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A computational study of a projectile (either 2024 aluminum or TiAl6V4 titanium alloy) impacting a plate (either titanium alloy or aluminum) is presented in this paper. Projectile velocity (ranging from 250 m/s to 1500 m/s) with varying impact angles are considered. The presence of ricochet (if any) is identified over the ranges of the projectile velocity and impact angle considered. For the cases where ricochet is identified, the ricochet angle and velocity are predicted as functions of the incident angle and the incident velocity. The numerical results are compared with an analytical solution of the ricochet problem. The analytical solutions are from a model developed to predict the ballistic ricochet of a projectile (projectile) penetrator. The dynamics and the deformation of an aluminum (or a titanium alloy) projectile impacting on a finite thickness titanium alloy (or aluminum) plate are simulated. The current work is interesting in that it looks in the field of ballistics of different material combinations than are traditionally studied. The present simulations based on detailed material models for the aluminum and the titanium alloy and the impact physics modelling features in the LS-DYNA code provide interesting details regarding the projectile/plate deformations and post-impact projectile shape and geometry. The present results indicate that for no cases (for specified incoming velocities and impact angles considered) can an aluminum projectile penetrate a titanium alloy plate. The ricochet ‘mode predictions ‘obtained from the present simulations agree well with the ricochet ‘mode predictions’ given in an analytical model.

Materials capable of oxidizing in a protective manner at ultrahigh (>1700 °C) temperatures are needed to push beyond this barrier defined by SiC. Although possessing attractive mechanical properties and oxidation resistance, SiC-based materials are ultimately temperature limited by the melting point of SiO2. The vast array of ultra-high and high temperature ceramic literature indicates the majority of these materials, like borides, carbides, MAX-phases, and high-entropy ceramics, fall woefully short regarding oxidation resistance. However, for specific applications, like low-orbit aeropropulsion, high ballistics coefficient atmospheric re-entry, and hypersonic cruise, there are a few promising materials. In the present review, oxidation criteria are gathered to build application specific heuristics and are then applied to a multitude of ultra-high temperature ceramics to gauge material efficacy. Discussion of oxidation kinetics, mechanisms and reaction products is offered for each material, identifying strengths, weaknesses, and the remaining gaps in our knowledge.

Forensic reconstructions and ballistic testing requires the use of consistent and repeatable simulants. Synthetic bone has been developed to be mechanically similar to human bone; however, it does not have the same viscoelastic properties. Bone acts as brittle and stiff material and fails instantly under high-energy events such as ballistic impacts. Consequently, bone simulants for use in ballistic testing should show comparable energy deposition to mammalian bones. This study aims to determine if Synbone® flat plates could be a viable proxy for Sus scrofa (domesticus) ribs in ballistic testing with 7.62 × 51 mm Full Metal Jacket ammunition. 5 mm, 6 mm and 12 mm quartered Synbone® plates were embedded into 10% ballistic gelatin and shot using 7.62 mm ammunition. The models were then analysed to compare the Synbone® to a previous Sus Scrofa (domesticus) rib study and focused on energy deposition, the number of fragments within the block, angle of deviation, onset of yaw, the temporary cavity, and the permanent wound channel. No significant difference was seen between the Sus Scrofa (domesticus) and the 5 mm Sybone®. There were significant differences observed between Sus Scrofa (domesticus) ribs and 6 mm Synbone® for the number of fragments, energy deposition and projectile tract diameter, and significant differences seen between Sus scrofa (domesticus) ribs and 12 mm Synbone® for the depth of onset of yaw, energy deposition and projectile tract diameter. This study indicates that the 5 mm Synbone® plate is a suitable proxy for Sus scrofa (domesticus) ribs for use with 7.62 × 51 mm FMJ ammunition in ballistic testing.

The efficiency of alumina and low-density polyethylene (LDPE) composites in ballistic applications was investigated. Different concentrations of alumina were studied, 70, 75, 80, 85, 90 wt.%. The ballistic tests were carried out at subsonic speed using a compressed air system and projectile 0.22. In addition, Charpy impact tests were conducted for mechanical characterization; optical microscope images were used to evaluate the projectile after the ballistic tests; fractography studies were conducted with scanning electron microscope equipped with x-ray energy dispersive spectroscopy detector; density was measured by Archimedes experiment. The results demonstrate that the proposed composites have a good performance in ballistic applications, showing themselves to be a viable alternative. The composite with 80 wt.% alumina and 20 wt.% LDPE showed the best performance.

Because of its excellent insulation capability, the usage of a silica-phenolic charring ablator as a nozzle liner is a common practice in the solid rocket motor industry. During the design of a solid rocket motor employing a silica-phenolic nozzle liner, it is desired to conduct an accurate analysis yielding in-depth thermal response and recession characteristics. As the interior ballistics and nozzle recession rate mutually interact, the best practice is to perform a coupled solution to both. Commonly used one-dimensional analysis tools with empirical approaches for estimation of convective heat transfer rate and blowing effect generally lack sought accuracy and do not model the transient shape-change phenomenon, which affects the nozzle performance. This Paper considers governing equations for charring, including pyrolysis gas injection and surface energy balance for melting ablation, along with a boundary condition governed by interior ballistics, and demonstrates a framework in which these equations are solved with governing equations for the nozzle flowfield in a coupled manner. Development and validation of a one-dimensional material response solver based on the same governing equations is also demonstrated. Also, results from a static firing test conducted with a small-scale ballistic evaluation motor employing a silica-phenolic nozzle insert are provided. Results from both investigations are compared and discussed.

