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A detailed mapping of volcanic ballistic projectiles emplaced in a defined area, represents the starting point to derive preparatory data in hazard and risk studies of ballistics phenomena. Considering as case study the 3rd July 2019 paroxysmal eruption occurred at Stromboli volcano, we map and analyse at very high spatial resolution (8 cm) the distribution of the ballistic spatter clasts emplaced on the E flank of the volcano. The resulting map identifies and reproduces as geospatial polygon elements 152,228 spatter clasts with areal dimensions from 0.03 to 4.23 m2. Dispersed on 0.407 km2, the spatters cover an area of 29,000 m2 corresponding to an erupted products volume from 2.3 to 7.0 × 103 m3, calculated here for the first time. Spatial analyses indicate that the area mostly affected by the clasts emplacement is between N67.5 and N135 directions, identifying a preferential deposition between N112.50 and N123.75 directions. The clasts size distribution rapidly decreases with the size increase, highlighting a nearly constant ratio small/large clasts regardless the distance from the vent. Finally, additional investigations reveal that clasts dispersion parameters decrease progressively with the distance from the vent only along one direction (N67.5), highlighting how the morphology influences the deposition and remobilisation of mapped ballistics. [ABSTRACT FROM AUTHOR]

A mathematical simulation of the internal ballistics of a shot from a gun, depending on the design of the charge of the gun, has been performed. A general system of equations defining the unsteady movement of a two-phase gas–powder mixture in the channel of the barrel of a gun in the one-dimensional approximation is presented. Results of simulation of a shot from a gun charged with tubular powder or chopped powder are presented. The influence of the gradual ignition of a powder in a gun and of its nonstationary and erosion burning in it on the parameters of the ballistic process in the gun and the influence of the mass and disposition of an igniter in the gun on the dynamics of a shot from it were investigated. [ABSTRACT FROM AUTHOR]

A detailed mapping of volcanic ballistic projectiles emplaced in a defined area, represents the starting point to derive preparatory data in hazard and risk studies of ballistics phenomena. Considering as case study the 3rd July 2019 paroxysmal eruption occurred at Stromboli volcano, we map and analyse at very high spatial resolution (8 cm) the distribution of the ballistic spatter clasts emplaced on the E flank of the volcano. The resulting map identifies and reproduces as geospatial polygon elements 152,228 spatter clasts with areal dimensions from 0.03 to 4.23 m2. Dispersed on 0.407 km2, the spatters cover an area of 29,000 m2 corresponding to an erupted products volume from 2.3 to 7.0 × 103 m3, calculated here for the first time. Spatial analyses indicate that the area mostly affected by the clasts emplacement is between N67.5 and N135 directions, identifying a preferential deposition between N112.50 and N123.75 directions. The clasts size distribution rapidly decreases with the size increase, highlighting a nearly constant ratio small/large clasts regardless the distance from the vent. Finally, additional investigations reveal that clasts dispersion parameters decrease progressively with the distance from the vent only along one direction (N67.5), highlighting how the morphology influences the deposition and remobilisation of mapped ballistics. [ABSTRACT FROM AUTHOR]

A promising direction in barrel ballistics aimed at increasing the muzzle velocity of a projectile is the use of new propellants as an attached charge. This paper presents an experimental and theoretical method for determining the law of propellant combustion in a manometric experiment (in a closed volume). Within the framework of this method, a small number of experiments could be sufficient to determine a change in the law of combustion during the propellant burnout and depending on pressure. This method is demonstrated on the example of processing three experiments with model high-density propellant. The laws of combustion of high-density propellants, obtained in this study, can later be used to calculate the gas-dynamic parameters of a shot from a barrel system or a nozzle bomb (in a semi-closed volume) using these propellants. [ABSTRACT FROM AUTHOR]

This paper describes the method and results of an experimental study of unsteady burning rate of high-energy materials containing metal powder additives under depressurization at a rate of 140–160 MPa/s. The method based on stating and solving the inverse problem of internal ballistics is used to determine the unsteady burning rate. The studies are carried out for high-energy materials, including energy additives in the form of metal powders (ASD-4, ASD-6, and Alex aluminum powders), aluminum diboride, and dodecaboride. It is shown by analyzing the this study that the unsteady burning rate of high-energy materials under sharp depressurization is oscillatory and depends on the energy additive type. [ABSTRACT FROM AUTHOR]

