Ballistic Process Research Articles

Intelligent System for Artillery Mount Autonomous Guidance And Firing Adjustment

The article presents mathematical models, numerical algorithms and a software package for an intelligent system for artillery mount autonomous guidance and adjustment of firing. The software package includes the following components: a module for solving the direct problem of external ballistics, a neural network training module, and a firing guidance and adjustment module. The first module is designed to form a database of computational experiments by repeatedly solving the direct problem of external ballistics under varying firing conditions. In the second module, a neural network is trained to solve the inverse problem of external ballistics using the database generated from computational experiments. The third module implements algorithms for calculating the artillery mount launching angles on a target using a trained neural network and calculating corrections to launching angles based on data on the projectile impact point deviation from the target. Having received data on the artillery mount readiness to fire, the coordinates of the target position and projectile’s impact point received from a digital observer, the software package calculates the necessary launching angles or corrections to them. Launching angles are transferred via text files to the control system of the artillery mount drives, then a shot is fired and the conditions for hitting the target are assessed. The algorithm is then repeated for the next shot or new target. Testing of the developed algorithms for autonomous guidance and shooting correction was carried out using modeling of external ballistics processes in the software package, as well as carrying out experimental testing on a working simulation device of an artillery mount. The developed software package allows visualization of the obtained results and saving the history of the performed operations.

Experimental and Numerical Investigation on Attitude Adjustment Characteristics of Spacecraft with Impulse Thruster

AbstractThe spacecraft serves as an effective tool for the space exploration. The present study is devoted to investigate the yaw attitude adjustment motion of the spacecraft influenced by the reaction-jet control system. A novel spacecraft device with impulse thrusters is designed for the vacuum test. And a synchronous test system, equipped with high-speed cameras, is established to record the motion process of the spacecraft under the various initial setting conditions. Subsequently, a six degrees of the freedom exterior ballistic model is calculated considering the interior ballistic process in the impulse thruster. The experimental results confirm that the position change of the designed device’s center of mass aligns with expectation, and the prediction error of final attitude angle remains below 2%. Based on this foundation, the change rule of the impulse thrust under different main charge loads is explored. The non-linear impulse thrust needs to be coupled with the rotation motion to enhance calculation accuracy. And the position of the center of mass is investigated to illustrate the advantage of the designed spacecraft structure. Finally, the calculation of the ignition interval time required for each target attitude angle is conducted, providing the essential data for further optimization design research. The outcomes from this paper can offer valuable technical means for advancing studies on the spacecraft attitude control.

Simulation of interior ballistic two-phase flow of storage propellant charge

ABSTRACT The launch safety evaluation of artillery considering the properties changes of propellant charge during storage has attracted much attention, and the determination of the interior ballistic process of storage propellant charge has been a bottleneck problem. Large scale firing test is difficult to implement due to its high risk and uncontrollability, and simulation is limited by the difficulty in describing the interaction of propellant parameters. In order to describe the multiple physical fields in the chamber and reveal the influence mechanism of storage on interior ballistic process, the theoretical analysis and physical simulation are combined in this paper. The fracture and the subsequent combustion of the storage propellant charge in the chamber environment were physically simulated, and then, the interior ballistic two-phase flow simulation method considering the fracture of storage propellant charge is proposed by coupling these performance parameters. Though describing the interior ballistic process variation with storage time, this paper provides a practical evaluation method for the interior ballistic performance of energetic materials.

Review of the penetration resistance performance of lightweight ceramic composite armor under high-speed impact

Due to the constant updates in armor materials and structures, as well as the continuously increasing ballistic threats, higher requirements have been put forward for the ballistic performance of lightweight ceramic armor. In this paper, we first studied the types of ballistic threats faced by lightweight armor and determined the range of main materials and various combinations used in common ceramic composite armor, while comparing their performance with other constituent materials. Next, we reviewed the coupling mechanism of the projectile and target during the ballistic penetration process and the energy dissipation mechanism, and discussed the structural parameters that affect the ballistic performance of the ceramic composite armor. Finally, we pointed out the future direction of development for ceramic composite armor, reviewed the coupling mechanism of the projectile and target during the ballistic penetration process and the energy dissipation mechanism, and discussed the structural parameters that affect the ballistic performance of the ceramic composite armor.

