Kinetic Energy Of Projectile Research Articles

The effect of impact duration on the axial fracture tolerance of the isolated tibia during automotive and military impacts.

Axial impacts to the lower leg during debilitating events such as frontal automotive collisions and military underbody blasts can cause significant injuries to the tibia. Several studies have conducted axial impact tests to determine the injury limits of the lower leg, mostly focused on automotive intrusions, resulting in an established force criterion for injury assessments. Due to the viscoelastic properties of bone, it remains unclear whether results from automotive experiments can be applied to higher-rate military blasts. Twelve male isolated cadaveric tibias (from six pairs, mean age: 62 ± 8 years) were subjected to axial impact loads using a custom-built pneumatic impactor, with one specimen from each pair tested at velocity and impact durations representative of a military blast condition, and the contralateral under conditions representing an automotive collision. Impacts were applied in increasing levels of intensity (defined using energy levels) until fracture occurred. Fracture risk was influenced by projectile velocity, kinetic energy, impulse, and load rate, and there was a significant difference in peak force (p = 0.023), impulse (p = 0.09), and load rate (p = 0.025) between the automotive and military test conditions causing fracture. A 10% risk of fracture corresponded to an impact force of 9.0kN for the automotive condition and 12.2kN for the military condition. These results suggest that fracture tolerances developed in studies that simulate automotive impacts cannot be directly applied to military impacts of shorter duration. The number of factors identified to predict injury also suggests that fracture is not controlled by a single variable.

High energy ballistic and fracture comparison between multilayered armor systems using non-woven curaua fabric composites and aramid laminates

For personal protection against high kinetic energy projectiles, multilayered armor systems (MAS) are usually the best option. They combine synergistically the properties of different materials such as ceramics, composites and metals. In the present work, ballistic tests were performed to evaluate multilayered armor systems (MAS) using curaua non-woven fabric epoxy composites as second layer. A comparison to a MAS using aramid (Kevlar™) fabric laminates was made. The results showed that the curaua non-woven fabric composites are suitable to the high ballistic applications, and are promising substitutes for aramid fabric laminates.

Temperature and energy effects on secondary electron emission from SiC ceramics induced by Xe17+ ions

Secondary electron emission yield from the surface of SiC ceramics induced by Xe17+ ions has been measured as a function of target temperature and incident energy. In the temperature range of 463–659 K, the total yield gradually decreases with increasing target temperature. The decrease is about 57% for 3.2 MeV Xe17+ impact, and about 62% for 4.0 MeV Xe17+ impact, which is much larger than the decrease observed previously for ion impact at low charged states. The yield dependence on the temperature is discussed in terms of work function, because both kinetic electron emission and potential electron emission are influenced by work function. In addition, our experimental data show that the total electron yield gradually increases with the kinetic energy of projectile, when the target is at a constant temperature higher than room temperature. This result can be explained by electronic stopping power which plays an important role in kinetic electron emission.

A Special Collaborative Information System and Its Application in Kinetic Energy Impact

Although the benefits of the non-lethal kinetic energy projectiles are numerous, there is a need to assess the projectiles to assure their expected functions. In order to overcome the limitations of current research, a special collaborative information system based on Hybrid III 50th percentile male dummy (hybrid III dummy) was developed and validated to assess and predict the risk of non-lethal kinetic energy impact. Two types of non-lethal kinetic energy projectiles were used to attack the thorax region of the dummy surrogate at six levels of distance. Not only the sensors inside the dummy as a mechanics information system recorded all the kinetic energy impact measures accurately and effectively, but also other systems like acquiring and processing information system including hardware and software played their roles respectively. The acceleration response, displacement response showed consistent patterns with the kinetic energy measures. The results showed that the measurement from the special system was reliable for non-lethal kinetic energy projectiles. The maxima of displacement, viscous criterion (VC) and kinetic energy were both lower than correlative injury thresholds. Current study provided an alternative method to assess the performance of the non-lethal kinetic energy projectiles.

