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With the technical development of new warhead designs and improvised explosive device protection, irregular casing filled with explosive has been paid more attention recently. In this paper, we studied the fragmentation of a type of D-shaped casing, which is a common asymmetric casing in the field of warhead design. Based on the radiograph technique, static explosive experiments were conducted with D-shaped casings under four different eccentric initiation ratios to explore their fragmentation. A numerical model was then established to simulate the dynamic response of D-shaped casing filled with explosive. The results of numerical simulation were found to agree well with the experimental data. According to the results of numerical simulation and experimental data, the dynamic responses of D-shaped casing were analyzed. The results of the current work pave way for the innovative design of new warhead and for further studying the dynamic response of asymmetric casing. Keywords: D-shaped casing, Eccentric initiation, X-ray radiograph technique, Fragmentation, Numerical simulation

An increasing number of munitions now show less violent responses than detonation in cook off or impact scenarios. The detonation of a warhead typically leads to well reproducible fragmentation effects. Deflagrations and explosions may still rupture the munition casing, but fragmentation is typically limited to just a few large fragments with a relatively low velocity. Fragmentation modeling has evolved significantly with increasingly realistic predictions, even for less violent explosions and deflagrations. Although deflagrating warheads produce only a few fragments, these fragments may reach large distances. Estimates of deflagrating warhead fragment trajectories can be done using platelike fragments. Conventional safety distances are not well suited for this situation. For illustration purposes a simple model of Individual and Group Risk was applied to a case study comparing detonating and deflagrating warheads.

Quest for range enhancement has led to development of Artillery Guns which are capable of generating high pressure levels in the tube to propel the projectiles at increased muzzle velocity. This leads to increased level of launch forces the projectiles are subjected to. Survivability of the Extended Range Full Bore (ERFB) projectile body has been assessed for exploitation with different class of 155mm Artillery Guns. An approach for development of high strength ERFB projectile using existing geometry, raw material and manufacturing set up has been devised, wherein heat treatment process has been altered suitably. Large scale destructive testing of prototypes for evaluating the enhancement in mechanical properties has been carried out. The approach has been validated by conducting dynamic evaluation trials. Static trials for comparing the fragmentation effect of existing and high strength ERFB projectiles have been carried out and the latter have been found to exhibit better performance.

This paper presents theoretical assessment of controlled fragmentation (CF) warhead and its application for (Unmanned Aerial Vehicle) UAV. It is a great challenge to the designer to make small warheads with precision for defeat ofground targets. Attempts have been made to optimize the performance parameters of small warheads to be used in UAVs for defeat of specified ground targets. Warhead performance parameters are characterized by mass distribution and special distribution, velocity of fragments and penetration performance of fragmets against ground targets. Lethality of warhead depends on explosive filling, case materials and controlled fragmentation techniques. Parametric studies are carried out to improve the performance parameters in the best possible manner. The theoretical model shows that the warheads in the weight class of 1kg can defeat simulated targets of 5-mm thick mild steel at a lethal radius of 10m, generating more than 250 numbers of 1 to 2-g compact fragments in beam angles of the range of 100-120.To check out the efficacy and effectiveness, two cylindrical warhead prototypes using controlled fragmentation were fabricated and tested in similar conditions.

The artillery rocket system is the sophisticated type of defence system. One of it is Preformed fragment type warhead. The tungsten fragments-ball, needles, cubes etc. are arranged around the charge mass in such a way that on initiation the fragments are propelled with very high velocity by rupturing the ballistic casing. These ballistic casing can be made of different materials according to the aerodynamic loading, structural loads etc. Generally used casing materials are FRP, steel, aluminium. Due to difference in the material properties the fragment velocity, energies and the pressure generated are affected. To study these effect static and dynamic trails prove costly and time consuming. So an alternative method of simulation of warhead with different ballistic casing is presented. During simulation the multilayer fragments are replaced by single layer having equivalent mass as it is difficult to model 20000 no of fragments. Hence the results obtained are in good agreement with the available data.

