Small Caliber Ammunition Research Articles

Design and process of force-electric fusion for electromagnetic driven Si based MEMS S&A

In order to meet the technical requirements for precise control of the arming time in high-dynamic environments and ammunition safety, this article proposes a silicon-based MEMS safety system force-electric fusion design scheme for small-caliber ammunition platforms. Modeling and computational analysis are conducted on the sensitive units in S&A. A mechanical equilibrium model is established to study the centrifugal overload and electromagnetic forces, followed by verification through dynamic simulation. The design aimed to achieve the safety and arming control of the MEMS security system using a plate-type electromagnetic driving scheme. A low driving energy electromagnetic coil model is designed, and the driving capability of the electromagnetic coil is analyzed. It is found that under the condition of a distance of 0.1mm and 8V, a driving force of 270mN could be achieved. Considering the complex operating conditions during the arming process, a low damping model is developed for the arming degree of the MEMS arming device. After the design is completed, the S&A and electromagnetic coils are processed and prepared using deep silicon etching and microcasting techniques. Finally, threshold verification is conducted for the recoil and centrifugal arming mechanisms of the S&A. The designed S&A ultimately achieved a size of less than or equal to ∅20mm.

Magneto-electric self-powered electrical output and ignition performance of a multifunctional projectile under impact loading

To meet the requirements of miniaturized multifunctional ammunition with force-thermal-electromagnetic, a new concept is adopted to develop a small-caliber ammunition, which uses a magneto-electric self-powered ignition system with high overload generated by penetrating the target to ignite the active material inside the ammunition. In this paper, the force and motion of the magnet during projectile penetrating into the target under different impact loads are analyzed by joint simulation of ABAQUS/Explicit and Maxwell softwares, and the ignition reliability and relative motion velocity of magnet and coil are evaluated by the ignition system. The results show that the self-powdered ignition system can be ignited reliably when the geometric size of the magnet is Φ × L = 8 × 12 mm2, the turn number of the coil is 350 and the relative motion speed of the magnet and the coil is higher than 40 m/s. The ignition threshold energy of the military electric ignition head used in experiment is calculated between 0.29∼0.35 mJ. The maximum and minimum ignition delay times are 139 μs and 485 μs in experiments, respectively, and the corresponding relationship is determined by adjusting the relative position of the coil, magnet and magnet's geometric size, which can provide a controllable ignition delay time for penetrating targets with different natural characteristics.

Study of Energetic Materials of Double Base Propellant for Small Caliber Ammunition

Double Base Propellants (DBP) has been frequently utilized in the fields of rocket propellant and gun propellant. DBP has various advantages over conventional propellants, including easy formulation, high energy, and smokelessness. The research conducted in literature studies was applied by referring to the various energetic materials for DBP. The composition of a DBP consists of energetic raw material of Nitrocellulose (NC) and Nitroglycerin (NG). According to data analysis, NC can be manufactured from the raw material Nata de Coco, which has a nitrogen content of more than 12,5% in NC, which is in line with the levels of conventional military and propellant raw materials. Meanwhile, SMX (1,4-dinitrate-2,3-dinitro-2,3bis (nitratomethylene) butane) or GAP (Glycidyl Azide Polymer) on double-base propellants is suggested as potential alternative energy sources that can be utilized to substitute NG. The choice of new energetic material is influenced by the fact that Nata de Coco is abundant in Indonesia, while SMX and GAP in terms of manufacturing and handling are safety. The several parameters to characterize double-base propellants include thermal analysis, microstructure, surface area, burning rate value, and gaseous product. The results of thermal properties by DSC analysis on a DBP based on NC+NG+TiO2-trifluoroacrylate showed a change in exothermic decomposition at a temperature of 199.2oC. Meanwhile, TGA analysis of a DBP based on NC+NG+GAP showed mass decomposition at temperature 199,3oC. Furthermore, it was found that thermoplastic elastomers GAP have a significant effect on increasing the low-temperature mechanical properties of double-base propellants. As a result, the literature studies approach, which includes consideration of alternative energetic raw materials and characterization for double-base propellants, is the recommendation for obtaining superior performance double-base propellants with energetic materials.

