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A method for intermediate ballistics modelling is presented. The method is used to study the effect of muzzle brakes with a passing projectile. Pressures, velocities and impulses are computed using a thermodynamic interior ballistics code (lumped parameter code) for projectile travel within the barrel. Then Computational Fluid Dynamics (CFD) simulations are used for gas and projectile travel outside the barrel. CFD simulations are performed both with and without a projectile and the results compared. Three generic muzzle brake geometries are used for simulations. Impulses computed from thermodynamic model and CFD model are combined to evaluate the gun recoil. The CFD model, with initial conditions transferred from the thermodynamic model, can further be used to analyse the influence from the muzzle break on the flow.

Instead of the capillary plasma generator (CPG), a discharge rod plasma generator (DRPG) is used in the 30 mm electrothermal-chemical (ETC) gun to improve the ignition uniformity of the solid propellant. An axisymmetric two-dimensional interior ballistics model of the solid propellant ETC gun (2D-IB-SPETCG) is presented to describe the process of the ETC launch. Both calculated pressure and projectile muzzle velocity accord well with the experimental results. The feasibility of the 2D-IB-SPETCG model is proved. Depending on the experimental data and initial parameters, detailed distribution of the ballistics parameters can be simulated. With the distribution of pressure and temperature of the gas phase and the propellant, the influence of plasma during the ignition process can be analyzed. Because of the radial flowing plasma, the propellant in the area of the DRPG is ignited within 0.01 ms, while all propellant in the chamber is ignited within 0.09 ms. The radial ignition delay time is much less than the axial delay time. During the ignition process, the radial pressure difference is less than 5 MPa at the place 0.025 m away from the breech. The radial ignition uniformity is proved. The temperature of the gas increases from several thousand K (conventional ignition) to several ten thousand K (plasma ignition). Compare the distribution of the density and temperature of the gas, we know that low density and high temperature gas appears near the exits of the DRPG, while high density and low temperature gas appears at the wall near the breech. The simulation of the 2D-IB-SPETCG model is an effective way to investigate the interior ballistics process of the ETC launch. The 2D-IB-SPETC model can be used for prediction and improvement of experiments.

This paper presents high speed video analysis of 11 service caliber lead-free pistol bullets impacting Clear Ballistics Gel® with the dual purpose of assessing the equivalence of Clear Ballistics Gel® and calibrated 10% ballistic gelatin as test media and providing an initial assessment of wounding and incapacitation potential of these 11 service caliber loads. The present study suggests that Clear Ballistics Gel® results in lower retarding forces, erratic expansion, greater variations in penetration depth, and larger average penetration depths than calibrated 10% gelatin. Taken together with other results, testing in Clear Ballistics Gel® should only be used to identify candidates for further testing in calibrated 10% ballistic gelatin; it should not be used for the selection of duty ammunition without further performance testing in calibrated 10% ballistic gelatin. Depending on the wound profile and penetration desired for a given application, several loads analyzed here may warrant additional study. The Liberty Civil Defense 60 grain lead-free hollow point had the largest peak retarding force, temporary cavity, and permanent cavity while meeting the oft-cited minimum penetration requirement of30 cm.

The main objective of this work is to assess the pressure levels obtained over a new designed 155 mm/52-calibre gun-howitzer during a firing sequence. For this design, the barrel muzzle exit is really close to the truck driver’s cab. It is then essential to verify that the wall pressure levels resulting from an artillery firing are compatible with the considered material. For this purpose, the CFD ballistics code FREIN 3D is used to compute the direct coupling between interior, intermediate and exterior ballistics of this new 155 mm/52- calibre gun-howitzer. A simplified geometry is considered for the CFD computation and the computational domain involves only a part of the truck chassis since only the pressure levels over the first part of the truck are of interest. One case is considered, corresponding to an indirect firing.

Small caliber interior ballistic performance can be altered in countless ways. Primer composition, propellant composition and quantity, as well as the interaction between the two play a critical role in determining a cartridge’s performance. This study will focus on the interaction between the primer products and the ignition of the propellant of a 7.62- mm cartridge. To accomplish this a flash tube will be employed to alter the ignition characteristics of the propellant. By employing a flash tube the primer products will be directed into the case at a more forward location in the propellant bed thus altering the ignition and subsequent burning characterization of the propellant. Various length and diameter flash tube configurations will be explored to characterize how the ignition of the propellant influences the interior ballistics of the cartridge.