Simulation of Military ground vehicles subjected to buried landmines, and Improvised Explosive Devices (IED) has been carried out by many researchers, and military establishments to understand the effects in detail. But the ability to predict the effects of fragmenting IED’s on military ground vehicles is little known in simulation community. Hydrocode simulation such as Eulerian simulation and Arbitrary Lagrange in Eulerian (ALE) simulation coupled to vehicle structure is widely used methodology to characterize buried detonating IED. But for fragmenting IED’s capturing the fragmentation and fragmenting elements are necessary and ALE may not be able to capture it. There are several statistical and empirical formulations that are available to approximately estimate the number of fragments, but does not provide sufficient information about the velocities of the fragments. In this proposed study, a 152mm High Explosive (HE) OF-540 fragmenting projectile was modelled in detail per geometry and buried 100 mm deep inside the soil. This fragmenting projectile was coupled to U.S. Army’s Ground Vehicle System Center (GVSC) developed generic hull (GH) structure to understand the impact effects of fragmenting fragments. Three different analysis were carried out Projectile buried in soil with adaptive SPH projectile casing, Projectile buried in soil coupled to GH structure with projectile casing as ALE and projectile casing as adaptive SPH methods. Results from all the three analysis were thoroughly analyzed and findings from these analysis is presented in this paper. Solid element formulation is well suited for shock waves, crack propagation and fragmentation problems was used in modeling all the structural and projectile components using commercially available structural code LS-DYNA-3D.

Passive armours are the conventional methods used for protection of AFV against high velocity or high energy projectile threats. But due to improvised penetration capabilities of modern projectiles, these passive armours do not meet the expected safety standards. Hence, alternate counter measure mechanisms need to be developed to enhance the protection level. One of the kill mechanism is deflecting the incoming projectile using blast wave. Directed or controlled blast wave is generated, which creates blast wave in close ranges of the projectile. This blast wave intercepts/deflects the path of the projectile. In this paper, finite element based explicit dynamic analysis is done to analyze the effect of two different kill mechanisms of countermeasure against two different projectile threats. Blast wave effect against long rod penetrator and fragmentation effect against high energy (HE) projectiles are considered in the present paper.

Determination of Surface Danger Zones (SDZs) is a safety related issue of paramount importance which must be addressed. Several technical factors are involved in SDZs determination for a specific weapon and ammunition system: range of fire, dispersion, ricochet and fragmentation. This work is focused on the ricochet and fragmentation of 120 mm typical training round tank ammunition during high velocity impact. The modeling is based on numerical simulation for analyzing the large deformation dynamic response of the round structure during impact. The main aim of the numerical analysis was to examine the various impact parameters of the ricochet i.e. the critical angle for penetration or fragmentation and to understand the effect of the impacted surface properties on the ricochet behavior. The numerical model presented was calibrated and compered to ricochet firing test that included 120 mm tank training round fired against hard armored steel, and soft soil targets.

The fragmentation of rings and shells is a topic of enduring interest both because of the interesting dynamic conditions under which it takes places and the practical importance of fragmentation to various military and industrial applications. Fragmentation is a complex process in which potential fracture sites interact with one another in a deforming body to form a population of fragments. The details of this process are important, and realistic models need to capture the essential features of this process in order to make accurate predictions.

Designers who design structures to mitigate against blast loadings (Remennikov 2007) have another duty and that is to design for the effects of fragmentation not only caused from bulk explosives, but also impact from projectiles. Impact causes damage to a structure and inevitably results in debris from penetration and perforation (breach) of the structural elements. This debris is in fact the result of the damage outcome to a structure either from the blast loading or projectile impact. Fragmentation (Bangash 2006) is the end result of the blast waves impacting the structural elements resulting in scabbing and spall both of which manifest themselves in the production of fragmentation. This fragmentation is propelled outwards at velocity causing supplementary damage to the structure, adjoining structures and individuals caught near the fragmentation. Those designing for fragmentation must consider many parameters from the geometry of the impacted structural element, to the velocity of the fragments, the weight of the fragments and the range of the fragments. As has been said the fragments cause damage and the designers overall duty is to design to mitigate against damage and death or injury to individuals. The pool of worldwide knowledge on this topic is growing exponentially particularly as the need arises with weapons of high velocity and sophisticated projectiles of extreme lethality and range.