The Granulation Methods of Double Base Propellant for Small Caliber Ammunition: A Review

One of the most essential unit procedures in propellant production is granulation, or particle enlargement through agglomeration. The granulation process transforms small fine or coarse particles into huge agglomerates known as granules. The granulation process converts fine powders into free-flowing, dust-free granules that are easier to compress, affecting propellant grain size. The propellant industry expects produce quality propellant which can increase the performance of weapon. Method of propellant granulation should have optimized in accordance with the size of grain. One of the most active areas of double base propellant research is the development of granulation method. The literature review method was used to obtain data, by using the keywords double base propellant research, and the criteria for granulation method. The data obtained in the form of the results of the development granulation method to produce qualify size grain of propellant to increase performance. The data shows that the method of granulation can be conventional or modern based on development of technology. Production on laboratory scale widely uses sieving or mesh to form granules of propellant. This method widely known as conventional method. Development of technology influence method of granulation in manufacturing propellant, for example extrusion with vertical hydraulic press, ram extruder, screw extruder, and cutting uses rotary cutting machine.

The evolutionary process and damage characteristics to the target of jet flame produced by the Al/PTFE mixed powder in a small caliber projectile with through-hole

The unsintered Al/PTFE mixed powder is a kind of active material with high energy. Different from traditional explosives, the reactive speed of the Al/PTFE mixed powder is slow, but the deflagration duration is long. When it is applied in a projectile, it can form a new weapon for special purposes. In this paper, the Al/PTFE mixed powder is applied in a projectile with a through-hole and combined with the self-energy supply activation system, a new type of small caliber ammunition is designed. The evolutionary process and duration of the jet flame under high-speed impact and static explosion are analyzed, respectively. And the damage characteristics of the jet flame to the target are analyzed from the perspectives of thermal and overpressure damages. Meanwhile, the internal energy of the jet flame in the confined space is calculated. The results show that the evolutionary process of the jet flame is similar, and the flame propagates rapidly along the crack in the target up to 175 ms under impact ignition and static explosion. The maximum overpressure and radiant temperature can reach 1.89 GPa and 5500 K, respectively. The gas’s internal energy and flash radiant energy in the confined space account for 50.9% of the total released energy.

Random Forest in the Tests of Small Caliber Ammunition

Abstract In the introduction of this article the method of building a random forest model is presented, which can be used for both classification and regression tasks. The process of designing the random forest module was characterized, paying attention to the classification tasks module, which was used to build the author’s model. Based on the test results, a random forest model was designed for 7,62 mm ammunition with T-45 tracer projectile. Predictors were specified and values of stop parameters and process stop formulas were determined, on the basis of which a random forest module was built. An analysis of the resulting random forest model was made in terms of assessing its prediction and risk assessment. Finally, the designed random forest model has been refined by adding another 50 trees to the model. The enlarged random forest model occurred to be slightly stronger and it should be implemented.

Research on piezoelectric stacked generator and its application

In response to the energy density and fast activation requirements of small caliber ammunition fuzes for power supplies, this paper designs a piezoelectric stacked physical power supply that can generate electrical energy using the setback acceleration generated at the moment of ammunition firing as a power source. The paper designs the structure of the power supply according to the performance parameters of the selected piezoelectric materials and tests the power generation performance of the power supply using a simulated experimental setup. The experimental results demonstrate that the output voltage of the piezoelectric power supply has a linear relationship with the load. When the piezoelectric power supply charges the capacitor, the voltage across the energy storage capacitor also increases approximately with the increase of load, and the piezoelectric stacked power supply designed in this paper can meet the requirements of small caliber ammunition.

Risk evaluation of ballistic penetration by small caliber ammunition of live-fire shoot house facilities with comparison to numerical and experimental results

The development of advanced small caliber weapon systems has resulted in rounds with more material penetration capabilities. The increased capabilities may mean that existing live-fire facilities will no longer be adequate for the training and certification of military and law enforcement personnel. Constraints on training in many live-fire shoot house facilities are already in place, with some allowing only single round impact during training. With little understanding of the probability of perforation, or failure, of existing containment systems, this study evaluates risk by studying the single round impact of small caliber ammunition against live-fire shoot house containment systems constructed from AR500 steel panels with two-inch ballistic rubber covering. An analytical and numerical study was conducted using an existing model for steel penetration developed by Alekseevskii-Tate and the EPIC finite element code. A modified form of the advancing cavity model for the ballistic resistance of the target material was used to account for the relatively unconfined material resulting from the studied impacts. These results are then compared to experimental tests conducted by Goodman for rounds of various small calibers impacting live-fire facility containment systems. Projectile and target characteristics were then modeled as continuous random variables, and Monte Carlo simulations were conducted using the validated analytical model to estimate the probability of a single round impact perforating the live-fire facility containment system. An importance sampling scheme was used to reduce the variance of the solution and provide a more accurate estimate of the probability of failure. The Alekseevskii-Tate model was found to provide accurate estimates of the depth of penetration when compared to experimental and numerical results at ordnance velocities and an estimate of the probability of failure is on the order of 1x10-5. This study provides useful tools for the analysis of existing live-fire facilities against future and existing ammunition, and for the design of new facilities. When coupled with Monte Carlo simulation techniques, a risk-based approach to certify live-fire facilities for use with any variety of small arms ammunition can be applied.

