34TH INTERNATIONAL SYMPOSIUM ON BALLISTICS
34th International Symposium on Ballistics
ADAPTIVE OPTIMISATION OF EXPLOSIVE REACTIVE ARMOUR FOR PROTECTION AGAINST KINETIC ENERGY AND SHAPED CHARGE THREATS
We evaluate an adaptive optimisation methodology, Bayesian optimisation (BO), for designing a minimum weight explosive reactive armour (ERA) for protection against a surrogate medium calibre kinetic energy (KE) long rod projectile and surrogate shaped charge (SC) warhead. We perform the optimisation using a conventional BO methodology and compare it with a conventional trial-and-error approach from a human expert. A third approach, utilising a novel human-machine teaming framework for BO is also evaluated. Data for the optimisation is generated using numerical simulations that are demonstrated to provide reasonable qualitative agreement with reference experiments. The human-machine teaming methodology is shown to identify the optimum ERA design in the fewest number of evaluations, outperforming both the stand-alone human and stand-alone BO methodologies. From a design space of almost 1800 configurations the human-machine teaming approach identifies the minimum weight ERA design in 10 samples. This is an extended abstract of a paper published in Defence Technology.
PHYSICS INFORMED NEURAL NETWORK (PINN) FOR TRAJECTORY ESTIMATION OF ARTILLERY SHELLS FROM TARGET LOCATION
Traditional artillery operations rely on pre-computed range tables to determine optimal gun settings for engaging enemy targets. This study presents a novel approach that replaces range tables with inverse optimization of a modified point mass model, leveraging Physics-Informed Neural Networks (PINNs). The proposed neural network estimates aerodynamic coefficients along the trajectory of a 155 mm projectile (modified M107) using only measured trajectory coordinates from a single test fire. This eliminates the need for extensive range tables, resulting in significant cost savings and reduced computational effort. Furthermore, the system predicts gun parameters and projectile trajectory with an error less than or equal to by coupling the modified point mass model with a second PINN trained solely on enemy target location data. This integrated approach enhances targeting precision while offering a cost-effective and efficient alternative to conventional artillery trajectory estimation methods.
AI-SUPPORTED COMPUTATIONAL COMBUSTIBLE CARTRIDGE CASE DESIGN
AI-supported combustible cartridge case (CCC) design by expert system represents an innovative approach that addresses the inefficiency and inaccuracy in present CCC production design practices. Traditional CCC production design focuses mainly on its dimensions and mechanic strength, and few considerations are in its comprehensive properties, such as the relationship between composition, dimensions, microstructure and burning rate. This paper proposes a novel AI-supported CCC design expert system based on a computational model on the CCC production parameters and its burning rate. Initially, principal component analysis was employed to combine the chemical components of CCC to reduce the dimensionality of CCC production parameters, thereby facilitating the establishment of AI-supported computational match model of CCC design. Subsequently, the data acquired during the CCC production process was input into the K-means clustering algorithm to cluster the data into several clusters in order to screen necessary data used in the match model. Ultimately, the trilinear/ Radial Basis Function (RBF) interpolation method integrated in the expert system was used to calculate the production parameters according to the means of the clusters obtained from the K-means clustering algorithm. Thus, the established AI-supported computational CCC design method can streamline the experimental process, elucidate the relationship between CCC production parameters and its burning rate and facilitate the inverse design of CCC manufacturing parameters. This research provides a data-driven method for accurately and efficiently computating CCC manufacturing parameters, offering valuable insights for the design and development of high-performance CCC. It paves a transformative way for CCC formulation and structural design and is of great scientific significance.1
ARTIFICIAL NEURAL NETWORK FOR DAMAGE PREDICTION AT HYPERVELOCITY IMPACTS
Impact of a projectile on a thin bumper at hypervelocity causes perforation. Primary fragment in residual projectile debris becomes a threat to main structure. Complexities in damage assessment arise due to changing phenomenology with impact conditions. Conventionally, damage assessment by empirical models has been developed based on experiment and simulation data. However, models have limited versatility. Artificial neural network (ANN) has advantages in adaptive learning from data and in solving complex problem to reach approximate solution. In this article, networks are trained for estimation of perforated hole dimensions and primary fragment characteristics (mass, velocity and exit angle). In certain range of impact parameters, estimated values of those models are deviating, while ANN indicates changing damage trend as per simulation data. To improve ANN estimates, additional simulations are performed. The networks are retrained and compared. It is observed that ANN requires less data for training with better accuracy.
WARHEAD PERFORMANCE OF THE GERMAN FLYING BOMB (V1) IN WORLD WAR TWO
The warhead performance of the German Flying Bomb (V1 - Vengeance Weapon) also known as Fieseler (Fi-103) and Flakzielgerät 76 (FZG-76) is assessed; the V1 was the world’s first cruise missile. The V1 was cost effective, being cheap and easy to produce. The number of design changes of the build and particularly of the warhead filling composition make analysis difficult. This paper aims to add some detail to this area. During the war many replacement fillings were used as alternatives. All the filling types and associated London Housing damage are assessed. These large areas of damage caused major problems for the British. The performance difference between the various warhead compositions was large, with a factor of four between the best and worst charges used. The fact that air raid warnings could be given disrupted many lives, especially during the night, seriously affecting wartime industry.
GRID DEPENDENCE OF JET CUT-OFF VELOCITY IN SHAPED CHARGE PENETRATION
Estimation of depth of penetration in a Rolled Homogenized Armor (RHA) using numerical simulations is tedious task. The numerical simulations tend to give more depth of penetration than actual. The cut-off velocity is used to compensate this difference. In present work, cutoff velocities are estimated for standard Ballistic Research Laboratory (BRL) shaped charge. The sensitivity of these cut-off velocities to grid size is also studied. Afterwards, these cut-off velocities are used to estimate depth of penetration of in-house shaped charge and compared with experimental results which are in close agreement with estimated value.
NUMERICAL SIMULATION TO ESTIMATE DELAY BETWEEN PRECURSOR AND MAIN SHAPED CHARGE WARHEAD
Modern day's tanks are protected by an Explosive Reactive Armor (ERA) to provide enhanced protection. Tandem warhead is used to defeat the ERA. It comprises of a small shaped charge warhead (generally called precursor warhead) which is placed in front of Main shaped charge warhead. After initiation of precursor warhead, explosive gases from precursor warhead along with the debris of precursor warhead and other components (if any between Precursor warhead and main warhead), starts expanding and accelerate towards Main warhead. Main warhead should be initiated at an appropriate time so that gases and debris from the precursor do not hinder with jet formation process of Main warhead or cause any structural damage to it. In addition, initiation of Main warhead should be delayed so as to give enough time for clearing of ERA plates in front of target. It is always desirable to initiate main warhead with an optimized time delay. Time delay between initiations of these two shaped charge warheads, play a vital role in performance of main warhead. Time delay depends on design of precursor warhead, distance between two warheads and also on components placed in between them which serves as obstacles to the expending gases. This article is focused on numerical simulations for estimating initiation time delay between two warheads using LSDyna software along with experiments carried out to validate the estimated delay.
INVESTIGATION OF SHOCK WAVE PROPAGATION IN SOFT TISSUE SIMULANTS: AN ANALYSIS OF BALLISTIC GELATIN AND SYNTHETIC BALLISTIC GEL
This study investigates the effects of shock waves on soft tissue simulants, focusing on ballistic gelatin and a synthetic ballistic gel. Although extensive research has focused on the mechanical properties of soft tissue simulants, their behavior under shock wave conditions, such as those caused by blasts, is less understood. As explosives are increasingly used in modern combat scenarios, it is essential to study how shock waves interact with soft tissue. This knowledge is crucial for improving protective equipment and evaluating blast effects on the human body. A two-phase methodology was applied: First, ballistic gelatin production and synthetic gel composition were analyzed, identifying uncertainties and measuring sound speeds at varying temperatures to align with human tissue properties. Second, simulants were subjected to free-field shock waves, and embedded pressure sensors captured wave propagation, peak overpressures, and propagation velocity. Findings provide comparative insights into simulants’ shock wave responses, offering a foundation for future experimental setups.
COPPER LuREx: COMPARISON OF THE FRAGMENTATION OF COPPER- AND STEEL-CASED EXPLOSIVE DEVICES
Data from safety justification trials (SJTs) and calculations are used to predict the threats to the facility infrastructure from explosively-driven experiments. We aim to remove the requirement for future costly SJTs and rely solely on simulation, which necessitates validation and verification of our modelling methodology. To improve our fragment formation modelling and to test mitigation schemes, a range of simple steel-cased explosive devices have been designed and fielded in experiments. The devices were designed using leadingedge modelling techniques and gave us information regarding fragment formation and rotation. There were, however, some surprises in the results from these early trials. The LuREx (Lucille Radiographic Experiment) was a modified version of one of these devices which successfully allowed us to probe the early-time formation of fragments after crackformation has completed. Following on, a second device using a copper case (CLuREx) has been conducted to study fragmentation in a different, more ductile, metal.
APPLICATION OF GURNEY AND FLIGHT OF FRAGMENT CALCULATIONS FOR WATER JET VELOCITIES IN EXPLOSIVE APPLICATIONS
This study examines the use of Gurney equations, typically applied to metal fragment velocities, in modeling water jet behavior in percussion actuated non-electric (PAN) disruptors, tools for improvised explosive device neutralization. Experimental tests used three charge strengths (2.59, 5.83, and 7.13 grams) and two configurations: standard (full-barrel water load) and “negative 8” (partial water load). High-speed footage captured water column velocities, which were compared to predictions from infinitely tamped and open-faced Gurney models and flight of fragment calculations. Results showed that higher charge strengths increased velocity and stability, with the model closely predicting velocities, deviating by as little as 1.4% for standard charges and 2.8% for negative 8 charges. Flight-offragment predictions were most reliable at distances of 0.46 m for standard charges and between 0.61 and 0.91 m for Negative 8 charges. These findings improve understanding of Gurney model applications to fluids.
COMPUTER TOMOGRAPHY-BASED FRAGMENTATION ANALYSIS OF REACTIVE MATERIALS
A novel experimental method analyzes the fragmentation patterns of Reactive Structural Materials (RSMs) as a function of velocity and time. The approach combines a soft-catch medium with computed tomography. This results in high-resolution, three-dimensional reconstructions of individual fragments, including their internal structural integrity. Zirconium cylinders perforate 7075 aluminum target plates, and the resulting fragmentation patterns were examined. The method demonstrated high accuracy, revealing the progression of zirconium damage patterns with increasing velocity. Furthermore, it is shown that additional reaction time had no influence on the examined fragments. This approach offers a tool for investigating the relationship between impact-induced energy release in RSMs and their fragmentation mechanisms, providing insights into their dynamic behavior.
HYPERVELOCITY IMPACT INITIATION: CHALLENGING V2D
Shaped charge jet impact initiation tests on the TDW “standard charge” were conducted using different shaped charges ranging from 44 mm to 200 mm in caliber. These results were in clear contradiction to the widely accepted “v²d rule” which assumes that the critical stimulus S = v²d to initiate an ammunition is a constant – independent from the shaped charge caliber. The extended evaluation of the experimental results exhibited a strong relationship between jet diameter and stimulus for a higher order reaction. Including further results from projectile impact tests still shows a consistent picture. However, for the development of a new “unified” initiation model, the transition from shaped charge jet impact initiation phenomenology to projectile impact initiation phenomenology must first be investigated experimentally.
EVOLUTION OF TANK ARMOUR BASED ON LESSONS LEARNED FROM THE WAR IN UKRAINE
In the response to the threat of drones and top-attack missiles in the Ukraine war attempts were made (on both sides of the conflict) to quickly (and not necessarily in a standardized way) introduce modifications to tank protection systems. Additional armor systems were used for the upper turret and upper hull areas - characteristic steel frames placed at some distance from the surface of the tank with additional explosive reactive armor (ERA) modules mounted. The evolution of such systems, principles of operation and the mechanisms for defeating SCJs were analyzed in the paper. Using a combined experimental and numerical study (in Impetus AFEA software), the protective effectiveness of such solutions against threats from improvised PGdrones and their warheads was evaluated. The effect of warhead attack angle on armor performance was determined.
THE EFFECT OF THE MICROSTRUCTURE ON THE EFFICIENCY OF SHAPED CHARGES OBTAINED VIA POWDER METALLURGY
The presented study is focused on the investigations of the microstructure of shaped charges produced through powder metallurgy using different mixture of tungsten and copper powders. The powders were obtained using different methods as well as the final products were obtained using various processes to ensure best combinations leading to the object with suitable properties. The performed studies were done using the scanning electron microscope equipped with the energy dispersive X-ray spectroscopy system (EDS). The grain size, distribution of the individual elements and their content were analyzed. The research demonstrated the microstructural differences between obtained shaped charges. It is believed that optimizing the microstructure can significantly enhance the penetration capabilities of shaped charges, making them more effective in military and industrial applications. Future work aims to further refine these parameters to achieve even greater performance.1
A NOVEL COUPLED FE/SPH APPROACH FOR SHAPED CHARGE MODELING
A novel approach for modeling shaped charges is presented, using Finite Elements for the high explosive and Smoothed Particle Hydrodynamics for the liner. The performance of the method is compared with classical Computational Fluid Dynamics modeling of high explosives for the test case of a 79 mm shaped charge. The classical and new method are compared with each other and with experimental results. While both modeling techniques provide good overall results with minor shortcomings, the new approach provides better accuracy in modeling the jet tip velocity, while requiring only half the runtime. In combination with the easy integrability of finite element models into larger models, the new approach seems to be a promising future method.
FRAGMENTATION SIMULATION OF ANNEALED AND HARDENED STEEL CYLINDERS USING AN ADVANCED MESHLESS NUMERICAL METHOD INTEGRATING A FRACTURE MODEL ADDRESSING TENSILE AND SHEAR FAILURE MODES
The natural fragmentation of ductile steel cylinder-shape explosive charges has been modelled on ABSTRAO software by means of a tailor made model combining physical descriptions of involved mechanisms and a modern Smooth Particle Hydrodynamics (SPH) method. This numerical approach differs from conventional Finite-Elements Methods-based calculations by being mass-conservative and by applying no constraint to fracture paths while overcoming tensile instability typical of standard SPH formulations. Within this software environment, the tensile mode I fracture and the mode II adiabatic shear bands-induced failure mechanisms are synchronously addressed by dedicated models based on relevant parameters fitted through an experimental comprehensive approach. These damage effects are focused around strain localizations induced by a correlated stochastic distribution of the material yield stress, this distribution accounting for volume defects. Comparisons between numerical and experimental fragments matrices are quite satisfying, highlighting the relevance of the proposed model.
MASSIVELY PARALLEL EXTENSION OF THE GAMMA-SPH APPROACH FOR DEFENSE APPLICATIONS
High velocity impact simulations are critical for designing defense and space systems, but conventional numerical methods struggle with complex geometries. The meshless approach, particularly Smoothed Particle Hydrodynamics (SPH), offers an alternative by handling large deformations and arbitrary shapes. However, SPH faces issues like instabilities leading to numerical inaccuracies. The gamma-SPH scheme addresses these challenges by enhancing stability and accuracy, eliminating spurious oscillations, and tackling tensile instability. This improved method has been successfully applied to simulate shaped charge interactions with explosive reactive armor using a single GPU implementation. The defense industry's need for computational efficiency has driven the development of a high-performance computing (HPC) version of gamma-SPH, optimized for parallel processing. Achieving approximately 92% scaling efficiency on hundreds of GPUs, this HPC version significantly reduces simulation time and processes billions of particles, offering unparalleled capabilities for defense applications like shaped charges, concrete penetration and natural fragmentation.
NUMERICAL STUDY ON TANDEM SHAPED CHARGE AGAINST DIFFERENT GENERATIONS OF ERA
TDW patented in 1974 a solution 1 using a precursor charge neutralizing the ERA protection by initiating the explosive cassette, so that the main shaped charge can now penetrate through the main armor with limited disturbance. A theoretical study of designing a small-caliber TSC warhead by Ling et al.2 reviews relevant design aspects. In this article, we choose a different approach. We created a generic tandem shaped charge to use as reference. Then we used recent development in γ-SPH at ABSTRAO to numerically study the interaction of our reference TSC with each of the three generations of ERA. The principles of operation as well as mechanisms of defeating SCJ by various types of ERA modules were analyzed. Protection capability of different ERA armor solutions was compared. The effect of TSC attack angle and time delay on armor performance was determined.
ELECTROMAGNETIC LAUNCHER ACCELERATES REACTIVE MATERIALS
Reactive materials (RM) are inert under ambient conditions, but release considerable amounts of energy when subjected to appropriate stimuli, such as the large stresses that occur during an impact. While the expression RM covers a broad range of materials, there are components which show similar structural integrity as steel and are called reactive structural materials (RSM). The RSM enhanced warheads function by detonating and accelerating their shrapnel or preformed fragments. The RSM fragments impact a secondary target, and in addition to their kinetic energy, the fragments release chemical energy upon impact, such as heat T and pressure p. This chemical energy release is often referred to as impact induced energy release (IIER). With comparable density and mechanical properties to conventional fragmentation materials, using RSM results in an increased power density. In order to understand and quantify the IIER, high velocity impact (HVI) tests are performed were RSM are launched against defined targets. The RSM are fragments of cylindrical shape with a diameter D=5 mm and a length L=5 mm made of ferrocerium. This study demonstrates the advantage of employing the electromagnetic (EM) launcher, also known as rail gun to accelerate RSM. The EM launcher uses the Lorentz force for the acceleration as the acceleration profile can be defined by shaping the timedependent current accordingly. In this study, the RSM projectiles should reach a certain vi when varying acceleration profiles are applied in order to investigate the dependence of the way of acceleration on the IIER. We present the first results of a cylindrical RSM fragment, made of the brittle ferrocerium material, impacting a t=2 mm aluminium plate in a pressure vessel. The IIER is measured by the pressure increase inside the confined volume to measure, how the different acceleration profiles have an influence on the energy release, even if the RSM kinetic energy is constant. The aim of this project is to test characterisation methods for the acceleration of RSM, and to investigate if the acceleration has an influence on the RSM’s energy release.
MORE ON HIGH OBLIQUITY IMPACT AND EXPLOSIVE INITIATION
The initiation of covered high explosives (HE) upon impact was studied employing 3D numerical simulations, based on experimental calibration, where emphasis was placed on very high obliquity impact angles, close to the ricochet angle. Two distinct initiation models were used and compared in the work, ignition and growth model (IG) and, the Temperature Dependent Reaction Rate (TDRR) initiation model. A comparison is made between the initiation prediction of the two models at the very high obliquities regime. As the impact obliquity increases, the vertical component of the impact velocity decreases while the tangential component increases, raising the overall impact velocity needed for HE initiation in all cases. However, as the impact obliquity continues to increase, an anomaly in the impact velocity needed for initiation, where both the normal and the tangential components increase to achieve initiation, is observed in both models.
SLIPPAGE OF ARAMID FABRICS IN BLAST AND BALLISTIC IMPACT TESTS. FINITE ELEMENT MODELLING METHODS AND CONSEQUENCES IN BALLISTIC RESISTANCE
The sliding of samples in blast and ballistic impact tests is a frequently reported phenomenon. The inward response of materials to out of plane impulsive loads results in reaction forces from the boundaries that exceed, temporarily, the clamping forces. In this work, Aramid fabrics are subjected to blast loading tests for characterizing the magnitude of their slipped boundaries from a circular clamping device. A Finite Element model describing a mesoscale Aramid Fabric with conditional frictional sliding boundaries subjected to blast loads is developed based on the experimental results. A second model configured for ballistic impact is developed in order to quantify the influence of slippage in the ballistic performance. The results reveal that more energy is absorbed when slippage is considered.
