Projectile Speed Research Articles

Measurement of fragments generated by hypervelocity impacts of micron-sized iron particles at grazing incidents

• Fragments of hypervelocity dust impacts are measured using a Delay Line Detector. • Majority of fragments created at grazing incidences are composed of dust projectile. • Fragmentation of projectiles increase with impact speed for grazing incidences. • The fragment speeds are distributed around 80% of the projectile impact speed. In this study, we present results from hypervelocity impacts of iron particles onto smooth surfaces under shallow incidence. For the first time, the submicron fragments of the projectiles were measured using a delay-line detector combined with a multichannel plate. Micron-sized spherical iron particles with speeds between 4–40 km/s are fired by a dust accelerator facility and impact on an optical mirror target at grazing angles of 2 ° , 4 ° , and 6 ° from the horizontal. Individual fragments generated in each impact event have been measured and analyzed including their speeds, masses, and trajectories. The total mass and momentum of fragments are comparable to their parent projectile. It is observed that most fragments have speeds exceeding 80 % of pre-impact velocities. Fragments generated at incident angle of 2 ° leave the target surface with even lower elevation angles of around 1 ° . The majority of impact fragments generated under incident angles of 4 ° and 6 ° form a spatial distribution centered an axis of 5 ° elevation, which increases with increasing impact speed. Furthermore, azimuthal scattering occurs with a distribution concentrated within ± 10 ° .

Low velocity impact study of a sandwich beams using Ritz method and finite element modelling

PurposeThe purpose of this paper is to present an applied method to design the low-speed contact between a mass and surface of a beam using an analytical solution based on the first-order shear deformation beam theory. Also, a simulation of impact process is carried out by ABAQUS finite element (FE) code.Design/methodology/approachIn theoretical formulation, first strains and stresses are obtained, then kinetic and potential energies are written, and using a combination of Ritz and Lagrange methods, a set of system of motion equations in the form of mass, stiffness and force matrices is obtained. Finally, the motion equations are solved using Runge–Kutta fourth order method.FindingsThe von Mises stress contours at the impact point and contact force from the ABAQUS simulation are illustrated and it is revealed that the theoretical solution is in good agreement with the FE code. The effect of changes in projectile speed, projectile diameter and projectile mass on the results is carefully examined with particular attention to evaluate histories of the impact force and beam recess. One of the important results is that changes in projectile speed have a greater effect on the results than changes in projectile diameter, and also changes in projectile mass have the least effect.Originality/valueThis paper presents a combination of methods of energy, Ritz and Lagrange and also FE code to simulate the problem of sandwich beams under low velocity impact.

Analysis of the structure and properties of triangular composite light-screen targets

Abstract With the development of light-screen targets for ballistic projectiles, not only must accuracy in the measurement of projectiles be assured but also the installation of the system and error compensation in the initial calibrations must be considered. We have designed a triangular composition light-screen target that is easy to install, derived expressions for the speed and direction of ballistic trajectories based on intersecting-CCD vertical targets, and conducted analyses of the points of impact and projectile speed. Results show that errors in the point of impact are affected by the coordinates of the target plane. Positional errors gradually increase with the distance from the origin. The horizontal angle error with the trajectory line does not exceed 0.3°, whereas the vertical angle error does not exceed 0.2°. Errors in the speed of the projectile remain relatively stable when the vertical coordinates are greater. Errors in speed and direction, as well as error fluctuations, are smaller on the x = 0 plane, making it the ideal region for error compensation in initial calibrations.

Experimental and Numerical Investigation of the Impact of a Blunt Projectile with a Perforated Plate

This paper experimentally and numerically investigated the impact of a blunt projectile to perforated steel targets. In this study, projectiles were made of AISI 52100 and perforated plates were made of AISI 1045. In order to investigate the effect of the hole diameter on the projectile, three different diameters of the hole were considered, along with the effect of the projectile overlap with the hole. After examining different hitting states, the projectile was deviated from its movement direction after hitting the hole and changed from vertical hit to skew. The deviation of the projectile increased when the diameter of the hole increased or the amount of projectile overlap with the hole increased. Then, numerical modeling of impacting the projectile was performed by ABAQUS software and the results were compared with experimental results and the accuracy of the model was confirmed. And this model was used to investigate the effect of initial projectile speed on deviation of the projectile, accordingly, an increase in the initial velocity of the impact led to an increase in the deviation of the projectile.