The purpose of this article is to develop a mathematical model describing the process of forming the initial kinematic parameters of the fragmentation field. Efforts to increase the effectiveness of ammunitions have been explored, namely increasing the area of damage, by using system for continuous initiation of the explosive substance. The results obtained can be used in the development of ammunitions designed for countering terrorist and other threats as components of critical infrastructure protection systems.

The mid-1960s saw the beginnings of the construction of a Palestinian political field after it collapsed in 1948, when, with the British government’s support of the Zionist movement, which succeeded in establishing the state of Israel, the Palestinian national movement was crushed. This article focuses mainly on the Palestinian political field as it developed in the 1960s and 1970s, the beginnings of its fragmentation in the 1990s, and its almost complete collapse in the first decade of this century. It was developed on a structure characterized by the dominance of a center where the political leadership functioned. The center, however, was established outside historic Palestine. This paper examines the components and dynamics of the relationship between the center and the peripheries, and the causes of the decline of this center and its eventual disappearance, leaving the constituents of the Palestinian people under local political leadership following the collapse of the national representation institutions, that is, the political, organizational, military, cultural institutions and sectorial organizations (women, workers, students, etc.) that made up the PLO and its frameworks. The paper suggests that the decline of the political field as a national field does not mean the disintegration of the cultural field. There are, in fact, indications that the cultural field has a new vitality that deserves much more attention than it is currently assigned.

The paper presents the results of forensic analysis of improvised dummy grenades modeled after the airsoft hand grenade RGS-4 for use in tactical simulation wargames like «Airsoft». Initial testing by experts affiliated with a different system of forensic science institutes led to the conclusion that these devices are capable of producing explosions and causing fragmentation damage. The purpose of this study conducted by two forensic science centers of the Ministry of Justice of the Russian Federation was to correct the classification of improvised devices as explosive devices. Results indicate that these devices that consist of a cardboard (paper) or rubber-like casing filled with dried peas, with a «Korsar-4» firecracker in the middle, have the formal characteristics of an explosive device but cannot be regarded as such (as per Article 222 of the Criminal Code of the Russian Federation), since they are in effect typical imitation pyrotechnic devices similar to dummy hand grenades RGS-4 and display no significant damaging properties.

While over the past century fairly extensive work has been carried out on explosively-driven metallic envelope fragmentation, as the development of explosive materials and warhead configurations continued, the issue under consideration is still topical. The current paper aims to investigate the fragmentation characteristics of explosively-driven steel cylinders when double layer envelopes are used. Mott�s approach was modified in order to account for such particular configuration (layered envelope). Several tests in a simplified type procedure were performed aiming to confirm the theoretical approach.

New advanced numerical computer model enabling accurate simulation of fragmentation parameters of large Length over Diameter (L/D) explosively driven metal shells has been developed and validated. The newly developed large L/D multi-region model links three-dimensional axisymmetric high strain high strain-rate hydrocode analyses with the conventional set of Picatinny Arsenal FRAGmentation (PAFRAG) simulation routines. The standard PAFRAG modeling technique is based on the Mott's theory of break-up of idealized cylindrical “ring-bombs”, in which the length of the average fragment is a function of the radius and velocity of the shell at the moment of break-up, and the mechanical properties of the metal. In the newly developed multi-region model, each of the shell region, the break-up is assumed to occur instantaneously, whereas the entire shell is modeled to fragment at multiple times, according to the number of the regions considered. According to PAFRAG methodology, the required input for both the natural and the controlled fragmentation models including the geometry and the velocity of the shell at moment of break-up had been provided from the hydrocode analyses and validated with available experimental data. The newly developed large L/D multi-region PAFRAG model has been shown to accurately reproduce available experimental fragmentation data.

