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Sabot asymmetric discard after the projectile being launched from the muzzle at various angles of attack and 4Ma is investigated. This is implemented by the coupling computational fluid dynamics (CFD) and six degrees-of-freedom exterior ballistic code through the unstructured dynamic mesh and user defined function. The flow field characteristics during sabot discard process and the trajectory parameters of all three sabots have been obtained. In addition, the aerodynamic coefficients of the projectile are also obtained. The numerical results show that the asymmetric discard of sabot is more obvious along with the increasing angle of attack. Moreover, the aerodynamic forces of projectile have a larger change and the pressure distribution of its surface is more asymmetric and complex. This means the aerodynamic interference at a non-zero angle of attack contributes more significantly to shooting dispersion and flight stability than that at zero angle of attack and the influence increases as the angle of attack increases.

En este trabajo se estudian las protecciones balísticas ligeras con las que se podrían hacer un prototipo de casco capaz de detener balas de rifle de forma segura. La protección balística de la cabeza a través de los cascos presenta un nivel inferior con respecto a la protección disponible para el resto del cuerpo, a pesar de la gran importancia. Esto es debido a las importantes limitaciones de peso que puede soportar, así como a la fragilidad del cráneo y cerebro, siendo una barrera infranqueable que ha causado que los cascos usados por la policía y los ejércitos de todo el mundo solo sean capaces a de detener de manera segura balas de pistola. Las balas de rifles tienen mucha más capacidad de penetración y este tipo de amenaza es cada día más común debido a los cambios que se producen en los diversos teatros de operaciones., In this work, the light weight ballistic protections are studied in order to mature a prototype helmet capable of stopping rifle bullets. The ballistic protection of the head through the helmets is lower than the protection available for the rest of the body, despite the great importance for the survival of the user. This is due to the significant weight limitations the head and neck can withstand, as well as the fragility of the skull and brain. This has been an impassable barrier that has caused the helmets worn by police and armies around the world to only be able to safely stop pistol bullets. Rifle bullets are much more dangerous; and this type of threat is becoming more common due to the changes taking place in the various theatres of operations. This makes a thorough study of the problem necessary to improve the safety and security of users.

The PELE ammunition is characterized by a low-density filling material surrounded by a high-density brittle jacket material. An analytical model describing the fragmentation of this ammunition behind a target plate is presented. This model assumes uniaxial strain in the filling and uses the Ranking–Hugoniot relations to calculate the material state. In addition, shock and rarefaction wave interactions at the target free surface and the filling/target interface are accounted for, as well as the radial rarefaction originating from the jacket outer surface. This allows the calculation of the pressure evolution in the filling and the radial acceleration of the jacket at any axial position along the projectile. This model aims at improving previously published analytical models where the acoustic wave approximation was used and the wave interactions were neglected. Experimental results (Paulus and Schirm, 2006) are used to validate the analytical model for different target materials (aluminum and steel), target thicknesses (3 mm and 8 mm), filling materials (polyethylene and aluminum) and impact velocities (900 m/s to 3000 m/s). A qualitative comparison based on X-ray photographs reveals similar features between the model and the experiments, such as smaller and lighter fragments with a greater radial velocity at the front of the projectile compared to the fragment characteristics at the back of the projectile. A quantitative comparison based on the maximum radial velocity of the fragments shows on average a 20% difference between the analytical and experimental results for all impact conditions considered. Despite this difference, the analytical trend follows more closely the experimental one compared to the acoustic approximation especially at high impact velocities. In addition, the acoustic approximation fails to reproduce the jacket fragmentation pattern since the fragmentation length of the jacket is significantly under-predicted. A numerical simulation is also presented using the ANSYS Autodyn 14.0 software. The results show that the numerical and analytical pressure evolution in the filling and the radial velocity of the jacket are in very good agreement, verifying the uniaxial strain assumption. This agreement (together with the experimental agreement) thus suggests that the Rankine–Hugoniot relations, the wave interactions and the radial rarefaction wave must all be included in the model to adequately describe the fragmentation of the PELE ammunition behind a thin target plate.

Composite laminates made of glass/epoxy with and without nano fillers were subjected to projectile impact. The laminates of different thicknesses were prepared by hand lay-up and compression molding processes. Laminates were made from glass woven roving mats of 610 gsm, epoxy resin and nano clay of 1-5 wt.% of matrix. A piston type gas gun setup was used to impact a spherical nose projectile of diameter 9.5 mm and mass of 7.6 g, on the nanocomposite laminates at impact velocities in the range of their ballistic limit and above. The energy absorbed during penetration and ballistic limit of the nanocomposite laminates were studied both experimentally and analytically. The analytical model also predicts the energy absorbed in various failure modes due to tensile failure of primary fibers, deformation of secondary fibers, delamination and matrix crack. Mechanical properties like tensile modulus, stress-strain function, shear modulus, and strain energy release rate were used as input to the analytical model. Laminates of three, five and eight layers have been considered for the analysis. The effect of clay dispersion in the matrix for different failure modes is discussed. Ballistic limit obtained from the model is validated with experimental results and good agreement is found. � 2014 Elsevier Ltd. All rights reserved.