ANALYSIS OF ENERGETIC PARAMETERS FOR ANTITANK KINETIC AMMUNITION OF CONTEMPORARY BATTLEFIELD

Basic energetic parameters of select-ed examples of 120 mm APFSDS (armur piercing fin stabilised discarding sabots) service projectiles are specified and analysed in the paper. Author has estimated chances for meeting penetration capacities through RHA (rolled homogeneous armour) by designs of kinetic energy projectiles which are currently under development. The summary also includes a characterisation of present limitations for tank guns ballistic parameters.

Atom–surface scattering: a comparative study considering real and complex absorbing potentials

In this paper a low density atomic gas colliding on a solid surface was modelled using the quantum scattering theory. The surface has discrete trapping/scattering centers in its lattice. In the model, a harmonic potential for the surface atoms interaction and a constant effective mean field for the gas atoms interactions were considered. The projectile atoms were assumed to be interacted with a solid surface atoms by two different potential models: (i) the Morse potential model, which is a real absorbing potential; and (ii) the Scarf II potential, which is a complex absorbing potential. The scattering probability densities for both models were calculated analytically via the first Born approximation. The effect of the incident atom energies as well as the distance of gas atoms from the surface on the probability densities were studied for both real and complex absorbing potentials. Comparisons have been made between these two types of potentials using the Lippmann–Schwinger quantum scattering equation. It was found that in addition to the competition between repulsive and attractive parts of the potentials, the imaginary part of the complex Scarf II potential has a significant effect on the distance of gas atoms from the surface. The adsorption probabilities of incident atoms on the surface considering the Morse model as well as Scarf II potential were obtained analytically as a function of distance from surface and kinetic energy of projectiles. Comparison our calculated adsorption coefficient with the simulation data of isothermal density distribution for nitrogen and argon adsorbed on the graphite surface shows that the maximum adsorption positions for both potential models provide a good agreement with simulation results.

Thermal-mechanical analysis on the mass loss of high-speed projectiles penetrating concrete targets

Abstract The significant mass loss of the kinetic energy (KE) projectile has been observed in the high-speed penetration (usually v0 > 1 km/s) into concrete target, resulting in nose abrasion, bending, and trajectory deviation as well as great drop of the Depth of Penetration (DOP). The thermoplastic failure of material peeling from the thin exterior interface between the projectile and the concrete is the main mechanism of the mass loss. Combining the heat generated from the friction work and the plastic deformation work during the high-speed penetration process, a discrete iterative method is proposed to investigate the movement and the nose shape variation on the basis of thermoplastic instability of the material. Utilizing the temperature-based failure criterion and the Johnson-Cook (J-C) constitutive model, the receding displacements of the discrete points are determined by the gradient distribution of the temperature change along the depth from the surface of a projectile, which result in blunting of the projectile nose. The predictions of the nose shape, the percentage of the mass loss and the DOP were validated against the experimental data. Then further studies are conducted to investigate the critical velocity of mass loss and the “secondary peak” deceleration. The onset of the mass loss and the occurrence of the distinct pulse of the deceleration in the tunnel stage are regarded as the symbol of the lower and upper velocity limits of the nondeformable penetration regime. In addition, through the comparison of the percentages of heat generated with different mechanisms at different locations of the projectile, the dominant mechanism of the mass loss between the friction and plastic deformation is analyzed to get an insight into the high-speed penetration process.