THE ASSESSMENT OF A MODELLING TOOL TO RAPIDLY PREDICT THE EFFECTIVENESS OF EXPLOSIVE REACTIVE ARMOUR
A study has been conducted by Frazer-Nash and Dstl to use high-fidelity numerical simulations to assess a Shaped Charge (SC) vs Explosive Reactive Armour (ERA) Fast Running Engineering Model (FREM). The SC vs ERA FREM utilises predictive correlations from open-source literature to estimate the residual penetration of a SC-ERA interaction. High-fidelity numerical simulations were developed in LS-DYNA, which allowed for a detailed assessment of each equation utilised by the FREM. It was shown that the FREM successfully identified most of the interactions between a SC jet and ERA, however, discrepancies were observed between FREM and LS-DYNA outputs when comparing residual penetration depth predictions. An interrogation of the FREM identified the equations which contributed most to this variation, with recommendations provided on ways to improve them. The study determined that with these improvements implemented, and through further validation, the ERA FREM could be developed into a rapid tool for generating suitably accurate predictions of ERA performance against a SC.
APPLICATION OF TRACKING DOPPLER RADAR IN MISSILE FRAGMENTS VELOCITY MEASUREMENT AFTER MID-AIR DETONATION
The following paper presents a possibility of tracking radar in estimating of velocity of HE warhead fragments after detonation. The velocity of fragments is extreme important in the armament technology. Fragments’ velocity indicates effectiveness of HE warheads. The higher velocity, the deeper perforation of armors. The effective range of warhead also increases with velocity. There are a few methods for estimating fragments velocity. Most of them rely on stationary fragmentation of warhead in a special testing spot. The following paper presents different approach. Fragmentation of warhead in that matter occurs in the air during proper trajectory of flight. The paper presents: the advantages and disadvantages of that method, description of the field experiment with live warhead, collected measured data and analysis of them.
POST-BLAST RESIDUAL CAPACITY OF REINFORCED CONCRETE COLUMN: A NUMERICAL STUDY
The failure of engineering structures due to frequent blast incidents results in significant fatalities and economic losses and must be designed to resist such tragic events. RC columns are critical structural elements, failure of which can cause progressive collapse. This study evaluates the post-blast residual capacity of the RC column using the finite element (FE) model in LS-Dyna. Parameters such as scaled distance, and initial axial load ratio are utilized to evaluate blast and subsequent quasi-static loading response. The residual axial capacity and flexural capacity at different levels of axial load are evaluated. The results indicate that both peak and mid-span deflection reduce with an increase in the scaled distance. The effect of initial axial load at a lower scaled distance is minimal, whereas significant improvement is observed for a higher scaled distance. Also, residual lateral load capacity increases with an increased level of axial load and reduced ductility.
FRAGMENT DISTRIBUTION FROM AN ALUMINUM-CASED SHAPED CHARGE
During testing of a shaped charge that was intended as a third-stage self destruct mechanism, we gathered data on the fragmentation of an Al 6061-T6 case surrounding a shaped charge. Witness packs were placed around the charge in an arena-like configuration. These packs, comprised of Al 2024-T351 sheets and plywood, were placed 101 cm from the charge. Direct line-of-sight data was collected on two witness packs. A total of 161 fragments were recovered. The size and weight of each of these fragments was measured. The shapes of the fragments were analyzed as well as the fragment mass-cumulative mass distribution. These results are compared with fragmentation results with Al 2024-T351 where the fragmentation was caused by impact rather than explosive loading. The shaped charge-case fragments are more typically borderline in shape between flat and brick like, whereas the fragments from the hypervelocity impact (crater ejecta) are predominantly flat.
NUMERICAL AND EXPERIMENTAL STUDY OF EXPLOSIVE BLAST WAVES
This work focuses on the creation and propagation of blast waves and their interaction with objects, which is crucial for developing new explosives. To experimentally characterize these blast waves, the Fraunhofer ICT has enhanced its detonation chamber with a pressure lance that measures blast pressure over time at 1 meter from the explosive charge. Experimental findings are complemented by numerical simulations to identify explosive-specific parameters like the Miller term and to transfer the results to other scenarios. The Fraunhofer ICT utilizes various programs, including IMPETUS, SPEED, and OpenFOAM, for simulating blast waves. This work aims to evaluate the accuracy and usability of these programs by modeling the detonation chamber and simulating the experiment that is solved using different solvers. The results are then compared to the experimental results based on their accuracy and performance.
THE PARAMETRIC ANALYSIS OF FLOW CONTROL METHODS FOR FOREBODY SHOCK STRUCTURES IN SUPERSONIC FLOW FIELD
Hypersonic compressible flow fields subject vehicle leading edges to extreme aerodynamic heating due to high-temperature and high-pressure effects. This study focuses on a combined control strategy that integrates passive flow control structures (aerospike and aerodisk) with active flow control through jets to reduce aerodynamic heating and drag. Using numerical simulations with a two-dimensional axisymmetric model and the Reynolds-averaged Navier- Stokes equations combined with the SST turbulence model. The findings indicate that the aerodisk-lateral jet configuration transforms the oblique shock wave into a coherent structure, reducing reattachment shock intensity and enlarging the subsonic recirculation zone at the blunt body’s leading edge. Moreover, increasing the spike's length-to-diameter ratio and moving the aerodisk away from the blunt body further enhances cooling by expanding the recirculation zone and improving gas diffusion. The study concludes that the proposed strategy offers valuable insights for improving thermal protection systems and flow control devices in hypersonic environments, setting the stage for future research in this area.
HYPERSONIC, SUPPRESSOR-COMPATIBLE SMALL ARMS AND HYPERSONIC FLIGHT-SAFE AERIAL GUNNERY AMMUNITION
This paper starts with a brief overview of aerial gunnery evolution and USAF efforts to design discarding sabot ammunition from its inception until 1998 when it ceased advanced aerial gunnery RDT&E. In 2016 a new configuration was conceived, enabling novel flight-safe discarding sabot (FSDS) families of ammunition. These Ballistic Aeromechanically Stable Sabot (BASS) and Maneuvering Aeromechanically Stable Sabot (MASS) designs use monolithic sabots that clear airframes after firing by executing aeromechanically stable maneuvers. Everfaster variants of BASS and MASS rounds have methodically gained muzzle velocity, eventually reaching hypersonic speeds. The overall performance of these rounds are contrasted against the performance of conventional families of ammunition used in air-to-air and air-to-ground engagements for fixed- and rotary-wing aircraft. Special variants of BASS and MASS ammunition are also shown to be compatible with small-arms and mid-caliber suppressors through hypersonic muzzle velocities. The paper concludes with summaries of performance, IP landscape and new mission enablement.
RECENT DEVELOPMENTS AT THE SMDC AEROPHYSICS RESEARCH FACILITY (ARF)
The US Army Space and Missile Defense Command (SMDC) Technical Center (TC)’s Aerophysics Research Facility (ARF) recently reactivated its 133 millimeter (mm) and 254 mm Two-Stage Light Gas Guns (TSLGG) and developed a series of novel Single Stage Gas Gun (SSGG) systems for launching non symmetric projectiles. These latest developments enable the opportunity to build upon an extensive legacy of performing a wide range of ballistics research using the ARF’s suite of gas gun systems, diverse and adaptable test range infrastructure, extensive fabrication capabilities, and modern instrumentation and data acquisition equipment. These assets provide the ability to accelerate and study projectiles and flight dynamics at velocities ranging from subsonic up to hypersonic, within a secure government owned and supported, all weather facility. Recent and ongoing applications of these capabilities have focused on hypervelocity penetration mechanics, hypersonic dispersed phase interactions, and the effects of UAS impacts on commercial aircraft.
ANALYTICAL MODELING AND EXPERIMENTAL VALIDATION OF PRESSURE-TIME PROFILES IN MORTAR PRIMARY CARTRIDGES: IMPACTS ON PERFORMANCE OPTIMIZATION AND SAFETY
A comprehensive analytical model on the internal ballistics of a 60mm Mortar Primary Cartridge design is explored to simulate the burning of propellant inside the Primary Cartridge chamber. This analytical model is compared to experimental results to validate the accuracy and reliability of the proposed approach. The model effectively represents key internal ballistic phenomena, including transient pressure evolution, variations in combustion rate, and the influence of cartridge design, demonstrating strong agreement with experimental data. This provides detailed analysis of combustion dynamics, gas expansion, and propellant interactions. The comparison between the model and the experimental results provide actionable insight and better estimation of pressure vs time profile, leading to a better ignition of augmenting charges and safe operations.
BARREL EROSION ASSESSMENT FOR A 5.56x45 CALIBER WEAPON, IN LABORATORY AND OPERATIONAL WEAR REPLICATION SCENARIOS
Barrel erosion affects firearm performance, longevity, and reliability, necessitating precise measurement techniques for wear assessment. This study examines erosion in 5.56×45 mm calibre barrels under laboratory-controlled and operational wear replication conditions. A Ballistic Interchangeable Manometric Cannon (BIMC) and an FN SCAR barrel were analysed using Coordinate Measuring Machine (CMM) scanning and steel pin gauges to quantify material loss. CMM scanning provided high-resolution, micron-level accuracy, while pin gauges enabled rapid field assessments. Results indicate that erosion is most severe in the forcing cone due to thermo-chemical and mechanical degradation. Laboratory tests closely predicted operational wear trends, though real-world conditions introduced variability. These findings underscore the necessity of refining metrology techniques for predictive maintenance and service life estimation. Future research should focus on real-time monitoring advancements, enhanced measurement precision, and computational modeling for improved barrel wear assessments.
A METHODOLOGY TO SIMULATE INTERIOR AND INTERMEDIATE BALLISTICS WITH DYNAMIC MESH TECHNIQUE AND LUMPED PARAMETER CODE
The development of an interior ballistics (IB) lumped parameter code (LPC), integrating an original image processing method for calculating the regression of gun propellant grains is introduced. The ONERA CFD code CEDRE, equipped with a Dynamic Mesh Technique (DMT), is then used in conjunction with the developed LPC to build a dedicated methodology to calculate IB. The methodology is validated with the AGARD gun and 40 mm gun test cases. CEDRE is also used to calculate intermediate ballistics with a multispecies and reactive approach. The methodology developed in this work makes it possible to study the flame front of the muzzle flow and the depressurization that occurs in a base bleed (BB) channel at the gun muzzle.
ASSESSMENT OF A STRONG COUPLING APPROACH BETWEEN SOLID PROPELLANT COMBUSTION AND STRUCTURAL INTEGRITY OF A KINETIC ENERGY PROJECTILE
The in-bore transverse loads induced by the motion of the weapon and the inertial body forces induced by the motion of the propellant are often neglected when assessing the structural integrity of a kinetic energy projectile. It can be a drawback for APFSDS projectile with long rod penetrators. This issue may be overcome if the distribution of the main interior ballistic parameters (pressure and temperature) are correctly estimate in space and time. However, a realistic coupled simulation of the phenomena that take place within the interior ballistic cycle requires a great deal of effort and computerized resources. Two main methods are generally used: (i) the Euler-Euler method and (ii) the Euler-Lagrange method. In this paper, The *MAT_POWDER_BURN of IMPETUS AFEA is used to deal with the combustion of solid propellant. This method could lead to a strong coupling between the solid propellant combustion and the structural integrity of a projectile.1
DISCUSSION ON FULLY NON-EQUILIBRIUM TWO-PHASE FLOW MODEL FOR POSSIBLE APPLICATIONS IN INTERIOR BALLISTICS
The main task of interior ballistics is the modelling of the highly complex shot phenomenon, involving the combustion of propellant material and propulsion of the projectile. With the development of science, more detailed description of the ballistic cycle is possible. Many current models utilise two-phase flow models, with one phase being the unburnt propellant, the other – combustion gases, in one or more spatial dimensions. This allows to model the interior ballistic cycle in more detail. However, for interior ballistics simulations reduced models were developed, enforcing some equilibrium between phases. But with the development of numerical methods and increasing computing power of modern computers the more extensive seven-equation model could be utilized, which allows for full disequilibrium between phases. This model has useful features that could be utilized for more accurate interior ballistics simulations. Therefore, the aim of this paper is to analyse full nonequilibrium two-phase flow model and the numerical methods for solving such problems.
NUMERICAL STUDY OF THE IGNITION DYNAMIC OF A BASE BLEED UNIT DURING THE INTERIOR BALLISTICS PHASE
The aim of this article is to study numerically the ignition dynamic of a base-bleed (BB) unit during the internal ballistics (IB) phase. A Forward Facing Step case is studied under the physical conditions of the first instants of IB, in order to characterize the convective fluxes at the solid propellant surface of the BB. Large-Eddy Simulations are carried out with the CEDRE CFD code. The recirculation zone obtained in the flow significantly increases convective fluxes at the inlet of the BB channel. The instabilities generated by the recirculation zone have frequencies in line with literature. A second case is proposed to study BB ignition using a dynamic mesh technique and an unsteady solid propellant ignition model applied to the BB propellant surface. It can be shown that the propellant ignites quicker at the inlet of the BB channel due to higher convective fluxes, corresponding to the location of the recirculation zone.
NUMERICAL INVESTIGATIONS TO ESTABLISH CORRELATION BETWEEN BALLISTIC PROPERTIES EVALUATED FROM VARIOUS SAB-SCALE MOTORS
Evaluation of ballistic properties of solid rocket propellant is most critical activity for determining the performance of missiles or space vehicle. Among various available technique for evaluation of these properties, subscale motors are most accurate and reliable. Progressive and neutral sub scale motors (SSM) are mostly used for estimation of these properties. The paper proposes a methodology using numerical simulations for quantifying the impact of hump effect, tail off effect, dimension tolerances and instrumentation errors on the properties calculated from both the SSM. Simulated pressure time profile is numerically generated by varying burn rate, pressure index, throat diameter and grain geometry using an experimentally validated model. Effect of above mentioned parameters are incorporated in simulated profile using models reported in literature. A systematic analysis of these simulated data is conducted and limitations of progressive SSMs is established. The study brought the robustness of neutral BEMs for computation of ballistic properties.
AI BASED INTERIOR BALLISTICS MODEL FOR A 155 MM PILOTED GUIDED AMMUNITION, EXPERIMENTAL VALIDATION AND COMPLIANCE TO STANAG 4110
KATANA® is a 155 mm long-range, high-accuracy, precision-guided artillery projectile. Guiding ammunition requires controlling roll in flight at values much lower than those induced by the barrel rifling. A slipping band is a technical solution to meet this requirement but it results in leakages at the interface between the projectile and the barrel, making conventional interior ballistics models inaccurate. An interior ballistics model is important for several reasons during development and qualification but it is even more important for high added-value projectiles to reduce the number of rounds fired in order to establish compliance with standards such as AAS3P20 and STANAG 4110. A model based on machine learning using firing data was downselected. Experimental interior ballistics data are recorded on every firing occasion, using chamber pressure gauges and strain measurements along the barrel. This methodology is used to avoid formal SoPc firing and save projectiles.
THERMOCHEMICAL ANALYSIS AND FIELD PERFORMANCE OF SMALL ARMS PROPELLANTS FROM 1953 (30-06 M2 AP) AND 2012 (M55A1) AMMUNITION
When older stocks of ammunition are fielded for use, propellant degradation may alter chamber pressures, or in the worst-case scenario, may present risk for auto-ignition. Propellants harvested from U.S military cartridges—1953 30-06 M2 AP and 2012 M855A1 were evaluated using thermochemical techniques and field testing. Thermal analysis demonstrated similar energy densities between 1953, 2012, and 2022-era propellants with similar morphology. Minor changes in activation energy and stabilizer content suggested slightly decreased propellant thermal stability in the 1953 propellant. A novel application of modified thermogravimetric analysis (mTGA) is introduced and shows promise for more rapidly determining the properties of older stocks of ammunition being considered for use. In field testing, the 1953-era propellant demonstrated comparable standard deviations in velocity and on-target precision to the 2012 propellant, and both resulted in similar standard deviations in velocity and on-target performance to a modern extruded commercial reloading powder.
FACTORS AFFECTING BOLT THRUST AND EXTRACTION FORCES IN SMALL CALIBER WEAPON SYSTEMS
The brass cartridge case has been the standard for small caliber weapons systems since the late 1800’s. While brass has ideal material properties allowing for obturation during pressurization with enough elastic recovery for extraction, its high density makes its overall weight undesirable. In addition, next generation weapon systems are firing at pressures far higher than legacy systems, necessitating higher strength materials due to structural concerns. Previous work completed looked at the bolt thrust and extraction forces variations when the case material was varied between brass, high strength steel, and polymers. It was found that bolt thrust varied as much as 66% based off cartridge case material. It also showed that the use of Finite Element Analysis has good agreement with experimental results and could be used as a predictive tool. This report will examine additional factors within the weapon system affecting bolt thrust and extraction forces. Differences of friction coefficients and friction conditions within the chamber will be explored. In addition, weapon headspacing variations are considered. These will be coupled with the variations in materials previously studied to determine each material’s sensitivity to weapon conditions.
NUMERICAL MODELING OF WEAR IN INTERIOR BALLISTICS
When a barreled weapon is fired, the barrel will experience wear, which influences its lifetime. Repeated loading will further change the barrel geometry, leading to different side effects, such as pressure and velocity drop. In the presented work, mechanical wear is considered, and a wear criterion is proposed to be applied in finite element modeling. It considers the contact pressure and relative tangential velocity between the Faces in contact. This entity can be plotted as a contour plot or a wear profile as a function of the location along the barrel. Another entity is the wear volume, a way to quantify the wear with a single value. These wear entities and other options have been implemented into the used commercial explicit finite element code. A generic barrel is modeled to show the approach, and it is seen how a second run can take the worn barrel geometry into account. The software used for the simulations is the IMPETUS Afea Solver.
STUDY ON INFLUENCE OF MATCHING BETWEEN COMBUSTIBLE CARTRIDGE CASE AND GUN PROPELLANT BURNING RATE ON INTERNAL BALLISTIC PERFORMANCE
The matching between the combustible cartridge case (CCC) and gun propellant burning rate plays an important role in interior ballistic performance of charge since there is a large difference between their burning rate coefficients. This paper investigated the burning process and determined the burning rate coefficients of CCC and gun propellants using closed bomb test. The characteristic parameter, such as composition, thickness, and porosity of the CCC significantly affected the burning rate coefficient. The relationship between the burning rate coefficient of the CCC, maximum chamber pressure and muzzle velocity of 105mm tank gun propellant charge can be calculated through interior ballistic code. For a certain gun propellant, the expected interior ballistic performance can be obtained through a good match between the CCC and gun propellant burning rate coefficient. Compared to CCC with higher burning rate coefficient, the coefficient in the range of 5 to 6 mm·MPa⁻¹·s⁻¹ of CCC exhibits better matching property with 14/19 TEGDN gun propellants in 105mm gun firing and its suitable characteristic parameters are determined by an established model further. This study demonstrated the significance and strategy of match between CCC and gun propellant burning rate coefficient.
FDM—3D PRINTING OF THERMOPLASTIC COMPOSITES WITH HIGH ENERGETIC SOLIDS CONTENT DESIGNED FOR GUN PROPELLANTS
This study represents a significant advancement in the additive manufacturing of energetic materials, focusing on the 3D printing of gun propellants using Fused Deposition Modeling (FDM) technology. The primary goal of the study was to optimize the formulation, improve performance, and find a balance between printability and propellant effectiveness. Three different energetic formulations were tested as feedstock for FDM 3D printing, with only two proving suitable for the technique. The formulation consisting of 70% RDX, 10% NC, and 20% polycaprolactone (PCL) emerged as the most successful, offering excellent processability, ease of printing, and superior energetic performance. This formulation stands out as the most promising for the production of gun propellants through FDM 3D printing. The article is included in Defense Technology special issue "VSI: 34th International Symp Ballistics"
SIMULATION OF THE INFLUENCE OF MULTI-MATERIAL AND COMPLEX-SHAPED PROPELLANT COMBUSTION IN A 120 MM TANK GUN
In the development process of ammunition, grain design plays a crucial role in controlling pressure evolution in the system and thus the performance of the ammunition. Additive manufacturing techniques offer novel opportunities for geometric shapes and material structures of propellant grains due to the large number of degrees of freedom. To quantitatively assess the potential, this work presents an approach in which the packing density is simulated, considering the real system. Using the resulting propellant mass, pressure evolution in the weapon system is computed according to the STANAG 4367. Applied to a generic 120 mm tank cannon L50, 7pf sphero-cylinders with different spherical cap heights were investigated and compared with a 7pf cylinder. It is demonstrated that these geometries can increase muzzle velocity by up to 9 %.