The PELE ammunition is characterized by a low-density filling material surrounded by a high-density brittle jacket material. An analytical model describing the fragmentation of this ammunition behind a target plate is presented. This model assumes uniaxial strain in the filling and uses the RankingeHugoniot relations to calculate the material state. In addition, shock and rarefaction wave interactions at the target free surface and the filling/target interface are accounted for, as well as the radial rarefaction originating from the jacket outer surface. This allows the calculation of the pressure evolution in the filling and the radial acceleration of the jacket at any axial position along the projectile. This model aims at improving previously published analytical models where the acoustic wave approximation was used and the wave interactions were neglected. Experimental results (Paulus and Schirm, 2006) are used to validate the analytical model for different target materials (aluminum and steel), target thicknesses (3 mm and 8 mm), filling materials (polyethylene and aluminum) and impact velocities (900 m/s to 3000 m/s). A qualitative comparison based on X-ray photographs reveals similar features between the model and the experiments, such as smaller and lighter fragments with a greater radial velocity at the front of the projectile compared to the fragment characteristics at the back of the projectile. A quantitative comparison based on the maximum radial velocity of the fragments shows on average a 20% difference between the analytical and experimental results for all impact conditions considered. Despite this difference, the analytical trend follows more closely the experimental one compared to the acoustic approximation especially at high impact velocities. In addition, the acoustic approximation fails to reproduce the jacket fragmentation pattern since the fragmentation length of the jacket is significantly under-predicted. A numerical simulation is also presented using the ANSYS Autodyn 14.0 software. The results show that the numerical and analytical pressure evolution in the filling and the radial velocity of the jacket are in very good agreement, verifying the uniaxial strain assumption. This agreement (together with the experimental agreement) thus suggests that the RankineeHugoniot relations, the wave interactions and the radial rarefaction wave must all be included in the model to adequately describe the fragmentation of the PELE ammunition behind a thin target plate.

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

The ballistic behavior of four different armor ceramic materials with thicknesses varying from 3 mm to 14 mm has been investigated. These are two types of alumina Al2O3 armor grades and two types of SiC armor grades produced by different armor ceramic producers. The ballistic study has been performed using the standard DoP technique with two types of AP projectiles. The microstructure and the mechanical properties of the armor ceramics are investigated with SEM (Scanning Electron Microscopy), X-ray microanalysis, impulse excitation methods and Vickers hardness method. The microstructures are characterized by the number and chemical nature of the phases, the grain size, the type of fracture mode identified from SEM investigation of fragments. The measured mechanical properties are hardness, fracture toughness, flexural strength and the speed of sound (transversal and longitudinal). The ballistic tests are performed with two 7.62 mm projectiles AP8 (WC core) at 930 m/s and APM2 (hard steel core) at 800 m/s. The mass efficiency factor has been determined for each of the armor ceramics. The difference in the ballistic performance of the two alumina types is marginal. The two silicon carbide types are indistinguishable from ballistic point of view. The gained knowledge can be used two-fold: first, to understand better the influence of the microstructure on the ballistic performance of armor ceramics and second, as reference material for the development of a new class of armor ceramics.

The ballistic behavior of four different armor ceramic materials with thicknesses varying from 3 mm to 14 mm has been investigated. These are two types of alumina Al2O3 armor grades and two types of SiC armor grades produced by different armor ceramic producers. The ballistic study has been performed using the standard DoP technique with two types of AP projectiles. The microstructure and the mechanical properties of the armor ceramics are investigated with SEM (Scanning Electron Microscopy), X-ray microanalysis, impulse excitation methods and Vickers hardness method. The microstructures are characterized by the number and chemical nature of the phases, the grain size, the type of fracture mode identified from SEM investigation of fragments. The measured mechanical properties are hardness, fracture toughness, flexural strength and the speed of sound (transversal and longitudinal). The ballistic tests are performed with two 7.62 mm projectiles AP8 (WC core) at 930 m/s and APM2 (hard steel core) at 800 m/s. The mass efficiency factor has been determined for each of the armor ceramics. The difference in the ballistic performance of the two alumina types is marginal. The two silicon carbide types are indistinguishable from ballistic point of view. The gained knowledge can be used two-fold: first, to understand better the influence of the microstructure on the ballistic performance of armor ceramics and second, as reference material for the development of a new class of armor ceramics.

