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We study the transient indirect effect of a rifle bullet on bone in the gelatin-bone composite target experimentally and computationally. The process of a 56 type 7.62-mm rifle bullet penetrating the composite target has been simulated using numerical method. The experiment provided the criteria for verifying the correctness of the numerical model. We have obtained tomographic data of bone by CT scans, and also defined the bone as different layers by the gray scale to simulate its heterogeneity. The computed results are in good agreement with the experimental data. Effects of the impact velocity and bone location on damage caused to the composite target have also been studied. The numerical results imply the follows: When the velocity of bullet increases, the stress on bone also increases with the earlier pressure peak; When the bone is located in a certain distance from the trajectory, it will not be fractured, although it is affected by the stress wave.

We describe several examples where we use cross-correlation functions to quantify the similarity of 2D surface profiles or of 3D areal surface topography images. The applications have included (1) the manufacture of standard reference material (SRM) bullets and casings, (2) methods to assess whether bullets or casings have been fired by the same firearm, and (3) research to quantify similarities or differences between profiles of the same surface measured by different techniques or between a master surface and its replicas. The cross-correlation maximum is the functional parameter used to quantify similarity. A second parameter, called the relative profile (2D) difference or relative areal topography (3D) difference, may also be used to quantify differences and to recognize the ambiguous condition when two results have different vertical ( z -) scales but identical shapes. Most of these examples have been applied in support of ballistics inspection methods in crime labs, but the methods are generally useful for estimating the accuracy of surface replication techniques or the ability of different surface topography instruments to measure the same surface and provide the same result. The instruments used in these studies were a stylus instrument and a Nipkow-disk type confocal microscope. Cross-correlation functions may also be used to assess differences resulting from the use of different filters to modify the same surface profile or topography image.

This study evaluates the energy absorption, perforation and damage evolution created by cylindrical projectile of different nose geometries in woven roving mat/epoxy laminates with 0.45� orientation. A series of ballistic impact tests have been carried out on the laminate with projectile nose geometries representing hemispherical, conical, and conical with round nose and truncated tip. A gas gun projectile launcher set-up was employed to impact the target at different speeds. The damage pattern, perforation mechanism and ballistic limit for each type of projectiles have been studied. Truncated-nose projectile shows the highest ballistic limit while sharp-nose shows the lowest. A quasi-static punch test was carried out on targets with projectiles of above-mentioned nose geometries to assess the damage evolution at a constant strain rate. The maximum load required to cause perforation during punch test was noted for hemispherical-nose projectile. An in-depth layerwise analysis was carried out to analyse the damage in each layer. Copyright � 2008 Taylor & Francis.

There has long been a need to understand the impact response of explosive materials, and continual improvements result from the design of careful, well-instrumented experiments. This article summarizes details of the design and construction of a laboratory facility capable of launching projectiles at explosive targets at velocities up to 1500 m s−1. There are two types of experiment that are required. In the first, a gun launches a plate of great planarity at an equally flat target. This geometry is known as plate impact and a target loaded in this manner experiences a state of one-dimensional strain. This loading is accomplished by launching plane impactors onto targets aligned to micron tolerances, normal to the impact axis to less than 0.5 mrad of tilt. In the second, it is required to attain the ability to recover impacted explosive targets that have been loaded in one-dimensional strain for subsequent microstructural assessment. The development of this capability will be described in a subsequent pub...

An improved procedure for modeling the operation of a light-gas gun is proposed. The motion of working bodies in both the firing chamber and the light-gas chamber is studied within the framework of the mechanics of heterogeneous media. The problem of barrel heating taking into account its melting and removal of thermal ablation products into the medium inside the bore is solved in a coupled formulation. Heat and mass transfer and friction on the barrel surface are calculated using empirical dependences. The deformable piston is considered compressible and elastoviscoplastic. Allowance is made for the presence of a clearance between the lateral surface of the piston and the barrel bore walls and the associated gas flow between the firing and the light-gas chamber. Calculation results are given.