Ballistic devices that generate radial pressure waves are used for the treatment of different therapeutic indications. In order to assess the effectiveness of these devices and to interpret and transfer the results of clinical trials, it is important to know their acoustic output. In this paper, two ballistic devices and their reproducibility at different clinically relevant settings were investigated in the same in-vitro test setup. Pressure curves were measured in water at different intensity levels and pulse repetition rates. The sound field parameters (peak pressures, positive pulse intensity integral) were calculated from the pressure curves. Additionally, the surface velocity of the applicator was determined in air using a vibrometer. Both devices show a good pulse-to-pulse reproducibility. While the peak maximum pressure and the positive pulse intensity integral decrease only slightly (pmax up to 12%, PII+ up to 18.8%) comparing 1 Hz and 25 Hz for one device, they drop sharply (pmax up to 68.4%, PII+ up to 90.2%) for the other device comparing 1 Hz to 21 Hz. The same effect was observed in the vibrometer measurements. The results show that with increasing pulse repetition rate the stability of the parameters varies between different devices. Hence, all sound field parameters should be compared before transferring settings from one device to another. [ABSTRACT FROM AUTHOR]

Knowledge of material behaviour under impact is of key importance to understand ballistic impact events on tissue. Bone—with its complex underlying microstructure—is no exception; the microstructural network in bone is not only crucial to its integrity, but also provides a pathway for energy dispersion upon impact (Piekarski in J Appl Phys 41:215–225, 1970). Synbone®, a Swiss-made polyurethane bone simulant, has been considered as a potential bone analogue, particularly for cranial structures (Smith et al. in Leg Med 17(5):427–435, 2015; Riva et al. in Forensic Sci Int 294: 150–159, 2019). This study focused on long bone models and cylinders available from Synbone®, with the aim of determining their efficacy for use in ballistic testing and recreation. Comparisons were made between porcine bone and multiple Synbone® models regarding projectile energy loss and damaged surface area using high-speed video and high-resolution photography. CT and reverse ballistics techniques were also used as diagnostic tools. A significant correlation was made between real bone and Synbone®'s ballistic cylinders in all aspects of this study; however, it was observed that osteoporotic cylinders and anatomical models differ significantly in their reaction to impact. Consequently, the use of Synbone® as a ballistic target simulant—particularly when legal or practical accuracy is essential—will need to be treated carefully, giving due attention to these limitations. [ABSTRACT FROM AUTHOR]

A mathematical model is developed to characterize the progressive time-evolution of a fragmenting incandescent object. The objective of these models is to provide a spatio-thermal footprint of the fragmentation field, which can be useful to guide fire safety rules in manufacturing workplaces, as well as to estimate fire hazards. Ascertaining the time-evolution of the temperature of the fragments is quite difficult to measure experimentally, which motivates the model development. Initially, analytical models based solely on ballistics, which provide qualitative trends, are developed to provide insight into the fundamental ratios that govern safe operating conditions. Thereafter, rapid numerical spatio-thermal models, which provide quantitative information, are then developed, based on particle methods. The model uses the released energy from the initial blast pulse to provide the starting kinetic energy of the system of particles and then numerically computes the trajectory and thermal state of the fragments under the influence ofdrag from the surrounding air,gravitational settling andconvective and radiative cooling. Numerical examples and provided and extensions to high-fidelity are discussed. [ABSTRACT FROM AUTHOR]

This paper presents a numerical study of perforation of the aluminiummulti-layered targets impacted by steel projectiles in the shape of a ball, nut and nail. For the construction of the protective panels arc-, rectangular-, V- and U-shaped sheets of metal were considered. During the tests the panel thickness was constant at 160 mm. The panels were composed of 1.5-mm-thick aluminium sheets, and the initial speed of debris was 500 m/s. A comprehensive numerical study indicated the shape of the layer that had superior ballistic resistance and the best strength-to-weight ratio. Computational analyses were also used to investigate the influence of thermal softening and strain rate hardening in the Johnson–Cook constitutive model on the ballistic performance of layered targets. The number of layers required to stop the penetrating objects was compared for the rigid and deformable projectiles. Based on the comparative studies, some guidelines for engineering tasks involving exploration of number of possible technical solutions were proposed. [ABSTRACT FROM AUTHOR]

Analytical formulas for calculating the maximum velocity of penetration of doublelayer cermet and ceramic/organic-plastic targets are obtained taking into account the structural characteristics of the target and the physical and mechanical properties of the projectile and target materials. Using these formulas, the ballistic resistance of targets was studied and the possibility of optimizing their structure was shown. The results agree qualitatively with available experimental data. The optimal relative thickness of the ceramic layer which provides maximum penetration velocity was determined at areal densities of the target of 30-50 kg/m for different substrate materials. It is found that these velocity values depend weakly on the areal density of the target and are mainly determined by the properties of the substrate material. [ABSTRACT FROM AUTHOR]