Assessing the possibility of using a variable-length launch vehicle with a polymer body for orbiting payload

The object of this study was the motion of an ultralight class variable-length launch vehicle made of a polymer body along the active phase of the trajectory. The work considers the solution to the problem of designing low-cost means of delivery to orbit, namely to the assessment of the possibility of removing the payload by a carrier rocket with a polymer body of variable length beyond the dense atmosphere of the Earth. For this purpose, ballistic projection of the trajectory of the launch vehicle was carried out taking into account overloading; its aerodynamic characteristics and peculiarities of aerothermodynamic processes occurring during flight in the atmospheric phase of the trajectory were determined. The closeness (up to 10 %) of the obtained results with known experimental data is shown. The influence of the aerodynamic force on the parameters of the launch vehicle motion was studied. A flight simulation was conducted, the results of which showed the fundamental possibility of launching a CubeSat 24U class payload using a launch vehicle with a polymer body of variable length to a suborbital trajectory with an altitude of about 300 km. At the same time, the effective longitudinal overload on the body of the launch vehicle does not exceed 4 units, and the temperature on the surface of the body does not exceed 300 K. A feature of the research is the use of a multidisciplinary approach, which implies taking into account the interrelationship of aerodynamic, thermodynamic, and ballistic processes. The established motion parameters, aerodynamic characteristics, and the surface heating temperature of the launch vehicle body are key values for further research on the design and analysis of a launch vehicle with a polymer body of variable length. These data could be used to calculate the mechanical and thermal loads acting on the structure of the launch vehicle during flight

Numerical investigation of the influence of different barrel lengths on the interior ballistic process within an underwater submerged launch

Although underwater submerged launching has been rigorously investigated for decades, there remains a dearth of comprehensive understanding regarding the underwater interior ballistic characteristics for varying barrel lengths. To address this knowledge gap, the present study aims to explore, via numerical simulations, the initial velocity of interior ballistics, projectile drag, and the mechanism of initial flow field formation at the muzzle under various barrel lengths, thereby considering the influence of differing barrel lengths. The five distinct lengths of barrels are expressed as dimensionless ratios of the weight of water column in front of the projectile to the weight of the projectile in order to be more general. Five different ratios of water-to-projectile weight are investigated: 1.0, 1.2, 1.5, 1.8, and 2.0, all possessing identical diameters and evaluated under equivalent launch conditions. Different ratios significantly impact muzzle velocity, with shorter barrels yielding higher muzzle velocities, while ensuring complete propellant combustion. Further investigations indicate that variations in drag constitute the fundamental cause of initial velocity changes. Furthermore, it is observed that barrels of different lengths exhibit identical characteristics at the point of maximum drag. The initial flow field at the muzzle exhibits considerable variations in terms of length, profile dimensions, and intensity. The findings of this study offer valuable insights into exploring the mechanism of submerged launching and will be utilized to investigate the optimal barrel length.

The role of coalescence and ballistic growth on in-situ electrical conduction of cluster-assembled nanostructured Sn films

The electrical conduction of nanostructured Sn films assembled via Supersonic Cluster Beam Deposition is studied in-situ during film growth. The kinetic energy of Sn nanoparticles, in combination with low melting point of Sn, promotes coalescence phenomena, enabling the investigation of their impact on film morphology and on percolation threshold. A percolation threshold occurring at thicknesses much larger than the dimensions of Sn nanoparticles suggests that coalescence leads to the growth of disconnected, island-like structures. The deposition rate is found to influence coalescence dynamics during the early stages of film growth, allowing for the tuning of film microstructure from a more compact, island-like morphology to a more porous structure. The percolation threshold shifts accordingly from 24 nm to 3 nm film thickness. Upon completion of the percolation phase, film resistivity settles at values 2–3 orders of magnitude larger than that of bulk Sn, attributed to the nanogranular nature of cluster-assembled films. During the “3D conduction” phase, resistivity exhibits an increasing trend with thickness following a power law with an exponent value of 0.76–0.78. This behavior is attributed to the decrease in the density of interconnections between particles in the topmost layer during film growth, consistent with expectations in ballistic growth processes.

