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Application of a shear-thickening-fluid treatment to neat Kevlar has been reported to improve fabric ballistic performance for impacts of 0.22-caliber-fragment-simulating projectiles at velocities near 800 fps. In recent research, the authors have evaluated the ballistic performance of shear-thickening-fluid Kevlar in a series of impact experiments performed using larger projectiles and thicker targets at impact velocities near 1000 fps, including two different fabric boundary conditions. The experimental results indicate that, under these test conditions, the impact protection afforded by shear-thickening-fluid Kevlar is, at best, equivalent to that provided by neat Kevlar at the same areal density. In addition, the ballistic performance of shear-thickening-fluid Kevlar was found to be strongly dependent on fabric-target boundary conditions, with the best performance obtained in a friction-sensitive target configuration that is not representative of current body armor, orbital debris shielding, or fan-blade containment systems. [ABSTRACT FROM AUTHOR]

Abstract: An analytical model has been developed in this paper for perforation of ceramic/multi-layer woven fabric targets by blunt projectiles. In previous Chocron–Galvez analytical model the semi-angle of ceramic conoid is constant and the strain rate effects are also neglected in the stress–strain behavior of the yarns and only strain energy absorbed by the yarns is considered. In this paper which is an improvement to the Chocron–Galvez analytical model for modeling the fragmented ceramic conoid, the Zaera–Sanchez-Galvez analytical model has been used and the semi-angle of ceramic conoid has been modified. For modeling the back-up woven-fabric material and deformation of yarns during perforation, the kinetic and strain energy of yarns has been determined. In the stress–strain relation of yarns, the effect of the strain rate is considered. Furthermore, a failure model based on the energy absorbed until failure by woven fabric is also used. Residual velocity, velocity–time history of projectile, residual mass of fragmented ceramic conoid, penetration depth until failure of yarns and energy absorbed by woven fabric are all estimated by new analytical model. Velocity–time history of the projectile shows a good agreement with the Chocron–Galvez numerical model. Also, near the ballistic limit velocity, prediction of residual velocity of new model is better than Chocron–Galvez analytical model. [ABSTRACT FROM AUTHOR]

The performance of 7.62×54r BS32 armour-piercing incendiary (API) projectiles against ceramic-faced armour is investigated in trials for yawed impacts. Controlled yaw of the projectile was induced by chamfering the rear of the projectile, producing strong asymmetric lift forces on the tail of the round during the intermediate ballistics phase. High-speed video recorded yaw in two orthogonal planes immediately before impact. Projectile yaw varied in a sinusoidal manner at approximately 3.5m wavelength with a maximum of 8-14° at approximately 10m from the muzzle. Logistic regression was used to determine the penetration probability curve and V50 ballistic limit velocity which was found to be 735 ms-1 for the un-yawed projectiles but only 685 ms-1 for the yawed projectiles. [ABSTRACT FROM AUTHOR]

The integration of a high-hardness steel armor plate inside the bodywork of a vehicle may result in a decrease in the overall ballistic resistance. This phenomenon is referred to as the bodywork effect. The effect was examined for a 5.56 × 45 mm North Atlantic Treaty Organization (NATO) Ball projectile. Previously reported experimental work has confirmed the numerically based assumption that the bodywork effect was due to the flattening of the tip of the projectile upon perforation of the frontal bodywork plate prior to hitting the integrated armor. The amount of qualitative and quantitative experimental data has now been extended. In order to eliminate the data dispersion observed after perforating the bodywork, an adapted projectile geometry with a truncated nose was fired directly against the armor plate. Ballistic testing also involved firing a soft-core 5.56 × 45 mm projectile for which a similar mechanism was observed. A finite element code was used to simulate the impact process for the different types of projectiles. The parameters of the selected strength and failure models were experimentally determined for the high-hardness armor plate. As to the ballistic limit velocity and plugging morphology there is a good correspondence between the experimental and computed results. Nevertheless, an improved failure model is necessary to get satisfactory computed residual projectile velocities. [ABSTRACT FROM AUTHOR]

Rarefaction wave gun (RAVEN) propulsion has renewed interest in the fundamental limits of recoil reductions attainable by redirecting propellant gases rearward from a gun without compromising the projectile propulsion. Compared with a conventional gun there is a great difference in the launch process and launch structure. This paper is concerned with an analysis of the dynamic characteristics of this high performance weapon system by numerical simulation. Based on its launch mechanism and launch structure, the vibration equation describing the vibration characteristics of RAVEN was established by vibration theory, which considered the actual movement of the projectile and inertial breech by coupling the interior ballistic equations of the rarefaction wave gun. A rigid-flexible dynamic model, which considered the coupling effect between the elastic vibration of the launch barrel and the dynamic behaviors of the other parts of the RAVEN, is established via a subsystem method. The vibration response of RAVEN during the launch is analyzed by numerical simulation. Comparisons are presented based on the conventional gun, as well as the rules of how the different parameters affect the vibration response. During the launching of RAVEN, the launch barrel shows significant vibration due to the effect of the propellant gases, the inertial breech, and the projectile, and there is some reduction in the vibration amplitude compared with that observed in a conventional closed chamber gun. The vibration amplitude and duration of the launch barrel, which increased with a decrease in the loading density, an increase in the mass of the inertial breech and projectile, and a delay of the venting time, is affected in a more significant manner by changes in loading density and the mass of projectile. The coupled effect between the launch barrel and the other parts of RAVEN are most prevalent in the z-direction. The vibration amplitude along the z-direction is higher than that of the y-direction. When the coupled effect is considered, the transverse vibration response of the flexible barrel has some reduction compared with the one that does not exhibit the coupling effect. [ABSTRACT FROM AUTHOR]