This paper presents an innovative explosive welding technology, namely Universal Substitutive Explosive Welding technique, which was recently developed by Australian Defence Science and Technology Group to improve the survivability and mobility of military vehicles. The new technique is superior to the existing industrial explosive welding ones in terms of integrity, quality and stability. It is able to significantly upgrade the hardness upper limit of target material and ensure the perfect welding bond between the flyer (soft) and target (hard) panels without size limitation of target panel. Experimental results show that using the new technique raised the ballistic velocity limit (V50) of the explosively welded panel by up to 20% and reduced the bulge depth (related to dynamic plasticity) significantly without any rupture or fragmentation issues. Charpy impact test on the sample fabricated by the new technique showed strong recovery effects with time with no transition temperature. Keywords: Explosive welding, Armour materials, Ballistic velocity limit, Bulge depth, Charpy impact test

Blast-induced fragmentation has a significant influence on the operational efficiency of open pit mines, especially on loading and crushing, the two immediate tasks after blasting. This study presents an empirical method to determine the target fragmentation for efficient loading and crushing at the Aitik mine in Sweden. In the study, the loading efficiency of rope shovels was correlated to the energy consumption and throughput of a gyratory crusher. Two photographic techniques were utilized to assess the feed fragmentation, considering the lithological origin of the ore as an indicator of hardness. The results indicate ore hardness is most influential in mid-range fragmentation, with a marginal effect in coarser fragmentations. The influence of fragmentation is more pronounced in the coarse region, with a sudden reduction in efficiency for P80values coarser than 800 mm. The results suggest tailoring the fragmentation to a P80 of 600-800 mm could lead to higher operational efficiency at Aitik.

Engineering blasting is considered the most economical means of rock fragmentation. The explosive energy utilization is limited to 7% to 22% for fracturing and fragmentation though. The rest of energy components manifests itself into deleterious effects of engineering blasting, namely – noise, air overpressure, ground vibrations, etc. It has been established that proper application of air-decking and stemming plugs may enhance explosive energy utilization to a good extent. This paper substantiates this fact wherein distinct explosive energy utilization enhancement has been achieved with the combination of air-decking and stemming plug. The stemming plug used has acronym as, SPARSH (Stemming Plug Augmenting Resistance to Stemming in Holes) and it is perhaps the only available device which can effectively be used with air-decking. Further, SPARSH doesn’t restrict the type of stemming material and stemming length. This is a significant advancement in the engineering blasting.

How does a shell explode into a series of fragments upon impact? The well accepted explanation is Mott's theory, which considers the fragmentation of shells as a random process controlled by defects. However, Mott's theory is inadequate due to its assumption of energy conversion, and it is incapable of explaining the lack of change in saturation fragment length with the increase in expansion velocity. In this paper, we present a theory to explain the physical mechanism for fragmentation of shells and propose a highly efficient model for predicting the number of necks after fragmentation. We recognize that the fragmentation problem in shells is analogous to the cracking behavior of tree bark, and closed form solutions is obtained to describe the relationship between the expansion velocity and the number of necks with consideration of the strain rate dependent strength of the shell material. The theoretical results show excellent correlation with the experimental results., 5 pages, 4 figures

The article deals with the main issues of implementation of the main trends in the development of artillery weapons. Its increase in the efficiency of the use of artillery shell fragmentation shells by introducing the latest technological developments in the means of correction of the trajectory. The situation that occurred during the Military Operation of the Joint Forces in the Donetsk and Luhansk Oblasts of Ukraine in 2014 required the use of not only light weapons but also more powerful weapons, namely artillery weapons, against illegal armed groups with high spectacular capabilities, maneuverability, clear control system. The experience of fighting in the area of modern military conflicts (the civil war in Syria) confirms the urgency of using high-precision weapons, namely high-precision artillery shells, since major hostilities occur in settlements.

Oil shale is a kind of high-combustion heat mineral; in the process of exploitation, storage, and utilization, oil shale dust has the risk of explosion. The explosion characteristics and flame propagation behavior of oil shale dust are worth studying. The difference between the multiple explosion behaviors of oil shale dust was investigated with the use of a 20 L explosive spherical tank and a dust MIE experimental device. The explosion characteristics and microstructure changes of the explosive products in multiple explosions were examined. The experimental results show that the maximum explosion pressure (Pmax) dropped, and simultaneously, the minimum ignition energy (MIE), the explosion time (t), and the maximum rate of pressure rise (dp/dtmax) increased as the explosions continued. Furthermore, the oil shale continued exploding until the third explosion. Some original oil shale dust (OOSD) and explosive residues were analyzed using a scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) spectrometer. The SEM images of the explosive residues indicate a high fragmentation degree and well-developed pore structure during the entire multiexplosion process. Oxygen-containing functional groups, the aliphatic C-H bond, and the aromatic C-H bond in oil shale dust all participated in the oil shale dust explosion process.

