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Ballistic impacts are a primary risk in both civil and military defence applications, where successfully predicting the dynamic response of a material or structure to impact crucial to the design of safe and fit-for-purpose protective structures. This study proposes a conditional Generative Adversarial Network (cGAN) architecture that can learn directly from available ballistic data and can be conditioned on additional information, such as class labels, to govern its output. A single Multi-Layer Perceptron (MLP) cGAN architecture is trained on a multi-class ballistic training set consisting of 10 classes labelled 0 − 9 where each class refers to a ballistic curve with a different ballistic limit velocity, v bl. A total of 5 models are trained on datasets consisting of 5, 10, 15, 20 and 25 samples within each class. For integer class labels 0 − 9 , all cGAN models successfully predict the v bl with a maximum error of 4.12%. Additionally, for non-integer class labels between 0 − 9 the v bl predictions are similar despite not explicitly appearing in the training set. Moreover, each cGAN model is challenged to generate new samples for class labels that exist beyond the scope of the training set for class labels between 9 − 20. Four of the models predict the v bl with an error of less than 1.5% in all cases. This study showcases how a cGAN model can learn directly from a multi-class ballistic dataset and generate additional samples representative of that data for classes that do not appear explicitly in the training set. • Conditional Generative Adversarial Networks (cGAN) learn from multi-class datasets. • Paper proposes a unique solution to minimising cost of armour testing and design. • Method predicts ballistic impacts generating accurate ballistic curves. • Proposed cGAN method accurately predicts classes outside the training set. [ABSTRACT FROM AUTHOR]

The last five decades have seen strong developments in irrigation modeling. In solid-set sprinkler irrigation, models have generally been applied to a few sprinklers in a regular arrangement, making them representative of a sector or a field. In this research, the Ador-Solid-Set model for whole-field solid-set sprinkler irrigation is presented, validated and applied to simulate an irrigation event in two fields: CA (10.2 ha) and ZA (24.5 ha), equipped with 12 and 26 sectors, respectively. The model couples pipeline hydraulics (EPANET), sprinkler ballistics and irrigation scheduling at execution time. Field experiments were used to validate the ballistic model in a solid-set combining full- and partial-circle sprinklers. Observed and simulated irrigation depths and coefficients of uniformity showed determination coefficients of 0.73*** and 0.89***, respectively. Optimization was used to estimate pipeline roughness based on pairs of pressure measurements (at the inlet and specific sprinklers): 26 pairs in CA and 58 pairs in ZA. Roughness parameters were estimated for the main pipeline, each sector and the sprinkler risers: 14 parameters in CA and 28 in ZA. More than a million hydraulic simulations were required to estimate roughness in each field. Maps were produced for applied water in CA and ZA following a sequential irrigation of their sectors lasting for 24 hours. The model produced whole-field coefficients of uniformity of 80.2 in CA and 80.9 in ZA. Finally, Ador-Solid-Set quantified the volume of drift outside the field (2.4 and 1.5% of the applied water in CA and ZA, respectively). This additional drift can be added to the wind drift and evaporation losses obtained from empirical equations, in a process that requires further analysis. Research efforts are also needed to enhance the current model capabilities and address the challenges related to water quantity and quality in sprinkler solid-sets. • A solid-set irrigation model has been presented, calibrated and validated. • The model has been applied to two solid-sets of 10.2 and 24.5 ha. • New thresholds may be required for whole-field Irrigation uniformity. • The model quantified drift outside the computational domain. [ABSTRACT FROM AUTHOR]

Polyurea (PU) elastomers have become increasingly popular in recent years due to their exceptional blast mitigation, ballistic protection, and wear resistance properties. However, their applications as protective materials are often limited as a result of their high flammability. In this study, aromatic dianhydrides (ArDAs) were employed to capture the thermal decomposing products of PU during combustion and facilitate the generation of highly heat-resistant aromatic polyimides (i.e., end group capturing effect), thus enhancing the material's char-forming ability and improving its flame retardancy. The ArDAs were found to significantly reduce the peak heat release rate (PHRR), total heat release (THR), total smoke release (TSR), and total CO release (TCO) of PU, and meanwhile increased the amount of char residue. At 20 wt% content of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), PHRR, THR, TSR and TCO of PU were reduced by 70.6%, 32.5%, 44.7% and 58.8%, respectively, the char residue was increased by 405%, and the mechanical properties of PU were well maintained (88.5% tensile strength and 91.0% elongation at break of pure PU). These findings demonstrate that ArDAs could serve as a new kind of halogen/phosphorus-free flame retardant for PU elastomers. [Display omitted] • Novel halogen/phosphorus-free flame retardants were designed for PU elastomers. • The flame retardant mechanism is end group capturing by aromatic dianhydrides (ArDAs). • PHRR, THR, TSR and TCO were simultaneously reduced, and char residue was improved. • Both excellent flame retardant property and high mechanical property were achieved. [ABSTRACT FROM AUTHOR]

Background: Radial arterial line placement is commonly performed in various clinical settings, including the emergency department. However, learners are successful on the first attempt only half of the time. Simulation can provide learners with procedure practice opportunities outside of clinical practice to increase confidence and chances of success.Objectives: We set out to build an arterial line trainer that would be inexpensive and reusable, wearable, anatomically realistic, and echogenic to allow for ultrasound use. We also hoped to devise a clear option that would allow for demonstration of procedure pitfalls.Discussion: The arterial line trainer requires 4 hours of assembly time and costs $160. This includes enough material to make 48 tissue pads. The ballistics gel pad is echogenic; it can be customized with clear gel for direct anatomic visualization or dyed gel for more realism. The trainer also has a pulsatile artery for practice using anatomic landmarks. Visualization of the following important arterial line placement pitfalls is possible: suboptimal angle of approach, inadequate advancement of the catheter, and through-and-through vessel puncture.Conclusions: Our inexpensive trainer can help physicians and physicians in training conceptualize, practice, and troubleshoot the pitfalls of arterial line placement. Training programs looking to help learners understand the mechanics of arterial line placement may find it a useful tool. [ABSTRACT FROM AUTHOR]

We numerically investigate the spreading dynamics of wave packets in a one-dimensional lattice with quasiperiodic disorders and nonlinear interactions. Under moderate disorder strength, we reveal an intriguing super-ballistic diffusion driven by increasing the interaction strength from the ballistic diffusion in the non- and weakly interacting cases. We obtain a wide parameter region for such a faster-than-ballistic spreading of wave packets in the quasiperiodic lattice, although the nonlinear self-trapping is dominated under strong interactions. The super-ballistic diffusion is further analyzed based on the point source model. We also show the interaction-induced sub-diffusive spreading in the Anderson localized regime. The super-ballistic and sub-diffusive dynamics are exhibited in the spreading that starts from both the single-site and Gaussian wave packets. Our results showcase the interaction-enabled super-ballistic diffusion, which is scarce and experimentally realizable in artificial atomic or photonic lattices. • The super-ballistic diffusion induced by nonlinear interactions in a one-dimensional quasiperiodic lattice is revealed, which indicates the faster-than-ballistic spreading of wave packets. • A point source model is implemented to analyze the dynamic exponent and the physical picture of the super-ballistic diffusion. • The super-ballistic diffusion can be exhibited for single-site and Gaussian wave packets, which could be experimentally observed in artificial atomic or photonic lattices. [ABSTRACT FROM AUTHOR]