Ballistic resistance of 7XXX laminate aluminum alloy plates and base alloys subjected to different projectiles

The ballistic impact of two 7XXX aluminum alloys, 7A52-T6 and 7A62-T6, as well as their combination in a 7B52 laminate plate, was simulated and experimentally tested. Three types of projectiles were utilized hard ogival nosed, hard blunt nosed, and 304 steel core projectiles to investigate the ballistic resistance and failure mechanisms of the aluminum alloy targets. Additionally, an existing modified Gurson-Tvergaard-Needleman (GTN) model incorporating shear, void growth, and spalling failure mechanisms, was employed to simulate the ballistic impact process, utilized to analyze energy dissipation during impact. The results reveal that the 7A52 alloy only experiences ductile hole expansion failure, whereas the 7A62 high-strength aluminum alloy undergoes spalling and fragmentation subsequent to penetration, leading to potential impact hazards. Due to its backing layer being the highly ductile 7A52 alloy, the laminate plate will not produce fragments after penetration. The improved GTN model provided better predictions of the impact failure modes of the aluminum alloys. Concerning impact performance, when subjected to hard ogival projectiles, the laminate alloy did not enhance material impact resistance. However, when impacted by blunt-nosed projectiles, the laminate alloy exhibited a 27 % improvement over the 7A52 plate and an 11.9 % increase over the 7A62 plate. Furthermore, when impacted by 304 steel core ogival projectiles, the laminate alloy demonstrated over a 41.3 % improvement compared to the 7A52 plate and over a 15.5 % increase compared to the 7A62 plate. The laminate plate's high ballistic performance was attributed to the increased plastic deformation energy after spalling failure, while ensuring high energy absorption during ductile hole expansion penetration.

Dynamic failure behavior of 7B52 laminated aluminum alloy subjected to deformable projectile impact

The ballistic response and failure mechanisms during the impact of a 304 steel-core projectile on a 7B52 laminated aluminum alloy plate were investigated. The impact resistance of the target plate was obtained through ballistic testing, and a detailed analysis of the fracture mechanism was conducted using microstructure characterization. Furthermore, an enhanced Gurson-Tvergaard-Needleman (GTN) model was employed to simulate the ballistic impact process, as well as the initiation and propagation of fractures. The results revealed significant deformation following the impact of the 304 steel-core projectile on the 7B52-T6 laminated plate. The target plate exhibited spalling failure, shear failure, and ductile hole expansion, with spalling failure being caused by intergranular fracture mechanisms. In the high stress triaxiality regions of the 7A62 alloy, intergranular cracks are prone to occur, and shear stress influences the expansion of the cracks. Fragments following layer cracking adhere to the 7A52 layer, thereby increasing the ballistic resistance surface area. The 7A52 layer on the rear side of the target plate effectively absorbed the projectile's energy through bending and stretching deformation, thereby offering enhanced protection. Furthermore, the spall resistance of the 7B52 laminated plate eliminate secondary damage caused by spall fragments.

Investigation of heat transfer in cracked gun barrels

Heat transfer process significantly affects the life span of gun barrels as it directly associates to the thermoelastic dynamic responses, erosion, and wears of gun barrels. The previous studies regarding the heat transfer in gun barrels were developed in the realm of local theory that is expressed by partial differential equations with the condition of smoothly distributed physical fields, and have rarely studied the cracked gun barrels. However, on one hand, due to manufacturing errors, there inherently exists fractures in realistic gun barrels; on the other hand, the inner wall of the gun barrel wears due to the high-temperature and -speed burning gas generated during the interior ballistic process, as well as the high-speed friction from projectile’s movement, which severely lead more cracks and damages. Therefore, it is of great importance to investigate the heat transfer in cracked gun barrels. In this paper, a non-local heat transfer model for cracked gun barrels is formulated via the bond-based peridynamics. The governing equation is presented in the manner of integration, such that the heat process with the influence of cracks can be readily captured. Numerical results show that the heat energy severely accumulates on the crack surface and as the size of horizon increases, the non-local characteristics of the heat transfer appear to be more pronounced, resulting in a stiffer thermal response.