A NOVEL APPROACH OF THE IGNITION AND COMBUSTION SIMULATION OF DEM-BASED THREE-DIMENSIONAL PROPELLANT BEDS IN CASED MUNITIONS BASED ON AN EXTENDED DISCONTINUOUS GALERKIN METHOD
A comprehensive understanding of the internal ballistic processes during ignition and combustion is essential. This research emphasizes the need for detailed simulations of the three-dimensional propellant bed, considering specific grain geometries and the design of igniters that affect fluid flow within the combustion chamber. Current numerical models often cut down these processes, leading to a simplified representation of local ignition phenomena. To address this, an extended ignition and combustion model for statistical three-dimensional propellant beds is proposed, utilizing an extended discontinuous Galerkin method (XDG) to account for complex interactions between solid and gaseous phases. The study aims to improve the accuracy of predictions related to local ignition and combustion phenomena, which is vital for the development of safer and more efficient ammunition systems, while also outlining the mathematical framework and computational methods used for this purpose.
ANALYSIS OF PRESSURE WAVES IN GUN BARRELS USING A MESHLESS METHOD
In this study, the projectile motion in the interior ballistic regime is numerically simulated using a moving grid axisymmetric second-order Euler Finite Volume solver. A gridless method involving moving discrete points is validated against the experimental results of an M107, Zone 5 shell fired through an M198 cannon. The algorithm for solving Arbitrary Lagrangian-Eulerian (ALE) equations based on clouds of points in the computational domain is used. The Harten, Lax, van Leer, Contact (HLLC) scheme extended into the gridless method is used to calculate the numerical fluxes along with Van-Leer limiter for avoiding spurious oscillations. The muzzle velocity and peak pressures computed by the Gridless solver are in good agreement with the experimental results. Further, the current solver is used to study the effect of SSP and shell mass variations on the flow dynamics and pressure rate change in the combustion chamber.
OPTIMIZING PROJECTILE DESIGN IN ARTILLERY SYSTEMS: THE ROLE OF BLOW-BY IN GUN PERFORMANCE & TUBE WEAR
This study examines the impacts of blow-by phenomena in 155mm projectiles and the effectiveness of obturators on sealing gun tube pressures. Six tests were conducted at Yuma Proving Ground (YPG) using a 155mm projectile with only minor configuration changes of driving band systems. Four rounds were fired out of a fourth quartile wear gun tube. Two were equipped with obturators and two were not. The last two projectiles were fired with obturators in a first quartile gun tube. These tests were conducted in a howitzer with a 39- caliber barrel at a top zone charge. The research quantifies pressure distribution variations within the gun tube and analyzes asymmetrical blow-by pressure patterns under different firing conditions. Results demonstrate that obturators significantly reduce blow-by pressures, by as much as 93.5%, and gun tubes with less wear on them exhibit lower blow-by. Pressure measurements revealed distinct asymmetrical patterns, critical to understanding the way that the gun tube wears. These findings provide valuable insights for projectile design optimization and performance enhancement in large-caliber artillery systems.
NUMERICAL SIMULATION ASSESSMENT OF EROSIVE BURNING IN SOLID PROPELLANT ROCKET ENGINES
Erosive burning is a critical phenomenon affecting the performance and reliability of rocket motors, particularly those utilizing solid propellants. In erosive burning, the combustion rate of solid propellants increases due to high-velocity gas flow along the propellant surface. This occurs predominantly in motors with narrow or complex grain geometries, where the increased shear stress and enhanced heat transfer from the gas flow accelerates the burn rate beyond what is expected in static conditions. This paper aims to evaluate the influence of erosive phenomena that occur in the rocket motor, in the case of a narrow port grain solid propellant, using numerical simulation as a means of investigation. Starting from a given configuration, the operation cycle of the solid-fuel rocket motor is simulated, beginning with the ignition phase and continuing until the complete combustion of the propellant. The simulation is conducted in two cases, without and with considering the effect of erosion. This allows for the obtaining the pressure, temperature, velocity fields and variation of pressure at the nozzle inlet, which are compared in both cases. Additionally, comparisons with experimental results obtained for the same configuration are made. The numerical simulation is performed using the FLUENT program, with input data obtained through thermochemical calculations.
STRESS ANALYSIS OF GUN BREECH BLOCK FOR GUN DESIGN APPLICATIONS
This study presents a detailed Finite Element Analysis (FEA) of a breech block featuring a buttress thread, aimed at understanding the stress distribution under various loading conditions. Buttress threads, known for their high load-bearing capacity and asymmetrical profile, are commonly used in applications where high axial loads are required, such as in hydraulic systems and fasteners. Utilizing Abaqus, a comprehensive stress analysis was conducted on the threaded block to assess critical factors such as stress concentration, deformation patterns, and the overall integrity of the design under different loading scenarios. The model was created using precise geometric definitions of the buttress thread, including the lead angle and asymmetric thread profiles. The material properties were assigned based on realistic parameters commonly used in industrial applications, this material was steel 4340. Static loading conditions were applied to simulate operational stresses, and a fine mesh was employed to capture the detailed stress distribution around the thread roots and flanks, where stress concentrations are typically highest. The results revealed that the buttress thread design effectively distributes axial loads along the inclined surface, minimizing stress concentrations compared to conventional thread forms. This design of the breech block based on the buttress thread is extremely important when it comes to the gun design and it is a good reason why the buttress thread is design in this way for most guns. However, significant stress concentration was observed at the root of the thread, necessitating potential design optimizations. This analysis demonstrates the efficacy of buttress threads for highload applications in gun designs, with the FEA results providing valuable insights for further refinement of the design. The study validates the use of Abaqus in performing detailed stress analysis of complex geometries, showcasing its capability to predict critical stress regions and potential failure points. Recommendations for future work include fatigue analysis and exploring the effects of varying thread dimensions on stress distribution to judge the novelty in our work.
STREAMLINING THE DESIGN OF NEUTRAL BURNING SOLID ROCKET MOTORS: A GUI-DRIVEN COMPUTATIONAL APPROACH
This paper presents a computational tool for optimizing SRM internal ballistics, focusing on neutral burning star grain geometries. Users input mission-specific parameters such as thrust, burn time, and grain caliber, along with chamber pressure ranges, select propellants, and predefine geometric constraints on the star. The tool employs two 0D flow models for efficient simulations, enabling rapid iteration and optimization. Validation of the analytical burn-back model showed strong agreement with the Level Set Method (LSM), with an average deviation of 0.35% in web thickness and 0.959% in burning area predictions. A case study demonstrated its capability by evaluating 103,289 unique star grain designs, selecting optimal configurations with thrust variations under 0.02% and burn time deviations within 0.04%.The tool is integrated into a graphical user interface (GUI), streamlining design with minimal programming knowledge. This approach enhances accuracy, reduces trial-and-error, and ensures robust SRM designs for mission-specific applications.
SCREENING OF METAL ADDITIVES IN ABS POLYMER FUEL FOR ENHANCED PERFORMANCE IN HYBRID ROCKET MOTORS: A COMPUTATIONAL ANALYSIS USING CEA
This study explores the use of metal additives in acrylonitrile butadiene styrene (ABS) polymer fuel to enhance hybrid rocket motor (HRM) performance through computational analysis using Chemical Equilibrium with Applications (CEA) software. ABS was chosen for its thermoplastic properties, enabling complex 3D-printed fuel designs. Hybrid rockets combine solid fuel with liquid oxidizers, offering operational simplicity and safety, but conventional polymer fuels often have low regression rates and combustion efficiencies. We tested various metal additives—aluminium (Al), boron (B), nickel (Ni), copper (Cu), and iron (Fe)—across 1,800 unique conditions at chamber pressures of 1 to 30 bar and oxidizer-to-fuel ratios between 1.1 and 12. Results of the characteristic velocity (C*) indicated that Al and B significantly improved combustion performance, while Fe, Cu, and Ni reached optimal performance at a minimum loading of 1% with no further improvements. Future work will focus on B-Al composites and experimental validation of metallized ABS fuel. This extended abstract is based on a full paper to be published in the Defence Technology Journal.
EFFECT OF TEMPERATURE, CONTENT OF PLASTICIZER AND NITROGEN CONTENT OF NITROCELLULOSE ON THE IMPACT SENSITIVITY OF GUN PROPELLANTS
The development of modern gun weapons requires high energy, low sensitivity and wide temperature range gun propellants. In order to improve the formulation of gun propellant, the effects of initial temperature of gun propellants, content of energetic plasticizers and nitrogen content of nitrocellulose on the impact sensitivity of gun propellants was evaluated comprehensively. The results indicate that with the increase of initial temperature, the impact sensitivity of gun propellants increased. When the temperature rises to 80°C, in 25 parallel tests of two gun propellants, the explosion probabilities increased from 5/25 and 2/25 to 24/25, respectively. When the nitroglycerin (NG) content was increased from 30% to 50%, the drop hammer height at which the explosion probability reached 50% (H50) decreased from 14.96 cm to 4.49 cm. When the content of diethyleneglycol dinitrate (DEGDN) increased from 30% to 40%, the H50 value of the gun propellants decreases from 5.21 cm to 3.49 cm. When the nitrogen content of nitrocellulose increases from 12.0% to 13.5%, the impact sensitivity of the gun propellants increases significantly. Overall, this study might provide theoretical basis and data support for the design of gun propellant formulations.
ENHANCED 155 MM ARTILLERY PROPELLING CHARGE DEVELOPMENT WITH NUMERICAL MODELLING AND A DEEP-LEARNING APPROACH
Since the start of the war in Ukraine, one can realize the emphasis put on long-range artillery fires. Based on this observation, the EURENCO Group is developing new artillery propelling charges with improved interior ballistics performances and range. Developing and testings these charges may present a certain level of uncertainty because the dynamic behaviors of a new propellant and charge is difficult to accurately predict from closed vessel experiments and 0D numerical calculations. EURENCO is building models to tackle these issues in particular using a deep-learning based surrogate model coupled with EURENCO proprietary 0D internal ballistics numerical modelling code in order to increase numerical calculations representativeness. These modelling codes were used to support a long-range propelling charge development process. They allowed to determine optimal propellant grain dimensions and the velocities (deep-learning based model) and pressures (0D model) were fairly well predicted. Thus, development time and safety management were greatly improved.
OPTIMUM EPOXY RESIN-BASED COATINGS TO IMPROVE THE PROTECTION OF COMBUSTIBLE CARTRIDGE CASES
In this study, an epoxy resin-based coating (ERBC) was synthesized via an optimum coating formula, significantly improving the environmental adaptability of CCCs. Finally, the effects of diluent content on the curing time and the heat resistance of composite coatings were analyzed in detail. It was found that the increase in diluent percentages could effectively promote the fluidity and spraying effect of the coatings, while simultaneously decreasing the overall salt corrosion resistance and hightemperature resistance. It was further determined that the optimized diluent percentage of 7.5 wt% could resist a temperature of 240 °C for 105 s with high environmental adaptability. This study is of significance for future research on the protection and practical application of CCCs, with an expanding scope in the field of weapon ammunition.
ENHANCING ACCURACY IN BURNOUT TIME ESTIMATES IN BURN RATE EVALUATION OF SOLID PROPELLANT BY FIRST DERIVATIVE APPROACH
Burn rate of solid propellant is an important ballistic parameter for performance evaluation of Solid Rocket Motors. Normally burn rate is evaluated by testing of small-scale solid rocket motor with neutral pressuretime profile at designated test pressure. Method adopted the most widely used tangent bisection method uses ratio of web-to-web burnout time to determining burn rate. Accurate determination of burnout time occupies an obvious importance. In the present methods, burnout time is estimated by drawing a tangent at the peak of the Pressure-Time (P-t) curve at aft end. This approach poses limitations when applied to P-t curves exhibiting nonlinear post-burnout pressure decay or varying slopes. Such conditions often result in misaligned tangents, leading to erroneous burnout time estimates and consequently inaccurate burn rate estimations. This paper introduces the first derivative method as a more robust alternative for determining burnout time for neutral and nearly neutral pressure time profile. In-house application has been developed for automatic burn rate estimation using the first derivative method. The method has been validated with large numbers of Ballistic Evaluation Motor (BEM) tests with test pressures ranging from 3.3 MPa to 7 MPa. The first derivative method offers a significant improvement over traditional techniques, providing more reliable burn rate estimations, enhancing burn rate accuracy.
STUDY ON DAMAGE MECHANISM OF PROJECTILE ENGRAVING INTO DIFFERENT RIFLED BARREL PROCESSES
A physical calculation model of rifled barrels with diverse section forms was constructed to investigate the damage mechanisms of projectiles engraved into various rifled barrels. In addition to simulating the dynamic process of projectiles engraving into rifled barrels using the finite element approach, the engagement force and radial strain of various rifled barrels were compared experimentally. Both the dynamic reaction of the projectile engagement force and the damage cloud map of the projectile are provided. According to the computational results, the barrel with a circular rifled shape had the lowest engagement force and least equivalent plastic strain-based damage, which makes it appropriate for use in engineering applications. These computed results agree well with the experimental results.
STRESS INTENSITY EVALUATION AND ANALYSIS OF PISTON-TYPE SILENCED CARTRIDGE CASES
To investigate the method of stress intensity evaluation for piston-type silenced cartridges, the container check method was employed to conduct a strength analysis. By examining the force characteristics on the inner wall of the piston cartridge case and combining it with the properties of the chamber pressure curve, the dynamic load coefficient was derived. The inner wall of the cartridge case was sectioned based on force regions, with different loads applied to each section for numerical calculations. This provided results for equivalent stress, deformation, etc. These results were analyzed through stress and deformation contour maps and contact states, and compared with numerical results where the inner wall directly bears maximum chamber pressure. The analysis concludes that partitioning the load-bearing regions of the inner wall of a piston-type cartridge case more effectively reflects actual conditions. In evaluating the stress results for three materials— 45# steel, GCr15, and 40Cr—it was concluded that 40Cr exhibits superior performance in the strength analysis of piston-type cartridge cases.
ANALYSIS OF RELATIONSHIP BETWEEN STATIC AND DYNAMIC ENGRAVING RESISTANCE OF BULLETS
This study investigates the relationship between quasi-static and dynamic engraving resistance of bullets. A 12.7 mm solid copper bullet was tested using a custom-designed quasi-static engraving experimental setup, and an interaction model between the bullet and barrel was established. Dynamic engraving resistance was derived by combining dynamic testing with numerical simulations. The results reveal that the peak quasi-static resistance occurs earlier than the dynamic peak, and the number of resistance peaks is independent of the cylindrical structure. The study demonstrates that quasi-static resistance can effectively predict dynamic engraving resistance for solid copper bullets.
STUDY OF DEPENDENCE OF BURN RATE PARAMETERS OF GUN PROPELLANT ON PRESSURE AND ITS EFFECT ON PERFORMANCE PREDICTION
Tank gun performance prediction is highly sensitive to the ballistic properties of propellants, particularly how their burn rates respond to changing pressures. Traditional models assume static burn rate parameters, but modern nitramine-based propellants exhibit dynamic combustion behaviour. This study investigates the pressure dependence of burn rate parameters, pressure exponent (α) and burn rate coefficient (β), using closed vessel experiments at loading densities of 0.2, 0.3, and 0.4 g/cc for a nitramine-based propellant. Results reveal that both the parameters evolve dynamically with respect to pressure. A novel pressure-dependent burn rate model, a modified Vieille Law (r = β(P).P^α(P)), is constructed and integrated into a Lumped Parameter Model (LPM) for Internal Ballistics prediction. Application of this model in 120mm tank gun Internal Ballistic simulations has reduced the error range in muzzle velocity (MV) prediction from 2.88%-4.32% to 0.14%-1.14% and reduced the error range in maximum chamber pressure (Pmax) prediction from 32.43%-62.43% to 0.60%-6.63%. These advancements enhance safety by mitigating catastrophic pressure spikes and improve precision for military applications.
COUPLED FLUID-STRUCTURE CALCULATIONS TO PREDICT THE ROLL INDUCED BY FLEXIBLE FINS ON 155 MM PILOTED GUIDED AMMUNITION
KATANA® is a 155 mm long-range, high-accuracy, precision-guided artillery projectile. Guiding ammunition requires controlling roll in flight. To achieve this, the geometry of the fins in flight is an essential factor but is mainly the result of several loads occurring successively from the manufacturing stage to the interior, intermediate and exterior ballistics phases. Modeling was carried out for all these stages, including coupled fluid-structure interaction and the effect on induced roll was assessed. This model provides a better understanding of each physical phenomenon, their impact on the final geometry of the fin and the consequences on flight. It enables quicker and more efficient analysis of incidents, optimization of design and prediction of performances. Experimental trajectories were modeled, considering measured data as projectile mass and measured muzzle velocity of each round, and compared with firing radar and telemetry records. Each stage of the modeling and validation is explained and illustrated.
NUMERICAL MODELLING OF THE TEMPERATURE DISTRIBUTION IN A 155 MM ARTILLERY BARREL DURING OPERATIONAL RATE OF FIRE
The rate of fire of a 155 mm artillery gun is one of the more strategic parameters to achieve the superiority on the battlefield. However, significant safety risks may arise due to the overheating weapon such as propellant cook-off or projectile exudation. Depending on the number of rounds fired, during a sequence, the chamber surface temperature could reach an undesirable condition known as the cook-off temperature of the propellant resulting in its premature and unintended ignition in the barrel. Using a detailed interior ballistic calculation as input parameters, the heat flux is derived from different hot gas friction model for various firing sequences. The thermal problem is then solved using COMSOL Multiphysics with a PARADISO time-dependent solver and the results obtained for the different heat transfer model are compared for various axial position. This preliminary work is a first step towards the development of a comprehensive model. The results demonstrate the ability of the model to accurately predict temperature distribution within the barrel and aim for validation against high cadence firing scenarios. Furthermore, this thermal model is easily transposable to other medium or large caliber guns.
QP-BASED OPTIMAL DESIGN OF RIFLING TWIST TO REDUCE RIFLING FORCE
Rifled barrels, which are widely employed to impart spin stability to projectiles, are prone to accelerated wear due to the concentration of rifling forces. This study introduces an optimization framework for the rifling twist angle, formulated based on a linearized riflingforce model, to address this issue. By discretizing the barrel length and representing design variables within a state-space framework, the proposed method utilizes quadratic programming to minimize peak rifling forces under predefined in-bore pressure and projectile velocity conditions. The findings indicate that the optimized twist-angle profile effectively mitigates rifling-induced stresses, thereby enhancing the potential service life of the barrel. Moreover, the method’s adaptability to diverse design constraints further underscores its practical applicability in advanced barrel design.
