Projectile Velocity Research Articles

Analysis of the Differences in the Optimum Triggering Positions and Projectile Velocities in Multistage Induction Coilguns for Different Arrangements of the Drive Coil Current Directions

Analysis of the Differences in the Optimum Triggering Positions and Projectile Velocities in Multistage Induction Coilguns for Different Arrangements of the Drive Coil Current Directions

Ballistic performance of optimised light weight composite armour

This research paper presents a comprehensive investigation into the response of a 3D finite element model when subjected to 7.62 AP projectiles. The study utilises Hetherington's armour composite equation and incorporates the Johnson-Holmquist material model to analyse the strength and failure criteria of the ceramic and Kevlar/epoxy components, respectively. The results highlight the remarkable resilience of the composite armour, demonstrating its ability to withstand projectile velocities up to 1500 m/s. However, as the ballistic velocity limit increases, the armour experiences significant damage, including projectile erosion and panel delamination. Through numerical simulations and advanced modelling techniques, the paper thoroughly explores the failure modes and energy absorption characteristics of composite armour systems under projectile impact. It investigates key parameters such as velocity, acceleration, kinetic energy, internal energy, pressure distribution, displacement, and damage progression. The analysis reveals a progressive decrease in kinetic energy as the projectile interacts with the armour, underscoring the crucial role of energy absorption in preventing projectile penetration. Moreover, the impact velocity influences the distribution of internal energy within the composite armour, with higher velocities leading to greater energy absorption up to a threshold limit. The study also determines the ballistic limit velocity (V50) using the velocity history approach and validates the findings with existing literature. Overall, the research provides valuable insights into the limitations of composite armour and offers important recommendations for designing and improving materials to achieve superior ballistic protection. It emphasises the significance of reaching the maximum ballistic limit while maintaining a lightweight armour structure by optimising the total armour thickness. This study contributes to the advancement of armour technology and enhances our understanding of the behaviour of composite materials under high-velocity impacts. It offers valuable guidance for the development of more robust armour systems suitable for various defence and protection applications.

Performance of reinforced lightweight geopolymer composite panels subjected to windborne debris impacts

Lightweight panels have been widely employed as building envelopes in construction. As a result of the rising demand for environmentally friendly building materials, the authors recently developed a lightweight geopolymer composite (LGC) material and investigated the performance of reinforced LGC panels under static loading. Superior performance of LGC panels as compared to conventional panels such as autoclaved aerated concrete (AAC) panels has been observed, demonstrating their potential applications. During strong winds, building envelopes might be subjected to windborne debris impact, which could threaten residents and facilities and lead to structural failure. To explore the application potentials of LGC panels in strong wind regions, in this study, the performances of LGC panels subjected to windborne debris impact were investigated and compared with those of AAC panels by using a pneumatic cannon testing system. The failure modes and damage levels under different impact scenarios of LGC and AAC panels and their impact resistance capacities were obtained, compared and quantified in terms of the projectile residual velocity, penetration length and opening size. The effects of matrix materials, panel thicknesses, impact locations, reinforcement spacings and projectile impact velocities on their impact resistance performance were analyzed. For comparison, the punching shear capacities of the panels were also quasi-statically tested and analyzed subjected to the same projectile employed in the impact tests.

Ballistic properties of curaua-aramid laminated hybrid composites for military helmet

The present research aimed to develop laminated hybrid-composite with aramid woven fabric and curaua non-woven mat, to evaluate the possibility of using as military ballistic helmets. It explores the potential of hybrid solutions, which are more socio-environmentally sustainable and cheaper. All hybrid composites were produced in non-alternate layers model. In addition to hybrid configurations, epoxy laminated composites reinforced with only aramid woven fabric or only curaua non-woven mat were also investigated, with 73 and 58 vol.% of reinforcement, respectively. The cold compression molding process was used for all composites. The ballistic characterization was performed through protection level determination and residual velocity tests to estimate the ballistic limit and absorbed energy, with their corresponding reduction maps. As results, composites with 15 layers of aramid (52 vol.%) and one layer of curaua (15 vol.%) obtained the maximum level of ballistic protection. For composites with two layers of curaua the ballistic limit estimate was 292 m/s, which is ∼15% lower than the limit of the 9 mm projectile velocity corresponding to the maximum level (level II), compared to the composite commonly used in ballistic helmets. Curaua non-woven mat structure and its positioning behind the aramid woven fabric, as well as the lower total number of layers, reduced the ballistic resistance capacity of the hybrid composites. Although the proposed configurations with curaua non-woven mat did not meet the ballistic level requirement of the Brazilian COBRA helmet, these mentioned results are a strong indication of the enormous potential of hybrid composite for military helmet applications.

