Search

The need to forensically search soil for small artefacts at a burial site or traces of evidence in a deposition site is a common task shared by investigators and forensic archaeologists. In forensic casework, the importance of finding small pieces of evidence, such as personal effects or ballistic fragments, cannot be overstated as it can assist in the positive identification of the deceased, give an insight into the manner and cause of death, and identify any perpetrators. The soil search methods known as wet and dry sieving, are cumbersome, time-consuming and have limited success for some soil types. This often leads to the decision not to search, resulting in missed opportunities to identify potential evidence. The primary aim of this study was to investigate if a dual energy X-ray baggage scanner could be used to search for items of potential forensic interest in soil. A trial was conducted using a Smiths Detection ScanTrailer 100100 V-2is mobile X-ray inspection system to establish if it could be used to detect organic, inorganic, and metallic items located within soil. The soil type and natural variables such as water and organic content were adjusted to simulate different environments. The baggage scanner was found to provide a quick and easy way to detect items contained within various soil types, particularly in a sand rich matrix. It is estimated that using this method to search 1 msup3/supof soil, when broken down into samples that are lt; 13 cm in depth, would take around one hour to complete, compared with 100 to 150 person-hours by manual sieving. This is believed to be the first use of dual energy X-ray technology for this purpose and shows the potential for further research and use of this method in forensic archaeology.

Materials capable of oxidizing in a protective manner at ultrahigh (>1700 °C) temperatures are needed to push beyond this barrier defined by SiC. Although possessing attractive mechanical properties and oxidation resistance, SiC-based materials are ultimately temperature limited by the melting point of SiO2. The vast array of ultra-high and high temperature ceramic literature indicates the majority of these materials, like borides, carbides, MAX-phases, and high-entropy ceramics, fall woefully short regarding oxidation resistance. However, for specific applications, like low-orbit aeropropulsion, high ballistics coefficient atmospheric re-entry, and hypersonic cruise, there are a few promising materials. In the present review, oxidation criteria are gathered to build application specific heuristics and are then applied to a multitude of ultra-high temperature ceramics to gauge material efficacy. Discussion of oxidation kinetics, mechanisms and reaction products is offered for each material, identifying strengths, weaknesses, and the remaining gaps in our knowledge.

Application of the method of removal of space debris objects by an ion beam - the IBS method - seems to be the most effective for cleaning the GEO region. This is due to the low energy consumption for transfer one object in a safe orbit delta-V≃11 m/s and the possibility of removal several objects by one spacecraft. The service spacecraft for this purpose can be developed on the basis of telsat technology, taking into account its functions. Such a spacecraft should contain an ion beam injector to act on the removed object and an electric propulsion system, which serves to compensate for the ion injector thrust and to control the spacecraft motion both during transportation of the removed object and during interorbital flights. The development of a weakly diverging ion beam injector, determination of the composition and structure of an electric propulsion system, ballistics of the optimal sequence of interorbital flights, and development of an algorithm for controlling a virtual cluster: spacecraft-removed object are discussed in the article. In the majority of works on IBS, commercial ion thrusters are considered as an ion injector and engines. However, ion beams from ion thrusters have a half angle of divergence of 120-150. When propagating in outer space, the ion beam expands irresistibly due to electron thermal effects. As a result, the distance at which the spacecraft must follow the removed object during its transportation for effective impulse transmission to it should be small (estimated, about 7 m). Taking into account the dimensions of both objects and the uncontrolled movement of the removed object relative to its center of mass, the object transportation operation carries noticeable risks. The results of an experimental study of a prototype of an ion injector with an initial half angle of divergence of 20-40 are presented. The use of such an injector would provide a distance between objects of 15–20 m and reduce the risk of their collision. In connection with IBS, various aspects of spacecraft control during transportation of an object with one, two or more engines as part of the electric propulsion system are considered. In the conceptual design of the spacecraft presented in this work, the electric propulsion system contains two stationary plasma thrusters, each of which is mounted with the possibility of independent rotation respect to two mutually perpendicular directions. Spacecraft motion control, including thrust vector control, is carried out by means of the thrusters coordinated rotation. The characteristics of the spacecraft and its subsystems intended for the removal of several objects are conceptually considered. For example, parameters of the mission for the removal of up to 10 objects from the NORAD catalog from the GEO region are given. In the future, using the result obtained, the control of SC of this scheme when IBS implementing in the low-Earth orbit will be considered.

A vast majority of widely accepted granular segregation mechanisms are attributed to dynamic phenomena such as percolation, kinetic sieving, convection-induced segregation, condensation, inertia and granular temperature gradients. We distinguish the ballistics of the particles from such dynamic and material properties and show that the former is a dominant mechanism in the segregation of particles sedimented in a container. We first perform granular sedimentation experiments with glass beads in water that exhibit size-segregation of bidisperse grains. We then show through simulations using a simple, first-order model that the ballistics of the particles alone is sufficient to qualitatively predict this segregation.

Firearm offences in the UK, though not as high as in the USA, are increasing year upon year within both countries (Office for National Statistics, 2018 & Mervosh, 2018). This preliminary study looked into using Micro-CT scanning as a method to visualise impact damage and spray patterns caused by 12 test firings of both round and flat nosed bullets to porcine bone (shoulder and leg) suspended in ballistic gelatine and left with no covering, covered with a skin substitute, or covered with fabric (cotton or denim). Micro-CT scanning alongside VG Studio Max showed that overall, in the case of the shoulder bones the round nosed produced longer spray patterns (35.37 mm) within the gelatine blocks compared to the flat nosed bullet (27.33 mm); while with the leg bones the spray patterns were shorter, round nosed bullet (15.64 mm) and the flat nosed bullet (20.78 mm). These initial results showed that both bullet types produced considerable damage, from splitting to full penetration, which in turn illustrates how Micro-CT scanning has benefits within forensic ballistics, which should be further investigated.

Quality practices in forensic science are often in tension with providing timely results. When the Costa Rican Department of Forensic Sciences ballistics unit achieved accreditation under ISO/IEC 17020:2012 in 2018, the unit started experiencing slower turnaround times. With a view to expediting the resolution of forensic examination processes, the unit undertook a Lean Six Sigma project with a five-phase problem-solving methodology. The unit began to use data and process tools to transform its current state. The completion of all phases showed that two main aspects were preventing the laboratory from fulfilling the customers’ expectations: standardization and constraints. This project took 6 months and improvements were seen through the reduction of the number of pending cases with a backlog of more than 3 months by 97% and the turnaround time from 4 months to 1 month. Through this project, leadership identified an effective methodology, creating a positive impact on customers’ expectations.