EFFECTS OF AIR JET AND MIST INJECTION ON THE COOLING PERFORMANCE OF THE INNER SURFACE OF A GUN BARREL
During firing, a significant amount of heat is transferred to the inner surface of the gun barrel, leading to wear and erosion. With prolonged firing, the temperature inside the chamber can reach the cook-off point of the propellant, creating safety hazards for both the operator and the equipment. For large-caliber guns, such as the 52-caliber type, the use of high-energy propellants combined with increased firing rates greatly restricts the weapon's operational capacity. A practical approach to addressing this problem is the implementation of cooling techniques for the barrel. In this study, air and mist cooling methods are applied, and the heat transfer within a 155 mm gun barrel is analyzed through numerical simulations. Numerical simulations were conducted using the commercial computational fluid dynamics software, ANSYS Fluent. For comparison purposes, heat transfer in a naturally cooled barrel was also analyzed as a baseline case. The findings indicate that air and mist cooling are significantly more effective than natural air cooling in dissipating heat from the barrel, primarily due to the higher convection heat transfer coefficient. Air is often readily available and cost-effective. The impingement of a low-temperature air jet on the inner surface of the barrel improves cooling performance. Jet impingement cooling efficiency is influenced by various factors, such as jet diameter, injection velocity, and the distance between the jet and the heated surface. Water's latent heat of vaporization is 2260 J/g, and this property enables mist cooling to offer exceptional heat removal efficiency. This high energy absorption during phase change enhances the cooling performance significantly. ANSYS Fluent supports multiphase modeling through the Eulerian-Lagrangian approach, commonly referred to as the Discrete Phase Model (DPM). For research on mist cooling, the Discrete Phase Model (DPM) was utilized to simulate the behavior of injected mist particles. Mist cooling efficiency is influenced by various factors such as the size of the mist droplets, the velocity of injection, and the temperature of the mist. The numerical findings indicated that the inner surface of the gun barrel experienced a temperature reduction of approximately 5.8°C due to air jet impingement cooling as seen in Figure 1, while mist injection cooling led to a more significant reduction of around 12.2°C as shown in Figure 2. In contrast, natural air cooling only resulted in a temperature drop of about 2°C over the same period. These results demonstrate the high effectiveness of mist cooling as a cooling method.1
CALCULATION METHODS FOR DIFFERENT TYPES OF PROPULSIONS SYSTEMS FOR DISPOSABLE GRENADE LAUNCHERS
The paper shows calculations methods of disposable grenade launchers for infantry or airborne forces. The main goal of these calculations is determining of parameters ensuring recoilless and proper velocity of projectile according to requirements. The paper consists of calculation methods for four common types of recoilless propulsion systems: witch rocket solid fuel engine, recoilless systems with a simple launcher tube with an open rear part of the tube or with a launcher with a nozzle compensating of recoil and system with counter-mass. Another crucial aim of the calculations is determining the strength of critical elements, which allows checking up safety of a weapon during its development process.
EVALUATION OF WEAPON DYNAMICS AND WEAPON MOUNT DYNAMIC RESPONSE
Evaluating the dynamic response of weapon systems is challenging. Measurements, typically estimated using accelerometers or laser-based sensors, require adequate full-scale and dynamic ranges to avoid errors. Weapon firings involve short-duration shock loads, where displacements and velocities, rather than accelerations, are of primary interest. Numerical integration of acceleration data can be inaccurate due to signal frequency response, integration strategy, and initial conditions. Placement constraints, such as thermal issues or cabling inaccessibility, further complicate sensor use, often requiring multiple accelerometers. To address these challenges, Flamengro has developed a Computer Vision (CV) algorithm to track full-field displacements using image markers. The algorithm determines marker positions and calculates displacements, while velocities and accelerations are obtained via numerical differentiation, eliminating integration risks and sensor placement limitations.
GUN BARREL VIBRATION AND EFFECT ON ACCURACY
In modern warfare, targets must be engaged quickly with a minimum expenditure of ammunition and barrel wear. In many cases, the barrel is in a state of vibration. It may not be pointed at the target when the projectile emerges. The projectile is released obliquely to the muzzle flow and is unstable. We analyze the vibration and calculate its effect on the trajectory.
SUPPRESSOR PERFORMANCE ASSESSMENT METHODOLOGY
To execute effective design and development of suppressors, objective metrics are needed to assess performance. Test measurements from a set of commercial models and prototype configurations were reviewed to determine the role of peak pressure and impulse. The relationship between these metrics and the response of the ear, as measured with the DoD’s Auditory Risk Units, is investigated. It is found that the actual pattern of the pressure is key, and the ear response is driven by the low frequency aspects of the signature. The findings suggest metrics useful in assessing designs during the development process.
ANALYSIS AND NUMERICAL CALCULATION OF THE CAUSE OF ACCIDENTAL FAILURE OF A FIREARM WITHOUT EJECTION AT LOW TEMPERATURE
Failure of firearms without cashing significantly affects their performance and reliability. This study conducted an in-depth investigation of this key issue. In this study, a comprehensive analysis of the failure and ammunition structural parameters, such as the shell material, mechanical properties, surface treatment, and gun structural design parameters, including the barrel bore structure, roughness, unlocking stiffness, unlocking time, pre-ejection mechanism, and gas system structural parameters, was conducted. Through the use of theoretical formula for rigorous theoretical analysis, and with the help of Abaqus finite element numerical simulation software, the barrel and shell under the pressure of the chamber of the radial deformation of the accurate calculation, then carefully analyzed and compared with the actual measured value. The results show that many parameters of ammunition and firearms have a significant impact on the extraction process, and an unreasonable design of the chamber size, shell wall thickness, or machining error will lead to non-extraction failure. In addition, the actual shooting test revealed that the full combustion of porous powder in a low-temperature environment leads to an increase in the chamber pressure, plastic deformation of the shell case, and an increase in the resistance to the chamber, which leads to the occasional failure of non-ejection.
DYNAMICS SIMULATION OF AUTOMATIC WEAPON MECHANISMS AND THEIR IMPACT ON SHOOTING ACCURACY
This study investigates the dynamics simulation of automatic weapon mechanisms and their impact on shooting accuracy. First, a three-dimensional solid model of the automatic mechanism was established using UG software and imported into ADAMS to construct a virtual prototype. By applying various constraints, loads, and kinematic relationships, a virtual prototype model consistent with the actual system was developed. Subsequently, the gas chamber force was determined and applied to the piston in ADAMS via spline-type data. Finally, simulations were conducted to analyze the influence of different automatic mechanism parameters on barrel deflection angles, thereby evaluating their impact on shooting accuracy. The results demonstrate that factors such as bolt mass, bolt carrier mass, and recoil spring stiffness significantly affect shooting accuracy within specific ranges.
AN EXPERIMENT METHOD FOR VERIFYING THE STRUCTURAL STRENGTH SIMULATION OF FIREARM PARTS BASED ON OPTICAL MEASUREMENT
In order to explore the simulation test verification method for firearm parts structural strength, this paper take the locking strength of the certain firearm parts—the head stock body as the research object, adopts the optical measurement method, design the test scheme. At the same time, based on finite element simulation software, establishes the corresponding strength simulation model of the firearm part, and verifies the simulation calculation results based on the test results. Through the tests, the bolt head under the static pressure of 300 MPa, produces a strain of -3100μεto-3700με, and the simulation result at the same position is-3200με. The simulation calculation results are within the range of the test results. Through simulation, the accuracy of the simulation test results is verified. The research results show that the optical measurement method can overcome the influence of the size of the test piece and accurately measure the strain of the part. At the same time, the results of this study also provide a test method for the verification of the structural strength simulation results of firearm parts.
COMPARISON BETWEEN INTERNATIONAL STANDARDS UTILIZED FOR TESTING BALLISTIC HELMET PERFORMANCE
Many existing ballistic helmets are able to withstand ballistic threats, however, the residual energy of projectiles is still too high, which leads to back-face deformation and life injuries due to loads transmitted through the helmet to the head. VPAM HVN 2009 test standard considers residual energy transferred to the head by measuring the volume of the dent formed in the head where energy transmitted to the head shall not exceed 25 joules. NIJ 0106.01 test standard considers impact transferred to the head where peak linear acceleration energy transmitted to the head shall not exceed 400 g. The aim of this study was to investigate the relation between VPAM residual energy test and NIJ impact attenuation test through experimenting ballistic helmets from the same type and size. Test results showed that an increase in the projectile velocity leads to a significant rise in the values of impact attenuation due to the increasing in the bullet energy. However, the increase in residual stress was found to be minimal. This suggests that while higher projectile velocities influence the dynamic performance of the helmet in terms of impact absorption, they have a relatively small effect on the internal stresses that remain in the material after impact. This could be due to the specific design or material properties of the helmet, which might allow for better distribution of the stresses during impact. These findings highlight the importance of considering both impact attenuation and residual stress in evaluating the performance of ballistic helmets under varying conditions.1
COMPONENT KILL CRITERIA ESTIMATE FOR A SMALL COMBUSTION ENGINE—EXPERIMENTAL PART
Vulnerability and lethality (V/L) assessments can provide probabilities of a successful engagement or probabilities of kill given hit. The assessments require information about the munition, target and engagement conditions. The targets used in V/L assessment software are normally described on a component level in combination with ballistic protection performance and definitions of primary functions of the target (e.g. mobility, fire power). In order to evaluate if a target function or capability is lost after an engagement, it is necessary to determine the status of all the components that contribute to that specific function. The component kill criteria relates the damaging load on the component to a probability of rendering the component non-functional. The functional status of the complete target can then be derived from the status of each individual component by a fault tree analysis. This paper presents the experimental part of a work aiming to strengthen the process of defining component kill criteria. Projectiles were fired against running lawn mower engines. The engines were later disassembled in order to study the internal damage. The results generated here will be used in a following simulation based study aiming to find a kill criterion.
ENCLOSED BLAST RESPONSE OF PRE-DAMAGED COMPOSITE PLATES IN BARREL EXPERIMENTS
This study investigates the blast response of carbon fiber-reinforced polymers (CRFRP) in a closed barrel experiment. The plates are mounted on the side of a cylindrical barrel in which a spherical charge is fused. Both undamaged and plates with drilled holes are studied. Comparisons are made with results from a previous study using the same experimental setup for thin steel plates of equivalent surface weight. It is found that the undamaged carbon fiber plates can withstand blast from high explosive charges of 130 g, significantly higher than the 105 g sufficient for steel plates to fail. Introducing drilled holes into the plates, the CFRP plates failed for 110g of high explosive relative to 60g sufficient to rupture the steel plates.
ANTICIPATED IMPACT OF STRUCTURAL REACTIVE MATERIALS ON A WARHEADS IM
Structural reactive materials have been identified as feasible technology to improve a warhead’s lethality by air blast/bubble energy, behind armor effects, or as small sized initiation elements. Laboratory scale sensitivity test data reveal that many SRM formulations show a much higher shock and thermal insensitivity level compared to the well-known energetic materials TNT and HMX. Even though few data were identified in literature, estimation of IM test results is possible by generic reaction models. Based on the NATO AOP-39 framework, the IM characteristics of non-mitigated SRM warheads are anticipated to be between Type I (SR/SJ) and Type III (FH/SH/BI/FI), which is significantly worse than the current state of the art (i.e. Type IV – VI). With IM SRM compositions and applied venting and shock mitigation, response levels of Type III for SR and SJ tests seem achievable and even better results of Type IV-V for FH/SH/BI/FI.
HYDRODYNAMIC RAM IN FIGHTER JET AIRCRAFT FUEL TANKS: INVESTIGATION OF THE IMPACT OF TANK DEPTHS
When a high-velocity projectile strikes a fluid-filled closed volume, it transfers its kinetic energy to the fluid, causing deformation to the surrounding walls, this phenomenon is known as hydrodynamic ram. This is a key concern in fuel tank design for both commercial and military aircraft. Hydrodynamic ram is crucial for vulnerability studies, particularly in fighter jet design, to determine failure points under impact. Numerical modeling with LS-DYNA’s ALE tool used in this study enables fluid-structure interaction simulations. Additionally, tank depth and filling levels influence hydrodynamic ram damage. To the best of our knowledge, the direct impact of fuel tank depth has not been thoroughly analyzed. This study compares two generic fuel tanks with identical dimensions except for depth, tested at different filling levels. Results indicate that shallower, more filled tanks are more vulnerable to hydrodynamic ram damage.
IMPROVED ASSESSMENT OF AMMUNITION EFFECTIVENESS USING HIGH-DEFINITION DESCRIPTIVE FRAGMENTS SPRAYS MODELS
This paper deals with the weapon model as input data for vulnerability/lethality simulation. Such simulations are widely used in military equipment acquisition programs. These models are employed in lethality and vulnerability codes to assess the interaction of weapon effects with targets. The work presented in this document aims to achieve a more realistic description of weapon effects in V/L codes, especially for fragments velocities issues.
ASSESSMENT OF SKIN PENETRATION SURROGATES FOR USE WITH LESS LETHAL IMPACT MUNITIONS
Less lethal impact munitions (LLIM) are often used by law enforcement as a less harmful deterrent, yet severe injuries due to the LLIM penetrating the skin have been reported. As penetration thresholds vary with anatomical differences, a biofidelic skin penetration surrogate is essential for end users to perform pre-deployment risk assessments. This study evaluated three skin penetration surrogates—TrueTissue, TP5, and NATO AEP-94—using two spherical rubber projectiles. Penetration risk curves were produced with velocity and energy density. Risk curves yielded 50% penetration thresholds of 16.2, 16.9, and 16.0 J/cm2 for TrueTissue, TP5, and NATO AEP-94 respectively, aligning with post mortem human specimen thresholds for the thigh (12.6 J/cm2) and abdomen (18.7 J/cm2) (Foley, 2024). Despite differences in materials and design, all surrogates produced comparable responses within 1 J/cm2 of each other suggesting similar responses. This information can be utilized to help assess the risk of penetration for LLIMs.
DEVELOPMENT OF A BIOMECHANICAL FINITE ELEMENT ANALYSIS (FEA) MODEL USING OPEN-SOURCE SOFTWARE FEBio
This study develops a Finite Element Analysis (FEA) model of the human ankle using FEBio to simulate biomechanical responses under under-body blast (UBB) conditions. FEBio’s advanced capabilities enable accurate modeling of soft tissue mechanics, bone structures, and non-linear material properties. The model incorporates detailed anatomical structures and material properties from literature and experiments to capture interactions between bones, cartilage, and ligaments. Simulations under UBB conditions assess axial stress and contact forces, identifying high-risk injury zones. Results show stress concentrations at the upper tibia during vehicle acceleration and at the calcaneus upon ground impact, aligning with clinical injury data. Future work will focus on experimental validation and refining material properties. Insights from this study will inform protective strategies to reduce lower limb injuries. This research advances understanding of injury mechanisms and stress distribution, contributing to military safety and biomechanical applications in injury prevention. This summary contains 142 words.
STUDY ON THE VELOCITY DISTRIBUTION OF BEHIND-ARMOR DEBRIS FROM ROD PROJECTILE OBLIQUELY PENETRATING INTO RHA PLATE
To thoroughly analyze the velocity distribution characteristics of behind-armor debris (BAD) generated by a rod projectile during oblique penetration of a rolled homogeneous armor (RHA) plate, an experiment was conducted using a 220 mm thick RHA plate. Positional and mass data for the BAD were collected. Combined target experiments revealed the velocity attenuation patterns of tungsten and steel debris under specific target configurations. By back-calculating the velocity of the BAD, the velocity distribution characteristics of the debris in different scattering angle ranges were observed, and a descriptive equation for the velocity distribution of the BAD was fitted.
ASSESSMENT METHODS FOR DAMAGE TO HYPERSONIC TARGETS UNDER THE EFFECT OF BLAST-FRAGMENTATION AMMUNITION
ELEMENT FOR INCREASING ERA SANDWICH EFFECTIVENESS
Sandwich elements of Explosive reactive armours are used for a long time as a protection against shaped charge warheads. This paper presents an element that considerably reduces residual penetration in different attack angles. The paper includes basic research and development as well as numerical simulations. This element, as well as the ERA sandwich, can be made in a fragment-free version to significantly reduce the threat to the surroundings, including the protected vehicle itself, which is also included in this paper.
ORDERED MICROSTRUCTURES TO IMPROVE CERAMIC MECHANICAL BEHAVIOR IN SURVIVABILITY APPLICATIONS
In a desire to increase the toughness of ceramic materials for survivability applications and drawing on inspiration from natural materials such as nacre, freeze casting was investigated as a means to achieve tougher designs. A system to allow for the controlled freezing of a colloidal suspension is detailed along with the alumina formulation employed. Some initial mechanical testing and SEM imagery shows the resultant microstructures and the effect on hardness.
EFFECTS OF ORIENTATION AND VELOCITY ON HIGH-VELOCITY IMPACTS OF SPHERICAL PROJECTILES ON LEAD-ACID BATTERIES
The investigation of the damage of lead-acid batteries under projectile impacts is underexplored, yet the battery is a critical component for the normal operation of military equipment. The kinetic energy attenuation of the projectile, damage modes, and performance degradation of lead-acid batteries were explored by high-velocity projectile impact experiments from three typical orientations. The results suggest that the damage modes and performance degradation of lead-acid batteries are less influenced by the impact orientation, but are strongly correlated with the impact velocity. The rate of kinetic energy attenuation of a projectile is influenced by both the impact orientation and velocity, with higher impact velocities leading to faster energy dissipation.
THE DISTRIBUTION OF CLOTHING FIBRES IN A BALLISTIC WOUND TRACK AND ASSOCIATED INFECTION RISKS TO CIVILIAN CONFLICT CASUALTIES
Increasing conflict occurring within civilian inhabited spaces has resulted in large volumes of projectile injuries. Hospitals run by humanitarian groups are in a state of triage for months at a time, having to adequate deliver care to potentially hundreds of wounded civilians with limited resources. Infection is a known problem in those suffering conflict related injuries. This project aims to investigate how clothing fibres, one potential carrier of bacteria flora into a wound, are distributed in a bullet wound track using ballistic gelatine. It will identify any key locations which may be commonly overlooked during the debridement procedure and generate information that can help to inform the newly emerging suggestions of using a primary closure in low-velocity gunshot wounds. This paper summarises the main literature on the area, as well as the pilot study conducted as part of an MSc by Research.
ANALYTICAL COMPARISON OF THE OPTIMIZATION OF SMALL CALIBER PROJECTILES AND AIRBURST MUNITIONS FOR COUNTERING sUAS
Small Unmanned Aircraft Systems have evolved to become full-fledged weapon systems in contemporary conflicts, posing a significant threat in specific scenarios that may necessitate absolute neutralization. Unguided kinetic effectors belong to a category of countermeasures that offer a viable solution for this absolute neutralization, at a justifiable cost. Small caliber projectiles and airburst munitions are two subcategories of unguided kinetic effectors considered in the present study. The intended projectile categories are the common small calibers 5.56mm and 7.62mm and the medium calibers 30, 35 and 40mm. The aim of the work is to provide elemental insights in the operational use of the two subcategories for countering small Unmanned Aircraft Systems in an optimal configuration. The optimization process attempts to obtain a firing sequence that requires an acceptable amount of rounds for an acceptable hit probability. Since operational use require the need for prompt results, the methodology balances model accuracy and parameter value availability with computational efficiency. The present study focuses on the methodology proposition.
ANALYSIS OF THE COMBINATION OF KINETIC NEUTRALISATION AND JAMMING OF SMALL DRONES
Small unmanned aircraft systems (sUAS) are becoming prevalent in any conflicts worldwide. Although a vast majority of these devices rely on one or more radiofrequency (RF) link(s) to accomplish their mission, making RF jammers a common countermeasure in modern warfare, sUAS could still perform their intended mission, contingent on their behaviour in contested electromagnetic environments. Consequently, the optimal response to the sUAS threat may entail a combination of RF and kinetic effectors, tailored to the specific characteristics of the threat. This study explores the potential for enhancing the effectiveness of RF and kinetic effectors by using them in combination to neutralise a variety of threats, each exhibiting a distinct behaviour under RF signal loss, providing insights into their potential applications and limitations in different scenarios.
