Kinetic Energy Of Projectile Research Articles

X-Ray Emission from Zr, Mo, In and Pb Targets Bombarded bySlow Highly Charged Arq+(q = 13,14,15,16) Ions

We study the L x-ray emission from Zr, Mo and In targets and M x-rayemission from Pb target under bombardment of low energy Arq+(q = 13,14,15,16) ions. The relative x-ray yields were measuredin the projectile kinetic energy range 210–360 keV. It is found thatthe relative x-ray yields from Zr, Mo and Pb targets increase with theincreasing projectile kinetic energy for Ar14+ and Ar16+projectiles and depend on the potential energy of the projectileremarkably.

X-ray emission in lithium-like and helium-like argon ions colliding with molybdenum surfaces

We have measured the spectra and yields for Ar K and Mo L x-rays from Ar 15+ and Ar16+ ions colliding with molybdenum (Mo) surfaces . The spec tra and yields are measured as a function of the projectile kinetic energy. In t he case of Ar15+ -Mo, both Ar K x-rays and Mo L x-rays are observe d, and the yields of Ar K x-rays are related to the projectile kinetic energ y, the potential energy of hollow atom formed in the interaction, the competitio n of the x-rays emitting from the projectile and the target etc. But in the case of Ar15+-Mo, Mo L x-rays are observed only. The yields of Mo L x- rays induced in both cases increase with the projectile kinetic energy.

Influence of weathering and gamma irradiation on the mechanical and ballistic behavior of UHMWPE composite armor

Fiber reinforced polymeric-matrix composites have been extensively applied to various structural components successfully replacing many conventional materials, especially in land, sea, air and aerospace vehicles and in sporting goods. Since World War II, polymeric materials have been used in military applications, especially as ballistic armor. Due to their great capacity for absorbing the kinetic energy of projectiles, ultrahigh molecular weight polyethylene (UHMWPE) fibers are presently used in composite armors for personnel and vehicle protection. However, polymers are liable to degrade when subjected to environmental agents such as sunlight, rain, radiation, etc. The aim of the present work was to use accelerated tests, short exposures to weather and gamma radiation, to study the influence of aging agents on the mechanical and ballistic performance of a UHMWPE composite armor. Composite panels were submitted to ballistic tests using 9 mm caliber projectiles. The mechanical and ballistic characteristics of composite were related to macromolecular modifications induced in the polymer by the environment through physicochemical testing. Exposure to environmental agents induces changes in the UHMWPE macromolecular chains, altering the mechanical properties and the ballistic behavior of the composite. The use of accelerated tests may be an adequate way to predict the effects of environmental agents on the performance of ballistic armor. These results are presented and discussed.

Nanoscopic surface modification by slow ion bombardment

We present systematic scanning tunneling microscopy (STM)/atomic-force microscopic (AFM) investigations on nanoscopic defect production at atomically clean surfaces of SiO 2, Al 2O 3 and highly oriented pyrolytic graphite (HOPG) after bombardment by slow (impact energy≤1.2 keV) singly and multiply charged ions under strict ultra-high vacuum (UHV) conditions. Combined STM and AFM studies show that on HOPG only “electronic” but no visible topographic defects are created by such ion bombardment. On the monocrystalline insulator surfaces, well-defined topographic features of typically nm extensions are produced (“potential sputtering”). For Al 2O 3 and HOPG, a clear dependence of the defect size on the projectile ion charge is demonstrated. These results are discussed in view to possible new nanoscopic surface structuring and modification methods for which the kinetic projectile energy plays a minor role only.

Energy loss studies of protons colliding with ethane: preliminary results

This paper reports theoretical calculations for projectile kinetic energy loss and stopping power of protons colliding with C 2H 6, for projectile energies of a few eV up to 25 keV. The many body character of the system and the strong coupling of the electronic and nuclear degrees of freedom make this system suitable for study using electron–nuclear dynamics. We report the stopping cross section as well as the electron capture cross section as a function of the projectile kinetic energy. We find that chemical dissociation plays an important role in charge exchange due to the bond breaking during the collision. We also obtain the stopping cross section using Bragg’s rule in order to analyze chemical effects (bond contributions). Finally, comparison to the available experimental data is provided.