The purpose of the study is to accelerate the development of ceramic materials for armour applications by substantially increasing the information obtained from a high-energy projectile impact event. This has been achieved by modifying an existing test configuration to incorporate a block of ballistic gel, attached to the strike face of a ceramic armour system, to capture fragments generated during the ballistic event such that their final positions are maintained. Three different materials, representative of the major classes of ceramics for armour applications, alumina, silicon carbide, and boron carbide, have been tested using this system. Ring-on-ring biaxial disc testing has also been carried out on the same materials. Qualitative analysis of the fracture surfaces using scanning electron microscopy and surface roughness quantification, via stereo imaging, has shown that the fracture surfaces of biaxial fragments and ballistic fragments recovered from the edges of the tile are indistinguishable. Although the alumina and boron carbide fragments generated from areas closer to the point of impact were also similar, the silicon carbide fragments showed an increase in porosity with respect to the fragments from further away and from biaxial testing. This porosity was found to result from the loss of a boron-rich second phase, which was widespread elsewhere in the material, although the relevance of this to ballistic performance needs further investigation. The technique developed in this work will help facilitate such studies. [ABSTRACT FROM AUTHOR]

Reverse ballistic impact tests are widely used for studying dynamic responses because they provide more comprehensive and quantitative projectile/rod response results than forward impact tests. To examine equivalent forward and reverse conditions, a series of 8-cm length oxygen-free copper rods with varying length-diameter ratios was used in forward and reverse ballistic Taylor impact experiments with velocities and strain ratios of 104-215 m/s and 1.25 × 10-2.5 × 10 s, respectively. Digital image correlation (DIC) and traditional optical measurements were used to determine instantaneous responses at the μs level. Based on DIC, transient structural deformation, and plastic wave propagation, the forward and reverse length difference at similar velocities ranges from 2 to 6.95 %. Rules governing deformation from the perspective of energy, along with rules for changes in energy and plastic wave propagation were determined. The relative deformation energy error was below 5 % for target projectile mass ratios above 20. [ABSTRACT FROM AUTHOR]

Calculation-experimental studies of a high-velocity collision between VT1-0 titanium plates and ultrafine- and coarse-grained structures with a steel spherical impactor are illustrated. Fine-grained VT1-0 titanium plate samples have been obtained using the abc pressing method. Ballistic measurements have been performed using a 30-mm smooth-bore ballistic installation at velocities of about 2500 m/s. A high-velocity collision has been calculated in the scope of an elastoplastic model of interacting materials with regard to destruction and a different phase state at velocities reaching 15 km/s. It has been indicated that the mechanical properties of the VT1-0 alloy are improved when proceeding from a coarse-grained structure to an ultrafine- grained structure; however, in this case, the result of shock loading is hardly affected in the considered velocity range. Titanium plates can be used as screens to protect the main structure of the aircraft from a high-velocity collision. [ABSTRACT FROM AUTHOR]

The laws of combustion of powders under conditions close to those of firing an artillery shot have been investigated. A solid-state local heat ignition model was used, and the process of powder combustion was simulated on the basis of the notions of the Belyaev-Zel′dovich thermal combustion theory. The complete formulation of the combustion problem includes the nonstationary processes of heat propagation and chemical transformation in the k-phase, as well as the quasi-stationary processes in the chemically reacting two-stage turbulent boundary layer near the combustion surface related to the characteristics of the averaged nonstationary flow by the boundary conditions at the outer boundary of the boundary layer. The features of the joint solution of the equations of the thermal combustion theory and the equations of internal ballistics have been analyzed. The questions on the convergence of the conjugate problem have been considered. The influence of various factors on the rate of combustion of powder has been investigated. The investigations conducted enabled us to formulate an approximate method for calculating the nonstationary and erosion rates of combustion of artillery powders at a shot on the basis of the Lenouard-Robillard-Karakozov approach. [ABSTRACT FROM AUTHOR]

The objective of this paper is to study the effects of personal protective equipment (PPE) and specific PPE layers, defined as thermal/evaporative resistances and the mass, on heat strain during physical activity. A stepwise thermal manikin testing and modeling approach was used to analyze a PPE ensemble with four layers: uniform, ballistic protection, chemical protective clothing, and mask and gloves. The PPE was tested on a thermal manikin, starting with the uniform, then adding an additional layer in each step. Wearing PPE increases the metabolic rates $$ \left(\dot{\mathrm{M}}\right) $$, thus $$ \dot{\mathrm{M}} $$ were adjusted according to the mass of each of four configurations. A human thermoregulatory model was used to predict endurance time for each configuration at fixed $$ \dot{\mathrm{M}} $$ and at its mass adjusted $$ \dot{\mathrm{M}} $$. Reductions in endurance time due to resistances, and due to mass, were separately determined using predicted results. Fractional contributions of PPE's thermal/evaporative resistances by layer show that the ballistic protection and the chemical protective clothing layers contribute about 20 %, respectively. Wearing the ballistic protection over the uniform reduced endurance time from 146 to 75 min, with 31 min of the decrement due to the additional resistances of the ballistic protection, and 40 min due to increased $$ \dot{\mathrm{M}} $$ associated with the additional mass. Effects of mass on heat strain are of a similar magnitude relative to effects of increased resistances. Reducing resistances and mass can both significantly alleviate heat strain. [ABSTRACT FROM AUTHOR]