The U.S. Army uses several types of tests to increase the reliability of gun-fired munitions. Systems, subsystems, and components are gun fired to assess reliability. When failures are found, root-cause investigations are completed and parts may be redesigned. For in- stance, the 155 mm projectile Excalibur uses several types of tests to find failures and build reliability. Components are tested in a rail gun, a new soft-catch gun, and in soft recovery vehicles. With the rail gun, test projectiles are fired from a worn gun tube into a trough of water The soft-catch gun, a hybrid system using both air and water, has a standard cannon tube and a series of catch tubes to stop a projectile. The third type of test, a soft recovery vehicle, uses a modified tactical Excalibur with a parachute for a soft landing. All three types of tests have on-board recorders to capture ballistic accelerations. Accelerometer data are used in failure investigations, redesign parts, and to design new projectiles. The purpose of this paper is to compare accelerations from different types of ballistic tests. Comparisons were done to determine if the tests were in the same statistical family. Comparisons are made for a United States MACS 5 charge. The maxi- mum axial forces were the same for the soft-catch gun and the soft recovery vehicle. In the balloting directions, the rail gun and soft recovery vehicle had similar forces. The set forward forces differed in all three cases, reflecting the different catch mechanisms for the projectiles. Comparisons of g-forces were also made using shock response spectra. The shock response indicated that the damage potential is greatest for the rail gun tests, consistent with an increase rate of failures for some electronics. [ABSTRACT FROM AUTHOR]

Abstract: A method combining photogrammetry with ballistic analysis is demonstrated to identify flying debris in a rocket launch environment. Debris traveling near the STS-124 Space Shuttle was captured on cameras viewing the launch pad within the first few seconds after launch. One particular piece of debris caught the attention of investigators studying the release of flame trench fire bricks because its high trajectory could indicate a flight risk to the Space Shuttle. Digitized images from two pad perimeter high-speed 16-mm film cameras were processed using photogrammetry software based on a multi-parameter optimization technique. Reference points in the image were found from 3D CAD models of the launch pad and from surveyed points on the pad. The three-dimensional reference points were matched to the equivalent two-dimensional camera projections by optimizing the camera model parameters using a gradient search optimization technique. Using this method of solving the triangulation problem, the xyz position of the object''s path relative to the reference point coordinate system was found for every set of synchronized images. This trajectory was then compared to a predicted trajectory while performing regression analysis on the ballistic coefficient and other parameters. This identified, with a high degree of confidence, the object''s material density and thus its probable origin within the launch pad environment. Future extensions of this methodology may make it possible to diagnose the underlying causes of debris-releasing events in near-real time, thus improving flight safety. [Copyright &y& Elsevier]

Abstract: Depth of penetration experiments were conducted with fragment simulating projectiles launched into Celotex® in order to develop an equation for the strike velocity as a function of the FSP mass and the depth of penetration into Celotex® recovery media. A powder gun launched FSPs, designed in accordance with STANAG-2920 [NATO STANAG-2920 Ballistic Test Method for Personal Armour Materials and Combat Clothing, 2nd ed., 1999.] weighing between 0.13g and 53.78g at striking velocities between 198m/s and 1524m/s. A multiple linear regression analysis was used to determine an empirical relationship for the strike velocity to the impact parameters of depth of penetration, fragment mass, and mean presented area. Sabot launched natural fragments weighing between 2.8g and 15.8g at striking velocities between 532m/s and 1084m/s were used to validate the equation. [Copyright &y& Elsevier]

Transverse motion of a projectile during launch is detrimental to firing accuracy, structural integrity, and/or on-board electronics performance of the projectile. One manifest contributing factor to the undesired motion is imperfect bore centerline straightness. This paper starts with the presentation of a deterministic barrel model that possesses both vertical and lateral deviations from centerline in accordance with measurement data, followed by a novel approach to simulating comprehensive barrel centerline variations for the investigation of projectile balloting^1 motions. A modern projectile was adopted for this study. In-bore projectile responses at various locations of the projectile while traveling through the simulated gun tubes were obtained. The balloting was evaluated in both time and frequency domains. Some statistical quantities and the significance were outlined. [ABSTRACT FROM AUTHOR]

This article deals with the perforation of ductile metal plates subjected to impact by flat-nosed projectiles at normal incidence. Generally speaking, ductile metal plates under impact by flat-ended missiles can fail either by global deformation combined with local shear rupture or by localized adiabatic shear plugging depending upon the geometrical and thermo-mechanical properties of both the targets and the projectiles. Modification is first made to the Bai-Johnson model for adiabatic shear plugging by taking account of strain rate effects using a thermo-viscoplastic constitutive equation instead of thermo-plastic material model and equations for the energy dissipated in the perforation process (perforation energy), the ballistic limit and the residual velocity are then obtained. Furthermore, a critical condition is obtained for differentiating localized adiabatic shear plugging from simple shear plugging failure with global deformations by comparing the modified Bai-Johnson model and the Wen-Jones model. It transpires that the present theoretical predictions are in good agreement with available experimental data in terms of the ballistic limits and the critical transition condition for the modes of plugging failure of ductile metal plates subjected to impact by flat-nosed missiles. It also transpires that the present model predicts well the residual velocities and the energies dissipated in the perforation process. [ABSTRACT FROM AUTHOR]

In the design of a military helicopter, with the aim to operate at low altitude into enemy territory, the damage of critical components, caused by ballistic impact, plays a primary role in assessing the survival of the entire machine. In this work an experimental study is proposed, concerning the capability of a helicopter to carry out a mission of return to the base at reduced power, in the presence of a tail rotor shaft damaged by ballistic impact of 7.62 NATO projectile. In the first part of this study, some specimen representatives of the tail rotor shaft are subjected to experimental ballistic impact tests. Subsequently, static and dynamic torsional tests have been performed on the damaged components in order to asses the residual strength under the loads encountered during the mission. [ABSTRACT FROM AUTHOR]