Aiming at the object of the firing range maximization of the grenade of the cased telescoped ammunition(CTA) gun, a classical interior model was established according to the special charge structure of the CTA and the principle of the sequential combustion with two ignitions. Combined with the particle trajectory model, the optimization design of the integration of the interior and exterior ballistics was carried out using the intelligent optimization algorithm. The results show that, the maximum chamber pressure and the muzzle velocity simulated using the interior model of the CTA gun agree well with the experimental results. The optimal scheme of the projectile mass and the charge design was obtained by means of the optimization design of the ballistic integration. The grenade projectile mass increases 16.4% and the maximum range increases 11.8% compared with the original scheme. The method in the paper can improve the integrated ballistic performance of the CTA and provide an efficient tool for its ballistic and charge design.

Several nations have moved to lead free bullets in 5.56x45mm NATO for use as duty ammunition by military personnel. This study reports on the external ballistics and accuracy of two lead free bullet designs that have been fielded to date, the 62 grain lead free hard core bullet manufactured by RUAG and the 62 grain lead free bullet manufactured by ATK at the Lake City Arsenal. Doppler RADAR was used to determine aerodynamic drag curves for each bullet from Mach 1.5 to Mach 3.0 when fired from rifles with twist rates of 1 in 7”, 1 in 8”, and 1 in 9”. Drag coefficients were consistent with claims by the manufacturers when fired from 1 in 7” and 1 in 8” twist barrels; however, drag coefficients varied up to 50% higher when fired from the 1 in 9” twist barrel, suggesting marginal stability. The 1 in 9” twist affects the drag of the ATK bullet more than the RUAG bullet. Accuracy of the RUAG bullet was less than 2 minutes of angle (MOA) when fired from a match grade rifle and less than 4 MOA when fired from a service grade rifle. However, accuracy of the ATK bullet was worse (2 MOA to 4 MOA) from the 1 in 7” twist match grade rifle and poor (6 MOA to 8 MOA) from a service grade rifle with 1 in 9” twist. The original Miller formula for gyroscopic stability of each bullet shows good agreement with experimental data. This formula may be used to estimate gyroscopic stability within 5% for a variety of twist rates, muzzle velocities, and atmospheric conditions.

The following article is a summary of the first step of research on behavior of sniper rifles in calibers .308 Winchester, .300 Winchester Magnum and .338 Lapua Magnum with and without sound suppressor. The paper includes measurements of chosen external ballistics parameters like velocity and accuracy at 300 m (328 yd) with the use of state of the art electronic devices like high speed accuracy light gates and Doppler radar system. The paper includes also a comparison of mentioned parameters registered during testing with two types of silencers and with unsuppressed weapon. The paper is concluded with results analysis that can be used for future work.

To improve the muzzle velocity by a large margin without increasing the gun chamber pressure, a lateral-injection for energy compensation technology was proposed. The principle is installing a regenerative auxiliary chamber with liquid propellant at a proper location in the barrel to compensate the energy in the space behind the projectile. Aiming at the interior ballistic characteristics of the technology, the corresponding model was established and the numerical simulation was carried out for a certain gun. Results show that the location of the auxiliary chamber, the injection area, the differential ratio and the mass of the injection piston have significant effects on the interior ballistic performance. By optimizing these parameters, the muzzle velocity can be increased substantially. The method can provide a new thought for designing the high-speed launcher.

An ordinary gun projectile will, after entry into water, be subject to an extremely high drag and will stop after 50 – 100 calibers of travel through the medium. To avoid such a response, supercavitation must take place. By a specially shaped projectile nose, the flow of water around the projectile may escape contact with the surface of the projectile, except at the nose tip. Under these conditions, the projectile is said to be supercavitating. In such a state, the projectile is unstable, but, the stability is maintained by the oscillation caused by the interaction between the rear part of the projectile and the cavity wall. In order to keep the amplitude of this oscillation as small as possible, the size of the cavity should be just slightly larger than the projectile. The cavity size is, however, determined by the size and shape of the nose tip, by the velocity of the projectile, and by the pressure in the ambient water (i.e. the water depth), through Garabedian’s equations. These parameters will also determine the duration of the cavity which determines how far the projectile will travel before the supercavitation ceases, and the projectile stops. The paper outlines the theory for the size, shape, and duration of the cavity. It discusses also the conditions for designing an optimal design of a supercavitating projectile. Special emphasize is put on how to determine the drag on the projectile by observing the size of the bubble.