In a previous paper, we presented a scaling law for the ballistic-limit velocity for the 7.62 mm APM2 bullet and five aluminum alloy plates. This scaling law predicts that the ballistic-limit velocity is proportional to the square root of the product of the plate thickness and a material strength term. In this note, we show that this same scaling law can be used to accurately predict ballistic-limit velocity for the larger 12.7 mm APM2 bullet. [ABSTRACT FROM AUTHOR]

The 2014 Mount Ontake eruption started just before noon on September 27, 2014. It killed 58 people, and five are still missing (as of January 1, 2016). The casualties were mainly caused by the impact of ballistic blocks around the summit area. It is necessary to know the magnitude of the block velocity and energy to construct a hazard map of ballistic projectiles and design effective shelters and mountain huts. The ejection velocities of the ballistic projectiles were estimated by comparing the observed distribution of the ballistic impact craters on the ground with simulated distributions of landing positions under various sets of conditions. A three-dimensional numerical multiparticle ballistic model adapted to account for topographic effect was used to estimate the ejection angles. From these simulations, we have obtained an ejection angle of γ = 20° from vertical to horizontal and α = 20° from north to east. With these ejection angle conditions, the ejection speed was estimated to be between 145 and 185 m/s for a previously obtained range of drag coefficients of 0.62-1.01. The order of magnitude of the mean landing energy obtained using our numerical simulation was 10 J. [ABSTRACT FROM AUTHOR]

The sudden eruption of Mount Ontake on September 27, 2014, led to a tragedy that caused more than 60 fatalities including missing persons. In order to mitigate the potential risks posed by similar volcano-related disasters, it is vital to have a clear understanding of the activity status and progression of eruptions. Because the erupted material was largely disturbed while access was strictly prohibited for a month, we analyzed the aerial photographs taken on September 28. The results showed that there were three large vents in the bottom of the Jigokudani valley on September 28. The vent in the center was considered to have been the main vent involved in the eruption, and the vents on either side were considered to have been formed by non-explosive processes. The pyroclastic flows extended approximately 2.5 km along the valley at an average speed of 32 km/h. The absence of burned or fallen trees in this area indicated that the temperatures and destructive forces associated with the pyroclastic flow were both low. The distribution of ballistics was categorized into four zones based on the number of impact craters per unit area, and the furthest impact crater was located 950 m from the vents. Based on ballistic models, the maximum initial velocity of the ejecta was estimated to be 111 m/s. Just after the beginning of the eruption, very few ballistic ejecta had arrived at the summit, even though the eruption plume had risen above the summit, which suggested that a large amount of ballistic ejecta was expelled from the volcano several tens-of-seconds after the beginning of the eruption. This initial period was characterized by the escape of a vapor phase from the vents, which then caused the explosive eruption phase that generated large amounts of ballistic ejecta via sudden decompression of a hydrothermal reservoir. [ABSTRACT FROM AUTHOR]

A laboratory gun that uses compressed gas as its propellant was designed and tested for the study of small projectiles traveling in soils with initial velocities ranging from 50 to 200 m/s. The gun employed the use of air or helium with an electrically triggered, pneumatically piloted, solenoid valve. The triggering system was designed to provide remote activation. A photo gate speedometer was utilized to measure the exit velocity of each projectile. Details of the electro-pneumatic control system are presented in this paper along with the design of the gun assembly and its subsystems. The effects of different design parameters, including muzzle length, projectile mass, propellant type, and volume of compressed gas utilized, on projectile velocity were investigated. Statistical analysis of the gun performance is presented. The gun is currently being used to visualize the fundamental physics of rapid earth penetration in soils, using transparent soils. [ABSTRACT FROM AUTHOR]

The results of experimental and theoretical investigations of the operation and a two-stage light gas magnetoplasma launcher are presented. An optical method for measuring the velocity of small bodies (2-10 mm) has been developed and used in testing a combined gas discharger for micro- and macroparticle acceleration. The experimental results are in good agreement with the mathematical model of the two-stage light gas gun in the approximation of constancy of the accelerating pressure behind the striker. [ABSTRACT FROM AUTHOR]

The shape of spirals formed by the interaction of a circumstellar disk with the magnetosphere in the magnetic propeller regime is examined in the ballistic approximation. The problem is solved analytically. The spirals and their cross sections are illustrated graphically. The possible effect of the magnetic propeller effect on the observed spectra of stars is discussed. [ABSTRACT FROM AUTHOR]