Experimental study on ballistic stability of truncated cone projectile in high-speed oblique water entry

In this paper, the high-speed photography technique was used to study the high-speed oblique water entry of truncated cone projectiles, and the effects of nose shape, projectile velocity and entry angle on the cavity and ballistic characteristics of oblique water entry were discussed. The experimental results show that the influence of nose shape on the oblique water entry cavity and ballistic characteristics is related to the nose wetted area. For the same type of projectile, with the increase of projectile velocity, the cavity size becomes larger at the same penetration displacement and the surface closure time gets longer. Moreover, with the increase of entry angle, the surface closure time decreases, the velocity attenuation gets faster, at the same penetration displacement the cavity opening length becomes shorter and the cavity asymmetry weakens. Additionally, the results indicate that the trajectory stability of the truncated cone projectile varies under different water entry velocities and attitude angles.

Projectile Impact on Plain and Reinforced Concrete Slabs

Reinforced concrete is a material frequently used in protective structures and infrastructure exposed to extreme loading. In this study, the ballistic perforation resistance of 100 mm thick plain and reinforced concrete slabs impacted by 20 mm ogive-nose steel projectiles was investigated both experimentally and numerically. Two different reinforcement configurations were used to investigate the effect of rebar diameter and spacing. Concrete with nominal unconfined compressive strength of 75 MPa was used to cast material test specimens and slabs. Ballistic impact tests were performed in a compressed gas gun facility. The mechanical properties of the concrete were found using standardised tests and two-dimensional digital image correlation, and the constitutive relation was described by a modified version of the Holmquist-Johnson-Cook model. Finite element models in LS-DYNA reproduced the projectile residual velocity in good agreement with the experimental results. The primary objective of the study was thus to validate a rather simple constitutive relation intended for large scale numerical simulations of concrete structures exposed to ballistic impact loading, while a secondary objective was to investigate the effect of reinforcement on the ballistic perforation resistance of concrete slabs both experimentally and numerically since the literature is somewhat inconsistent on this matter.

Evaluation of hypervelocity impact of micrometeoroids and orbital debris on next-generation space solar cells

This paper discusses the hypervelocity impacts of micrometeoroids and orbital debris (MMODs) on inverted metamorphic triple-junction (IMM3J) and perovskite solar cells, which are much thinner than conventional triple-junction (3J) solar cells. We experimentally found that IMM3J solar cells can suffer from short-circuit faults due to the hypervelocity impacts of MMODs, unlike conventional 3J cells, and determined the projectile diameters and velocities that could cause them using a model proposed by Burt. No short-circuit mode was identified in perovskite solar cells, but they had open-circuit faults several days after the hypervelocity impact experiment, which are possibly attributed to the decomposition of the perovskite crystal by moisture in the air due to the broken seal.

Numerical Investigation of the Oblique Detonation Waves and Stability in a Super-Detonative Ram Accelerator

This study numerically investigates the effects of diluent gas proportion, the overdrive factor, and throat width on the wave structure and thrust performance of a ram accelerator operating in super-detonative mode. For premixed gas of a high energy density, a typical unstart oblique detonation wave system is observed due to the ignition on the front wedge of the projectile, and the detonation waves move downstream to the shoulder as the energy density decreases. In the start range of the overdrive factor, the wave position also shows a tendency to move downstream as the projectile velocity increases, accompanied by oscillations of the wave surface and thrust. As the throat width increases, the wave standing position changes non-monotonously, with an interval of upstream movement and Mach reflection. The typical wave structure of a ram accelerator in super-detonative mode is identified, as well as the unstart stable wave features and the unstable process for choking, which can provide theoretical guidance for avoiding unstart issues in ram accelerators and optimizing their performance.

