Projectile Number Research Articles

On the penetration efficiency of ceramic fragments through steel targets

Abstract The penetration efficiency of novel ceramic fragments should be investigated, and their weapon damage effectiveness must be evaluated. In this study, the efficiency of ceramic fragments in penetrating steel targets were analyzed through ballistic impact tests and numerical simulations. The penetration patterns of these ceramic fragments through steel targets indicate significant perforation. It was deduced that the thicker the steel target, the greater the ability of ZrO2 ceramic fragments to penetrate. Results indicate that the thicker the steel target, the greater the ability of ZrO2 ceramic fragments to expand their perforation, while that of Al2O3 ceramic fragments is reduced as the thickness of the steel target is increased. In addition, the number of projectiles triggered by the perforation of the two ceramic fragments behind the targets decreases as the thickness of the steel target increases. Thus, the higher the impact velocity, the larger the perforation diameter of the ceramic fragments, and the larger the number of projectiles behind the target. Under the same impact velocity, the penetration ability of a ZrO2 ceramic fragment on steel targets was better than that of an Al2O3 ceramic fragment, and the number of projectiles behind the target was greater.

Penetration trajectory of rigid projectile in the heterogeneous meso-scale concrete target

For the normal penetration of a symmetrical rigid projectile into a concrete target with coarse aggregates, the lateral deflection may occur under certain conditions depending on geometrical parameters of the projectile, impact velocity and coarse aggregate distribution. In this work, four dimensionless numbers of projectile, that is, impact factor [Formula: see text], length-to-diameter ratio [Formula: see text], nose factor [Formula: see text] and the relative location of mass center [Formula: see text], are employed to study the effects of projectile parameters on the deflection of penetration trajectory. Numerical studies based on three-dimensional (3D) meso-scale concrete model are conducted and the projectile trajectories are obtained under different dimensionless numbers. According to the development of the deflection angle during the rigid projectile penetration into meso-scale concrete, the motion of the projectile can be divided into four stages, that is, initial deflection, rapid change, deflection rebound and final stage. The numerical results show that, for the same meso-scale concrete target, the deflection of the projectile trajectory becomes larger with the increases of [Formula: see text], [Formula: see text] and [Formula: see text], while the deflection angle of projectile decreases with the increase of [Formula: see text].

ERYA-Bulk and ERYA-Profiling: An application for quantitative PIGE analysis

The applications entitled ERYA-Bulk and ERYA-Profiling (ERYA stands for Emitted Radiation Yield Analysis) are two programs which implement PIGE (Particle Induction Gamma-Ray Emission) analysis of samples which can be either homogeneous (handled by ERYA-Bulk) or heterogeneous (with multiple layers, which are simulated by ERYA-Profiling).The homogeneous model uses an analytical method to evaluate the nuclear yield as function of the mass fraction of the element(s) of interest. A routine is available to fit the experimental yields in order to compute the correct sample atomic composition.Otherwise, the heterogeneous model takes consideration of the physics with greater detail, including straggling in the energy lost by the projectiles, making a more realistic yield simulation, whose level of accuracy the user can control in exchange of computational time.Here, we present the latest developments of these codes, which include new features, functionalities and direct handling of different source files. ERYA-Bulk and ERYA-Profiling are currently compiled and tested for Linux, Windows and Mac OS X operating systems. Program summaryProgram Title: ERYA-Bulk, ERYA-ProfilingCPC Library link to program files:https://doi.org/10.17632/gnrvm4jt5v.1Developer's repository link:https://github.com/Arucard1983/ERYA-Bulk (ERYA-Bulk), https://github.com/Arucard1983/ERYA-Profiling (ERYA-Profiling)Licensing provisions: LGPL-v3Programming language: C++External routines: wxWidgets [1], wxMathPlot [2]Nature of problem: Compute the gamma-ray yield coming from a sample bombarded by a energetic (few MeV) beam of charged particles (namely protons). The yield corresponding to a given element depends on the mass fraction of this element and on the major composition of the sample which determines the rate of energy loss by the beam. It also depends on the detector efficiency, the collected beam charge (i.e., number of projectiles) and the cross-sections of the relevant gamma-producing nuclear reaction.All data inputs can be loaded from a file or inserted by the user. The energy straggling along the beam interaction with the sample, irrelevant for bulk analysis, is determinant for depth profiling.Solution method: The yield calculation is made by numerical integration of an analytical formula that depends on several quantities which can be analytical in nature or approximated by interpolation (the cross-section data interpolation is one example).The straggling and energy dispersion also depends on energy distributions which have different numerical approximations. A modular approach using the object-oriented programming helps to implement different models to the main integration routine, and make the source code more readable and prone for future extensions.A fitting feature was implemented on ERYA-Bulk to adjust the sample composition to the experimental yield results.

