Projectile Movement Research Articles

ВИКОРИСТАННЯ РАДАРНОЇ СИСТЕМИ MFTR-2100/40 ДЛЯ ВИЗНАЧЕННЯ БАЛІСТИЧНИХ ХАРАКТЕРИСТИК АРТИЛЕРІЙСЬКИХ СНАРЯДІВ ТА СКЛАДАННЯ ТАБЛИЦЬ СТРІЛЬБИ

У статті проведено аналіз методик визначення балістичних характеристик снарядів для складання таблиць стрільби та вивчення можливостей використання радарної системи MFTR‑2100/40 під час випробування артилерійського та стрілецького озброєння різного функціонального призначення.

Analysis and Simulation of Extracting Radar Modulation Signal Based on CIC Filter

Aimed at the difficulty of extracting weak information such as projectile movement and precession during flight., this paper analyzes the characteristics of extracting the periodic motion information of the projectile from the original data, and designs the resampling and filtering methods based on the characteristics and measured data of a certain type of continuous wave radar system. This method achieves the purpose of non-destructive extraction of low frequency weak signals.

Стенд для испытаний на стойкость к перегрузкам

A laboratory bench based on a 38 mm light gas gun (working gas — helium) is used for overload endurance test of electronic devices. The stand provides the formation of overload pulse in a wide range of amplitudes and half widths when a projectile container with the objects under study decelerates at the cracher of a special design. A radio interferometer with a wavelength of 3.2 mm is used for determination of the projectile movement as a function of time. The calculation of displacement is carried out according to the registered interferogram, the speed and acceleration dependences on time are determined by differentiation. The results of overload endurance test of power supplies and electronic assemblies with maximum amplitude of 45,000g and 70,000g with a pulse half width of 0.8 ms and 0.7 ms, respectively, are presented

Definition of approximating functions of air resistance to the projectile movement, non-linear relatively to evaluated parameters

The article considers the approach to definition of approximating functions of air resistance to the projectile movement, non-linear relatively to evaluated parameters, built on accurate (straight) methods of linear equations solution, which allows to use the method of the smallest squares to define the parameters of approximating function.

The influence of 1.5 and 3 T magnetic resonance unit magnetic fields on the movement of steel-jacketed projectiles in ordnance gelatin.

Ferromagnetic bullets can move in air or gelatin in magnetic resonance (MR) units. According to our experience, ferromagnetic bullets do not always present consistent movement. We examined factors affecting ferromagnetic projectile movement in a 1.5T and a 3T MR unit, focusing in this study on the steel-jacketed Swiss ordnance ammunition 7.5 mm GP11 Suisse. Five 7.5 mm GP11 Suisse bullets were embedded horizontally and vertically in 10 % ordnance gelatin phantoms. Before and after exposing the bullets to 1.5T (Siemens) and 3T (Philips) MR units each bullet's position was documented by a CT scan. In a second phase, the magnetic polarization of the bullets in relation to the MR units was measured by a dry magnetic portable compass (Suunto). Our results showed that the displacement of the bullets increased when subjected to a stronger magnetic field (max. Movement 1.5T: 24.4 mm vs. 3T: 101.5 mm) and that the position, i.e. orientation of the bullet toward the gantry, strongly influenced its mobility (horizontally embedded projectiles showed poor movement, vertically placed ones strong movement). One of the bullets presented a 180° rotation in the 3T MR unit. Magnetization and changing of the polarization of these ferromagnetic bullets is possible when subjected to MR units. In conclusion, the location of a bullet, and its orientation toward the gantry must be taken into account when assessing the risk of performing an MR examination on a gunshot victim in clinical and in forensic cases.

On the penetration of a rotating impactor into an elastic-plastic medium

ABSTRACTThis research is devoted to the modeling of high-speed rectilinear penetration of a rigid axisymmetric body (impactor with a flat bluntness) into an elastic–plastic media with account for its rotation about the axis of symmetry. The body has an arbitrary shape of the meridian. The resistance to the motion is represented as the sum of the body drag and the contribution of friction. The dynamic system governing the body motion is derived and the qualitative and numerical analysis of the projectile movement and perforation of a slab are performed. The problem of shape optimization of impactor with a flat bluntness is studied using evolutionary algorithm.