Numerical study of the anti-penetration performance of sandwich composite armor containing ceramic honeycomb structures filled with aluminum alloy

The aim of this work was to study the anti-penetration effect of sandwich composite armor with ceramic honeycomb structures filled with aluminum alloy under the impact of high-speed projectiles. The finite element software ABAQUS was used to conduct numerical simulation research on the process of a standard 12.7-mm projectile penetrating sandwich composite armor. The armor-piercing projectile model was simplified as a rigid body. The numerical simulation models were applied to three different sandwich composite armor structures (A, B, and C), each with a total armor thickness of 25 mm. The penetration resistance of the three kinds of composite armor was studied. We obtained velocity curves for the rigid projectile penetrating the different structures. The failure forms and penetration resistance characteristics of the three composite armor structures adopted in this paper were analyzed. In addition, the velocity reduction ratio is proposed as an index to evaluate the penetration resistance performance of the armor. The simulation results revealed decreasing rates of projectile speed in the structures A, B, and C of 69.6%, 91.1%, and 100%, respectively. The third composite armor (structure C) designed here has excellent penetration resistance and can block the penetration of a high-speed (818m/s) rigid projectile. This study can provide some reference for the application of laminated armor material in anti-penetration protection structures.

Electromagnetic Launching System as an Alternative to Non-Destructive Sonic Wave Generation for Steel Bar Length Determination

Soil nailing system is widely used along highways in Brazil. Non-destructive techniques have been used to estimate the length of installed soil nails. Sonic Echo and Impulse Response techniques evaluate the bar length using sonic wave propagation. The methods are similar and consists in generate an impact with a hammer. Results may be affected by this non-standard procedure. This paper aims to propose an automated sound wave generation in order to carried out tests quickly, with reproducibility and without operator dependence. An electromagnetic launching system was developed, which uses a projectile in place of the hammer, and the electromagnetic force instead of human force. The sound data was received by a microphone and sent to the computer by a microcontroller, making the system compact and portable. Projectile output speed optimization and impact reproducibility were analyzed. Nails length were obtained by both time and frequency domain data analysis. Results showed high reproducibility under the same initial condition. Propagation velocity presented a relative error less than 1% for steel bar with length of 1 m.

Numerical simulation research on steel/ceramic composite target plate structure against penetration of high-speed projectile

This study is mainly based on LS-DYNA to simulate the entire process of high-speed projectile penetration into the steel-ceramic composite target structure. In the process of projectile penetration into the target, the impact speed of projectile, the structure of steel-ceramic composite target plate and other key factors on the target failure and target transient response and the law are explored. The article tried different thickness combinations of the steel plate ceramic structure, obtained the best thickness combination according to the after-effect of penetration, and analyzed the remaining velocity and remaining rod length of the projectile. The results show that the composite target plate has the best protection performance under the condition of the thickness ratio of panel-sandwich-back plate of 1:2:1, and the composite target plate has better anti-penetration performance against projectiles with a speed greater than 1500 m/s.

Martian Ice Revealed by Modeling of Simple Terraced Crater Formation

AbstractArcadia Planitia, a region in the northern midlatitudes of Mars, displays an uncommonly high abundance of simple craters with a concentric morphology, which is indicative of layering beneath the surface. Radar measurements suggest that the near surface layers could be made of excess water ice. In this study, we select two of these impact structures of similar size (Dc ~ 500 m), model their formation through iSALE shock physics code, and investigate the dependence of the final crater morphology on the material model parameters (cohesion and friction coefficient). Our parameter study shows that the intact and damaged cohesions of the nonporous ice play a fundamental role to obtain a good fit between our models and the topographic profiles taken from the digital terrain models in terms of crater diameter, crater wall inclination, and depth and size of the upper terrace. The central pit shape is instead controlled by the damaged friction coefficient of the basaltic crust, but it is mainly affected by projectile density and speed. Our results confirm that two layers of relatively pure water ice, each with different rheology and porosity, can explain the unique double‐terraced morphology of impact craters in Arcadia Planitia. The low values of cohesion we find for the ice might point to snowfall as emplacement mechanism in the region. The different thicknesses of the ice layers in the two crater areas seem to suggest variations in ice deposition and/or evolution history across Arcadia Planitia.