Abstract: We have studied the sequence of events that occurs when a high-speed projectile (from 960ms−1 to 1480ms−1) penetrates a vessel filled with toxic liquid. We find that prior to liquid ejection several well-defined phases occur, including the phenomenon known as the “hydraulic ram.” Then a catastrophic tank failure leads to liquid ejection and fragmentation. This paper focuses on this phenomenon and explains how it can be related to the initial conditions of the target. [Copyright &y& Elsevier]

Abstract: This paper presents the ballistic behavior and penetration mechanism of metal–metal and metal–fabric layered structures against 7.62armour piercing projectiles at a velocity of 840±15m/s at 30° angle of impact and compares the ballistic results with that of homogeneous metallic steel armour. This study also describes the effect of keeping a gap between the target layers. Experimental results showed that among the investigated materials, the best ballistic performance was attained with metal–fabric layered structures. The improvements in ballistic performance were analyzed in terms of mode of failure and fracture mechanisms of the samples by using optical and electron microscope, X-ray radiography and hardness measurement equipments. [Copyright &y& Elsevier]

Abstract: Various open-literature experimental findings pertaining to the ballistic behavior of glass are used to construct a simple, physically based, high strain-rate, high-pressure, large-strain constitutive model for this material. The basic components of the model are constructed in such a way that the model is suitable for direct incorporation into standard commercial transient non-linear dynamics finite-element based software packages like ANSYS/Autodyn [ANSYS/Autodyn version 11.0, User documentation, Century Dynamics Inc. a subsidiary of ANSYS Inc.; 2007.] or ABAQUS/Explicit [ABAQUS version 6.7, User documentation, Dessault systems, 2007.]. To validate the material model, a set of finite element analyses of the Edge-on-Impact (EOI) tests is carried out and the results compared with their experimental counterparts obtained in the recent work of Strassburger et al. [Strassburger E, Patel P, McCauley JW, Kovalchick C, Ramesh KT, Templeton DW. High-speed transmission shadowgraphic and dynamic photoelasticity study of stress wave and impact damage propagation in transparent materials and laminates using the edge-on impact method. In: Proceedings of the twenty-third international symposium on ballistics. Spain: April 2007, and Strassburger E, Patel P, McCauley W, Templeton DW. Visualization of wave propagation and impact damage in a polycrystalline transparent ceramic-AlON. In: Proceedings of the twenty-second international symposium on ballistics. Vancouver, Canada: November 2005.]. Overall, a good agreement is found between the computational and the experimental results pertaining to: (a) the front-shapes and propagation velocities of the longitudinal and transverse waves generated in the target during impact; (b) the front-shapes and propagation velocities of the “coherent-damage” zone (a zone surrounding the projectile/target contact surface which consists of numerous micron- and sub-micron-size cracks); and (c) the formation of “crack centers”, i.e. isolated cracks nucleated ahead of the advancing coherent-damage zone front. Relatively minor discrepancies between the computational and the experimental results are attributed to the effects of damage-promoting target-fixturing induced stresses and cutting/grinding-induced flaws located along the narrow faces of the target and the surrounding regions. [Copyright &y& Elsevier]

This paper describes theoretical and experimental work aimed at the development of a new class of high-speed projectiles with superior penetration performance. Our earlier publications were focused on the finite element analysis of projectile-target interaction over a wide range of impact speeds. The projectiles were made of tungsten or alumina, and the target plates were made of aluminum, steel, or tungsten. Subsequently, finite element modeling was performed for ceramic rods encased in metal shells and launched against reinforced concrete. This paper expands the range of ceramic and ceramic-based composite materials for use in high-speed projectiles. Materials were compared based on their mass density, Hugoniot elastic limit, fracture toughness, deformability, and ability to withstand intense aerodynamic heat during high-speed flight and penetration. Finite element analysis was performed for ceramic and tungsten projectiles impacting metal plates at speeds ranging from 0.5 to 6.0 km/s. Several transient phenomena such as ceramic projectile self-sharpening, multiple impacts, spall, and buckling were observed. The computation results were used for the design and manufacture of high-speed projectiles with superhard tips made of commercially available diamond composites. Experiments involved several projectile configurations. The penetration depth of reference steel projectiles into concrete decreased with increased impact speed, while the penetration depth of the projectiles with diamond tips increased. Clusters of ceramic and metal-ceramic projectiles and fragments can find use against larger and softer targets and in the generation of debris. [ABSTRACT FROM AUTHOR]

Active electromagnetic (EM) armor is a new type of active defense system, which can intercept invading objects effectively. When hit by interception projectiles, the invading object will deviate from its trajectory or be destroyed totally. A steerable EM launcher system using two separate pancake coils is introduced in this paper, and its 3-D model is built. With finite element analysis code, acceleration process of the interception projectile is simulated, and laws of acceleration force acting on the projectile, its velocity, and displacement versus time are also investigated. Experimental installation is introduced, and experimental data are well matched with simulation results. [ABSTRACT FROM AUTHOR]