Numerical simulation of 3D barrel system based on thermal-structural coupling under continuous firing

In order to study the laws of temperature field and deformation field of the 5.56mm rifle under continuous firing, the barrel system was taken as the research object, the transient temperature field and the deformation field of the 3-D barrel system under continuous firing of 150 rounds was calculated by using thermal-structural coupling method based on ANSYS. The temperature of multiple positions of the combat gun that partially removed the lower handguard was measured by the thermal imager. The difference between the test results and the simulation results was kept below 20%. The results of simulation and experiment showed: (1) The peripheral parts of the barrel have important influence on the temperature field and deformation field of the barrel system, and it is not negligible for the study of the thermal effects of combat gun under continuous firing. (2) The temperature of the inner wall increases with the number of projectiles under continuous firing, and the chromium layer has a significant effect of reducing thermal pulse. (3) Because the barrel is heated more unevenly, it will increase the inner diameter of the barrel and offset the axis. In a word, studying and analyzing the laws of temperature field and deformation field of the rifle can lay the foundation of the thermal management theory of firearms.

Comparison of the hydrodynamic ram caused by one and two projectiles impacting water-filled containers

High-velocity impact on fluid-filled containers is a concern associated with the vulnerability of aircraft fuel tanks due to hydrodynamic ram (HRAM). The present study compared the hydrodynamic ram caused by one and two spherical projectiles impacting water-filled containers using a previously developed and validated numerical model. Two types of comparisons were conducted to study the difference in pressure distribution inside the water and energy-time history of various parts, respectively. The propagation velocity of the superimposed shock wave in the two-projectile cases is higher than the shock wave in the one-projectile cases. The change in the energy of the entry plate is not affected by the number of projectiles, while more of the energy from water is transferred to the exit plate in the two-projectile cases compared to the one-projectile cases.

Multiparametric Investigation of Thermal Limitations in a Rapid-Fire Multirail Railgun Powered by a Pulsed MHD Generator

The operation of rapid burst firing multi-rail railguns was analyzed by numerical simulation using coupled 2-D and 3-D nonstationary formulations. In the calculations, a Sakhalin-type pulsed magnetohydrodynamic generator is assumed as a power source for the launcher. Launchers with three and five pairs of parallel rails connected into a series electrical circuit are considered. The simulation was performed for different numbers of projectiles in a burst and for different projectile masses. It is established that a major factor limiting the operation of launchers in such modes is the heating of the rails. It is shown that the rate of rail heating is determined by the inhomogeneity of the current density distribution along the rail section due to the nonstationary diffusion of the magnetic field into the rails and by the velocity skin effect. It has been shown previously that the maximum heating of the rails occurs in regions located outside the launcher channel provided that the width of the outer rail extends beyond the section of the launcher channel. We investigated the possibilities of reducing the heating of rails in these regions using rails of different widths in the rail launcher channel, using rails of different materials and rails with inhomogeneous electrophysical properties, and using armatures of different materials. The calculations show that with an optimal choice of the material and structure of the rails and the armature material corresponding to this structure, multirail launchers 5–6-m long can provide a projectile velocity of 2–2.5 km/s in a burst of 10–16 projectiles with masses of up to 800 g at a firing rate of 200–300 shots per second with no melting of the rails in the launcher channel.

Reaction Cross Section of Heavy Projectiles Using Coulomb Modified Glauber Model

We investigated reaction cross section and inelastic collisions of the wide number of projectile and target nuclei using the Coulomb Modified Glauber Model (CMGM). The total reaction cross sections were calculated with and without accounting for in-medium effect for various heavy projectiles such as 56Fe26, 84Kr36, 132Xe54, 197Au79 and 238U92 that interact with Nuclear Emulsion Detector’s (NED) nuclei at incident energies at around 1 GeV/n. The calculated average values of reaction cross section are compared with the corresponding experimental data.