This paper presents a method for obtaining time dependent back face deformation (BFD) data for body armor during ballistic impact using a clear ballistics gelatin backing and high-speed cameras to capture the deformation profile. Using this method, baseline fabric characterization data was obtained for samples comprised of varying layers of 467 g/m 2 Kevlar K29 fabric impacted with 8.24 g steel ball projectile and backed with NATO standard 20% clear ballistics gelatin. For these tests, deformation depths were seen to increase with increasing impact energy and decreasing total areal density. A limited study of the various test parameters was performed by testing one additional fabric, projectile, and ballistics gelatin. From these comparisons, it was observed that 122 g/m 2 Kevlar KM2+ fabric performs better per weight than 467 g/m2 Kevlar K29 fabric in terms of BFD, 9 mm FMJ projectiles produce deeper BFDs than 12.7 mm steel ball projectiles, and backing a sample with FBI standard 10% ballistics gel increases the BFD considerably over NATO standard 20% ballistics gel.

In order to achieve multi-objective optimization design of ballistics and improve the power of weapons, an optimization model for the internal ballistic simulation design of the propellant charge was established. Based on the requirements of artillery ballistic performance, the model took several influences into account, such as type, charge mass (ω) and web thickness (2e1). The objective function was composed of muzzle velocity (v0), maximum chamber pressure (pm), relative burnout point (ηk) equations. The computational program used recursive algorithm to calculate and select reasonable charge results by looping the internal ballistics and optimization design equation sets. 105 mm artillery and 122 mm artillery were selected as examples to optimize the charge design. The results show that compared with the existing charging scheme, the loading scheme optimized by the model can reduce the relative burnout point of 105 mm artillery by 0.21 in the case of the muzzle velocity, and the maximum chamber pressure have a little difference. The maximum chamber pressure of the 122 mm artillery reduces by 2.83% while the muzzle velocity increases by 1.13%.

The one-by-one examination of the increasing Open Case File (OCF) archive by comparison macroscope has become a time-consuming process and the last quarter of the 20th century witnessed the development of automated ballistic identification systems. After the utilization of these systems, government institutes, scholars and the companies devising such systems conducted various performance tests to analyze duration and correlation. The performance of BALISTIKA and similar automated firearms identification systems are frequently measured using the pistol cartridges. This study brings a new perspective to automated ballistic identification system performance tests through using same and different brand steel 7.62×39 mm cartridge cases. The performance of BALISTIKA system was measured using 4387 comparison cartridge cases according to breech face, firing pin, ejector marks and combined evaluation criteria. It was determined that correlation performance of BALISTIKA for the same brand cartridges are higher and ejector marks are the most distinct matching criteria for 7.62×39 mm steel cartridge cases. The test results are presented under the headings of weapon-manufacturer countries, automated ballistic identification system matching criteria for both same and different cartridge brands.

In molecular ballistics, the molecular genetic analysis of biological material is integrated with the biophysical wounding events and trace investigations of terminal ballistics. It aims to support the objective, evidence-based reconstruction of gun-related crimes. Of central interest is the analysis of backspatter traces: biological material propelled back from the entry site of a bullet after impact on a biological target. This study is a first approach to systematically investigate possible correlations or patterns between the amount of recoverable DNA (yield) from backspatter traces found on and inside fired guns and the shooting distance. After firing shots from five distances (0, 5, 10, 15, 30 cm) with both a pistol and revolver in triplicates, no clear correlations or patterns can be observed, due to considerable variation between measurements from identical triplicates and a lack of linear relation between distance and yield, e.g. yields from even 30 cm shots will sometimes exceed those of contact shots. Wound channel evaluation was performed as well and distinct differences between contact shots and distance shots could be observed, but not between any distant shots.

Ground stone projectile points can be found throughout the global archaeological record, but why they were selected for by prehistoric foragers has received little attention. Additionally, modern archaeological experiments have increasingly used ground points in lieu of knapped ones. Here, we present an experiment testing whether there is a difference between ground, percussion flaked, and pressure flaked points in terms of impact durability. Our three groups were similar in form, raw material, and hafting, only differing in their production. Controlled ballistics tests demonstrated that ground stone points did not break at a different rate than either the percussion flaked or pressure flaked points, nor was post-firing point length (as a percentage of original point length) different. These results are consistent with the hypothesis that impact durability on its own was not likely a motivating factor for forager selection of grinding versus knapping. Instead, researchers should look to other factors, such as skill, demography, time budgets, or raw material selection to explain the emergence of ground stone points in particular contexts. Given our null results, our test also supports the use of ground stone points in modern archaeological experiments.

In this paper, the effect of the chemical composition of .22LR bullets was studied and correlated to the extent and quality of the markings left after shooting them with the same gun. Scanning electron microscopy and optical comparator microscopy equipped with 3D and profilometry modules were used as non destructive techniques with two main purposes. The first is to assist the firearm examiner in the choice of the ammunition most suitable for preparing the test bullets. The second is to propose an approach, crossing data from optical microscopy, profilometry and space-resolved chemical analysis, for explaining the morphology of striae, whether continuous or interrupted. Among the most notable results is the finding that commercial .22LR ammunition show very wide interbrand, interlot and intralot variability. A selection of test ammunition solely based on the same brand and model used on the crime scene is therefore not suitable, urging the need for a more accurate choice, based on a preliminary chemical analysis.

Ballistic traumas are defined by a projectile entering the body. Such projectiles include bullets, birdshot, and metal fragments from the covering or the contents of an explosive device. They frequently cause severe wounds characterized by a range of clinical pictures and a large spectrum of concomitant wounds. The major aims of imaging are to define the path of the projectile or projectiles, to evaluate which tissues have been injured, to estimate the severity of injury, and to determine what additional studies are needed. A routine radiograph is performed in patients with gunshot wounds. The diagnostic approach has been changed by the use of multidetector row computed tomography (MDCT) due to its technical developments particularly faster data acquisition and advanced image reconstructions. In the evaluation of patients with gunshot injuries, MDCT is considered the method of choice to identify hemorrhage, bullet, bone fragments, air, hemothorax, nerve lesions, musculoskeletal lesions, and vessel injuries. Moreover, MDCT technology and multiplanar reformation postprocessing allow meticulous trajectory analysis that potentially benefits the clinical outcomes of patients aiding time-saving triage and correct image-based diagnosis of organ and vessel damage. Familiarity of ballistics and forensic sciences will therefore help the radiologist in assessment and localization of the damage caused by projectiles.