• Created the first ballistic dataset for enhanced cross-laminated timber (ECLT). • Compared partial and full penetration results utilizing eight known ballistic resistant materials. • Developed benefit-cost assessment of panel configurations. Cross-laminated timber (CLT), an engineered wood product, has grown in popularity in the United States over the last decade due to its ease of assembly, aesthetic appeal, and potential to serve as a sustainable and renewable alternative building material. The improved robustness of CLT over light-frame timber structures has increased its potential in force-protected infrastructure that must resist blast waves and ballistic projectile penetration, but softwood CLT is typically not sufficient to fulfill standard criteria for ballistic threats. To address these threats, enhanced CLT (ECLT) composite panels were manufactured with layers of various reinforcing materials (e.g., steel, FRP) placed between wood laminations. These panels were tested against various ballistic threats during two sets of laboratory tests in order to provide a basis for future research. The first set of testing subjected laboratory-produced Southern Yellow Pine (SYP) ECLT to 84 shots of 0.50-inch (1.27 cm) steel sphere projectiles to evaluate the performance of various reinforcing materials, layups, and fastening methods. A subsequent set of tests subjected commercially produced ECLT of steel-reinforced Spruce-Pine-Fir (South) (SPF-S) to 36 shots of NATO ammunition projectiles traveling at realistic, standard striking velocities. Except for a panel using four layers of a thin and finely woven steel hardware cloth, steel reinforcement was effective in stopping projectiles from all three types of NATO ammunition fired. Ultimately considering the results of these two sets of tests, an initial cost-benefit structure was developed and discussed to compare ECLT configurations holistically, a multi-material wood analytical model framework was established and compared to experimental results, and the first ballistic experimental database for ECLT was created. [ABSTRACT FROM AUTHOR]

This research continues the research of Deng et al. (2022) [1], using Discrete Element Method (DEM) coupled with Finite Element Analysis to solve shotgun exterior ballistics. The simulation examples in this research are using an Italian-made 24 gm #9½ birdshot with 433 pellets fired from 30" long, 12-gauge cylinder and full choke barrels. The simulations of shotgun exterior ballistics of this research included pellet swarm velocity and the pellet dispersion at different distances until 50 yards away from the muzzle. The ballistics simulation of the pellet swarm is completed from interior to exterior consecutively after the shotshell is fired inside the chamber so all ballistics performances can be calculated at one time. Three forces were applied to the pellets for exterior ballistics simulation: the contact force between pellets, the aerodynamic separation force between pellets, and the drag force. Because of the complexity of the aerodynamic forces exerted on pellets, this research used an equivalent aerodynamic force to simulate this complex phenomenon. Two birdshot models with different pellet formations were created; the first one was simulated to calibrate the separation scale factor defined in aerodynamic separation force, and the second one was used for validation and sensitivity of the model. The simulation results show that for #9½ birdshots fired by cylinder barrel, the average Effective Shot Dispersion (ESD) of pellet dispersion of both birdshots inside the 30" diameter of the target circle at 40 yards from the muzzle is 398.53, which is remarkably close to 396.98 of the experiment result. The simulation of the average pellets' target hit rate is 77.14% (inside the 30" diameter of the target circle), which is also remarkably close to the experiment hit rate of 77.57%. The same birdshot fired from a full choke barrel shows that ESD and hit rate rose to 406.34 and 83.14%, respectively. These results demonstrate the effectiveness of using the discrete element method in conjunction with the proposed equivalent aerodynamic force to predict the shotgun's interior and exterior ballistics. [Display omitted] • The equivalent aerodynamic forces were formulated from experiments of two pellets flying near to each other. • An Italian made 12-gauge 24 gm. #9½ birdshot with 433 pellets fired from 30-in long cylinder and full choke barrels were simulated. • Two birdshot models with different pellet formations were created to validate the sensitivity of the model. • Average simulated pellet dispersion at 40 yards fired by cylinder has only 0.43% error compared to the experiment. • Birdshot fired by full-choke barrel has 6.0% higher target hit rate compared to cylinder barrel did. [ABSTRACT FROM AUTHOR]

The first goal of this work is to find a regression law for PVC (Polyvinyl Chloride) coupled to hydrogen peroxide on a 10-N-scale hybrid thruster, which appears to be suitable for small satellites when, for example, manoeuvres are required for orbital control purposes. Different techniques were initially analysed in order to reconstruct the ballistics inside the combustion chamber, starting from the experimental data. Subsequently, even if the different techniques lead to similar results, the one that takes into consideration the greatest number of the experimental measurements was chosen for the post-processing, and three different regression curves were obtained according to various criteria. The resulting regression laws coming from the selected method appear to be in agreement with the experimental results and constitute a powerful means for designing engines with this fuel. Finally, a performance analysis has been performed and in-space thrust and specific impulse have been estimated. PVC shows excellent performance and can be a good candidate for this type of applications, on a par with other more popular polymeric materials. [ABSTRACT FROM AUTHOR]

The ongoing pursuit of space and hypersonic flight continues to expose critical gaps in the understanding of material behavior under hypervelocity impact (HVI) and hypersonic flow conditions. Such limitations pose serious risks for aerospace vehicles, spacecraft, hardened structures, defensive systems, etc. Consequently, the development of materials and systems that can endure HVIs and hypersonic flight is a major obstacle in the quest for sustainable space exploration, reusable air-breathing hypersonic vehicles, and enduring protective structures. HVIs (≥ 3.0 km/s) can induce severe material deformation, erosion, fracturing, fragmentation, melting, vaporization, and sublimation. At the same time, hypersonic (≥ Mach 5) vehicles may be subjected to intense thermal and mechanical loads. Addressing these grand challenges requires a multifaceted and interdisciplinary approach, combining well-designed experiments with physics-based analytical and numerical modeling. Studying material behavior under HVIs and hypersonic conditions has been facilitated by two-stage light gas gun (2SLGG) aeroballistic ranges for almost seven decades. This current study surveys over 90 2SLGG aeroballistic ranges operational since 1990 to assess global launch and experimental capabilities. The 2SLGG's origins and research applications are explored, highlighting its significance in various fields, including shock physics, planetary science/defense, military defense, nuclear physics, hypersonic vehicle survivability and performance, and spacecraft micro-meteoroid/orbital debris protection. A summary of relevant HVI phenomena is presented to underscore the importance of 2SLGGs and to elucidate similarities and differences among various 2SLGG aeroballistic ranges and their supporting methods/tools. The 2SLGG's working principles are explained, and configurations and operations are compared. Modifications resulting in "three-stage light gas guns" are briefly mentioned for completeness. The full range of current 2SLGG performance capabilities is assessed with impact kinetic energies ranging from ∼ 10 joules to nearly 100 megajoules, and the facility survey results are used to explain the variations in aeroballistic range tankage, experiment types, research applications, and diagnostic systems. Finally, an overview of 2SLGG performance prediction methods is provided, featuring notable empirical, analytical, and numerical approaches. • Survey of over 90 2SLGG aeroballistic ranges active since 1990 worldwide. • 2SLGG's impact in multiple fields like military and space highlighted. • Detailed 2SLGG working principles and three-stage gun modifications explained. • 2SLGG performance spectrum from 10 J to 100 MJ detailed. • Variability in 2SLGG ranges and their scientific uses described. [ABSTRACT FROM AUTHOR]

Boron carbide, with a nominal stoichiometry of B 4 C, is a highly desired ceramic candidate for armor applications due to its high hardness derived from the complex crystal structure. However, stress-induced local amorphization can lead to failure and is a known challenge for this material which must be addressed for applications in ballistic environments. Understanding boron carbide's atomic structural behavior and bonding environment is critical in determining effective strategies to mitigate these issues. In this work, the thermo-structural behavior of B 4 C has been studied in detail using a conical nozzle levitator system coupled with in-situ synchrotron X-ray diffraction. Lattice expansion and the resulting thermal expansion coefficients (CTEs) were determined from 25-2100 °C. Rietveld refinements showed anisotropic atomic displacement for each of the 4 unique sites as a function of temperature. An exceptionally large z-axis displacement for the boron chain center is linked to bond weakness and may be linked to fa α 11 ster expansion of the α 33 relative to CTEs. Thermally induced lattice changes can inform the use of boron carbide at elevated temperatures as well as help develop strategies for mitigating structural failure for armor applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Ceramic Matrix Composites (CMCs) have many interesting properties, mainly light weight, cost efficiency, low density, high compressive strength, high hardness and durability. Hence, they emerged as a boon to the development of personnel armors in the past. The current work aims to review various new methodologies adapted for the reinforcement of Alumina (Al 2 O 3) CMCs in recent times, including some of the interesting results obtained with respect to mechanical properties, suitability of the synthesized composites for armor applications, and the upcoming reinforcement trends. Finally, studies related to reinforcement in Al 2 O 3 CMCs, specifically towards armor applications have been consolidated to arrive at some of the important inferences for concluding reasonably. [ABSTRACT FROM AUTHOR]