A "plated bullet" has a thin layer of electroplated metal covering the lead core of the projectile. In certain situations, this thin layer of electroplated metal can fracture upon discharge of the firearm. When such fracturing occurs, vaporous lead can escape through the fracture lines of the spinning projectile, resulting in a spiral-shaped deposition of dark residue surrounding a central bullet defect. The spiral-shaped pattern is referred to as "comet-tailing," or the "vortex effect." In this report, three homicide cases with associated comet-tailing are presented. Police, death investigators, and forensic pathologists should be aware of this unique finding.

Computational impact analysis of an E-glass fiber reinforced laminated composite structure with a conical nose shaped projectile is performed including delamination analysis. In addition to intralaminar damage analysis, interlaminar damage analysis is considered due to the laminated configuration of the protective structure. Threat is made of mild steel projectile and it is modeled using Johnson-Cook material model with ductile damage criterion. Intralaminar and interlaminar damage modeling of target material is realized in the frame of Hashin damage criteria and quadratic nominal stress criterion with Benzeggagh-Kenane fracture criterion, respectively. Stress and damage distribution both in target and threat materials are obtained by mesh gradation analysis via Abaqus/Explicit v6.19. Effect of delamination analysis in computational impact modeling is evaluated by considering the computational cost regarding CPU time and wall clock time. Larger von Mises stresses obtained when excluding interlaminar debonding in the analysis. It is found that delamination analysis significantly improved the damage evaluation of composite laminates owing to impact loading with small computational effort.

Reactive material (RM) is a new type of energetic material, which is widely used in the military technology fields such as fragmentation warheads and shaped charge warheads. Violent chemical reactions take place in the impact process of reactive materials, and how to realize the macro numerical simulation of shock-induced energy release behavior of reactive materials is one of the most urgent problems to be solved for its future military applications. In this study, a numerical simulation approach and procedure is proposed, which can simulate the shock-induced energy release behavior of reactive materials on a macro scale. Firstly, program implementation of the mechanical-thermal-chemical coupled effect model for RM is realized in the second-development interface of LS-DYNA software. Then, the adaptive simulated annealing algorithm is used to fit the chemical reaction kinetic parameters of RM using the direct ballistics test data. Finally, the simulation calculation of the fragment penetrating upon steel plate is carried out to expand the applicability of the numerical simulation approach proposed in this study. The results show that the numerical simulation approach proposed in this study can reproduce the results of the direct ballistics test more accurately, which assumes practical significance for the engineering application of reactive materials in the military field in the future.

During their operation, solid rocket boosters experience axial stresses caused among other things also by fluid mechanical loads from the internal flow. The accurate prediction of the flowfield is ...

This work describes the application of original computer graphics methods to examine the effect of inclusionswithin the solid rocket motor thrust chamber. The adoptance of a dynamic three-dimensional triangular mesh with aself-intersection removal algorithm, as the core of the burning surface regression module, allows the aforementionedtargetto bereached.Manyphenomena notmeasurablein an analyticalclosed form, likedifferent-shapedvoidswithinthe grain, can be investigated. Indeed, both local heterogeneities and surface imperfections could generate unexpectedvariations in the combustion chamber pressure pattern and early thermal protections exposure. The aforementionedtechniques are developed and tested on a ballistic simulator developed using computer graphics methods to improvemesh handling. Simulation results are carried out and discussed.

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.

The main goal of the study is to analyze methods and diagnose mechanical damage to the pipeline using functional analysis, neural networks and the finite element method. In the work, mathematical formulations of the corresponding geometrical inverse problems of the theory of shells on reconstruction of defects of lateral surface are formulated according to measurement data obtained from sensors located in a given section of the shell. The statement was given and a method for solving inverse geometric problems for a shell of Tymoshenko type was developed. The authors have offered methods for solving inverse geometric problems of identifying volumetric and crack-like defects in extended underground structures and pipelines based on the analysis of responses to unsteady elastic-wave perturbations using the mathematical apparatus of wavelet signal transformation, the finite element modeling method and intelligent software system based on neural network.

The paper describes field test results of 7.62 × 51 mm M61 AP (armour piercing) ammunition fired into mild steel targets at an outdoor range. The targets varied from 10 mm to 32 mm in thickness. The tests recorded penetration depth, probability of perforation (i.e., complete penetration), muzzle and impact velocities, bullet mass, and plate yield strength and hardness. The measured penetration depth exhibited a variability of approximately ±12%. The paper then compared ballistic test results with predictive models of steel penetration depth and thickness to prevent perforation. Statistical parameters were derived for muzzle and impact velocity, bullet mass, plate thickness, plate hardness, and model error. A Monte-Carlo probabilistic analysis was then developed to estimate the probability of plate perforation of 7.62 mm M61 AP ammunition for a range of impact velocities, and for mild steels, and High Hardness Armour (HHA) plates. This perforation fragility analysis considered the random variability of impact velocity, bullet mass, plate thickness, plate hardness, and model error. Such a probabilistic analysis allows for reliability-based design, where, for example, the plate thickness with 95% reliability (i.e. only 1 in 20 shots will penetrate the wall) can be estimated knowing the probabilistic distribution of perforation. Hence, it was found that the plate thickness to ensure a low 5% probability of perforation needs to be 11–15% thicker than required to have a 50/50 chance of perforation for mild steel plates. Plates would need to be 20–30% thicker if probability of perforation is reduced to zero.