BALLISTIC LIMIT SCALING STUDIES USING LASER-DRIVEN AND CONVENTIONAL GUNS
The number of tests needed to determine the ballistic limit of a material can make screening new armor formulations or configurations a costly exercise. A relatively new technology, based on pulsed lasers, has been used to launch micro-projectiles. With this technique, 300 m-diameter steel microspheres were driven at velocities up ~500 m/s, allowing hundreds or even thousands of tests per day. The main concern when testing at very small scales is how the ballistic limits compare to their large-scale counterpart. This paper presents scaling studies performed on two aluminums Al6061-T6, and Al7075-T6, ultra-high molecular weight polyethylene (Dyneema HB80), and Kevlar® targets. For the aluminum targets, experiments were performed at scales that span two orders of magnitude: 1x scale (300 m projectile), 10x scale (3 mm projectile), and 100x scale (30 mm projectile). For the composite and fabric targets, only two scales were tested: 1x and 10x.
NUMERICAL SIMULATION AND EXPERIMENTAL STUDY ON THE CHARACTERISTICS OF ARMATURE WEAR AND CONTACT PROCESS OF SMALL CALIBER RAILGUN
During the electromagnetic railgun launch process, high temperature and high current conditions can lead to armature wear, affecting armature-rail contact and degrading launch performance. This paper starts with the analysis of the metal liquid film formation at the armature/rail contact interface. 1D and 3D models are developed based on the characteristic relational equation obtained from the melt liquid film model. These models incorporate thermodynamic equilibrium phase diagram, transient heat and mass transfer model, copper-aluminum alloy reaction model, nonlinear electrical conductivity relational equation and nonlinear thermal conductivity relational equation to analyze the temperature distribution and copper-aluminum intermetallic compounds (Cu-Al IMCs) formation in the melt liquid film. The wear mechanism and influence law of armature are explained in detail from different perspectives to understand and predict the transition and gouging phenomena at the contact interface. The model’s validity is confirmed by the results of electromagnetic launch experiments, providing insights for future structure design and material selection of the armature and rail.
MATURATION OF RAILGUN TECHNOLOGY: A EUROPEAN PERSPECTIVE
Thanks to its ability to achieve hypersonic muzzle velocities, electromagnetic railgun technology can provide effective surface-to-air defense capabilities against a variety of threats at an affordable cost. A technology maturation phase linking railgun design and evaluation with the operational requirements and constraints of military platforms is currently underway in the framework of the European Defence Fund (EDF). The French-German Research Institute of Saint-Louis (ISL) is playing an important role in this effort, based on its expertise in all aspects of railgun technology. This paper provides an overview of ISL's significant achievements and outlines the EDF-supported project THEMA. A case study in air defense operations is discussed, comparing the effectiveness of a railgun to that of a conventional gun.
HIGH-THROUGHPUT BALLISTIC LIMIT TESTING USING LASER-INDUCED PARTICLE IMPACT TESTS
Current laser-induced particle impact test (LIPIT) systems launch microspheres (diameter < 100 μm) at various target materials. Smaller spheres are typically launched at faster speeds, and those tests can shed light on the high-rate performance of nanostructures or architected materials. However, the thicknesses of common protection materials cannot be easily scaled to a similar size regime; also, larger spheres cannot be launched at sufficient speeds to accurately study the ballistic limits of those materials at achievable thickness. This work focused on evaluating various LIPIT parameters and deploying new components to increase the speed of 300 μm spheres (a size that can be used to study achievable target thicknesses). The new methods and components also resulted in a significant reduction of time required to experimentally determine the ballistic limit of common protection materials.
STUDY ON THE INFLUENCE OF SMALL CALIBER AMMUNITION HEAD COVER DEFECT ON AERODYNAMIC PARAMETERS AND FLIGHT TRAJECTORY
The ammunition hood is an important part of the ammunition structure. In this paper, based on the projectile thrown by the explosion, the concave deformation of the typical area of the hood is modeled. Through the wind tunnel test and fluid simulation calculation, the influence of the hood deformation on the aerodynamic parameters of the ammunition and the flight trajectory is analyzed. The results show that the deformation of the cylindrical section of the hood has little effect on aerodynamic parameters and flight trajectory, while the deformation of the top and circular section has a greater effect. Moreover, the deformation of the hood mainly affects the flight speed and ballistic convergence time of the ammunition, but has little effect on the inclination and angle of attack of the ballistic terminal. The research results provide reference for the structure and protection design of the head cover.
EXTERNAL BALLISTICS: PARAMETER ESTIMATION USING POD-RBF
When studying the dynamics of a bullet’s trajectory, multiple variable effects can be measured to attain predictive depiction of the bullet’s behavior. Much of this data has been studied and tested with proven success of limited predictive value. The goal of this paper is to create a reliable model for estimating the trend of how the speed of the bullet affects the drag acting on the bullet and using that inferred data to gain a rough estimate of where the bullet will hit on a given target. The idea behind this is the application of Proper Orthogonal Decomposition and Radial Basis Function to gain a prediction with limited error of where the bullet will end. What was learned through this process is that this combined process does in fact predict the trend the bullet takes with little error and does this process at a fraction of the traditional predictive time.
HIGH ORDER CORRECTION COEFFICIENTS BASED BALLISTIC SOLUTION FOR FIRE CONTROL SYSTEM
Fire control system (FCS) is the brain of any conventional weapon system which is used to estimate fire parameters such as elevation & azimuth, to engage the target. These fire parameters are estimated just before the launch of projectile after considering all measurable initial conditions. Accuracy of payload delivery to desired location depends on accuracy of predicted fire parameters, which primarily depends on the methodology of fire prediction adopted in Fire Prediction software (FPS) of FCS. FPS is generally based on ballistic solution provided by trajectory model (TM) directly or indirectly. Effects on the range for the various non-standard conditions are estimated using the correction coefficients generated by curve fit. In this paper, a comparative study has been carried out between the conventional first order curve fit as against higher order curve fit. The results obtained by this method, is further compared with six degree of freedom trajectory model.
SINGLE AND MULTI-OBJECTIVE OPTIMIZATION OF THE AERODYNAMICS OF PROJECTILES USING GENETIC ALGORITHMS
This paper is devoted to the use of genetic algorithms (GA) in order to optimize the aerodynamic of projectiles. The single and multi-objective optimization framework PYMOO [1] is used in conjunction with PRODAS software [2], a semi-empirical software assessing aerodynamic coefficients. First, single (SOO) and multi-objective optimizations (MOO) using GA are assessed on two test functions: the Gomez-Levy function [3] for a SOO under constraints, and the Binh & Korn [4] problem for a MOO. In a second time, PRODAS software is coupled with PYMOO. The first considered case is the SOO of the axial force coefficient of a 155 mm spin-stabilized projectile. The optimal configuration found by PRODAS/PYMOO is compared to additional Computational Fluid Dynamics computations in order to emphasize the dependence of the results to the aerodynamic prediction tool. Finally, both SOO and MOO are performed on a guided 155 mm fin-stabilized artillery projectile equipped with a Canard Actuation System (CAS). The single-objective optimization is based on the maximization of the normal force coefficient CNα whereas the MOO adds the drag coefficient CXO as a second objective.
6-DoF MODEL FINE-TUNING: AERODYNAMIC COEFFICIENTS, QUATERNIONS AND NUMERICAL SCHEMES
This paper addresses key challenges in 6-DoF projectile trajectory simulation using VTraj, a software developed by the Royal Military Academy of Belgium and compliant with NATO’s AEP-96 standard. It focuses on the critical importance of aerodynamic coefficient interpolation, quaternion normalization, and numerical scheme selection to ensure accurate trajectory prediction. The study highlights that selecting an appropriate integration frame eliminates the need for explicit quaternion normalization, preserving numerical stability. Aerodynamic coefficient interpolation is shown to significantly impact accuracy, with drift discrepancies of up to 6% depending on the interpolation method. Finally, a comparison of numerical schemes reveals that the 4th-order Runge-Kutta (RK4) method achieves nearly the same accuracy as the higher-order RK78, while reducing computational time by a factor of at least 1.8. This work provides valuable insights for researchers conducting high-fidelity exterior ballistics simulations.
PREDICTION OF THE DISPERSION OF SNIPER WEAPON SYSTEMS BASED ON STOCHASTIC SIMULATIONS
The dispersion of sniper weapon systems is influenced by various factors contributing to the overall error budget. This paper presents a comprehensive approach to the computation of the error budget using stochastic simulations applied to long range shooting. By leveraging probabilistic modelling and Monte Carlo simulations, we analyze how each source of error affects the weapon system’s accuracy and precision. Key variables, including wind velocity, temperature, muzzle velocity variations, and error in measurements, are incorporated into the model to reflect real-world operational conditions. The results provide valuable insights into the critical components of the error budget, aiding in the refinement of weapon system design and training methodologies. This study contributes to enhancing the operational effectiveness of weapon systems by quantifying precision-degrading influences under a wide range of conditions.
EFFECT OF ROTATING TAIL ON THE AERODYNAMICS OF GUIDED ARTILLERY SHELL
Guided artillery shells use aerodynamic control force generated by canards in order to maneuver the shell. Due to low aspect ratio of the guided shells, the flow over the tail fins is affected due to canard deflections (See Figure-1). Freely rotating tail is used in guided shells in order to avoid the adverse rolling moment. Rotation of tail fin plays a crucial role in the aerodynamics of the artillery shell. In the current study, effect of rotation rates of tail fin on various aerodynamic coefficients is studied using computational fluid dynamics (CFD). The maximum tail fin rotation rate is estimated by using unsteady CFD simulation. The rotation of the tail fin is simulated by employing overset mesh and 1 DOF model in ANSYS Fluent CFD Software. Various aerodynamic coefficients are estimated for canard control deflection with tail rotation rate varying from 0 to maximum value. Aerodynamic coefficients show a significant change with reference to non-rotating tail simulation. However, for the rotating tail simulations the tail rotation rate has very minor effect on the aerodynamic coefficients.
FORCE MEASUREMENTS ON SMALL CALIBER SUPERSONIC PROJECTILES USING AN EXTERNAL FORCE-TORQUE TRANSDUCER
In this work, we present a preliminary study on the use of an external force-torque transducer for the aerodynamic characterization of projectiles in small supersonic wind tunnels. We describe the implementation process of the sensor in our test section, using a 5.56 mm NATO M855 projectile model to carry out a series of experiments where we identify the limitations of different design and flow configurations. We present a feasible design which we then use to investigate the effects of model scale in the measured aerodynamic forces at Mach 2.5. The trends observed in the results demonstrate the non-negligible contributions of the projectile to the total force measurements. Finally, we propose a preliminary force decomposition procedure to isolate the projectile drag, based on scaling arguments and Kármán-Moore theory, with which we recover reasonable agreement in zero-yaw drag coefficient with live firing data from the literature.
COMPARATIVE ANALYSIS OF FLIGHT TEST TRAJECTORY DATA FROM PHOTOGRAMMETRY AND CFD FOR AN AIR-DELIVERED STORE
Store separation studies are one of the most critical studies to be carried out during the development of an aircraft delivered store as it involves the safety of the pilots and the aircraft. These studies bring out the safe release envelop of different stations for the stores under study. The pre-flight simulations are necessary for obtaining flight clearance from the certifying agencies for military airworthiness. The preliminary flight tests are usually carried out for benign conditions in the operating envelop and the post-flight simulations with the initial conditions as obtained from the flight data recorder validates the simulations carried out and instill confidence in carrying out the flight trials for the extreme points of the flight envelop. One of the ways of extracting the trajectory parameters of the store separation from the aircraft is by the photogrammetry of the video of the store separation. In the current study, the trajectory parameters of the store separation of the store under study were extracted using a commercial software, TrackEye and were compared with the unsteady 6DoF coupled CFD simulation carried out using Simcenter STAR-CCM+ + CFD Software.
TOWARDS LOW-COST, HIGH-RELIABILITY ON-BOARD DATA LOGGING FOR LARGE-CALIBRE ARTILLERY EXTERIOR BALLISTICS MEASUREMENT
During the development phase of large-calibre munitions, numerous firing tests are conducted to evaluate projectile dynamics and performance in flight. While exterior ballistic data is often collected using traditional methods, certain dynamic flight events are best captured through on-board sensors and data loggers, assuming the test range allows for projectile recovery. This paper presents a compact electronic logger designed to measure the arming time of 155 mm artillery fuze Safe Arming Device (SAD) and record in-flight data, enabling cost- and time- efficient testing. This study covers the embedded design, development, and optimisation of the data logger capable of digital and analog measurement. Key design aspects discussed include launch survivability of non-military specification electronic components, low-power optimisations, power source selection, setback switching, and potting methods. The arming time of an artillery SAD is determined, and the dynamic test data is presented. Finally, the reusability of the data logger is discussed, along with recommendations for future work.
A STUDY OF THE ACCELERATION TRANSFER INTERFACE AND ITS INFLUENCE ON THE BOUNDARY LAYER TRANSITION AND DRAG CHARACTERISTICS OF A 30 MM KINETIC ENERGY PROJECTILE
This study investigates the influence of the acceleration transfer interface on boundary layer transition and drag characteristics of a 30 mm kinetic energy projectile (KEP) using an allspeed transition model. The acceleration transfer interface, represented by annular grooves, imparts force and acceleration to the projectile during its launch but also interacts aerodynamically with the projectile's external flow and influences its performance. The presence of grooves introduces complex flow interactions, including micro-shocks, pressure fluctuations, and local flow separation, which affect the boundary layer state and drag. Since the terminal effectiveness of the projectile depends on the impact velocity, reducing the velocity decay due to the drag is an efficient way to improve the aerodynamic performance of the projectile. Numerical simulations reveal that grooves in the laminar boundary layer trigger the early transition and increase the friction drag, while those in the turbulent boundary layer have a minimal impact on the friction drag. The early transition due to grooves in the laminar boundary layer amplifies shear stress and turbulent energy production, degrading efficiency. These findings aid in optimizing groove geometries and location to minimize the drag while ensuring effective acceleration transfer, with implications for high-speed projectile design and ballistic efficiency improvements.
EFFECT OF MICRO-VORTEX GENERATOR GEOMETRY ON SEPARATION CHARACTERISTICS OF SUPERSONIC INLET
Shock boundary layer interaction (SBLI) for supersonic inlet can cause flow separation which can lead to increased drag, unstart conditions resulting in reduction in performance and efficiency. One of the important techniques of SBLI mitigation is use of micro-vortex generator (MVG) located upstream of the shock impingement in order to control the flow separation. In the current study, effect of shape of MVGs is studied using computational fluid dynamics (CFD). The supersonic inlet flow with and without MVGs is simulated using ANSYS Fluent CFD Software. Shock generated due to cowl generates an adverse pressure gradient causing flow separation inside the inlet. The presence of MVG generates vortices energizing the boundary layer and thus reducing the separation length.
RECONSTRUCTION OF DATA FROM TABULAR FIRING TABLES FOR TUNING FCS BALLISTIC SW
For FCS ballistic SW tuning, it is necessary to use real information and data valid for the supported barrel weapon system. This information can be found in the corresponding Tabular Firing Tables (TFTs). The basic problem is that the data in TFTs contain printing errors and are rounded too roughly. This means that without their approximation they cannot be used directly to tune ballistic SW. Unfortunately, most TFTs do not contain all the necessary data for tuning. These are mainly TFTs for direct fire at ground targets, therefore we have chosen as an illustrative example the 12.7 mm Heavy Machine Gun M2HB and cartridges with Ball M2 or AP M2 projectiles. The article uses an original procedure for reconstructing the data needed for tuning. In addition, an approximation of the zero yaw drag coefficient cD0 for the above-mentioned projectiles is presented.
ENHANCED COMPUTATIONAL METHOD TO PREDICT FIRE PARAMETERS IN AN ARTILLERY FIRE
This paper proposes an enhanced computational technique to compute fire parameters such as firing angle and azimuth, during fire prediction in an artillery fire. The current fire prediction methods, are in-general based on two approaches wherein either a firing table containing several look-up tables is used in conjunction with simple mathematical equations to manually compute the fire parameters for non-standard conditions of fire or alternatively computing the fire parameters iteratively using a trajectory-based fire prediction software. Trajectory-based fire prediction algorithms are much accurate and usually begins with an initial guess firing angle, obtained by interpolating the range-elevation dataset, computed for standard conditions. A step further, to reduce the number of iterations, the final firing angles computed using a digital firing table is more often used as guess firing angle, wherein the corrections to range and line for every non-standard parameter is computed from a set of polynomial equations obtained by curve fitting the dataset. This paper proposes the use of machine learning based algorithms which are much robust and accurate as compared to the polynomial functions obtained by traditional curve fit techniques.
ATTITUDE ESTIMATION AND PRECISION GUIDANCE OF A SPINNING ARTILLERY SHELL
Guided munitions enable precise targeting and minimal collateral damage. Accurately determining an artillery shell’s orientation in flight allows real-time trajectory adjustments for maximum effectiveness. Spinning enhances stability but complicates attitude estimation due to dynamic disturbances. This research explores cost-effective techniques to estimate the attitude of spinning artillery shells using a magnetometer, accelerometer, GPS, and gyroscope integrated into a Kalman filter framework. The estimated orientation (roll, pitch, yaw) enables real-time trajectory corrections. A guidance algorithm will refine the shell’s path based on its position, orientation, and target coordinates. This system is critical for modern defense, allowing remote-launched munitions to strike with high precision while reducing costs. By continuously adjusting deviations from the intended flight path, it enhances accuracy and aligns with advanced military strategies focused on precision and efficiency.
AEROMECHANICAL ANALYSIS OF A NOVEL MORTAR-GUIDED MUNITION WITH WING CONTROL AND ENHANCED GLIDING CAPABILITY
This paper presents the aerodynamic design, analysis, and aeromechanical characteristics of a novel mortar-guided munition with a single set of cruciform wings, which provide both gliding and steering capabilities. This streamlined design, using a single set of aerodynamic surfaces, simplifies the guidance and control system by delivering lift and control forces without the complexity of multiple lifting surfaces traditionally required for independent gliding and steering. The wing control scheme enables pitch, yaw, and roll control at relatively low angles of attack, with an almost linear aerodynamic response throughout the flight. Engineering aerodynamic methods, potential flow method, and Computational Fluid Dynamics (CFD) were employed to design and analyze the configuration across both the ballistic and gliding-guided phases. Comprehensive results are presented, detailing the full set of aerodynamic coefficients needed for aeromechanical analysis and simulation. A preliminary aeromechanical analysis was conducted to determine the performance of the munition in terms of the operational ranges, control scheme, and trajectory attributes.
A CONTROL ALGORITHM FOR SPIN-STABILIZED PROJECTILES BASED ON MODEL PREDICTION AND ATTITUDE COMPENSATION
Aiming at the problems of low trajectory control accuracy caused by high rolling speed of rotary stabilized projectile, such as strong aerodynamic and dynamic coupling of pitch, yaw and roll channels, high model nonlinearity and uncertainty, and insufficient maneuverability, this paper proposes a method combining model prediction method with control angle compensation and prediction error estimation. In this control algorithm, the model prediction method whose prediction error is estimated in the free flight duration is proposed to increasing the prediction accuracy and improve the control efficiency. Moreover,to cope with modeling and control system errors, an compensation angle is deduced by comparing the actual attitude angle of the projectile in the control state with the attitude angle predicted by the model in the control period. The feasibility and effectiveness of the model prediction controller with angular compensation is verified through closed-loop flight simulations with measurement, control, and condition uncertainties, and it is compared with the traditional model prediction control algorithm. The results indicate that the designed controller can evidently decrease the distance between the impact point and target under different uncertainties.
AN EVALUATION OF HOLLOW POINT OGIVES ON AEROSPIKE PROJECTILES
An aerospike projectile base is an inverted rocket nozzle shape intended to reduce the base drag on a projectile by forcing isentropic flow over a portion of the projectile base and reducing the size of the base recirculation region. Initial studies on aerospike bases showed a significant reduction in overall drag compared to a control projectile shape with the same ogive shape. Both the aerospike and control projectile were fabricated as monolithic copper based upon the shape of a well-studied Sierra 168 grain Boat Tailed Hollow Point (BTHP) reference projectile. It was observed in testing that the overall aerodynamic drag of the monolithic control projectile was significantly higher than the published drag of the reference projectile despite being ballistically similar with the exception of the hollow ogive cavity (hollowpoint). The original aerospike study was recreated with the addition of drilled hollow points in the control and aerospike projectiles. A statistically significant reduction of approximately 4% in aerodynamic drag was measured in both the control and aerospike projectile at Mach numbers greater than 2 in testing. No reduction in drag was observed in Mach numbers below 2. The hollowpoint did stabilize the control projectile at low supersonic and transonic speed allowing a better comparison of the aerospike to the control projectile.
