Showing papers on "Projectile published in 2018"
TL;DR: In this paper, the impact responses of UHPC targets with 3 volumetric% ultra-high molecular weight polyethylene (UHMWPE) fibres and UHMC targets with steel fibres are experimentally investigated subjected to high-velocity projectile penetration, and plain concrete targets under the same loading scenarios are also tested as control specimens for comparative purpose.
91 citations
TL;DR: Electronic stopping power in the keV/Å range is accurately calculated from first principles for high atomic-number projectiles and the effect of core states is carefully assessed.
Abstract: Electronic stopping power in the keV/A range is accurately calculated from first principles for high atomic-number projectiles and the effect of core states is carefully assessed The energy loss to electrons in self-irradiated nickel is studied using real-time time-dependent density functional theory Different core states are explicitly included in the simulations to understand their involvement in the dissipation mechanism The core electrons of the projectile are found to open additional dissipation channels as the projectile velocity increases Almost all of the energy loss is accounted for, even for high projectile velocities, when core electrons as deep as 2s^{2}2p^{6} are explicitly treated In addition to their expected excitation at high velocities, a flapping dynamical response of the projectile core electrons is observed at intermediate velocities The empirical reference data are well reproduced in the projectile velocity range of 10-120 au (15-210 MeV)
69 citations
TL;DR: In this article, a three-dimensional model was developed in the finite element solver ABAQUS/Explicit, which combines Lagrangian elements with Smoothed Particle Hydrodynamics elements.
Abstract: This paper focuses on the mechanical behaviour of aluminium alloy 2024-T351 under impact loading. This study has been carried out combining experimental and numerical techniques. Firstly, experimental impact tests were conducted on plates of 4 mm of thickness covering impact velocities from 50 m/s to 200 m/s and varying the stress state through the projectile nose shape: conical, hemispherical and blunt. The mechanisms behind the perforation process were studied depending on the projectile configuration used by analyzing the associated failure modes and post-mortem deflection. Secondly, a numerical study of the mechanical behaviour of aluminium alloy 2024-T351 under impact loading was conducted. To this end, a three-dimensional model was developed in the finite element solver ABAQUS/Explicit. This model combines Lagrangian elements with Smoothed Particle Hydrodynamics (SPH) elements. A good correlation was obtained between numerical and experimental results in terms of residual and ballistic limit velocities.
43 citations
TL;DR: In this article, the authors applied Visco-SCRAM and hot spot models to predict the ignition of HMX-based polymer bonded explosives (PBXs) under low velocity impact.
41 citations
TL;DR: In this paper, two sets of plain concrete target penetration tests are carried out with high strength steel alloy projectiles made of 30CrMnSiNi2A whereby the striking velocity ranges from 841 m/s to 1872 m /s.
41 citations
TL;DR: In this article, the damage and high-speed impact deformation mechanisms at elevated temperatures in honeycomb sandwich panels made from PM1000 and PM2000 alloys were investigated using a custom-made gas gun rig, and by using Finite Element and developing a phenomenological analytical model to predict the residual velocity and ballistic limit equations.
Abstract: This work presents an investigation on the damage and high-speed impact deformation mechanisms at elevated temperatures in honeycomb sandwich panels made from PM1000 and PM2000 alloys. The impact temperatures ranged from 22 °C to 866 °C. The investigation was performed experimentally using a custom-made gas gun rig, and by using Finite Element and developing a phenomenological analytical model to predict the residual velocity and ballistic limit equations for the case in which the diameter of the projectile is close or smaller to the honeycomb cell length. The sizes of the holes have been also evaluated by carrying out numerical thermal loading simulations on honeycomb sandwich specimen models impacted at high speed. The predictions provided by the Finite Elements and the analytical model give a good agreement with the results from the experimental tests. The hole diameters for the two idealized normal impact cases, in which the projectile hits the cell core and at the triple-wall intersection of the core, were also presented as a function of the projectile diameter and velocity in this paper.
32 citations
TL;DR: In this paper, a non-dimensional formulation of two analytical models has been developed (one for thin laminates and the other for thick ones) for the ballistic impact on E-glass woven fibres/polyester composite plates.