Characterization of the Mechanical Behavior of a Lead Alloy, from Quasi-Static to Dynamic Loading for a Wide Range of Temperatures.

The current needs in terms of ballistic protection for armed forces require an almost constant improvement in performance to face the constantly evolving threats and scenarios. Ballistic tests are conventionally carried out in order to assess and validate the levels of protection. The challenge is to be able to set up a digital protocol and only carry out final validation tests. Indeed, the advantage of digital simulation lies in the possibility of being able to evaluate a wide variety of configurations. In order to obtain reliable results, it is necessary to use sufficiently precise material behavior models to transcribe the phenomena observed during the impact. Our study focuses on the behavior of a small caliber ammunition with a ductile core impacting personal protection. More particularly on the mechanical behavior of the lead alloy core. Thus, compression tests have been carried out on a wide range of deformation rates, from quasi-static behavior to dynamic regime, at different temperatures. The study in dynamic conditions was carried out using split Hopkinson pressure bars. Due to the material properties, the experimental device had to be adapted in order to optimize the propagation of the waves allowing to measure signals (elastic waves). These tests demonstrate the dependency of the stress with strain rate and temperature. Dynamic restoration and recrystallization phenomena, characteristic of a material deformed in its hot working area, have also been identified. The associated oscillations due to Pochhammer–Chree effect, observable on the stress–strain curves, constitute the major problem for the implementation of behavioral models. Finally, a constitutive model sensitive to strain rate and temperature is investigated for ballistic purposes.

Study of the Forming Characteristics of Small-Caliber Ammunition with Circumferential MEFP.

To study the influence of the structural parameters of the ammunition liner of small-caliber ammunition on the forming characteristics of the projectile, an integrated circumferential multiple explosively formed projectile (MEFP) warhead with an integrated shell and the liner was initially designed, and the wall thickness of the liner is variable. LS-DYNA finite-element software is used to simulate the integral circumferential MEFP of the preliminary design, based on the numerical simulation results, the influence of the thickness at the center of the liner, and the curvature radius of the liner on the shape and velocity of the formed projectile. The numerical simulation results show that when the thickness of the center of the liner is constant and the curvature radius increases gradually, the velocity of the formed projectile decreases and the length: Diameter ratio of formed projectile decreases gradually. When the curvature radius of the liner remains unchanged, the velocity of the formed projectile decreases with the increase of the thickness of the center of the liner, and the shape of the formed projectile does not change significantly. The results show that when the design of integrating the shell and the liner was adopted for the integral circumferential MEFP warhead, the shape of the formed projectile is greatly affected by the curvature radius of the liner (curvature radius of inner and outer walls of the liner), but less by the thickness of the center of the liner. The velocity of the formed projectile is affected by the curvature radius of the inner and outer walls of the liner and the thickness of the center of the liner. Moreover, the influence of the thickness of the center of the liner on the velocity of the formed projectile is greater than that of the curvature radius of the outer wall of the liner.

Evaluation of a Sustainable Pyrotechnic Tracer Composition for Small Caliber Ammunition

Recent efforts have aimed to replace the near-infrared (NIR) tracer composition (R-440) currently specified for some types of 7.62 × 51 mm NATO ammunition with a more environmentally sustainable composition (R-680). This report summarizes the two main efforts aimed to evaluate the suitability of such a replacement: (1) establishing a charge weight window for R-680 that meets the tracer depth requirement for 7.62 mm ammunition and (2) comparative characterization of the emission spectra of R-440 and R-680. To this end, the 7.62 mm tracer depth requirement was met only for rounds with net R-680 charge weights ranging from 665 to 745 mg. Static burn testing of pellets derived from R-440 and R-680 showed that both compositions gave similar burning times (∼5 s) and substantially identical NIR output (0.20 W/sr).