Friction in a strongly magnetized neutral plasma

A charged projectile generates an electrostatic wake as it moves through a background plasma. This wake normally gives rise to a drag force that acts antiparallel to the velocity vector of the projectile, and is commonly referred to as the stopping power. A recent theory (Lafleur T and Baalrud S D 2019 Plasma Phys. Control. Fusion 61 125 004) predicted that an additional component of the friction force that is perpendicular to both the projectile velocity and the Lorentz force arises when a plasma is strongly magnetized. We extend the previous analysis of this transverse friction force, which was based on the one-component plasma model, to treat a two-component charge-neutral electron-ion plasma. The direction and magnitude of the transverse force is found to depend on the projectile speed relative to the electron and ion thermal velocities, and to change sign three times. For projectile speeds below a certain threshold, the transverse force is dominated by collisions with ions, while above this threshold, only electron collisions contribute. The average trajectory of the projectile is significantly altered by the transverse force as it slows.

Finite Element Analysis for Impact Tests on Polycarbonate Safety Guards: Comparison With Experimental Data and Statistical Dispersion of Ballistic Limit

Abstract Design and testing of machine guards are provided by international standards in which the inadequacy/suitability of the tested materials for machine guards is obtained by the perforation/nonperforation of the guard in an experimental test at the maximum foreseeable speed of a standardized projectile. Uncertainties and limitations of this standardized test are known by researchers, but a better testing procedure is not already agreed on the standardization level. In this paper, finite element analysis of the impact of three different projectiles of a given mass on polycarbonate guards is presented and compared with experimental tests made using a standardized gas cannon. The good correlation found in terms of ballistic limit, energy absorbed, and residual velocity is presented trying to open the discussion to a “probability of perforation.” Moreover, a statistical analysis of experimental results, based on a nonlinear regression model, is briefly introduced. The penetration behavior is described by the well-known Recht and Ipson equation, and an evaluation of the statistical dispersion of the ballistic limit for each type of projectile is presented through the calculation of confidence intervals.

Effect of the magnus force and torque on the projectile flight range

The paper considers the origin of the Magnus force and torque in the course of the projectile flight; analytical dependencies for their determination are given and justified. The mutual orientation of the Magnus force and angular torque vectors with respect to those of the drag and lift forces, as well as with respect to the stalling, polar quenching and equatorial damping torques acting on the projectile in flight is discussed. The effect of the Magnus force and torque on the firing characteristics of artillery systems is assessed. A mathematical model of the projectile flight is presented, as well as constraints that are imposed on it and that do not considerably affect the accuracy of the description of the spatial motion of the projectile. The mathematical model is implemented programmatically on the basis of a standard subroutine for numerical integration of differential equations written in the Maple software and contains the motion equations for the projectile mass center, the motion equations with respect to the projectile mass center and equations that allow one to determine the coordinates of the projectile fall points in the base reference system. To assess the effect of Magnus force and torque on the projectile flight range, the difference method is employed, which consists in solving the system of differential equations of the spatial motion of the projectile such that changing the magnitude of the Magnus force and torque (at the assumption of the constancy of the aerodynamic forces and torques), one obtains the variation in the projectile flight range. A protocol and a scheme for assessing the effect of deviation of the projectile range on the accuracy of determination of the Magnus force strength and torque, as well as the results of numerical simulation of the deviation of the flight range for the ОФ-462Ж projectile of the 122-mm howitzer Д-30 depending on the accuracy of determination of aerodynamic force coefficients and Magnus torque are presented. It is shown that the largest deviations in the projectile flight range are observed when shooting at large launching angles and full charge (projectile speed 690 m / s); the smallest corresponding values are observed for the fourth charge (projectile speed 276 m / s) at small launching angles.