• Thermal modification does not significantly change the ballistic performance of coastal western hemlock CLT. • Density and hardness do no fully encompass the energy absorbing capacity of CLT under small arms ballistic threats. • Empirically fit UFC partial penetration equation formulations fit treatment specific datasets with minimal error. • One global UFC partial penetration equation can be utilized for design with an appropriate safety factor. To test and understand the potential for integration of thermally modified coastal western hemlock CLT systems in military applications, 109 ballistic experiments were conducted at the United States Army Engineer Research Development Center's Fragmentation Simulation Facility. For a range of CLT thicknesses, the depth of penetration and residual velocities were recorded for different striking velocities utilizing a 0.50 caliber steel sphere projectile. This information was used to compare and add to the existing ballistics data for CLT, investigate the effects of thermal modification on high strain rate loading of wood, assess physics-based empirical design equations used by the Unified Facilities Criteria, and evaluate energy absorbing behavior at a range of thicknesses and striking velocities. The experimental results showed that thermal modification does not significantly alter the full and partial penetration performance of coastal western hemlock CLT. However, the mechanism of fracture along the path of the projectile differed, which indicates that the model parameters used in the UFC design equation (density, hardness, and projectile properties) may not fully encompass the ballistic failure mechanisms of CLT. [ABSTRACT FROM AUTHOR]

A tribological model is presented that provides a correlation between bullet velocity and friction force in firearms. The model is based on the observation that higher velocities result in lower friction and assumes that the surfaces of the bullet and barrel consist of elastic asperities. The model predicts that as the relative velocity increases, the asperities are less likely to return to their neutral positions. The model was tested using experimental muzzle velocity and gas pressure measurements for caliber 5.56 × 45 bullets and the results were in good agreement with the model predictions. The coefficient of friction obtained with the model is also in line with literature values for very low sliding velocities. [Display omitted] • Quantification of the velocity dependence of barrel friction. • The model is based on a transversal oscillation of asperities in the surfaces. • Verification of the model with experimental data in 5.56 × 45. [ABSTRACT FROM AUTHOR]

The Material Point Method (MPM) has appealing attributes for simulations involving large deformation of materials with history-dependent constitutive laws. It avoids the mesh tangling errors of Lagrangian finite element methods, as well as the advection errors typical of Eulerian or ALE methods. Recent developments in the MPM have led to a better understanding of the error and dissipation that arise in the particle-to-grid and grid-to-particle mapping, but significant error and high-frequency noise can still occur in simulations involving strong shock waves. This error appears to be associated with the kinematics on the background computational grid common to all MPM implementations. An investigation of forward- and reverse-ballistic impact simulations has revealed that sub grid-scale variations in the material state arise as the shock front enters a grid cell, and that this non-equilibrium state can persist unless the background grid has some means to relax the resultant particle-scale noise. Relaxation can occur when (i) the background grid shape functions have non-constant gradient, (ii) the shocked material has a sufficiently high velocity relative to the background grid, or (iii) the velocity field is enriched with additional degrees of freedom for treating weak discontinuities between particles. [ABSTRACT FROM AUTHOR]

In this paper, we study the interior ballistic characteristics of rockets or missiles with acceleration less than 10 g during the compressed air ejection process. First, we designed and fabricated a full-size compressed air ejection system, and utilizing different missile mass and initial pressure variables. Then, we established the mathematical model of the interior ballistics of the ejection system using the fourth-order Runge-Kutta scheme to estimate the ejection performance and results of the system. In addition, we independently built a full-scale compressed air ejection system test platform and conducted multi-condition live ejection tests. The results show that the effective travel distance of the missile is greater than 2.5 m and the acceleration is basically less than 10 g. With a certain missile mass, the acceleration peak, velocity peak and displacement of the missile are positively correlated with the initial pressure, and the opposite variable is negatively correlated. The maximum acceleration and velocity values are 10.11 g and 13.5 m/s, respectively, and the minimum values are about 3.5 g and 4 m/s. The variables are the same, the pressure peak at each measuring point in the ejection barrel is bottom > middle > upper, and the amplitude of the pressure drop between middle and bottom gradually decreases. Depending on the appearance time of the pressure point, the maximum pressure attenuation time in the ejection barrel is determined to be 0.838 s, and the minimum is 0.343 s. Comparing the pressure peak points at the bottom, middle and upper with the calculated pressure curve, the attenuation trend of the two is basically the same. Therefore, the research results show that the full-scale compressed air ejection system is effective and practical, and the test results provide data reference for related launches. [ABSTRACT FROM AUTHOR]

A vast majority of widely accepted granular segregation mechanisms are attributed to dynamic phenomena such as percolation, kinetic sieving, convection-induced segregation, condensation, inertia and granular temperature gradients. We distinguish the ballistics of the particles from such dynamic and material properties and show that the former is a dominant mechanism in the segregation of particles sedimented in a container. We first perform granular sedimentation experiments with glass beads in water that exhibit size-segregation of bidisperse grains. We then show through simulations using a simple, first-order model that the ballistics of the particles alone is sufficient to qualitatively predict this segregation. Segregation of a bidisperse sample poured through different geometries. The segregation observed in experiments is reproduced in a simulation that considers only ballistics of the particles. Thus, isolating geometric effects shows that the confinement, pouring source and the topology of filled particle contribute to the dominant segregation mechanism. Unlabelled Image • Geometric cuases of granular segregation in water is studied in isolation. • A ballistic event driven simulation predicts the outcome of segregation experiment. • The confinement and the pouring source geometry influences segregation. • Material and dynamic properties and angle of repose are less relevant for this segregation mechanism. [ABSTRACT FROM AUTHOR]

Gun-related eye injuries are relatively common in the context of gunshot wounds to the head and neck. Many of the fundamental principles of gunshot wound management apply to the care of these patients, but the complex anatomy and functional relationships of the periocular region do pose special challenges. We provide a focused primer for physicians seeking a more in-depth understanding of gun-related eye injuries and present 3 representative cases outlining the spectrum of pathology, provide a focused review of the relevant ballistics concepts, and discuss the management of injuries to the periocular soft tissues, orbital structures, and globe. We found that good cosmetic and functional results can often be achieved with appropriate early intervention, but visual prognosis may remain guarded despite optimal treatment. [ABSTRACT FROM AUTHOR]

This paper presents a method for obtaining time dependent back face deformation (BFD) data for body armor during ballistic impact using a clear ballistics gelatin backing and high-speed cameras to capture the deformation profile. Using this method, baseline fabric characterization data was obtained for samples comprised of varying layers of 467 g/m2 Kevlar K29 fabric impacted with 8.24 g steel ball projectile and backed with NATO standard 20% clear ballistics gelatin. For these tests, deformation depths were seen to increase with increasing impact energy and decreasing total areal density. A limited study of the various test parameters was performed by testing one additional fabric, projectile, and ballistics gelatin. From these comparisons, it was observed that 122 g/m2 Kevlar KM2+ fabric performs better per weight than 467 g/m2 Kevlar K29 fabric in terms of BFD, 9 mm FMJ projectiles produce deeper BFDs than 12.7 mm steel ball projectiles, and backing a sample with FBI standard 10% ballistics gel increases the BFD considerably over NATO standard 20% ballistics gel. [ABSTRACT FROM AUTHOR]