Numerical Simulation of Anti-penetration Performance of Ceramic/Aramid Fiber/PE-UHMW Composite Armor

In order to study the anti-penetration performance of ceramic/aramid fiber/PE-UHMW composite armor, based on the FEM-SPH coupling algorithm, SPH model is established for brittle ceramic materials to simulate the formation of ceramic cone, crack propagation and fragmentation splash process. The failure mode on aramid fiber and PE-UHMW is analyzed. The influence of different projectile velocities and impact points on the anti-penetration performance of the composite armor are analyzed. The results show that the ceramic panel in the composite armor absorbs part of the kinetic energy of the projectile through passivation, fragmentation of the projectile and panel fragmentation. The failure modes of aramid laminates are mainly delamination shear failure, bending deformation and fiber tensile fracture. The failure modes of PE-UHMW laminates are mainly compression shear failure of the projectile facing surface and small-scale delamination tensile failure of the back layer fiber. When the projectile velocity is less than the ballistic limit, the energy absorption of composite armor and the maximum deformation of back plate increase with the increase of projectile velocity. When the projectile velocity is greater than the ballistic limit, the energy absorption rate of composite armor begins to decrease. When the impact point of the projectile is located at the edge of the ceramic block, the ceramic can’t effectively consume the kinetic energy of the projectile, and the composite armor presents bad performance.

Effects of dynamic prestress on silicon carbide ceramic against long rod impact

It is well known that silicon carbide (SiC) ceramic is a pressure dependent material, where the compressive strength increases as the pressure increases. So, it is an effective way to improve the ballistic performance of SiC ceramic by introducing prestress on ceramics surface. In this paper, the concept of dynamic prestress on SiC ceramic by energetic materials was proposed. Five key factors, including the time of projectiles contact targets, velocity of the long rod projectiles (V p), prestress rising stage time (T r), prestress descent stage time (T d) and peak pressure of prestress (P k), were selected to investigate the effect of dynamic prestress on SiC ceramic targets against long rod impact. The effect of dynamic prestress on the ballistic performance of SiC ceramic were investigated, and the dynamic prestress path which can increase the protection capability of SiC ceramic was given. The results indicated that, in most cases, the ballistic performance of the dynamic prestressed SiC ceramic targets against long rod projectiles impact was improved. However, it was also revealed that not all dynamic prestressing can improve the ballistic performance of SiC ceramic targets. It will be benefit to the ballistic performance of SiC ceramic by controlling the prestress time to make sure the moment of the long rod projectile impacts the target in between T 2 and T 4. The sequence of influence degree of each factor on the erosion length of long rod projectile is the velocity of long rod projectiles (V p), prestress descent stage time (T d), peak pressure of prestress (P k) and prestress rising stage time (T r). The erosion length of long rod projectile decreases with the increase of V p, and increases with the increase of prestress descent stage time (T d), peak pressure of prestress (P k) and prestress rising stage time (T r).

Fire Control Arithmetic on MRSI of Electromagnetic Guns

In order to improve the firing density and damage efficiency of the electromagnetic gun, the control algorithm of multiple rounds simultaneous impact(MRSI) of the electromagnetic gun was established by controlling the initial velocity of projectile and the time interval of the projectile launch. Under the premise that the electromagnetic gun can effectively improve the strike density and damage efficiency, the allowable distance error and the allowable flight time error are set, the fourth-order Runge Kutta method is used to calculate the outer ballistic. According to Pareto genetic algorithm, the objective function, namely two allowable errors, is optimized to obtain the optimal solution of muzzle velocity and angle of multiple projectiles. The simulation verifies that the electromagnetic gun can achieve multiple rounds simultaneous impact in different ranges, and verifies the feasibility of the algorithm to achieve multiple rounds simultaneous impact, which is of great significance to improve the damage efficiency and fire density of the electromagnetic gun in the future.

Analysis of Projectile Impact Resisting Characteristics of Hollow Triangular Matrix Structure

The numerical simulation of engineering structural elements and spatial combination form of the polarizing body using common engineering materials is carried out, and the triangular hole matrix space combination structure is proposed. The penetration depth and deflection angle of the projectile under different projectile velocities and incident positions are obtained by numerical simulation of the projectile impacting the composite structure under various working conditions. At the same time, through the comparative study of ordinary solid shell shielding structures, it is found that the higher the projectile velocity, the higher the shell shielding effectiveness of triangular hole matrix space composite structure.

Research on Timing Compensation of Shadow Photograph System with Three-sequence Laser Sparking