Gumeniuk Kostiantyn, Lurin Igor, Tsema Ievgen, Susak Yaroslav, Mykhaylenko Oleksandr, Nehoduiko Volodymyr, Krymchuk Serhiy, Gryshchenko Oleksandr, Lopatiuk Kostiantyn, Maksymenko Myhailo, Dubenko Dmytro, Tsema Yegor. Woundary ballistics of biological tissue’s plastic deformation on the model of ballistic plastiline using hollow point and shape-stable bullets. Journal of Education, Health and Sport. 2021;11(11):37-57. eISSN 2391-8306. DOI http://dx.doi.org/10.12775/JEHS.2021.11.11.003 https://apcz.umk.pl/JEHS/article/view/JEHS.2021.11.11.003 https://zenodo.org/record/5659668 The journal has had 5 points in Ministry of Science and Higher Education parametric evaluation. § 8. 2) and § 12. 1. 2) 22.02.2019. © The Authors 2021; This article is published with open access at Licensee Open Journal Systems of Nicolaus Copernicus University in Torun, Poland Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author (s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non commercial license Share alike. (http://creativecommons.org/licenses/by-nc-sa/4.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited. The authors declare that there is no conflict of interests regarding the publication of this paper. Received: 10.10.2021. Revised: 22.10.2021. Accepted: 09.11.2021. WOUNDARY BALLISTICS OF BIOLOGICAL TISSUE’S PLASTIC DEFORMATION ON THE MODEL OF BALLISTIC PLASTILINE USING HOLLOW POINT AND SHAPE-STABLE BULLETS Kostiantyn Gumeniuk1, Igor Lurin2, Ievgen Tsema3, Yaroslav Susak3, Oleksandr Mykhaylenko4, Volodymyr Nehoduiko5, Serhiy Krymchuk4, Oleksandr Gryshchenko4, Kostiantyn Lopatiuk4, Myhailo Maksymenko4, Dmytro Dubenko4, Yegor Tsema6 1Ukrainian Military Medical Academy of Ministry of Defense of Ukraine, Ukraine, Kyiv 2National Academy of Medical Sciences of Ukraine, Ukraine, Kyiv 3Bogomolets National Medical University, Ukraine, Kyiv 4State Research Forensic Center Ministry of Internal Affairs of Ukraine, Ukraine, Kyiv 5Military Medical Clinical Center of the Northern Region, Ukraine, Kyiv 6Faculty of Cybersecurity, Computer and Software Engineering of National Aviation University, Kyiv Correspond author: Ievgen Tsema, MD, professor, Department of Urgent and Vascular Surgery, Bogomolets National Medical University, Kyiv, Ukraine, Email: hemorrhoid@ukr.net Abstract Introduction. Modern military conflicts make many challenges for military surgeons associated with the use of new types of weapons – hollow point bullets. The solution to this problem, firstly, depends on studying the characteristics of the terminal ballistics of such ammunition and comparing the data obtained with the characteristics of traditional weapon. The aim of the work is to conduct experimental modeling of the wound canal and residual wound cavity, which is formed due to plastic deformation from hollow point and non-hollow point bullets. Materials and methods. The studies were carried out on 40 blocks of ballistic plasticine, in each of which one shot was fired from an AKS-74 assault rifle and a ZBROYAR Z-10 carbine. Depending on the type of ammunition, the blocks of ballistic plasticine were divided into 4 groups: Group 1 – 10 blocks into which shots were made with 5.45 mm non-hollow point military cartridges with "PS" bullets with a steel core "7N6"; Group 2 (10 blocks) – 5.45x39 mm cartridges with "V-Max" hollow point bullets; Group 3 (10 blocks) – with cartridges 7.62x39 mm; Group 4 (10 blocks) – cartridges 7.62x39 mm with hollow point bullets of the "SP" type. Results and discussion. Only for a 5.45 mm military cartridge with "PS" bullets, both inlet and outlet bullet holes were detected in all 10 observations. When using non-hollow point bullets, the outer area of the bullet inlet correlates with the caliber of the projectile (1.6 times larger when using 7.62 mm bullets). For hollow point bullets, the caliber of the projectile does not significantly affect the area of the inlet (P < 0.05). The expansive properties of the bullet significantly increase the area of the bullet hole by 14.87-31.2 times compared to non-hollow point ammunition. Increasing the caliber of the non-hollow point bullet leads to a significant increase in the area of the sagittal section of the residual wound cavity in 1.59-2.03 times; whereas the expansive properties of the bullet do not significantly affect either the perimeter or the area of the sagittal section of the residual wound cavity. For non-hollow point bullets, the volume of the residual wound cavity is more correlated with the caliber of the bullet (increases by 3.36 times); whereas for an hollow point bullet, its caliber has a smaller effect on the volume of the residual cavity (increases by 1.37 times). The expansive properties of the bullet affect the volume of the residual wound cavity in two ways: for 5.45 mm bullets the residual wound cavity increases 1.49 times, for 7.62 mm bullets it decreases 1.65 times. The use of hollow point bullets of 7.62 mm leads to greater collateral damage (zone of secondary necrosis, molecular shock) due to the scattering of the kinetic energy of the bullet to the elastic deformation of near-woundary tissues compared to non-hollow point analogues. The use of 5.45 mm expansive bullets leads to the formation of a larger volume of irreversible damage due to plastic deformation compared to non-hollow point analogues. Conclusions. The resulting model of plastic deformation of soft tissues, depending on the type of modern small arms, showed the dependence of the spatial configuration of the inlet bullet hole, residual wound cavity and deformation and fragmentation of the bullet on the caliber of the cartridge and its expansive properties. Key words: terminal ballistics; wound ballistics; gunshot wound; wound canal; hollow point bullets; plastic deformation; residual wound cavity.

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/m 2 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/m 2 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.