Highlights • Ballistic tramatology in the upper humerus extremity region presents challenging management difficulties. • Resurfacing shoulder hemi arthroplasty in ballistic injuries is not commonly reported. • The indication of resurfacing shoulder hemi arthroplasty was appropriate regarding good functional outcome., Introduction Ballistic traumatology of the shoulder joint is uncommon. Usually, it is associated to comminuted fractures of the upper humerus. Total shoulder arthroplasty has been proposed to restore a good function. The indication of resurfacing hemi arthroplasty still controversial and is not commonly reported after ballistic traumatology. Presentation of case We report the case of a 26-year-old soldier victim of a gunshot of the left shoulder entailing a comminuted complex fracture of the upper extremity of the humerus. After shoulder immobilization of 3 months joint mobility was very limited. Radiographs showed bone malunion with a total loss of the hemispherical form of the humeral head. Patient has undergone a resurfacing hemi arthroplasty. Surgery outcome was good. At five years of follow-up, there were no major functional complaints. Clinical and radiological result was satisfactory with a good shoulder mobility. Discussion Shoulder arthroplasty provided good functional outcome in case of post fracture sequelae. Difficulty was to choose between total arthroplasty and hemi arthroplasty. In young and active patients, authors disapproved total arthroplasty in post traumatic gleno-humeral arthrosis to prevent revision difficulties especially after glenoid erosion. Conclusion Although follow-up still be limited, the indication of shoulder hemi arthroplasty was appropriate regarding functional outcome and patient satisfaction. Further clinical and radiological supervision still necessary to detect glenoid erosion.

In the field of ballistics, Johnson-Cook (JC) plasticity and fracture models have provided a good theoretical basis for the prediction of ballistic performance by capturing the essence of ductile metal fracture. Nevertheless, the JC model cannot accurately reproduce the fracture behaviour of some metals. Many Lode parameter-dependent fracture criteria have effectively improved this deficiency, indicating that the fracture loci of these metals are Lode-dependent, even though the flow stress behaviour is stress state dependent, which cannot be well characterized by the JC plasticity model. In this paper, a series of mechanical tests and parallel numerical simulations of ZK61m magnesium alloy were conducted. The results showed that the flow stress behaviour and fracture loci of the alloy were obviously Lode dependent. Therefore, it seems insufficient to evaluate only the necessity of incorporating Lode parameter into a fracture criterion in predicting ballistic performance of ZK61m magnesium alloy, and more investigations on the influence of Lode parameter on the plasticity behaviour of the material should be carried out. In the present work, ballistic tests were conducted on 5 mm thick ZK61m magnesium alloy plates using blunt and ogival nose shaped projectiles with a nominal diameter of 12.68 mm. The targets failed by shear plugging when impacted by blunt-nosed projectiles, but caused a unique failure pattern under the impact of ogival-nosed projectiles. Lode-dependent plasticity model and fracture criterion were adopted. Better prediction accuracy was observed when Lode parameter is considered in both the plasticity model and fracture criterion simultaneously.

A dynamical moving pressure structural numerical calculation model using the internal ballistics calculation pressure-time results was constituted and the vicinity of the internal ballistics and quasi-internal ballistics structural model was checked. The Von Mises stresses obtained by the dynamical structural numerical model calculations and the Von Mises stresses calculated from the shot test strain measurements were compared. The difference for the worse case was 20% and for the best case was 0.1%. Furthermore, the model gave better agreement for the higher charge masses. The numerical structural quasi-internal ballistics computation model created was verified for the top charge mass which represents the highest stress condition and used in a gun barrel design. Keywords: Gun tube design, Thick wall cylinder, Residual stress, Internal ballistics, Service pressure, Wall thickness, Numerical modeling of internal ballistics

Powdered Mg and CO2 bipropellant engine providing a practical demonstration of in situ resource utilization (ISRU) for Mars Sample Return (MSR) mission seems to be feasible by current investigations. However, essential functions of the engine to satisfy the complicated ballistics requirements such as thrust modulation and multiple pulse have not been established yet. The aim of this experimental study is to evaluate the engine's thrust modulation feasibility and to investigate its thrust modulation characteristics. A powdered Mg and CO2 bipropellant engine construction aiming to achieve thrust modulation ability was proposed. A mass flow rate calibration experiment to evaluate the gas-solid mass flow rate regulating performance was conducted before fire tests. Fire test result shows that the engine achieved successful ignition as well as self-sustaining combustion; Thrust modulation of the engine is feasible, detail thrust estimating result of the test shows that maximum thrust is 135.91 N and the minimum is 5.65 N with a 22.11 thrust modulation ratio, moreover, the transportation period is quick and the thrust modulation ratio is adjustable. At the same time, the powder feed system reaches a two-step flow rate regulating with a modulation ratio of 4.5–5. What’ more, caused by the uneven engine working conditions, there is an obvious difference in combustion efficiency value, maximum combustion efficiency of the powdered Mg and CO2 bipropellant engine is 80.20%.

The ricochet behaviour of AK bullets (7,62 × 39 mm), one of the prominently reported bullet type in recent shooting incidents worldwide, has been examined on a range of different wooden surfaces in this study. The critical angles of AK bullets for teak, Jack wood, mahogany and pine were reported with close values ranging from 9.9 to 13.3- degrees, suggestive of being a valuable reference that can be used during AK bullet ricochet-related shooting investigations with similar conditions. The study also highlighted a significant phenomenon against the existing understanding on the wood hardness and the critical angles of bullets. The widths of the AK bullet wipe marks generated on the wood surfaces were highly consistent, regardless of impact angle, allowing an effective approximation of bullet caliber. Bullet tunnelling effect were also observed with pinewood samples in this study. The study also further highlights the great variability of bullet ricochet phenomena and the challenging nature of using the theoretical and experimental results relates to wood ricochet studies for shooting reconstructions.

Small (5.56 mm, 7.62 mm and 9 mm) and medium (12.7 mm) arms rounds were fired at snow-filled 1.5m cubic gabions in a mid-winter condition in Fairbanks, Alaska. The rounds were excavated and penetration by each ammunition type was measured. A distribution and average of penetration depth was determined. All 320 rounds fired were captured within 1.5m after entering the snow barrier. Comparison with published models of ballistics penetration of snow showed mixed results with several matching our data within 10% and all but one within 32%. However, most of these models are simplistic in that they accommodate limited variables and therefore may not be expected to perform well in all settings. We conclude that snow-based ballistics protection structures can be quickly and efficiently erected in suitable environments and with minimal size, can provide reliable protection against small and medium arms fire.