Knowledge of impact conditions is critical to evaluating the terminal impact performance of a projectile. For a small caliber bullet, in-flight velocity has been precisely measured for decades using detection screens, but accurately quantifying the orientation of the bullet on a target has been more challenging. This report introduces the Automated Small-Arms Photogrammetry (ASAP) analysis method used to measure, model, and predict the orientation of a small caliber bullet before reaching an impact surface. ASAP uses advanced hardware developed by Sydor Technologies to record a series of infrared digital photographs. Individual images (four orthogonal pairs) are processed using computer vision algorithms to quantify the orientation of the projectile and re-project its precise position and orientation into a three-dimensional muzzle-fixed coordinate system. An epicyclic motion model is fit to the measured data, and the epicyclic motion is extrapolated to the target location. Analysis results are fairly immediate and may be reviewed during testing. Prove-out demonstrations have shown that the impact-angle prediction capability is less than six hundredths of a degree for the 5.56 mm ball round tested. Keywords: Yaw, Terminal ballistics, Exterior ballistics, Test & evaluation, Computer vision, Image processing, Angle of attack

In order to get the different muzzle velocity in large caliber artillery gun systems, the propellant charge usually have several charge zones. When these charge zones been fired, the different chamber pressure and projectile velocity will happen which can influence the burning rate of propellants. It is very important for getting the burning rate of propellants in different charge zone when predicted the performance of interior ballistics. Usually we can get the burning rate of propellant from experiment results of closed bomb, but these results cannot be directly used in numerical simulation of interior ballistics processes for all charge zones. Now, we use a serial experiment of gun firing for different charge zone to get the performance of interior ballistics. On the basis of the simulation for performance by the IB code, we can get the real burning rate of propellant in IB processes. By using the methods, we can get the accurate results for predict the interior ballistics performance when different charge zones were used. So in this paper, an approach has been developed for getting the real characteristic of burning rate of propellant at different charge zone for large caliber artillery gun systems.

This paper investigated the effect of mid-wall water cooling for the gun barrel under continuous firing. A 2D cross-section model of the gun barrel is adopted and the cooling channel is circular. An interior ballistics code is used to determine the inner wall convection boundary condition, providing gas temperature and heat transfer coefficient. Results of temperature histories of the inner wall and outer wall and temperature distributions are presented. The results show that this cooling method can slow down growth rate of the peak temperature of the inner wall.

Based on the research of large caliber modular charge howitzer and electrothermal-chemical (ETC) launch technology, the application advantages and prospects of ETC launch technology in a 155mm modular charge howitzer are discussed from the perspective of the technology development and actual applications, respectively. The analysis and discussion results show that the ETC launch technology will effectively improve the chamber combustion stability and interior ballistics consistency of the modular charge howitzer. It also will enhance the whole operational effectiveness including both firing range and accuracy. The ETC launch technology is an important development route for the future modular charge howitzer.

An optimization method is introduced to design the aerodynamic parameters of a dual-spin two-dimensional guided projectile with the canards for trajectory correction. The nose guidance kit contains two pairs of canards which can provide lift and despinning with a projectile for stability. An optimal design algorithm is developed to decide the profiles of the steering and spinning canards, and their deflection angles are also simulated to meet the needs of trajectory correction capabilities. Finally, the aerodynamic efficiency of the specific canards is discussed according to the CFD simulations. The simulation and analysis results can be further applied to the exterior ballistics design.

In the field of experimental small arms ballistics there has always been a large amount of energy put into how a test weapon is secured. Various philosophies exist; however, this is largely left to experience and is more of an artistic approach rather than a scientific approach. Many experimentalists leverage physical understanding of the firing event to reduce motion or vibration. However, in most cases, there is no direct measurement of the performance of the mounting technique. Often the dispersion performance of a weapon system when fired from a specific mount is used as a gauge, ignoring the fact that dispersion is comprised of many sources. Through complex jump testing, the US Army Research Laboratory has shown the ability to dissect the relative contribution of individual dispersion sources. This work showed that it is possible to mount a weapon system in a way that barrel motion does not affect the dispersion or jump behavior. This effort employs an easy-to-use modern measurement technique to characterize barrel motion of a commercial AR-15 weapon during dispersion testing. High speed digital micrometers were used to measure barrel motion before, during, and after firing in order to establish the pointing angle and crossing velocity variability as a function of mounting configuration. Ten mounting configurations were examined for a single weapon type firing match grade ammunition with the intention of isolating the barrel motion effects.