The destruction of thick-walled cylindrical shells under explosive loading is a typical example of a problem that cannot be solved without taking into account the heterogeneity of the material’s internal structure. A probabilistic approach to numerical simulation of dynamic fracture is described. Fragmentation spectrum of shells fracture under explosive loading (flat 2D modeling) is compared for different distributions of the strength properties. Using numerical simulation results, it is shown that increasing of strength properties dispersion leads to an increase in the spectrum part of medium and large fragments. It is shown that the fragmentation spectrum is determined mainly by dispersion of the distribution law, but not its shape.

The drilling process is one of the most common processes on many manufacturing areas. It is used for high-quality hole drilling of Aluminium 6061 alloy. In this experimental study precise holes were drilled, using drills with high pressure internal cooling (50 Bar). The influence of the process parameters on holes quality is analysed. Another aspect studied is chip shape and evacuation.

The damage pattern of rear wall/witness plate could express the fragmentation features of projectile relatively, in the ground-based tests of Whipple shield and its improved structure. In this paper, the damages of rear wall for 20 Whipple shield tests are statistically analyzed, and the linkage between the damages with impact conditions (impact velocity and plate-thickness-to-sphere-diameter ratio) are obtained. The damage pattern of rear wall, or the fragmentation pattern of sphere is defined as Intact, Ruptured and Smashed. The perforation hole on rear wall is described quantitatively. The fragmentation patterns under different impact conditions are analyzed based on the propagation and evolution of shock waves. A series of SPH simulations prove and extend the analytical and experimental works, and clearly reveal the normalized relationship between fragmentation pattern and impact condition.

The aim of this work is to simulate the fragmentation of bullets impacted through granular media, in this case, sand. In order to validate the simulation, a group of experiments were conducted with the sand contained in two different box prototypes. The walls of the first box were constructed with fiberglass and the second with plywood. The prototypes were subjected to the impact force of bullets fired 15 m away from the box. After the shots, X-ray photographs were taken to observe the penetration depth. Transient numerical analyses were conducted to simulate these physical phenomena by using the smooth particle hydrodynamics (SPH) module of ANSYS&reg, 2019 AUTODYN software. Advantageously, this module considers the granular media as a group of uniform particles capable of transferring kinetic energy during the elastic collision component of an impact. The experimental results demonstrated a reduction in the maximum bullet kinetic energy of 2750 J to 100 J in 0.8 ms. The numerical results compared with the X-ray photographs showed similar results demonstrating the capability of sand to dissipate kinetic energy and the fragmentation of the bullet caused at the moment of impact.

In medico-legal literature, only a small number of publications deal with lethal injuries caused by shots with modified guns. This might lead to the conclusion that such cases are extremely rare. However, there are cases again and yet again. During the investigation process, the modified gun is of particular importance since it can show an unusual ballistic behaviour. The present paper reports on a suicide of a 60-year-old man, committed with a modified revolver and a lead bullet. The man had a single gunshot wound with entrance at the right temporal bone. Autopsy revealed that the bullet had fragmented into two major parts. The smaller one stood outside the cranial cavity and pushed its way alongside between the cranial bone and scalp to its end position in the left temporal area. The bigger part entered the cranial cavity and ended in the left parietal lobe. In shots on ballistic soap and on a head-model, the ballistics of the weapon and lead bullet were characterized. The angle necessary for bullet fragmentation was determined by shots on ballistic soap and turned out to be 55°-60° at a velocity of around 200 m/s. This knowledge was transferred to contact shots on a head-model consisting of a layered polyurethane sphere filled with 10 % ballistic gelatine and covered with a skin-like cap almost all around. The resulting injury pattern corresponded to the one of the suicide person. The bigger bullet part entered the skull while the smaller part pushed its way alongside between skin and skull causing an outer contour shot. Furthermore, the revolver was documented firing off two bullets by one trigger pull-a phenomenon of importance for forensic casework the authors have not found reported in forensic literature.