Ballistics (the linkage of bullets and cartridge cases to weapons) is a common type of evidence encountered in criminal cases around the world. The interest lies in determining whether two bullets were fired using the same firearm. This paper proposes an automated method to classify bullets from surface topography and Land Engraved Area (LEA) images of the fired pellets using machine and deep learning methods. The curvature of the surface topography was removed using loess fit and features were extracted using Empirical Mode Decomposition (EMD) followed by various entropy measures. The informative features were identified using minimum Redundancy Maximum Relevance (mRMR), finally the classification was performed using Support Vector Machines (SVM), Decision Tree (DT) and Random Forest (RF) classifiers. The results revealed a good predictive performance. In addition, the deep learning model DenseNet121 was used to classify the LEA images. DenseNet121 provided a higher predictive performance than SVM, DT and RF classifiers. Moreover, the Grad-CAM technique was used to visualise the discriminative regions in the LEA images. These results suggest that the proposed deep learning method can be used to expedite the linkage of projectiles to firearms and assist in ballistic examinations. In this work, the bullets that were compared were air pellets fired from both air rifles and a high velocity air pistol. Air guns were used to collect the data because they were more accessible than other firearms and could be used as a proxy, delivering comparable LEAs. The methods developed here can be used as a proof-of-concept and are easily expandable to bullet and cartridge case identification from any weapon. • The classification of bullets based on LEA topography using machine learning. • Features were extracted using Empirical Mode Decomposition and entropy measures. • Bullet classification was performed using the whole image of LEA and deep learning. • DenseNet121 provided high classification performance. [ABSTRACT FROM AUTHOR]

• Two field tests on concrete targets subjected to a projectile penetration followed by charge explosion were conducted. • The failure mode and stress waves in concrete were experimentally obtained. • Two-step numerical models based on the Kong-Fang concrete material model and SPG method were developed and validated. • The influences of projectile penetration on destructive effects caused by following charge explosion were clarified. The earth penetration weapons (EPWs) usually penetrate into protective structures firstly, and then detonate the charge to induce high-intensity blast stress waves to cause further damage. Existing investigations on the destructive effect caused by the following charge explosion after penetration of EPWs are very limited. To clarify the combined destructive effect in concrete material caused by an EPW, an experimental and numerical investigation on failure mode and stress wave propagation in concrete target subjected to a projectile penetration followed by charge explosion was conducted in the present study. Firstly, two field tests on high strength fiber-reinforced concrete targets subjected to a projectile penetration followed by charge explosion were conducted, in which the failure and blast waves in concrete targets were comprehensively obtained. Then two-step numerical models based on the Kong-Fang concrete material model and SPG method were developed and validated against the experimental data. Finally, based on the validated numerical models, the influences of projectile penetration on the destructive effect caused by following charge explosion were analyzed. The numerical results demonstrated that the damage caused by projectile penetration has significant influences on the final failure mode and stress wave propagation in concrete targets. The research results can provide an important reference for the design of protective structure against EPWs. [ABSTRACT FROM AUTHOR]

Computational fluid dynamics is becoming a key tool for reducing the hybrid rocket operation uncertainties and development cost, but numerous challenges, due to the complexity of modeling the solid fuel consumption mechanism and the interaction with the reacting flowfield, have still to be addressed. These latter features are further complicated with paraffins for the melted-fuel entrainment phenomenon. This paper presents a computational thermo-fluid-dynamic model of the internal ballistics of hybrid rockets burning gaseous oxygen and paraffin-based fuel. With the purpose of predicting the local fuel regression rate, the model is coupled with an improved gas/fuel-surface interface treatment based on local mass, energy and mean mixture fraction balances, combined to an additional analytical equation for the calculation of the entrainment fraction of the fuel consumption rate. Parametric analyses are carried out to assess the effect of fuel properties on the regression rate. Several experimental test cases, obtained from static firing of a laboratory-scale rocket, are simulated. Calculated regression rates show an error with respect to the measured data around 10% in the worst case. Chamber pressure is predicted with lower accuracy, with errors less than 20%; the main factor of deviation is shown to be the estimation of the combustion efficiency. [ABSTRACT FROM AUTHOR]

The detection and interpretation of gunshot residue (GSR) can play an important role in the investigation of firearm related incidents. Recently, the potential of organic compounds to provide an additional means to discriminate between GSR and environmental particles, in particular in cases where lead-free ammunition is used, has been highlighted. This work describes a method for the extraction and detection of complementary organic and inorganic compounds from a single GSR sample, using a methodology that makes implementation in the current standard procedure feasible. GSR samples were collected from the shooter's hands following double and single discharges, using the traditional adhesive carbon aluminium stubs. Analysis of organic compounds was performed using solid-phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), followed by analysis of the traditional inorganic particles using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Detection of both categorised organic GSR compounds (e.g. ethyl centralite, diphenylamine and 2-nitrodiphenylamine) and characteristic inorganic GSR has been achieved. Given the fact that the detected organic GSR compounds are relevant with respect to the confirmation of GSR materials, this method has successfully demonstrated the ability to obtain a total chemical profile from a single GSR sample, which has the potential to increase the probative value of GSR evidence. [ABSTRACT FROM AUTHOR]

Highlights • Ballistic impact tests on 4 mm thick Weldox 700 E steel plates struck by blunt rigid projectiles were conducted and a failure mode of shear plugging was identified in the tests. • The strength and fracture models of the steel were calibrated using a hybrid experimental-numerical method. • FE simulations were carried out by using either a modified version of the Johnson-Cook (MJC) fracture criterion or the Lode dependent Modified Mohr–Coulomb (MMC) fracture criterion. • FE simulations using the MJC and MMC fracture criteria predicted almost the same ballistic performance of the targets. • For targets of Lode dependent fracture, FE simulations showed that the Lode dependent fracture criterion would predict a much lower ballistic limit for less ductile targets. However, for targets with high ductility, introducing the Lode angle into the fracture criterion would not obviously alter the ballistic limit prediction. Abstract The necessity of incorporating the Lode angle into a fracture criterion in predicting ballistic resistance of ductile metal plates has not been well elucidated so far although the ductility of a metal may be Lode dependent. In this paper, 4.0 mm thick Weldox 700 E steel plates were fired by 5.95 mm diameter blunt rigid projectiles in a one-stage gas gun in the impact velocity range of 141.2 m/s∼275.7 m/s. A failure mode of shear plugging was observed in the test and the ballistic limit was obtained by fitting the initial-residual velocity data. An axisymmetric finite element (FE) model corresponding to the test was built in ABAQUS and then was utilized to predict the ballistic resistance and fracture behavior of the targets. In the FE model, a slightly modified Johnson-Cook constitutive relation was companied by either a Lode independent modified Johnson-Cook (MJC) or the Lode dependent modified Mohr–Coulomb (MMC) fracture criterion. The plasticity and fracture of the metal were fully calibrated by a series of mechanical tests under varying stress states, strain rates and temperatures. According to the tests and parallel FE simulations, it was found that the fracture of Weldox 700 E is obviously Lode dependent. However, ballistic simulations using the MMC and MJC fracture criterion predicted very close ballistic limit velocity and similar shear plugging failure mode when compared with the test results. The dominant stress state of the material failed in the process of shear plugging was revealed by detailed FE analysis and it was found that the ductility of the metal is quite different on the dominant stress state according to the two fracture criteria. To interpret the current simulation results, further FE simulations were carried out on fictitious metals and it was found that for less ductile metallic plates the MMC fracture criterion predicts a much lower ballistic limit velocity (as much as 22%) when compared with the simulation result from the MJC fracture criterion. In contrast, for metal plates with high ductility, the simulations from the two different fracture criteria would produce quite close ballistic limit velocity predictions. [ABSTRACT FROM AUTHOR]