The physical and chemical phenomena involved in the ballistic process, both in conventional guns and in electrothermal-chemical (ETC) guns, are very complex, so that optimization of gun performance requires a detailed understanding of the influence of different parameters. The initial stage of propellant ignition is critical to the rest of the process, in terms of both performance (muzzle velocity, repeatability) and safety. A better understanding of the ignition stage is thus very important in achieving improved performance. In this paper, we propose a new method and ignition sensor aimed at providing direct experimental information about the propellant ignition process. We further report on measurements of the ignition delays, and the propagation of the "ignition wave", performed using these sensors in experimental devices such as closed bombs and gun simulators.

We apply two-wavelength phase shifting interferometry to generate 3D surface profile maps of spent bullet cartridge cases. From the captured interferograms, an optimized algorithm was used to calculate a phase profile from which a precise digital surface map of the cartridge casing may be produced. This 3D surface profile is used to enhance a firearms examiner's ability to uniquely identify distinct features or toolmarks imprinted on the casing when the weapon is fired. These features play a key role in the matching process of ballistic forensic examination.

A new gas gun technique has been developed in which a small mass fragment is impacted in a precise orientation by a thin metal disk and then recovered. The metal disk is placed inside a hollow sabot that also contains a miniature soft-recovery chamber. After impact, the sabot with the fragment inside is recovered in rags. The fragment will be found either in front of the impactor disk or behind it in the soft-recovery chamber, depending upon whether the disk was perforated. This technique can be used to determine accurate ballistic-limit velocity measurements for fragments with masses less than 0.6 gm. Thirty-six experiments have been performed using this technique for masses in the 0.2–0.6 gm range. Results are presented for several experiments.

The dual objective of developing the present ballistic model is to predict an accurate force-time history in a monolithic thick plate due to penetration by a projectile, and to analytically describe the physical phenomena that occur during a penetration experiment in conjunction with measuring the physical parameters. The analytical model developed considers the evaluation, and prediction of the following quantities: (a) shape and size of the cavity, (b) residual strength of the target, (c) depth of penetration in the target, (d) residual length of the projectile, (e) pressure distribution along the cavity wall and (f) force-time history for the penetration event.

Herein, we study the technique of improving the gun performance by installing a diaphragm in the pump tube of the gun. A CFD study is carried out for the 0.28 in. gun in the Hypervelocity Free Flight Radiation (HFF RAD) range at the NASA Ames Research Center. The normal, full-length pump tube is studied as well as two pump tubes of reduced length (approximately 75% and approximately 33% of the normal length). Significant improvements in performance are calculated to be gained for the reduced length pump tubes upon the addition of the diaphragm. These improvements are identified as reductions in maximum pressures in the pump tube and at the projectile base of approximately 20%, while maintaining the projectile muzzle velocity or as increases in muzzle velocity of approximately 0.5 km/sec while not increasing the maximum pressures in the gun. Also, it is found that both guns with reduced pump tube length (with diaphragms) could maintain the performance of gun with the full length pump tube without diaphragms, whereas the guns with reduced pump tube lengths without diaphragms could not. A five-shot experimental investigation of the pump tube diaphragm technique is carried out for the gun with a pump tube length of 75% normal. The CFD predictions of increased muzzle velocity are borne out by the experimental data. Modest, but useful muzzle velocity increases (2.5 - 6%) are obtained upon the installation of a diaphragm, compared to a benchmark shot without a diaphragm.

In this paper the authors present their activity in the field of electromagnetic machine applications for aerospace solutions. A three stage electromagnetic accelerator is under construction to perform ballistic characterization of carbon-based nanocomposite materials for anti-debris application. Preliminary experiments as well as numerical simulation have been performed with promising results in terms of bullet's energy. Further implementation are needed in order to come closer the velocity of typical space debris (8km/s).