The tuneable effects concept is aimed at achieving selectable blast and fragmentation output, to enable one charge to be used in different scenarios requiring different levels of blast and fragmentation lethality. It is a concept QinetiQ has been developing for an energetic fill consisting of three principal components arranged in co-axial layers, two explosive layers separated by a mitigating but reactive layer. The concept was originally designed to operate in two modes, a low output mode which only detonates the central core of high explosive and a high output mode which detonated both the central core and outer layer of the explosive. Two charge case designs where manufactured and tested; one of these designs showed a reduction in blast and fragment velocities of ~33% and ~20%, respectively, in the low output mode.

One of the reasons causing vibration for gear hob toothing is the shock at the tool’s entry, which is generated by the great length of the cutting edge entering the metal at the same time. This paper proposes a fragmentation of the cutting edge so that its length is much smaller. Moreover, the cutting scheme is also changed, so that the entire tooth line of the piece is made with four consecutive teeth of the tool. Therefore, the impact force input generating shock and vibration is significantly reduced.

Ballistic tests with plate and stiffened targets impacted by cylindrical and blade-like projectiles were conducted using compressed gas gun to investigate the perforation-resistance performance of aero-engine fan casing during a blade-out event. It was observed that for the plate target impacted by the blade-like projectile, fragmentation on the projectile nose occurred and the targets were failed by petaling; but for the other combinations, the main failure mode of the targets was plugging and the projectiles were intact except in cases when the blade-like projectile hit the stiffeners. Due to the distinct failure mode, ballistic limit for the plate target impacted by the blade-like projectile was much higher. To analyze the perforation resistance of the target, the energy absorption modes were classified and described with analytical models. A new dishing energy calculating method was proposed for a plate normally impacted by an arbitrary cross-section projectile. The energy absorbed by each mode and the ballistic limits for the plate target were calculated using these analytical models. It was found that fragmentation of the projectile led to a larger amount of dishing energy. The formation conditions of the fragmentation on projectile nose were theoretically analyzed, and the influencing factors for the fragmentation such as the critical thickness of the target and the critical impact velocity of the projectile were derived with established formulas. The theoretical analysis agreed well with the test results. It is argued that if the target is thicker than the critical thickness and the initial velocity of the projectile is larger than the critical impact velocity, fragmentation on projectile nose will occur, failure mode of the target will change to petaling, and the perforation resistance of the target will be significantly enhanced.

Natural fragmentation of warheads that detonates causes the casing of the warhead to split into various sized fragments through shear or radial fractures depending on the toughness, density, and grain size of the material. The best known formula for the prediction of the size distribution is the Mott formulae, which is further examined by Grady and Kipp by investigating more carefully the statistical most random way of portioning a given area into a number of entities. We examine the fragmentation behavior of radially expanding steel rings cut from a 25 mm warhead by using an in house smooth particle hydrodynamic (SPH) simulation code called REGULUS. Experimental results were compared with numerical results applying varying particle size and stochastic fracture strain. The numerically obtained number of fragments was consistent with experimental results. Increasing expansion velocity of the rings increases the number of fragments. Statistical variation of the material parameters influences the fragment characteristics, especially for low expansion velocities. A least square regression fit to the cumulative number of fragments by applying a generalized Mott distribution shows that the shape parameter is around 4 for the rings, which is in contrast to the Mott distribution with a shape parameter of ½. For initially polar distributed particles, we see signs of a bimodal cumulative fragment distribution. Adding statistical variation in material parameters of the fracture model causes the velocity numerical solutions to become less sensitive to changes in resolution for Cartesian distributed particles.

The composition, structure, manufacturing process and properties of Metallic reactive materials are introduced. The typical ternary mixture of Ni-Al-W have high density of 7.37g/cm3 and static tensile strength of 228MPa, which make the reactive fragments gain high penetration capability to perforate the target&s skin and can survive under explosive. The Ni-Al-W fragments undergo intermetallic reaction and oxidation reaction upon impacting. The energy release characteristics of Ni-Al-W reactive material were analysed. The chemical energy and pressure generated by reaction of the reactive material have a linear relationship with the impact velocity. A warhead prototype of Ni-Al-W fragment warhead was designed and the warhead explosion testing was carried out. The results show that the Ni-Al-W fragments are capable of withstanding to explosive loading with acquiring initial velocity of 2256m/s. The Ni-Al-W fragments also have advantage of perforation in area against the bi-layered space plates. The metallic reactive fragment warhead can increase the lethality of fragmentation warheads against aircrafts and phased array antenna, which increasingly get mature and have a wide application prospect.