Energy Transfer Efficiency Optimization in an Electromagnetic Railgun

Electromagnetic railguns (EMRs) launch projectiles by the systematic triggering of current pulse forming units (PFUs), which release stored capacitor energy. Past work has focused on maximizing projectile velocity at the muzzle for given PFU capacitor charge voltages, which maximizes efficiency. However, operators in naval applications need to be able to select the muzzle velocity for a projectile to achieve a desired ballistic path. Thus, there is a demand to maximize efficiency for a given muzzle velocity. As such, this paper investigates maximizing the efficiency of transferring the stored PFU capacitor electrical energy to projectile kinetic energy while minimizing the current value when the projectile exits the rails to reduce damage to them from arcing. This is accomplished by optimizing the choice of the initial capacitor voltage in each PFU and the trigger timing subject to an electrical-mechanical dynamic model of the EMR and projectile and any additional scenario constraints (described shortly). This optimization is solved using numerical programming in the context of a relaxation with the initial capacitor voltages and triggering times as the only explicit variables to the optimizer; additional needed values are obtained from a differential algebraic equation solver. The optimization is successfully demonstrated for three scenarios: operation for a projectile mass and muzzle velocity associated with published operating parameters, operation for several projectile mass-muzzle velocity pairs with both equal and distinct initial capacitor voltages, and operation for several projectile mass-muzzle velocity pairs with a load current bound and equal initial capacitor voltages. Results show improved efficiency in comparison to the use of the published parameters, the independence of efficiency from projectile mass when there is no current bound, virtually identical results for equal and distinct initial capacitor voltages, and decreased efficiency with a current bound.

Retraction Note to: Multi-Length Scale Analysis of the Effect of Fused-Silica Pre-shocking on its Tendency for Devitrification

Recent studies have suggested that impact-induced devitrification of fused silica, or more specifically formation of high-density stishovite, can significantly improve ballistic-penetration resistance of fused silica, the material which is used in transparent armor. The studies have also shown that in order for stishovite to form during a ballistic impact event, very high projectile kinetic energy normalized by the projectile/fused-silica target-plate contact area must accompany such an event. Otherwise fused-silica devitrification, if taking place, does not substantially improve the material ballistic-penetration resistance. In the present work, all-atom molecular-level computations are carried out in order to establish if pre-shocking of fused-silica target-plates (to form stishovite) and subsequent unloading (to revert stishovite to the material amorphous structure) can increase fused silica’s propensity for stishovite formation during a ballistic impact. Towards that end, molecular-level computational procedures are developed to simulate both the pre-shocking treatment of the fused-silica target-plate and its subsequent impact by a solid right-circular cylindrical projectile. The results obtained clearly revealed that when strong-enough shockwaves are used in the fused-silica target-plate pre-shocking procedure, the propensity of fused silica for stishovite formation during the subsequent ballistic impact is increased, as is the associated ballistic-penetration resistance. To rationalize these findings, a detailed post-processing microstructural analysis of the pre-shocked material is employed. The results obtained suggest that fused silica pre-shocked with shockwaves of sufficient strength retain some memory/embryos of stishovite, and these embryos facilitate stishovite formation during the subsequent ballistic impact.

Projectile penetration into mortar targets with a broad range of striking velocities: Test and analyses

Eighteen shots of flat nosed cylindrical 45# steel projectiles penetrating into mortar targets with cubic compressive strength of 50MPa are conducted, where the striking velocities are ranged from 510m/s to 1850m/s. By examining the damages of targets, linear dependences of the cratering diameter and depth on the initial striking velocity, as well as the cratering volume on the initial kinetic energy of projectile are found. Three penetration regimes, i.e., rigid projectile penetration, deforming projectile penetration without eroding and eroding projectile penetration are observed successively with the increase of striking velocity. Furthermore, the experimental depths of penetration are compared with the predictions of our recently established rigid and eroding penetration models based on an extended dynamic cavity expansion model (Kong et al. 2017). The rigid projectile penetration model is further validated, and the eroding projectile penetration model is further justified, improved and validated by considering the succeeding rigid penetration stage. Finally, the analytical expressions for the upper limit velocity of rigid projectile penetration and the lower limit velocity of eroding projectile penetration are given and validated, respectively.

Projectile Penetration into Sandy Soil Confined by a Honeycomb-Like Structure

HPS (Honeycomb-like Protective Structure) is a newly proposed protective structure filled with sandy soil. In order to investigate the penetration resistance of the structure, numerical simulations based on SPH method had been carried out by using LS-DYNA, which are corresponding to the experiments. The calibrated model leads to reasonable predictions of the dynamic responses and damage modes of the HPS. More situations were carried out taking factors influencing the penetration into consideration, including point of impact, angle of impact, and projectile caliber. Penetration mode was established by analyzing the energy dissipation and investigating the mechanism from the phenomenological viewpoint. Simulation results show that the resisting forces and the torque that act on the long rod projectile would be greater than those acting on the short one when instability occurred. Besides, approximate 45° angle of impact was formed in the case of off-axis, which has a certain influence on the ballistic stability, resulting in more kinetic energy of projectile dissipating in HPS and less depth of penetration. The kinetic energy of projectile dissipated in sandy soil largely and the strip slightly, and the former was greater than the sum of the latter.

