Ballistic Parameter Research Articles

Modified Epoxy Resin on the Burning Behavior and Mechanical Properties of Aramid Fiber Composite.

Aramid fiber/epoxy resin (AF/EP) composite has been heavily used as an impact protection material due to its excellent mechanical properties and lightweight merits. Meanwhile, it is also necessary to concern the flammability of matrix resin and the wick effect of aramid fiber, which would constitute a fire risk in harsh environments. In this work, a multifunctional flame-retardant modifier (EAD) was incorporated into the AF/EP system to improve the flame retardation. The addition of 5 wt% EAD made the AF/EP composite exhibit a high limiting oxygen index (LOI) value of 37.5%, self-extinguishment, as well as decreased total heat release and total smoke release. The results from thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) demonstrated that the treated composites maintained good thermal stability. Due to the combined action of covalent and noncovalent bonds in the matrix-rich region, the interfacial bonding improved, which endowed AF/EP composite with strengthening and toughening effects. Compared with the control sample AF/EP, the tensile strength and ballistic parameter (V50) of the sample with 5 wt% EAD increased by 17% and 10%, accompanied with ductile failure mode. Furthermore, the flame-retardant mechanism was obtained by analyzing the actions in condensed and gaseous phases. Thanks to good compatibility and interfacial adhesion, the incorporation of EAD solved the inconsistent issue between flame retardancy and mechanical properties, which further expanded the application of AF/EP composite in the protection field.

Ferrocene-fullerene dyad as a novel burn rate modifier for propellants

The burn rate of composite rocket propellants serves as a critical ballistic parameter in the construction of a rocket engine. Due to their large surface areas, carbon-based materials such as carbon nanotubes, graphene, and fullerene have demonstrated promising results as burn rate modifiers (BRMs) for propellants. Unlike their inorganic counterparts, these materials, being combustible, contribute to energy output besides enhancing the burn rate. This study reported a ferrocene-fullerene dyad as a BRM prepared through the thermal decomposition of ammonium perchlorate (AP) in composite solid propellants. By incorporating 0.6 wt% of the dyad, the burn rate of the prepared propellants increased by 70%, accompanied by a rise in their calorific value.

Modeling of non-intrinsic noise in nanometer metal oxide semiconductor field effect transistors

With the proportional reduction of metal–oxide–semiconductor field effect transistor (MOSFET) devices, the short channel effect, the parasitic effect, and the field strength effect are significantly enhanced, the proportion of parasitic resistance increases, and the non-intrinsic noise also increases, which seriously affects the working efficiency of the device. However, existing research mainly focuses on the intrinsic noise of MOSFET, and there is little research on the non-intrinsic noise; furthermore, the models describing the relationship between non-intrinsic noise, device structure, and bias have not yet been addressed. Therefore, in this paper, 90, 65, 32, 10, and 5 nm MOSFETs are studied. The rate of the intrinsic ballistic parameter is introduced to set up the source–drain current model and the non-intrinsic noise model. The source–drain current model is consistent with the theoretical model, numerical simulation, and experimental results in the literature. Finally, the relationship between the non-intrinsic noise and the bias and the device parameters are analyzed, and the conclusion is helpful to improve the working efficiency, lifetime, and response speed of nanoscale MOSFET devices.

Effect of cascade size and damage rate on α’ precipitate stability in Fe-15Cr

Samples of a Fe-15Cr model alloy with an established α' precipitate population were irradiated with 1.25 MeV electrons, 1.5 MeV protons, or 4.4 MeV Fe2+/3+ ions over a range of damage rates to doses of 1 or 10 dpa at 400°C to determine the roles of cascade size and damage rate on the stability of α'. Results showed that α' precipitate size and chromium content increased with dpa for electron irradiations. Proton irradiation also resulted in increases in α' precipitate size and Cr content, but at a slower rate than with electrons due to the influence of ballistic dissolution. Self-ion irradiations caused a reduction in the size and Cr content of α' with dose, and above a threshold damage rate of 1–3 × 10−4 dpa/s, the precipitates were completely dissolved. The ballistic dissolution parameter for self-ion irradiations calculated from both the Nelson-Hudson-Mazey model and a mixing model was in the range 2–5 × 1020 atoms/m2‧dpa compared to a value of ∼9 × 1019 atoms/m2‧dpa for proton irradiation, and explains the different behaviors of the precipitates for these two irradiating particles. Overall, it was found that cascade size strongly determines the stability of α' precipitates and damage rate has its major impact on the rate at which α' precipitates grow or dissolve.