Synthesis of unsaturated polyurethane oligomer and its application in the 3D printing of composite solid propellants

Propellants are the main source of energy for internal ballistic processes. The use of 3D printing technology is expected to produce propellants with complex geometries. However, limited by the properties of existing printable resins, the mechanical properties of 3D-printed propellants make it difficult to meet the requirements for use. This study deals with the structural design, synthesis, and properties of an unsaturated polyurethane resin (PUA). A photoinitiator was added to this polyurethane resin and a photo-curable elastomer was successfully prepared under UV irradiation with tensile strength and elongation at break of 21.06 MPa and 1119 %, respectively. Then, the resin was mixed with active diluent, initiator, NH4ClO4, and Al particles to prepare the propellant slurry, and the rheological properties of the slurry were investigated. The results show that the propellant pastes have good flowability at 40 °C and are suitable for 3D printing. Finally, solid propellant and insulation samples with complex structures were effectively generated using UV-curable 3D printing technology, in which the tensile strength and elongation at break of the propellant samples were 0.923 MPa and 63.2 %, respectively. The fabrication of the grains with high precision and performance demonstrated the feasibility of the PUA binder in the 3D-printed propellant.

Dynamic engraving characteristics of nylon belt under different charge conditions

Abstract In the present study, a 105 mm short tube gun system was designed to conduct the firing experiments under low charge conditions, which could precisely obtain the projectile displacement data and projectile base pressure data during the engraving process. Besides, a 3-dimensional dynamic engraving FEM-SPH model was established by coupling the internal ballistic process to much authentic investigate the engraving characteristics of the projectile, which were verified and compared through the experiment. On this premise, the influence mechanism and engraving features of the nylon belt were numerically calculated under higher charge conditions. The comparison between the experimental recovery belt and the numerical calculation results shows that the damage to the front of the nylon belt is axial compression wear, while the damage to the back of the nylon belt is circumferential shear wear. The direction of force exerted by the slope chamber and the projectile body on the belt was inconsistent, causing a bulge in the middle of the nylon belt. The more rapid the average boosting rate, the stronger the instantaneous impact on the nylon belt, the larger the stress and the strain damage on the nylon belt, the higher the pressure at the end of the engraving process and the greater the maximum engraving resistance. When the average boosting rate increased from 2.7 MPa⋅ms−1 to 33.0 MPa⋅ms−1, the engraving time was shortened by 73.9%, while the maximum engraving resistance increased by 78.2%.

Micro-ballistic response of thin film polymer grafted nanoparticle monolayers.

Self-assembled polymer grafted nanoparticles (PGNs) are of great interest for their potential to enhance mechanical properties compared to neat polymers and nanocomposites. Apart from volume fraction of nanoparticles, recent experiments have suggested that nanoscale phenomena such as nanoconfinement of grafted chains, altered dynamics and relaxation behavior at the segmental and colloidal scales, and cohesive energy between neighboring coronas are important factors that influence mechanical and rheological properties. How these factors influence the mechanics of thin films subject to micro-ballistic impact remains to be fully understood. Here we examine the micro-ballistic impact resistance of PGN thin films with polymethyl methacrylate (PMMA) grafts using coarse-grained molecular dynamics simulations. The grafted chain length and nanoparticle core densities are systematically varied to understand the influences of interparticle spacing, cohesion, and momentum transfer effects under high-velocity impact. Our findings show that the inter-PGN cohesive energy density (γPGN) is an important parameter for energy absorption. Cohesion energy density is low for short grafts but quickly saturates around entanglement length as adjacent coronas interpenetrate fully. The response of γPGN positively influences specific penetration energy, , which peaks before chain entanglement starts (<Ne). We further divide the ballistic response into three regimes based on grafted chain length: short graft, intermediate graft, and entangled graft. The short grafted PGNs show fragmentation due to almost no cohesion between particles, and the rigid body motion of the nanoparticles absorbs most of the energy. When chains are in the intermediate graft length regime, the film fails by chain pull-out, and unraveling of grafts is the primary dissipation mechanism. The Ashby plot of penetration energy, Ep, indicates ballistic processes are inelastic collisions when grafted chains are short and vary with density in a power law fashion as expected from momentum transfer. The response indicates that a lower nanoparticle weight fraction, ϕwtNP, leads to higher energy absorption per mass, that is, the added mass of nanoparticles does not warrant proportionate increases in energy absorption in the parametric range studied. However, the peak deceleration, Ab, shows a clear positive effect of adding NPs. Finally, PGNs with intermediate chain lengths simultaneously show relatively higher and Ab.