AN EVALUATION OF LIMIT CYCLE MOTION AND ITS IMPACT ON AEROSPIKE PROJECTILES
An aerospike projectile base is an inverted rocket nozzle shape intended to reduce the base drag on a projectile by forcing isentropic flow over a portion of the projectile base and reducing the size of the base recirculation region. Initial studies on aerospike bases showed a significant reduction in overall drag compared to a control projectile shape with the same ogive shape. The aerospike design assumes zero angle of attack and the initial studies were conducted on projectiles that closely matched that assumption in flight. Some projectiles such as the M107 155mm artillery projectile are known to have a limit cycle motion where the average angle of attack is significant. This study places aerospike bases of inlet Mach 1 and outlet Mach 1.2, 1.4, and 1.6 on a 1:1000 scale model of the M107 projectile. The impact of the limit cycle motion on aerospike performance is then studied through live fire experiments.
A NOVEL TECHNIQUE & TIME EFFICIENT ALGORITHM TO ESTIMATE MISS DISTANCES IN SIMULATION OF STORE SEPARATION FROM FIGHTER AIRCRAFT
This paper introduces a novel software tool for accurately estimating the miss distance of a store separating from an aircraft during flight. The tool is based on trajectory data from 6- Degrees of Freedom (6-DoF) coupled Computational Fluid Dynamics (CFD) simulations. The minimum distance between the store and aircraft is usually computed during the post processing which involves processing millions of surface mesh points, a computationally intensive task. Traditional methods, which compute distances sequentially, can take over 32 hours per simulation. The proposed solution uses Python-based multiprocessing and vectorization techniques to parallelize the calculations, significantly reducing computation time to just 45 minutes. By optimizing resource utilization and employing advanced matrix operations, this tool computes at least 40 times faster, while maintaining the same accuracy. This breakthrough facilitates faster analysis of store separation simulations and has significant implications in project workflow.1
EFFECT OF ROLL AUTOPILOT ON BALLISTIC FLIGHT OF A GUIDED AMMUNITION
The Vulcano 155 Guided Long Range is a guided, aerodynamically stabilized, sub-caliber ammunition with a multi-role capability, able to be equipped with three different fuzes (i.e. RF, SAL and FAR-IR). A particular lateral deflection of V155GLR was recorded when verifying a new guiding mode in which the ammunition is in ballistic flight. By in depth analyzing this behavior, it was observed that contrary to a proper ballistic ammunition (e.g. V155BER), the V155GLR has a different lateral deflection. An investigation was done in order to assess the main cause of this peculiar effect. The analysis ends with finding the roll rate autopilot as the major responsible of this effect. This paper shows the results obtained in the past test campaigns in the Alkantpan Proving Ground (APG) South Africa, the effect of either switching on or switching off the autopilot, and the effect of the order of magnitude of the controlled roll rate.
EFFECTS OF THE SINTERING PROCESS ON ADDITIVELY MANUFACTURED COPPER PROJECTILES
Additive manufacturing (AM), particularly three-dimensional (3D) printing, has emerged as one of the fastest growing freeform fabrication techniques [1]. This form of manufacturing has spread throughout multiple industries including aerospace, automotive, and defense [1]. Among the growing range of materials available for 3D printing are plastics, ceramics, and metal/polymer composite filaments. This technique involves adding progressive layers of the material until the desired product is created. Utilizing metal/polymer composites typically requires a post-processing debinding and sintering step to fully consolidate the material into a dense metal product [2]. However, this process can be costly due to the need for hightemperature furnaces, specialized consumables, and extended processing times. Additionally, the sintering process includes complex material science, such as volumetric shrinkage, to determine relative density and deformation of the 3D printed sample [3]. This study investigates the potential for bypassing the sintering process in 3D-printed copper projectiles to evaluate the effect on key ballistic characteristics, including muzzle exit velocity, soft recovery entrance velocity, mass recovered during the soft recovery and mass lost of the projectile. This research aims to determine whether the sintering process is essential for achieving these ballistic properties successfully, or if similar performance can be achieved without it. Experimental testing will assess the performance of green and sintered AM copper 12-gauge rifled shotgun slugs. A soft recovery system was utilized to catch the projectiles while minimizing the deformation associated with recovery. Ultimately, this research will contribute to a deeper understanding of the trade-offs between post-processing requirements and performance in AM copper projectiles.
A STUDY ON MUZZLE VELOCITY ESTIMATION FOR NAVAL GUN PAC (PRE-ACTION CALIBRATIONS) FIRINGS USING NONLINEAR EQUATIONS OF MOTION
Pre-Action Calibrations (PAC) are critical for ensuring the accuracy and reliability of naval gun systems. PAC involves firing rounds at a safe bearing and range to analyze muzzle velocity (MV) and Mean Point of Impact (MPI) for correcting bias errors. Radar tracking identifies impact spots and measures projectile velocity at corresponding positions on an imaginary target. This data is used to estimate MV and adjust the Fire Control System (FCS) for improved precision. Factors such as propellant temperature, barrel wear, mass variation, and platform motion significantly affect MV, while meteorological conditions influence measured velocities. These non-linear factors make linearized methods inadequate for accurate MV estimation. To address this, a new method leveraging non-linear equations is proposed, enhancing MV estimation under non-standard conditions. This approach is particularly beneficial for systems like Gatling gun-based CIWS (Close-In Weapon System), where MVRS installation is not feasible, improving firing precision and operational readiness in challenging environments.
PENETRATING URANIUM REAL FRAGMENT EXPERIMENTS FOR CONTAINMENT TRIALS (PURFECT)
In order to develop fragment mitigation solutions, fragment simulating projectile trials are often undertaken. In these, cylindrical rods are fired into targets using high velocity launchers. One key assumption of this methodology is that the projectile penetration is representative of the penetration from real explosively-formed fragments, which has not previously been investigated. Here we detail the first series of trials in which explosivelyformed fragments, which were soft-captured in previous trials, were launched from a gas gun at velocities of approximately 1-2 km.s-1 into AA6061-T6 targets. To the best of our knowledge, a first. Whilst gathered data displayed significant scatter, the results do provide confidence that fragment simulating projectile rods are accurate simulants of real fragments in impact assessments. A method of simulating the real fragment impacts was also developed, with simulations of the trials undertaken and the results of the simulations matched reasonably well to the measured penetration depths.
INVESTIGATION OF DIFFERENT GLASS AND ALUMINIUM ALLOY LAYERS FOR FRAGMENT MITIGATION
A series of fragment-simulating projectile trials has been conducted to investigate the performance of various glass and aluminium alloy targets as fragment mitigation barriers. Steel 304L rods were fired into layers of the material at velocities between 700 – 2000 m.s-1 using a powder-propellant launcher. Soda lime glass, toughened soda lime glass, laminated soda lime glass and borosilicate glass were tested to rank the ability of the different glass types to mitigate the projectiles. Three aluminium alloy grades, 5083-O, 6061-T6 and 7075-T6, were then tested to investigate projectile penetration depth with increasing alloy strength. Lastly, the 7075 alloy was tested in both -T6 and -T7 temper designations to compare the failure mechanisms of the alloy in these two heat treatments. Supporting Lagrangian simulations of the firings were also undertaken in Ansys Autodyn.
STUDY ON THE PRESSURE CHARACTERISTICS IN LIQUID-FILLED CONTAINER SUBJECTED TO SHAPED CHARGE JET IMPACT
The pressure characteristics caused by shaped charge jet penetration in liquid-filled containers were investigated using the Structural Arbitrary Lagrangian-Eulerian (S-ALE) method in ANSYS/LS-DYNA. A ballistic experiment was conducted in parallel to validate the numerical model. The results indicate that the pressure pulses in the liquid are primarily caused by the propagation and reflection of the shock wave generated by the jet penetration. The peak pressure exhibits an initial increase, followed by a decline, along the ballistic direction. Additionally, along the radial direction, the peak pressure continuously decreases. The research findings provide guidance for the theoretical modeling of pressure waves and the analysis of the structural response of containers.
COMPARATIVE ANALYSIS OF ROMA PLASTILINA NO. 1 AND WEIBLE PLASTILINA FOR BALLISTIC TESTING APPLICATIONS
In the field of body armour testing, the consistency and predictability of witness materials are crucial for accurately assessing the threat posed by projectiles. Roma Plastilina No. 1 modelling clay (present in different body armour standards like NIJ and CAST) has long been the typical material for validating body armour material in ballistic tests, offering welldocumented properties in terms of consistency, density, and plasticity. However, the growing demand for alternative materials has led to the introduction of Weible Plastilina (current in the VPAM norm), a newer contender in the field. The work presented here aims to provide a comprehensive comparative analysis between Roma Plastilina No. 1 and Weible Plastilina, by evaluating their characteristics, and their overall suitability for use in ballistic testing. Through controlled experimental tests, including standardized penetration tests according to the NIJ0101.04 level IIIA and VPAM APR 2006 level 3 and level 4, the materials response to different projectile impacts were tested, with particular attention to the differences in performance under varying temperature conditions according to the different norms. The purpose of this research is not to rank the different modelling clays but inform the ballistic community on how the two materials behave during ballistic tests, providing insights that could influence future material choices for ballistic testing applications.
NUMERICAL AND EXPERIMENTAL STUDIES ON THE 9 x 19 MM BALL RICOCHET RISK IMPACTING REGUPOL® E43 SHEET
Rubber-like materials due to their costs and properties are often used for broad civil and military applications starting from outdoor children playgrounds floor pavement up to indoor shooting ranges bullet traps or ricochet mitigating surfaces. For a notorious trade mark, namely Regupol® E43, mechanical and ballistic tests were performed in order to look into some of its main mechanical and ballistic properties. Mechanical tests performed on Regupol® E43 aimed to evaluate the dependency of engineering stress on engineering strain for quasi-static loading and its ability to absorb energy. The ballistic tests were focused on evaluating the ballistic limit and a critical angle above which the risk of ricochet for a 9 x 19 mm ball shoot against a Regupol® E43 sheet is no longer possible for meaningful impact velocities. The approach used was twofold, experimental and numerical. The numerical results were compared against experimental ones showing a fair correlation between the two sets. This document is an extended abstract of a paper submitted to a peer-reviewed journal.
EFFECTIVITY OF A M42 SHAPED CHARGE AS A FUNCTION OF STAND-OFF DISTANCE
This orienting study is about the effectivity of shaped charges as a function of stand-off distance. To improve the protection of military vehicles, it is necessary to collect more information about the effects of shaped charges. Both penetration depth of the jet into C45 carbon steel and the distribution of fragments caused by the detonation of an M42 explosive were determined. The explosive of the M42 shaped charge is Composition A-5. The experiments were performed at eight different stand-off distances from 0 mm to a maximum of 250 mm. This research shows that the penetration depth increases with stand-off up to about 100 mm. After this maximum the penetration depth decreases. The number of observed impact points from fragments of the shaped charge increases with increasing stand-off distance. Two skewed distribution functions have been tentatively fitted to the impact point distributions. Possible future research is discussed.
DEVELOPMENT OF A STANDARDIZED PROJECTILE FOR KENLW
The NATO STANREC 4744 outlines test methodologies for assessing kinetic energy nonlethal weapons (KENLW). The current validation process uses a commercially available projectile, but it has drawbacks: relatively high cost, limited availability in the USA and Canada, and lack of control over the projectile's consistency. To address these issues, a standardized Non-Lethal Bullet Simulating Projectile is proposed. Three candidates are considered: foam top and plastic body (FDM 3D printing), fully resin (SLA 3D printing) and fully plastic (FDM 3D printing). The goal is to identify a candidate that ensures availability, reproducibility, and repeatability for validating and calibrating surrogates. The selected solution will be tested on current surrogates to ensure that it meets these requirements.
DYNAMIC FRAGMENTATION AND PERFORATION BEHAVIOR OF REACTIVE PELE PROJECTILES
This study investigates the fragmentation dynamics and damage characteristics of Penetrators with Enhanced Lateral Effects (PELE) using inert (PTFE) and reactive (Viton/Al, BDOFP/ CuO/Al) fillings. High-velocity impact experiments coupled with Smoothed Particle Hydrodynamics (SPH) simulations were performed to analyze axial and radial velocities of the projectile, fragment dispersion, and witness plate perforation. Reactive fillings significantly enhanced lateral dispersion and induced broader fragment distributions and extensive witness plate damage, as evidenced by larger central and dispersed perforations. Inert PTFE demonstrated limited lateral effects, retaining higher axial velocities and more localized damage. Numerical simulations aligned well with experimental observations qualitatively, capturing key trends despite some deviations in radial dispersion. This study highlights the critical role of material reactivity and energy redistribution in governing PELE fragmentation and impact damage. The findings offer insights for optimizing projectile designs in defense and engineering applications requiring enhanced lateral effects.
UNDERSTANDING BALLISTIC LIMIT SCALING LAWS
A series of critical perforation velocity experiments have been performed, where tungsten alloy spheres were shot at thin mild steel plates. The experiments were repeated at four geometric scales; with projectile diameters of 1.5, 3, 5, and 10 mm; and corresponding plate thicknesses of 0.872, 1.7, 2.9, 5.8 mm. It was found that the critical velocity for perforation decreased when the scale increased. The experimental results were replicated with multiple numerical simulation setups, and the simulation settings were adjusted in order to best replicate the decrease in critical velocity observed for larger scales. A simulation including a softer steel in the center of the target plate, which was softer in proportion to the measured cross-section Vickers Hardness of the corresponding experimental target, produced the best agreement with the experimental results.
FRAGMENTATION EFFECTS ON LETHALITY RESULTS
In order to evaluate the lethal performance of a given weapon, it is necessary to determine the characteristics of the fragments’ spray generated by the detonation. Those trials are carried out by the CEA with static detonation tests, also known as arena tests, and the fragmentation is simulated in a numerical software (PROMETER) to calculate the effectiveness of that weapon or the vulnerability of the target. The first aim is to evaluate the impact of those numerous small fragments on lethality calculations. Furthermore, a lethality assessment is done to evaluate the effects of the fragmentation parameters on lethality results. Those parameters are also determined through arena tests but can be evaluated numerically with FREM or numerical simulations.
WATER AS INTERLAYER FOR NON-EXPLOSIVE REACTIVE ARMOUR: NUMERICAL SIMULATION AND EXPERIMENTAL VALIDATION
Non-Explosive Reactive Armour is composed of a sandwich of two inert plates and an interlayer of a soft material. Numerical simulation on NERA in interaction with shaped charge jets is complex, because of the immense pressure generated in the interlayer and the difficulties to identify the material parameters needed for numerical simulation in the relevant pressure regime. In this work, water is used as interlayer material for NERA. To take possible phase transitions in the interlayer into account, the Tillotson Equation of State was chosen for the numerical model of the water interlayer. The numerical simulations have been done with the -SPH code of Abstrao. The dynamic reaction of the NERA to the impact of a shaped charge jet and the resulting disturbance of the jet was very well predicted by the numerical model. This was validated experimentally with a state-of-the-art X-ray cineradiography setup.
EDGE EFFECTS IN FLYER PLATE-LONG ROD PROJECTILE INTERACTIONS
Flyer plates from explosive reactive armor can be efficient disruption components in the defense of armored vehicles against kinetic energy threats. Edge effects in interactions between flyer plates and long rod projectiles occur when the projectile strikes the flyer plate close to the plate edge or when the plate strikes the projectile along its body. The abrupt loading or unloading that then occurs may enhance or reduce the desired effect of deforming and fracturing the projectile. It is found that the edge effect leads to different deformation and fracturing behavior of projectiles, indicating that the phenomena should be studied further.
CLOSE-RANGE POST-RICOCHET BEHAVIOUR AND GYROSCOPIC STABILITY OF SMALL-CALIBRE PROJECTILES
In this work, post-ricochet behaviour of small-calibre projectiles is studied. It builds upon recent work in which remarkable post-ricochet yaw behaviour was observed on witness screens. We think this behaviour is influenced by the gyroscopic stability of the projectile. Here both witness screens and 3D high-speed camera videos were used to study the closerange post-ricochet behaviour of projectiles having different gyroscopic stabilities. Trespa® Meteon® and XAR500 steel are used as target materials. The hardnesses of the Trespa® Meteon® and steel plates were measured. Results are compared with earlier findings on ricochet behaviour. The shape of the post-ricochet marks observed is dependent on the postricochet flight of the projectile, i.e. whether the projectile tumbles or not. Finally, possible future ricochet research will be discussed.
BODY INJURIES CAUSED BY RESIDUAL JET MATERIAL AND ARMOR SPALLS AFTER IT HAD BEEN PERFORATED BY THE PG-7 HEAT PROJECTILE
The study aimed to investigate the effects of the armor spalls produced by the jet material and the residual jet material after the explosion of the PG-7 HEAT projectile on the human body. The study concludes that if the jet material perforates the vehicle's armor, the residual jet (even the one on the verge of armor penetration) constitutes a lethal threat to the crew of the attacked vehicle, and it is challenging to protect against the mentioned threat. Additionally, it was shown that when the stream passes through the human body, the bone fragments generated may constitute secondary projectiles that pose a danger to people outside the area of the stream passage. However, armor spalls, on the other hand, are a less severe threat, as many of them can be stopped by spall-liners.
PURSUING SMALL-SCALE MEASURES OF PENETRATION RESISTANCE IN Ti-5553 ALLOY
This work was originally proposed to illustrate the performance of a particular set of differently processed Ti-5553 plates under dynamic threats. It became clear that the larger question, at present, is whether the small-scale shaped charge design of an RP-4 detonator can be employed to efficiently explore the dynamic penetration resistance of representative test articles. The initial penetration testing that employed three variants of thermomechanical processing of Ti-5553 plates appeared to demonstrate that there was a noticeable difference in their performance. The remaining pertinent question was regarding the variation in the shaped charge performance and how it compares to the variation from the three titanium plate tests. Based on the limited testing presented here the RP-4 shaped charge detonator appears to have an average depth of penetration in 6061 aluminum of 90mm with a 1.5CD stand off.
VELOCITY DECAY IN BALLISTIC GELATIN USING EXPERIMENTAL AND COMPUTATIONAL ANALYSIS
Ballistic gelatin has long been used as simulant for the evaluation of small caliber threats against soft targets. The use of gelatin as a soft target simulant date back to the 1960’s and has been an area of active research since. As a substitute for living tissue ballistic gelatin allows for a reproducible, ethical, and cost efficient medium for obtaining experimental data. Experiments and numerical studies carried out at Picatinny Arsenal, US Army, Armaments Center, New Jersey, have shown that while good agreement can be achieved with traditional material models it is usually only valid over a range of impact velocities and projectile weights. This study was also limited by the limited experimental data points obtained. Follow-up experiments were conducted involving a 15.8 grain sphere impacting gelatin at velocities ranging from 2000 ft/s to 500 ft/s. The use of high speed cameras and tracking software during the penetration event allowed for the capture of the velocity decay curve for each experiment. Finite Element impact simulations were then created using the Finite Element code IMPETUS AFEA. The use of the surface SPH method is explored in this study. Previous numerical experiments have shown advantages to this approach, such as eliminating advection errors due to Eulerian material boundaries. The ballistic response of the simulations was compared to test data to calibrate material properties. Data from previous studies suggests that ballistic gelatin shows a strong strain rate dependency. Due to this and the limitation shown from previous research, this study will examine the need of rate-dependent material models for the response of the gelatin. The results from experimental tests are compared with the numerical models to determine the best approach to capturing the ballistic response of gelatin over a wide range of impact velocities.