Stopping dynamics of ions passing through correlated honeycomb clusters

A combined nonequilibrium Green functions--Ehrenfest dynamics approach is developed that allows for a time-dependent study of the energy loss of a charged particle penetrating a strongly correlated system at zero and finite temperatures. Numerical results are presented for finite inhomogeneous two-dimensional Fermi-Hubbard models, where the many-electron dynamics in the target are treated fully quantum mechanically and the motion of the projectile is treated classically. The simulations are based on the solution of the two-time Dyson (Keldysh-Kadanoff-Baym) equations using the second-order Born, third-order, and $\mathrm{T}$-matrix approximations of the self-energy. As application, we consider protons and helium nuclei with a kinetic energy between 1 and 500 keV/u passing through planar fragments of the two-dimensional honeycomb lattice and, in particular, examine the influence of electron-electron correlations on the energy exchange between projectile and electron system. We investigate the time dependence of the projectile's kinetic energy (stopping power), the electron density, the double occupancy, and the photoemission spectrum. Finally, we show that, for a suitable choice of the Hubbard model parameters, the results for the stopping power are in fair agreement with ab initio simulations for particle irradiation of single-layer graphene.

Enhancement the Armor Shielding Properties of CF/epoxy Composite by Addition Nanoparticles of Magnetic Iron Oxide

In the present investigation, we prepared two types of CF composites. The first prepared composite sample was CF/epoxy resin composite and the second was CF/epoxy resin / with a different weight ratio of magnetic iron oxide. Magnetic iron oxide was prepared by co-precipitation method, with particle sizes measured in range 25:35 nm. The resistance to penetration of high kinetic energy projectile of the prepared composite sample was measured and It was found that addition of 5% nano-particles of magnetic iron oxide to composite material sample decrease the residual velocity of projectile penetrating it by 9%.i.e increasing resistance of the sample to penetration of high kinetic energy projectile.it was found that the Resistance to penetration of sheet of composite material sampleC4 of weight=40.32kg to projectile 7.62×39 mm AP at distance 15m equivalent to resistance of steel sheet of weight =54.6 kg at distance 200m.Resistance to penetration of sheet of composite material sampleC4 to projectile 7.62×39 mm AP at distance 10m equivalent to the resistance of high-quality steel sheet(steel4340) of weight=47.85 kg at distance 25m.

FEATURES OF CRIMINALISTIC RESEARCH OF BALLISTIC CHARACTERISTICS AND STRIKING PROPERTIES OF ELASTIC BUCKSHOT OF TRAUMATIC EFFECT CARTRIDGES “TEREN-12K”

During experimental studies of ballistic characteristics and elastic buckshot killability of 12-caliber cartridges "Teren-12K" of traumatic action, the de nition was given to peculiarities of buckshot kinetic energy dispersion on the trajectory as well as to the nature of impact-contact interaction with biological object tissues at various ranges of shooting. Particular attention was paid to the examination of elastic buckshot killability at shooting ranges, for which the compact action of such a multiple kineticenergy projectile is typical. The complex of differential diagnostic features is determined for buckshot shooting at close ranges.