The efficacy of a new blast-/ballistic-impact-mitigation concept is analyzed using advanced computational methods and tools. In this concept, the target structure is covered by a zeolite protective layer (with a layer of air between the two), which in turn is in contact with a water layer (treated as a nano-fluidic material) in front. The water molecules are forced to infiltrate zeolite nanopores under high-rate loading, following which the hydrogen bonds of the water molecules interact with the hydrophobic walls of the nanopores, causing the water to undergo an ordering-type phase transition and acquire high density. At the same time, a significant portion of the kinetic energy of the water molecules is converted to potential energy or dissipated as heat. All-atom molecular-level equilibrium and non-equilibrium molecular dynamics simulations were employed to properly capture the attendant nano-fluidics phenomena. As a result, the structure sustains a substantially lower peak load, and the (conserved) linear momentum is transferred to the structure over a longer duration. [ABSTRACT FROM AUTHOR]

The paper considers the ballistic design of spacecraft (SC) transfer to the neighborhood of the L point and subsequent entry of the SC into the halo orbit. Trajectory calculations of one-impulse Earth-halo orbit transfers with and without using a lunar gravitational maneuver are presented. For the calculation of one-impulse trajectories of Earth-halo-orbit transfers, an algorithm for constructing initial approximations is applied. These approximations are constructed by calculating and analyzing the isolines as a function of two variables. This function is represented by the pericenter height of the outgoing orbit over the Earth's surface. The arguments of the function are special parameters that characterize the halo orbit. The mentioned algorithm allows one to obtain halo orbits with specified geometrical characteristics both in the ecliptic plane, and in the plane orthogonal to it. The estimates of the characteristic velocity expenses for maintaining SC in the selected halo orbit are obtained. The described technique was used to search for working orbits of the Spectr-RG and Millimetron spacecraft. Examples of orbits obtained are presented. [ABSTRACT FROM AUTHOR]

This paper presents a physicomathematical model and a method for calculating the parameters of the transition of a SRM to steady-state operation based on the design features of the propellant charge, the initial conditions in the motor, and the interrelated processes such as the formation and motion of compression waves and shock waves in the channel of the charge; the motion and mixing of the igniter combustion products containing a condensed phase with the initial gas and the combustion products of the charge; gradual heating and ignition of the surface of the charge. The developed programis used to explain the difference between the experimental pressure-time curves in the region of the transition of a large-size motor model to steady-state operation, obtained in bench tests under atmospheric conditions and on a high-altitude test facility at an initial motor pressure of 0.25 · 10 Pa. It is shown that ignition of the charge in vacuum produces more favorable conditions for heat transfer than ignition at atmospheric pressure. In the channel, this is due to an increase in the velocity of the igniter combustion products behind the transmitted shock wave, and in the submerged region and the charge slots, due to the minimum absorption of the radiation from the combustion products by the rarefied initial gas (air) present there. [ABSTRACT FROM AUTHOR]

In this study, an algebraic current-voltage (I-V ) equation suitable for the hand-calculation of ballistic nano conductors is derived from Landauer's formulation. A voltage and temperature dependent resistance expression is also obtained. It is shown that the presented algebraic I-V expression and the original Landauer's formula give the same characteristics as expected. Moreover, the I-V characteristics of ballistic nano conductors are investigated and it is concluded that there is an inescapable nonlinearity originating from the curvature of Fermi-Dirac distribution function in low voltage range. Finally, the total harmonic distortion (THD) of a sample ballistic nano conductor caused from its low voltage nonlinearity is computed via HSPICE simulations [ABSTRACT FROM AUTHOR]

One-dimensional discrete element model for the ballistic impact is used to determine the depth of penetration of a bullet on a thick target. Discrete Element Method (DEM) is a numerical tool where a continuum is modelled as a network of masses connected by normal springs. A one-dimensional discrete element model is developed to obtain the displacements and forces associated with the ballistic impact on a thick target. The depth of penetration of the penetrator into the target is calculated from these DEM results. The simulated results of depth of penetration are found to be in reasonable agreement with the simulation results of other numerical approaches that are available in the literature. [ABSTRACT FROM AUTHOR]

n analysis for liner collapsing and jet/slug formation of a double-layer shaped charge (DLSC) is presented. Variations of the collapse angle, collapse velocity, and jet velocity of the DLSC are discussed. Numerical simulations based on the Lee-Tarver model are performed to have an insight into the jet formation. Ballistic tests are conducted using a conical (60°) metal liner 56 mm in diameter to have a contrast with an ordinary shaped charge jet. It is shown that the collapse angle and velocity are both increased by the convergent detonation wave in the DLSC. The jet velocity, kinetic energy, and ballistic capability are significantly increased by using the DLSC, and the DLSC is an efficient way to improve shaped charge performance. [ABSTRACT FROM AUTHOR]

comparative analysis of ballistic efficiency of various propellants containing Al, or Zr, or ZrH is performed. The analysis is carried out for compositions including various oxidizers and binders and, when applied to missiles, for different volume and mass characteristics. Replacement of aluminum with zirconium or its hydride is demonstrated to increase the missile velocity (or payload mass) almost for all compositions of composite solid propellants if the ratio of the propellant volume to the mass of the empty structure is smaller than approximately 1.0-1.4 liters/kg. [ABSTRACT FROM AUTHOR]