Analytical modeling for the ballistic perforation of planar plain-woven fabric target by projectile

This paper presents an analytical model to calculate decrease of kinetic energy and residual velocity of projectile penetrating targets composed of multi-layered planar plain-woven fabrics. Based on the energy conservation law, the absorbed kinetic energy of projectile equals to kinetic energy and strain energy of planar fabric in impact-deformed region if deformation of projectile and heat generated by interaction between projectile and target are neglected. Then the decrease of kinetic energy and residual velocity of projectile after the projectile perforating multi-layered planar fabric targets could be calculated. Owing to fibers in fabric are under a high strain rate state when fabric targets being perforated by a high velocity projectile, the mechanical properties of the two kinds of fibers, Twaron® and Kuralon®, respectively, at strain rate from 1.0×10−2 to 1.5×103 s−1, are used to calculate the residual velocity of projectile. It is shown that the mechanical properties of fibers at high strain rate should be adopted in modeling rate-sensitivity materials. Prediction of the residual velocities and energy absorbed by the multi-layered planar fabrics show good agreement with experimental data. Compared with other models on the same subject, the perforating time in this model can be estimated from the time during which certain strain at a given strain rate is generated. This method of time estimation is feasible in pure theoretical modeling when the perforation time cannot be obtained from experiments or related empirical equations.

Experimental investigation of high velocity ice impacts on woven carbon/epoxy composite panels

Abstract Spherical-shaped ice simulating hailstones were projected onto woven carbon/epoxy composite panels to determine the damage resistance of thin-walled composite structures to ice impact, and to observe the resulting damage modes that occur over a wide range of velocity. To study the behavior of ice in isolation from the complex response of the composite panel targets, impacts onto a dynamic force measurement device were first conducted. These experiments show a linear relationship between the peak measured force and the projectile kinetic energy, regardless of projectile size. Composite panel impact experiments show a linear relationship between the kinetic energy at which failure initiates, referred to as the failure threshold energy (FTE), and the thickness of the panel. Impacts at kinetic energies greater than the FTE produced a multiplicity of damage modes. Glancing impact tests on composite panels show that the FTE can be accurately estimated using a simple trigonometric scaling relationship.

Case for projectile kinetic energy gain in stopping power studies

AbstractUnder certain collision conditions, a swift ion projectile colliding with a target will gain rather than lose kinetic energy, contrary to the standard conception of stopping power. In this work, we consider the conditions for such a collision such that the energy loss is negative, that is, that there will be projectile kinetic energy gain. In particular, for a target initially in the ground state we find that the projectile gains kinetic energy only when charge exchange and de‐excitation processes are involved. This occurs when the electron affinity of the projectile is larger than the ionization potential of the target. Consequences of this effect are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem 94: 215–221, 2003

Parametric Optimization of Electrothermal-chemical (ETC) Launchers

The research on a 30 mm electrothermal-chemical (ETC) gun including theoretical simulation and experimental results is presented in this paper. The predictions of the theoretical model which is composed of three parts (i.e., pulse forming network, plasma generator and interior ballistics) are in good agreement with the experiments. In addition, we have performed some liquid propellant and solid propellant experiments, respectively. Among the solid propellant experiments, we have investigated the ignition modes of propellant and high velocity launchers. As a result, the 25: 75 mixture of octane and hydrogen peroxide has a better effect than other liquid propellants. When the propellants are ignited nearby the bottom of projectile in chamber by using an ullage tube connected with the plasma generator, the kinetic energy of projectile will increase, while the chamber pressure will decrease. With a total input electrical energy of 180 kJ, the exit velocity of projectile is up to 2.1 km/s or so.