Ballistic and delamination mechanism of CFRP /aluminum laminates subjected to high velocity impact

This work focus on the experimental study of ballistic and delamination mechanism on carbon/epoxy laminates with [-45/90/45/0] stacking sequence. A series of impact tests were carried out on the monolithic CFRP and Al/CFRP/Al laminates targets. The two targets were compared in terms of ballistic limit, energy absorption, penetration process, damage mechanism and interfacial delamination. Results showed that the Al/CFRP/Al laminates with equal thickness had better ballistic performance than that of the monolithic CFRP laminates. The delamination of adjacent layers was mainly controlled by bending moment, uneven stress distribution of interface and mismatch of wave impedance between layers with different lay-up directions. The shear wave propagated between fiber layers in different layering directions, resulting in interlayer crack extension.

Dynamics of stress waves in graded density impactors during the internal ballistic process

Quasi-isentropic loading and unloading, employing graded density impactors (GDIs) as flyers in gas gun-driven plate impact experiments, can provide novel and valuable insights into the equation of state and strength properties of the loaded material. However, the internal ballistic process may lead to spalling or debonding of the GDI due to the intricate interactions between stress waves and interfaces. In this study, the wave propagation in the GDI was analyzed using the multimaterial Lagrangian elastic-plastic model and elastic wave propagation theory. The impact of gradient direction, power-law constant p, and thickness of the first and last layers on the tensile stress was investigated. The outcomes reveal that the mechanism of generating tensile stress varies for two gradient directions. Moreover, adjusting the constant p and the layer thickness may decrease the maximum tensile stress by 74.1% (forward graded) and 95.8% (reverse graded), respectively. The outcomes of this research provide a theoretical and simulation basis for designing and fabricating GDIs to be utilized in quasi-isentropic experiments.

Research on the Process of Dispersing the Bullet by a Large-Size Gasbag with Multiple Inlet Nozzles Based on the Fluid–Structure Interaction Method

AbstractTo meet the needs of the airborne dispenser to disperse large-mass bullets, the dispersal system of large-size gasbag with multiple inlet nozzles was designed and built. The rationality and feasibility of the dispersal system were verified by the experimental study of the interior ballistic process. On this basis, the fluid–structure interaction method was used to simulate and analyze the process of the gasbag propelling the bullet when the number of inlet nozzles is different. The calculation results show that the final shape of the expanded gasbag is pillow shaped, and wrinkles appear at the ends of the long side and in the middle of the short side of the gasbag. The stress at the wrinkles is relatively large, and the stress on the wall of the gasbag with three inlet nozzles is greater than that on the wall of the gasbag with two inlet nozzles. Affected by the changes of flow field in the gasbag and the deformation of the gasbag, the process of the gasbag propelling the bullet is divided into two stages, and there are also two large fluctuation peaks during the change of the acceleration of the bullet. Moreover, the expansion process of gasbag with two inlet nozzles lags behind that of the gasbag with three inlet nozzles, and the maximum acceleration and separation velocity of the bullet are also relatively reduced by 2% and 3%, respectively.

An efficient two-phase flow calculation method based on grid mergence and dimension transformation

Two-phase flow numerical methods are applied in internal ballistics widely, which has made higher fidelity analysis with minimal cost become an urgent demand. Current methods are based on independent dimension, and there is no definite conversion criterion and data transmission method, which have limited the application of efficient hybrid models applied to calculation. In this paper, we propose a hybrid method by linking a two dimensional (2D) model to a one dimensional (1D) model for two-phase flow. First, 1D and 2D two-phase flow models are established according to the flow field states in different phases. Next, the criterion of conversion between the two models is established, which is a quantitative index to judge the degree of radial effect and axial effect. Finally, dimension transformation in the radial direction and grid mergence in the axial direction are conducted to complete the whole computing model. The simulation results show that the hybrid method is more efficient in the interior ballistic process and maintains the level of trust in classical codes. Compared with the 2D method, the hybrid method significantly improves the computational efficiency by 86.5%. By analyzing the state in the chamber, the accuracy of the conversion criterion is confirmed. This criterion can be used as the transformation criterion of the hybrid model to form the standard multi-dimensional calculation transformation criterion of interior ballistics and may be promising for the rapid simulation of two-phase flow in interior ballistics.