The science of “Internal Ballistics” have extensively studied the pressure generated within the cartridge and clearly indicate that maximum generated pressure (Peak Pressure) is not to exceed the yield strength of the material of which the cartridge case is made of [1]. Failure to ensure this could result in catastrophic accidents that may lead to death or serious injuries. Different test standards (SAAMI, C.I.P, MIL-STD and NATO EPVAT) were established to ensure the safety of the ammunition in terms of pressure. These standards differ in many aspects from the test procedure to the equipment used to the acceptance criteria. The main motive behind this study was understanding the need to establish a scientific correlation between pressure measurements obtained by different test standards in order to save cost, time and effort as well as ensuring that a specific type of ammunition that was pressure tested according to one standard is safe to use in a specific weapon that was tested according to another. The main aim of this study was to investigate the possibility of finding a scientific correlation between the mean peak pressure values obtained by the NATO EPVAT and CIP test standards for 7.62 x 51mm NATO Ball Reference Ammunition through derived and validated equations with fixed conversion factors in order to convert “actual” Mean Peak Pressure (MPP) and Standard Deviation (SD) values obtained by NATO EPVAT test to predict those values in the C.I.P equivalent and calculate the Average Maximum Pressure (Ptmax).Thirty 7.62 x 51mm NATO BALL reference ammo were tested according to NATO EPVAT and C.I.P and the mean peak pressure conversion factor (FMPP) was found to be 0.974, while the standard deviation conversion factor (FSD) was 1.381. Both conversion factors were used to convert the MPP and SD values obtained by EPVAT testing of the reference ammunition, to their C.I.P Equivalent. These C.I.P converted values were then used to calculate (Predict) the Maximum Average Pressure Ptmax which was 3540.26 bar. Validation of this result was achieved by conducting an actual C.I.P pressure test on the same amount of reference ammunition which resulted in a Ptmax of 3422.40 bar with an error percentage between actual and predicted Ptmax of 3.54%.

Separation of sabot petals is a critical procedure in intermediate ballistics affecting accuracy of the final hit of the penetrator of the fired ammunition round. Design of sabot petals has been an important concern supported by modeling and simulation studies of sabot separation. Computational fluid dynamics studies of the same have hitherto addressed feasibility of coupled fluid dynamics and 6 DOF simulations employing fixed sabot designs. The use of dynamical meshes for supersonic air flow is in its infancy as each simulation run for a given sabot geometry is highly computationally intensive. Good support can still be offered to sabot petal design by using analytical models, like the one by Reinecke and Guillot and its subsequent improvements. We present and study an improved model which better captures the role of the sabot petal scoop. In particular, we study how changes in the shape of the scoop affects the sabot separation kinematics. The sabot assembly assumed to be axisymmetric in shape and other major design parameters are kept the same when the scoop shape is changed.

Gun accuracy is influenced by several parameters during the in-bore projectile travel. The aim of this study is to determine the influence of gun barrel straightness on projectile exit conditions, in order to understand how to improve weapon accuracy. A tridimensional numerical model is created in order to vary this parameter and to study its influence on the ammunition behavior during internal ballistics. The model will be validated using experimental firings, particularly with accelerometers embedded in the ammunition. These firings have required the development of an optoelectronic system to transmit accelerations in real time. The good correlation of the experimental and numerical results proves the representativeness of the model. The model can then be used now to perform parametric analysis and to determine the most penalizing straightness shapes for gun accuracy.

The development of high accuracy rifle has uncovered a need for understanding the movement of the bullet in muzzle flow. Recent researches have always been focused on computational fluid dynamics (CFD) and experimental research on the muzzle flow, which released many data, such as velocity and base pressure drop of projectile. Due to CFD tests are timeconsuming, a dynamic model for spatial motion of projectile is established. In this model an empirical relationship is utilized for the base pressure of projectile, and the model is assumed that the base pressure is along the axis of barrel which applied on the tail cone of the bullet; The spatial motion equations deduced from the mass center motion equations and Euler equations of motion are solved with Runge-Kutta method. A 7.62 caliber bullet is tested to verify the dynamic model. The result agrees with the CFD and experimental data, which shows that the model is applicable in predicting the translational motions, besides the angular motion of projectile is also presented, which can be the initial condition of exterior ballistics to analyses the firing accuracy.

To avoid gas escaping from the gap between tube and projectile in mortar, some seal grooves structures are designed. The blow-by phenomena should be considered in the simulation of interior ballistics. In order to investigate the gas leakage, computational fluid dynamic study of seal groove during the mortar interior ballistic process is presented in this paper. By the seal groove, the pressure near the outlet decreases directly. The mass flow rate of the structures without seal groove and with seal groove at the inlet are similar. However, the mass flow rate of the structure without seal groove at the outlet is obviously bigger than that of structures with different seal grooves. The results show that the seal groove such as trapezoid seal groove can decrease the gas leakage and improve the interior ballistic performance. The further study on structure optimization will be a reference for the mortar design.

