead to the system instability. In order to guarantee the safe operation of spacecraft, it is necessary to make an in-depth investigation on debris clouds produced by different hypervelocity impact (HVI) experiments and make an accurate damage estimation based on debris characteristics. The interest of this paper is to discuss the main properties of debris clouds that play a central role in damage estimation of the rear wall of Whipple shield protective structure. Those properties include the impact velocity, the evolution velocity, the diameter of the projectile and the incident angle of debris to the rear wall. The purpose of the paper is to track debris fragments and construct a simple trajectory model by employing 2D image processing techniques, and make a damage estimation of debris clouds through different experimental results comparison. More specifically, by using the mean shift algorithm, image noise are greatly eliminated while reserving edges. Then, in terms of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$K$</tex-math></inline-formula> -means algorithm, the overlapping which occurs in some frames is mostly handled and fragments of the underlying images are successfully segmented. Moreover, by utilizing the scale invariant feature transform (SIFT) technique, the image matching is fulfilled, and the trajectory is further established. Finally, based on the established trajectory, the comparison of debris clouds generated by different HVI experiments is provided, through which an accurate damage estimation is formulated. Experimental results demonstrate the effectiveness and validity of the proposed algorithm via image processing.

Plasma production and composition from hypervelocity impacts on solar cell cover glass

Satellites are subjected to detrimental effects from the space environment, including impacts by orbital debris and meteoroids that can cause mechanical or electrical damage. While mechanical damage is well studied, electrical effects resulting from hypervelocity impact (HVI) remain poorly understood. In HVIs, where the projectile speed exceeds the speed of sound in the target material, the impact energy ionizes the material near the surface, creating a plasma that can cause radio frequency emission. This emission is the main source of electrical anomalies in satellites, but the mechanism behind its creation is still unknown. Ground-based experiments have been used to characterize HVI plasma, including the empirical power law relations that describe the impact charge produced as a function of impactor mass and speed. Quantifying these power law relations gives us a better understanding of the species formed in the impact which can eventually lead to plasma evolution models and help us first, understand the mechanism behind radio frequency emission and second, ways to prevent its damage to the satellites.In this paper, we interpret the results of the HVI experiments on solar cell coverglass targets and identify the potential chemical or molecular reactions that form the impact ion species. This is done by looking simultaneously at multiple data sets for different species within the same impact configuration, and using a new technique for quantifying the power law relations for each emitted species. We use time of flight analysis (TOF) to detect the charged particle compositions and determine their initial speeds. The results suggest that the charge production power law is species specific, with different formation mechanisms involved in a single HVI event, some of which are associated with dissociation and some with ionization of a molecule. Our results also show that electrons have different power laws that depend on the spacecraft surface charge. TOF measurements of ions from impact events on solar cell cover glass shows the presence of SiO+ and SiO2− as the dominant species present in plasmas on positively and negatively charged targets, respectively, as well as the formation of FeO+.

Hypervelocity Impact Detection and Location for Stiffened Structures Using a Probabilistic Hyperbola Method.

Hyper-velocity impact (HVI) caused by a collision between orbital debris and spacecraft exists widely in outer space, and it poses a threat to spacecraft. This paper proposes a probabilistic hyperbola method based on Lamb waves analysis to detect and locate the impact in stiffened aluminum (Al) plates. A hybrid model using finite element analysis (FEA) and smoothed particle hydrodynamics (SPH) was developed to gain an insight into characteristics of HVI-induced acoustic emission (AE) and shock wave propagation. In addition, an experimental validation was carried out with a two-stage light gas gun, giving an aluminum projectile a velocity of several kilometers per second. Then a quantitative agreement is obtained between numerical and experimental results, demonstrating the correctness of the hybrid model and facilitating the explanation of received AE signals in experiments. Signal analysis shows that the shock wave quickly converts to a Lamb wave as it propagates from the HVI spot, and the zeroth-order symmetric wave mode (S0) dominates wave signal energy. The S0 wave is dispersive and shows a wide frequency range, with dominant magnitudes below 500 kHz. Finally, the HVI experiment results obtained with a light gas gun showed that the average location error could be less than 1 cm with only four sensors for a 1-square-meter stiffened metal plate.

New Signatures of Bio-Molecular Complexity in the Hypervelocity Impact Ejecta of Icy Moon Analogues.

Impact delivery of prebiotic compounds to the early Earth from an impacting comet is considered to be one of the possible ways by which prebiotic molecules arrived on the Earth. Given the ubiquity of impact features observed on all planetary bodies, bolide impacts may be a common source of organics on other planetary bodies both in our own and other solar systems. Biomolecules such as amino acids have been detected on comets and are known to be synthesized due to impact-induced shock processing. Here we report the results of a set of hypervelocity impact experiments where we shocked icy mixtures of amino acids mimicking the icy surface of planetary bodies with high-speed projectiles using a two-stage light gas gun and analyzed the ejecta material after impact. Electron microscopic observations of the ejecta have shown the presence of macroscale structures with long polypeptide chains revealed from LCMS analysis. These results suggest a pathway in which impact on cometary ices containing building blocks of life can lead to the synthesis of material architectures that could have played a role in the emergence of life on the Earth and which may be applied to other planetary bodies as well.