Highlights • Created first-ever public ballistic data set for Cross-laminated Timber. • Related the ballistic performance to the species of wood found in the CLT (Spruce Pine Fir – South and Southern Yellow Pine). • Developed and calibrated models for predicting the embedment depth as well as residual velocity. Abstract Cross-laminated Timber (CLT) is a relatively new building material that has gained recent attention in the United States construction industry. CLT is a prefabricated, engineered wood product, composed of three or more plies of lumber with alternating ply directions. CLT is relatively strong and stiff, with the potential to meet the requirements for structures that are subjected to a variety of loading conditions. While CLT's response to static, dynamic (i.e., seismic), and fire loads has been characterized in the past, its response to the loads seen in force protection scenarios (i.e., blast or ballistic) is much less understood. In order to begin to fill this gap in knowledge, one of the first known sets of ballistic experiments were conducted on CLT and the results were used to develop and validate predictive models. This article describes the results of 122 ballistic experiments conducted at the United States Army Engineer Research and Development Center (ERDC). The experiments were conducted on two species of CLT of varying thicknesses: Spruce Pine Fir-South and Southern Yellow Pine. The experiments measured either penetration depth or residual velocity over a range of intermediate striking velocities. The effects of weathering (i.e., moisture content) were also explored on a data set. The results of the experiments were compared to existing United States Unified Facilities Criteria models for predicting the ballistic response of wood. The findings show the deficiencies in utilizing this wood model for CLT and explore alternate models for prediction. In general, it was found that models that incorporate both projectile and CLT target parameters most accurately predict the response. Most importantly, the results reinforce the necessity for re-calibration of models as new parameters are added to the CLT ballistic characterization database. [ABSTRACT FROM AUTHOR]

There has recently been an increase in the research and implementation of advanced measurement techniques to ballistic toolmark identification. This has led to a shift from greyscale imaging to the acquisition of dense areal datasets. With the addition of mathematical correlation algorithms, these advanced techniques will be advantageous in criminal investigation. However, with the use of areal topography comes the addition of height point data which may differ in primer caps of varying material composition. This study discusses the differences in the overall topography of firing pin impressions in different primer cap materials, and the effect it has on the successful correlation of ballistic toolmark evidence. [ABSTRACT FROM AUTHOR]

The insufficient recognition of injuries by the BB-gun (regarded as toys for children) has led to its increasing misuse without permission, which has caused many public safety issues. Aiming to enhance the understanding of the injuries by the BB-gun, the experimental and numerical study of BB-Gun pellet penetrating "cowhide + gelatine" composite target was comprehensively carried out. It was confirmed from the experiment that BB-Gun is capable of inflicting severe or fatal wounds to important organs, and perforating the skin or not could be employed to evaluate the safety of BB-guns. Moreover, three forms of ballistic limit (including: velocity, kinetic energy and specific kinetic energy) of typical BB were calculated and analyzed by reasonably validated numerical simulation method. Additionally, a formulation was acquired by dimensional analysis based on the simulation results and was verified to accurately predict the ballistic limit velocity of BB with different mechanical properties. The method may help to improve the understanding on the minimal velocity needed to perforate skin and may be advised as the determination of the safety of BB-gun. [ABSTRACT FROM AUTHOR]

Highlights • Ballistic resistance evaluated for fabric-metal assemblies, as well as their metal and fabric components. • Significant effect of fabric-metal sequence on ballistic resistance of fabric-metal assemblies, which varies with number of fabric plies in the assembly. • Analysis of interaction between fabric plies and metal plate for various fabric-metal sequences. • Explanation of the influence of fabric-metal sequence on ballistic resistance based on the interaction between fabric plies and metal plate. Abstract Fabrics woven from high-strength fibres are increasingly employed for protection against projectile impact, because of superior mechanical properties. In some applications, high-strength fabrics are combined with metallic components to provide sufficient structural rigidity and strength – e.g. for vehicle bodies, turbine engine fragment barriers, building doors, etc. An understanding of how the fabric-metal layer sequence affects the resulting ballistic resistance, is essential for effective design of such fabric-metal assemblies. This motivates the current study, whereby multiple plies (1, 2 or 4) of Twaron (T) aramid fabric were combined with an aluminium alloy (A) thin plate to form a lightweight protective panel. The projectile impact penetration resistance of three types of fabric-metal arrangements were examined – i) the aluminium alloy plate as the impact face; ii) the Twaron fabric as the impacted layer; iii) the aluminium alloy plate sandwiched between fabric layers. For assemblies with a smaller number of fabric plies (i.e. 1 or 2), siting the aluminium alloy plate as the rearmost layer results in a significantly higher impact energy absorption capacity, compared to having the aluminium alloy plate as the impact face – e.g. for (A+1T) assemblies, i.e. Al plate+1 ply of Twaron, 1T/A (impact face layer appears first in this nomenclature) performs much better than A/1T. For (A+2T) assemblies, 2T/A provides the highest impact resistance, A/2T is the weakest, and 1T/A/1T lies in between. However, when the number of fabric plies is increased to 4, a variety of responses was observed. An A/4T configuration absorbs significantly higher energy than a 4T/A arrangement, while a symmetrical 2T/A/2T sequence absorbs less energy than either an A/4T or 4T/A configuration. High-speed optical photography images and post-test specimens were analysed, to examine the deformation and failure modes of the fabric plies and Al plate in the fabric-metal targets, and how they are affected by the fabric-metal sequence. These help identify the interaction between the fabric plies and Al plate for various fabric-metal sequences, in order to account for the phenomena observed in experiments. [ABSTRACT FROM AUTHOR]

Abstract The ballistic reliability of composite armors is significantly affected by the random material properties. In this paper, the mosaic SiC ceramics/ultra high molecular weight polyethylene (UHMWPE) composite targets with bonding adhesives are tested near the limit ballistic penetration conditions. The uncertain material and adhesive properties led to complete penetration and partial penetration at bullet initial velocity of 776 m/s and 791 m/s, respectively, and a contrary tendency is also observed in the tests between the bulging deformation and the minimum target thickness of back plate. A state function of penetration for reliability evaluation is formulated based on a validated numerical model. Results from sensitivity analysis indicate that twelve uncertain material parameters are strongly sensitive to the penetration state. Then, the ballistic reliability under the test velocities is obtained by both Monte Carlo method and design point method. Finally, an optimization problem with a probability constraint is established in order to achieve a minimum deformation. The results show that the bulging deformation and the value of penetration state function vary with the adhesive strengths oppositely. Therefore, the adhesive strengths are designed to control the contradiction between the deformation and the minimum target thickness. It is significant to recognize the uncertain properties of composite armors and to improve the ballistic performance against armor-piercing bullet. [ABSTRACT FROM AUTHOR]