Hybrid rocket engines (HREs) are a chemical propulsion system that nominally combine the advantages of liquid-propellant rocket engines (LREs) and solid-propellant rocket motors (SRMs). HREs in some cases can have a higher specific impulse and better controllability than SRMs, and lower cost and engineering complexity than LREs. For HREs and SRMs, both kinds of rocket engine employ a solid fuel grain, and the chosen grain configuration is a crucial point of their design. Different grain configurations have different internal ballistic behavior, which in turn can deliver different engine performance. A cylindrical grain design is a very common design for SRMs and HREs. A non-cylindrical-grain is a more complex grain configuration (than cylindrical) that has been used in many SRMs, and is also a choice for some HREs. However, while an HRE and an SRM can employ the same fuel grain configuration, the resulting internal ballistic behavior would not be expected to be the same. Pressure-dependent burning tends to dominate in SRMs, while axial flow-dependent burning tends to dominate in HREs. To help demonstrate in a more direct manner the influence of the differing combustion processes on the same fuel grain configuration used by an HRE and SRM, a number of internal ballistic simulations are undertaken for the present study. For the reference SRM cases looked at, an internal ballistic simulation program that has the capability of predicting head-end pressure and thrust as a function of time into a simulated firing is utilized for the present investigation; for the corresponding HRE cases, a simulation program is used to simulate the burning and flow process of these engines. For the present investigation, the two simulation programs are used to simulate the internal ballistic performance of various HREs and SRMs employing comparable cylindrical and non-cylindrical fuel grain configurations. The predicted performance results, in terms of pressure and thrust, are consistent with expectations that one would have for both propulsion system types.

Most chemical reactions promoted by light and using a photosensitizer (a dye) are subject to the phenomenon of luminescence. Redistribution of light in all directions (isotropic luminescence emission) and in a new spectral range (luminescence emission spectrum) makes experimental and theoretical studies much more complex compared to a situation with a purely absorbing reaction volume. This has a significant impact on the engineering of photoreactors for industrial applications. Future developments associated with photoreactive system optimization are therefore extremely challenging, and require an in-depth description and quantitative analysis of luminescence. In this study, a radiative model describing the effect of luminescence radiation on the calculation of absorptance is presented and analyzed with the multiple inelastic-scattering approach, using Monte Carlo simulations. The formalism of successive orders of scattering expansion is used as a sophisticated analysis tool which provides, when combined with relevant physical approximations, convenient analytical approximate solutions. Its application to four photosensitizers that are representative of renewable hydrogen production via artificial photosynthesis indicates that luminescence has a significant impact on absorptance and on overall quantum yield estimation, with the contribution of multiple scattering and important spectral effects due to inelastic scattering. We show that luminescence cannot be totally neglected in that case, since photon absorption lies at the root of the chemical reaction. We propose two coupled simple and appropriate analytical approximations enabling the estimation of absorptance with a relative error below 6% in every tested situation: the zero-order scattering approximation and the gray single-scattering approximation. Finally, this theoretical approach is used to determine and discuss the overall quantum yield of a bio-inspired photoreactive system with Eosin Y as a photosensitizer, implemented in an experimental setup comprising a photoreactor dedicated to hydrogen production.

This chapter provides an overview of the relevant literature on simulation and modeling of composites used for protection against ballistics and blasts. This chapter presents three case studies related to personal safety and protection using composites subjected to ballistic and blast loads: (1) numerical simulation of high-velocity bullet impact, (2) numerical simulation and effect of deflector composite geometry on blast protection, and (3) simulation and experimental comparison of a personal protective boot against mine blasts using frangible leg model, both experimentally and numerically.

In the field of ballistics, Johnson-Cook (JC) plasticity and fracture models have provided a good theoretical basis for the prediction of ballistic performance by capturing the essence of ductile metal fracture. Nevertheless, the JC model cannot accurately reproduce the fracture behaviour of some metals. Many Lode parameter-dependent fracture criteria have effectively improved this deficiency, indicating that the fracture loci of these metals are Lode-dependent, even though the flow stress behaviour is stress state dependent, which cannot be well characterized by the JC plasticity model. In this paper, a series of mechanical tests and parallel numerical simulations of ZK61m magnesium alloy were conducted. The results showed that the flow stress behaviour and fracture loci of the alloy were obviously Lode dependent. Therefore, it seems insufficient to evaluate only the necessity of incorporating Lode parameter into a fracture criterion in predicting ballistic performance of ZK61m magnesium alloy, and more investigations on the influence of Lode parameter on the plasticity behaviour of the material should be carried out. In the present work, ballistic tests were conducted on 5 mm thick ZK61m magnesium alloy plates using blunt and ogival nose shaped projectiles with a nominal diameter of 12.68 mm. The targets failed by shear plugging when impacted by blunt-nosed projectiles, but caused a unique failure pattern under the impact of ogival-nosed projectiles. Lode-dependent plasticity model and fracture criterion were adopted. Better prediction accuracy was observed when Lode parameter is considered in both the plasticity model and fracture criterion simultaneously.

The addition of nanofillers in high-performance reinforcement results in the formation of hybrid composites. The objective of this research is to determine the effect of silica nanofillers loading ...