Hypervelocity impact cratering on 5052-aluminum-alloy targets by flat-head cylindrical impactors of multipartite structure

In the present work, a series of hyper-velocity impact experiments was conducted on targets of aluminum alloy (A5052-H112) block using flat-head cylindrical impactors of plastic/metal/plastic multipartite structure, and the effects of the structure and the impact velocity on the shape of impact craters were investigated. The cylindrical impactors were composed of a front sabot of polycarbonate, an inner metal disk and a rear sabot of high-density polyethylene, polycarbonate or nylon 6. The metal disk was made of 2024-T4 aluminum alloy, Ti-6Al-4 V titanium alloy, or tough-pitch copper. The difference in the material composition together with the impactor's length-to-diameter ratio of 0.5 to 1.2 brought the difference in an averaged density of 1.0 to 2.1 g/cm3. The impact velocity ranged from 5.8 to 7.9 km/s. The cross sections of impact craters obtained were represented hemispherical in the bottom area, because the curvature of the crater bottom wall was regressed well with the radius of a circle arc fitting the bottom wall. Regression equations to reproduce the crater variables of penetration depth, diameter, volume and bottom-wall curvature were found using multiple-regression analysis as the product of powers of the impactor's variables of velocity, averaged density and length. Each equation had high reproducibility for its corresponding crater variable.

Hypervelocity impact behavior of projectile penetration on spacecraft structure: A review

Spacecraft structure has been protected against the space debris impact by using a bumper plate and main plate. When the debris impacts a thin bumper plate at hypervelocity, debris clouds form and the bumper cause the fragment to shatter and reduces the fragment's ability to penetrate the main structure. The size of the hole in the bumper plate indicates the level of damage to the primary structure. The projectile material's mass in the cloud creates a considerable ballistic threat to the main structure. Various stages of the penetration process have been discussed. The empirical and approximate theoretical formulations created to characterize many features of hypervelocity impact when the projectile and some of the target materials undergo enormous plastic deformation, breakdown, melting, or vaporization are reviewed. For the numerical simulation of hypervelocity impact of space debris on spacecraft structure, Johnson-Cook material and failure model along with Mie-Gruneisen equation of state are used. For the hypervelocity impact experiment, a two-stage light gas gun is mostly preferred.

Modeling Early Clustering of Impact-induced Ejecta Particles Based on Laboratory and Numerical Experiments

Abstract A projectile impact onto a granular target produces an ejecta curtain with heterogeneous material distribution. Understanding how the heterogeneous pattern forms is potentially important for understanding how crater rays form. Previous studies predicted that the pattern formation is induced by inelastic collisions of ejecta particles in early stages of crater formation and terminated by the ejecta’s expanding motion. In this study, we test this prediction based on a hypervelocity impact experiment together with N-body simulations where the trajectories of inelastically colliding granular particles are calculated. Our laboratory experiment suggests that pattern formation is already completed on a timescale comparable to the geometrical expansion of the ejecta curtain, which is ∼10 μs in our experiment. Our simulations confirm the previous prediction that the heterogeneous pattern grows through initial inelastic collisions of particle clusters and subsequent geometric expansion with no further cluster collisions. Furthermore, to better understand the two-stage evolution of the mesh pattern, we construct a simple analytical model that assumes perfect coalescence of particle clusters upon collision. The model shows that the pattern formation is completed on the timescale of the system’s expansion independently of the initial conditions. The model also reproduces the final size of the clusters observed in our simulations as a function of the initial conditions. It is known that particles in the target are ejected at lower speeds with increased distance to the impact point. The difference in the ejection speed of the particles may result in the evolution of the mesh pattern into rays.

Effects of electron beam irradiation on hypervelocity impact behavior of carbon fiber reinforced plastic plates

The effects of electron beam irradiation were examined on perforation holes and fragments from quasi-isotropic carbon fiber reinforced plastic plates (CFRP plates). CFRP plates with a total dose up to 60 MGy of electron beam irradiation were prepared for hypervelocity impact experiments. The perforation holes of CFRP plates in the hypervelocity impact experiments were decreased with electron beam irradiation when aluminum alloy spherical projectiles (2017-T4) of diameter of 1 mm struck at an impact velocity of 5 km/s. However, a slight reduction in the size of the perforation hole was observed at 2 km/s. Fragments ejected from CFRP plates were examined after collection from the impact side and rear side of the targets. The cumulative number distributions of fragment length and aspect ratio were compared among specimens with different total doses.