Kinetic Energy Of Projectile Research Articles

Theoretical study on penetration of closed cell aluminium foams by truncated cone nosed projectiles

In this paper, the mechanical behaviour of closed cell aluminium foams against truncated cone nosed projectile penetration is studied theoretically. An analytical model based on dynamic cavity expansion theory and previous experiment data is presented. The analytical equations are derived for the penetration resistance and the velocity during the whole penetrating process. The effects of the mass density of target material, the geometry and initial velocity of the projectiles on the final penetration depth are investigated in detail. It is shown that the final penetration depth mostly lies on the density of aluminium foams and the kinetic energy of projectiles. On the basis of the model, instantaneous state of the projectiles can be predicted.

Characterization of 6061 T651 aluminum plates subjected to high-velocity impact loads

Ballistic response of single or multi-layered metal armor systems subjected to kinetic energy projectiles was investigated in many experimental, theoretical and numerical studies. In this study, 6061 T651 aluminum plates impacted by 9 mm bullets were investigated. Microstructural investigations have been carried out using optical microscopy. Microhardness values were used to determine the strength behavior of the plates. Influence of the plate thickness and impact velocity on the microstructure has been evaluated. It was concluded from the study that thinner plates are more prone to deformation hardening with high penetration depth values even at low impact velocities while thick plates are more susceptible to thermal softening with less penetration depths. Maximum hardness values were obtained just below the impact zone in both plate thicknesses.

A Numerical Research on the Penetration into a Semi-Infinite Rolled Homogeneous Armor by a Medium-Caliber Kinetic Energy Projectile

This paper presents numerical analysis on the penetration into a semi-infinite Rolled Homogeneous Armor(RHA) steel target by a medium-caliber projectile at the velocity range from 900m/s to 1000m/s. The projectile was made of a 93% tungsten heavy alloy(WHA) having a diameter of 18mm. LS-DYNA, an explicit non-linear finite element analysis code, was used for the numerical analysis. This kind of penetration problem is generally accompanied by large deformation, high strain rate and thermal softening, accordingly the Johnson-Cook constitutive models combined with Johnson-Cook fracture model and Mie-Gruneisen equation of state were employed to describe the RHA target and the WHA projectile, respectively. Due to the lack of the parameters of the Johnson-Cook failure model of RHA, the corresponding data of 4340 steel were applied for RHA inevitably. Here, two different failure strains for 4340 steel from the literatures were substituted in for RHA and their effects on the numerical analysis results were discussed and compared to the test results in terms of penetration efficiency(P/L) and crater hole shape. A quarter parts of the semi-infinite RHA target and the WHA projectile were only modeled considering the symmetric configuration of the problem for the analysis.

Experimental study on static and impact strength of sintered agglomerates

Porous internal structure is common among small bodies in the planetary systems and possible range of porosity, strength, and scale of in-homogeneity is wide. Icy agglomerates, such as icy dust aggregates in the proto-planetary disks or icy re-accumulated bodies of fragments from impact disruption beyond snow-line would have stronger bulk strength once the component particles physically connect each other due to sintering. In this study, in order to get better understanding of impact disruption process of such bodies, we first investigated the critical tensile (normal) and bending (tangential) forces to break a single neck, the connected part of the sintered particles, using sintered dimer of macro glass particles of ∼5 mm in diameter. We found that the critical tensile force is proportional to the cross-section of the neck when the neck grows sufficiently larger than the surface roughness of the original particles. We also found that smaller force is required to break a neck when the force is applied tangentially to the neck than normally applied. Then we measured the bulk tensile strength of sintered glass agglomerates consisting of 90 particles and showed that the average tensile stress to break a neck of agglomerates in static loading is consistent with the measured value for dimers. Impact experiments with velocity from 40 to 280 m/s were performed for the sintered agglomerates with ∼40% porosity, of two different bulk tensile strengths. The size ratio of the beads to the target was 0.19. The energy density required to catastrophically break the agglomerate was shown to be much less than those required for previously investigated sintered glass beads targets with ∼40% porosity, of which the size of component bead is 10 −2 times smaller and the size ratio of the bead to target is also ∼10 −2 times smaller than the agglomerates in this study. This is probably due to much smaller number of necks for the stress wave to travel through the agglomerates and therefore the energy dissipation at the necks is minimal. Also, the much larger fraction of the surface particles enables the particles to move more freely and thus be broken more easily. The catastrophic disruption of the agglomerates is shown to occur when the projectile kinetic energy is a few times of the total energy to break all of the necks of the agglomerates. The result implies that finer fragments from sintered agglomerates may have smaller catastrophic disruption energy threshold for shattering ( Q S ∗ ) than other larger fragments with similar porosity and bulk tensile strength but much larger number of constituent particles. If this is the case, size-dependence of Q S ∗ (smaller is weaker) is opposite to those usually considered for the bodies in the strength regime.