Enhanced propellant performance via environmentally friendly curable surface coating

Abstract Surface coating of granular propellants is widely used in a multiplicity of propellants for small, medium and large caliber ammunition. All small caliber ball propellants exhibit burning progressivity due to application of effective deterrent coatings. Large perforated propellant grains have also begun utilizing plasticizing and impregnated deterrent coatings with the purpose of increasing charge weights for greater energy and velocity for the projectile. The deterrent coating and impregnation process utilizes volatile organic compounds (VOCs) and hazardous air pollutants (HAPs) which results in propellants that need to be forced air dried which impacts air quality. Propellants undergo temperature fluctuations during their life. Diffusion coefficients vary exponentially with variations in temperature. A small temperature increase can induce a faster migration, even over a short period of time, which can lead to large deviations in the concentration. This large concentration change in the ammunition becomes a safety or performance liability. The presence of both polymeric deterrents and nitroglycerin(NG) in the nitrocellulose matrix and organic solvents leads to higher diffusion rates. This results in continued emissions of VOCs and HAPs. Conventional polymers tend to partition within the propellant matrix. In other words, localized mixing can occur between the polymer and underlying propellant. This is due to solvent induced softening of the polymer vehicle over the propellant grain. In effect this creates a path where migration can occur. Since nitrate esters, like NG, are relatively small, it can exude to the surface and create a highly unstable and dangerous situation for the warfighter. Curable polymers do not suffer from this partitioning due to “melting” because no VOC solvents are present. They remain surface coated. The small scale characterization testing, such as closed bomb testing, small scale sensitivity, thermal stability, and chemical compatibility, will be presented. The 30 mm gun demonstration firing data at hot, cold, and ambient temperatures will also be presented.

Experimental Study on Penetration of Small Caliber Ammunition into Different Multilayer Compact Armors

Abstract: Nowadays Lightweight armor is very important and used in many applications. Through this study, Penetration behavior was studied through two different types of armors. The first one produced was lightweight composite armor with reducing the number of layers to less than 25 layers of Kevlar using polyurethane rubber resin with high impact and tenacity properties, while the second produced type was a multilayer armor with less than 25 layers of aramid but without using resin Line-x coating in the back. The hand lay-up technique was used for the first type, while the second type was produced by stitching the back layers. Samples were tested for their properties and its ability to defeat 9 mm bullets in protection level IIIA according to NIJ standards. Afterwards the behavior of the small caliber into the two types by the post firing examination tests were studied, where the results resulted in (no penetration) for the two types and complete protection with very lightweight and very thin armor with different reaction of trauma.

Experimental Study on Penetration of Small Caliber Ammunition into Different Multilayer Compact Armors

Experimental Study on Penetration of Small Caliber Ammunition into Different Multilayer Compact Armors

Simulation and experiment investigation on structural design and reinforcement of pyrotechnical sliding micro-actuators

Based on the performance requirements of safety and arming devices in a micro-electro-mechanical fuse system, a type of pyrotechnical sliding micro-actuators were independently developed and modified for use in fuse arming devices of small caliber ammunition, independent of the ammunition launching environment. The modified type of actuator--a sliding micro-actuator with two restraining fins--can effectively reduce the required actuated fuel (initiating explosive) and increase the locking force. Experimental results of thrust tests, locking tests and critical fuel weight tests indicate the reliability of the modified structure, and clarify the structural dimension effect. Both the thrust force and slider deformation for the modified structure shared similar results in simulations and tests. In conclusion, the simply and easily fabricated pyrotechnical sliding micro-actuator with a step structure is able to ultimately perform both the anticipated braking and locking functions, and provides references for the structural design of fuse arming devices.

Comparing Acute Toxicity of Gunshot Particles, from Firing Conventional and Lead-Free Ammunition, in Pulmonary Epithelial Cell Cultures

Numerous studies demonstrated that the use of lead (Pb)-containing ammunition is associated with mainly chronic health problems and also is a burden on the environment and wildlife. Recently, a number of reports showed evidence of undesirable acute health effects related to the use of newly developed Pb-free small-caliber ammunition. In this study, particles from leaded and Pb-free ammunition were collected in liquid collection medium, in a highly controlled chamber, while firing a pistol (9 mm) or a rifle (7.62 × 51 mm). The emitted particles were typically smaller than 4 μm, with the great majority in even smaller size ranges, as shown by gravimetrical analysis and a multistage impactor. Chemical analysis revealed significant differences in content and concentration of several metals in the particles. After administration of the liquids to alveolar and bronchial in vitro cell systems, particles were taken up by the cells; the Pb-free particles displayed higher cytotoxicity (EC50 = 2 μg/cm2) than particles from Pb ammunition. High correlation factors (>0.9) were found between cell death and content of copper and zinc. Particles from both Pb-containing and Pb-free ammunition were able to induce oxidative stress and the proinflammatory marker interleukin (IL)-8 in both in vitro systems. These results support previous findings that indicate an association between gunshot emissions and metal fume fever. This study demonstrates the usefulness of combining chemical data with biological in vitro responses in assessing acute toxicological effects from emissions from firing both Pb and Pb-free ammunition.