Launch Dynamic Simulation of a Compressed-Air Launcher for Fire Suppression

This paper focuses on improving fire suppression performance through the use of compressed-air launching technology. A launch dynamics calculation model of a compressed-air launcher is presented, developed using VC++ programming, to simulate the acceleration process of a fire-extinguishing bomb in a barrel. By analyzing the influences of various structural and initial parameters on interior ballistics variations, the effectiveness of the calculation model and program in accurately simulating the launching process is demonstrated. The calculation results indicate that the bore pressure follows a similar trend to that of traditional gunpowder launching. Additionally, it is found that specific structural parameters, such as nozzle diameter and gas cylinder volume, have a direct impact on interior ballistics variations. Notably, the nozzle diameter positively affects the peak pressure, muzzle velocity, gas transfer efficiency, and launch efficiency. To ensure an optimal launch effect and efficiency, the nozzle diameter should be selected to be more than half of the launcher caliber. Similarly, the gas cylinder volume positively influences the peak pressure and muzzle velocity while negatively affecting the gas transfer efficiency and launch efficiency. Furthermore, the initial pressure in the gas cylinder exhibits a positive linear relationship with both the peak pressure and muzzle velocity but a negative linear relationship with the gas transfer efficiency and launch efficiency. The loading position minimally impacts the peak pressure and muzzle velocity but slightly enhances the gas transfer efficiency and launch efficiency. Finally, it is observed that launch angles do not affect the interior ballistic process. The research findings provide valuable theoretical guidance for determining the working parameters of compressed-air accelerated fire-extinguishing bombs.

An internal ballistic model of electromagnetic railgun based on PFN coupled with multi-physical field and experimental validation

To accelerate the practicality of electromagnetic railguns, it is necessary to use a combination of three-dimensional numerical simulation and experiments to study the mechanism of bore damage. In this paper, a three-dimensional numerical model of the augmented railgun with four parallel unconventional rails is introduced to simulate the internal ballistic process and realize the multi-physics field coupling calculation of the rail gun, and a test experiment of a medium-caliber electromagnetic launcher powered by pulse formation network (PFN) is carried out. Various test methods such as spectrometer, fiber grating and high-speed camera are used to test several parameters such as muzzle initial velocity, transient magnetic field strength and stress-strain of rail. Combining the simulation results and experimental data, the damage condition of the contact surface is analyzed.

Research on multiphase flow field characteristics of underwater gun double‐tube parallel firing

AbstractThe underwater muzzle flow field formed by the double‐tube launch will interfere with each other, resulting in large changes in the characteristic parameters of the flow field and shock wave morphology. Therefore, the numerical model of three‐dimensional unsteady multiphase flow for underwater gun‐sealed launching was established. Meanwhile, an experimental platform for the underwater sealed launch was built and the rationality of the model was verified. The interior ballistic process compiled by UDF was coupled with the dynamic mesh technology, and the VOF multiphase flow model integrated with the Schnerr‐Sauer cavitation model was chosen to numerically calculate the muzzle flow field of the 30 mm underwater gun double‐tube parallel launch, and the numerical results were compared to those of the single‐tube launch. The results show that the gas is expelled from the muzzle and rapidly expands to form a gas cavity, and the “necking” phenomenon of the gas cavity occurs at 0.2 ms, while the Mach disk structure has formed. Due to the mutual interference between the flow fields formed by each tube, the diameters of the Mach disk are slightly different, and the flow field structure has a certain asymmetry in the evolution process. The core area of the shock wave is bowl‐shaped of the single‐tube launch, while it is not completely filled of the double‐tube launch. Within 0.5 ms, the diameter of the Mach disk increases monotonously when the single‐tube is launched, while it first increases and then decays by a double‐tube.