Abstract: This paper deals with the problem of high-velocity impact of a low-mass projectile on woven composite plates. A nondimensional formulation of two analytical models has been developed (one for thin laminates and the other for thick ones). Both analytical models are based on energy conservation and have been applied for the ballistic impact on E-glass woven fibres/polyester composite plates. The results of the models (mainly the ballistic limits) have been compared with experimental results. The value of the ratio target thickness/projectile diameter determining whether the laminate behaves as thick or thin has been established.
31 citations
TL;DR: In this paper, it was shown that a cylindrical projectile penetrates the plate at a lower velocity than a spherical one, which is explained by spalling-like failure for thicker graphitic membranes.
31 citations
TL;DR: In this paper, the results of controlled experiments that were designed to test projectile points made from stones with varying impact strength were presented, showing that highly homogenous fine-grained materials with low impact strength (e.g., obsidian) perform well when penetrating elastic materials such as skin and muscle.
29 citations
TL;DR: In this paper, a series of experiments were performed to study the deformation and failure of fluid-filled vessel subjected to high speed impact loading, and the results indicated that the hydrodynamic ram effect in the water-filled tank increased the damage of the target panels.
28 citations
TL;DR: In this article, a mathematical model of sea-sky infrared radiation is deduced in LW (long wave) infrared 8.5 µm band by calculating the sea surface and sky infrared radiation.
TL;DR: In this paper, the authors presented the first fully validated and predictive capability to model the V0-V100 probabilistic penetration response of a woven fabric using a yarn-level fabric finite element model.
TL;DR: In this article, stable supercavitating flow was observed in a launch experiment of axisymmetric projectile when the upper side of the projectile coincides with the free surface, and a numerical approach using large eddy-simulation and volume-of-fluid methods, and good agreements were achieved between numerical and experimental results.
Abstract: Cavitating flow near free surface is a complicated issue and may provide new inspiration on high-speed surface cruising. This study observes stable supercavitating flow as a new phenomenon in a launch experiment of axisymmetric projectile when the upper side of the projectile coincides with the free surface. A numerical approach is established using large eddy-simulation and volume-of-fluid methods, and good agreements are achieved between numerical and experimental results. Supercavity formation mechanism is revealed by analyzing the experiment photographs and the iso-surface of 90% water volume fraction in numerical results. The entrainment of a large amount of air into the cavity can cause the pressure inside the cavity to similarly increase with the pressure outside the cavity, which makes the actual cavitation number close to zero and is similar to supercavitation. Cases with various headforms of the projectile and cavitation numbers on the cavitating flow, as well as the drag reduction effects are further examined. Results indicate that the present strategy near the free surface could possibly be a new effective approach for high-speed cruising after vigorous design optimization in the future.
TL;DR: In this article, the authors investigated the relationship between measurements of the splash-up flow on the structure wall and the force measurements using the Euler model and found that the uniform vertical velocity profile assumption used in the euler model yields a better estimate for the impact force than the linear and hydrostatic assumptions.
TL;DR: In this article, a series of scaled penetration experiments with ogive-nosed, steel projectiles penetrating into medium strength concrete cylindrical targets were conducted, where the trajectories of the projectiles were recorded with a high-speed camera system.
TL;DR: A simple energy scaling can explain the energy transfer in both soft-particles and hard-particle granular targets, and the dissipative-diffusion model of energy transfer can quantitatively explain these behaviors.
Abstract: The impact-induced energy transfer and dissipation in granular targets without any confining walls are studied by microgravity experiments. A solid projectile impacts into a granular target at low impact speed (0.045≤v_{p}≤1.6 m s^{-1}) in a laboratory drop tower. Granular clusters consisting of soft or hard particles are used as targets. Porous dust agglomerates and glass beads are used for soft and hard particles, respectively. The expansion of the granular target cluster is recorded by a high-speed camera. Using the experimental data, we find that (i) a simple energy scaling can explain the energy transfer in both soft-particle and hard-particle granular targets, (ii) the kinetic impact energy is isotropically transferred to the target from the impact point, and (iii) the transferred kinetic energy is 2%-7% of the projectile's initial kinetic energy. The dissipative-diffusion model of energy transfer can quantitatively explain these behaviors.