Numerical study on the perforation of steel plates by multiple projectiles

PurposeMetal plates are usually used as protective shields of engineering structures, which probably undergo multiple projectile impacts resulting from gunshot and blast. Though a large number of studies have been conducted on the performance of metal plates under a single projectile impact, few studies have explored their performance under multiple projectile impacts. This paper aims to explore the performance of Weldox 460 E steel plates against multiple projectile impacts through numerical simulation.Design/methodology/approachA three-dimensional coupled finite element (FE) and smoothed particle hydrodynamics (SPH) model was developed to simulate the perforation of a 12-mm-thick Weldox 460 E steel plate by an ogival projectile. The model was verified by existing experimental data. Then, it was extended to investigate the same target plate subjected to impacts with multiple projectiles. Simultaneous impacts with different number of projectiles, as well as sequential impacts with two projectiles, were considered.FindingsEffects of spacing between projectiles on residual velocity of projectile, ballistic limit and failure mode of target were revealed for simultaneous impacts. Effects of spacing and axial distance between projectiles on residual velocity of projectile were explored for sequential impacts.Originality/valueThis work developed an advanced FE–SPH model to simulate perforation of steel plates by multiple projectiles, and revealed the effects of multiple impacts on ballistic performance of steel plates. It provides guidance for the design of protective structures/shields in various engineering applications.

Rail Heating in a Rapid-Fire Multirail Launcher Powered by a Pulsed MHD Generator

The operation of electromagnetic multirail launchers of solids in the mode of rapid-fire sequential launching of several projectiles has been studied by a combined 2-D and 3-D nonstationary numerical simulation. A Sakhalin type pulsed magnetohydrodynamic generator is used in the calculations as a power supply for the launchers. Launchers with three or five pairs of parallel rails connected into a series electrical circuit are considered. The acceleration of different numbers of projectiles in a burst and for different masses of projectiles is simulated. It has been found that the heating of the rails is a major factor that limits the operation of the launchers in these modes. An essential feature that determines the rate of rail heating is the nonuniform current density distribution over the rail cross section due to the nonstationary diffusion of the magnetic field into the rails. The calculations taking into account the nonstationary distribution of currents in the rails of a multirail launcher have shown that an appropriate choice of the mass of projectiles, their number in a bursts on the order of five projectiles with a firing frequency on the order of 200 Hz, it is possible to accelerate projectiles weighing up to 800 g to velocities 1.8–2.5 km/s without the rails melting.

Anomalous Positive Ion Formation in Negative Ion Collisions with HOPG

Charge transfer on graphite, a typical substrate and one of the fusion first wall materials, is of great importance in the plasma–wall interaction, thin-film growth, and surface catalysis. We present an experimental study of 8.5–22.5 keV energy carbon, oxygen, and fluorine negative ions scattering from a highly oriented pyrolytic graphite (HOPG) surface at a scattering angle of 8°. It is found that the positive ion fraction decreases monotonically with the increase of both incident velocity and angle. In particular, these dependences are very different from those presented in previous studies. A molecular dynamics simulation reveals that, around the critical condition for planar surface channeling, a number of projectiles may penetrate into the subsurface and become energetic atoms when they emerge from the surface. Hence, an exponential scaling related to the penetration probability has been proposed to well describe the velocity and angle dependences of positive ion fractions.

Geant4-DNA simulations using complex DNA geometries generated by the DnaFabric tool