Azufral is one of the most touristic, but also one of the most explosive active volcanoes of SW-Colombia. Although no historical eruptions have occurred, the potential thread is inferred from the predominance of dacitic pyroclastic units and lava domes since the Holocene. This paper presents new stratigraphical and compositional data of the uppermost and thickest proximal pyroclastic deposits exposed on the current inner and outer SE crater rim. The studied eruption units correspond to parallel and low-angle cross-bedded vitric-crystalline to lithic-crystalline tuffs. The absence of interbedded paleosols or epiclastic deposits indicates continuous eruptive activity throughout the studied succession. Criteria for stratigraphic package division at proximal sites includes erosive contacts, marked changes in grain sizes, and ballistic-bearing horizons. Each package comprises several bedsets consisting of two to three beds of distinctive lithofacies associations suggesting deposition from diluted pyroclastic density currents. Temporary partial or total conduit obstruction conditions could also be inferred from the presence of ballistic horizons. Petrographical and geochemical analyses from a type-bedset with fresh, poorly to moderately vesicular rhyolitic glassy particles and the mineral association Pl + Amp + Bt + Fe-Ti oxides ± Qz microcrysts suggest the presence of juvenile material. Textures and mineralogy of glassy ash particles are the same as those in large ballistic blocks, which are dacitic in whole-rock composition. Geochemical analyses suggest that magma evolution was mainly controlled by Pl + Amp + Bt + Py + Fe-Ti oxides fractionation and magma recharge events. All Pl and Amp microcrysts in the studied juvenile ash and ballistics can be grouped into two populations: (i) unzoned microcrysts and (ii) zoned microcrysts. Zoned microcrysts have evolved and partially corroded cores, coated by a more Mg-rich (Amp) or An-rich (Pl) mantle, and followed by an outermost Fe-rich (Amp) or Ab-rich (Pl) rim that broadly overlaps with the composition of the unzoned microcrysts. Textures, mineral composition, and pre-eruptive conditions obtained from similar-sized Amp, Pl and Fe-Ti oxide microcrysts within the juvenile ash and a juvenile ballistic provide evidence of complex crystallization paths before final decompression and eruption. • Dacitic vulcanian explosions lead to hazardous proximal surges. • Comparing fresh glassy ash and ballistics helps to discern the juvenile or accessory provenance of pyroclasts. • Crystal populations unravel hints on the subvolcanic context. • Co-existing microcrysts had at least two different crystallization paths. • Magma recharge took place before eruption. [ABSTRACT FROM AUTHOR]

Abstract To study the aeroengine containment capability at high temperatures, experimental and numerical investigations have been carried out to determine the ballistic performance and energy absorption characteristics of GH4169 alloy thin plates at temperatures ranging from 25–600 °C. First, experiments were conducted using a gas gun. Target plates were impacted by projectiles with various initial velocities. The effects of the temperature and initial velocity on the deformation, failure pattern and energy absorption of the plate were correspondingly obtained. The experimental results showed that at higher temperature, the deformation of the target plates is greater, the energy absorbed by the target plates is smaller and the ballistic limit velocities are lower. The petal deformation of the target plate caused by bending is severe at the temperature of 600°C. Second, numerical simulations of the impact were conducted by an explicit dynamics FE code (LS-DYNA). The Johnson-Cook constitutive model with parameters obtained from split Hopkinson pressure bar (SHPB) experiments was used to describe the materials properties of the plates at various temperatures and strain rates. It was found that the numerical results are consistent with those obtained by the ballistic experiments. In addition, the results of the numerical simulations also showed that the ballistic limit velocity of the target plate exhibits an approximately linear relationship with the temperature of the target plate. The energy absorbed by the target plate is decreased by 18% and 9% at 600 °C and 300 °C, respectively, compared with that at 25 °C. [ABSTRACT FROM AUTHOR]

In this paper, the effect of the chemical composition of .22LR bullets was studied and correlated to the extent and quality of the markings left after shooting them with the same gun. Scanning electron microscopy and optical comparator microscopy equipped with 3D and profilometry modules were used as non destructive techniques with two main purposes. The first is to assist the firearm examiner in the choice of the ammunition most suitable for preparing the test bullets. The second is to propose an approach, crossing data from optical microscopy, profilometry and space-resolved chemical analysis, for explaining the morphology of striae, whether continuous or interrupted. Among the most notable results is the finding that commercial .22LR ammunition show very wide interbrand, interlot and intralot variability. A selection of test ammunition solely based on the same brand and model used on the crime scene is therefore not suitable, urging the need for a more accurate choice, based on a preliminary chemical analysis. [ABSTRACT FROM AUTHOR]

Synthetic models, also called "surrogates", are commonly used in wound ballistics in order to simulate human tissues. Despite several surrogates are worldwide accepted and used; some of them have not been yet fully validated and their limits for forensic reconstructions have not been deeply investigated yet. In this work we present a homicide/suicide case involving three gunshots to the head with bullets retained in the skull or beneath the scalp. Reconstruction of these cases was performed preparing three individual synthetic head models based on post-mortem computed tomography (PMCT) measurements. Ballistic soap, polyurethane plates and 10% ballistic gelatine at 4°C were used as simulants in individually adapted thickness. Ballistic tests were performed using the questioned firearm and ammunition type. The damages on the synthetic models have been compared to the findings in PMCT and autopsy of the victims. Although the results highlighted general similarities in terms of injury characteristics, some of the experimental shots overpenetrated. Furthermore, the bullets recovered in the synthetic models did not show the same quality of deformations as the questioned bullets. This lack of bullet deformation in the synthetic models might be mainly attributed to the physical difference between real bones and polyurethane surrogate. [ABSTRACT FROM AUTHOR]

Highlights • Polymer composite armor from fiber-reinforced PBA as a strike panel is developed. • S glass/PBA panel can replace ceramic panel rendering lighter and safer hard armor. • The PBA composite armor shows ballistic impact resistance up to NIJ level III. • The ballistic limit of the composite panel based on ANSYS simulation is 930 m/s. Abstract The objective of this study is to measure impact performance of the composite based on glass and aramid fiber reinforced polybenzoxazine/polyurethane composites. Experimental panels were manufactured from E and S glass fiber reinforced polybenzoxazine backed by aramid fiber reinforced 80/20 polybenzoxazine/polyurethane and subjected to 7.62 × 51 mm at a velocity of 847 ± 9.1 m/s. Bases on test results the specimens did not have any perforation. Comparing the same number of ply, cone deformation on the last panel of S glass composite was significantly lower than that of specimen manufactured using E-glass composite. Such panels were tested for their resistance and the specimens completely resisted the penetration of projectiles for six shots. The numerical study of ballistic impact was undertaken to predict the ballistic limit velocity of the samples in which the value was measured to be 930 m/s. Results determined in this work indicated that such panels have an excellent ballistic characteristics to be used as raw material to manufacture body armor. [ABSTRACT FROM AUTHOR]

Abstract The vastly disparate length and time scales existing in new devices and materials born out of micro-/nano- devices have made thermal modeling and simulation more important and more difficult. The heat transfer process in one certain micro-device is essentially a thermal contact problem that involves various scales of space and time in each of the sub-components. In this communication, we utilize a newly developed computational framework to investigate problems of thermal contact involving size-effects that span the ballistic, ballistic-diffusive, and diffusive heat transfer processes. The preliminary work regarding this generalized computational framework has been published in Xue, Zhang, and Tamma (2018) and has been proved to readily resolve the problem of thermal contact between Fourier-type and nonFourier-type sub-domains. The fashion of solving the thermal inter-facial problems from the perspective of differential-algebraic equations is extended to a broad range of thermal contact problems in the present work, including both the temporal and spatial non-locality. The numerical results demonstrate the prediction of thermal response of the bodies in contact at different scales. The proposed computational framework paves the way for investigating the thermal inter-facial problems in micro-/nano- devices. [ABSTRACT FROM AUTHOR]

Highlights • Cavity dynamics in gelatin was studied. • A motion model of temporary cavity is established in gelatin penetrations of rifle bullets. • The motion model is well consistent with the penetration tests. • The radial movement of cavity is characterized by the behavior of bullet and the characteristic velocity. Abstract In wound ballistics, modeling the penetration-cavitation dynamics will set the basis for evaluating the damaging efficiency of projectiles. In our previous study, a motion model to characterize the behavior of rifle bullets has been established and verified in the gelatin penetration. In order to reveal the cavity production analytically, in combination with parameters obtained from the motion model of rifle bullet, cavity dynamics in gelatin was studied and a motion model of temporary cavity in gelatin penetrations of rifle bullets was proposed and verified by comparison with experimental results in terms of maximum cavity wall radius, radial movement along the penetration trajectory and temporary cavity profiles. It can be concluded that calculated results of the cavity motion model agree well with experiment data for penetration of 7.62 mm and 5.56 mm rifle bullets. And the radial movement of cavity can be characterized by the behavior of bullet and the characteristic velocity. It is significant for the trauma assessment to develop an appropriate cavitation model in gelatin for penetrations of rifle bullet. [ABSTRACT FROM AUTHOR]