On-board BDS dynamic filtering ballistic determination and precision evaluation

Abstract BeiDou navigation satellite system (BDS) receivers on-board cannot give real-time positioning precision in tracking missile and carrier rocket. In this article, the dynamic filtered optimal estimation theory is applied to the highly dynamic on-board BDS ballistic parameter solution, an optimally constrained geometric dilution precision (GDOP) constellation selection strategy is proposed, a mathematical model based on dynamic filtered estimation for the ballistic determination and precision estimation of the on-board BDS is established, and an analysis of the on-board BDS positioning precision is carried out using the observed data. The calculation results show that the dynamic filter positioning algorithm is simple, practical, and reliable, which can effectively suppress and reduce the random errors of ballistic parameters and significantly improve the positioning precision, fully satisfying the needs of high dynamic and high precision navigation and positioning users, and has good application prospects.

Computerized simulations and modelling for evaluation of ballistic and security parameters of explosives for civil use

Explosives are chemical compounds - substances or mixtures of substances that have a large amount of energy and which under the influence of external actions decompose suddenly, violently with the release of heat and the formation of gases capable of performing a mechanical work. Due to their specific characteristics, these products are used, both in the civil field and in industry, for the execution of works such as: extraction from the massif, in mines or quarries of useful rocks, execution of mining works (galleries) for opening and preparing deposits for exploitation, tunnels, wells, road constructions, railways, canals, demolition of foundations / civil / industrial buildings that have become unusable, geophysical-seism metric surveys, etc. Research in the field of use of explosives for civil use in various industrial and civil applications requires in-depth knowledge of areas such as the phenomenology of explosion, the behaviour of materials in shock waves, the dynamics of structures, seismic engineering, etc. The design of these types of processes requires the consideration, with a relative approximation, of the degree of danger due to the design of fragments resulting from detonation, vibrations, pressures, tensions created in the space affected by the explosion, generation of explosion gases, etc. legislation in force, being an important indicator regarding the classification, handling, storage and transport in the assessment and management of the risks related to these operations. The paper presents a series of computer simulations, both of the ballistic parameter regarding the working capacity of the explosives, and of the security parameter regarding the impact sensitivity.

Analytical potential of 3D data in the ballistic analyses of lithic projectiles

The total entry area of a projectile to the impacted object is a key ballistic parameter of lithic projectiles. Together with the assumed or experimentally testified penetration depth, it forms the first reception of the wounding capability of an individual projectile point, i.e., of the permanent wounding cavity volume. Mathematical operations are used to calculate the entry area, for which the manually measured dimensions of the projectile form input data. Nevertheless, these methods reconstruct only the cross-sectional area at only one point of the longitudinal axis of the object. Here, we propose a method of using high-resolution 3D data for precise measurements of the real entry area of a projectile, even in the case of barbed projectiles whose barbs exceed the width of the projectile body, as well as in cases of projectiles with an asymmetric cross-section. The proposed method of using 3D models to read the numerically expressed values of ballistic parameters was used to analyse almost 400 lithic archery projectiles found in the eastern part of Central Europe, dating from the Late Eneolithic and Early Bronze Age, a culminating period for lithic archery projectiles in the archaeological record.

Aerodynamic Control System for a Deployable Re-entry Capsule

Deployable aerobrakes for Earth re-entry capsules may offer many advantages in the near future, including the opportunity to recover on Earth payloads and samples from Space with reduced risks and costs with respect to conventional systems. Such capsules can be accommodated in the selected launcher in folded configuration, optimizing the available volume, and when foreseen by the mission profile the aerobrake can be deployed in order to increase the surface exposed to the hypersonic flow and therefore to reduce the ballistic parameter.The ballistic parameter reduction offers as main advantage the opportunity to perform an atmospheric re-entry with reduced aerothermal and mechanical loads. It makes also possible the use of relatively lightweight and cheap thermal protection materials.There are plenty of algorithms and control methods for classical re-entry capsules, such as the Orion and Soyuz re-entry modules. However, a lot of attention is now paid towards how to control low ballistic coefficient capsules with inflatable and mechanically deployable heat shield.The aim of this study is to prove the feasibility of an aerodynamic control system, applied to a mechanically deployable re-entry capsule, in order to increase landing precision at the targeted site.The deployable heat shield is equipped with an actuation system, consisting of eight aerodynamic surfaces, referred to as flaps. The assumed control strategy is to deflect the flaps independently, in order to trim the capsule and produce enough lift and side force to give downrange and cross range maneuverability during the re-entry phase.A control algorithm was developed, implemented and tested in a 3DOF simulation environment. Capsule performances both for uncontrolled ballistic re-entries and for controlled lift re-entries starting from a low Earth orbit have been assessed, verifying the capability of the controller in guiding the capsule toward the chosen target.Monte Carlo simulations were run assuming errors and uncertainties at the de-orbit burn, and the control system has been proved to obtain good results in reducing dispersions at the landing site.