This paper deals with experiments and calculations performed in order to investigate the influence of the electromagnetic hardening of payloads in a railgun. This is a complex task: besides the large amplitudes of the in-bore magnetic fields due to the pulsed current, the exit of the projectile from the muzzle and the consequences of plasma arcs have to be considered. At the muzzle the magnetic induction can drop from several Teslas to zero within some microseconds, leading to very high induced voltages and electric fields in the metallic parts of the projectile. On the other hand, the electric contact established by solid armatures tends to develop into electric arcs at high velocities during the launch. These plasma arcs as well as the closing switch transients of the railgun circuit are a source of electromagnetic radiation in a broad spectral range. Some electronic devices were selected and tested with static setups corresponding to the previous conditions. In a first phase a series of static railgun experiments (no projectile movement) was performed. In a second phase, static experiments simulating the muzzle exit conditions were carried out. Finally, the influence of electromagnetic waves emitted during railgun experiments on electronic devices was investigated, using a static setup with a conventional spark gap. [ABSTRACT FROM AUTHOR]

Projectiles in coil gun usually make one-way movement and move at a very high speed. The device would be fit for the application of oil pumping unit, as long as the projectiles can make reciprocating movement and move slower by adopting proper control methods. At present, during the production process of petroleum, the efficiency of the system is rather low. Energy dissipation takes a considerable ratio in the total cost of oil production. Moreover, beam pumping-unit system suffers from long driving chain, poor flexibility, a quite huge capacity and weight under long length of stroke, and low efficiency. Aiming at the earlier problems, linear electromagnetic oil pumping unit is presented in this paper, which is essentially a multiphase coil launcher. Analysis is made about the advantages and disadvantages of three~phase and multiphase structures, as well as the practical structure. Simulation studies are made; meanwhile, experimental investigations are carried out on a small-scale-model machine system. Further simulation studies of coil launching system are carried through the mechanical and mathematical models of rod string in a sucker-rod pumping-unit system. Theoretical analysis and experimental results verify the feasibility and the validity of the proposed system. Thus, a new path to solve the problem of high energy dissipation in oil production is explored. [ABSTRACT FROM AUTHOR]

Abstract: The testing methodology for transparent armour is described. The focus of this paper is on the assessment of the protective strength of transparent ceramics being used in transparent armour systems. Not only the ballistic testing method but also experimental techniques which allow the visualization of damage and the projectile penetration are discussed. Visualization techniques are essential for understanding the mechanisms of interaction between projectile and target material. Ballistic tests results, high-speed photographs and flash-radiographs from experiments with transparent armour are presented. [Copyright &y& Elsevier]

The interaction between a projectile and metal-matrix composites (MMCs) was investigated in terms of macro cracking, petalling and particularly grain deformation of a matrix alloy at the hole section caused by the projectile at high velocity impact. Metal matrix composites were manufactured by squeeze casting using Al alloys reinforced with Al2O3 or SiC. Additionally, laminated composites with SiC particles and back side supported by Kevlar 49® were manufactured and their ballistic behavior tested. The composite and unreinforced Al alloy targets were subjected to ballistic impact with an armor piercing projectile of 7.62mm caliber at a speed in the range of 770-800 m/s. The macro examination focused on cracking and petalling after impact. The investigation of grain deformations of matrix alloy was conducted by light microscopy in the hole section created by the projectile. The hole section created by the projectile had different profiles. Around the hole sections, different grain deformation rates in different directions took place for reinforced and unreinforced Al alloys. Strong friction took place between the projectile and hole surface and the velocity of the projectile was decreased suddenly in the hole as it met the reinforcement particles in the composite body. These led to deformations of the projectile surface and grain surrounding the reinforcement. In the case of laminate composites, the laminates were fractured and deformed in the direction of projectile movement [ABSTRACT FROM AUTHOR]

Abstract: We present penetration equations for rigid, ogive-nose, rod projectiles that penetrate aluminum targets at normal impact. Comparisons of depth of penetration data and predictions from a previously published penetration equation derived from spherical, cavity-expansion methods show excellent agreement for striking velocities to 1800m/s. We then identify a small parameter in the penetration equation, perform a power-series expansion, and obtain approximate penetration equations. These approximate equations are very accurate for striking velocities to 1300m/s and display clearly the dominant problem parameters. [Copyright &y& Elsevier]

Abstract: A series of experiments are carried out to explore the impact characteristics of stiffened plates struck by the sub-ordnance velocity projectiles. Considering the relative position of impact point to the nearest stiffeners on target, six kinds of representative target plates with different stiffened styles are specially designed. Altogether sixteen target plates, respectively without, single- and cross-stiffened are tested and compared. Two kinds of projectiles, one with spherical nose and the other with truncated oval nose, are fired using a 25 mm refitted cannon. The initial velocities of projectiles range from 244 to 430 m/s. Experimental results show that the penetration process is greatly dependent on the nose shapes of projectiles. The tumbling of truncated oval-nosed projectiles is very prominent, which results in the great uncertainty of deformation and failure mode of target plates. While the spherical-nosed projectiles keep much more stable, plugging and ductile hole enlargement are the most distinct failure modes. In the end, some empirical formulas aimed at blunt-nosed projectiles are proposed, which could be helpful for the design of the protection structures. [Copyright &y& Elsevier]

This study evaluates the abilities of the Integrated Ballistics Identification System (IBIS) and BulletTRAX-3D electronic imaging systems to identify bullets fired by the same weapon in a large database of images. Ten consecutively rifled handgun barrels were test fired to obtain reference sample and known match sample pairs for upload onto both bullet acquisition systems. Both copper-jacketed and lead bullets were uploaded, to account for variations in the manner in which markings are reproduced on the different metal compositions. Ranked correlation lists were examined and evaluated. For copper-jacketed bullet correlations, both IBIS and BulletTRAX-3D identified all reference samples to their known matches within the top 10 positions. For lead bullets, BulletTRAX-3D identified all reference samples to their known match in the top 10 positions while IBIS identified only 30%. For inter composition comparisons, BulletTRAX-3D was more successful than IBIS, identifying 100% of reference samples to their known match in the top 20 for copper-jacketed to lead comparisons and 90% for lead to copper-jacketed comparisons. These results suggest that BulletTRAX-3D is more effective than IBIS in the analysis of a wider range of bullet types and it was also found to produce images of superior quality. [ABSTRACT FROM AUTHOR]