Experiment study on the influencing factors of mechanical response of HMX-based PBXs in the high-g deceleration environments

ABSTRACT An impact test method was designed to study the mechanical behaviors of explosive charges in deceleration environments. With this method, the deformation and density variation of explosive charges in various deceleration environments can be obtained by changing the decelerations. The deceleration can be precisely changed without changing the strength of target and the speed of projectile. The high-g deceleration environment was simulated by this method. Then, the factors which influence the mechanical response of cyclotetramethylenete-tranitramine (HMX)-based polymer-bonded explosives (PBXs) in the high-g deceleration environments were investigated. The variation of density, macro size, and meso-damage was obtained. The results showed that the initial density, binder type, and particle size have different effects on the deceleration resistance of HMX-based PBXs, then the mechanism was discussed. The shock sensitivities of the PBXs with different densities, binders, and particle sizes were tested. The relationship between the shock wave safety and the deceleration resistance was discussed.

Design of a 40mm Caliber Ballistic Correction Steering Gear System

The ballistic correction projectile uses several limited open-loop corrections to reduce the error of the projectile flight or the deviation of the projectile from the target due to the target movement, thereby reducing the projectile dispersion error and improving the hit rate. This paper draws on the existing advanced steering gear design, and improves the rudder blade airfoil and its plane shape according to the flight speed of the ballistic correction projectile (Mach 2). Through the analysis of degrees of freedom, a pair of limit devices have been added to the housing to make the servo system work more stable and efficient. At the end of the paper, the conclusion that the 5V voltage is better than the 3.3V power supply is obtained through the control experiment. The safety and reliability of the servo system are further verified by the anti-torque simulation of the cam mechanism and the anti-overload simulation of the servo motor.

ЭКСПЕРИМЕНТАЛЬНОЕ ИССЛЕДОВАНИЕ ПРОНИКАНИЯ ЦИЛИНДРИЧЕСКИХ УДАРНИКОВ В СУХОЙ ПЕСОК

For the most complete study of the laws of shock interaction of solids with soil barriers, further development of experimental techniques for recording the parameters of the interaction process in direct and inverse experiments is necessary. In this work, to determine the parameters of the movement of the projectile (displacement and speed) in a direct experiment, a millimeter-wave radio interferometer is used. This method allows continuous recording of the movement of the rear end of the striker with high accuracy over a wide range of movements. Using the proposed technique, experiments were carried out to record the motion parameters of cylindrical impactors made of steel and aluminum alloy when interacting with an obstacle made of dry sand. At the same time, the movement of the rear end of the striker was also controlled using high-speed filming until the full immersion of the striker. The experiments showed that the measurement results obtained using two methods coincide within the measurement error. Based on the experiments, it can be concluded that the methodology for determining the displacement and velocity of a projectile in a ballistic experiment using a millimeter-wave radio interferometer allows continuous measurement of large displacements (100 mm or more), including when completely immersed in a target with sufficient practical goals accuracy. Based on the results of the experiments, the dependences of the movement of the projectile and its speed on time are constructed. A change in the penetration law was found with a decrease in the penetration velocity to values less than 100 m/s.

Study on Correlation Characteristics of Static and Dynamic Explosion Temperature Fields

The warheads such as missiles and artillery shells have a certain speed of motion during the explosion. Therefore, it is more practical to study the explosion damage of ammunition under motion. The different speeds of the projectiles have a certain influence on the temperature field generated by the explosion. In this paper, AUTODYN is used to simulate the process of projectile dynamic explosion. In the experiment, the TNT spherical bare charges with the TNT equivalent of 9.53kg and the projectile attack speed of 0,421,675,1020m/s were simulated in the infinite air domain. The temperature field temperature peaks and temperature decay laws at different charge rates and the multi-function regression fitting method were used to quantitatively study the functional relationship between the temperature and peak temperature correlation calculations of static and dynamic explosion temperature fields. The results show that the temperature distribution of the dynamic explosion temperature field is affected by the velocity of the charge, and the temperature distribution of the temperature field is different with the change of the charge velocity. Through the analysis and fitting of the simulation data, the temperature calculation formula of the static and dynamic explosion temperature field is obtained, which can better establish the relationship between the temperature peak of the static and dynamic explosion temperature field and various influencing factors, and use this function. Relational calculations can yield better results and meet the accuracy requirements of actual tests.