A dynamical moving pressure structural numerical calculation model using the internal ballistics calculation pressure-time results was constituted and the vicinity of the internal ballistics and quasi-internal ballistics structural model was checked. The Von Mises stresses obtained by the dynamical structural numerical model calculations and the Von Mises stresses calculated from the shot test strain measurements were compared. The difference for the worse case was 20% and for the best case was 0.1%. Furthermore, the model gave better agreement for the higher charge masses. The numerical structural quasi-internal ballistics computation model created was verified for the top charge mass which represents the highest stress condition and used in a gun barrel design. Keywords: Gun tube design, Thick wall cylinder, Residual stress, Internal ballistics, Service pressure, Wall thickness, Numerical modeling of internal ballistics

INTRODUCTION: Training using ultrasound phantoms allows for safe introduction to clinical skills and is associated with improved in-hospital performance. Many materials have been utilized to simulate human tissue in phantoms including commercial manikins, agar, gelatin, and Ballistics Gel, however phantom tissues could be improved to provide higher fidelity ultrasound images or tactile sensation. This paper describes a novel phantom tissue mixture of a modified polyvinyl chloride (PVC) polymer, mineral oil, and chalk powder and evaluates needle cutting and ultrasonic properties of the modified PVC polymer mixture compared to a variety of phantom tissues. METHODS: The first experiment measured axial needle forces of a needle insertion into nine phantom materials, including three formulations of modified PVC. The second experiment used a pairwise comparison survey of ultrasound images to determine the perceived realism of phantom ultrasound images. RESULTS: It was found that the materials of Ballistics Gel and one of the PVC mixtures provide stiff force feedback similar to cadaver tissue. Other phantom materials including agar and gelatin, provide very weak unrealistic force feedback. The survey results showed the PVC mixtures being viewed as the most realistic by the survey participants, while agar and ballistics gel were seen as the least realistic. CONCLUSIONS: The realism in cutting force and ultrasound visualization was determined for a variety of phantom materials. Novel modified PVC polymer, has great potential for use in ultrasound phantoms because of its realistic ultrasound imaging and modifiable stiffness. This customizability allows for easy creation of multilayer tissue phantoms.

International audience; Grain growth has a definitive impact on the quality of transparent sintered materials in areas such as ballistics, biomaterials, jewelry, etc. Controlling the sintering trajectory at the precise moment of final stage sintering is one of the main sintering challenges for obtaining highperformance, fully-dense nano-ceramics. However, the final stage of sintering involves a very complex coupling between the rate of porosity elimination/grain growth and transition mechanisms. This complexity makes predicting the sintering trajectory very difficult, and most transparent material production escapes this problem by using expensive high-pressure methods such as hot isostatic pressing (HIP). In the quest for a pressureless transparent material process, this paper addresses the challenge of predicting grain growth in the transition domain from the grain growth onset (in a high porosity region) to full density for MgAl 2 O 4 spinel. We present a comprehensive modeling approach linking theoretical models such as Zhao & Harmer's and Olevsky's equations to accurately predict the complex grain growth transition region of final stage sintering. This modeling approach opens up the possibility for numerical exploration of microstructure development via underlying kinetics experimental identification.

Dynamic impact tests using thin metal plates for ballistic characterization have received significant attention in recent years. The Johnson&ndash, Cook (J&ndash, C) model is extensively used in numerical modeling of impact and penetration in metals. The AISI (American Iron and Steel Institute) 301 steel family presents good impact behavior, excellent formability, and high corrosion resistance. Thus, NICRO (Nickel and Hard Chrome Plated Steel) 12.1 (part of the AISI 301 steel family) was chosen in this work, although parameters of the J&ndash, C model or impact results were not found in the literature. In this work, NICRO 12.1 steel plates, were characterized in ballistics with an initial impact velocity up to 200 m/s and three shape nose projectiles. The Johnson&ndash, Cook parameters for the NICRO 12.1 steel were calculated for a large range of temperatures and strain rates. Impact tests were carried out using three projectiles: conical, hemispherical, and blunt. The ballistic curves, failure mode, and maximum deformation obtained with each projectile, experimentally and numerically, were compared, and a good correlation was obtained.

Up until the Industrial Revolution, the dynamic mechanical properties of materials were only of importance in warfare, particularly after the powder-driven gun was invented. With the invention of the steam engine, the explosion of steam boilers (which is similar to the explosion of cannon) became a concern. When railways began to be built, the lack of knowledge of the dynamic properties of the iron alloys used in rails and railway bridges was understood to be a problem, but no way of measuring them was devised until the end of the nineteenth century. Ingenious mechanical (and later electromechanical) methods of recording signals onto rotating drums or moving smoked glass plates began to be developed from the middle of the nineteenth century onwards. Optical/photographic methods of recording information from dynamic experiments date from the 1890s. The rod-on-anvil technique (later named after Taylor) was developed in France at the beginning of the twentieth century but not mathematically analysed until the 1940s. The Hopkinson pressure bar was invented just before the start of the First World War and found to be useful in improving British artillery shells. It was then forgotten about until the Second World War when a two-bar version was developed for measuring the dynamic properties of soft materials such as explosives and polyethylene. As the story of high rate mechanical testing from about 1950 onwards is quite well known to the high rate testing community, this date is taken as the end point of this article.

Performance evaluation of artillery gun system is carried out during the dynamic firing of armament stores. The recording of different ballistics parameters during dynamic firing plays an important role in assessment of armament stores. For characterization of internal ballistics of a gun and propellant, the velocity-time profile of the projectile and associated chamber pressure inside the barrel are two of the most crucial parameters. This paper presents details of measurement of in-bore velocity-time profile using Doppler radar systems. From the velocity time profile, acceleration-time profile has been obtained and subsequently base pressure and breech pressure time profiles have been calculated. The paper also deals with the effect of charge mass decay profile with time during combustion of propellant on computation of breech pressure-time profile. The average error observed between measured peak breech pressure from piezoelectric transducer and computed peak breech pressure from in-bore radar data is of the order of 2.3%.