Current military operations often comprise urban scenarios. Thus, masonry objects offer protection and shielding against weapon effects. To effectively engage enemy forces and targets the munitions applied must be capable of perforating masonry materials and of delivering lethal force behind structures. Building structures may consist of soft materials like clay or adobe as well as of hard materials like brick or (reinforced) concrete. They might be set up of double or triple layers in combination with mortar opposing a very inhomogeneous target compared to classic armored vehicles. The penetration of these structures by small and medium caliber projectiles results in projectile deflection and tumbling. Also large shot to shot scatter of residual velocities is associated with these nonlinear trajectories, as has been observed in penetration testing and high-fidelity numerical simulations (such as FEM). The prediction of weapon effects with standard accredited vulnerability tools, like UniVeMo (Universelles Verwundbarkeitsmodell) in Germany, has to consider the observed effects but also has to provide results in acceptable time frames. Therefore fast-running methods have to be developed. This presentation will demonstrate the IABG approach deriving regression functions and/or look-up tables for small and mid-caliber penetration processes in masonry materials. Based on numerous simulation and experimental results the phenomena observed will be described, the way to fast running modules including the application of analytical tools will be explained, and final results and samples will be demonstrated.

The main goal of this research is to create a new ballistic helmet concept able to defeat high velocity rifle bullets, specifically the 7.62 x 39 M43 round. The current design consists of four layers, where the first layer is responsible for the deformation and breaking up of the projectile, the second layer for stopping the projectile, the third layer for reducing the back face deformation, and the fourth and last layer for absorbing the shock wave send into the helmet shell, next to the back face deflection of the latter. Whereas previous research gave possible solutions for the first three layers, this work focuses on the feasibility of the fourth, shock-absorbing layer. A finite element model approach was used to see the influence of the shock-absorbing layer on the risk on behind-helmet blunt trauma and to determine a suitable standoff based on a maximum force injury criterion.

Most spacecraft have at least one pressurized vessel on board. For robotic spacecraft, it is usually a liquid propellant tank. In some satellite or spacecraft designs, the fuel tank or some other pressurized vessel is necessarily exposed to the hazards of space, including the micro-meteoroid and orbital debris (MMOD) environment. Because of the potential of serious mission-threatening damage that might result following an on-orbit MMOD impact, a primary design consideration of such spacecraft is the anticipation and mitigation of the possible damage that might occur in the event of such an impact. While considerable energy and effort has been expended in the study of the response of non-pressurized spacecraft components to MMOD impacts, technical and safety challenges have limited the number of tests that have been conducted on pressurized elements of such spacecraft. As a result, several investigators have taken to modelling pressurized vessels as flat plates under uniaxial or bi-axial tensile loading conditions. This paper presents the development of a data-driven equation for initially stressed flat composite material plates that differentiates between impact conditions which, given a plate perforation, would result in only a hole or crack from those which would cause catastrophic plate failure / rupture. If this equation were subsequently shown to also model the rupture/no-rupture behavior of actual COPVs, then it could also be used to appropriately tailor the design parameters and/or operating conditions of a pressurized tank. Tank designs could be adjusted so that if that tank were to be struck and perforated by the impact of an MMOD particle, then only a hole would occur and additional sizable debris would not be created as a result of that impact.

A proof of concept non-destructive test system has been designed and tested that is capable of characterizing both Cartridge Cases and projectiles, both intact as well as those discharged from a weapon. The technique utilizes a device equipped with a proprietary and patented sensor which detects energy reflected off the unit under test. This detected signal undergoes Fourier Transformation which creates a signature which can them be used for comparison with other existing samples for matching purposes. This system has been shown to be able to match Cartridge Cases as well as projectiles to a degree that could potentially allow matching of samples to a degree sufficient to determine like production lot members, and other linked criteria. This is system is projected to be much more cost effective than current systems and the hope is to have units installed in Forensic vehicles and laboratories nationwide, and globally for government and law enforcement applications. By standardizing the measurement system, data can be stored in a repository similar to current repositories, for remote access to stored data as well as to be able to upload measured signatures directly to the data base. The system has shown good results in early tests and is ready to progress through further testing to a preproduction stage, once funding has been secured to enable this.