A moot point! A homicide case report on ambiguous projectile movement on postmortem MR

Abstract In a case of homicide with a lodged ricochet projectile in the skull, potential projectile movement was investigated by postmortem magnetic resonance imaging (PMMR). The purpose of this case report is to evaluate the different PMMR-related properties of projectiles in gunshot wounds. The deceased underwent whole-body postmortem computed tomography (PMCT) in a supine position, 3D-suface scanning with reposition of the corpse into a prone position and subsequent PMMR in the same position. For validation purposes, a control PMCT-scan in supine position followed by autopsy was also performed. The ferromagnetic properties of the projectile were tested. Imaging revealed projectile movement between PMCT and PMMR. The bullet did not produce excessive susceptibility artifacts on PMMR. Autopsy revealed no heating effects of the adjacent tissue, indicating no thermal effects by the PMMR scan. The bullet showed no ferromagnetic properties. Ballistic analysis showed only copper and lead compounds in the 9mm projectile. Therefore, the bullet migration was caused by repositioning of the corpse from a supine to a prone position along the ricochet wound channel, not by magnetic torque during the PMMR scan. PMMR allows for better anatomical detail of the bullet path within soft tissue and may be performed in cases involving the vast majority of projectiles. Knowledge about potential ferromagnetic properties may have clinical implications for imaging in surviving patients of shootings. This case report shows that bullet migration may occur independently of magnetic torque and that the localization of the bullet during postmortem imaging and autopsy may have been altered in a ricochet shot.

Punctal function in lacrimal drainage: the ‘pipette sign’ and functional ectropion

BackgroundThe aim was to assess the movements of the inferior punctum during blinking and discuss pertinent clinical applications.MethodsThis is a prospective, non‐comparative observational case‐series examining the function of inferior punctum during blinking using video recordings of the blinking action at the slitlamp with slow‐motion analysis and comparison.ResultsIn all 56 eyes of 28 patents, supero‐medial movement of the lower punctum toward the medial canthus, together with a medially directed protrusion of the inferior punctum was noted. It was also noted that the punctum blanched during this projectile movement compared to the rest of the lid margin.Simultaneous posterior rotation of the punctum was also observed in 48 eyes (85.7 per cent; 23 right eyes and 25 left eyes), resulting in apposition of the punctum to the lacus lacrimalis.In eight eyes (14.3 per cent; five right eyes and three left) from six patients, co‐existence of medial punctal ectropion led to failure of internal rotation of the punctum during blinking, even though punctal ‘pipette formation’ was preserved. These six patients all suffered from epiphora in the affected eyes. The presence of ‘pipette’ formation was calculated to have a sensitivity of 80 per cent and specificity of 100 per cent for punctal ectropion in our series. A two‐tailed Fisher exact test showed that based on our 56 eyes, these results were statistically significant (p < 0.0001).ConclusionsThe inferior punctum plays an active and important role in the drainage of tears by the mechanism of supero‐medial movement and medially directed protrusion (‘pipetting action’), failure of which contributes to epiphora. This is a highly specific sign and should be sought in the evaluation of epiphora, even in the absence of frank ectropion. In punctual stenosis where location of the punctal orifice is proving difficult, inducing the pipette sign will help in its identification.

Badania właściwości czujników akustycznych w czasie pomiarów zaburzeń ośrodka wywołanych przelotem pocisku w polu swobodnym

Badania właściwości czujników akustycznych w czasie pomiarów zaburzeń ośrodka wywołanych przelotem pocisku w polu swobodnym

Three-dimensional launch simulation and active cooling analysis of a single-shot electromagnetic railgun

An electromagnetic railgun is one of the applications of electromagnetic launchers, which are devices used to accelerate projectiles to velocities exceeding those attained with conventional propelling systems. A magnetic field is generated when current flows through two conductive rails connected by a moving armature. The current that passes through the rails exerts an electromagnetic force on the armature and causes it to accelerate to high speeds. In this work, a three-dimensional transient model for the thermal and electromagnetic solutions of the launch process is presented. The model accounts for the determination of the current and temperature profiles inside the rails, the projectile movement, and the cooling process after the first launch. Focus is given to the thermal management where five different arrangements, one without cooling and four that include cooling channels, are studied. A 10 to 50 K reduction in the peak temperature was obtained with the inclusion of cooling channels when compared to the no-cooling-channel case. It was also shown that the position and size of these channels can be optimized in order to reduce this peak temperature.