Several DNA representations are used to study radio-induced complex DNA damages depending on the approach and the required level of granularity. Among all approaches, the mechanistic one requires the most resolved DNA models that can go down to atomistic DNA descriptions. The complexity of such DNA models make them hard to modify and adapt in order to take into account different biological conditions. The DnaFabric project was started to provide a tool to generate, visualise and modify such complex DNA models. In the current version of DnaFabric, the models can be exported to the Geant4 code to be used as targets in the Monte Carlo simulation. In this work, the project was used to generate two DNA fibre models corresponding to two DNA compaction levels representing the hetero and the euchromatin. The fibres were imported in a Geant4 application where computations were performed to estimate the influence of the DNA compaction on the amount of calculated DNA damage. The relative difference of the DNA damage computed in the two fibres for the same number of projectiles was found to be constant and equal to 1.3 for the considered primary particles (protons from 300 keV to 50 MeV). However, if only the tracks hitting the DNA target are taken into account, then the relative difference is more important for low energies and decreases to reach zero around 10 MeV. The computations were performed with models that contain up to 18,000 DNA nucleotide pairs. Nevertheless, DnaFabric will be extended to manipulate multi-scale models that go from the molecular to the cellular levels. Program summaryProgram title: DnaFabricCatalogue identifier: AEZV_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEZV_v1_0.htmlProgram obtainable from: CPC Program Library, Queen’s University, Belfast, N. IrelandLicensing provisions: Apache License, 2.0No. of lines in distributed program, including test data, etc.: 13514No. of bytes in distributed program, including test data, etc.: 186753Distribution format: tar.gzProgramming language: C++.Computer: Computer with a GPU and OpenGL3.3 compatible drivers.Operating system: Linux (Ubuntu).RAM: 4 gigabytesClassification: 3, 14, 20.External routines: Qt5 and OpenGL3.3Nature of problem:Simulations implying DNA geometrical models often show limitations to support the huge number of DNA constituents. In order to allow users to build, visualise and perform calculations on detailed DNA models including hundreds of thousands of DNA elements, a dedicated framework is needed.Solution method:The DnaFabric library is a framework that allows users to easily build their own DNA models, display them and perform calculations. The DnaFabric includes: hierarchically organised DNA models (binary-executable example named “Fibre”), a dedicated 3D render engine, an optimised OpenGL interface and some multi-threading facilities.Unusual features:The DnaFabric uses 3D technologies from the computer graphics world allowing the rendering of huge DNA models in real-time.Additional comments:Three examples are provided in the Examples folder. The “Basic” example describes how to set-up a simple DnaFabric user-application. The “Fibre” example shows the two DNA fibre models used for the calculations in this paper. The “MovingSpheres” example, demonstrates how to implement a simulation interacting with the DNA geometrical model.Running time:Once a user application is started, an auto-generated window will show the 3D model. The efficiency of the rendering depends highly on the user hardware. However, the user can customise each of the rendered elements contained in its application to adjust the required computer power.

Partial inelasticity coefficients of negative pions in p, d, α, 12C+12C and p, 12C+181Ta collisions at 4.2 GeV/c per nucleon

The partial inelasticity coefficients of the negative pions were determined in minimum bias p, d, α, 12 C +12 C and p, 12 C +18 Ta collisions at 4.2A GeV/c taking into account the average number of participant nucleons of a projectile nucleus. In nucleus–nucleus collisions, the average values of partial inelasticity coefficients (〈K(π-)〉) of the negative pions did not depend on the mass numbers of projectile and target nuclei. Increase of 〈K(π-)〉 in going from p+12 C to d, α, 12 C +12 C collisions was due to an additional source of production of fast negative pions in nucleus–nucleus collisions — a charge exchange conversion of one or more neutrons of a projectile nucleus into a proton and π-. Linking the experimental results of the present analysis at intermediate energy with those obtained at high and ultra-high energies, it was concluded that the average values of partial inelasticity coefficients of pions in nucleon–nucleus and nucleus–nucleus collisions manifest a transitive behavior. At intermediate energies, the values of 〈K(π-)〉 were smaller by a factor of two and more as compared to those at high energies, and they increased further with increasing incident energy, reaching a plateau at E0 > 100A GeV.

Metal projectile injuries in cats: review of 65 cases (2012-2014).

The objective of this study was to compare the prevalence of different types of injuries caused by various types of projectiles among urban, suburban and rural cats of different ages in order to predict the type of injury sustained. For the period 1 January 2012 to 30 April 2014, the medical records of cats with metal projectile injuries (PIs) were searched from the archive of the university's small animal diagnostic imaging centre. Age, sex, owner address, admission during a weekend or on a working day, month of admission, projectile position (head and neck; thoracic region; abdominal region, including lumbosacral spine; forelimbs; and hindlimbs, including tail), number of projectiles, presence of a wound and fracture related to the projectile, and the type of projectile were recorded for each cat. Sixty-five cats with PIs were admitted during the defined period. In 38.5% of cats the projectiles found upon radiography were incidental findings. The frequency of PIs peaked in March. Airgun projectiles were found in 80.0% of the cats. PIs in two or more body regions were found in 29.2% of the cats. Among the cats that had only been shot in one body region, the projectile was most frequently found in the abdominal region, including the lumbosacral spine (41.3%). These results might prompt clinicians to evaluate closely and screen for feline PIs in emergency situations.