The total entry area of a projectile to the impacted object is a key ballistic parameter of lithic projectiles. Together with the assumed or experimentally testified penetration depth, it forms the first reception of the wounding capability of an individual projectile point, i.e., of the permanent wounding cavity volume. Mathematical operations are used to calculate the entry area, for which the manually measured dimensions of the projectile form input data. Nevertheless, these methods reconstruct only the cross-sectional area at only one point of the longitudinal axis of the object. Here, we propose a method of using high-resolution 3D data for precise measurements of the real entry area of a projectile, even in the case of barbed projectiles whose barbs exceed the width of the projectile body, as well as in cases of projectiles with an asymmetric cross-section. The proposed method of using 3D models to read the numerically expressed values of ballistic parameters was used to analyse almost 400 lithic archery projectiles found in the eastern part of Central Europe, dating from the Late Eneolithic and Early Bronze Age, a culminating period for lithic archery projectiles in the archaeological record.

The Liberator is a firearm that can be manufactured from its blueprints, using a 3D-printer. This weapon made of nineteen pieces - eighteen in printed plastic and one metallic nail - raises questions such as its ability to fire a round, its wounding potential and the traces produced by its discharge. In particular, knowledge must be gained to infer that a 3D-printed handgun was used, reconstruct the shooting event involving such handgun, and gather information related to the type of 3D-printed handgun used. This study focused on the traces that could orientate forensic investigations when the use of a 3D-printed Liberator is suspected. In a first step, the Liberator was investigated to study its behaviour during the discharge and characterize traces produced by the discharge. To fulfil this goal, some Liberators were printed and assembled. Six Liberators fired a round. The discharge of the weapons was done under specific conditions allowing to collect ballistics data and traces produced by the shooting. The results showed that the barrel tended to break between the ignition of the primer and the moment the projectile exited the muzzle. The speed of the projectiles reached 140m/s when the barrel broke, while it was about 170m/s when barrel remained intact. The trajectory of the projectiles was sometimes disrupted, and the projectile tumbled on itself. It was thus very difficult to characterize the trajectory. The cavity wound caused by the fastest bullet was typical of a handgun wound firing a FMJ projectile (penetration of 21cm in ballistics soap). On the other hand, the cavity caused by the slowest bullet was more representative of a splinter wound (penetration of 14cm in ballistics soap). The study of gunshot residues collected on adhesive targets showed the presence of unburnt particles and small perforations caused by polymer pieces that concentrated around the entry holes.

Shear thickening fluids (STFs) are a special class of field responsive non-Newtonian fluids which exhibit transition from low viscosity to high viscosity state when these are subjected to shear deformation, particularly when the shear rate exceeds a critical value termed as the critical shear rate (CSR). Due to this unique characteristic of STFs, these are generally used for vibration mitigation or shock absorbance such as in vibration dampeners, hip protection pads, in protective gear for athletes etc. From the last two decades, STFs have found application in the field of ballistics, particularly in the development of special class of STF-intercalated armours called Liquid Body Armours (LBAs). These new age armours are lighter in weight and more flexible as compared to conventional heavy armours, which, infact seriously affect the mobility and agility of the soldier, especially in combat situations. Although, exhaustive studies are available which show the improvement in impact resistance of STF-treated high performance fabrics, but there are limited studies which explore the efficacy of STF treatment method. In this study, an attempt is made to understand this aspect. The low velocity impact studies were conducted on drop tower machine, while high velocity impact studies were accomplished on in-house designed and fabricated Split Hopkinson Pressure Bar (SHPB) experimental set-up. It was observed that when STF was kept in liquid form between layers of ballistic fabrics, the composite exhibited reduced performance, whereas, STF-treated ballisic composites exhibited enhanced impact toughness at high strain rates in SHPB testing.

Research in the field of wound ballistics has identified three major types of penetrating trauma injuries that will affect wound severity of a projectile point into hard or soft tissues: puncture, incised, and lacerated. In this study, we report on dual ballistics experiments conducted to better understand the wounding mechanisms of three prehistoric projectile point classes made respectfully of polished bone, bifacially flaked stone, and composite antler inset with microblades. Each class of projectiles was launched into ballistics gelatin and into the carcass of a reindeer to explore the relative performance characteristics of each class in terms of tool durability and wound infliction. Our methods of evaluation included a detailed measurement of projectile attributes before and after penetration of both gelatin and carcass that were then compared using tip-metrics, penetration depth, and total interior wound area. Our results strongly suggest that the wounding potential differed significantly between projectile point classes and in turn, strongly influenced wound severity. We suggest that point mechanics may implicate a “prey specific” hunting strategy and propose that such analyses can help us better understand prehistoric hunter-gather behavior and technological variability.

The ballistics equations for spherical pellets in free flight are simplified through appropriate scaling of the pellet velocity and pellet distance. Two different drag coefficient curves are averaged to yield a single curve applicable to shot pellets and round balls. The resulting S-shaped drag coefficient curve is approximated by three straight-line segments. The scaled ballistics equations are then solved exactly and simple formulas are found for the velocity and flight time with respect to trajectory distance. The formulas are applicable to spherical shot pellets and round balls of any composition under any atmospheric conditions. The formulas are amenable to quick and easy computation and may also serve as an aid in understanding and comparing black-box ballistics calculators. For shotshell ballistics, an important assumption in the present investigation is that the pellets are moving as single, free spheres and not as a dense cloud or in a shot column, in particular, the pellets are not interacting during flight. Therefore, the formulas are most appropriate for single round balls, for large shot sizes, and for pellets of small shot size fired from open chokes. The formulas are clear and accessible, and can be implemented by military or law enforcement personnel as well as hunters and shooters. This work differs from previous investigations in that accurate ballistics formulas are derived for spherical projectiles of shotguns and muzzleloaders using realistic drag coefficients.

In this paper the bombardment of the Constantinople Theodosian Walls by the great cannon of Orban is numerically reproduced with the aid of Structural Mechanics. Overall gun dimensions were assessed based on historical reports, whereby, the gunpowder charge p was estimated at 177 kg, and the gun was placed at a distance of 500 m from the Inner Walls. Gun ballistics and effect on target have been evaluated analytically. The analysis has verified Orban’s gun muzzle velocity, cannonball trajectory and its effect on Constantinople Walls by successfully calculating the length of the breach in the wall, referred to in historical reports, as well as the cannon ball penetration into soil. Finally, a numerical effort was made to assess the sound pressure level inside Constantinople during bombardment confirming the tremendous psychological effect of the cannon’s blast on the City’s population.