Today, improving the weight/load carrying capacity ratio of a part is the matter of studies in most of the scientific and industrial areas. Autofrettage dimensions, the amount of material removed from outer and inner radius while manufacturing and the service pressure applied affect the residual stress distribution throughout the wall thickness and hence the load-bearing capacity of a thick-walled cylinder. Calculation of residual stresses after autofrettage process and optimization of autofrettage outline dimensions by using the amount of service pressures applied are common issues in literature. In this study, mandrel-cylinder tube interference dimensions were renovated by using traditional methods for swage autofrettage process of a gun barrel. Also, the residual stresses in the cylinder after autofrettage process, inside and outside material removal process and the variable service pressure throughout the cylinder applied were taken into consideration and incorporated into the design. By using the constrained optimization method, wall thickness (thus the weight) was optimized (minimized) to achieve the specified safety factor along the length of the cylinder. For the same cylinder, the results of the suggested analytical/with residual stress calculation approach were compared to analytical/without residual stress calculation results and numerical topology optimization method calculation results. Since the experimental measurement results are not yet available, it was not possible to compare them with the calculation results. The suggested approach enabled 22.9% extra weight reduction in proportion to numerical topology optimization and enabled 4.2% extra weight reduction in proportion to analytical/without residual stress optimization. Using this approach, the gain from residual stresses after autofrettage operation, the loss of residual stresses after material removal, and the effects of service pressures can be taken into account for each stage of design.

Composite solid propellant is prepared using tri-modal Ammonium perchlorate (AP) containing coarse, fine and ultrafine fractions of AP with average particle size (APS) 340, 40 and 5 μm respectively, in various compositions and their rheological, mechanical and burn rate characteristics are evaluated. The optimum combination of AP coarse to fine to ultrafine weight fraction was obtained by testing of series of propellant samples by varying the AP fractions at fixed solid loading. The concentration of aluminium was maintained constant throughout the experiments for ballistics requirement. The propellant formulation prepared using AP with coarse to fine to ultrafine ratio of 67:24:9 has lowest viscosity for the propellant paste and highest tensile strength due to dense packing as supported by the literature. A minimum modulus value was also observed at 9 wt. % of ultrafine AP concentration indicates the maximum solids packing density at this ratio of AP fractions. The burn rate is evaluated at different pressures to obtain pressure exponent. Incorporation of ultrafine fraction of AP in propellant increased burn rate without adversely affecting the pressure exponent. Higher solid loading propellants are prepared by increased AP concentration from 67 to 71 wt. % using AP with coarse to fine to ultrafine ratio of 67:24:9. Higher solid content up to 89 wt. % was achieved and hence increased solid motor performance. The unloading viscosity showed a trend with increased AP content and the propellant couldn't able to cast beyond 71 wt. % of AP. Mechanical properties were also studied and from the experiments noticed that % elongation decreased with increased AP content from 67 to 71 wt.%, whereas tensile strength and modulus increased. Burn rate increased with increased AP content and observed that pressure exponent also increased and it is high for the propellant containing with 71 wt.% of AP due to increased oxidiser to fuel ratio. Catalysed composite solid propellant is prepared by using burn rate modifiers Copper chromite and Iron oxide. Addition of Copper chromite and Iron oxide has enhanced the burn rate of tri-modal AP based composite solid propellant. The catalytic propensity of copper chromite is higher than that of iron oxide. The pressure exponent increased with the catalyst concentration and the values obtained are compatible for solid rocket motor applications.

This study investigates the characteristics of shaped charge jet formations with a high-polymer liner, as well as its penetration capabilities, by experimental and numerical methods. Two types of liner materials were studied: a high-polymer PTFE liner and a pure copper liner. Pulse x-ray photographic technology was employed to observe the distent jet of the PTFE liner and the particulate jet of the copper liner. The simulation and jet radiography results show that the two jet behaviors with particulate and radial dispersion are ductile behaviors, and the two jet behaviors appear to be related to the liner material. The distent jet formation result from the liner material was crushed at the high-pressure region because the sudden pressure increase produces radial velocity, which results in lateral expansion. Compared with the typical copper penetration performance, the polymer distent jet had a larger aperture and lower penetration depth. Clearly, because of the low polymer liner density, this device will have limited penetration compared to that of a copper liner. The simulated results strongly agree with the experimental results.

The End game for a kill vehicle of Hit-to-Kill Missile is very critical, as it depends on its variable divert and attitude correction capabilities. A Solid DACS provides quick reaction propulsion that positions the vehicle to intercept its target. The Pulsed Solid DACS provides propulsion for control error correction and for vehicle maneuvering. The attitude control systems (ACS) have six thrusters to provide roll, pitch and yaw control. These thrusters act synergistically and precisely aim the vehicle seeker to properly view the target. The four divert thrusters provide short/ long pulses to quickly and accurately position the kill vehicle for a collision with target. A high burn rate propellant is used to meet the divert and attitude control thrust requirement. Four divert thrusters have the variable throat areas for the quick divert of the kill vehicle. The nozzle throat areas are throttled such that the mass flow is met for the required thrust for each thruster. Pintle valves are used for the throat area throttling purpose. The attitude control thrusters have the fixed throat area which will be used for the attitude control capability of kill vehicle. A pulsed motor has been designed to operate for divert thrust and attitude control for first few seconds and second motor (second pulse) will operate with a time delay after first motor operation. This is achieved by configuring an annular motor around the first rocket motor (which get emptied during the first pulse) and separated by two pulse separation diaphragms (PSD). The propellant gases flow into the first pulse motor and actuated by the first pulse rocket motor nozzles to produce variable divert and fixed attitude control thrust for second pulse duration.