Mechanical Behaviours of Open-Cell and Closed-Cell Aluminium Foams against Spherical-Nosed Projectile Penetration

In this paper, the mechanical behaviours of open-cell and closed-cell aluminium foams against spherical-nosed projectile penetration are studied theoretically. An analytical model based on dynamic cavity expansion theory and previous experiment data is presented. The analytical equations are derived for the penetration resistance and the final penetration depth during the whole penetrating process. The effects of the mass density of target material, the geometry and initial velocity of the projectiles on the final penetration depth are investigated in detail. It is shown that the final penetration depth mostly lie on the density of aluminium foams and the kinetic energy of projectile. When the density of target is smaller, the final penetration depth of projectile in the closed-cell aluminium foams target is obviously smaller than that in the open-cell aluminium foams target. Meanwhile, with the increase of density of target and the decrease of initial impact velocity, the difference of the capacity of absorbing energy between open-cell and closed-cell aluminium foams targets becomes gradually narrow.

Impact sensitivity of intermetallic nanocomposites: A study on compositional and bulk density

High density intermetallic nanocomposites are being considered as a replacement for kinetic energy projectiles in ordnance applications. These composites release a large amount of chemical energy upon penetration and provide an enhanced blast effect on the target; in comparison to inert projectiles. A fundamental understanding of the response to mechanical initiation as a function of the composite’s compositional and bulk density are presented for aluminum-based intermetallics. Composites ranged in compositional density from 3.5 to 17.9 g/cc and included Al-Ti, Al-Ni, Al-W, Al-Hf, Al-Zn pressed to bulk densities that ranged from 50 to 80% of the theoretical maximum. Aluminum particle size was also investigated and ranged from nanometer to micron-scale spherical diameters. Ignition was stimulated via a modified type 12 impact tester used to measure the sensitivity of the composite to drop weight impact. The tests were recorded using high-speed thermal imaging to ensure a positive reaction. Results show that the nano Al particle composites are more sensitive to impact ignition than their micron scale counterparts. As bulk density increases, the samples become increasingly sensitive to ignition and display an average 70% decrease in ignition energy. Compositional density also plays a critical role in ignition energy. As the density of the composite increases, regardless of the Al particle size, the composites become more sensitive to ignition. Results show that at the same bulk density, higher compositional density composites such as Al-W require 80% less ignition energy than lower compositional density composites such as Al-Ti (1.01 cm compared with 0.34 cm, respectively).

Effect of projectile hardness on deformation and fracture behavior in the Taylor impact test

The ballistic perforation performance of a kinetic energy projectile would be much more influenced by the projectile’s deformation during the impact process. A projectile may suffer from large deformation and even fracture as more and more advanced materials are used as resistant components. A comparison investigation was presented in this study concerning the deformation and fracture behavior of kinetic energy projectiles manufactured from 38CrSi steel of two different hardness values. Flat-nosed projectiles were fired in a two-stage compressed gun test facility against hard steel plates within the velocity range of 200–600 m/s. The impact process was monitored by a high-speed camera. Experimental results showed that, for the soft projectiles there are three deformation and fracture modes, i.e., mushrooming, shear cracking and petalling, and that for the hard projectiles there are also three modes, mushrooming, shearing cracking and fragmentation.