Aerodynamics of ducted re-entry vehicles

Ballistic parameter plays a major role in determining the re-entry trajectory. Lower ballistic coefficient offers an optimal re-entry, wherein the vehicle decelerates higher up in the atmosphere thereby decreasing the imposed aerothermal loads. The current computational study proposes an add-on, to the existing Orion-based re-entry vehicle: a duct circumventing the capsule from the shoulder to the base, to improve the aerocapture ability of the re-entry vehicle. The design cases are categorised based on a non-dimensional parameter termed the Annular Area Ratio (AAR). Dragand ballistic coefficient of the Ducted Re-entry Vehicles (DRVs) at various Mach numbers are evaluated and compared with those of the baseline model. The results show that the proposed design increases the drag for all the AARs considered in the subsonic regime. In the supersonic regime, ducted models of higher AAR are more promising with the increase in Mach number. DRVs also exhibit lower ballistic coefficients than their baseline counterparts.

Ballistic behavior of epoxy matrix composites reinforced with piassava fiber against high energy ammunition

Multilayered Armor Systems are low density plates used in personal protection against high-impact energy ammunition. Such system promotes effective protection, by dissipating the projectile energy and preventing the penetration of fragments. Kevlar™ is commonly used as one of the layers. However, recently, cost-effectives composites reinforced with natural fibers have been considered as an alternative. This work aimed to evaluate the performance of epoxy matrix composites reinforced with stiffer natural piassava fibers as a standing alone target against high energy ammunition. Composites with up to 50vol% of piassava fibers were produced by press molding. The influence of the volume fraction in the main failure mode observed and the limit velocity ballistic parameter were determined. Macro and microscopically analyses were performed to determinate the failure mechanism. Statistical analyses were used to evaluate the results obtained. It was verified that the 50vol% reinforced composites were those that presented the best performance, which was found comparable to the results obtained for Kevlar™.

An optimization scheme for a multilayer armour module against 7.62 mm armour piercing projectile

This study presents a methodology to find the optimal sequence and thicknesses of individual material layers in a multilayer armour module. The methodology is demonstrated with application to three different metal alloys: Armox-500T, Ti-6Al-4V and Al-2024. Numerical simulations are performed first to study the ballistic impact behaviour of these three materials using AUTODYN-3D code. The results of numerical simulations are compared with experimental results for validating the numerical models. Thereafter, a three-layer armour module consisting of these three materials is optimized to defeat 7.62 armour piercing projectile with minimum weight. The optimization process involves carrying a set of numerical simulations based on the design of experiment approach to generate a response surface for the ballistic performance of a composite module. A new ballistic performance parameter is introduced to measure the ballistic response of the module by combining depth of penetration and residual velocity of the projectile to bring uniformity between two cases of partial and complete penetration. The proposed parameter provides more information on ballistic performance. The response surface for ballistic performance parameter is generated in terms of thicknesses for six possible combinations of three material layers. The adequacy of the proposed optimization scheme is confirmed with ballistic experiments. The sequence Armox-500T/Ti-6Al-4V/Al-2024 with thicknesses 5.5, 8.5 and 13 mm, respectively, is found to be the best against 7.62 mm armour piercing projectile. Furthermore, the performance of each individual material is compared with an optimized three-layer armour module. The composite module is found to be weight efficient over Armox-500T, Al-2024 and provides better thickness efficiency over Al-2024. The weight efficiency and thickness efficiency of Ti-6Al-4V are found to be comparable to the composite module. This study emphasizes the necessity of developing new procedures to provide reliable estimates of design parameters for a multilayer armour module.