BODY INJURIES CAUSED BY SHRAPNEL FROM THE EXPLOSION OF OF-843B 120 MM MORTAR AMMUNITION
Both conventional and terrorist weapons are designed to produce multiple wounds with the maximum number of casualties. Fragments are still the most common cause of wounds in armed combat. On today’s battlefield, up to 90% of casualties are secondary to fragmentation wounds. The aim of the study was to investigate the effects of the shrapnel produced by the OF-843B 120 mm mortar shell on the human body. Our paper includes photographic and Xray footage of the conducted experiment and its effects on the human body. The conclusion of the study is that fragments generated by the detonation of OF-843B mortar ammunition at a distance of 10 meters cause deep (up to 25 cm), extensive, differently shaped temporary cavity channels containing multiple fragments of various shapes and sizes.
SHAPED CHARGE FIRING THROUGH FUEL TANK WITHIN A GENERIC VEHICLE VOLUME
Attack of a shaped charge jet (SCJ) against a vehicle may result in perforation of the fuel tank, which subsequently can lead to the spreading of fuel inside the vehicle and an increased risk of fire. To determine the probability of ignition and the effect on the passengers, test where conducted, where an SCJ was fired through a fuel tank inside a pressure vessel. Through highspeed videos, temperature and pressure measurements it was concluded that there is a high probability that the fuel will ignite if an SCJ penetrates the fuel tank.
QUALITATIVE AND QUANTITATIVE EVALUATION OF IMPACT DAMAGE TO CONCRETE TARGETS USING 3D-SCANNING TECHNOLOGY
For the penetration of porous materials, damage plays an important role. However, the systematic evaluation of damage is a challenge. This paper presents a method using the example of projectile impact tests on ultra-high-performance fiber-reinforced concrete that allows the qualitative and quantitative assessment of damage to perforated finite targets. Modern 3D-scanning technology is utilized for this task. The advantages of damage assessment using 3D scanning technology are presented in this paper.
NUMERICAL MODELLING OF ADDITIVE MANUFACTURED HIGH-STRENGTH MARAGING STEEL TARGETS UNDER BALLISTIC IMPACT BEFORE AND AFTER HEAT-TREATMENT
The combination of ultra high-strength and the flexibility of additive manufacturing (AM) makes maraging steel produced by laser powder-bed fusion an exciting prospect for optimised armour systems. Good ballistic performance has been found in experimental studies, despite a tendency for fragmentation of the high-strength heat-treated maraging steel, exacerbated by AM defects. Fragmentation is a long-standing challenge in the numerical modelling of ballistic impact. This study evaluates the ability of two different failure modelling approaches to capture fragmentation in finite element simulations using the IMPETUS Solver: node-splitting and element erosion. The predicted ballistic limit velocity was conservatively within 10% of the experimentally determined value using both failure models for the non-heat-treated AM targets, despite only simple measures taken to account for the AM-induced anisotropy. The element erosion technique was found to under-predict the ballistic limit velocity of high-strength, heat-treated targets, with significant fragmentation, by 13%, compared to only 2% for node-splitting.
EXPERIMENTAL STUDY OF THE BALLISTIC RESISTANCE OF TRANSPARENT SPINEL AGAINST TUNGSTEN CARBIDE CORE PROJECTILES
Transparent materials are some of the most critical components in the protection of light armored vehicles. It has been demonstrated that significant weight reductions can be achieved in the defeat of steel core projectiles, compared to conventional glass-based armor, when a transparent ceramic is used as the strike face on a glass-polymer laminate. In order to assess the efficiency of spinel types of different microstructures, against projectiles with tungsten carbide core, Depth of Penetration (DoP) tests were conducted. In these tests, spinel plates were glued either directly on a thick polycarbonate backing, or on a soda-lime glass plate, placed between the spinel and the polycarbonate backing. All impact tests were performed using 7.62 mm AP projectiles with tungsten carbide core at a nominal impact velocity of 930 m/s. One commercial grade of transparent spinel ceramic and four distinct spinel grades with defined microstructures, manufactured by the Fraunhofer Institute for Ceramic Technologies and Systems (IKTS), were tested. The test results demonstrated an increase of the ballistic resistance with increasing spinel thickness. For spinel plate thicknesses of 8 mm and more, significant differences in the performance were observed, depending on the microstructure. Target and projectile fragments were extracted from the target chamber and analyzed. The DoP-results indicate that coarser-grained spinel variants have a higher ballistic resistance against tungsten carbide core projectiles.
FAST-RUNNING MODEL FOR THE PENETRATION PERFORMANCE OF NON-IDEAL SHAPED CHARGE JETS AND INTERACTION WITH ERA
In this paper, an analytical model for the penetration of a shaped charge jet is presented, and it is shown that the model is able to predict the penetration of a jet to a high degree when compared to experimental data. The model takes inspiration from already existing models for jet penetration such as HIPEN. The model is designed to be fast enough to be useful as a tool with Monte Carlo simulations, but detailed enough to handle various types of targets and target configurations, including explosive reactive armor. The non-ideality of real jets is also modeled to improve the model’s accuracy at longer standoff and to estimate the variation in the penetration.
METHODS FOR MEASURING MATERIAL PARAMETERS OF HARDENED STEEL CORE FOR FAILURE MODELS
The complex material behavior of hardened steel projectile cores in impact scenarios places high demands on constitutive modeling. To measure material parameters for failure models, miniaturized round tensile, flat tensile, compression and compressiontorsion specimens were produced and quasi-static characterization tests were carried out on a material testing system machine. The specimens were made directly from the projectile cores of 14.5 mm caliber AP ammunition, which severely limited the maximum feasible specimen sizes. By using specimens with different geometries and notch radii, failure of the specimens was initiated at different multiaxial stress states. The compression-torsion specimen was used to generate different combinations of stress triaxialities and Lode angles at failure by setting different ratios of torsional to compressive loads. The specific stress states were determined by accompanying numerical simulations. It was exemplarily demonstrated that the measurement results can be used to improve the simulated fragmentation of a B-32 projectile core in a ballistic scenario.
EXPERIMENTAL AND NUMERICAL STUDY OF THE INTERACTION BETWEEN A SHAPED CHARGE JET AND A SINGLE ERA MOVING PLATE
An analysis of the interaction mechanisms between a Shaped Charge Jet (SCJ) and a single Moving Plate (MP) is proposed in this article using both experimental and numerical approaches. Both Backward Moving Plate (BMP) and Forward Moving Plate (FMP) collisions with a SCJ were tested with an experimental set-up presented in this article. A methodology, adapting the virtual origin approximation, is also proposed to analyze in detail the experimental results, extracting some comparative data. ???? simulations complete the analysis. The proposed explanation for the development of different interaction regimes is that the SCJ/MP interaction is driven at first order by the contact geometry. In the collision point frame of reference, the BMP flows in the same direction as the jet, causing its overall deflection. On the contrary, the FMP flow opposes that of the jet leading to an alternative creation of fragments and ligaments.
CHALLENGES IN HYDROCODE MODELING OF PROJECTILE IMPACT ONTO CERAMIC ARMOR IN A VELOCITY REGIME COMPRISING INTERFACE DEFEAT, PARTIAL DWELL, AND FULL PENETRATION
In the context of long rod impact against ceramic targets, the range of impact velocities from about 400 m/s to 1900 m/s covers cases of full and partial dwell as well as of immediate penetration, posing challenges in the accurate description by a unified numerical simulation model capable of predicting dwell times, residual penetration depths, and the fragmentation of the ceramics. In this work, through systematic comparison with a large set of impact data from prior experimental work on tungsten heavy alloy long-rod penetrators impacting onto unconfined silicon carbide ceramic tiles backed by rolled homogeneous armor, hydrocode simulations are exploited to assess the gaps in the characterization and modeling of ceramic materials and in the numerical approaches for the description of the projectile-target interaction. The different phenomena to be described demand competing modeling solutions and an attempt of their combination in a unified simulation approach with a commercial code is here tested and discussed.
INFLUENCE OF SHAPED CHARGE JET STATE ON ITS INTERACTION WITH ERA FLYING PLATE
When stretching, a Shaped Charge Jet (SCJ) is systematically subject to instabilities that disturb its surface, creating necks along it. In this article, we focus on these jet surface disturbances and their consequences on the SCJ interaction with an ERA moving plate. An experimental set-up was built to implement this interaction for different collision points, at different stand-off distances. One of the main results is the visualization of a regime change in the interaction between a SCJ and a Backward Moving Plate (BMP). A regime of deflection changes into a ligament regime interaction when the collision point stand-off is increased. This phenomenon is well captured by the ySPH simulations used to complete the phenomena analysis. Using both experimental and numerical approaches, we highlight that surface disturbances of the SCJ have a major influence on its interaction with a moving plate. Finally other simulations are performed to investigate the influence of both disturbance wavelengths and amplitudes on the interaction regimes.
MODELING OF SCHUBERTH HELMET UNDER BALLISTIC IMPACT FOR HEAD INJURY ASSESSMENT
A finite element model is developed to simulate the ballistic performance of the Schuberth helmet under 9x19 mm FMJ (Full Metal Jacket) bullet impact. The Schuberth helmet is a poly-aramid composite helmet, manufactured by Schuberth, formerly used by the Belgian Army as personal protection equipment. The model is validated on the basis of experimental data obtained during tests carried out within the Department of Weapon Systems and Ballistics (ABAL) of the Royal military Academy (RMA) using helmets of the same size at four different locations (front, left and right and crown). The metrics used for the model validation are the maximum Back Face Deflection (BFD) and the deflection time curves corresponding to the helmet back face dynamics. The Digital Image Correlation (DIC) technique is used for this purpose. Results show good agreement between numerical and experimental data. The validated model is then applied to simulate ballistic impacts on the Schuberth helmet mounted on an in-house head finite element head model to further investigate the risk of Behind Helmet Blunt Trauma.
CAPTURING NON-FMJ BULLETS FOR FORENSIC COMPARATIVE EXAMINATION—EXPERIMENTAL AND NUMERICAL STUDY
In the paper the research works on elaboration of novel solution for stopping without deformation wide range of non-Full Metal Jacket bullets is presented. The results which prove its effectiveness were shown. The paper describes the experimental tests and the numerical simulations of bullet impact into water, with nominal velocity. The critical value of impact velocity Vcr (which do not cause deformation of bullet) was found numerically. The composite reducing bullet velocity to Vcr was prepared and tested. With the use of the composite and plasticine a monolithic hollow point 9 mm GECO Action Extreme bullet was decelerated and slowly stopped in such a manner which not to cause bullet deformation. Proposed method could therefore be used to capture non Full Metal Jacket bullets in a form allowing determination whether the given weapon e.g. was used to fire a projectile found at the crime scene.
CANDLE GEL AS A REUSABLE ALTERNATIVE TO BALLISTIC GELATIN IN WOUND BALLISTICS RESEARCH
This study investigates the dynamics of temporary cavity formation in wound ballistics, comparing traditional Ballistic gelatin with Candle gel as a tissue simulant. While Ballistic Gelatin is labor-intensive, costly, and inconsistent, Candle Gel offers a more practical and cost-effective alternative due to its ability to be remelted and reused, ensuring consistent testing and better material control. The research examines how different calibers of projectiles affect cavity expansion and deformation, using high-speed cameras to measure these dynamics. Results highlight differences in cavity formation between gelatin and Candle Gel, with variations depending on projectile size, shape, and energy transfer. These findings offer valuable insights into the effects of material composition on ballistic trauma, contributing to more accurate tissue simulants for medical, forensic, and defense applications.
BALLISTIC TESTS OF Ti64 PLATES USING ARMOR PIERCING AMMUNITION WITH FLAT-NOSE HARDENED STEEL CORE
The paper continues the works previous works and presents the results of ballistic tests conducted on Ti-6Al-4V (Ti64) plates using 7.62×51 mm AP projectiles with flat-nose hardened steel cores. The tests were performed for two plate thicknesses (10 mm and 14 mm), allowing for an assessment of residual velocity using an ultra-high-speed camera and a comparison with literature data on point-nose core AP bullets. Based on observations, it can be noted that the impact velocity corresponding to the nominal parameters of the applied ammunition is close to the ballistic limit of the 14 mm thick plates. This result is consistent with our previous findings. To provide additional data for a more reliable verification of material models used in numerical simulations, further tests were required for thinner target plates.
INITIAL STUDY OF TERMINAL BALLISTIC EFFECTS FOR Ti-BASE MULTI-LAYERED TARGET CONSISTING OF METAL MATRIX COMPOSITE, POROUS TITANIUM, AND 3D-PRINTED Ti-6Al-4V MATERIALS
The influence of the composition and structure of a multilayer titanium-based material on its behavior under impact testing conditions was studied. The material consisted of 4 consecutive layers of: i) metal matrix composite (MMC) based on Ti64 alloy (wt. % Al-4% V) reinforced with 40 vol % disperse TiC particles, ii) Ti64 alloy, iii) porous commercial purity titanium (about 60% pores), and iv) the bottom layer of Ti64 alloy. Layers of MMC and Ti64 alloy were deposited on a layer of porous Ti using an electron beam 3D printing method with wire as the feeding material. Overall density of the layered material was less than 3 g/cm3. An impact test performed with a 7.62 mm caliber armor-piercing cartridge (with a bullet kinetic energy of 3430 J) demonstrated high ballistic resistance.
DEVELOPMENT OF THE SINGLE ANALYTICAL FORMULATION FOR THE DEFORMABLE PROJECTILE IMPACT ON THE MULTI-LAYER COMPOSITE
This study investigates the development of an analytical formulation aimed at predicting the depth of penetration when a deformable projectile impacts a multi-layer composite structure. The projectile, measuring 50.80 mm in diameter and 355.60 mm in length, is impacted against a target with dimensions of 1000 mm × 1000 mm and a thickness of 410 mm. The composite target comprises a soil layer, a boulder layer, a steel layer, a high-density polyethylene (HDPE) layer, and a reinforced concrete (RCC) slab layer. The formulation in this study starts by analyzing the penetration of a non-deformable projectile into a multi-layer composite and comparing the results with a monolayer boulder of equivalent thickness. This comparison is then extended to the case of a deformable projectile. To account for the deformation of the projectile nose, detailed numerical simulations are carried out for both the multi-layer composite and the monolayer boulder, allowing for an understanding of the impact of projectile deformation. These simulations lead to the development of a nose erosion factor that accounts for the nose deformation of the projectile. Based on the results from both the multi-layer composite and the monolayer boulder, it is concluded that the analytical formulation accurately predicts the depth of penetration in both cases. As a result, it is possible to use the simpler single-material analytical formulation to predict the behavior of multimaterial, multi-layer composites. This approach simplifies the process, reducing the need for complex and time-consuming mathematical calculations, and minimizes the risk of human error due to the involvement of numerous equations.
USING HYDROCODE SIMULATIONS IN NATURAL FRAGMENTATION ANALYSIS
This paper discusses the integration of hydrocode analysis into the Fragment Analysis Software (FAST) to improve the accuracy of fragmentation studies. FAST traditionally uses the Gurney method and Mott distribution to model and analyze fragmenting munitions. This study investigates replacing the Gurney method with a hydrocode for increased accuracy. The study uses experimental data from the 30 mm Gryazev-Shipunov GSh-30-1 autocannon and the SPEED software package for hydrocode analysis. The results show that incorporating hydrocode analysis improves the accuracy of velocity profile and natural fragmentation analysis. The hydrocode-based velocity profiles provide more accurate velocity distributions, leading to better fragment mass distribution predictions, especially for smaller fragments. While the Gurney model is useful for rapid assessments due to its low computational cost, hydrocode simulations offer a superior approach for high-fidelity analyses.
OPTIMAL TWO-STAGE BAYESIAN DESIGN FOR PENETRATION LIMIT VELOCITY TESTING
Quantile estimation (QE), also called sensitivity testing, is used in many fields of study. Ballistic performance metrics known as limit velocities (V50, V90, etc.) are estimated via QE. A popular QE method for finding said limit velocities is logistic regression. To perform the regression, the experimentalist must determine a set of test impact velocities, known as the experiment’s “design”. Many of the leading design methods used in small arms limit velocity tests are “sequential” in that the mth test velocity is determined by the previous m − 1 test results. Although these designs are typically more optimal from a statistical perspective, they are often impractical. This paper seeks to balance statistical optimality and practical considerations by proposing a two-stage logistic regression design method so that test velocities only need to be set twice during the experiment. While developed for limit velocity testing, this two-stage approach can be used to design any experiment using logistic regression QE.
TEMPERATURE EFFECT ON THE BALLISTIC PERFORMANCE OF MILD STEEL PLATE: A NUMERICAL STUDY
This paper numerically investigates the effect of a rigid projectile on the behavior of mild steel plate at different initial temperatures using ABAQUS/Explicit. Additionally, efficacy of the thickness of the plate on ballistic performance at higher temperature is studied. Initial plate temperature in the range of 27 °C to 1500 °C is used. The results show that the residual velocity increases as the initial plate temperature increases and is nearly linear up to 500 °C and, after that, tends to become constant. Temperature rise is insignificant for the initial plate temperature range of 27 °C to 400 °C but exceeds 1000 °C for temperature from 400 °C to 900 °C. No significant temperature rise is observed for initial temperature exceeding 900 °C. Failure modes of steel plate is also studied and discussed. Secondly, effectiveness of increasing plate thickness on ballistic performance of steel plate at higher temperature is studied and discussed.
TWO-DIMENSIONAL AND THREE-DIMENSIONAL STRUCTURED ARBITRARY LAGRANGIAN-EULERIAN (S-ALE) METHODOLOGIES FOR THE ANALYSIS OF SHAPED CHARGE PENETRATION
This paper presents a novel simulation method developed to address Shaped Charge Penetration (SCP) phenomena, focusing on high strain rate deformations occurring during both the formation of the shaped charge and its subsequent penetration into targets. A Structured Arbitrary Lagrangian-Eulerian (S-ALE) framework was employed to accurately model dynamic interactions and material responses involved in these processes. A series of simulations was performed across a range of parameters, enabling a comprehensive analysis of the shaped charge’s behavior under varying conditions. Specifically, the study examined the BRL-82 munition, utilizing both two-dimensional (2D) and three-dimensional (3D) simulation approaches to assess the impact of dimensionality on penetration effectiveness and charge performance. To validate the numerical model, comparisons were made with empirical test data from established literature, confirming the accuracy and reliability of the proposed method. The findings demonstrate that the simulation method reliably predicts penetration outcomes and enhances the understanding of shaped charge dynamics.1
UNRAVELING IMPACT DYANMICS: A NUMERICAL STUDY OF CONICAL AND BLUNT PROJECTILE PENETRATION IN THIN ALUMINUM PLATES
This study numerically investigates the impact behavior of conical and blunt projectiles on thin aluminum 2024-T3 plates using ABAQUS. Simulations analyze a 0.82 mm thick plate impacted at velocities from 28 to 100 m/s. Results reveal distinct penetration behaviors: the conical projectile exhibits a four-petal failure mode and penetrates at a lower ballistic limit (28.57 m/s), while the blunt projectile requires higher velocity (50.44 m/s) and forms a single plug. Variations in residual velocity, absorbed energy, damage energy, and impact duration highlight the influence of projectile geometry. Sensitivity analysis demonstrates how variations in material properties and friction significantly affect ballistic outcomes. These findings provide insights into impact resistance and structural response, aiding in protective material design. Future studies should refine material models and explore broader impact conditions.