In this paper, three types of projectiles were designed, which are based on the physical mechanism of high-speed penetrating into concrete targets. The three types of projectiles are ogive nose followed by cylinder, cone and grooved cone shank respectively, which are made of 30CrMnSiNi2A with the yield strength 1570MPa. The unconfined compressive strength of concrete target for test is 50MPa. Seven experiments for striking velocities between 800 and 1100m/s were conducted. The experiments showed that the projectiles of cone and grooved cone shank have better penetration performances and the penetration channels were very straight. Compared with the cylinder shank projectiles, the cone and grooved cone shank projectiles are more effective under the condition of high velocity penetrating into complex geological materials as concrete or rock. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, a material model development approach and transient non-linear dynamics simulations of the projectile/armor interactions are employed to explore the role of multi-walled carbon-nanotube (MWCNT) reinforcements in improving the ballistic-protection performance of poly-vinyl-ester-epoxy matrix (PVEE)/E-glass fiber matrix reinforced laminate armor. Two different architectures of the composite-laminate armor are considered: (a) a hybrid armor consisting of a 100μm-thick high MWCNT-content PVEE-matrix MWCNT-reinforced lamina sandwiched between two PVEE-matrix/E-glass mat reinforced laminas and (b) a monolithic E-glass mat reinforced composite laminate with a low MWCNT-content MWCNT-doped PVEE-matrix. The projectile/armor interaction simulation results show that both armor architectures yield a minimal (∼6%) increase in the ballistic-protection as measured by the armor V50, a velocity at which the probability of armor penetration by a given fragment is 50%. The results obtained are rationalized using a simple analysis of the effect of MWCNTs on the in-plane and the through-the-thickness properties of the armor. [Copyright &y& Elsevier]

Abstract: In this research an armor material with constant thickness has been studied. The armor consists of two layers: one is a boron carbide ceramic and the other is Kevlar 49 fiber composite material. By using Ansys/Lsdyna software, the ballistic limit velocity of this armor has been obtained and the Heterington equation (optimum thickness of layers) has been verified for constant thickness of the armor. In this research, mechanical properties of Kevlar 49 under different strain rates are utilized and showed that consideration of the strain rate is very important for the simulation of penetration process. Results from the model have confirmed the validity of the Chocron–Galvez analytical model. Moreover, the projectile velocity prediction, especially at high velocity, shows a good agreement with numerical simulations. Finally, normal and oblique impacts of projectile to armor have been simulated and compared. The results show that the ballistic limit velocity of armor increases under oblique impact conditions. [Copyright &y& Elsevier]

Abstract: This paper examines the penetration and perforation of fibre-reinforced plastic (FRP) laminates struck by rigid projectiles with different nose shapes within a wide range of impact conditions using ABAQUS/Explicit code. It is assumed that the FRP laminate target response can be represented by a velocity dependent forcing function which eliminates discretizing the target as well as the need for a complex contact algorithm. The forcing function is then applied to the surface of the projectiles as boundary conditions in the numerical model. With this combined analytical and computational technique we can obtain the depth of penetration, residual velocity, ballistic limit, transient response in terms of time-histories of displacement/penetration, velocity and deceleration of the projectile. It is shown that the model predictions are in good correlation with available experimental data. [Copyright &y& Elsevier]

This paper put forward a method of reducing the armor-piercing projectile hit probability by investigating the characteristics of modern tank fire control system and armor-piercing projectile. A hit probability model based on traditional firing theory was established and analyzed. The results show that this method is effective. The further study points out that the most effective way to decrease the hit probability is reducing the response time of the target. [ABSTRACT FROM AUTHOR]

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Wood plates made from different types of wood have been impacted by three different kinds of projectile: 7.62mm bullet, 5.3mm ball and sharp fragment. Results of the ballistic testing are presented and discussed. Relation between ballistic resistance and density of wood is described and evaluated. The experimental results have been described in terms of a simple analytical model. [ABSTRACT FROM AUTHOR]

Ballistic impact tests were conducted using hard steel cylindro-conical projectiles of mass ranging between 550 to 570gms with three nose geometries against unidirectional glass-fiber reinforced epoxy composite plates of varying stacking sequence and thickness. Gas gun projectile launcher setup was used to accelerate the projectiles. The damage evolution, failure pattern, ballistic limit and energy absorption by each target set were determined experimentally. Experimental study shows that the nose geometry of heavy projectile has very less influence on the energy absorption and ballistic limit for thin targets whereas it plays a major role with increasing thickness of the laminates. It was also confirmed from the experimental study that delamination was not a major failure mechanism for thin laminates but has considerable effect on thick laminates. Severe delamination and damage were observed in thick laminates. Varying the stacking sequence neither showed marked deviation in ballistic limit nor energy absorption, but showed difference in delaminated area especially in thick targets. Results show that, while the amount of energy absorbed by the composite was different for all three projectiles, they showed similar trends - energy absorbed increased with velocity up to a critical impact velocity before it starts to decrease. A mathematical model based on energy balance principle and resistive forces acting on the projectile during perforation was developed to theoretically calculate the ballistic limit. The theoretical value correlates well with the experimental value. [ABSTRACT FROM AUTHOR]