We conducted an experimental and analytical study to better understand the mechanisms and dominant parameters for 7.62 mm APM2 bullets that perforate 7075-T651 aluminum armor plates. The 7.62-mm-diameter, 10.7 g, APM2 bullet consists of a brass jacket, lead filler, and a 5.25 g, ogive-nose, hard steel core. The brass and lead were stripped from the APM2 bullets by the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel cores. These projectiles were fired from a rifle to striking velocities between 600 and 1,100 m/s. Targets were 20 and 40-mm-thick, where the 40-mm-thick targets were made up of layered 20-mm-thick plates in contact with each other. The measured ballistic-limit velocities for the APM2 bullets were 1% and 8% smaller than that for the hard steel cores for the 20 and 40-mm-thick targets, respectively. Thus, the brass jacket and lead filler had a relatively small effect on the perforation process. Predictions from a cylindrical cavity-expansion model for the hard steel core projectiles are shown to be in good agreement with measured ballistic-limit and residual velocity data. The results of this study complement our previous paper with 5083-H116 aluminum target plates in that the ultimate tensile strength of 7075-T651 is about 1.8 times greater than that of 5083-H116. We also present a scaling law that shows a square root relationship between ballistic-limit velocity and plate thickness and material strength. [ABSTRACT FROM AUTHOR]

We conducted an experimental and analytical study to understand the mechanisms and dominant parameters for ogive-nose rods and 7.62 mm APM2 bullets that perforate 5083-H116 aluminum armor plates. The 20-mm-diameter, 95-mm-long, ogive-nose, 197 g, hard steel rods were launched with a gas gun to striking velocities between 230–370 m/s. The 7.62-mm-diameter, 10.7 g, APM2 bullet consists of a brass jacket, lead filler, and a 5.25 g, ogive-nose, hard steel core. The brass and lead were stripped from the APM2 bullets by the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel cores. These projectiles were fired from a rifle to striking velocities between 480–950 m/s. Targets were 20, 40, and 60-mm-thick, where the 40 and 60-mm-thick targets were made up of layered 20-mm-thick plates in contact with each other. The measured ballistic-limit velocities for the APM2 bullets were 4, 6, and 12% smaller than that for the hard steel cores for the 20, 40, and 60-mm-thick targets, respectively. Thus, the brass jacket and lead filler had a relatively small effect on the perforation process. In addition, we conducted large strain, compression tests on the 5083-H116 aluminum plate material for input to perforation equations derived from a cavity-expansion model for the ogive-nose rods and steel core projectiles. Predictions for the rod and hard steel core projectiles are shown to be in good agreement with measured ballistic-limit and residual velocity data. These experimental results and perforation equations display the dominant problem parameters. [ABSTRACT FROM AUTHOR]

The article presents a study examining the behavior of aluminum plates under ballistic impact. It states that 1,100 one-millimeter (mm)-thick aluminum plate undergone experimental ballistic impact tests with different projectile nose shapes in the Product Safety Laboratory, and finite element method and regression analysis were applied in numerical investigation. Results showed a good correlation between residual velocity in computer simulation and failure modes in the experiment.

This paper considers two independent methods for measuring the transient burning rate of solid propellants-high-speed photography and a method based on solving the inverse problem of interior ballistics. Comparative analysis shows that these methods are mutually complementary. Evaluation of the ranges of application of the inverse methods of identifying the transient burning rate shows that their use is promising not only in laboratory tests but also in measurements in large solid propellant gas generators. [ABSTRACT FROM AUTHOR]

This paper presents the results of measurements of the transient burning rate of homogeneous and model composite solid propellants during sudden depressurization of a semi-enclosed volume using two independent methods - high-speed photography and a method based on solving the inverse problem of interior ballistics. A comparative analysis of the results shows that the methods are mutually complementary. [ABSTRACT FROM AUTHOR]

An engineering analysis of computing the penetration problem of a steel ball penetrating into fibre-reinforced composite targets is presented. Assume the metal ball is a rigid body, and the composite target is a transversely isotropic elasto-plastic material. In the analysis, a spherical cavity dilatation model is incorporated in the cylindrical cavity penetration method. Simulation results based on the modified model are in good agreement with the results for 3-D Kevlar woven (3DKW) composite anti-penetration experiments. Effects of the target material parameters and impact parameters on the penetration problem are also studied. [ABSTRACT FROM AUTHOR]