The accuracy of the laser sparking time interval measurement plays a key role in the measurement results when the projectile velocity is measured by shadow photograph system with three-sequence laser sparking. By comparing with the original single-chip measurement results, it was found that there was a certain deviation in the measurement results of the laser sparking time. Then the principle of the laser sparking time measurement circuit is introduced in detail, and the reasons for this error phenomenon are summarized. And analyze the original laser sparking time measurement data column and the data column accurately measured with an oscilloscope, use the Pearson correlation coefficient to describe the correlation between the two data columns, and obtain the sample correlation coefficient, the first laser sparking interval coefficient r1=0.50, the second laser sparking interval coefficient r2=0.52. According to the three-level division rule, when 0.4≤|r|<0.7, the two variables are significantly correlated. In order to compensate the original data, it is necessary to find a suitable Δ value to minimize the residual sum of squares of the measured column data after compensation. The mathematical model is developed and solved for the nonlinear system of equations, and the optimal value of Δ for the original data is obtained using a global search for the optimal value: Δ1= 0.238μs, Δ2= 0.201μs. Comparing the compensated data with the original data, The standard deviation of the measured columns of the first flash interval decreased from 0.117μs to 0.022μs after compensation, and the second decreased from 0.102μs to 0.014μs. This shows that the two columns error of compensated data are significantly reduced, which is important for the improvement of the velocity measurement accuracy of the target channel.

Timing control of impulse self balancing latch opening of expansion wave gun

Aiming at the problem of accurate latch opening control of expansion wave gun automatic gun, the mathematical model of accurate latch opening time is established, the travel curve of projectile and expansion wave, the velocity curve of projectile and expansion wave are studied, and the occurrence time of expansion wave and the time close to projectile are simulated and analyzed; The time-space evolution relationship between expansion wave velocity and local sound velocity, projectile velocity and gas velocity is simulated; The average pressure time curve and chamber resultant force curve of the two launch modes are compared and analyzed. After the projectile moves for 2.7ms, the chamber pressure and chamber resultant force of expansion wave launch are significantly reduced; The dynamic model of inertial latch opening is established; The changes of projectile initial velocity and recoil force under different latch opening times are studied. The test shows that the recoil force and recoil distance are greatly reduced when the projectile initial velocity decreases very weakly, which shows that the simulation calculation of latch opening time is accurate.

A fast calculation model for interior ballistics simulation of a recoilless launch system with high chamber pressure

Recoilless launch system is economical and convenient. This paper provided a recoilless launch system with high chamber pressure based on the theory of recoilless gun. A program for interior ballistics simulation of the launch system based on the mixed propellent was designed. The curves of chamber pressure and projectile velocity on time and projectile travels were provided by the program. And the phenomena of different combustion stages presented by the curve are discussed. The simulation results reached the set indicators, and it was consistent with the actual interior ballistics. The designed model has certain reference value for real-time simulation and fast computation.

Penetration behavior of reactive projectiles impacting TC4 plates

The reactive projectile presents a tremendous potential to induce the combined damage effect of kinetic energy and chemical energy to the plate. A series of ballistic impact experiments and numerical simulation studies were carried out to study the penetration behavior of reactive projectile against TC4 plate. The experimental results showed that with the impact velocity of the reactive projectile increasing from 537m/s to 682m/s, the damage mode of the plate gradually changes from bulge, cross crack to plug. According to the experimental results, the ballistic limit velocity of reactive projectile perpendicular penetrating 5mm TC4 is 648.33m/s. The numerical simulation results showed that the reactive projectile reaches GPa high pressure within a few microseconds when it impacted with the plate. During reactive projectile penetrating TC4 plate, the chemical energy release significantly improves the projectile penetrating ability, and the contribution of chemical energy to projectile penetrating can reach 55.07%.

A new material model for concrete subjected to high rate of loading

This study presents a modified HJC model for simulating the constitutive behaviour of concrete under large strains, high strain rate and high pressure. The original HJC model has been modified by introducing the shear cracking, pore crushing, tensile cracking, and hydrostatic expansion damage models to the yield surface for reproducing the crushing, spalling (crater formed at the front surface), scabbing (crater formed at the rear surface), and radial cracking in the concrete target. The Lode-Angle model has been introduced to describe the yield surface to account for the substantial difference in the shear strength between the tensile and compressive meridians. The strain rate effect has been considered to suitably model the dynamic compressive and tensile strengths. Single element simulations have been performed to substantiate the effect of modifications introduced in the constitutive model. The results of the single element simulation obtained by using the proposed model (MHJC_K&I) have been compared with the results of the two latest modified (MHJC_Kong [1] and MHJC_Liu [2]) models available in the literature. The MHJC_K&I model has described more realistic strength softening under uniaxial compression when compared with the experiment results. Further, the MHJC_K&I model has described accurately the magnitude of tensile strength under uniaxial tension in comparison to the other two models. Under hydrostatic tension, the MHJC_K&I model described the exponential strength softening and the MHJC_Kong model described the linear softening while the MHJC_Liu model had limitation in describing the softening behaviour. The ballistic experiments have also been performed on 100 and 60 mm thick plain concrete targets against 0.4 kg steel projectile at incidence velocities in the range 103–220 m/s. The damage induced in the concrete targets as well as the residual projectile velocities have been obtained. The MHJC_K&I model has been found to effectively reproduce the damage with respect to the size and depth of the crater as well as the radial cracking at the front and rear surfaces of the plain concrete target. The MHJC_Kong and MHJC_Liu models underestimated the size and depth of the crater and described limitations in reproducing the radial cracking. The residual velocities obtained by using the proposed model (MHJC_K&I) have been found to have a good agreement with the actual results.