Design Considerations for an Electromagnetic Railgun Firing Intelligent Bursts to Be Used Against Antiship Missiles

Railguns can reach higher muzzle velocities and fire rates than conventional guns. Muzzle velocities up to 2400 m/s and fire rates of more than 50 Hz have already been demonstrated with projectiles having a mass of 140 g and a square caliber of 25 mm. We investigated if a close-in weapon system (CIWS) based on a railgun performs better against incoming antiship missiles than a conventional CIWS such as the goalkeeper and propose solutions to optimize the performance of such a railgun. CIWSs are operational systems that defend a ship against incoming subsonic antiship missiles. However, the future antiship missiles will be supersonic and more difficult to defeat with conventional gun systems. Railguns are expected to perform better against these future threats thanks to their higher muzzle velocity and fire rate. Furthermore, the muzzle velocity within a single burst can be varied easily from shot to shot, generating a so-called intelligent burst. It allows varying the velocity of each projectile such that all projectiles arrive on the target at the same time. The number of projectiles, and thus the electrical energy required to achieve a target kill with an intelligent burst is expected to be lower than for railguns firing at constant muzzle velocity. In the first part, the performance of an electromagnetic CIWS is discussed using simulation models calculating the hit probability of a burst of projectiles fired with muzzle velocities ranging from 1200 to 2400 m/s and fire rates ranging from 75 to 300 rounds/s. The geometry of the target is that of a typical antiship missile, its velocity ranges from subsonic (300 m/s) to supersonic (600 m/s). The influence of the projectile mass on the performance of the system and the required electric energy was also investigated. We confirmed that the concept of intelligent burst reduces the required electric energy, especially against supersonic targets. The second part deals with some technical aspects of high fire rate railguns. We have shown experimentally that an automatic loading system allows increasing the fire rate of a medium caliber railgun from 50 to 75 Hz.

Multiparticle azimuthal correlations of negative pions in nucleus-nucleus collisions

Multiparticle azimuthal correlations of π − mesons have been studied in dC, HeC, CC, CNe, MgMg, (d, He)Ta, CCu, CTa, and OPb collisions at momentum of 4.2, 4.5 GeV/c per nucleon within the standard transverse momentum analysis method of P. Danielewicz and G. Odyniec. The data were obtained by SKM-200-GIBS and Propane Bubble Chamber Collaborations of JINR. The axis has been selected in the phase space and with respect to this axis π − meson correlations were observed. The values of the coefficient of the correlations linearly depend on the mass numbers of projectile (A P ) and target (A T ) nuclei. The Quark-Gluon String Model satisfactorily describes the experimental results.

Focus on ancient bombardment

The latest studies of asteroid impacts on Earth and the Moon beginning about 450 million years after the formation of the Solar System provide insight into the duration, number and size of these events. The Late Heavy Bombardment was a period of time, generally put at about 4.1 billion to 3.8 billion years ago, when the inner planets of the Solar System were subjected to a high-frequency barrage of asteroids. This left its mark on the Moon, but on Earth the craters quickly disappeared owing to tectonic processes and erosion. In the first of two papers on the bombardment, Brandon Johnson and Jay Melosh determine the properties of the asteroids by looking at spherule beds: layers of debris ejected during the impacts. The thickness of spherule layers is expected to vary according to the size of the impactor and the speed at which it hit Earth. This historical record of impacts indicates that the number of projectiles colliding with Earth was substantially higher 3.5 billion years ago than it is today, with a gradual decline in the number of strikes after the Late Heavy Bombardment. Bottke et al. modelled the evolution of an asteroid belt that extended farther towards Mars than the present one. They find that most of the impactors traced by the spherule beds probably originated in this 'E-belt', which was disrupted during migrations of some of the giant planets.