2.12. A moot point! A case report on potential projectile movement on postmortem MR

Objective This homicide case we investigate potential projectile movement on postmortem MR (PMMR) in a lodged ricochet projectile in the skull. The purpose of this case report is to evaluate the different aspects of PMMR-related properties of projectiles in gunshot wounds. Material and method The case underwent whole body postmortem computed tomography (Somatom Definition Flash Dual Source, Siemens Medical Solutions, Forchheim, Germany) in supine position, 3D-suface scanning (Atos Compact Scan 5 m, GOM mbH, Braunschweig, Germany) with reposition of the corpse to prone position and PMMR (Achieva 3.0 TX MR scanner, Philips Medical System, Best, The Netherlands). For validation purposes a later head CT-scan in supine position and subsequent autopsy was performed. Ferromagnetic properties of the projectile were tested. Results Imaging revealed projectile movement between PMCT and PMMR. The ricochet projectile showed bullet migration along the wound channel on PMMR from midbrain position to a frontal location of the bullet. The bullet did not produce susceptibility artifacts on PMMR. Autopsy revealed no heating effects of the adjacent tissue indicating no thermal effects by the PMMR scanning. The bullet showed no ferromagnetic properties after being tested by a magnet and literature review of the metallic compounding of this specific projectile. Therefore, the bullet migration was caused by repositioning of the corpse from supine to prone position along the ricochet wound channel. Conclusion Presence of susceptibility artifacts on PMMR images depend on the material compounds of the projectile. PMMR allows for better anatomical detail of bullet path within the soft tissue and may be performed in the vast majority of projectiles.

Numerical analysis of interior ballistics through eulerian-lagrangian approach

A numerical code for interior ballistics using the Eulerian-Lagrangian approach was developed to analyze polydisperse systems. The internal flows in a gun barrel and the compressibility effects were calculated using the semi-implicit method for pressure-linked equations algorithm. Ghost cell extrapolation was used for the moving boundary with projectile movement. The numerical scheme and moving boundary method were verified through the free piston motion problem. The developed code, including the combustion of the propellant, was compared with simulations of 40 mm gun firings. The results of numerical analysis agree with the simulation results, confirming the reliability of the developed code. Comparative studies were conducted with the results of the interior Ballistics of high-velocity guns code (version 2) according to porosity and propellant size. The numerical analysis of the combustion and movement of individual propellants provides deeper insight into the mechanism of gun firing and the significant factors that influence muzzle velocity.

A Flexible Online Apparatus for Projectile Launch Experiments

In order to provide a more flexible learning environment in physics, the developed projectile launch apparatus enables students to determine the acceleration of gravity and the dependence of a set of parameters in the projectile movement. This apparatus is remotely operated and accessed via web, by first scheduling an access time slot. This machine has a number of configuration parameters that support different learning scenarios with different complexities.

Application of Virtual Substance in Launch Dynamics Simulation for Self-Propelled Guns

To establish more accurate and effective gun dynamics model, which considered fully the coupling influence of projectile and flexible barrel, by introducing the virtual substance into the barrel system, a modeling method for self-propelled guns was presented. Taking a tracked self-propelled gun for an example, combining Ansys and Recurdyn, a multi-body dynamics model was built up. The correlation curves between the experimental data and the simulation result under the same firing conditions were obtained. The results show that the model can describe accurately the dynamic response and the projectile movement, which can provide theoretical references for the further research on gun launch dynamics characteristics.

Stress Analysis of Rail for an Electromagnetic Launcher due to Projectile Movement

The principle of electromagnetic launch is introduced. The equation of electromagnetic load applied on rails is given. Based on the calculated result of electromagnetic pressure, the equation for calculating bending stress of rail on the elastic foundation is deduced using superposition principle. The stress distribution in rail with the armature in different positions is analyzed. Compared with results considering the force on the rail as uniformed load, the calculating results of stress distribution are more accuracy and useful for intensity and rigidity design of electromagnetic launch. The study may provide a theoretical basis for further analysis of systemic mechanical properties.