Highlights • Pressurized borosilicate glass cylinders were tested under high-velocity impact. • Efficiency of elastomeric coating on ballistic damage was investigated. • Drop tower testing was added to verify air gun results on the cylinders. • Critical coating thicknesses to prevent initiation of ballistic damage to porcelain bushings was estimated. Abstract Pressurized borosilicate glass cylinders were used to (1) simulate experimentally high-voltage transformer bushing behavior under high-velocity impact from an air gun, (2) investigate fragment dynamics to estimate the impact range of airborne fragments, and (3) evaluate the efficiency of an elastomeric coating on ballistic damage initiation and fragment confinement. Using high-speed cameras, the velocities and directions of ejected fragments from the cylinders were determined along with fragment distribution symmetry. Drop tower testing was added to independently verify the air gun results on the cylinders through a different test under similar impact energies using flat samples of the same glass. Elastomeric coatings were also applied to both the cylinders and flat samples to increase their resistance to high energy impact. It has been shown that internal pressure in the glass cylinders plays a major role in the failure modes during high-velocity impacts. This pressure affects velocities, directions, and symmetry of fragment distribution. The fragment impact range investigation turned out to be inconclusive due to highly erratic behavior of the fragments after the blast. Most importantly, it has been ascertained that fragment dynamics are drastically altered by elastomeric coatings, producing a high level of fragment confinement both in the drop tower and gun tests. By extrapolating the air gun and drop tower data out to high power rifle energy levels, unique predictions of the critical coating thicknesses to prevent the initiation of ballistic damage and to confine fragments in borosilicate glass cylinders and C-120 porcelain bushings were achieved for the first time. [ABSTRACT FROM AUTHOR]

Abstract Today, increasing energy demand and human consumption are becoming increasingly important for the safe use, storage and transport of energy resources. Energy sources have been the target of increasing terrorism and wars since the 20th century. In the future, alternative energy sources, such as hydrogen energy, are expected to take the place of fossil energy resources. This means that ballistic threats will target these resources. In this study, for the first time in the literature, the ballistic behavior of Type 1 metallic pressurized hydrogen storage tanks made of the 6061 T6 aluminum and SS304 stainless steel alloys at the different thicknesses against 7.62 mm were investigated under usage pressure. For these alloys, the minimum safe wall thickness of the hydrogen tank is mathematically calculated using finite element analysis. Highlights • The ballistic behavior of Type 1 metallic hydrogen storage tanks were analyzed. • The minimum safe wall thickness of the hydrogen tank was calculated. • For ballistic safety, the minimum thickness of Al 6061 T6 should be 42 mm. • For ballistic safety, the minimum thickness of SS 304 should be 22 mm. [ABSTRACT FROM AUTHOR]

The ability of a metallic surface layer to protect CFRP cross-ply plates against perforation is explored. Aluminium alloy plates (either AA1050A or AA6082-T6) were placed in front of a CFRP layer, and the bilayer was subjected to either quasi-static indentation or to ballistic impact by a spherical projectile, with rigid back support or an edge-clamped boundary condition. The observed perforation mechanism of the CFRP layer is neither influenced by the presence of the metallic layer nor by the choice of loading rate (i.e. quasi-static versus ballistic). In the back-supported condition, the CFRP layers fail by an indirect tension mode that consists of tensile failure of plies in the material directly beneath the indenter or projectile. Alternatively, in the edge-clamped condition, the CFRP layers fail by a shear plugging mechanism. Although the presence of metallic layers does not suppress the shear plugging of the underlying CFRP layer, the loaded area in the CFRP layer increases by the addition of the protective metallic layer, thereby increasing the perforation resistance of the CFRP layer. [ABSTRACT FROM AUTHOR]

Directional gated imaging of hidden objects in scattering media is demonstrated using an ultrafast optical Kerr gate (OKG), in which the gating and imaging beams are focused by utilizing a cylindrical lens and a convergent lens, respectively. Owing to the spatial transmission characteristics of the directional gate, a rectangular aperture stop is formed, which leads to different resolution limits for vertical and horizontal structures of an object. By implementing directional gated imaging, the directional feature can be extracted from an original image. [ABSTRACT FROM AUTHOR]

Hypervelocity impact of a projectile on a thin plate generates a debris clouds. Largest chunk (mass) of the projectile material (called primary fragment) in the cloud poses significant ballistic threat to subsequent structure. Primary fragment characteristics (mass, velocity and exit angle) are used in assessing subsequent structure damage potential. Non-dimensional empirical equations are proposed in this paper for estimation of these characteristics. A set of simulations has been carried out using smoothed particle hydrodynamics (SPH) technique of Autodyn. Two stage light gas gun test data has been compared for validation of simulation. Simulation results for spherical projectile made of stainless steel impacting mild steel plate with impact velocity of 2–4 km/s and obliquity of 0°–60° has been analysed. Constants and radicals of the proposed equations are determined by multi variable regression of the simulation data. Comparison of the simulation data with the proposed equations shows a very good fit. [ABSTRACT FROM AUTHOR]

Modeling fiber-reinforced composites and fabrics in ballistic applications can be difficult after the initiation of damage and failure. Mesoscale models can provide accurate results, but they are much more computationally intensive than standard continuum approaches. However, an accurate continuum model for these materials requires a thorough understanding of the relevant deformation and failure mechanisms. A new continuum modeling approach was developed in which the average stresses and strains within a composite containing multiple fiber orientations are related at the element, lamina, and constituent length scales using rules of mixtures. The new approach was used to simulate a variety of mechanical and ballistic test data from different composite and fabric materials. The accuracy of the results demonstrates the predictive capability of the new model to reproduce deformation and damage of composites under generalized loading conditions. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fingermark development techniques for brass cartridge cases/plates were evaluated. • The sequence CA + GB + fluorescent dye (BY40 or Ardrox) presented the best results. • The application of the entire sequence of developers is strongly recommended. • The gaseous blowback is the main firing effect on the deterioration of fingermarks. • Handling cartridges when loading a gun has a significant influence on the fingermarks. Abstract A study was undertaken wherein different fingermark developers were evaluated for the recovery of fingermarks from brass cartridge cases, besides the evaluation of factors such as firing effects and surface characterization of the cases. The latent fingermarks on α-brass plates, fired and unfired cartridge cases were deposited and aged for 1–14 days before development with different developers. In order to mimic the fired cartridge case conditions, the brass plates were heated and examined at room temperature (RT), at 63 and at 200 °C. The sequential treatment with cyanoacrylate, gun blue and fluorescent dye has been found to be the best among other developers for the recovery of latent fingermarks on brass surfaces including fired and unfired cartridge cases. Cartridge cases and other brass surfaces were also analyzed by surface characterization methods, including X-ray diffraction, scanning electronic microscopy, energy dispersive X-ray spectroscopy and metallographic examination. The tested surfaces correspond to α-phase brass Cu 0.7 Zn 0.3 composition and have shown different surface morphologies (such as grain structure) and different levels of oxidation, even for cartridge cases obtained from the same batch. Due to this, the effectiveness of a given reagent for a specific brass surface is uncertain. Therefore, the application of the entire tested sequence of developers is strongly recommended. Further, the effects of firing on fingermarks on cartridge cases were examined, and the results indicated that the blowback of hot gases through the looseness between cartridge case and chamber wall of the firearm is the main cause responsible for deterioration of fingermarks during firing. Despite the recognized damage caused to fingermarks by the firing effects, good quality fingermarks were recovered from fired cartridge cases in which full fingermarks were intentionally deposited prior to firing. This indicates that the handling of the cartridges before and during the loading of the gun may have a strong influence on the quantity and quality of fingermarks, and that the firing itself is not the main responsible factor for the absence or low quality of fingermarks, as frequently reported in fired cartridge cases studies. [ABSTRACT FROM AUTHOR]