Multiple variations of firearm injuries - A case report

Variation from common findings in death due to firearm injury is not commonly encountered. When there is an atypical finding, the forensic pathologist may feel it difficult for differentiating firearm entry wound from firearm exit wound, tracing the wound track, estimating approximate range of firing and differentiating suicidal injury from homicidal injury. Failure to differentiate entry wound from exit wound can cause error in calculating number of projectiles entered into the body, lodged inside the body or exited through the body, besides posing problem in ascertaining direction of firing and direction of wound track etc. Failure to differentiate contact or close range firearm injury from distant range firearm injury can lead to wrong interpretation about the manner of death. The authors have reported a fatal case of rifled firearm injury showing multiple variations from common findings.

Slowing down of fast electrons as probe for charging and decharging dynamics of ion-irradiated insulators

The slowing down of fast electrons emitted from insulators [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Kr, Ag, Xe; 20--64 MeV/u) was measured by the time-of-flight method at LNS, Catania and GANIL, Caen. The charge buildup, deduced from both convoy- and binary-encounter electron peak shifts, leads to target material-dependent potentials (6.0 kV for Mylar, 2.8 kV for PP). The number of projectiles needed for charging up (charging-up time constant) is inversely proportional to the electronic energy loss. After a certain time, a sudden decharging occurs. For low beam currents, charging-up time, energy shift corresponding to maximum charge buildup, and time of decharging are regular. For high beam currents, the time intervals become irregular (chaotic).

Charging of insulators by multiply-charged-ion impact probed by slowing down of fast binary-encounter electrons

The interaction of ion beams with insulators leads to charging-up phenomena, which at present are under investigation in connection with guiding phenomena in nanocapillaries with possible application in nanofocused beams. We studied the charging dynamics of insulating foil targets [Mylar, polypropylene (PP)] irradiated with swift ion beams (C, O, Ag, and Xe at 40, 23, 40, and 30 MeV/u, respectively) via the measurement of the slowing down of fast binary-encounter electrons. Also, sandwich targets (Mylar covered with a thin Au layer on both surfaces) and Mylar with Au on only one surface were used. Fast-electron spectra were measured by the time-of-flight method at the superconducting cyclotron of Laboratori Nazionali del Sud (LNS) Catania. The charge buildup leads to target-material-dependent potentials of the order of 6.0 kV for Mylar and 2.8 kV for PP. The sandwich targets, surprisingly, show the same behavior as the insulating targets, whereas a single Au layer on the electron and ion exit side strongly suppresses the charging phenomenon. The accumulated number of projectiles needed for charging up is inversely proportional to electronic energy loss. Thus, the charging up is directly related to emission of secondary electrons.

Mechanism of Interior Ballistic Peak Phenomenon of Guns and Its Effects

The erosion and wear in the gun barrel will get worse with an increase in the number of projectiles fired. Generally speaking, the ballistic performance of the gun, measured through indicators such as the maximum pressure pm and the muzzle velocity v0, will decrease gradually due to gun barrel erosion. However, the above analysis does not agree with the firing test data of certain types of guns, especially of some small-caliber guns. The ballistic performance of such guns will exhibit an increase to their peak values followed by a gradual decrease with the number of rounds fired. This is the so-called interior ballistic peak phenomenon, also named as the hump effect. Taking several kinds of guns as examples, such as a 76 mm gun and a 100 mm gun, we calculated the engraving pressure p0 of the guns by an approximate method and built a lumped-parameter interior ballistic model of the guns that exhibits the effect, according to the interior ballistics theory of guns with erosion and wear. The results of the modeling of the guns under different wear conditions are close to the test data, showing the existence of the peak values of pm and v0. The simulation results of some of the other guns that exhibit this phenomenon also show good agreement. Furthermore, it can explain the double-peak phenomenon for some types of guns with double driving bands. It was proven that the mismatch of the structure and the dimensions of the gun bore with those of the projectile driving band is the fundamental cause of this effect. Due to the mismatch, the engraving pressure will first increase and then decrease with the enlargement of the bore dimensions caused by barrel erosion and wear. The variation in the engraving pressure p0 will inevitably lead to the variation in interior ballistic performance in the life cycle of the gun. This observed process appears to explain the interior ballistic peak phenomenon.