Gun violence is a global phenomenon with regional variation in frequency and severity. Handguns are often used in violent deaths such as suicides and homicides. Hence, ballistic trauma is a critical subject of forensic investigations. Trauma patterns are fundamental evidence for the reconstruction of the incident and the determination of the manner of death. This study investigated the differences in trauma patterns with a series of experiments using six different calibers (.22 LR, .38 Special, .380 ACP, 9 x 19 mm, .40 S&W, and .45 ACP) and four different bullet types. Synbone® spheres (polyurethane bone proxies) were used for close range (30 cm) simulated executions. The polyurethane spheres constitute an excellent proxy for human crania at the macroscopic level as suggested by other studies. The results showed that the radius of the entrance wound is positively correlated (Pearson’s correlation coefficient R=0.846, p

An experimental study and hydrocode simulation was conducted to investigate the correlation between hardness of steel and the ballistic performance of steel-encapsulated SiC armour modules against long rod impact. The armour module design composed of a SiC tile in confinement within 10 mm backing and 5 mm cover plates, which were made of AISI 4340 steel with varying hardnesses between HRC 30 to 50. The armour modules were subjected to normal impact by conical tungsten alloy long rods of 8.3 mm diameter and 115 mm length, at a nominal striking velocity of 1.25 km/s. A witness block of AISI 4340 steel was placed behind the armour module to capture the residual projectile. Failure analysis of the armour modules and the measurement of residual penetration in the witness blocks were applied to characterize ballistic performance of the ceramic armour modules. The different modes of failure of the backing plate and its influence on ballistic performance of the module were verified through visual inspection of test modules and analysis of high speed videos. Hydrocode simulation of the experiments using LS-DYNA was carried out to model the penetration and failure processes that occurred in the armour modules. The Johnson Cook model was applied in simulation of the steel confinement, accounting for the influence of hardness on JC model parameters. Results showed that increasing hardness of the backing enhanced the performance of the module while cover plate hardness had no influence within the range of hardnesses tested. This study paves the way for future studies to further understand the influence of steel hardness on the ballistics performance of steel-encapsulated silicon carbide (SiC) armour modules.

In this study, we report the effect of preferential sputtering during ion beam machining multicomponent optics. A binary continuum model is developed to investigate the surface preferential sputtering mechanism. Diverse mechanisms, such as sputtering, Fick diffusion, Mullins diffusion, ion-enhanced viscous flow, and ballistics drift, are integrated to characterize the surface evolution. Model simulations and experiments on ultra-smooth SiO 2 substrates with the roughness of several nanometers are performed and compared. Both results demonstrate a consistent trend that surface composition is preferentially re-organized during ion beam sputtering. As ions impinge, surface Si concentration increases from initial 32.5% of un-sputtered surface to about 50% and then falls and eventually stabilizes at 41 ± 1.5%, both in experiments and model simulations. Furthermore, preferential sputtering enhances surface reflectivity (>45%) while scarcely changing surface roughness (

Soft body armour panels have been developed by tuning the structure of 3D woven orthogonal aramid fabrics and reinforcing them with shear thickening fluid (STF). Five 3D woven orthogonal aramid fabric structures were prepared by changing the ratio of stuffer (X direction) to binder (Z direction) yarns and also by changing the relative position of the latter. Two types of ballistic evaluations, namely energy absorption against low velocity (165 ± 10 m s −1 ) bullets and back face signature (BFS) against high velocity (430 ± 10 m s −1 ) bullets were carried out for neat and STF impregnated 3D fabrics and their panels. STF impregnation improved impact energy absorption by 3D woven aramid fabrics. Increasing the ratio of stuffer to binder yarns was found to be beneficial in terms of impact energy absorption and resistance against bullet penetration. STF impregnated 3D fabrics having 4:1 stuffer to binder ratio performed the best in ballistic evaluations. Synergistic effect of 3D woven fabric structure and reinforcement of STF was found to be the key for successful design of soft body armour.

Recent casualties in volcanic eruptions due to trauma from blocks and bombs necessitate more rigorous, ballistic specific risk assessment. Quantitative assessments are limited by a lack of experimental and field data on the vulnerability of buildings to ballistic hazards. An improved, quantitative understanding of building vulnerability to ballistic impacts is required for informing appropriate life safety actions and other risk reduction strategies. We assessed ballistic impacts to buildings from eruptions at Usu Volcano and Mt. Ontake in Japan and compiled available impact data from eruptions elsewhere to identify common damage patterns from ballistic impacts to buildings. We additionally completed a series of cannon experiments which simulate ballistic block impacts to building claddings to investigate their performance over a range of ballistic projectile velocities, masses and energies. Our experiments provide new insights by quantifying (1) the hazard associated with post-impact shrapnel from building and rock fragments; (2) the effect of impact obliquity on damage; and (3) the additional impact resistance buildings possess when claddings are struck in areas directly supported by framing components. This was not well identified in previous work which may have underestimated building vulnerability to ballistic hazards. To improve assessment of building vulnerability to ballistics, we use our experimental and field data to develop quantitative vulnerability models known as fragility functions. Our fragility functions and field studies show that although unreinforced buildings are highly vulnerable to large ballistics (> 20 cm diameter), they can still provide shelter, preventing death during eruptions.

Recent microscale ballistic experiments have revealed that multilayer graphene membranes exhibit exceptionally high ballistic limit velocity and specific penetration energy. A key feature contributing to the exceptional performance of these systems is the cone wave that develops at impact, which propagates radially at a very high speed for ultra-light and stiff graphene membranes, distributing the kinetic energy of the projectile away from the impact zone. Current theories on ballistic impact consider infinitely wide membranes, and atomistic simulations involve very small projectiles and specimen dimensions, and thus cannot ascertain whether microscale ballistics observations are scalable and size-independent. Here, we discover a particular size effect due to the reflection of cone wave that has not been previously observed or considered. We present molecular dynamics simulations showing that there exists a critical membrane size below which the cone wave reflections from the boundaries induce perforation; a phenomenon that is particularly relevant for microballistic testing of graphene membranes. We present an analytical relationship, verified by simulation data, which predicts the critical membrane size simply as a function of the projectile size, membrane thickness and the ratio of the projectile and membrane densities. Our findings provide timely guidance for future microscale experiments and atomistic simulations for accurate characterization of the impact performance of 2D nanomaterials.