This paper examines the relationship between ballistic factors and bacterial distribution along a surrogate wound channel using ballistic gelatin cylinders with dimensions representative of the calf region of an average human leg. The ballistics factors considered were projectile caliber and speed, and Escherichia coli (E. coli) was used as the representative bacteria. In order to reduce the possibility of contamination by outside bacteria, the E. coli first underwent a transformation protocol to express Green Fluorescent Protein (GFP) and become resistant to the antibiotic ampicillin. A set volume of bacteria was pipetted onto a small piece of filter paper which was placed on the surface of a ballistic gelatin cylinder and a projectile was shot through the bacteria saturated filter paper. The ‘wound track’ was divided into slices, and the area surrounding the permanent cavity was removed with a biopsy punch, liquefied, and grown on selective LB media containing ampicillin. Examination of the bacterial colony count along the permanent cavity segments allowed comparison of how variations in projectile caliber and speed affected contamination distribution along the ‘wound track’. Initial results indicate that larger calibers may result in higher contamination distribution at the projectile entrance and exit regions and higher speeds compress the distribution and result in a drop in contamination level near the exit.Copyright © 2010 by ASME

Flat, hemispherical and ogive-2 nosed mild steel projectiles (10 mm diameter, 100 mm length) were fired at 200 m s{sup -1} into the end face of cylindrically confined dry sand (100 mm diameter, 150 mm length). Projectiles were tracked through the sand using flash radiography and high speed photography. By seeding a horizontal plane of randomly dispersed lead shot (

Proof-of-principle experiments of in-tube propulsion in which the propellant was supplied from the launch tube wall were conducted. The launch tube had a 25 mm × 25 mm square inner cross-section. A pair of opposing launch tube walls were made of polyacetal (POM), which was ablated using repetitive Transeversely-Excited Atmospheric (TEA) CO2 laser pulses. The laser beam was sent through a ZnSe window at the tube bottom to the symmetric parabolic surfaces of the projectile, and focused onto the ablator surfaces. The momentum coupling coefficient was measured from a vertical launch trajectory. When the breech of the launch tube was plugged, a momentum coupling coefficient of 4 mN-s/J at least was obtained. Even when the breech was connected to a vacuum chamber at a pressure lower than 20 Pa, the projectile could be vertically launched with a constant momentum coupling coefficient of 0.14 mN-s/J, the value of which was the same order as that obtained by directly irradiating a laser pulse onto a POM ablator.

International audience; We report a case with an atypical entrance wound as a result of a destabilized full metal jacket bullet penetration. The destabilized bullet by an impact with the dorsal hand experiences a yawing to tumbling motion in flight. The large angle of yaw induces a larger presenting profile upon impact that contributes, associated to a rapid deceleration, to a greater mechanical force on the projectile structure and a fragmentation into core and jacket. Forensic pathologists have to be aware that the metal jacket bullet could tend to break up outside or inside the body particularly after a shooting through a target. This phenomenon induces atypical entrance wounds and atypical X-ray presentation.

Recent requirements for hypervelocity projectile launch for strategic U.S. Army missions have led to the proposal of a variety of gun propulsion systems. Among these systems are those that utilize solid propellant along with electrothermal-chemical (ETC) augmentation. Advanced solid propellant systems with complex grain geometry and loading configuration are also being investigated. In response to this need, the U.S. Army Research Laboratory (ARL) has, for a number of years, engaged in the study of solid propellant ignition using a hot, low molecular-weight plasma generated by ETC means. In addition, ARL is developing an ETC modeling capability using the next-generation interior ballistics code, NGEN, and a series of experimental studies in a ballistic simulator to generate code validation data. The current report demonstrates progress for application of the NGEN code to solid propellant, direct-fire gun systems in which various propellant configurations (i.e., grains and disks) are combined into a single charge in order to obtain higher-loading densities. The charge is ignited using the efflux from an ETC plasma capillary made of polyethylene. Comparison with pressure data measured in a 25-mm ballistics simulator, filled with disks of JA2 propellant as the main charge and a small amount of inert grains as filler, provides validation of the NGEN model with respect to the representation of the plasma efflux from an ablation capillary, into the chamber, and around propellant disks.