Critical Velocity of High-Performance Yarn Transversely Impacted by Razor Blade

A ballistic parameter that influences the ballistic performances of a high-performance yarn is the critical velocity. The critical velocity is defined as the projectile striking velocity that causes instantaneous rupture of the yarn upon impact. In this study, we performed ballistic experiments to determine the critical velocity of a Twaron® yarn transversely impacted by a razor blade. A high-speed camera was integrated into the experimental apparatus to capture the in-situ deformation of the yarn. The experimental critical velocity demonstrated a reduction compared to the critical velocity predicted by the classical theory. The high-speed images revealed the yarn specimen failed from the projectile side toward the free end when impacted by the razor blade. To improve the prediction capability, the Euler–Bernoulli beam and Hertzian contact models were used to predict the critical velocity. For the Euler–Bernoulli beam model, the critical velocity was obtained by assuming the specimen ruptured instantaneously when the maximum flexural strain reached the ultimate tensile strain of the yarn upon impact. On the other hand, for the Hertzian contact model, the yarn was assumed to fail when the indentation depth was equivalent to the diameter of the yarn. The errors between the average critical velocities determined from experiments and the predicted critical velocities were around 19% and 48% for the Euler–Bernoulli beam model and Hertzian contact model, respectively.

State Prediction of High-speed Ballistic Vehicles with Gaussian Process

This paper proposes a new method of predicting the future state of a ballistic target trajectory. There have been a number of estimation methods that utilize the variations of Kalman filters, and the prediction of the future states followed the simple propagations of the target dynamic equations. However, these simple propagations suffered from no observation of the future state, so this propagation could not estimate a key parameter of the dynamics equation, such as the ballistic coefficient. We resolved this limitation by applying a data-driven approach to predict the ballistic coefficient. From this learning of the ballistic coefficient, we calculated the future state with the future ballistic parameter that differs over time. Our proposed model shows the better performance than the traditional simple propagation method in this state prediction task. The value of this research could be recognized as an application of machine learning techniques to the aerodynamics domains. Our framework suggests how to maximize the synergy by linking the traditional filtering aproaches and diverse machine learning techniques, i.e., Gaussian process regression, support vector regression and regularized linear regression.

Kompjuterska simulacija spoljne balistike pištolja primenom dva različita zakona otpora vazduha (na primeru pištolja 7.62 mm TT)

A description of a pistol (rifle) cartridge often involves two ballistic coefficients that characterize its ballistic qualities with respect to various air resistance laws (ARLs). How close are the obtained ballistic trajectories with varied ARL specifications and what are the differences between them? How to evaluate ballistics if the ARLs are to be expressed in various mathematical forms? In this paper, the evaluation of external ballistics trajectories is given for two ARLs (the law brought in 1943 and the Siacci law). All the obtained results relate to the TT pistol with 7.62 × 25mm Tokarev cartridge. The paper also presents the answer to the question: how to calculate the ballistic trajectory if the ARL is expressed as a rational function, piecewise function or spline. For the 1943 ARL, a graphical interpretation of the function Cd (i, v) in the form of a surface is shown. This paper shows that, due to the selection of ballistic coefficients, it is possible to obtain sufficiently similar form of ballistic trajectories. A method of graphical comparison of external ballistic parameters is presented as well as the mathematical tools for quantitative analysis of a shape of ballistic curves. The difference between the two trajectories is proposed to be estimated using a relative error in regard to a selected ballistic parameter. Computer simulation considered for the 1943 and Siacci ARLs for the 7.62×25mm Tokarev cartridge indicates that the profiles of the function of instantaneous projectile velocity vs time of flight (TOF) had the greatest non-coincidence in relation to other ballistic parameters (e.g. horizontal range, height of the trajectory, etc.) The obtained maximum of the relative error was 0.8%. Its magnitude localizes at the point of impact.

Numerical Study on the Ballistic Impact Response of Aramid Fabric- epoxy Laminated Composites by Armor Piercing Projectile

This paper presents the results from experiments and numerical simulations on the ballistic impact of 10mm thick aramid fabric-epoxy composite laminates by a 7.62mm armor piercing projectile at varying impact velocities. Post perforated residual velocity (RV), contact duration of projectile with the target and ballistic limit (BL) of composite were simulated using a finite element code HyperWorks-Radioss. Interaction of projectile with composite laminates was captured by high speed video. The predicted ballistic parameter from simulation compared well with the precision experimental results. The simulated energy and stress distribution during impact of projectile on composite laminate showed marked difference with variation in impact velocities (SV). The magnitude and duration of stress as well as the contact force was found to increase when projectile impacted at lower SV thus enhancing the extent of delaminating and the core damage area and the trend was reversed for higher SV. The findings corroborate the bullet inflicted damage of composite laminates experimentally determined by ultrasonic C-scan.