A new energy source for organic synthesis in Europa's surface ice

Colored regions on Jupiter's satellite Europa and other icy bodies in the outer solar system may be contaminated by organic macromolecular solid material that is produced when surface ices are exposed to electrical energy. Hypervelocity meteorite impacts and fracture may release tidal and tectonic stresses in icy crusts in the form of electrical discharges, which provide the energy for in situ synthesis of the organic solids. We report for the first time here on measurements of electrical discharge, light emission, and magnetic phenomena in hypervelocity impacts into ice with small iron projectiles having velocities ∼5 km s−1. In these experiments, part of the impacting projectile's kinetic energy is converted into electrical potential, while the mechanical disruption of the impact also causes the release of stress energy as light, heat, and electrical and magnetic fields as secondary emissions. These new energy sources described here suggest that the dark material in the area of impact craters may be solid phase, complex organic material called tholin, generated from the energy of the impacts. The morphology of Europa's impact craters is suggestive of fluidized colored material welling up from the fracture zone, probably during crater formation, but possibly later. Large pools of liquid water might persist under the meteorite crater for thousands of years [Thomson and Sagan, 1992], with the potential for prebiotic chemistry to take place at an accelerated rate due to energy pumped in from the secondary emissions.

The effect of laminate stacking sequence of CFRP filament wound tubes subjected to projectile impact

The work described herein focuses on the effect a change in the laminate stacking sequence has on the ability to dissipate kinetic projectile energy. Two different T800 carbon fibre filament wound tubes in an epoxy matrix with lay-ups of [−35°/+35°/90° 3/−35°/+35°/90° 3/−35°/+35°] (laminate A) and [90° 6/(−35°/+35°) 3] (laminate B) are investigated. The tubes are subjected to impacts up to and above the ballistic limits. The energy dissipated by material failure and friction is quantified and shown to be similar for the two laminates at the respective ballistic limits. The results indicate that laminate B provides the best energy dissipation performance as a result of a higher ballistic limit than laminate A and a difference in the strain energy due to a different local response of the two laminates.

Transient flexural waves in a disk and square plate from off-center impact

Flexural waves in a disk and square plate produced by off-center impact are analyzed. The effects on maximum transient stress σmax of boundary shape, edge constraint, thickness, side of square plate or diameter of disk, and eccentricity of center of impact are studied. While prior analytical work has been confined to disks for simplicity, ballistic experiments were performed using square plates for practical reasons. The two geometries agree better for central impact or edges that are simply supported or clamped. Analytical results show some intensification as center of impact approaches the edge, but this is insufficient to explain the measured rise in residual projectile kinetic energy after penetrating a ceramic tile. This reveals the inadequacy of the crack initiation mechanism as the primary model of defeating the projectile by ceramic tiles.

The Biomechanics of an Overarm Throwing Task: a Simulation Model Examination of Optimal Timing of Muscle Activations

A series of overarm throws, constrained to the parasagittal plane, were simulated using a muscle model actuated two-segment model representing the forearm and hand plus projectile. The parameters defining the modeled muscles and the anthropometry of the two-segment models were specific to the two young male subjects. All simulations commenced from a position of full elbow flexion and full wrist extension. The study was designed to elucidate the optimal inter-muscular coordination strategies for throwing projectiles to achieve maximum range, as well as maximum projectile kinetic energy for a variety of projectile masses. A proximal to distal (PD) sequence of muscle activations was seen in many of the simulated throws but not all. Under certain conditions moment reversal produced a longer throw and greater projectile energy, and deactivation of the muscles resulted in increased projectile energy. Therefore, simple timing of muscle activation does not fully describe the patterns of muscle recruitment which can produce optimal throws. The models of the two subjects required different timings of muscle activations, and for some of the tasks used different coordination patterns. Optimal strategies were found to vary with the mass of the projectile, the anthropometry and the muscle characteristics of the subjects modeled. The tasks examined were relatively simple, but basic rules for coordinating these tasks were not evident.

Electronic stopping in ion–fullerene collisions

The electronic friction experienced by a multiply charged ion interacting with the valence electrons of a single fullerene is an important aspect of the collision dynamics. It manifests itself in a considerable loss of projectile kinetic energy transferred to the target, resulting in excitation. The latter mainly leads to direct ionization and multifragmentation and can be recognized in specific patterns of the fragmentation spectra. These fingerprints can be used to quantify electronic stopping and to identify its typical properties as known from particle–solid interactions, such as the oscillation of the electronic stopping with the projectile atomic number Z. These essentially many-body effects can therefore be studied in a well-defined system of finite size.