Experimental evaluation of the ballistic resistance of aramid fabrics under near simultaneous multiple fragment impacts

The ballistic resistance of protective equipment against fragment impacts, such as those typically generated from explosions, has been a major concern the past 50years. The simplifications required to investigate the material response to multiple fragment impacts were set based on the technological limitations of the past. Still, current standardised ballistic testing methodologies consider the interactions between multiple impacting fragments negligible, simulating the multiple impulsive loads with single impact tests. This paper challenges this assumption, introducing the parameters of spacing, formation and timing between multiple impacts in a laboratory test method.An in house pyrotechnical triple launcher is designed and implemented which can shoot three 1.102 g Fragment Simulating Projectiles (FSP) with each shot. An add-on dispersion unit allows for adjusting the distances between the impact points. The control over the projectile velocities and the dispersion of the three impact points enables the simulation of a dense fragment cluster impact with specific characteristics. The setup is used to test Aramid dry fabrics against fragmentation. In total 53 specimens of 15 layers of Kevlar 29 plain weave fabrics are tested against single and triple impacts with two different levels of projectile dispersion. The results show a drop in the target's ballistic limit of up to 13% against triple impacts compared to single impact tests. The fabric's ballistic performance seems to improve with increasing the distances between the impact points. For every triple impact test, the parameters: impacting velocity, distances between impact points, alignment of impact points with the warp and weft directions and time intervals between impacting projectiles is documented.

Research on the impact resistance of aluminum alloy circular corrugated sandwich plates against different nose shape projectiles

The impact resistance of aluminum alloy circular corrugated sandwich plate is investigated by using the experiments and simulations, and the influence of projectile nose shape and impact velocity on the failure mode and energy dissipation characteristics is analyzed. The experimental results indicate that the projectile nose shape influences the impact resistance of circular corrugated sandwich plates. The ballistic limit velocity (BLV) and energy dissipation of the plate increase as the caliber radius head (CRH) of the projectile increases, and the failure mode gradually changes from shear plugging damage and tensile tearing damage to ductile hole enlargement and petal cracking damage. Numerical simulation results show that the numerical simulation can accurately predict the ballistic limit velocity, failure mode and the impact process.

Determination of the ballistic performance ramie-fiber-reinforced epoxy composite-sic ceramic in multilayered armor system

Multilayered Armor System (MAS) is being extensively studied around the world for its ability to retain ceramic fragmentation after a collision occurs. MAS consist of a ceramic layer placed at the front and supported by a composite layer of ramie-fiber-reinforced epoxy resin. Present study utilizes natural fibers of 50 % ramie fibers with epoxy resin as the matrix and Silicon Carbide (SiC) ceramic as the front panel. The ballistic testing in this study used 7.62×51 mm NATO Ball projectile with a firing distance of 15 m from the bullet panel. The velocity of projectile was detected using LIGHT SCREEN B471 type. The aim of the study is to conclude the optimal thickness of ramie fiber-epoxy and SiC ceramics MAS structure based on experiments which can withstand 7.62 NATO ball bullet penetration. To achieve this aim, the following objectives are accomplished: study the effect of SiC ceramic addition to ramie composite on BFS and study the effect of SiC ceramic addition to ramie composite on failure mode. Results show that the addition of the number of layers of SiC increases resistance of ballistic MAS marked by a decrease in the value of BFS clay. The 5SiC+10R is the optimal thickness in resisting the penetration of 7.62×51 mm bullets with 12 mm BFS clay. Failure phenomena found in this study were projectile fragments, matrix cracks, radial cracks, impact points, and ceramic fragments. Matrix crack formation appears on 5SiC+10R with mini deformation in rear side. Phenomenon of ceramic fragmentation in the shot causes the MAS structure to be damaged, so that the ramie fiber composite layer will face the bullet directly if it is subjected to a second shot. Ultra High Hardness Armor (UHHA) as first layer on the MAS structure is an attractive option for further research.