The fragmentation of a shell filled with explosive is quite valuable for evaluating the killing ability of improvised explosive device. A typical explosive device with Q235 steel shell and TNT explosive is chosen to study the fragmentation of thin-walled structure. With sand recovery method, experiments are conducted to get fragments with the mass above 0.1g. G-S formula shows a better agreement with experimental results when predicting average fragment mass than Mott formula. Further researches show that shell thickness and length-diameter aspect ratio have great effect on the fragmentation of shell. Average fragment mass increases exponentially and total fragment number decreases exponentially when shell thickness increases, while average fragment mass remains almost unchanged and fragment number grows linearly when length-diameter aspect ratio increases. These results are very helpful for whenever academic study or real application.

A High-velocity Impact-ignition Testing System (HITS) was developed to study the dynamic response of intermetallic projectiles penetrating through two aluminum plates at impact velocities up to 1300 m/s. The intermetallic projectiles are contained in a 0.410 caliber shot gun shell and launched from a propellant driven gun into a catch chamber equipped with view ports and imaging diagnostics. Penetration, impact, and reaction are monitored using high-speed cameras that provide macroscopic and localized perspectives of projectile and target interaction. Several key results include the following. The first-plate penetration of the projectile follows well established ballistic curve fits. Subsequent plate penetration shows significant deviations attributed to projectile damage resulting from the first plate impact. The damage imparted to the projectile transitions from significant plastic deformation to severe fragmentation as impact velocity increases. Penetration of the aluminum target plate is significantly affected by the fragmentation field and show a 45% increase in rupture size at the highest impact velocity case. Combustion within the fragmented projectile is observed starting at 850 m/s. These results show the transition in dynamic interaction between multiple target plates at increasing projectile impact velocity.

For studying response characteristics resulting from fragmentation warhead fragment impact on shielded H6 explosive. H6 explosive has been shielded with Q235 steel, what was impacted for cuboid tungsten fragments at the velocity range of 2000 m/s~2200 m/s launching from 25 mm ballistic gun, with different quality and length-thick ratio of square, The process of impact response was observed by high-speed photography. The maximum diameter and duration of the fireball as well as destruction of shielded H6 explosive were recorded, then corresponding features of shielded H6 explosive were analyzed accordingly. Furthermore, the mechanism of H6 explosive responses was analyzed based on the theory of explosive impact initiation. Results show that it mainly includes combustion, deflagration and detonation for response features of targets, and it has highest probability for deflagration. Adiabatic shear effect was regarded as the functional mechanism, which could produce different response characteristics. Deflagration reactions could be sparked in which of the situations the quality of fragments was no less than 10 g. what's more, the most violent deflagration reactions could be sparked under the certain condition that the length-thick ratio of fragment was about 1.6.

After nearly four years of civil war, Libya continues to be described as an ‘ungoverned space’ where the collapse of state institutions reignited tribal, political, religious and ideological tensions. These accounts, however, obscure Libya’s complex subnational governance, and the role of non-state armed groups in shaping the emerging political orders. By contrast, we contend that distinct subnational political orders have emerged in Libya since 2014 in which actors engage in state-making practices driven by local interests. Using empirical evidence to explore the activity of non-state armed groups during the Libyan civil conflict, we highlight that the local conflict environments in eastern, western and southern Libya provide specific incentives that shape the process of armed group splintering and patterns of violence. The findings demonstrate that claims to authority and notions of statehood extend far beyond the state whereby governance relations are negotiated between state and non-state actors. Conflict patterns, (in)stability and the prevailing political order are therefore conditional on the nature of the dominant actor, their strategies and modes of violence within their areas of influence. Through this analysis, the paper provides a more granular understanding of the local political dynamics that drive violence in Libya and civil wars more generally.