Bullet on bullet fragmentation profile in soils

Lead–antimony alloy slugs encased in a brass jackets are common small arms caliber ammunition used for training and target practice. When small caliber ammunition is fired at testing and training ranges, these metals—some of which are toxic—are introduced into the environment. Research was conducted on the effects of bullet on bullet impacts and the resulting bullet fragmentation. The extent of bullet fragmentation, among other factors, affects the formation of mobile metal species from small arms firing ranges. Bullet on bullet impact can increase the surface area to mass ratio of the bullet metal alloys in the soil. The solubility of a metal is typically associated with the specific corrosion rate in the berm environment which is dependent on the surface area of the fragments. The purpose of the study was to analyze the bullet on bullet impact effects in six soil types. Changes in the metal distribution as a result of bullet impact was evaluated through sieve analysis and changes in the particle size distribution. The bullet on bullet impact observed in this study demonstrated a significant and observable shift in the fragmentation profiles for the lead, antimony, and copper in soils after shooting an average of 1050 tungsten-nylon bullets into the legacy lead soils. This study provides new information to assist with determining the potential environmental fate, transport, and environmental availability associated with constant bullet on bullet impact at testing and training ranges.

Effect of Strain Rate on the Simulation of MEMS Safety and Arming Device

Under launch impact load, LIGA nickel that manufacturing MEMS fuze safety and arming (S&A) device will have obvious strain rate effect. By using finite element analysis software ANSYS/LS-DYNA, simulation models of a small-caliber ammunition MEMS fuze setback S&A device with strain rate effect and without strain rate effect were respectively established. The results of the two simulation modules were quite different. Comparisons between experimental results and simulation results show that simulation results considering strain rate effect agree well with experimental results, which proves strain rate effect should not be ignored in the simulation of MEMS S&A device.

Emission Factors for Gases and Particle-Bound Substances Produced by Firing Lead-Free Small-Caliber Ammunition

Lead-free ammunition is becoming increasingly popular because of the environmental and human health issues associated with the use of leaded ammunition. However, there is a lack of data on the emissions produced by firing such ammunition. We report emission factors for toxic gases and particle-bound compounds produced by firing lead-free ammunition in a test chamber. Carbon monoxide, ammonia, and hydrogen cyanide levels within the chamber were analysed by Fourier transform infrared spectroscopy, while total suspended particles and respirable particles were determined gravimetrically. The metal content of the particulate emissions was determined and the associated organic compounds were characterized in detail using a method based on thermal desorption coupled to gas chromatography and mass spectrometry. The particulate matter (∼30 mg/round) consisted primarily of metals such as Cu, Zn, and Fe along with soot arising from incomplete combustion. Nitrogen-containing heterocyclic aromatic compounds such as carbazole, quinolone, and phenazine were responsible for some of the 25 most significant chromatographic peaks, together with PAHs, diphenylamine, and phthalates. Emission factors were determined for PAHs and oxygenated PAHs; the latter were less abundant in the gun smoke particles than in domestic dust and diesel combustion smoke. This may be due to the oxygen-deficient conditions that occur when the gun is fired. By using an electrical low pressure impactor, it was demonstrated that more than 90% of the particles produced immediately after firing the weapon had diameters of less than 30 nm, and so most of the gun smoke particles belonged to the nanoparticle regime.

Theoretical Method Research on a MEMS Safety and Arming Device

With the intelligent development of small-caliber ammunition, the overall size of the fuze is compressed. In this paper, a theoretical method-energy statistical method has been proposed according to the MEMS S&A device. Taking the slider mass, micro-spring stiffness, latch mechanism size, and initial offset distance into account, the conversion relationship among each part of energy in the process is obtained. For an existing structure of MEMS S&A device, known parameters are utilized to reverse the overload value at arming condition. The ANSYS/LS-DYNA finite element analysis software is used for simulation analysis, thereby confirming the feasibility of theoretical calculations. Also, theoretical calculation error ε is obtained, which to be 0.7%. Energy statistical method and simulation analysis serve as theoretical references for the design of the MEMS S&A device.