Hybrid Electromagnetic System for Acceleration of Solids

The electroexplosive and electrothermal mechanisms and the principles of conduction and induction electrodynamics are used simultaneously to convert electromagnetic energy to the kinetic energy of projectiles. This approach is implemented on the basis of the well–known configuration of a coaxial pinch accelerator. It is established that there is an “active” lengths of the barrel on which the system ensures launching with nearly constant acceleration. For a barrel length of 340 mm and a barrel diameter of 17 mm, bodies with a mass of 1—12 g are accelerated to velocities of 3.4—1.45 km/sec with an energy conversion efficiency of 25—29% at a capacitive storage voltage of 1.75 kV and a discharge current of up to 150 kA. Bodies with a mass of 40—80 g (barrel diameter 25 mm are accelerated to velocities of 1.3—1.0 km/sec with an efficiency of 28—20% at a voltage of 3.5 kV and a current of up to 220 kA.

成形爆薬による超高速衝突試験と飛しょう体形状の影響評価

Seven shaped-charge hypervelocity impact tests were conducted to evaluate the Japanese Experiment Module (JEM) space debris protection stuffed Whipple shield at an approximate velocity of 11 km/s. The shape and the characteristics of the shaped-charge jet differ from those of the light gas gun because of the jet generation mechanism. It is therefore necessary to evaluate and compensate the results for a solid aluminum sphere, which is the design requirement. Comparative two-dinensional hydrocode simulations were conducted to assess the shape effects on the impact damage. The shapes assessed are arrowheads that simulate the shaped-charge jet, hollow cylinders, and solid spheres. By assessing the projectile kinetic energy, the authors concluded that the shaped-charge jet produces three to five times more severe damage to the pressure wall than the solid sphere, even if both have the same mass. The authors also confirmed that the shaped-charge testing and hydrocode simulation correlate well for the pressure wall damage.

Evaluation of Impact Properties of Thermal Barrier Coating on Gas Turbine Components.

For studying environmental deterioration and damage, the foreign object impact tests were carried out for thermal barrier coating material by use of gas-gun-type accelerator, and then FEM analysis was conducted for simulating impact damage. As a result, following conclusions were obtained. 1)Impact damage of the single-particle impact test was caused in the boundary between top coating and bond coating, and formed cracks of the delamination which brought the spalling of top coating. 2)From FEM analysis, shear strain arises in the impact point, and extends along the surface of coating. Maximum peak distribution of shear strain almost corresponds to delaminated length. 3)Delaminated length of coating which is equivalent to impact shear strain could be evaluated by standardized kinetic energy of projectile, that is kinetic energy divided by cross sectional area of projectile.

Neutralization of hyperthermal multiply charged ions at surfaces: Comparison between the extended dynamical overbarrier model and experiment

Within a semiclassical model, we investigate the dynamic neutralization and relaxation of slow ${(E}_{\mathrm{kin}}<100\phantom{\rule{0ex}{0ex}}\mathrm{eV})$ multiply charged ions which are reflected on metal surfaces. Special emphasis is devoted to near-surface interaction mechanisms. Our model includes a Monte Carlo sampling over projectile parameters and detailed ionic structure calculations of projectile energy levels. In a full trajectory simulation, our results simultaneously comply with measured trends in projectile kinetic energy gains and final charge-state distributions of the reflected ions as well as total electron yields and spectra. Recently discovered characteristic features in the electron spectra can be uniquely assigned to distinct above-surface regions of the projectile trajectory.

Charge transfer and electron emission in ion–surface interactions

The formation and decay of multiply excited projectiles during collisions of slow highly charged ions with metal and insulator surfaces have been simulated based on a classical over-barrier model. Simulations including the full trajectory of the projectile have recently allowed the simultaneous evaluation of projectile kinetic energy gains, final charge-state distributions and emitted Auger electron yields in reasonable agreement with experiments. Due to the many-electron nature of these interactions, no detailed quantum mechanical calculations are available. In contrast, for low charge states of the incident ion, quantum mechanical close-coupling calculations have been performed that provide detailed information on resonance formation, hybridization, and electron transfer, including the effects of external electric fields. In this paper, some aspects of ion–surface collisions are reviewed within both (many-electron) over-barrier models and quantum mechanical single-electron expansion methods.

Grooves Effect on Lift: Data Correlation and Prediction for Kinetic Energy Projectiles

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.