The results of the process of explosive throwing of a set of fragmentary disks with the charge of an explosive are given in the work. This set consists of two disks of natural crushing of different thicknesses of a fixed total mass. The research was carried out using the computer simulation of shock-wave processes in the continuous formulation using the ANSYS/LS-DYNA program. The influence of the order of the installation of discs of different thickness on the value of the angle of fragmentation of the fractional mass and the axial velocity of its motion is established.

To study the key technical issues involved in the field of reconstruction of improvised explosive devices (IEDs), the formation mechanism of natural fragmentation under blast loading was investigated using the finite element code AUTODYN 3D with Mott’s stochastic failure model. The analysis of structural response, critical failure condition, as well as dispersion characteristics including initial angle and velocity of fragments were also carried out. Meanwhile, the effects of charge mass and structure were discussed. The results of the mass and number of fragments, as well as the radius of flight can be used to reconstruct the explosion scene of IEDs.

This study analyses the use of composite metal foam (CMF) to mitigate the damage caused by blast and fragmentation threats. A major threat to military and civilians in war-torn regions is the increasing use of improvised explosive devices (IED’s). These explosives can cause damage to equipment and injure solders through blast wave propagation and fragment penetration. In order to minimize such injuries and damages, advanced materials with high-energy absorption capabilities are needed. In this study, steel composite metal foam panels with extra-ordinary energy absorption capabilities have been tested in various thicknesses to defeat 23 x 152 mm High Explosive Incendiary rounds (HEI). The incendiary round impacts an initial target (a thin aluminum plate) creating a blast wave and fragment particles of various sizes (small, medium and large) that will then impact the CMF panels positioned approximately 45 centimeters away from the target aluminum panel. In addition to the experimental approaches, the CMF system is modeled using IMPETUS Afea Solver for validation. Both the experimental and modeling results indicated that composite metal foam panels were able to defeat different sizes of fragments resulted from a 23 x 152 mm HEI round, with fragment speeds reaching up to 1500 m/s.

The fracture pattern of shells with a filler at collision with high-speed projectiles is analyzed. The special features of the projectile and barrier fragmentation and formation of debris fields, and the impact of the shock wave on the filler are revealed.

The sphere impacting on the thin wall is simulated with node-separation finite element method, and investigations of the projectile fragmentation initiation threshold are processed based on the numerical results. The bumper-thickness-to-projectile-diameter ratio ( t/ D) is found to be the main determinant of the velocity threshold. The simulation cases contain the t/ D ranging from 0.008 to 0.424 and impact velocity ranging from 2 km/s to 7 km/s. The numerical results are in good agreement with the tests in sphere fragmentation initiation threshold, inner spall of the sphere, debris cloud pattern. The simulations reproduce the fragmentation initiation threshold curve that is obtained by the tests. That shows the feasibility of node-separation finite element method for hypervelocity impact simulation. The shock wave analyses show that the propagation/reflection process of shock wave in the thin wall cases is very different from that in thick wall cases. That inherently results in the different variations of the threshold in the low and high intervals of t/ D. The extreme thin plate case shows that when t/ D is further reduced, a thick layer of debris cloud would form at the rear of the plate. Compared to the projectile residual, the debris cloud from the plate would induce wider destruction in the inner structure.

The aim of the paper is to presents one of the possible approaches to the numerical analysis of the behaviour of directed fragmentation war heads. These kinds of warheads consists of: metallic or composite cover, explosive material and a driven and fragmentation liner. The explosives are initiated by a booster causes driving the liner in a few milliseconds up to about 900 m/s. The liner fragments into many parts during this intensive and dynamic load. The fragments move in a cone which dimensions depend on the warheads shape and mechanical parameters of others warheads parts. All of the warheads elements are selected to meet the assumed parameters. The fragments velocity, their mass or geometric dimensions and cone angle are the most important parameters of the warheads fragments. Such a warhead, in the initial phase of the liner driving can be numerically modelled in the field of the continuum damage mechanics. Such a description is presented in other papers. This approach in a further phase of driving cause the increases of inaccuracies. Therefore, this paper proposes the use of ALE and FSI approach to describe the behaviour of the fragmentation warheads. A three-dimensional numerical model of the directed fragmentation warheads was made in the MSC Patran, and the dynamic phenomena analysis used a nonlinear finite element method implemented in the LS-Dyna program.