A new high temperature transducer is described. The transducer employs NiCr-NiSi thermocouple as a sensing-element and can directly measure flash surface temperature at 1230/spl deg/C under high pressure up to 400 MPa. It can be reused by abrading the hot-junction after it ablated. The response time constant is less than 1 /spl mu/s which was verified by theoretical calculation and by a calibrated test. This paper relates to the features of the transducer and the technology keys to the design of high-pressure-withstand poles, micrometer-order clearance between poles and high-resistance insulation. The theoretical analysis and calibration test are presented. The measurement results and curves of the inner-barrel surface temperature for a certain gun are given. >

The Army Research Laboratory has developed a scaleable, 3D, multiphase, computational fluid dynamics (CFD) code with application to gun propulsion (interior ballistics) modeling. The NGEN3 code, which incorporates general continuum equations along with auxiliary relations into a modular code structure, is readily transportable between computer architectures and is applicable to a wide variety of gun propulsion systems. Two such systems are the Army's Modular Artillery Charge System (MACS) and the Future Combat System (FCS). The MACS is being developed for indirect fire cannon on both current and developing (e.g., Crusader) systems. The efficiency of the MACS charge is dependent on proper flamespreading through the propellant modules; a process that has been repeatedly demonstrated in gun firings, successfully photographed using the ARL ballistics simulator, and numerically modeled using the NGEN3 code. The FCS requires weapons systems exhibiting increased range and accuracy. One of the technologies under investigation to achieve these goals is the electrothermal-chemical (ETC) propulsion concept, in which electrically generated plasma is injected into the gun chamber igniting the high-loadingdensity (HLD) solid propellant charge. NGEN3 code development and application to the MACS and FCS is currently a DoD HPC Challenge Project (No. 112) and is being greatly advanced by access to the DoD high performance computers (HPCs). Associate Fellow AIAA. Propulsion Physics Team Leader, Ballistics and Weapons Concepts Division, Weapons and Materials Research Directorate. Mechanical Engineer, Propulsion Physics Team, Ballistics and Weapons Concepts Division, Weapons and Materials Research Directorate. This paper is declared a work of the U.S. Government and is not subject to copyright protection in the United States. INTRODUCTION A solid propellant gun system consists of a reaction chamber connected to a gun tube through which a projectile is guided once propelled by pressurization of the chamber. Chamber pressurization is accomplished by placing a solid propellant (SP) charge in the chamber and igniting it by various means. Current SP charges are generally complex structures consisting of hundreds or even thousands of distinct regularly formed (e.g., spherical, cylindrical) grains, which may be loaded in either regular or random arrangements. In addition to small-scale voidage between grains (i.e., porosity) many charges also contain large-scale voidage (i.e., ullage), which surrounds the entire charge (such as when the charge does not fill the entire chamber volume) or separates distinct subcharges (i.e., increments or modules) that together comprise the whole charge. The addition of energy to the chamber, usually near the gun breech, or rearmost end of the chamber, and in some cases through a tube extending along the centerline of the chamber, ignites the SP. In general, all of the grains are not ignited simultaneously, but an ignition flame spreads from the breech to the projectile base. The burning of the SP transforms chemical energy into heat as hot gases evolve from the surface of each grain of propellant. Initially the projectile resists movement allowing the pressure in the chamber to climb rapidly. Since the burn rate of the propellant is proportional to the pressure, hot gases are produced at an accelerated rate until peak pressure is reached in the chamber. Movement of the projectile down the gun tube, usually slight before peak pressure and much more significant afterwards, causes the chamber volume to increase, and generates rarefaction waves, which lower the pressure and thus the burn rate of the propellant. Upon ignition and burning, the gas dynamic flowfield in the gun chamber takes on a highly complex structure that includes the dynamics of propellant motion and combustion and various gas dynamic flow phenomena such as turbulent mixing, highly transient pressure waves, steep gradients in porosity and temperature, nonideal thermodynamics, and gas generation.

The new technique of digital speckle X‐ray flash photography (DSXFP), which has been successfully applied to polyester and cement specimens, is being further developed and used to study materials in ballistic situations in a way not previously possible. The technique involves seeding the specimen with a lead layer and then taking flash X‐ray images before and during an impact event. Digital cross‐correlation can then be used to make measurements of the internal displacements occurring throughout the specimen. Using a stereoscopic geometry the out of plane displacements can also be determined and a full 3‐dimensional displacement map constructed. In this paper these two powerful and complementary techniques of flash X‐rays and DSXFP are used to study the ballistic response of a borosilicate sample to produce information that other techniques are unable to provide.