This research conducts 300 small-scale ammunition experiments using moderate bullet speeds and a variety of bullet configurations in order to understand the relationship between penetration behavior and bullet shape. To maximize the survivability of soldiers and reduce their vulnerability and ballistics wounds, it is very important to understand the penetration physics of bullets. Inside human bodies, tumbling and traveling trajectories are important factors to consider when analyzing human injuries due to ballistics. Therefore, many kinds of bullets and armor have been proposed to minimize or maximize human damage. In this study, to support the development of bullets, 10 bullets with different head angle shapes and different diameters were manufactured and fired at speeds less than 200 m/s towards transparent gelatin blocks, and the damage mechanisms, i.e., temporary cavities and permanent cavities, were studied by taking penetration images using a high speed camera. It was found that the tumbling and rotations of bullets are influenced by kinetic energies and the shapes of bullets, and several empirical relationships are derived. The results suggest that the shapes and the diameters are crucial factors for ballistics wounds.

The origins of complex projectile weaponry provides insight into cultural and biological changes associated with the origins and spread of modern human populations. Middle Stone Age backed pieces are often thought to be components of such armaments, however our limited understanding of their functional characteristics as projectiles precludes understanding the adaptive problems they may have solved. Despite acknowledgment of raw material differences and intra-assemblage variability, whether variability in backed piece form reflects functional, economic, or stylistic variation has a paucity of empirical support. Here, the functional differences in backed piece form (size and shape) while hafted transversely and obliquely as high-velocity complex projectile armatures are examined. If there are performance tradeoffs simply in how backed pieces are arranged at the end of armaments that can influence effectiveness, then identifying the archaeological arrangement can provide insight into what variables were being prioritized in prehistoric technological systems. How variation in backed piece size, elongation, and hafting arrangement influences complex projectile performance is tested using experimental and actualistic projectile replications with a calibrated crossbow against animal and ballistics gelatin targets. The results of this study show that, within the size and shape variation of silcrete backed pieces examined, tool form plays a relatively limited role in their performance as projectile armatures. However, hafting orientation has very different performance characteristics for complex projectiles shot at ballistics gelatin compared to animal targets. We demonstrate that transversely hafted tools have more lethal internal wounds, but obliquely hafted backed pieces have greater puncture reliability. These functional differences represent different technological design emphasis: transversely hafted tools create large, deep wounds, while obliquely hafted arrows and darts create a puncture more reliably. Although obliquely hafted armaments cause less internal trauma, they are more likely to penetrate the hide of ungulate prey. Variability in MSA hunting tactics may have played a role in the design of weapon systems to optimize these performance tradeoffs. Despite similarities in shape with ethno-historic technologies, based on these results, MSA-sized backed pieces hafted as projectile armatures were unlikely to have been used with small, low-powered bows - but would have been lethal with a high-velocity delivery system.

Materials used in military applications have to withstand multiple threats like ballistics and explosions. Thus, high-strength low alloyed (HSLA) steels are used. The main joining technique for metals is welding. Therefore, analysing the dynamic impact behaviour of high-strength welds is very important to fulfil these demands. Investigation of welds at high strain rates has rarely been conducted in the past. To determine the dynamic impact behaviour of hybrid laser-arc welds, the Split Hopkinson Pressure Bar (SHPB) technique was used. The base material was a quenched and tempered fine-grained armour steel with yield strength of 1100 MPa. First, a full hybrid laser-arc weld was investigated by extracting specimens consisting of weld metal and heat affected base material. The influence of two variables, the cooling time between 800 °C and 500 °C (t 8/5 ) and strength of filler material, on the impact behaviour was studied. The cooling time t 8/5 was varied by preheating to influence the microstructure in the HAZ and to analyse the effect on the hardness and dynamic compressive strength. Subsequent analysis to detail the original investigation was carried out by dilatometer heat treatment of specimens to create homogenous subzones of the weld. These specimens have a homogenous microstructure of HAZ and were tested by SHPB to determine the stress-strain characteristics for the different microstructures of HAZ. The results of the weld specimen showed the effect of preheating and filler material strength on the dynamic compressive behaviour. The analysis of the different microstructures of the HAZ indicated that especially the tempered microstructure caused a reduction in dynamic compressive strength.

In support for the development of a new small-arm ballistic computer based on the NATO Armaments Ballistic Kernel (NABK) for the Canadian snipers, DRDC Valcartier Research Centre was asked to carry out high-fidelity 6 degree-of-freedom (6-DOF) trajectory simulations for a set of relevant vignettes for the snipers, and to compare the direct fire 6-DOF simulation results with those obtained with the 4-DOF NATO Armaments Ballistic Kernel (NABK) adapted to simulate small-arm ammunition trajectories. To conduct this study, DRDC Valcartier Research Centre used BALCO v1.0b. This paper presents (1) the process and the methodology employed to carry out the sniper direct fire solution study, (2) the modeling and the simulation of the sniper projectile, the approach used in calculating the firing solutions, and the results of direct fire simulations for the sniper vignettes, and (3) an analysis of firing solutions obtained with the BALCO engine versus those of NABK. The work presented in this paper serves to validate the use of NABK for the new sniper ballistic computer.

An optimization method is introduced to design the aerodynamic parameters of a dual-spin two-dimensional guided projectile with the canards for trajectory correction. The nose guidance component contains two pairs of canards which can provide lift and despin with the projectile for stability. The optimal design algorithm is developed to decide the profiles both of the steering and spinning canards, and their deflection angles are also simulated to meet the needs of trajectory correction capabilities. Finally, the aerodynamic efficiency of the specific canards is discussed according to the CFD simulations. Results that obtained here can be further applied to the exterior ballistics design.

A single optical fibre sensor is used to measure the dynamics of an impact. The method consists of sewing the optical fibre onto a woven Kevlar layer and placing it between the shoot pack and backing material. The measurement is accomplished by using the friction between the layer and the optical fibre to relate the optical fibre strain to impact deformation. Tests are done using a backing material of Roma Plastilina No.1 clay, and transparent ballistics gel with independent high-speed imaging. A final calculated BFD average error of 7.75% is presented as well as a timing error of 15.5% between the imaged dynamic BFD and the dynamic BFD determined by the FBG. This method is also tested at the U.S. Army Aberdeen Test Center in Maryland with a final calculated error of 7%.