Trauma potential and ballistic parameters of cal. 9 mm P.A. dummy launchers

Introduction Blank cartridge actuated dummy launching devices are used by migratory bird hunters to train dogs to retrieve downed birds. The devices create a loud noise while simultaneously propelling a hard foam dummy for retrieval. A newly developed dummy launcher is based on a modified cal. 9 mm P.A. blank handgun with an extension tube pinned and welded to the barrel imitation. Currently, there are no experimental investigations on the ballistic background and trauma potential of these uncommon shooting devices. Methods An experimental test set-up consisting of a photoelectric infrared light barrier was used for measurement of the velocity of hard foam dummies propelled with an automatic dummy launcher. Ballistic parameters of the dummies and an aluminium sleeve as improvised projectile (kinetic energy ( E), impulse ( p), energy density ( E′) and threshold velocity ( v tsh ) to cause penetrating wounds as a function of cross-sectional density ( S)) were calculated. Results The average velocity ( v ) of the dummies was measured 25.71 m/s exerting an average impulse ( p) of 3.342 Ns. The average kinetic energy ( E) was calculated 43.04 J with an average energy density ( E′) of 0.069 J/mm 2. The average velocity ( v ) of the aluminium sleeves as improvised projectiles was measured 79.58 m/s exerting an average impulse ( p) of 2.228 Ns. The average kinetic energy ( E) of the aluminium sleeves was calculated as 88.70 J with an average energy density ( E′) of 0.282 J/mm 2. Conclusion The energy delivered by these shooting devices is high enough to cause relevant injuries. The absence of skin penetration must not mislead the emergency physician or forensic expert into neglecting the potential damage from these devices.

Slow highly charged ions induced electron emission from clean Si surfaces

The electron emission yields from the interaction of slow highly charged ions (SHCI)He2+,O2+and Ne2+ with clean Si surface are measured separately. It is found that electron emission yield γ increases proportionally to projectile kinetic energy EP/MP ranging from 0.75 keV/u to 10.5 keV/u (i.e. 3.8×105 m/s≤vP≤ 1.42×106 m/s), and it is higher for heavy ions (O2+and Ne2+) than for light ion (He2+). For O2+and Ne2+, γ increases with ZP decreasing in our energy range, and it shows quite different from the result for higher projectile kinetic energy. After calculating the stopping power by using TRIM 2006, it is found that the fraction of secondary electrons induced by recoil atoms increases significantly at lower projectile energy, thereby leads to the differences in γ for heavy ions O2+and Ne2+between lower and higher projectile kinetic energy.

Modelling of composite sandwich structures with honeycomb core subjected to high-velocity impact

In this study the perforation of composite sandwich structures subjected to high-velocity impact was analysed. Sandwich panels with carbon/epoxy skins and an aluminium honeycomb core were modelled by a three-dimensional finite element model implemented in ABAQUS/Explicit. The model was validated with experimental tests by comparing numerical and experimental residual velocity, ballistic limit, and contact time. By this model the influence of the components on the behaviour of the sandwich panel under impact load was evaluated; also, the contribution of the failure mechanisms to the energy-absorption of the projectile kinetic energy was determined.

Computational Technique to Assess Warhead Lethality against Ballistic Missile

This paper addresses a computational procedure to assess the lethality of kinetic energy projectile warheads against tactical ballistic missile payloads with an innovative and rational damage metric. The individual lethality of different projectile geometries impacting at hypervelocity at different configurations is estimated via a numerical damage index computed from hydrocode simulations. The highest count of possible impacts to the payload is achieved by optimizing the warhead’s configuration and time of detonation, a priori knowledge of the target’s location and speed. The total damage to the payload characterizes the warhead’s lethality for the particular engagement conditions. An example shows the application of the process and potential advantages.