RETRACTED ARTICLE: Multi-Length Scale Analysis of the Effect of Fused-Silica Pre-shocking on its Tendency for Devitrification

Recent studies have suggested that impact-induced devitrification of fused silica, or more specifically formation of high-density stishovite, can significantly improve ballistic-penetration resistance of fused silica, the material which is used in transparent armor. The studies have also shown that in order for stishovite to form during a ballistic impact event, very high projectile kinetic energy normalized by the projectile/fused-silica target-plate contact area must accompany such an event. Otherwise fused-silica devitrification, if taking place, does not substantially improve the material ballistic-penetration resistance. In the present work, all-atom molecular-level computations are carried out in order to establish if pre-shocking of fused-silica target-plates (to form stishovite) and subsequent unloading (to revert stishovite to the material amorphous structure) can increase fused silica’s propensity for stishovite formation during a ballistic impact. Towards that end, molecular-level computational procedures are developed to simulate both the pre-shocking treatment of the fused-silica target-plate and its subsequent impact by a solid right-circular cylindrical projectile. The results obtained clearly revealed that when strong-enough shockwaves are used in the fused-silica target-plate pre-shocking procedure, the propensity of fused silica for stishovite formation during the subsequent ballistic impact is increased, as is the associated ballistic-penetration resistance. To rationalize these findings, a detailed post-processing microstructural analysis of the pre-shocked material is employed. The results obtained suggest that fused silica pre-shocked with shockwaves of sufficient strength retain some memory/embryos of stishovite, and these embryos facilitate stishovite formation during the subsequent ballistic impact.

On the universal scaling in the electronic stopping cross section for heavy ion projectiles

ABSTRACTEnergy deposition of heavy ions when penetrating a material is of crucial importance in determining the damage to materials with implications in areas such as material science, plasma physics, radiotherapy and dosimetry. Due to the N-body electron problem, it has been thought that the electronic stopping cross section is unique for a given projectile–target combination and differs from system to system. In this work, we show that within the Bethe theory, there is a universal scaling when the electronic stopping cross sections and projectile kinetic energy are scaled properly in terms of the target mean excitation energy, , for all projectile–target combinations. We show that the scaling is given by as a function of , thus showing the importance of the characterization of the mean excitation energy. The scaling law expresses a systematic and universal behavior among complex projectile–target systems in the energy deposition, characterized by the minimum momentum transfer during the slowing down process. We provide an analytic expression for the universal scaling law for the stopping cross section of any projectile–target combination valid at high collision energies. Finally, we verify the universal scaling law by comparison to atomic and molecular experimental data available in the literature. We expect our findings will motivate further experimental work to verify our universal scaling for more complex systems in the absence of experimental data.

Hazard zoning for volcanic ballistic impacts at El Chichón Volcano (Mexico)

The 1982 eruption of El Chichon Volcano in southeastern Mexico had a strong social, economic, and environmental impact. The eruption gave rise to the most disastrous volcanic events in Mexico, killing around 2000 inhabitants, displacing thousands, and resulting in severe economic losses. Despite some villages were relocated after this eruption, many people still live and work in the vicinities of the volcano and might be affected in the case of a new eruption. For this reason, it is important to identify the exposed zones. The published hazard map of El Chichon Volcano covers pyroclastic flows and surges, lahars, and ashfall, but not ballistic projectiles, which would represent an important threat in the case of an eruption. In fact, the fatalities reported in the first stage of the 1982 eruption were caused by ballistic projectiles and ashfall that induced roof collapse. In this study, the hazard zones for volcanic ballistic projectiles at El Chichon Volcano are delimited through a general methodology that has been applied to other volcanoes such as Popocatepetl (Alatorre-Ibarguengoitia et al. in Bull Volcanol 74:2155–2169, 2012. doi:10.1007/s00445-012-0657-2) and Colima (Alatorre-Ibarguengoitia et al. in Geol Soc Am Spec Paper 402:26–39, 2006). The maximum launching kinetic energy of projectiles identified in the field corresponding to past eruptions is reconstructed by using a ballistic model. These energies are then used to parameterize different explosion scenarios that can occur in the future. The maximum ranges expected for the projectiles in the different explosive scenarios defined for El Chichon Volcano are presented in a ballistic hazard map which complements the published hazard map. The responsible authorities may use this map to be able to mark off the restricted zones during volcanic crises.