The prehistoric production of composite technologies throughout human evolution was facilitated greatly by the use of adhesives. One such technology was projectile weaponry, which used adhesive to attach a stone point to a wooden shaft. Prehistoric projectile weaponry is often studied via experimental archaeology, which recreates ancient technologies to understand their manufacture and function. Here, we explore whether a modern thermoplastic adhesive can serve as a suitable replacement for two organic adhesives that would have been used by past peoples – pine rosin and hide glue – in modern experimental tests of prehistoric weaponry. We conducted a ballistics experiment and shot groups of stone-tipped arrows, each group hafted with one of the three adhesives, and assessed the haft bond failure rate. The modern thermoplastic adhesive was similar to that of the pine rosin and significantly failed less often than the hide glue. We conclude that in some cases modern thermoplastic adhesive can be substituted for organic-based adhesives in experimental archaeology. Our results also show that hafting bond failure rate was significantly different between the pine rosin and the hide glue, suggesting that prehistoric hunter-gatherers faced costs or benefits in selecting adhesives for hafting.

Energy absorption behavior of flexible armour materials treated with Shear Thickening Fluids (STF) was studied. Five different structures were prepared with varying thread densities of p-aramid yarns, followed by treatment with 60% w/w STF. In untreated condition, plain woven fabrics show highest impact resistance in low velocity impacts, followed by 3/1 twill, 2/2 twill, 5-end satin and 2/2 matt weaves. Ballistic impact mitigation behavior improves with increase in thread density in case of plain woven fabrics. Addition of STF significantly improves both low and high velocity impact behavior of the panels. Low velocity behavior of STF treated fabrics have been published previously [12]. This paper brings together both low and high velocity impact behavior of various geometries of fabrics. It was seen that both primary and secondary yarns are engaged during impact which improves impact mitigation behavior of STF treated fabrics. However, fabrics get jammed at thread densities beyond 32×32 per inch. As was observed earlier in low velocity impact conditions, addition of STF did not enhance performance of fabrics with high thread density in high velocity impact as well.

One of the primary design considerations of earth-orbiting spacecraft is the mitigation of the damage that might occur from an on-orbit MMOD impact. Traditional damage-resistant design consists of a ‘bumper’ that is placed a small distance away from a spacecraft component or from the wall of the element in which it is housed. The performance of such a multi-wall structural element is typically characterized by its ballistic limit equation (BLE), which defines the threshold particle size that results in a failure of the spacecraft element. BLEs are also key components of any micro-meteoroid/orbital debris (MMOD) risk assessment calculations. However, these assessments often call for BLEs to predict impact response for projectiles made of materials not used in the development of those BLEs. The question naturally arises regarding how close are the predictions of such BLEs when used in impact scenarios involving projectiles made of materials not necessarily considered in their development. In an effort to address this issue, a study was performed with the objective of assessing the validity of the NNO BLE for non-aluminum particles. Particle materials considered included steel, copper, and Al 2 O 3 (i.e. particles that are made of materials that are more dense than aluminum). Comparisons are made between actual test results involving these non-aluminum projectiles and the predictions of the NNO BLE. In nearly all cases, the NNO BLE was found not to work very well in the predicting failure / no failure response of these non-aluminum projectiles. A new NNO-type BLE is then developed that can be used to more reliably predict the response of dual-wall systems under the hypervelocity impact of such “heavier” non-aluminum projectiles.

Ballistics is the study of a projectiles motion and can be broken down into four stages: internal, intermediate, external and terminal ballistics. The study of the effects a projectile has on a living tissue is referred to as wound ballistics and falls within terminal ballistics. To understand the effects a projectile has on living tissues the mechanisms of wounding need to be understood. These include the permanent and temporary cavities, energy, yawing, tumbling and fragmenting. Much ballistics research has been conducted including using cadavers, animal models and simulants such as ballistics ordnance gelatine. Further research is being conducted into developing anatomical, 3D, experimental and computational models. However, these models need to accurately represent the human body and its heterogeneous nature which involves understanding the biomechanical properties of the different tissues and organs. Further research is needed to accurately represent the human tissues with simulants and is slowly being conducted.

Sudden hydrothermal eruptions occur in many volcanic settings and may include high-energy explosive phases. Ballistics launched by such events, together with ash plumes and pyroclastic density currents, generate deadly proximal hazards. The violence of hydrothermal eruptions (or explosive power) depends on the energy available within the driving-fluids (gas or liquid), which also influences the explosive mechanisms, volumes, durations, and products of these eruptions. Experimental studies in addition to analytical modeling were used here to elucidate the fragmentation mechanism and aspects of energy balance within hydrothermal eruptions. We present results from a detailed study of recent event that occurred on the 6th of August 2012 at Upper Te Maari within the Tongariro volcanic complex (New Zealand). The eruption was triggered by a landslide from this area, which set off a rapid stepwise decompression of the hydrothermal system. Explosive blasts were directed both westward and eastward of the collapsed area, with a vertical ash plume sourced from an adjacent existing crater. All explosions ejected blocks on ballistic trajectories, hundreds of which impacted New Zealand's most popular hiking trail and a mountain lodge, 1.4 km from the explosion locus. We have employed rocks representative of the eruption source area to perform rapid decompression experiments under controlled laboratory conditions that mimic hydrothermal explosions under controlled laboratory conditions. An experimental apparatus for 34 by 70 mm cylindrical samples was built to reduce the influence of large lithic enclaves (up to 30 mm in diameter) within the rock. The experiments were conducted in a temperature range of 250 degrees C-300 degrees C and applied pressure between 4 MPa and 6.5 MPa, which span the range of expected conditions below the Te Maari crater. Within this range we tested rapid decompression of pre-saturated samples from both liquid-dominated conditions and the vapor-dominated field. Further, we tested dry samples at the same pressure and temperature conditions. Results showed that host rock lithology and state of the interstitial fluid was a major influence on the fragmentation and ejection processes, as well as the energy partitioning. Clasts were ejected with velocities of up to 160 m/s as recorded by high-speed camera. In addition to rare large clasts (analogous to ballistics), a large amount of fine and very fine (

The paper deals with a possibility of the local repairing of damaged composite armours. The proposed repairs can be performed directly in the field, allowing thus to recover the full ballistic protection in a short time. Several solutions (temporary or permanent) were designed and tested both experimentally and using numerical simulations. Overlapping of the damaged area with patch from armour steel after filling the hole with ceramic balls showed to be optimal as a temporary repair. The calculation clearly showed that the depth of penetration of the projectile is reduced in all cases of designed permanent repairs in comparison to original armour configuration. The experiments confirmed supposed enhancing of ballistic resistance, but only some repair techniques met the requirements of multi-hit testing. However, the reason of failure after multi-hit could be clearly explained with the help of used numerical simulations.