Size modification of Au nanoparticles induced by slow highly charged ions 40Arq+ irradiation

Abstract Size modification of Au nanoparticles (NPs), deposited on the Au-thick film surface and irradiated by slow highly charged ions (SHCI) 40Arq+ (3 ⩽ q ⩽ 12) with fixed low dose of 4.3 × 1011 ions/cm2 and various energy ranging from 74.64 to 290.64 keV at room temperature (293.15 K), was investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). The effect of projectile kinetic energy on the modified size of NPs was explored by an appropriate choice of the fixed process parameters such as ion flux, irradiation temperature, incident angle, irradiation time, etc. The morphological changes of NPs were interpreted by models involving collisional mixing, Ostwald ripening (OR) and inverse Ostwald ripening (IOR) of spherical NPs on a substrate. A critical kinetic energy as well as a critical potential energy of the projectile in the Au NPs size modification process were observed.

Analytical modelling of high velocity impacts of cylindrical projectiles on carbon/epoxy laminates

In this work an analytical model has been developed in order to predict the residual velocity of a cylindrical steel projectile, after impacting into a woven carbon/epoxy thin laminate. The model is based in an energy balance, in which the kinetic projectile energy is absorbed by the laminate through three different mechanisms: linear momentum transfer, fiber failure and laminate crushing. This last mechanism needs the quantification of the through-thickness compressive strength, which has been evaluated by means of quasi-static punch tests. Finally, high velocity impact tests have been accomplished in a wide range of velocities, to validate the model.

A numerical investigation of the influence of yarn-level finite-element model on energy absorption by a flexible-fabric armour during ballistic impact

A series of transient non-linear dynamic finite-element method (FEM) analyses pertaining to the interaction of a single-ply plain-woven balanced square textile-fabric armour with a spherical steel projectile is carried out in order to compare the corresponding results obtained for two different yarn models: (a) a solid FEM model in which the warp and weft yarns are represented using first-order three-dimensional solid elements and (b) a membrane model in which the same yarns are represented using second-order membrane elements. The analyses are carried out under different yarn—yarn and projectile—fabric frictional conditions and under different far-field boundary conditions applied to the edges of the fabric. The results obtained showed that the two sets of analyses yield comparable predictions regarding the temporal evolution and the spatial distribution of the deformation and damage fields within the fabric, regarding the ability of the fabric to absorb the projectile's kinetic energy and regarding the relative contributions of the main energy absorbing mechanisms. The work also confirmed the roles yarn—yarn and projectile—fabric friction play in the impact process as well as the effect of the far-field boundary conditions applied to the edges of the fabric.

Analysis of failure of add-on armour for vehicle protection against ballistic impact

The deployment of peacekeeping forces in conflict areas has shown that some armour systems are not sufficient to meet the latest threats. This applies particularly to lightweight vehicles whose armours give protection only against low calibre ammunitions. The development, production and fielding of add-on armours gives the answers to the demand for mission adjustable protection systems. Add-on armours represent a new protection philosophy, because they are produced as a separate kit, designed to achieve different protection levels. They have several advantages: Separate transport of armour and vehicle, they can be screwed to the main skull structure by crews and they are easily repairable or upgraded. Advanced add-on armours are produced by a clever combination of ceramic tiles backed by metal or composite plates. The utilization of advanced ceramics began in the 1960s when the US Army was demanding lightweight body armours for helicopter crews. Nowadays a wide spectrum of advanced ceramics is currently used for armour production, including alumina, silicon carbide, titanium diboride and boron carbide. Ceramics possess a high protection potential due a moderate density combined to a high compressive strength. But they are too brittle to be used without a ductile material backing. The design of ceramic add-on armours is a difficult task due to the high number of parameters involved: material selection, thicknesses of different materials, impact obliquity, etc. A design based exclusively on experimental tests is therefore expensive in money and time. This paper summarizes the utilization of analytical and numerical computation of ceramic/metal and ceramic/composite add-on armour failure process as valuable tools for armour design optimisation. Some examples are presented showing a good agreement between analytical, numerical and experimental results of residual mass and residual velocity of kinetic energy projectiles after perforation of the add-on armour.