The effect of fused-silica pre-shocking on its devitrification propensity and ballistic resistance: an all-atom molecular-level analysis

Recent studies have suggested that impact-induced devitrification of fused silica, or more specifically formation of high-density stishovite, can significantly improve ballistic-penetration resistance of fused silica, the material which is used in transparent armor. The studies have also shown that in order for stishovite to form during a ballistic-impact event, very high projectile kinetic energy normalized by the projectile/fused-silica target-plate contact area must accompany such an event. Otherwise fused-silica devitrification, if taking place, does not substantially improve the material ballistic-penetration resistance. In the present work, all-atom molecular-level computations are carried out in order to establish if pre-shocking of fused-silica target-plates (to form stishovite) and subsequent unloading (to revert stishovite to the material amorphous structure) can increase fused silica’s propensity for stishovite formation during a ballistic impact. Towards that end, molecular-level computational procedures are developed to simulate both the pre-shocking treatment of the fused-silica target-plate and its subsequent impact by a solid right-circular cylindrical projectile. The results obtained clearly revealed that when strong-enough shockwaves are used in the fused-silica target-plate pre-shocking procedure, the propensity of fused silica for stishovite formation during the subsequent ballistic impact is increased, as is the associated ballistic-penetration resistance. To rationalize these findings, a detailed post-processing microstructural analysis of the pre-shocked material is employed. The results obtained suggest that fused silica pre-shocked with shockwaves of sufficient strength retain some memory/embryos of stishovite, and these embryos facilitate stishovite formation during the subsequent ballistic impact.

The Efficiency of Ultra-High Molecular Weight Polyethylene Composite Against Fragment Impact

This paper presents an experimental investigation into the ballistic resistance of ultra-high molecular weight polyethylene (UHMW-PE) composite, and compares its performance against a range of common metallic and composite armour materials. An extensive experimental program was conducted to determine the ballistic limit velocity (V50) of UHMW-PE composite against 12.7 and 20 mm fragment simulating projectiles (FSPs) for a wide range of thicknesses. For protection against these projectiles, UHMW-PE composite was found to be consistently more mass efficient than rolled homogeneous armour steel (RHA), high hardness armour steel (HHA), aluminium alloy 5059-H131, and polymer composites reinforced with aramid, glass or carbon fibres. In terms of armour space claim, UHMW-PE composite was found to be less efficient than both steel types and glass fibre-reinforced plastic, though it was comparable to aramid fibre-reinforced plastic, and was more efficient than aluminium 5059-H131 and carbon fibre-reinforced plastic. Scaling effects were observed that showed metals were more effective against smaller projectiles in terms of armour mass required to stop a given projectile kinetic energy. These effects were not observed to the same extent for UHMW-PE composite, giving rise to a higher UHMW-PE mass efficiency against larger projectiles.

Overcoming the structural versus energy dissipation trade-off in highly crosslinked polymer networks: Ultrahigh strain rate response in polydicyclopentadiene

Abstract Ballistic performance, at effective strain rates of (10 4 –10 5 s −1 ), for polymeric dicyclopentadiene (pDCPD) was compared with two epoxy resin/diamine systems with comparable glass transition temperatures. The high rate response was characterized in terms of a projectile penetration kinetic energy, KE 50 , which describes the projectile kinetic energy at a velocity with a 50% probability of sample penetration. pDCPD showed superior penetration resistance, with a 300–400% improvement in ballistic energy dissipation, when compared with the structural epoxy resins. In addition, unlike typical highly crosslinked networks that become brittle at low temperatures, the improved pDCPD performance occurred over a very broad temperature range (−55 to 75 °C), despite exhibiting a glass transition temperature characteristic of structural resins (∼142 °C). In addition to the high T g , pDCPD exhibited a room temperature glassy storage modulus of 1.7 GPa, offering the potential to circumvent the common structural versus energy dissipation trade-off encountered with conventional crosslinked polymers. Quasi-static measurements suggested that the performance of pDCPD is phenomenologically related to higher fracture toughness and lower yield stress relative to typical epoxies, while molecular dynamics simulations suggest the origin is the lack of strong non-covalent interactions and the facile formation of nanoscale voids to accommodate strain in pDCPD.