Showing papers on "Projectile published in 2021"

Benchmark Experiment to Prove the Role of Projectile Excited States Upon the Ion Stopping in Plasmas

Abstract: We report on a precision energy loss measurement and theoretical investigation of $100\text{ }\text{ }\mathrm{keV}/u$ helium ions in a hydrogen-discharge plasma. Collision processes of helium ions with protons, free electrons, and hydrogen atoms are ideally suited for benchmarking plasma stopping-power models. Energy loss results of our experiments are significantly higher than the predictions of traditional effective charge models. We obtained good agreement with our data by solving rate equations, where in addition to the ground state, also excited electronic configurations were considered for the projectile ions. Hence, we demonstrate that excited projectile states, resulting from collisions, leading to capture-, ionization-, and radiative-decay processes, play an important role in the stopping process in plasma.

Low-velocity impacts into granular material: application to small-body landing

Abstract: With the flourishing number of small body missions that involve surface interactions, understanding the mechanics of spacecraft - surface interactions is crucial for improving our knowledge about the landing phases of space missions, for preparing spacecraft operations, and for interpreting the results of measurements made during the surface interactions. Given their regolith-covered surfaces, the process of landing on a small body can be considered as an impact at low-velocity onto a granular material in reduced-gravity. In order to study the influence of the surface material, projectile shape, and gravity on the collision dynamics we used two experimental configurations (one for terrestrial gravity experiments and one for reduced-gravity experiments) to perform low-velocity collisions into different types of granular materials: quartz sand, and two different sizes of glass beads (1.5 and 5 mm diameter). Both a spherical and a cubic projectile (with varying impact orientation) were used. The experimental data support a drag model for the impact dynamics composed of both a hydrodynamic drag force and quasi-static resistance force. The hydrodynamic and quasi-static contributions are related to the material frictional properties, the projectile geometry, and the gravity. The transition from a quasi-static to a hydrodynamical regime is shown to occur at lower impact velocities in reduced-gravity trials than in terrestrial gravity trials, indicating that regolith has a more fluid-like behaviour in low-gravity. The reduced quasi-static regime of a granular material under low-gravity conditions leads to a reduction in the strength, resulting in a decreased resistance to penetration and larger penetration depths.

High-velocity impact response of fiber metal laminates: Experimental investigation of projectile's deformability

Abstract: The aim of this research is to investigate the influence of projectile's deformability on ballistic impact response of fiber metal laminates. High-velocity impact experiments have been carried out via a light gas gun setup using rigid, semi-rigid and deformable projectiles with the same diameter, nose shape and mass. Fiber metal laminates have been made of two identical aluminum facing plates and different number of glass/epoxy composite plies in the middle. Several local and global mechanisms for kinetic energy absorption of projectiles have been detailed and ballistic limit velocity, as well as specific perforating energy for all cases have been determined. The results indicated that by increasing the deformability of the projectile, the amount of local and global wasting energy mechanisms for dissipating the velocity of projectiles have been increased. Furthermore, the interaction between non-rigid projectiles and fiber metal laminate targets as well as permanent deformation of non-rigid projectiles, had important effects on preventing the projectile penetration. By increasing the deformability of projectiles and/or increasing the number of composite plies, permanent deformation of facing plates, fiber breakage, crushing as well as delamination and debonding have been increased and local damage modes in facing plates changed from petalling to plugging. Besides, rigid projectiles possessed less specific perforating energy compared with deformable projectiles and required minimum initial velocity for full penetration.

Impact of Armor-Perforating Projectile on a Bullet-Resistant Silicon-Carbide-Graphene Composite Through Finite Element Method

Abstract: With the advancement in the defence technologies of the military sector of the world, the chances of encountering life threats have also increased. Police personnel and the armed forces deal with such situations regularly during their duty. The most common of such situations is injuries and life threats due to small arms and light weapons. Thus, there is an emerging need for advancement in the study and manufacturing of bullet-resistant or bullet-proof materials to avoid the harms created by ballistic impacts of a projectile. This paper studies the effect of Young’s modulus of the material and thickness of the target plate on residual velocity of the projectile through finite filament modeling. Simulations were carried out to study the effect of adding graphene to silicon carbide matrix to the penetration of the projectile and to find out the minimum thickness of the composite plate required to resist the complete perforation of the projectile.