In the present work experimental data from seven perforated (7PF) JA2 propellant combustion in a micro closed bomb is presented and the linear burning rate of the JA2 propellant is determined. The burn rate measurement is based on a sophisticated lumped parameter model which accounts among other things for arbitrary cross sectional propellant geometries with the help of the ICT-Cellular-Combustion-Algorithm (ICCA), pressure dependent thermophysical parameters and heat loss. The model is used to construct a vivacity based objective function which depends on the parameters of the empirical law for the linear burning velocity. With the Nelder-Mead downhill simplex optimization algorithm the objective function is minimized and the burn rate parameters determined. The comparison of the results to published data show that with the new burn rate measurement method the linear burning rate can be determined with great accuracy even when only a few propellant grains with a total propellant mass of less than 8 g per shot are used.

We explore two initial conditions on the same numerical grid to simulate blast overpressure at crew locations in the far-field. The first utilizes a 2D axisymmetric simulation mapped into a 3D quarter symmetry domain (2D-IC) as an initial condition for the exterior blast overpressure simulation. The purpose of this method is to reduce runtime from days to hours where the simulation lends itself to axisymmetric (i.e. the interior of a cannon). The second utilizes a full 3D quarter symmetry simulation (3D-IC) started from propellant ignition to propagation to the position of interest in the exterior of the tube. These results are then compared to experimental blast overpressure results for the same position. The conclusions from the study are that both the 2D-IC and 3D-IC are valid methods for numerically determining blast overpressure. However, the two initial condition approaches vary significantly compared to one another.

This work is a continuation of the research presented at the 29th ISB, concerning an analysis of the dynamic vivacity function determined on the basis of closed vessel tests results. The main conclusion of the analysis was that the form of the vivacity function strongly depends on the loading density. In order to analyze this dependence for the loading densities ranging from 300 to 700 kg/m3, the valved closed vessel (VCV) was used. The maximum value of the time derivative of pressure was attributed to the end of the pyrostatic period. The dynamic vivacity curves for this period were determined. The strong dependence on the loading density was revealed. This was explained by differences in the temperature distribution inside propellant grains. The effect of this distribution on the values of the burning rate was analyzed. Conclusions concerning the method of analyzing closed vessel test data were formulated.

This paper provides a summary of a comparative study of three different backing materials that can be used for ballistic testing of body armour. The study used standardised test packs, shot patterns, velocities and test rounds to build a data set. The aim being to understand how these mediums work and their use in the assessment of behind armour blunt trauma. In addition, the data set enables the variance of the different mediums to be greater understood. This is an extended abstract paper and associated poster summarising initial results of work conducted as part of my PhD at Cranfield University. The full paper is planned to be published in early 2018.

Carbon fiber reinforced barrel can be applied to the lightweight design of railgun. The composite barrel will improve railgun performance with better flexibility and small muzzle disturbance. With magnetism-thermal-structure coupled analysis, this paper gives the transient thermal stress distribution of the composite barrel for single shot. Besides, two cases of a rapid fire with five shots per minute and ten shots per minute are studied respectively. In the end, dynamic strength of the composite barrel has been checked with specialized failure modes for both fiber wraps and metal rails. The results show that temperature rising of rails for single shot is higher with fiber laminate housing than with insulated steel plate housing. When the railgun undergoes a rapid fire, thermal stress of the composite housing and rails has an increasing tendency. The maximum rate of fire for the railgun must be limited to an acceptable level, considering that all materials of the composite barrel should remain linear elastic.