Over last few decades, Al-based metal matrix composites (MMCs) have become a promising material of choice for lightweight armors in vehicles. Recent development in ultra-fine-grain and nanostructured material technology provides a new opportunity for the substantial strength enhancement of MMCs unattainable with the conventional microstructure of microscale, leading to significant weight reduction in armor packages. In this article, we will present the latest development of a novel class of nanostructured metal matrix composites (NMMCs) based on submicron SiC particulates reinforced nanocrystalline Al alloys. The successful fabrication of large-dimension NMMCs plates with a cost-effective synthesis and consolidation process that can be scaled up for mass production will be demonstrated. The microstructure, processing, mechanical properties, and their correlations of this class of NMMCs will also be reported. The ballistic performance of the NMMCs is investigated through a real test of high-speed machinegun bullets, and a numerical modeling as well. [ABSTRACT FROM AUTHOR]

We present the results of comprehensive experimental and theoretical investigations of encounter with a barrier of a group of bodies thrown with a high-velocity. Throwing of a group of particles (from two to twelve bodies) was realized on a ballistic route using powder and light-gas units of different calibers in the range of velocities 500–3500 m/s. The process of particle throwing was controlled by acting aerodynamic forces. In experiments on collisions with barriers of a finite thickness (which imitates the protective shield of spacecraft) the number of particles in a homogeneous stream was varied from 2 to 7 at changing the flux density (distances between particles). Experimental data are obtained on variations of the area and mass of back-surface splinters. Numerical calculations simulated a knock of 2 to 4 particles against a barrier in the cases of normal impact and at an angle. The calculations were performed in three-dimensional formulation and applying criteria of complete destruction of material. The appearance of additional destruction centers in the barrier due to mutual influence of particles is revealed. Simple criteria are obtained for estimating the degree of interference of particles and the character of barrier destruction. [ABSTRACT FROM AUTHOR]

Ballistic injuries to head-neck and maxillofacial region is quite common problem nowadays. Most of the time the injuries seem to be dreadful but the mechanism of the injuries caused by ballistics and the anatomical conditions of maxillofacial and head-neck region mitigate the severity of the injuries. Proper primary management followed by reconstruction and management of associated injuries decreases the mortality and morbidity of missile injuries in head-neck and maxillofacial region. Eleven cases of missile injuries in head-neck and maxillofacial region are included in the present study. The mechanism of the injury and the ideal management strategy for the ballistics injuries in the region has been discussed in the article. [ABSTRACT FROM AUTHOR]

The paper is devoted to studying the motion of meteor bodies with mass outflow in a planet’s atmosphere, taking into account the non-isothermal character of the latter. Analytical solutions are obtained at the constant parameter of mass outflow in the model of a nonfragmenting meteoroid. A theoretical analysis of the derived regularities of the ballistics of such bodies is presented. [ABSTRACT FROM AUTHOR]

Study design:Reviewing documents about Lord Admiral Nelson's wound inflicted at the Battle of Trafalgar and studying the collected data in connection with ballistics and human anatomy. Objectives:Attempting to find out the actual cause of death of Lord Nelson as soon as 4 h postinjury by a musket ball. Setting:United Kingdom. Methods:(1) Review of the original report of Mr W Beatty, Lord Nelson's surgeon, on his examination of His Lordship's wound. (2) Investigating the course of the musket ball in connection with an atlas of human anatomy. (3) Investigating the course of the musket ball on a cadaver by RP (one of the authors). (4) Reviewing modern medical literature. Results:The report of Mr Beatty suggested that division of a large branch of the pulmonary artery was the cause of Lord Nelson's early death. Assuming the left pulmonary artery was injured, anatomical studies based on atlases and dissection on a cadaver failed to support a simple straight-line course of the musket ball that could have divided the artery and damage the spinal cord on its path forward. Conclusion:The question remains open as to how the musket ball following a relatively straight-line trajectory by entering the body at the acromion, could have divided the left pulmonary artery and damaged the spinal cord later in its course. The mechanism needs further investigation. [ABSTRACT FROM AUTHOR]

The exploitation of rocket guidance technology on the basis of the guidance law of Space Shuttle and Pegasus rocket was performed. A new efficient method of numerical iteration solution to the boundary value problem was put forward. The numerical simulation results have shown that the method features good performances of stability, robustness, high precision, and algebraic formulas in real computation. By virtue of modern DSP ( digital signal processor) high speed chip technology, the algorithm can be used in real time and can adapt to the requirements of the big primary bias of rocket guidance. [ABSTRACT FROM AUTHOR]

Modern air-nailing tools are known to cause penetrating trauma. We report the unusual case of a pneumatically fired carpenter's nail that penetrated the chest of a 30-year-old man and subsequently embolized from the heart to the left femoral artery without clinical evidence of having entered the heart. The nail was surgically removed, and the patient was discharged from hospital without sequelae after 10 days. This case and the relevant literature are discussed from the perspective of the emergency department investigation and care of such patients. [ABSTRACT FROM AUTHOR]

Discusses the monitored ballistic tests on shockproof sandwich glasses in different conditions. Assessment of the applicability of piezoelectric accelerometers; Components of the impulsive elastic tests; Analysis of strain gage and acceleration signals of sandwich glass.