Experimental study of the honeycomb composite material under high velocity impact

This study deals with the effect of complex material made from (Kevlar29, Honeycomb Aluminium and Carbon fibers) under high velocity is measured, also this material tested to specify the mechanical properties, then the high-impact loading utilizing the energy absorption tests were performed experimentally by using a gas gun device with shape of impactors flat cylindrical bullets. The discussion of the results of this work was termed under the failure of the coupling mode of the projectiles. The velocity level and defamatory affect the kinetic energy of the projectile. The thickness of the target has an impact on the projectile speed. The findings are discussed in terms of the work done to link the failure modes with the kinetic energy fall of the projectile and its effect on ballistic maximum velocity. The effect on the rate of the target thickness was then addressed. The vitality assimilation was anticipated by expecting that all out work done in the disfigurement of the plates is comparable to the total loss of the motor vitality of the shot. The connection between possible speed and the thickness of composite material was perceived. The hypothetical outcomes demonstrated great understanding contrasted and the test work.

Experimental study of the honeycomb composite material under high velocity impact

This study deals with the effect of complex material made from (Kevlar29, Honeycomb Aluminium and Carbon fibers) under high velocity is measured, also this material tested to specify the mechanical properties, then the high-impact loading utilizing the energy absorption tests were performed experimentally by using a gas gun device with shape of impactors flat cylindrical bullets. The discussion of the results of this work was termed under the failure of the coupling mode of the projectiles. The velocity level and defamatory affect the kinetic energy of the projectile. The thickness of the target has an impact on the projectile speed. The findings are discussed in terms of the work done to link the failure modes with the kinetic energy fall of the projectile and its effect on ballistic maximum velocity. The effect on the rate of the target thickness was then addressed. The vitality assimilation was anticipated by expecting that all out work done in the disfigurement of the plates is comparable to the total loss of the motor vitality of the shot. The connection between possible speed and the thickness of composite material was perceived. The hypothetical outcomes demonstrated great understanding contrasted and the test work.

Analysis of interior ballistic performance degradation of a worn gun barrel based on finite element method

A comprehensive accelerated life test of a 12.7mm caliber barrel gun barrel was carried out to study the variation in interior ballistic performance during the lifespan of a large- caliber machine gun. The wear mechanism at different positions in the bore was analyzed, and the wear data for the bore was obtained from the test. On this basis, a three-dimensional barrel- wear finite element model was established using the parametric model-ing method. The variation law of interior ballistic performance and the influence of wear location on ballistic performance were studied. The results showed that, after shooting 4300 rounds, the radial swing of the projectile head at the muzzle reached 0.35 mm and the projectile rotational speed decreased by 57.5% compared with the unworn performance. In addition, the wear on the initial position of the rifling not only caused the swing of pro-jectile in the barrel, but also aggravated the wear of other parts of the inner wall. The wear at the muzzle had a more obvious effect on the rotational speed of the projectile. Finally, it was concluded that the fundamental reason for interior ballistic performance degradation was wear on the initial position of the rifling.

Target dependence of postcollision interaction effects on fully differential ionization cross sections

We have measured and calculated fully differential cross sections (FDCS) for ionization of helium by 75-keV proton impact. Ejected electrons with a speed close to and above the projectile speed were investigated. This range of kinematics represents a largely unexplored regime. A high sensitivity of the FDCS to the details of the description of the few-body dynamics, reported earlier for ionization of ${\mathrm{H}}_{2}$, was confirmed. A peak structure was found in an electron angular range between the regions where the so-called binary and recoil peaks are usually observed. The need for nonperturbative calculations using a two-center basis set is demonstrated.

2019 Barringer Medal for Mark Cintala

2019 Barringer Medal for Mark Cintala