Firearm injuries are common in the world today, in both military and civilian settings. Research into the effects different ammunition has on the human body has been conducted using tissue simulants such as Ballistics Ordnance Gelatine. Previous research has found that with low velocity projectiles, the tissue simulants only represent a selected few organs, as the human body and its organs/tissues are not homogeneous. The aim of this research was to determine which ballistic simulants best represent the abdomen and thorax, for the purposes of anatomical modelling. A mounted firearm was used to fire specially made ammunition containing a sabot and steel spherical projectile at medium (∼500m/s) and high (∼900m/s) velocities. Test specimens of 50mm cube porcine tissues (lung, liver, kidney and heart) and ballistics simulants (20% and 10% Ballistics Gelatine and Clear Gel) were shot at and the energy loss determined using Doppler radar, optical infra-red sighting screens and high speed video. This study determined that the conclusions drawn from studies in these tissue simulants may not be an accurate representation of what occurs in human tissues and that different impact velocities produce differing results. New simulants are required to better represent the energy loss of a projectile through the organs of the abdomen and thorax and the results of this study may guide this development. Further experiments will be required to determine different concentrations of gelatine and their accuracy at representing the heterogeneous nature organs of the human body. [ABSTRACT FROM AUTHOR]

The UK Home Office test method for ballistic protective police body armours considers anterior torso impacts to be the worst-case scenario and tests rear armour panels to the same standards as front panels. The aim of this paper was to examine the injuries from spinal behind armour blunt trauma (BABT) impacts. This study used a cadaveric 65 kg, female pig barrel and 9 mm Luger ammunition (9 × 19 mm, FMJ Nammo Lapur Oy) into HG1/A + KR1 soft armour panels over the spine. Injuries were inspected and sections removed for x-radiography and micro-CT assessment. All shots over the spine resulted in deep soft tissue injuries from pencilling of the armour and the shirt worn under the armour. The wounds had embedded fabric debris which would require surgery to remove resulting in increased recovery time over injuries usually seen in anterior torso BABT impacts, which are typically haematoma and fractured ribs. The shot with the deepest soft tissue wound (41 mm) also resulted in a fractured spinous process. Shots were also fired at the posterior and anterior rib area of the pig barrel, for comparison to the spine. Similar wounds were seen on the shots to the posterior rib area while shallower, smaller wounds were seen on the anterior and one anterior rib shot resulted in a single, un-displaced rib fracture. The anatomical differences between pigs and humans would most likely mean that injury to a human from these impacts would be more serious. [ABSTRACT FROM AUTHOR]

[Display omitted] This study aims to identify the ballistic mechanisms of quasi-isotropic (QI) panels made from compliant composite laminates, focusing on the propagation of various stress waves. Three hypotheses are proposed that in terms of the propagation of stress waves, incorporating ① longitudinal, ② transverse, and ③ bending waves, QI panels would perform better than the aligned (AL) counterparts, based on simplified theoretical analyses to provide a theoretical basis for the study. 2-, 3-, and 4-ply QI panels are found to absorb approximately 23 % more energy than the aligned (AL) counterparts in the ballistic tests. The finite element (FE) models are developed using hierarchical and global-local approaches, and the results are well agreed with the experimental ones. The results elucidate the influence of QI stacks on the propagation of stress waves. The ballistic mechanisms are ultimately explored and elucidated. [ABSTRACT FROM AUTHOR]

• Ballistic, a high strain-rate method, used to produce functionally graded materials. • Hardness and microstructures are studied as functional properties. • Axisymmetric & unsymmetrical variation can be achieved. • The variation can be controlled by the leading edge shape, speed, & target material. In the present effort, impact of bullets fired at high speeds on a stationary target was used as a high strain-rate plastic deformation method to generate Functionally Graded Materials (FGMs). The bullet-shaped Aluminum alloy Al5052 specimens impacted the UHMWPE target at different projectile velocities ranging from 100 m/s to 750 m/s, to study the effect of the impact speed. Moreover, few of the projectiles impacted along the longitudinal axis whereas the remaining projectiles impacted with an obliquity to investigate the effect of leading-edge shape. The metallography of the projectile specimens fired at 750 m/s shows grain refinement from 70 ± 3 μm at the rear/ un-deformed point to 10 ± 1 μm at the front/ severely deformed point which is in the impact zone. Similar but of less magnitude variations were observed at other impact speeds also. The hardness variation was 45% (70 ± 3 HV at the rear surface to 102 ± 2 HV at the front face) at 750 m/s. Moreover, least variation in hardness and grain size was observed for projectile impacted at lowest velocity tested (100 m/s). Further, functionality in hardness and grain refinement was seen in graded direction due to shape of the projectile specimens, impact velocity, and target material. Depending upon the impact angles, axisymmetric (impacted normal to the longitudinal axis) or unsymmetrical (impacted at an angle) variation of grain refinement and hardness was observed. [Display omitted] [ABSTRACT FROM AUTHOR]

The ballistic performance of monolithic targets perforated in ductile formation by rigid projectiles can be reasonably approximated by an energy balance based on the work done in expanding a hole from zero initial radius to that of the penetrating projectile. For a specific projectile, these energy balance laws can be expressed in terms of a simple scaling law which requires an empirical fit to ballistic data. However, once this fit has been performed for a specific projectile against a specific target material, predicting the performance of other materials against this projectile can be done from a simple quasi-static compression stress–strain curve, provided the target is perforated in ductile hole formation. Four variations of ductile hole formation analytical and semi-empirical models have been reformulated as scaling laws and evaluated for their ability to characterise the performance of monolithic aluminium plates impacted by 7.62 mm APM2 projectiles at normal incidence. The database used to fit and evaluate the performance of the scaling laws incorporates more than 1600 V 50 measurements against 24 different alloys and tempering/strain-hardening combinations with thicknesses ranging from 16.2 to 63.5 mm. The highest performing scaling law formulation was found to characterize the measured V 50 to within 5% of the experimental value for over 97% of the database entries. Further improvements in accuracy are likely impossible when representative stress–strain curves are used for performance characterization rather than tests of each individual plate used in the ballistic tests. The scaling law can be applied to predict the performance of targets perforated in ductile hole formation with a high level of confidence, an example of which is provided for the 12.7 mm APM2 projectile against a range of aluminium alloys. [ABSTRACT FROM AUTHOR]

Post-mortem imaging has become more frequently used in forensic procedures, notably in a ballistic context. Despite many advances in this field, the interpretation of computed tomography (CT) can be a very complex matter. Our case illustrates the difficulties of interpretation after quasi-tangential cranial ballistic impact and keyhole wounds. These wounds are difficult to visualize on CT and are among the factors complicating the precise determination of ballistics. These sources of error remind us that CT findings must be interpreted in close comparison with autopsy findings. [ABSTRACT FROM AUTHOR]

Voronoi tessellation theory is applied to model the cells and ligaments in the open aluminum foam material. The cores of the cells are first generated by packing random spheres into the specified spatial domain. Weighted Voronoi tessellation is then applied to make the cellular structure of the foam material. For the open cell foam, the ligaments are created from the edges in the multiple polyhedron geometry. Hypervelocity impact simulation is conducted with the smoothed particle hydrodynamics method in LS-dyna. The finite element reconstruction technique is applied based on the particle output for the fragmentation analysis. The modeling and simulation techniques are verified by comparing the simulation results with testing results. The failure shown in the numerical prediction is consistent to the test result. The stress wave propagation in the foam material, which is extracted from the simulation output, is very different from that in the homogeneous material. The stress wave can only propagate inside the ligaments, and is diffused by the cellular structure. The important tensile failure pattern in the homogeneous material, which is generated by the reflection of the compressive wave on the free surface, is not observed in the foam material. The diffusion of the stress wave spreads the impact effect to a large area, leading to the enhanced dissipation of the impact energy, which increases the ballistic limit of the foam panel. [ABSTRACT FROM AUTHOR]