X-ray spectra induced by slow highly charged Ar q+ ions in collision with Nb surface

The X-ray spectra of Nb surface induced by Arq+ (q = 16,17) ions with the energy range from 10 to 20 keV/q were studied by the optical spectrum technology. The experimental results indicate that the multi-electron excitation occurred as a highly charged Ar16+ ion was neutralized below the metal surface. The K shell electron of Ar16+ was excited and then de-excited cascadly to emit K X-ray. The intensity of the X-ray emitted from K shell of the hollow Ar atom decreased with the increase of projectile kinetic energy. The intensity of the X-ray emitted from L shell of the target atom Nb increased with the increase of projectile kinetic energy. The X-ray yield of Ar17+ is three magnitude orders larger than that of Ar16+.

Micrometeoroid impact on ceramic thin components for interplanetary probe

Abstract A new advanced ceramic thruster made of monolithic silicon nitride (Si3N4) is under development for the next interplanetary probe of PLANET-C Venus exploration mission in Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA). In order for secure operation of a spacecraft with a ceramic component onboard a real mission, the reliability against micrometeoroid impacts on the ceramic component has to be investigated in addition to the quasi-static mechanical and thermal analyses and verifications. First, the risk probability of the micrometeoroid impacts was evaluated by using an interplanetary flux model, and the risk evaluation in terms of impact energy was proposed by combining the velocity distribution with the flux model. The probability of impacts on the ceramic thruster during the mission was estimated with this model. Second, hypervelocity impact tests were performed with a two-stage light-gas gun. Three types of failure were observed: one was only a crater formed on the impact surface. Another type was crater formation on the front-face and spall fracture on the back-face and in the last type a perforation was formed in addition to cratering and spalling. The samples did not either shatter or breakdown for the impact energies tested in this study. The impact failure morphology observed in this study showed dependency on the plate thicknesses and the projectile kinetic energy. The energy-based risk evaluation together with the series of the hypervelocity impact tests indicated that the silicon nitride ceramic thruster onboard the interplanetary probe would have only a local damage and survive during the mission term.

3D finite element simulation of sandwich panels with a functionally graded core subjected to low velocity impact

Three-dimensional finite element simulations were conducted for analyzing low velocity impact behavior of sandwich beams with a functionally graded (FG) core. After validating the finite element model using available analytical data, the effects of projectile initial velocity and kinetic energy, as well as the beam's dimensions on the impact behavior and indentation and displacement history were studied. It was concluded from these observations that for sandwich beams having functionally graded cores, the maximum contact force increases and the maximum strain decreases compared to those of sandwich beams with a homogenous core.

Experimental investigation of penetration performance of shaped charge into concrete targets

In order to develop a tandem warhead that can effectively destroy concrete targets, this paper explores the penetration performance of shaped charges with different cone angles and liner materials into concrete targets by means of experiments. The penetration process and the destruction mechanism of concrete targets by shaped charges and kinetic energy projectiles are analyzed and compared. Experimental results suggest that both kinetic energetic projectile and shaped charge are capable of destroying concrete targets, but the magnitudes of damage are different. Compared with a kinetic energy projectile, a shaped charge has more significant effect of penetration into the target, and causes very large spalling area. Hence, a shaped charge is quite suitable for first-stage charge of tandem warhead. It is also found that, with the increase of shaped charge liner cone angle, the depth of penetration decreases gradually while the hole diameter becomes larger. Penetration depth with copper liner is larger than of aluminum liner but hole diameter is relatively smaller, and the shaped charge with steel liner is between the above two cases. The shaped charge with a cone angle of 100° can form a jet projectile charge (JPC). With JPC, a hole with optimum depth and diameter on concrete targets can be formed, which guarantees that the second-stage warhead smoothly penetrates into the hole and explodes at the optimum depth to achieve the desired level of destruction in concrete targets.

Programmed input of energy into the discharge chamber of a light-gas electric-discharge accelerator of bodies

The effect is investigated of the duration of electrical energy input into working gas and of discharge power profile on the launching velocity and efficiency of acceleration of bodies using a light-gas electric-discharge accelerator with a caliber of 30 mm. It is found that, for the same energy input to the arc or for the same pulsed pressure of working gas in the discharge chamber of the accelerator, the projectile velocity in the mode being programmed is 7–10% higher, and the efficiency of conversion of internal energy of working gas to kinetic energy of projectile is 2 or 3% higher, than those in the synchronous mode.