The present article deals with the development of a finite element modelling approach for the prediction of residual velocities of hard core ogival-nose projectiles following normal impact on mild steel target plates causing perforation. The impact velocities for the cases analysed are in the range 818-866.3 m/s. Assessment of finite element modelling and analysis includes a comprehensive mesh convergence study using shell elements for representing target plates and solid elements for jacketed projectiles with a copper sheath and a rigid core. Dynamic analyses were carried out with the explicit contact-impact LS-DYNA 970 solver. It has been shown that proper choice of element size and strain rate-based material modelling of target plate are crucial for obtaining test-based residual velocity. The present modelling procedure also leads to realistic representation of target plate failure and projectile sheath erosion during perforation, and confirms earlier observations that thermal effects are not significant for impact problems within the ordnance range. To the best of our knowledge, any aspect of projectile failure or degradation obtained in simulation has not been reported earlier in the literature. The validated simulation approach was applied to compute the ballistic limits and to study the effects of plate thickness and projectile diameter on residual velocity, and trends consistent with experimental data for similar situations were obtained. [ABSTRACT FROM AUTHOR]

The hydrodynamic operation of the “Forest Flyer” type of explosive launching system for shock physics projectiles was investigated in detail using one and two dimensional continuum dynamics simulations. The simulations were numerically converged and insensitive to uncertainties in the material properties; they reproduced the speed of the projectile and the shape of its rear surface. The most commonly used variant, with an Al alloy case, was predicted to produce a slightly curved projectile, subjected to some shock heating and likely exhibiting some porosity from tensile damage. The curvature is caused by a shock reflected from the case; tensile damage is caused by the interaction of the Taylor wave pressure profile from the detonation wave with the free surface of the projectile. The simulations gave only an indication of tensile damage in the projectile, as damage is not understood well enough for predictions in this loading regime. The flatness can be improved by using a case of lower shock impedance, such as polymethyl methacrylate. High-impedance cases, including Al alloys but with denser materials improving the launching efficiency, can be used if designed according to the physics of oblique shock reflection, which indicates an appropriate case taper for any combination of explosive and case material. The tensile stress induced in the projectile depends on the relative thickness of the explosive, expansion gap, and projectile. The thinner the projectile with respect to the explosive, the smaller the tensile stress. Thus if the explosive is initiated with a plane wave lens, the tensile stress is lower than that for initiation with multiple detonators over a plane. The previous plane wave lens designs did, however, induce a tensile stress close to the spall strength of the projectile. The tensile stress can be reduced by changes in the component thicknesses. Experiments verifying the operation of explosively launched projectiles should attempt to measure porosity induced in the projectile: arrival time measurements are likely to be insensitive to porous regions caused by damaged or recollected material. [ABSTRACT FROM AUTHOR]

The ballistic impact failures and damages on metal matrix composites reinforced by SiC and alumina are studied. AA 6063 aluminum alloy is reinforced with SiC and alumina particles in different sizes and percentages by casting method. Ballistic tests are carried out by two different projectile types, AP (armor piercing) 7.62 and 9 mm. The macrography of the craters and holes created by high velocity projectiles impact are analyzed by light and scanning electron microscopy studies. The projectile type strongly influences the damage formation. When the high velocity projectile (AP 7.62, 7.9g, 710m/s) impacts the 30% SiC or Al2O3 reinforced composite, it leads to deep craters and then a hole by passing the thickness of the composite target thoroughly. Brittle cracking on the target and on the reinforcing particles are also observed after impact. If this impacting carried out on the composite is relatively tough (i.e., having 15% SiC), swelling and petalling on the entrance and back sides of the hole are also created without any cracking or breaking. In case of impacting by a lower velocity projectile (9 mm, 7.47 g, 400 m/s) on the 15% SiC composite target, it can pass the thickness with or without its jacket. This projectile cannot pass the composites reinforced by 30% SiC and Al2O3. Besides some damages such as plastic deformation and craters occur on the projectile tip. [ABSTRACT FROM AUTHOR]

The main motivation of this work is to clarify whether the hopes of significantly improving the performance of the conventional guns by using plasma ignition have a realistic basis. We assessed the possibility of improving the whole interior ballistic process, its repeatability and safety, through a uniform propellant ignition. In addition, we planed to improve the gun performance [the projectile muzzle energy (velocity)] by "forcing" "cold" charges to perform as "hot" ones (achieving "temperature compensation"). All of these goals are intended to be accomplished by using reasonable electrical energies (which would allow the reduction of the mass and volume of the power supply). We also avoided any significant changes in the conventional gun topography in order to prevent unacceptable costs. The presented research program proved that by using a standard 105-mm gun (concerning its barrel length and charge chamber volume) and a standard propellant, improved performances (more than 28% in the projectile muzzle energy) can be achieved while dense charges are used. In addition, significant reduction of the important effect, the "temperature gradient," is obtained. The capacity of plasma as the ignition factor to provide ballistic gain has also been demonstrated. [ABSTRACT FROM AUTHOR]