The replacement of plastrite by Hexomax leads to determinate and validate the equation of state parameters of the detonation products, in the goal to make performances numerical calculations of this energetic material. The Chapman- Jouguet state is calculated using two ways, firstly from simulations with the thermo-chemical code named SIAME developed by the CEA for the French DGA and conventional defense applications, secondly from an approach based on empirical relations available in the literature. The hypothesis of a mean value for the polytropic coefficient in the ambient state of detonation products and also for exponential decreasing members coefficients of JWL equation allows to reach to other parameters according the strength to respect the detonation CJ state. Inside SIAME, these coefficients are obtained by minimization of the JWL equation isentropic form of the detonation products CJ expansion. Used in a hydrodynamical calculation code (OURANOS, LS-DYNA), JWL parameters allow to compare the numerical simulation results to experimental results of the cylinder test. The correlation is very good with parameters from the thermo-chemical simulation. The empirical method looks like a FREM (« Fast Running Engineer Model ») leading to a good approximative solution of JWL parameters when the necessary enthalpy of formation for the thermo-chemical simulation is not available. The JWL parameters are used afterwards to evaluate the Hexomax blast effects for aerial detonation.

Shock initiation of explosives has been at the focus of many important studies over the years. One of the interesting topics in this field deals with the ability of a projectile, or jet, to initiate an explosive through impact. To this end, Held introduced the critical v2d initiation criterion, which has shown great success for the case of bare explosives. However, recent experimental results have questioned the generality of this criterion for cases of covered explosives. In this work we employ the Lee-Tarver model, to numerically explore the shock initiation of PBX9404 explosive, subjected to the impact of long rods. We demonstrate the generic difference between bare and covered explosives and identify the crossover between these two cases. We conclude by mapping the run to detonation distance, for rods of different velocities and diameters, for covered explosives.

The terminal behaviour and trauma produced by penetrating projectiles is known to depend on the mechanical and physical properties of the tissue. Impact with bone is thought to cause injuries of greater severity due to a potential increase in bullet instability, deformation and/or fragmentation. The interaction of flat bones like the ribs and the effect of the rib cage in thoracic ballistic trauma remain unclear. The aim of the study was to determine the effect of ribs on the terminal behaviour of penetrating projectiles and the resulting trauma produced via a gelatin-based model. Three sample groups were compared: (i) plain gelatin, (ii) rib-embedded gelatin with direct rib impact, and (iii) rib-embedded gelatin with intercostal muscle penetration (between ribs). Two projectile calibers (5.56 mm and 7.62 mm) and two impact velocities (for 5.56 mm) were evaluated. The influence of ribs on the terminal effects of penetrating projectiles appears to be minimal.

In this effort, a series of BKNO3 and nitrocellulose based igniters were formulated. Their thermodynamic output and gaseous properties were calculated. Their laboratory scale sensitivities were demonstrated to be significantly better than that of benite. Their performance characteristics based on closed bomb were evaluated and compared to that of both black powder and benite. These new igniters are more akin to benite in terms of relative force, and are quite varied with regard to relative quickness and relative vivacity. These new igniter formulations will provide gun system designers a means to vary the brisance and speed with which an igniter exerts its mechanism of action on the propellant, thus allowing them to tailor the ignition system through choice of material.

The standardized ballistic testing methodologies for Personal Protective Equipment that are currently used, incorporate the use of common mass production projectiles. The discrepancies in their attributes, material composition, geometry, assembly, production tolerances, introduce extra variability in their responses, for the stochastic physical phenomenon, that is ballistic impact. A prototype of a Bullet Simulating Projectile (BSP) was developed for replacing commercial 9mm projectiles, strongly limiting the unknown variables that normally manifest themselves in ballistic impact tests. The effectiveness of the proposed BSP design was examined against soft protection targets in terms of penetrability and induced behind armor blunt trauma (BABT). The proposed BSP design was used versus multilayered non-crimp aramid fabric packs backed against Weible red plastilina. The resistance to perforation and the BABT were measured and compared with commercial 9mm projectiles. A finite element model was developed for investigating the local response of multilayered non-crimp aramid fabrics against the 9mm Parabellum projectile and the BSP. The fabric is presented as a dual ±45o angle-ply yarn based model with its yarns being interconnected using cohesive formulation elements. The results were compared with the experimental data.

A new propellant was prepared from the base propellant grain by impregnation with the blasting oil, followed by deterring with the deterrent in water medium. The combustion performance of this propellant was investigated by means of closed-bomb test and interior ballistic test. The barrel erosion was characterized by erosion test. It is found that this propellant burns more progressively and the value of Pr increases from 0.035 to 0.445 when compared with the base gun propellant. The interior ballistic performance for this propellant charge is improved obviously and the muzzle velocity increases by 5.0% from 886.6 m/s to 931.3 m/s. This propellant has the characteristic of low temperature sensitivity at the same time. The barrel erosion of this propellant decreases by 16.3% at least. This new propellant has the advantages of higher combustion progressivity, higher muzzle velocity, low erosion and low temperature sensitivity.