In this research paper, empirical relation between burn rate and pressure index of spherical gun propellant was carried out in the closed bomb. This is double base propellant and used in power cartridge to destroy the suspicious unattended objects. The novelty in this research is that, the author proposed a novel empirical relation among force constant, burning rate coefficient, pressure index and peak pressure. Ballistics properties like burning rate of propellant is depend upon on its shape and size (configuration), chemical composition, temperature, loading density and pressure. The major outcome of this research study has direct relevance for the performance prediction of propellant in the form of powder related to dynamic firings. The peak pressure of the propellant is 235.04 MPa, the rise time 1.95 ms, burn rate coefficient 0.073, pressure index 1.29, flame temperature 2680 0K and force constant 953.2 J/g were obtained during experiment. The burning rate for the spherical gun propellant is experimentally expressed as 1.29

The naturally aged solid rocket motor is static tested for internal ballistics performance evaluation thus estimating service life. The motor propellant weight is 800 kg and composition is AP/Al/HTPB. After 10 years, propellant samples were cut and taken from motor port region, and test coupons were made from samples; and mechanical properties were evaluated, while ballistic properties determined from static test firing. The mechanical properties test results showed that decrease in tensile strength and elongation and increase in Young’s modulus. The margin of safety on propellant is reduced to 0.3 from 1.0. The aged motor performance was evaluated by full-scale static test firing. The test results show that reduction in ballistics and mechanical properties are due to ageing but no reduction is observed in propellant energy i.e., Isp(delivered). The aged solid rocket motor performed close to lower mission bound and within acceptable limit and the determined motor service life is 10 years.

Estimated damage levels from ballistic impact zones provide valuable information to make bulletproof materials more effective. This study aims to determine the impact of ballistics including deformation and energy absorption in fiber metal laminates (FMLs) that collide with 9 mm FMJ caliber bullets at speeds of 426 m/s. Finite element method modeling is done using ANSYS 18.1 workbench software. The simulation results show that FMLs can hold the bullet rate with deformation on the back of the target (DOPIII) of 8,55 mm and total energy absorption of 426,59 J at 0,000095 s. The combination of two materials, Al 5083 in the outer layer and kevlar/epoxy as the core, results in faster energy absorption and maximum stress concentrations only occur in the kevlar/epoxy so there is no damage to the first and subsequent layers.

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

Most glasses are often exposed to impact loading during their service life, which may lead to the failure of the structure. While in situ experimental studies on impact-induced damage are challenging due to the short timescales involved, continuum-based computational studies are complicated by the discontinuity in the displacement field arising from the propagation of cracks. Here, using peridynamics simulations, we investigate the role of the mechanical properties and geometry in determining the overall damage on a glass plate subjected to ballistic impact. In particular, we analyze the role of bullet velocity, bullet material, and elastic modulus, fracture energy, and radius of the plate. Interestingly, we observe a power-law dependence between the total damage and the fracture energy of the glass plate. Through an auto-regressive analysis of the evolution of cracks, we demonstrate that the self-affine growth of cracks leads to this power-law dependence. Overall, the present study illustrates how peridynamics simulations can offer new insights into the fracture mechanics of glasses subjected to ballistic impacts. This improved understanding can pave way to the design and development of glasses with improved impact-resistance for applications ranging from wind-shields and smart-phone screens to ballistics.

The development of new ultrasound imaging technologies that aim to resolve objects smaller than the conventional ultrasounds diffraction limit calls for new types of phantoms to evaluate these technologies. When it comes to vascular flow phantoms, this becomes challenging due to the difficulty of manufacturing phantoms with vessels smaller than 1 mm in diameter. Here we describe a novel manufacturing method to construct phantoms with micro-vessels with a size down to 88 μm using oil-based clear ballistic gel (Clear Ballistics, Greenville, SC, USA) as surrounding material. Clear ballistic gel is a long-term stable tissue-mimicking material with speed of sound around 1470 m/s.

The use of large gauge (G) spinal anesthesia needles can increase complications due to buckling. The purpose of this study was to quantify the behavior of spinal needles in buckling using a repeatable laboratory model. A spinal anesthesia procedure and buckling complication was reproduced in vitro using a custom test fixture designed to match the boundary conditions of needle insertion as performed by an anesthesiologist and a uniaxial servohydraulic material testing machine (MTS, Eden Prairie, MN). Buckling tests were performed with 22 G Whitacre (Medline Industries, Inc., Northfield IL), SPROTTE® (Pajunk, Norcross, GA), and Gertie Marx (International Medical Development, Huntsville, UT) needles (n = 30) in a ballistics gelatin tissue surrogate (Clear Ballistics, Fort Smith, AR). In analyzing axial force results, critical buckling load results were 27.65 ± 0.92 N, signifying that needle fragility is not why buckling is challenging to detect. Force feedback during needle insertion increased linearly due to frictional forces from the tissue surrogate on the needle. The differential between the resultant insertion force and the critical buckling force is more important to the detection of needle buckling than the critical buckling force alone. A very small difference in these two forces could feel like expected resistance increase as the needle is further inserted into the multiple tissue layers. Comparison of the differential between the resultant insertion force and the critical buckling force should be considered when choosing a needle to best detect and prevent a buckling complication.

Production of ceramic armour solutions on-demand/in-theatre would have significant logistical and military advantages. However, even assuming that such technologies could be successfully deployed in the field, such near net-shape manufacturing technology is relatively immature compared to conventional sintering of ceramics. In this study, the ballistic performance of a series of additively manufactured (AM)/rapidly-prototyped (RP) alumina tiles of 97.2% of the density of Sintox FA™ were investigated using both forward- and reverse-ballistic experiments. These experiments, undertaken with compressed gas-guns, employed the depth-of-penetration technique and flash X-ray as primary diagnostics to interrogate both efficiency of penetration and projectile-target interaction, respectively. The RP alumina was found to exhibit useful ballistic properties, successfully defeating steel-cored (AP) 7.62 × 39 mm BXN rounds at velocities of up-to c.a. 850 m/s, while exhibiting comparable failure modes to conventionally sintered armour-grade Sintox FA™. However, where a