Parametric analysis of energy absorption capacity of thin aluminum plates impacted by rigid spherical projectiles

Abstract: A finite element axisymmetric model has been developed to study the energy absorption capacity of thin Aluminum plates (0.2–20 mm thickness) in terms of the ballistic limit. The Johnson-Cook material model was used to describe the mechanical behavior of the 2024-T3 Aluminum. Numerical results were validated by comparison with experimental tests carried on similar plates using a gas gun with two high-speed cameras to measure impact velocities in the order of 100 m/s to 200 m/s. Plastic work (60%) and friction (10%) dissipate the impact energy, while the remaining energy is absorbed in the plate as elastic and kinetic energy. A parametric analysis was performed for projectile radius and plate thickness to study their influence on the perforation energy. Ballistic curves and energy balances were used to obtain the ballistic limit from numerical simulations. Ballistic limit shows a non-linear relation with plate thickness to projectile diameter ratio, while the mean perforation stress shows a linear relation with plate thickness to projectile diameter ratio. From numerical results, a semi-empirical relation is suggested to estimate mean perforation stress and consequently obtain the ballistic limit for a given plate-projectile configuration.

Multi-particle production in proton-nucleus collisions in the Color Glass Condensate

Abstract: We compute multi-gluon production in the Color Glass Condensate approach in dilute-dense collisions, pA, extending previous calculations up to four gluons. We include the contributions that are leading in the overlap area of the collision but keep all orders in the expansion in the number of colours. We develop a diagrammatic technique to write the numerous colour contractions and exploit the symmetries to group the diagrams and simplify the expressions. To proceed further, we use the McLerran-Venugopalan and Golec-Biernat-Wusthoff models for the projectile and target averages, respectively. We use a form of the Lipatov vertices that leads to the Wigner function approach for the projectile previously employed, that we generalise to take into account quantum correlations in the projectile wave function. We provide analytic expressions for integrated and differential two gluon cumulants and show a smooth dependence on the parameters defining the projectile and target Wigner function and dipole, respectively. For four gluon correlations we find that the second order four particle cumulant is negative, so a sensible second Fourier azimuthal coefficient can be defined. The effect of correlations in the projectile on this result results qualitatively and quantitatively large.

Ballistic Efficiency of Multilayered Armor System Reinforced with Jute-Kevlar Epoxy Composite against High-Energy Steel Core Projectile

Abstract: For protection against high velocity projectile such as 7.62 mm or 5.56 mm, multilayered armor system (MAS) is suitably the best option. In the present work, the experimental study on MAS with a front Al2O3 ceramic tile followed by a composite of jute and kevlar reinforced with epoxy matrix has been studied. The analytical result has found to meet the performance requirement as specified by NIJ0101.06 when tested against 7.62 mm hard steel core (HSC) and mild steel core (MSC) projectile. It was found that all MAS with double ceramic tile has successfully defeated HSC and MSC projectile with maximum observed back face signature (BFS) as 26.71 mm and 28.70 mm, respectively. In case of single monolithic ceramic, 25.80 mm and 35.12 mm were the maximum observed BFS against HSC and MSC projectile. The extent of projectile damage has been more in HSC when compared to the MSC. Blunt erosion and core breakage were peculiar observations in HSC core, whereas a mushrooming and bulging were observed in MSC core. Macro- and SEM analysis of MAS has been studied to understand the energy dissipation and failure mechanism.

FEM Simulation of High Speed Impact Behaviour of Additively Manufactured AlSi10Mg Alloy

Abstract: The present work investigates impact behaviour of additively manufactured AlSi10Mg alloy and ballistic limit of projectiles using FEM simulations. Tensile tests, dynamic tests and elevated temperature tensile tests simulations were performed on smooth and notched specimens to calculate Johnson–Cook material and damage model parameters, which are subsequenty given as inputs for impact simulation. The relationship between residual velocity versus initial projectile velocity is expressed using Jonas–Lambert’s model for calculating ballistic limit. The effects of projectile velocity, its shape, thickness and material property of AlSi10Mg on ballistic limit were thoroughly investigated. C3D8R elements are used to discretize the target plate and mesh transition zone was created in impact region. Johnson–Cook elasto-viscoplastic model was employed to study the ballistic resistance behaviour of AlSi10Mg alloy. Fracture energy value of 43.6 kN/m for AlSi10Mg alloy is used to initiate the damage in target plate. All FE simulations were performed by using ABAQUS/Explicit. It is observed that ballistic impact on 3D printed AlSi10Mg has shown plugging and petaling failure when hemispherical projectile was used while plugging failure in the case of blunt projectiles. The ballistic limit of hemispherical projectiles is found to be higher (311 m/s, 400 m/s) compared to the blunt projectiles (216.5 m/s, 245 m/s). The impact velocity to completely penerate 6 mm thick target plate is relatively higher as compared to 3 mm thick target plate for both projectiles.