A Study on Earth Re-entry Capsules with Deployable Aerobrakes for Recoverable Microgravity Experiments

Deployable aerobrakes for Earth re-entry capsules may offer many advantages in the near future, including the opportunity to recover on Earth scientific payloads from the Space with reduced risks and costs with respect to conventional systems. Such capsules can be accommodated in the selected launcher in folded configuration optimizing the available volume and, when planned by the mission profile, the aerobrake can be deployed in order to increase the surface exposed to the hypersonic flow and therefore to reduce the ballistic parameter. This can offer as main advantage the opportunity to perform an aerodynamic de-orbit of the system without the need of a dedicated propulsive subsystem and an atmospheric re-entry with reduced aerothermal and mechanical loads making possible the use of relatively lightweight and cheap thermal protection system materials. To ensure the recovery of the capsule, the deployable surface can be modulated to obtain the aerodynamic control of the de-orbit trajectory in order to correctly target the capsule towards the selected landing site for post-flight analyses and operations. The main objective of the work is to present a number of feasible mission profiles for orbital platforms to/from Low Earth Orbit aimed in particular at scientific experiments in microgravity conditions. In addition, a suborbital scenario for a technological demonstrator, useful to experimentally verify the system applicability before the design of orbital missions, is also presented and discussed.

Unscented Particle Filter Algorithm for Ballistic Target Tracking

At present, the ballistic Target tracking has a higher demand in convergence rate and tracking precision of filter algorithm. In the paper, a filter algorithm was improved based on particle filter. The algorithm was carried out from the aspects such as particle degradation and particle diversity lack. A novel ballistic coefficient parameter model was built, and was expanded to the state vector for filtering. Finally, the improved algorithm was simulated by MATLAB software. The simulation results show that the algorithm can obtain better convergence speed and tracking precision.

New Concepts of Deployable De-Orbit and Re-Entry Systems for CubeSat Miniaturized Satellites

In the present work new concepts of de-orbit and re-entry modules for standard CubeSats are presented. On the one hand, these modules can be very useful to contrast the growing phenomenon of the Space debris and, on the other hand, to recover Cubesat payload and components after the end of the mission. The concepts are mainly based on deployable, umbrella-like, structures, useful to perform de-orbit and re-entry operations taking advantage from a substantial reduction of the ballistic coefficient. In the de-orbit configuration the deployable structure works only as an aerobrake. In this case the satellite lifetime may be strongly reduced, making it possible to match the CubeSat maximum decay requirement of 25 years, even for altitudes larger than 700 km. In the Earth re-entry configuration the ballistic parameter reduction produces also a sensible decrease of the aerothermal loads on the system, giving the opportunity to recover payload, potential data and satellite components. In this case the umbrella-like structure has both the function to protect the capsule and to control de-orbit and re-entry trajectories, in order to safely reach the desired landing site. The structure can be deployed by means of preloaded springs or other actuators and, once the umbrella is opened, the reference surface can be adjusted to control the trajectory with a kinematic mechanism driven by an electro-mechanical actuator.

Grain size gradient length scale in ballistic properties optimization of functionally graded nanocrystalline steel plates

The last few years have highlighted the existence of two relevant length scales in the quest to ultrahigh-strength polycrystalline metals. Whereas the microstructural length scale – e.g. grain or twin size – has mainly be linked to the well-established Hall–Petch relationship, the sample length scale – e.g. nanopillar size – has also proven to be at least as relevant, especially in microscale structures. In this letter, a series of ballistic tests on functionally graded nanocrystalline plates are used as a basis for the justification of a “grain size gradient length scale” as an additional ballistic properties optimization parameter.

Ballistic Measurement and Parameter Estimation of Ballistic Missile with Early Warning Satellite

Space infrared early warning satellite is an important platform for detecting ballistic missile launch and trajectory. This paper established observation satellite motion model, and the motion state of the satellite at any time was gotten based on its initial information by numerical integration methods. According the theory of double satellites location and satellite observation data of ballistic missile, the observation trajectory of ballistic missile was fitted. The trajectory was used to build the motion model of ballistic missile, and the position, speed and other parameters of the ballistic missile can be inferred. Finally, simulation experiment was conducted.