Large pyroclasts—often called ballistic projectiles—cause many casualties and serious damage on people and infrastructures. One useful measure of avoiding such disasters is to numerically simulate the ballistic trajectories and forecast where large pyroclasts deposit. Numerical models are based on the transport dynamics of these particles. Therefore, in order to accurately forecast the spatial distribution of these particles, large pyroclasts from the 2015 Aso Strombolian eruptions were observed with a video camera. In order to extrapolate the mechanism of particle transport, we have analyzed the frame-by-frame images and obtained particle trajectories. Using the trajectory data, we investigated the features of Strombolian activity such as ejection velocity, explosion energy, and particle release depth. As gas flow around airborne particles can be one of the strongest controlling factors of particle transport, the gas flow velocities were estimated by comparing the simulated and observed trajectories. The range of the ejection velocity of the observed eruptions was 5.1–35.5 m/s, while the gas flow velocity, which is larger than the ejection velocity, reached a maximum of 90 m/s, with mean values of 25–52 m/s for each bursting event. The particle release depth, where pyroclasts start to move separately from the chunk of magmatic fragments, was estimated to be 11–13 m using linear extrapolation of the trajectories. Although these parabolic trajectories provide us with an illusion of particles unaffected by the gas flow, the parameter values show that the particles are transported by the gas flow, which is possibly released from inside the conduit. [ABSTRACT FROM AUTHOR]

On 27 April 2016, White Island erupted in a multi-pulse, phreatic event that lasted for ~ 40 min. Six, variably sized pulses generated three ballistic ejections and at least one pyroclastic surge out of the inner crater and onto the main crater floor. Deposit mapping of the pyroclastic surge and directed ballistic ejecta, combined with numerical modelling, is used to constrain the volume of the ejecta and the energetics of the eruption. Vent locations and directionality of the eruption are constrained by the ballistic modelling, suggesting that the vent/s were angled towards the east. Using these data, a model is developed that comports with the field and geophysical data. One of the main factors modifying the dispersal of the eruption deposits is the inner crater wall, which is ~ 20 m high. This wall prevents some of the pyroclastic surge and ballistic ejecta from being deposited onto the main crater floor but also promotes significant inflation of the surge, generating a semi-buoyant plume that deposits ash high on the crater walls. While the eruption is small volume, the complexity determined from the deposits provides a case study with which to assess the relatively frequent hazards posed by active volcanoes that host hydrothermal systems. The deposits of this and similar eruptions are readily eroded, and for complete understanding of volcanic hazards, it is necessary to make observations and collect samples soon after these events. [ABSTRACT FROM AUTHOR]

Conflict damage to heritage has been thrust into the global spotlight during recent conflict in the Middle East. While the use of social media has heightened and enhanced public awareness of this ‘cultural terrorism’, the occurrence of this type of vandalism is not new. In fact, as this study demonstrates, evidence of the active targeting of sites, as well as collateral damage when heritage is caught in crossfire, is widely visible around Europe and further afield. Using a variety of case studies ranging from the 1640s to the 1930s, we illustrate and quantify the changing impact of ballistics on heritage buildings as weaponry and ammunition have increased in both energy and energy density potential. In the first instance, this study highlights the increasing threats to heritage in conflict areas. Second, it argues for the pressing need to quantify and map damage to the stonework in order to respond to these challenges. [ABSTRACT FROM AUTHOR]

A laboratory gun that uses compressed gas as its propellant was designed and tested for the study of small projectiles traveling in soils with initial velocities ranging from 50 to 200 m/s. The gun employed the use of air or helium with an electrically triggered, pneumatically piloted, solenoid valve. The triggering system was designed to provide remote activation. A photo gate speedometer was utilized to measure the exit velocity of each projectile. Details of the electro‐pneumatic control system are presented in this paper along with the design of the gun assembly and its subsystems. The effects of different design parameters, including muzzle length, projectile mass, propellant type, and volume of compressed gas utilized, on projectile velocity were investigated. Statistical analysis of the gun performance is presented. The gun is currently being used to visualize the fundamental physics of rapid earth penetration in soils, using transparent soils. [ABSTRACT FROM AUTHOR]