TL;DR: In this paper, a scaling law was used to predict the performance of targets perforated in ductile hole formation with a high level of confidence, an example of which is provided for the 12.7 mm APM2 projectile against a range of aluminium alloys.
TL;DR: In this article, a light gas gun is used to accelerate different projectiles into water at different entry velocities and entry angles, and the results indicate that the drag coefficient is primarily controlled by the nose shape but is independent of the length to diameter ratio of the projectile.
TL;DR: In this paper, the effect of lateral displacement was examined for cross-ply laminates and the number of failed fibers was quantitatively determined and found to generally decrease from the impact surface to the rear surface.
TL;DR: In this paper, the excitation functions for the evaporation residues populated in the interaction of C 13 + 165 Ho system have been measured at projectile energies ≈ 4-7 MeV/nucleon.
TL;DR: In this paper, the impact performance of two-stage EFP and rigid-force EFP was evaluated on concrete targets, which consists of a precursor and a rigid EFP.
30 Aug 2018
TL;DR: A series of cratering experiments were performed where the response of the Ultra-High-Performance Fibre-Reinforced Concretes with various fibre volume fractions to the high velocity projectile impact loading was investigated as discussed by the authors.
Abstract: A series of cratering experiments were performed where the response of the Ultra-High-Performance Fibre-Reinforced Concretes with various fibre volume fractions to the high- velocity projectile impact loading was investigated. It was found that the increment of the fibre volumetric fraction did not have a significant influence on the depth of the penetration, but it was very effective in reducing the crater area and volume.
TL;DR: In this article, a single-stage gas gun testing methodology was used to estimate the required pressures for a targeted velocity, and the transmitted impact force was measured with four load cells installed behind the testing frame.
TL;DR: In this article, an improved analytical model able to simulate normal ballistic impacts of blunt shaped equivalent projectiles against ceramic tiles, without any backing plate, is described, and the model is compared with experimental data both from the literature and from ballistic tests, with actual bullets, performed by authors, predicting the residual velocity and the residual mass of the projectile.
TL;DR: In this article, a numerical model based on a computer program called LS-DYNA was validated with experimental data concerning the depth of penetration (DOP) and crater diameter of reinforced RPC targets.
TL;DR: In this paper, the Lattice Discrete Particles Model (LDPM) was used to simulate the medium-caliber hard projectile perforation of steel rebar reinforced concrete panels by using a constant area and shape partition method to determine the Gauss integration points distribution for beam elements.
TL;DR: In this article, the Lattice Discrete Particles Model (LDPM) is used to deal with the projectile size effect on penetration resistance via mesoscale constitutive laws governing the interaction between adjacent particles.
TL;DR: In this paper, a set of simulations has been carried out using smoothed particle hydrodynamics (SPH) technique of Autodyn for estimation of primary fragment characteristics (mass, velocity and exit angle) for assessing subsequent structure damage potential.
TL;DR: In this paper, a general quantum-kinetic approach for calculating ion-induced secondary electron emission spectra at impact energies where the emission is driven by the internal potential energy of the ion is presented.
Abstract: Using a helium ion hitting various metal surfaces as a model system, we describe a general quantum-kinetic approach for calculating ion-induced secondary electron emission spectra at impact energies where the emission is driven by the internal potential energy of the ion. It is based on an effective model of the Anderson-Newns-type for the subset of electronic states of the ion-surface system most strongly affected by the collision. Central to our approach is a pseudo-particle representation for the electronic configurations of the projectile which enables us, by combining it with two additional auxiliary bosons, to describe in a single Hamiltonian emission channels involving electronic configurations with different internal potential energies. It is thus possible to treat Auger neutralization of the ion on an equal footing with Auger de-excitation of temporarily formed radicals and/or negative ions. From the Dyson equations for the projectile propagators and an approximate evaluation of the self-energies, rate equations are obtained for the probabilities with which the projectile configurations occur and an electron is emitted in the course of the collision. Encouraging numerical results, especially for the helium-tungsten system, indicate the potential of the approach.
TL;DR: In this article, a numerical study on the effect of free water content on the penetration of concrete targets subjected to ogival-nosed projectile impact is presented, which is based on a recently developed computational constitutive model for concrete.