The three-year line of sight/beyond line of sight (LOS/BLOS) electrothermal chemical (ETC) launcher program, funded by the U.S. Army's Armament Research, Development and Engineering Center (ARDEC), Picatinny Arsenal, is a comprehensive effort to advance ETC launcher technologies. The program includes development of ETC plasma injectors for 120-mm M829A2s, build of a 100-kJ pulsed power supply small and robust enough to be realistically integrated into a combat vehicle, improvement of power connections to the gun to allow electromagnetic field containment and automated connection to the round, and tests of the completed ETC system with various chemical propellants and electrical energy levels. As part of the LOS/BLOS program, a new, coaxial version of BAE Systems' Basepad plasma injector has been developed and tested successfully in XM36, XM291, and M256 cannons. The Basepad's coaxial design effectively insulates the gun breech, thus preventing any part of the gun from being part of the high-voltage discharge circuit. A compact electrothermal ignition pulsed power supply (ETIPPS) has been designed, built, and tested. Including its own high-voltage charger, actuation circuitry, safety systems, and peripherals, ETIPPS's low weight and volume make it easily small enough for vehicle integration, as was demonstrated in a concurrent effort that included ETC firings from a combat vehicle. Test firings, currently ongoing, have validated the system architecture and performance and continue to supply data on performance at different temperatures, electrical energy levels, propellant loading, and propellant type. These tests demonstrate many of the benefits of ETC launchers including improved accuracy from precision ignition; maximum performance potential across all temperatures ranges (temperature compensation); and reliable ignition of new, high-energy, high-density, and in some cases low-vulnerability propellants. The system-wide approach of the LOS/BLOS electrothermal launcher program has advanced ETC technology significantly towards field readiness. [ABSTRACT FROM AUTHOR]

This article deals with a simulation-based study of the impact of projectiles on thin aluminium plates using LS-DYNA by modelling plates with shell elements and projectiles with solid elements. In order to establish the required modelling criterion in terms of element size for aluminium plates, a convergence study of residual velocity has been carried out by varying mesh density in the impact zone. Using the preferred material and meshing criteria arrived at here, extremely good prediction of test residual velocities and ballistic limits given by Gupta et al. (2001) for thin aluminium plates has been obtained. The simulation-based pattern of failure with localized bulging and jagged edge of perforation is similar to the perforation with petalling seen in tests. A number of simulation-based parametric studies have been carried out and results consistent with published test data have been obtained. Despite the robust correlation achieved against published experimental results, it would be prudent to conduct one's own experiments, for a final correlation via the present modelling procedure and analysis with the explicit LSDYNA 970 solver. Hence, a sophisticated ballistic impact testing facility and a high-speed camera have been used to conduct additional tests on grade 1100 aluminium plates of 1mm thickness with projectiles of four different nose shapes. Finally, using the developed numerical simulation procedure, an excellent correlation of residual velocity and failure modes with the corresponding test results has been obtained. [ABSTRACT FROM AUTHOR]

Abstract: Protection effectiveness of an oblique metallic plate against a long rod projectile has been evaluated through a three-dimensional dynamic finite element computer program. The parameters considered in the simulations are the impact velocity, oblique plate thickness, gap distance between oblique plate and witness block, and obliquity. It was found that protection performance of an oblique plate was maximized in case that the ratio of line-of-sight (LOS) plate thickness to projectile diameter is around 2.0. This result may be used as a guide for the design of obliquely spaced armour structures against long rod projectiles. [Copyright &y& Elsevier]

Abstract: This paper describes a series of smooth particle hydrodynamics (SPH) simulations of tungsten cylindrical and spherical projectiles impacting steel bumper plates at different impact configurations. Comparisons of the destructive capabilities of the spherical and cylindrical projectiles for each impact configuration are presented. Cylindrical geometries were spatially rotated to cover a wide range of impact configurations. The incidence angle of the velocity vector and its magnitude were varied. A rational approach is proposed to quantify the level of damage inflicted on the bumper plates on each impact event. This damage measure is used to create a set of comparative damage matrixes for cylindrical and spherical projectiles that identify under which impact configurations a given geometry is more damaged than the other. [Copyright &y& Elsevier]

This paper is based upon the observation that, when a bullet is fired, it creates characteristic markings on the cartridge case and projectile. From these markings, over 30 different features can be distinguished, which, in combination, produce a ‘fingerprint’ for a firearm. By analyzing features within such a set of firearm fingerprints, it will be possible to identify not only the type and model of a firearm, but also each and every individual weapon just as effectively as human fingerprint identification. A new analytic system based on the fast Fourier transform for identifying projectile specimens by the line-scan imaging technique is proposed in this paper. This paper develops optical, photonic, and mechanical techniques to map the topography of the surfaces of forensic projectiles for the purpose of identification. Experiments discussed in this paper are performed on images acquired from 16 various weapons. Experimental results show that the proposed system can be used for firearm identification efficiently and precisely through digitizing and analyzing the fired projectiles specimens. [ABSTRACT FROM AUTHOR]

The development of lightweight armour systems for ballistic protection is under continuing attention of the manufacturers and users. A new design of the composite armour systems has been developed and ballistically tested. A new armour system consists of a ceramic plate, an intermediate ceramic–polymer layer and a polymer fibre lining as a backing material. The proposed composite armour systems prepared with a use of specially selected compositions of the intermediate layer promoting the absorption of the kinetic energy of projectiles provide adequate ballistic protection to National Institute of Justice (NIJ) level III and level IV, and they successfully withstand multiple hits. [ABSTRACT FROM AUTHOR]

A simple and high performance sabot separation technique which is useful even in about 10-m-long supersonic ballistic ranges has been developed. The normal in-flight sabot separation distance is vastly reduced by adding an addition tube with no diaphragm that may cause damage to the projectile. The launch tube of the ballistic range is subdivided to the acceleration, ventilation, and sabot separation sections. In the ventilation section, both the precursor shock wave driven by the sabot when coasting through the acceleration section and the driver gas is vented out to the dump chamber. In the sabot separation section, only the sabot experiences a great dragging pressure imbalance whereas the drag to the projectile is kept negligible. Initially, the whole system except for the driver gas chamber is connected without any diaphragm; the range operation is not accompanied by any high-speed impact among the sabot, diaphragm, and other related solid parts. The experimental environment can be kept clean. The influence of the muzzle blast is eliminated within a reasonably short distance from the muzzle because it delays owing to the ventilation section. Calibration experiments and the demonstration of flow visualization and boom measurement of supersonic flight were conducted using a 25 mm bore, Mach-2 ballistic range. [ABSTRACT FROM AUTHOR]