AN EXPERIMENTAL AND FEM BASED APPROACH TO ASSESS BASALT/KEVLAR HYBRID LAMINATES FOR BALLISTIC PROTECTION APPLICATIONS
This research investigates the ballistic performance of Basalt/Kevlar hybrid laminates against Fragment Simulating Projectile (FSP) impacts using both experimental testing and finite element modeling (FEM). The study compared various configurations of 12-layer laminates, including pure basalt fiber reinforced composites (BFRC), pure Kevlar fiber reinforced composites (KFRC), and hybrid combinations. The 6/6 basalt-Kevlar configuration, particularly with basalt as the strike face, demonstrated superior performance, achieving a 30- 40% reduction in projectile velocity and 40% increase in energy absorption compared to single-material laminates. The enhanced performance is attributed to the complementary properties of both materials: basalt's higher compressive strength for initial projectile deformation and Kevlar's superior energy absorption capabilities. FEM simulations were validated through experimental testing with less than 10% error margin, and damage patterns were analyzed using infrared thermography. The findings suggest that these hybrid laminates offer promising solutions for advanced ballistic protection applications.
ANALYTICAL MODEL FOR HEAD RESPONSE WITH HELMET UNDER BALLISTIC IMPACT
In order to improve the understanding of the injury mechanism under blunt impact, and to make up for the deficiencies of experiments and numerical simulations in terms of computational efficiency and mechanism analysis, the head with helmet was simplified into a liquid-filled multilayer spherical shell structure with a hemispherical shell. Corresponding to the anatomical features of the skull, brain tissue, soft meninge, and hard meninge, analytical model of the response of head with helmet under ballistic impact load was established based on contact deformation and kinematics theory, and compared with public linear and nonlinear blunt impact head models for verification. Based on the analytical model, the head response under the influence of factors such as ballistic impact velocity and helmet weight were obtained. Combined with head injury criteria (HIC), the risk of head injury under ballistic impact was predicted, providing a theoretical basis for helmet improvement and injury evaluation after protection.
DETONATION CHAMBER FOR END OF LIFE WARHEADS DISPOSAL IN FULLY CONFINED CONDITIONS: FROM DESIGN TO PROOF TESTS
This paper deals with the design and proof tests of a 60kg NEQ TNT detonation chamber dedicated to end of life warhead disposal in a fully confined environment. This chamber, is intended to replace open air, semi-confined temporary setup structures [1], buried or undersea destructions. By this, it minimizes drastically the human footprint on environment but also decreases safety distances when dismantling because everything (blast and fragments) stay control and confine for easy post-treatments. The challenging steps followed to ensure chamber integrity are detailed to explain how they ensure dismantling of reformed and not transportable stockpile of missiles (warhead and propellant). This work illustrates the methodology used and results obtained. The first part reminds the various steps followed to sustain blast and multi-fragments impacts from threat analysis to initial destruction [2][3]. The second part details how the inner protection shielding was optimized by numerical simulations after the first test.
EVALUATION AND COMPARISON OF BACKFACE DEFORMATION
The choice of backing material when performing evaluation testing on body armor materials is crucial. Different types of material produce different parameters that may be observed and studied. RP1 has been the standard backing clay used in ballistic armor testing since its implementation in the 1970s. Due to formulation changes and its need to be temperature controlled, those in the ballistic community began investigating new materials. This led the Army Research Laboratory to create a new temperature-insensitive silicone composite clay material. This study observed the ballistic impact of both the silicone composite and RP1 using three threat levels (HG1, HG2, and RF1) as stated by the National Institute of Justice. It was found that both clay types responded similarly in the lower threat levels, however further testing is needed to understand the differences in the higher threat levels.
BALLISTIC LIMIT EVALUATION OF A 5 MM STEEL PLATE AGAINST FRAGMENT SIMULATING PROJECTILE USING SINGLE STAGE PROPELLANT GUN
Steel Plate is used for protection against fragments in auxiliary units of the armament system. The Ballistic Limit (BL) of the protection plate must be evaluated. This study evaluated a 5 mm steel plate for its BL against a 0.22’ calibre Fragment Simulating Projectile (FSP) using a smooth bore single-stage propellant gun of 30 mm Caliber with the support of Nylon Sabot. The velocity of the fragment was varied by adjusting the charge mass of the propellant (NC 1140) from 18 to 28.75 g to get a velocity from 600 m/s to 933 m/s. IR-based velocity screens were used to measure the projectile striking and residual velocity for pre and post-impact respectively. The target material was 1.0421 ST-52 Grade Steel, which is low-carbon manganese steel with good impact resistance. The projectile material was AISI 4340 Steel of Rockwell Hardness 30 ± 1 HRC. The FSP was recovered and the residual mass of the fragment was measured. It was concluded that there was negligible change in the mass of the recovered fragment. Therefore, the Recht-Ipson (RI) model of ballistic limit estimation is applied to evaluate the Ballistic Limit of the plate. In addition to this, V50 ballistic limit was also computed which is a statistical approach. It is observed that the V50 Ballistic limit for the target-projectile combination is 862 m/s approximately, whereas the RI model predicts a slightly higher ballistic limit.1
PRELIMINARY INVESTIGATION OF CYLINDRICAL BUBBLE MODELS FOR CONFINED CAVITY INDUCED BY HYDRODYNAMIC RAM
Hydrodynamic ram (HRAM) phenomena, triggered by high-velocity projectiles impacting water-filled containers, induce confined cavities whose evolution is strongly influenced by container constraints. This study integrates experimental data, numerical simulations using LS-DYNA’s ALE method, and theoretical models—including a model developed by the authors (Ji model) and both incompressible and compressible cylindrical bubble models— to investigate cavity evolution. While simulations accurately capture the initial expansion phase, they underestimate contraction dynamics. Theoretical analysis reveals that, under a specific energy condition, the Ji and incompressible cylindrical bubble models yield equivalent predictions, and the compressible model shows superior agreement with experiments compared to its incompressible counterpart. These results emphasize the critical role of initial conditions and pressure parameters in modeling confined cavities and provide quantitative insights into the asymmetrical expansion and contraction phases observed experimentally.
EFFECTS OF WELDING PARAMETERS ON THERMAL CHARACTERISTICS IN WELDED JOINTS OF ULTRA-HIGH HARDNESS ARMOUR STEELS
This study examines the influence of welding parameters on the thermal cycle of the welding process—specifically, heat input, cooling time, and average cooling rate—in welded joints of ultra-high-hardness quenched and tempered (UHH-Q&T) armoured steel. Preliminary experiments were conducted to establish fixed parameters for the main tests, including gas flow rate, welding voltage, wire diameter, and wire feed speed, based on the technological capabilities of the welding equipment. The primary experiments utilized the conventional gas metal arc welding (GMAW) process, in which welding speed and stick-out were varied according to a full factorial design, while the current remained constant. The key thermal cycle variables of the welded joints were determined using theoretical heat flux equations, validated through dilatometry test simulations. These simulations were further assessed by comparing the microstructural characterization and microhardness mapping of real and simulated heat-affected zone (HAZ) subzones.12
EFFECT OF THE PROJECTILE IMPACT POSITION ON THE BALLISTIC EFFICIENCY OF THE COMPOSITE ARMOUR
The extensive numerical simulations of the ballistic efficiency of the armours against to the projectile 14.5 mm x 114 API/B32 were performed. The armours were made from the add-on ceramic armour composed from alumina ceramic pellets on a layer of aramid laminate placed on UHSLA steel plate base armour. The projectile striking velocity was chosen to be 911 m/s. The effect of impact position and effect of adhesive properties were investigated. The numerical simulation was performed for both single impact and multihit. Result of numerical simulation were compared with real terminal ballistic experiments.
NUMERICAL SIMULATION OF DIAMOND FRAGMENT PENETRATING BALLISTIC GELATIN
Experiment and computation study on the penetration of rhombic fragments into a block of ballistic gelatin is performed for improving our understanding the wound mechanism. The temporary cavity size and tumbling degree of fragments in ballistic gelatin was quantified to describe the behavior of the fragments impact gelatin. During rhombic fragments penetrating ballistic gelatin, four stages were clearly observed in both the experiment and the numerical simulation: a smooth attenuation stage, a rolling stage, a quasi steady penetration stage, stopping penetration stage and a stage of expansion and contraction.. Moreover, the effects of the fragment’s impact velocities and angles of incidence on the temporary cavity in gelatin were investigated, as well as the fragment’s resistance and energy variation. Thus, the physical process and the interactive mechanism during a rhombic fragments penetrating gelatin were comprehensively revealed. This may be significant for research in wound ballistics.
STUDY ON THE INFLUENCE OF ADHESIVE ON THE ANTI-PENETRATION PERFORMANCE OF CERAMIC-METAL LAMINATED PROTECTION
The application of ceramic and multi-layer composite structures of other materials in individual soldier protective equipment has improved the survivability of soldiers on the battlefield. The requirements of the new generation of individual soldier protective equipment are to ensure protection and light weight simultaneously. In this study, Ls- Dyna simulation software was used, and the FEM-SPH coupling algorithm was adopted. A numerical model of 7.62 mm armor piercing projectile penetrating ceramic laminated protection was established. The accuracy of the ceramic material parameters was verified by the residual penetration and penetration tests of Si3N4 ceramics, and the simulation results of the projectile penetrating the laminated structure were compared with the test results. It was found that the numerical simulation results were close to the ballistic test data; the maximum error of the data was less than 8%, and the effectiveness of the model was verified. The ceramic lamination protection of projectile penetration with different binders and the ceramic structure of projectile penetration with two types of binders were studied. The influence of the binder material on the protection performance was studied. The protection performance of the epoxy resin-bonded laminated protective structure was superior to that of the metal silicone-bonded laminated protective structure.
EVALUATION OF THE RESIDUAL PENETRATION CAPABILITY OF RIFLE PROJECTILES ON TARGETS BEHIND MASONARY BASED ON EXPERIMENTS
To evaluate the residual penetration capability, an evaluation of the post-penetration residual penetration ability of seven typical projectiles through masonry is conducted. An evaluation index system structure model, encompassing power, ballistic performance, and shooting accuracy, is established. Utilizing test data, the index weight coefficients are ascertained through the grey comprehensive analysis method, and the final ranking is derived from a comprehensive evaluation using the grey weighted correlation degree. The findings indicate that this approach is viable, and the evaluation results for the residual penetration ability of seven rifle projectiles after penetrating masonry (autoclaved aerated concrete block,3.5MPa) are as follows:7.62x54 R armor-piercing incendiary projectiles > small-caliber armorpiercing projectiles >7.62x51 armor-piercing projectiles >7.62x51 ordinary projectiles > small-caliber ordinary projectiles >5.56 mm armor-piercing projectiles >7.62x54 R ordinary projectiles. This methodology offers an innovative approach for evaluating the combat effectiveness of rifle projectiles against targets located behind masonry, and it serves as a reference for the combat effectiveness evaluation and design of rifle projectiles.
NUMERICAL SIMULATION OF RIFLE BULLET PENETRATION INTO HOLLOW CONCRETE BLOCKS USING A FAILED NODE-TO-SPH ALGORITHM
In order to reveal the motion law of rifle projectile penetration into hollow blocks, the failure-node-to-SPH (Smoothed Particle Hydrodynamics) algorithm was applied to numerically simulate the process of rifle projectile penetration into the block. High-speed photography was used in experiments to obtain data on the projectile's impact velocity, residual velocity, post-impact motion attitude, and damage to the target. By comparing with experimental data and typical physical phenomena, the numerical method was able to reproduce the projectile's behavior within the block. The results indicate that the failurenode- to-SPH algorithm effectively demonstrates the block fragmentation and scattering phenomenon, with the exit damage pattern almost identical to the experimental results. Furthermore, the projectile penetration process can be viewed as the penetration of a twolayer concrete target with a thin spaced target plate. The number of velocity changes and the peak overload values correspond to the equivalent number of layers. The deflection of the projectile upon exiting the target mainly arises from the attack angle generated before the projectile penetrates the second layer of the target. The residual velocity and overload values are positively correlated with the impact velocity, while the deflection amplitude at the moment of exit is negatively correlated with the impact velocity. The research findings provide a basis for enhancing the capability of small arms to penetrate brick-wall-protected personnel targets.
EXPERIMENTAL STUDY ON THE INFLUENCE OF GLASS THICKNESS ON THE POST-PERFORATION KINEMATICS OF MONOLITHIC COPPER PROJECTILES
To investigate the motion characteristics of projectiles post-perforation glass targets of varying thicknesses, this study employed monolithic copper projectiles with a ballistic coefficient of 1.03 to perforate standard soda-lime glass plates of 3 mm, 5 mm, and 10 mm thickness. High-speed imaging techniques were utilized to capture the post-perforation motion dynamics, while velocity measurement systems recorded impact velocities, and soft recovery methods enabled projectile retrieval. Time-dependent curves for centroid displacement, yaw angle, and angular variations were derived from the imaging data and projectile measurements. Statistical analysis of multi-test averages revealed preliminary conclusions validating the experimental methodology. Polynomial relationships were established to characterize centroid displacement, yaw angle, and angular rate over time. Quantitative analysis demonstrated positive correlations between glass thickness and projectile length loss, mass loss, velocity reduction, and kinetic energy dissipation. These findings provide critical insights for the design of specialized ammunition optimized for glass barrier penetration scenarios.
RESEARCH ON THE TEST OF BEHIND ARMOR BLUNT TRAUMA BASED ON ARTIFICIAL THORAX
Testing the blunt impact effects of projectiles behind body armor is an effective method for investigating the mechanisms of behind armor blunt trauma. In this paper, the PVDF pressure sensors were selected and installed within the various tissues and organs of the artificial thorax and the testing system was established by data acquisition device. The artificial thorax equipped with body armor was impacted by the 9mm caliber pistol projectile with an initial velocity of 360m/s and obtained the pressure values of tissues or organs from the embedded sensors inside the artificial thorax. Simultaneously compared the dynamic responses of the sternum, heart and lung inside the artificial thorax. The results showed that the pressure value on surface of the skin was the highest and averaging approximately 900kPa, followed by the sternum at an average of 600kPa, which indicating that the sternum withstood the stress caused by deformation and compression of skin. The internal organs were subjected to varying degrees stress of blunt trauma and the heart enduring relatively higher pressure. This study could reveal the mechanism of behind armor blunt trauma and provide guidance for improving the protective capabilities of body armor and the diagnosis and treatment of blunt trauma.
IMPACT OF CERAMIC-METAL-PE TARGET PLATE STRUCTURE AND INTERFACE PROPERTIES ON DEFENSE AGAINST ADVANCED CEMENTED CARBIDE PROJECTILES
Traditional ballistic armor systems face significant challenges in defending against advanced hard alloy projectiles. This study explores the performance of ceramic-metalultra-high molecular weight polyethylene (UHMWPE) composite armor through numerical simulations. Results reveal that boron carbide (B4C) ceramics, due to their exceptional hardness, low density, and energy absorption efficiency, significantly outperform silicon carbide (SiC) in resisting hard alloy penetration. A composite structure consisting of 10 mm B4C, 1 mm titanium alloy, and 8 mm UHMWPE provides effective protection. However, reducing the ceramic thickness to 9 mm and increasing the titanium alloy thickness to 2 mm leads to a notable performance decline, despite higher areal density. Additionally, the interfacial bonding strength between ceramic and metal layers is crucial: increasing it from 10 MPa to above 30 MPa enhances defensive capability, with 90 MPa offering optimal protection. This research provides critical insights and practical guidelines for designing high-performance ballistic armor systems.
RESEARCH ON KEY PROTECTIVE AREAS OF THE HUMAN HEAD AGAINST BLAST WAVES
This study focuses on identifying key protective areas of the human head to improve the effectiveness of head protection against blast waves. A three-dimensional finite element model with a typical human head structure was established, and numerical simulations were conducted to study the effects of blast waves on the head. The mechanical propagation pathways of pressure responses in brain tissues caused by blast waves were obtained. The main affected areas of brain tissue pressure responses under blast wave were identified by controlling the propagation paths of blast waves on the face. This study determines the key areas of the head that should be protected in explosive environments, providing guidance for the design of enhanced blast wave protective helmets.
RESEARCH ON THE IMPACT OF HEAD-LINER GAP SIZE ON BLAST WAVE PROTECTION EFFECTIVENESS
This study investigates the impact of the head-liner gap size on blast wave protection effectiveness based on a ring-shaped liner. A finite element model of the head with a typical cranial structure was established and subjected to blast wave loading. The head model was equipped with a protective helmet, and a sealing liner was designed inside the helmet. This liner circumferentially surrounds the head, effectively preventing the blast wave from entering the head-helmet gap and providing protection to the head. By varying the dimensions of the ring-shaped liner, different head-liner gap sizes were achieved, and the impact of the gap on the helmet's protective capability was studied. The results show that the attenuation of the blast wave peak overpressure by the helmet is approximately linearly related to the head-liner gap size. The larger the gap size, the lower the attenuation of the blast wave overpressure by the helmet, and the worse the helmet's blast wave protection capability. Therefore, while ensuring the comfort and breathability of the helmet, the headliner gap size should be minimized to enhance the helmet's blast wave protection capability.
MODELING THE FORMATION AND PENETRATION OF A HIGH-SPEED JETTING PROJECTILE CHARGE
In this study, experiments and numerical analyses have been carried out to investigate the performance of a modified high-speed Jetting Projectile Charge (JPC) based on a Explosively Formed Projectile (EFP). A medium-carbon steel (AISI 1045) target was used in the penetration experiments of the modified JPC and the conventional EFP. The tip velocity of the metal jet before penetration was measured using speed sensors. The length to diameter ratio of The EFP is 1:1, the shell thickness is 5 mm, and the linear thickness is 1.8mm. The formation and penetration performance of the modified shaped charge structure were reproduced in a validated numerical simulation using AutoDYN-2D. The penetration depth, the diameter of the penetration crater, and the tip velocity of the JPC/EFP obtained from the simulation agreed well with the experimental results. The function of the propelled structure, the auxiliary structure, and the liner of the modified JPC and their interactions with each other were discussed and compared with the performance of the JPC in terms of the shape\velocity of the jet and its penetration ability by numerical simulation. Both the experiments and numerical simulations shows that the penetration depth of the modified JPC into the mild carbon steel (AISI 1045) increased by 55 % compared to that of the EFP.
EXPERIMENTAL RESEARCH ON THE BLUNT IMPACT EQUIVALENCE OF LUNG—SIMULATING MATERIALS
In order to build a set of lung simulating surrogate with similar mechanical properties and equivalent blunt impact effect, a one-dimensional pressure wave transmission device is proposed in this paper. Through this device, the changes of pressure and pressure impulse of biological lung tissue and lung simulating materials under blunt impact are verified. The overpressure peak and the attenuation rate of pressure impulse are used as physical parameters to verify the blunt impact equivalence of the two materials, and the blunt impact equivalence of biological lung tissue and lung simulating material is verified. The test data show that the overpressure peak and pressure impulse attenuation of pressure wave are less than 5% in the pressure transmission range of 100kPa - 400kPa, which proves the stability and testability of the device. The attenuation deviation of overpressure value and pressure impulse between the selected lung simulating material and biological lung tissue is 14.78% and 5.16%, which verifies the blunt impact equivalence between the lung simulating material and biological lung tissue. The testing method of this device can provide a new testing method for the subsequent mechanical properties research of biological soft tissues and soft materials.
EXPERIMENTAL STUDY ON LUNG SURROGATE BY BLUNT IMPACTING OF RUBBER BULLET
To construct a lung surrogate with similar mechanical properties and equivalent blunt impact effects, foam silicone material was used as a simulated biological lung material. The material was processed into lung organs structurally resembling biological lungs and integrated with sensors, data acquisition devices, and other equipment to build a testable lung surrogate. Experimental results demonstrated that the mechanical compression properties of the lung surrogate closely matched those of biological lungs, with strong consistency in compression force and compression rate test outcomes. Under the blunt impact of rubber bullets, the deviation in surface peak overpressure attenuation between the lung surrogate and biological lung was 0.23%, while the deviation in overall lung pressure impulse attenuation was 0.16%. The lung surrogate and testing methodology provide technical support for subsequent assessments of lung blunt impact trauma and evaluations of thoracic protective equipment.