The Use of Electronic Components in Railgun Projectiles

This paper deals with experiments and calculations performed in order to investigate the influence of the electromagnetic hardening of payloads in a railgun. This is a complex task: besides the large amplitudes of the in-bore magnetic fields due to the pulsed current, the exit of the projectile from the muzzle and the consequences of plasma arcs have to be considered. At the muzzle the magnetic induction can drop from several Teslas to zero within some microseconds, leading to very high induced voltages and electric fields in the metallic parts of the projectile. On the other hand, the electric contact established by solid armatures tends to develop into electric arcs at high velocities during the launch. These plasma arcs as well as the closing switch transients of the railgun circuit are a source of electromagnetic radiation in a broad spectral range. Some electronic devices were selected and tested with static setups corresponding to the previous conditions. In a first phase a series of static railgun experiments (no projectile movement) was performed. In a second phase, static experiments simulating the muzzle exit conditions were carried out. Finally, the influence of electromagnetic waves emitted during railgun experiments on electronic devices was investigated, using a static setup with a conventional spark gap.

Mutual Action Between MMCS Structure and Projectile After Ballistic Impact

The interaction between a projectile and metal—matrix composites (MMCs) was investigated in terms of macro cracking, petalling and particularly grain deformation of a matrix alloy at the hole section caused by the projectile at high velocity impact. Metal matrix composites were manufactured by squeeze casting using Al alloys reinforced with Al 2O3 or SiC. Additionally, laminated composites with SiC particles and back side supported by Kevlar 49® were manufactured and their ballistic behavior tested. The composite and unreinforced Al alloy targets were subjected to ballistic impact with an armor piercing projectile of 7.62mm caliber at a speed in the range of 770—800 m/s. The macro examination focused on cracking and petalling after impact. The investigation of grain deformations of matrix alloy was conducted by light microscopy in the hole section created by the projectile. The hole section created by the projectile had different profiles. Around the hole sections, different grain deformation rates in different directions took place for reinforced and unreinforced Al alloys. Strong friction took place between the projectile and hole surface and the velocity of the projectile was decreased suddenly in the hole as it met the reinforcement particles in the composite body. These led to deformations of the projectile surface and grain surrounding the reinforcement. In the case of laminate composites, the laminates were fractured and deformed in the direction of projectile movement.

2차원 압축공기-물의 압축성 이상 유동 수치 해석

Two-phase compressible flow fields of air-water are investigated numerically in the fixed Eulerian grid framework. The phase interface is captured via volume fractions of each phase. A way to model two phase compressible flows as a single phase one is found based on an equivalent equation of states of Tait's type for a multiphase cell. The equivalent single phase field is discretized using the Roe‘s approximate Riemann solver. Two approaches are tried to suppress the pressure oscillation phenomena at the phase interface, a passive advection of volume fraction and a direct pressure relaxation with the compressible form of volume fraction equation. The direct pressure equalizing method suppresses pressure oscillation successfully and generates sharp discontinuities, transmitting and reflecting acoustic waves naturally at the phase interface. In discretizing the compressible form of volume fraction equation, phase interfaces are geometrically reconstructed to minimize the numerical diffusion of volume fraction and relevant variables. The motion of a projectile in a water-filled tube which is fired by the release of highly pressurized air is simulated presuming the flow field as a two dimensional one, and several design factors affecting the projectile movement are investigated.

Dynamic response of electromagnetic railgun due to projectile movement

A model is developed to investigate the dynamic response of an electromagnetic railgun, induced by a moving magnetic pressure during launch of projectiles. As the projectile velocity approaches a critical value, resonance can occur and cause high amplitude stress and strain in the rail at the instant and location of the projectile's passage. In this study, governing equations of a railgun under dynamic loading conditions are derived that illustrate a lower-bound critical velocity in terms of material properties, geometry, and barrel cross section; this represents the worst case or a lower bound solution for the structure under a dynamic loading condition. A study is then performed to show the effect of these parameters on the critical velocity of the barrel. Accordingly, the model that accounts for projectile velocity and gun construction can be used to guide and improve barrel design.

The secondary discharges and their influence on the work of rail accelerator

The known discrepancy of the computed and actual speeds for the accelerated bodies in rail accelerators has not been explained in detail until now. One of the reasons for this discrepancy can be the occurrence of the secondary plasma crosspieces as a result of the electrical breakdown of an interelectrode distance. In this paper the breakdown mechanism, similar to the shunting of an electrical arc in plasmatrons is offered. In order to calculate the process of the primary (armature) and the secondary crosspieces interaction, a physical scheme for determining the location of the secondary crosspiece in a barrel was proposed and grounded. The formula for calculation of Lorentz forces, acting on the crosspieces is obtained. An example calculation showing the influence of the secondary crosspiece on the projectile movement in a barrel is given. This result compares well with the experiment.