with all less-than-lethal weapons, the user is frequently left to estimate the optimum effective range of their weapon. Factory literature often exaggerates effective ranges and other features, which can be misleading and potentially dangerous in the deployment of the weapon. Using a modular combat shotgun and its three barrels, this study examined the accuracy of 12 gauge bean bag rounds in relation to barrel length. Accuracy was measured by point of impact and projectile spread in relation to the deviation from the point of aim. Our observations for the selected shotgun and bean bag rounds show that, at distances under 12 m (40 ft), the projectile was both accurate and reliable. At greater distances, both accuracy and reliability decreased. The 25 cm (10 in), 36 cm (14 in), and 46 cm (18 in) barrels can be used in close proximity from 3 m (10 ft)--15 m (50 ft) without a considerable loss of accuracy. This is of major significance as the use of shotguns during tactical room clearing is often limited by the length of barrel. These findings suggest that even the shortest length barrel tested would perform well if the targets are not engaged beyond 15 m (50 ft). Beyond this distance, the 46 cm (18 in) barrel is the most accurate performer and will reliably engage targets out to the maximum tested range of 24 m (80 ft). [ABSTRACT FROM AUTHOR]

The swerve response of fin- and spin-stabilized projectiles to control mechanism inputs is sometimes not intuitive. This paper seeks to explain the basic parameters that govern the swerve of projectiles excited by control inputs. By modeling the overall effect of a generalized control mechanism as a nonrolling reference frame force applied to a point on the projectile, general expressions for swerve are obtained in terms of basic vehicle parameters. These compact expressions are used to show that maximum swerve response for a fin-stabilized projectile is achieved when the force is applied near the nose of the projectile, whereas maximum swerve response for a spin-stabilized projectile is achieved when the force is applied near the base of the projectile. [ABSTRACT FROM AUTHOR]

This study evaluates the energy absorption, perforation and damage evolution created by cylindrical projectile of different nose geometries in woven roving mat/epoxy laminates with 0.45° orientation. A series of ballistic impact tests have been carried out on the laminate with projectile nose geometries representing hemispherical, conical, and conical with round nose and truncated tip. A gas gun projectile launcher set-up was employed to impact the target at different speeds. The damage pattern, perforation mechanism and ballistic limit for each type of projectiles have been studied. Truncated-nose projectile shows the highest ballistic limit while sharp-nose shows the lowest. A quasi-static punch test was carried out on targets with projectiles of above-mentioned nose geometries to assess the damage evolution at a constant strain rate. The maximum load required to cause perforation during punch test was noted for hemispherical-nose projectile. An in-depth layerwise analysis was carried out to analyse the damage in each layer. [ABSTRACT FROM AUTHOR]

Abstract: Metal foam projectiles are used to generate dynamic pressure–time histories representative of shock loading in water and air. A 1D plastic shock wave analysis is performed for a foam projectile impacting a free but rigid mass. It is shown that the pressure versus time pulse exerted on the mass and the shock arrest distance within the foam depend upon the ratio of foam mass to impacted mass, and upon the ratio of quasi-static to hydrodynamic strength of the foam. The theory is supported by two sets of experiments, one where Alporas foam impacts an instrumented Kolsky pressure bar, and one where the foam is fired at a free mass. It is demonstrated that the magnitude and duration of the pressure pulse can be controlled by suitable adjustment of the velocity, length and density of the foam projectile. [Copyright &y& Elsevier]

This paper presents an analytical model for studying the material failure in shear hinges formed during the dynamic plastic response of a circular plate under projectile impact. Analytic solutions for the ballistic perforation performance of a fully clamped circular plate struck by a blunt projectile are obtained. It takes into account both the global response (plate bending) and the localized shear. Based on the estimations of the shear strain and the size of shear hinge, condition for the initiation of an adiabatic shear band is formulated. The effectiveness of the present model is demonstrated by reasonable agreement between the theoretical predictions and the available experimental data for the perforation of Weldox 460E steel plates. [Copyright &y& Elsevier]

This paper investigates the response of flexible laminates to ballistic impacts by projectiles of various geometries, namely, flat-ended, hemispherical, ogival (CRH 2.5) and conical (30° half-angle) projectiles. The laminate of interest is Spectra Shield® comprising [0°/90°] extended chain polyethylene filaments embedded in a thermoplastic resin. Ballistic tests show that flat-ended projectiles cut the laminate through a shearing action, effectively punching a circular hole in the laminate whereas hemispherical projectiles perforate the laminates by stretching the Spectra filaments to failure resulting in a rectangular hole in the laminates. While the manner in which they are perforated are different, many similarities are observed in specimens perforated by flat ended and hemispherical projectiles such as the formation of a generator strip, the extent of delamination, the creasing of the laminate, tearing of the laminate at the edges, etc. Ogival and conical projectiles, on the other hand, perforate the laminates with minimal delamination and tearing of the specimens. Interestingly, the region of the specimens affected by the projectiles appears to increase in size instead of becoming more localised at higher impact velocities as often reported for most ballistic impacts events, including the ballistic perforation of woven fabric. This suggests flexible laminates are more effective in dissipating energy than woven fabric in the application of flexible armour. [Copyright &y& Elsevier]

An analysis of results of calculations and data of full-scale tests was conducted in the work, that confirmed a possibility of substantial increase of the ammunitions power owing to simple structural and technological modification of a bullet and cartridges as a whole, oriented to its application in regular arms. [ABSTRACT FROM AUTHOR]