Shear thickening fluids (STFs) are a special class of field responsive non-Newtonian fluids which exhibit transition from low viscosity to high viscosity state when these are subjected to shear deformation, particularly when the shear rate exceeds a critical value termed as the critical shear rate (CSR). Due to this unique characteristic of STFs, these are generally used for vibration mitigation or shock absorbance such as in vibration dampeners, hip protection pads, in protective gear for athletes etc. From the last two decades, STFs have found application in the field of ballistics, particularly in the development of special class of STF-intercalated armours called Liquid Body Armours (LBAs). These new age armours are lighter in weight and more flexible as compared to conventional heavy armours, which, infact seriously affect the mobility and agility of the soldier, especially in combat situations. Although, exhaustive studies are available which show the improvement in impact resistance of STF-treated high performance fabrics, but there are limited studies which explore the efficacy of STF treatment method. In this study, an attempt is made to understand this aspect. The low velocity impact studies were conducted on drop tower machine, while high velocity impact studies were accomplished on in-house designed and fabricated Split Hopkinson Pressure Bar (SHPB) experimental set-up. It was observed that when STF was kept in liquid form between layers of ballistic fabrics, the composite exhibited reduced performance, whereas, STF-treated ballisic composites exhibited enhanced impact toughness at high strain rates in SHPB testing.

From time to time, severe or fatal injuries caused by small caliber air rifle projectiles are seen. In forensic sciences, the theoretical wounding potential of these weapons and projectiles is widely known. Usually, shots against the skull were reported and, in these cases, penetrating the eyes or thin bone layers of the temporal region. Amongst a huge number of different projectiles available for air guns, sub-caliber 4.4-mm (.173) caliber steel ball projectiles were used in an unusual suicide case. This case led to fundamental questions concerning wound ballistics. An 82-year-old man shot once against his right temporal region and twice into his mouth with a 4.5-mm (.177) caliber air rifle. Because of the exceptionally deep penetration of the base of the skull and the use of spherical-shaped sub-caliber air rifle projectiles, terminal ballistic features were analyzed and compared to results published in forensic literature. Test shots using the same weapon and similar projectiles were fired into ballistic gelatin to measure and calculate basic wound ballistic variables of cal. 4.4-mm (.173) steel balls. In comparison, further test shots with cal. 4.5-mm (.177) steel balls BB (ball bearing), flat-headed and pointed air rifle pellets ("diabolos") were carried out. The theoretical penetration depth in solid bone was calculated with 36.4 mm, and test shots in gelatin from hard contact produced an on-average wound track of 120 mm underlining the potential wounding effect. Furthermore, spherical projectiles could roll back and forth within the barrel, and an air cushion between projectile and breechblock can reduce muzzle velocity by more than half, explaining the retained missile in the temporal region.

A novel internal ballistics technique for determining the time-resolved spatially averaged regression rate of the solid-fuel grain in a hybrid rocket engine is presented. This technique makes use o...

In practice of forensic medicine and forensic ballistics there are quite often the cases of different types ofgunshot wounds infliction by atypical damaging elements which were used in illegal independent loading of cartridges to the rifle weapon. The purpose of the researches being performed - studying on a concrete example from criminalistics practice of damaging properties of 7.62 mm rifle bullets of type FMJBT (Full Metal Jacketed Boat Tail) which were used for loading by self-made way cartridges of 7.62 * 39 caliber. Originally, during natural tests in the conditions of a ballistic track the ballistic characteristics of the shot bullets and the value of their ballistic coefficient were established. At the following stage of researches the losses of kinetic energy of rifle bullets on punching blocks of ballistic plasticine with the thickness of 100-140 mm were determined. As a result of tests the character of formation of the damage channel in the thickness of biological tissues simulator is established at the stable and unstable movement of the bullets in the visco elastic medium. Besides, during the researches the values of the parameters necessary for calculations ofpenetration depth of the bullets into a fabric of biological object depending on their speed at the moment of hit in the target, were determined. In particular it was established that at unstable movement of an investigated bullet in thickness of the simulator the value of boundary speed amounts 138.1 m/s, and the value of the medium drag factor - 1.782. Using estimated values offlight speed of the bullets in the trajectory the values of depth wound channels in biological tissues were calculated and the conclusion was drawn on the guaranteed causing of penetrating wounds in all established distances of shooting. Thus, use of the methodfor estimation of damaging properties of investigated bullets, the criterion of which is the length of the wound channel and its boundary value was obviously demonstrated.

An experimental study and hydrocode simulation was conducted to investigate the correlation between hardness of steel and the ballistic performance of steel-encapsulated SiC armour modules against long rod impact. The armour module design composed of a SiC tile in confinement within 10 mm backing and 5 mm cover plates, which were made of AISI 4340 steel with varying hardnesses between HRC 30 to 50. The armour modules were subjected to normal impact by conical tungsten alloy long rods of 8.3 mm diameter and 115 mm length, at a nominal striking velocity of 1.25 km/s. A witness block of AISI 4340 steel was placed behind the armour module to capture the residual projectile. Failure analysis of the armour modules and the measurement of residual penetration in the witness blocks were applied to characterize ballistic performance of the ceramic armour modules. The different modes of failure of the backing plate and its influence on ballistic performance of the module were verified through visual inspection of test modules and analysis of high speed videos. Hydrocode simulation of the experiments using LS-DYNA was carried out to model the penetration and failure processes that occurred in the armour modules. The Johnson Cook model was applied in simulation of the steel confinement, accounting for the influence of hardness on JC model parameters. Results showed that increasing hardness of the backing enhanced the performance of the module while cover plate hardness had no influence within the range of hardnesses tested. This study paves the way for future studies to further understand the influence of steel hardness on the ballistics performance of steel-encapsulated silicon carbide (SiC) armour modules.