The fundamental components of any meteoroid/orbital debris (MOD) risk assessment calculation are environment models, damage response predictor equations, and failure criteria. In the case of a spacecraft operating in low earth orbit, the response predictor equation typically takes the form of a ballistic limit equation (BLE) that defines the threshold particle sizes that cause failure of a spacecraft wall or component. Spacecraft risk assessments often call for BLEs for spacecraft components that do not exist. In such cases, it is a common procedure to use an existing BLE after first equivalencing the actual materials and/or wall thicknesses to the materials that were used in the development of the existing BLE. The question naturally arises regarding how close are the predictions of such an ‘adapted BLE’ to the response characteristics of the actual materials/wall configurations under high speed projectile impacts. This paper presents the results of a study that compared the predictions of a commonly used BLE when adapted to the Soyuz OM wall configuration against those of a new BLE that was developed specifically for that Soyuz wall configuration. It was found that the critical projectile diameters predicted by the new Soyuz OM wall BLE can exceed those predicted by the adapted use of the existing BLE by as much as 50% of the existing BLE values. Thus, using the adapted version of the existing BLE in this particular case would contribute to a more conservative value of assessed risk. If the same trends were to hold true for other spacecraft wall configurations, then it is also possible that using existing BLEs, even after they have been adjusted for differences in materials, etc., may result in predictions of smaller critical diameters (i.e., increased assessed risk) than would using BLEs purposely developed for actual spacecraft configurations of interest.

Previous experimental and theoretical studies suggest that the production of extended defect structures by collision cascades is inhibited in equiatomic NiFe, in comparison to pure Ni. It is also known that the production of such extend defect structures results from the formation of subcascades by high-energy recoils and their subsequent interaction. A detailed analysis of the ballistics of 40 keV cascades in Ni and NiFe is performed to identify the formation of such subcascades and to assess their spatial distribution. It is found that subcascades in Ni and NiFe are created with nearly identical energies and distributed similarly in space. This suggests that the differences in production of extended defect structures is not related to processes taking place in the ballistic phase of the collision cascade. These results can be generalized to other, more chemically complex, concentrated alloys where the elements have similar atomic numbers, such as many high-entropy alloys.

For both ethical and practical reasons accurate tissue simulant materials are essential for ballistic testing applications. A wide variety of different materials have been previously adopted for such roles, ranging from gelatin to ballistics soap. However, while often well characterised quasi-statically, there is typically a paucity of information on the high strain-rate response of such materials in the literature. Here, building on previous studies by the authors on other tissue analogues, equation-of-state data for the elastomeric epithelial/muscular simulant material Perma-Gel ® is presented, along with results from a series of ballistic tests designed to illustrate its impact-related behaviour. Comparison of both hydrodynamic and ballistic behaviour to that of comparable epithelial tissues/analogues (Sylgard ® and porcine muscle tissue) has provided an insight into the applicability of both Perma-Gel ® and, more generally, monolithic simulants for ballistic testing purposes. Of particular note was an apparent link between the high strain-rate compressibility (evidenced in the Hugoniot relationship in the U s -u p plane) and subsequent ballistic response of these materials. Overall, work conducted in this study highlighted the importance of fully characterising tissue analogues – with particular emphasis on the requirement to understand the behaviour of such analogues under impact as part of a system as well as individually.

Sometimes the firearm forensic examiner is required to provide information useful to discriminate between suicide, homicide or accident, or between contradictory reconstructions of the events (like attempted murder versus accidental discharge). In such situations, knowledge of the position and orientation of the firearm at the time of firing can be of fundamental help for the reconstruction of events. To achieve these goals, the analysis of the firing impressions is very important. In this study, the cartridge cases shot with three different revolvers aiming at three different spatial orientations (vertical upwards, horizontal or vertical downwards) were studied. The depth and morphology of the firing pin impression was characterised by optical microscopy and quantified by a surface topography analysis. The orientation of the firearm significantly modified the morphology and depth of the firing pin impression: ammunition fired upwards had the deepest firing pin impression, those fired downwards had the shallowest. Such behaviour was attributed to the different geometry of the firing pin-primer cup interaction and to the different pressure exerted by the primer as the orientation of the weapon changes. Therefore, this work has shown that a suitable protocol of morphological and topographical analysis can be set up to understand if a shot by a revolver was fired holding the weapon upwards, downwards or horizontally.

Why, despite over 30,000 years of ceramic technology and tool diversity documented in the archaeological record – including examples of knapped ceramic scraping tools – was the ceramic arrowhead never invented? Here, we first review the use of ceramic projectile technology and tool use in the archaeological record. Then, via controlled ballistics tests, we investigate whether functional constraints played a role in this global non-invention. By creating “best case” and “worst case” models of ceramic arrowhead, and pitting them both against replica chipped stone counterparts, we show that the former perform significantly worse than the latter in terms of target penetrability and overall durability. By investigating “theoretical” artifacts, we can better understand the evolution of prehistoric technology and why the archaeological record appears the way it does.

Reasonable simulation of the bench blasting has great significance on designing of rock blasting, and the proper consideration of blasting fragmentation size has strong influence on the simulation accuracy. This paper presents a new approach based on the three dimension Distinct Element Code (3DEC) method (Itasca Consulting Group, Inc. 2003) to model the dynamic cracking and casting process of bench blasting with reasonable consideration of blasting fragmentation size. Firstly, an equivalent blasting load consisting of the stress wave pressure and the detonation gas pressure was introduced into the 3DEC model, and it was applied on the outer boundary of blast-induced crushed zone to guarantee the simulation efficiency. Then, the whole numerical model was divided into discrete blocks by several sets of artificial joints to enable the rock to crack, fragment and cast, and at last form a muck-pile, and the artificial joints were assigned with the same mechanical parameters to rock mass itself to avoid the impact of them on stress wave propagation. Different from general discrete schemes which discretize the model with uniform blocks or random balls, the discrete size adopted in this paper gradually increases with distance from the blast source according to the Harries' model (Harries, 1973). At last, the proposed method was examined and verified by simulation of a blasting crater comparing to the field experiment, and then applied to explore the casting process of bench blasting. The simulated muck-pile profile agrees well with the result predicted by the traditional ballistics theory. The simulation also indicates that the casting distance of bench blasting increases with the bench height ( H) , but decreases with the burden distance ( W) , while the height of muck-pile increases with both the W and H . So the muck-pile profile of bench blasting is more sensitive to the W than H after consideration of rock fragmentation size, and the optimization of blasting designs can be significantly enhanced by utilizing the full capabilities of this approach.

Soft-matrix ballistic laminates (such as those composed of fibres of Ultra High Molecular-Weight Polyethylene, e.g. Dyneema® HB26 and Spectra Shield) find extensive use as catching type armour syst ...