Non-invasive detection methods for tracking gun-launched projectiles are important not only for assessment of gun performance but are also essential for timing a variety of diagnostics, for example, to investigate plate-impact events for shock compression experiments. Measurement of the time of passage of a projectile moving inside of the gun barrel can be achieved by detection of the transient hoop strain induced in the barrel of a light-gas gun by the passage of the projectile using external, barrel surface-mounted optical fiber-Bragg grating strain gauges. Optical fiber-Bragg gratings have been implemented and their response characterized on single-stage and two-stage light gas guns routinely used for dynamic experimentation at Los Alamos National Laboratory. Two approaches, using either broadband or narrowband illumination, were used to monitor changes in the Bragg wavelength of the fiber-Bragg gratings. The second approach, using narrowband laser illumination, offered the highest sensitivity. The feasibility of using these techniques to generate early, pre-event signals useful for triggering high-latency diagnostics was demonstrated.

Since 1985 low power (10 - 20 W) copper lasers have been used widely as a high performance strobe light for High Speed Imaging. In this area it has found applications in ballistics [1], flow visualisation [2], spray analysis (especially of fuel spray within combustion engines) [3-4] and more recently in the visualization of materials processing [5]. Most of these applications make use of the ability of copper lasers to run at very high repetition rates. Commercial lasers are available which operate at up to 32 kHz and experimental systems have operated to even higher rates.Since 1985 low power (10 - 20 W) copper lasers have been used widely as a high performance strobe light for High Speed Imaging. In this area it has found applications in ballistics [1], flow visualisation [2], spray analysis (especially of fuel spray within combustion engines) [3-4] and more recently in the visualization of materials processing [5]. Most of these applications make use of the ability of copper lasers to run at very high repetition rates. Commercial lasers are available which operate at up to 32 kHz and experimental systems have operated to even higher rates.

A multiple-laser flash shadowgraphy system has been innovatively designed and developed to study the terminal effects of projectiles. The system has been designed based on modulated laser diodes operated at low voltage and current. In order to study the ballistics effects of small arms, an exposure time of the order of a few hundreds ns and a delay time of the order of a few tens of μs are needed. An ultrashort pulse generator has been developed to provide the exposure and delay time pulses. The developed system has been integrated with a field lens assembly and camera assembly. To record the shadowgraphs, a target is placed near the center of the field lens and a bullet is fired from a fixed gun. The system is described, and experimental results and conclusions are reported.

A new microvelocity sensor unit was developed to measure the instantaneous velocity of a high velocity impactor during the penetration process. The concept of this device is based on the induced current generated in a coil due to the passage of a magnet. A special digital circuit was designed to yield a spatial resolution of better than 0.05 in. by eliminating the problem of signal overlap. The precise time delays obtained from these signals can be used to determine the slowing down or energy loss of a high‐velocity projectile. The details of this sensor unit will be described and its resolution will be demonstrated. A light gas gun was used to propel aluminum projectiles to velocities up to 320 m/s. Energy loss of these high‐velocity projectiles in composites reinforced with polyethylene, polyester, and graphite fabrics as well as pure Kevlar fabric was measured using this system. Results show that this microvelocity sensor is capable of identifying various energy‐loss processes during the impact of high‐velocity projectiles.

A multiple ruby laser system is used to provide intense, extremely short (30 ns) highly monochromatic light pulses for high speed photography. The light output from the lasers is transmitted to the two optical systems with fiber optic light guides. The ruby lasers are employed with a conventional Cranz-Schardin system in dynamic photoelastic studies of stress waves and in studies of crack branching in tempered glass. The ruby lasers are employed with an unorthodox Cranz-Schardin system in ballistics studies of armor penetration. Of particular importance is the use of a microprocessor which provides precise synchronization by computing in real time the anticipated arrival time and controlling the Q-switching of the lasers. Variations in projectile velocity due to projectile weight, charge density, and drag are accommodated by programming the microprocessor.