Soft body armour panels have been developed by tuning the structure of 3D woven orthogonal aramid fabrics and reinforcing them with shear thickening fluid (STF). Five 3D woven orthogonal aramid fabric structures were prepared by changing the ratio of stuffer (X direction) to binder (Z direction) yarns and also by changing the relative position of the latter. Two types of ballistic evaluations, namely energy absorption against low velocity (165 ± 10 m s −1 ) bullets and back face signature (BFS) against high velocity (430 ± 10 m s −1 ) bullets were carried out for neat and STF impregnated 3D fabrics and their panels. STF impregnation improved impact energy absorption by 3D woven aramid fabrics. Increasing the ratio of stuffer to binder yarns was found to be beneficial in terms of impact energy absorption and resistance against bullet penetration. STF impregnated 3D fabrics having 4:1 stuffer to binder ratio performed the best in ballistic evaluations. Synergistic effect of 3D woven fabric structure and reinforcement of STF was found to be the key for successful design of soft body armour.

Recent microscale ballistic experiments have revealed that multilayer graphene membranes exhibit exceptionally high ballistic limit velocity and specific penetration energy. A key feature contributing to the exceptional performance of these systems is the cone wave that develops at impact, which propagates radially at a very high speed for ultra-light and stiff graphene membranes, distributing the kinetic energy of the projectile away from the impact zone. Current theories on ballistic impact consider infinitely wide membranes, and atomistic simulations involve very small projectiles and specimen dimensions, and thus cannot ascertain whether microscale ballistics observations are scalable and size-independent. Here, we discover a particular size effect due to the reflection of cone wave that has not been previously observed or considered. We present molecular dynamics simulations showing that there exists a critical membrane size below which the cone wave reflections from the boundaries induce perforation; a phenomenon that is particularly relevant for microballistic testing of graphene membranes. We present an analytical relationship, verified by simulation data, which predicts the critical membrane size simply as a function of the projectile size, membrane thickness and the ratio of the projectile and membrane densities. Our findings provide timely guidance for future microscale experiments and atomistic simulations for accurate characterization of the impact performance of 2D nanomaterials.

Dual-thrust solid propellant rocket motors are used in applications where the vehicle is boosted with a high thrust to reach very quickly a high speed that is then sustained by a low thrust. Dual-t...

Materials used in military applications have to withstand multiple threats like ballistics and explosions. Thus, high-strength low alloyed (HSLA) steels are used. The main joining technique for metals is welding. Therefore, analysing the dynamic impact behaviour of high-strength welds is very important to fulfil these demands. Investigation of welds at high strain rates has rarely been conducted in the past. To determine the dynamic impact behaviour of hybrid laser-arc welds, the Split Hopkinson Pressure Bar (SHPB) technique was used. The base material was a quenched and tempered fine-grained armour steel with yield strength of 1100 MPa. First, a full hybrid laser-arc weld was investigated by extracting specimens consisting of weld metal and heat affected base material. The influence of two variables, the cooling time between 800 °C and 500 °C (t 8/5 ) and strength of filler material, on the impact behaviour was studied. The cooling time t 8/5 was varied by preheating to influence the microstructure in the HAZ and to analyse the effect on the hardness and dynamic compressive strength. Subsequent analysis to detail the original investigation was carried out by dilatometer heat treatment of specimens to create homogenous subzones of the weld. These specimens have a homogenous microstructure of HAZ and were tested by SHPB to determine the stress-strain characteristics for the different microstructures of HAZ. The results of the weld specimen showed the effect of preheating and filler material strength on the dynamic compressive behaviour. The analysis of the different microstructures of the HAZ indicated that especially the tempered microstructure caused a reduction in dynamic compressive strength.

Estimated damage levels from ballistics impact zone provide valuable information to make bulletproof materials more effective. Therefore, this study aims to determine the impact of ballistics including hole shape, hole depth, macro, and microstructure on fiber metal laminate. The characteristics of ballistics impact for each configuration target is obtained from experiment and comparison based on simulations with finite element method. Test experiments used short-barreled fire guns at a distance of 5 meters with a normal attack angle based on the National Institute of Justice standard. Simulation with Johnson-Cook plasticity models for aluminum plate and orthotropic material model for kevlar/epoxy. The experiment and simulation results showed that the projectile is able to perforate the first layer (aluminum plate) and the second layer (Kevlar/epoxy) while the last layer (backplate) is deformed to form a bulge. The aluminum plate is perforated by the failure of petaling formation on the backside and spread of dimple fracture around the area of the petal which indicates ductile fracture while kevlar/epoxy is perforated by projectile with failure of fiber fracture on primary yarn, fiber pull-out, fiber stretching and fiber rupture.

Significant growth in knowledge about metal additive manufacturing (AM) affects the increase of interest in military solutions, where there is always a need for unique technologies and materials. An important section of materials in the military are those dedicated to armour production. An AM material is characterised by different behaviour than those conventionally made, especially during more dynamic loading such as ballistics testing. In this paper, M300 maraging steel behavior was analysed under the condition of ballistic testing. The material was tested before and after solution annealing and ageing. This manuscript also contains some data based on structural analysis and tensile testing with digital image correlation. Based on the conducted research, M300 maraging steel was found to be a helpful material for some armour solutions after pre- or post-processing activities. Conducted solution annealing and ageing increased the ballistic properties by 87% in comparison to build samples. At the same time, the material’s brittleness increased, which affected a significant growth in fragmentation of the perforated plate. According to such phenomena, a detailed fracture analysis was made.