Test firings of prototype fin- and flare-stabilized 25 mm training rounds were conducted. The fin-stabilized rounds were found to be capable of fulfilling all of the training round ballistic requirements. The flare- stabilized rounds were studied as a possible lower cost alternative. Initially, a large angle flare design, similar to existing tank gun training round, was tested, but data showed the configuration drag coefficient was too high. Subsequent computer predictions indicated that a small angle flare would have significantly lower drag and sufficient stability for flight. A four-degree flare was fabricated and fired, confirming the drag and stability predictions.

We have developed and used an optical-fiber sensor for detecting the arrival of strong pressure pulses. The sensor consists of an optical fiber, tipped with a gas-filled microballoon. They have been used successfully in adverse environments including explosives, ballistics and electromagnetic pulses (EMP). The sensor produces a bright optical pulse caused by the rapid shock-heating of a gas, typically argon or xenon, which is confined in the spherical glass or plastic microballoon. The light pulse is transmitted via the optical fiber to a photo detector, usually a streak camera or photomultiplier tube. The microballoon optical sensor (called an optical pin by analogy to standard electrical pins), was originally developed for diagnosing an explosive, pulsed-power generator. Optical pins are required due to the EMP. The optical pins are economical arrival-time indicators because many channels can be recorded by one streak camera. The generator tests and related experiments, involving projectile velocities and detonation velocities of several kilometers per/sec have demonstrated the usefulness of the sensors in explosives and ballistics applications. We have also measured the sensitivity of the optical pins to slowly-moving projectiles and found that a 200 m/sec projectile impacting the microballoon sensor produces a flash having a risetime less thanmore » 100 ns and a pulse duration (FWHM) of less than 300 ns. The technical and cost advantages of this optical pin make it potentially useful for many electromagnetic, explosive, and ballistics applications.« less

The tests reported here were conducted to determine the effects produced on the ballistics of a liquid monopropellant round by advancing the point of venting of the primer within the propellant column. The tests were conducted with two case configurations in which the L/D ratios of the propellant columns were approximately 3.4 and 5.0. As the point of venting was advanced, muzzle velocity increased in rounds with the L/D ratio of 5.0, but decreased in those with the L/D ratio of 3.4. The amount of unburned propellant remaining in the case after firing increased in both case configurations. In both configurations, the pressure curves were transformed from curves with two distinct pressure peaks, through stages approximating plateau configurations, to curves with one well defined pressure maximum.

A new single-stage, high-pressure, stainless steel, light-gas gun 30 ft long with a 1 3/8-in. bore has been designed and built at DOFL. This gun has driven a 6-gm mass at velocities above 5000 fps. With alterations made to heat the driver section, it is expected to give velocities of over 8000 fps and make possible impact shock pressures of more than 1-megabar. A comparison of the measured and computed projectile velocities at room temperature as well as higher temperatures is included.

A feasibility study of a smoke or vapor stream system to function in the nose cone of a fin-stabilized round was conducted. The conventional base-located system could not be used because (a) the round contained a discarding sabot mechanism, and (b) the vibration, jolt, and dust following the discharge of the large vehicle-mounted gun would cause the gunner to momentarily lose sight of the missile. Hence, a persistent trail observable by daylight was needed. Titanium tetrachloride was tried because, on exposure to air, it forms dense white clouds of titanium hydroxide. However, the corrosive properties of this material made it difficult to package. Since calculations indicated that nose temperatures exceeding 300 deg C would be attained during projectile flight, a new approach using a heat sensitive initiator was formulated. Diazodinitrophenol (DDNP), which ignites after 0.25 second of flight (200 deg C) was pressed into the nose cone tip assembly. A conically shaped red smoke composition was inserted directly behind the DDNP. Two holes drilled near the apex of the cone body allowed the generated smoke to escape. This approach worked satisfactorily in static tests. In ballistic tests, however, the smoke composition was ejected as a puff of red smoke with no streaming.

Various aspects of the perforation of thin targets by high speed fragments were investigated. A fragment projector yielding compact steel fragments having a velocity of 3.17 km/sec and a mass of .0234 g was generally used for experimental studies. Design features of this projector are presented with methods of attaining higher velocities. The volume and shape of craters produced in lead at 60 degrees obliquity by fragments having a velocity of 4 km/ sec are compared with the characteristics of craters produced at impact velocities of 3 km/sec and 5 km/sec.