The interaction of thin ceramic tiles with AP8 (WC core, 7,62 mm) at 1000 m/s velocity has been studied experimentally and numerically. “Thin” ceramic tiles refers here to ratio of the tile thickness (t) to the projectile diameter, (d), t/d@ 1, as they are both in the same order. The method applied to visualize the penetration dynamics has been described. It consists of two orthogonal X-ray sources each of 1.2 MeV, coupled to high-speed camera and triggered by aluminum foil, placed in front of the ceramic tile. The time resolution of the experimental set-up is ±1 microsecond. The spatial resolution is ±0.2 mm. The size of the tiles that permit very good image quality is 50 mm x 50 mm. The penetration dynamics of AP8 projectile in SiC tile with thickness of 8 mm has been studied both with and without backing to distinguish the different failure mechanisms during the penetration process. The normalized penetration versus time (P,t) and normalized length of the projectile versus time (L,t) curves have been generated. The penetration dynamics of AP8 in the tile with backing is a non-linear process and three different stages, each corresponding to different penetration velocity, have been identified and described. The penetration behavior in the case of stand alone tile (without backing) has linear character. The finite element code LS-Dyna has been applied to gain the spatial and temporal stress distribution and study the observed phenomena numerically. Both numerical and experimental approaches are set complementary to improve the current understanding of fragmentation and penetration dynamics in thin ceramic tiles.

The interaction of thin ceramic tiles with AP8 (WC core, 7,62 mm) at 1000 m/s velocity has been studied experimentally and numerically. “Thin” ceramic tiles refers here to ratio of the tile thickness (t) to the projectile diameter, (d), t/d@ 1, as they are both in the same order. The method applied to visualize the penetration dynamics has been described. It consists of two orthogonal X-ray sources each of 1.2 MeV, coupled to high-speed camera and triggered by aluminum foil, placed in front of the ceramic tile. The time resolution of the experimental set-up is ±1 microsecond. The spatial resolution is ±0.2 mm. The size of the tiles that permit very good image quality is 50 mm x 50 mm. The penetration dynamics of AP8 projectile in SiC tile with thickness of 8 mm has been studied both with and without backing to distinguish the different failure mechanisms during the penetration process. The normalized penetration versus time (P,t) and normalized length of the projectile versus time (L,t) curves have been generated. The penetration dynamics of AP8 in the tile with backing is a non-linear process and three different stages, each corresponding to different penetration velocity, have been identified and described. The penetration behavior in the case of stand alone tile (without backing) has linear character. The finite element code LS-Dyna has been applied to gain the spatial and temporal stress distribution and study the observed phenomena numerically. Both numerical and experimental approaches are set complementary to improve the current understanding of fragmentation and penetration dynamics in thin ceramic tiles.

Currently, two methods exist to determine trajectory of a ballistic penetrator: Poncelet Analysis and Differential Area Force Law (DAFL) methods. An exact solution for the Poncelet Equation exists; making for easy computation. However, the one dimensional nature of the equation fails to capture the intricate three-dimensional nature of real world ballistic penetrator trajectories. The DAFL methods employ empirically derived stress algorithms to calculate to forces acting on a differential area of a projectile. These stresses are then used to determine the forces and moments acting on the differential areas. These forces and moments are then used to solve the equations of motion to determine the trajectory of the ballistic penetrator. The DAFL methods accurately capture the three dimensional nature of the penetrator's trajectory, but are computationally intensive which make them slow. The Integrated Force Law (IFL) method combines the computational ease of the Poncelet Analysis with the accuracy of the DAFL methods. In IFL, the projectile shape is modeled as a polynomial. The stress algorithms used in the DAFL methods are them numerically integrated over the top and bottom surfaces of the projectile to determine the force and moment acting on the top and bottom half of the weapon. These two forces and moments are then used to solve the equations of motion. J-hook trajectories are solved in less than 40 seconds and stable trajectories are solved in less than three seconds. http://archive.org/details/efficientcalcula109452532 Approved for public release; distribution is unlimited.

The Dutch Ministry of Defence has asked TNO to study mine neutralisation by small calibre projectile impact. This method would not demand the close approach of a suspected object. A single shot with a high accuracy weapon at a large stand-off will eliminate the danger and will allow for close approach to inspect the object after observing the necessary safety time. This paper discusses the laboratory study performed to evaluate the reactions of an Anti Personnel pressure activated mine, the Dutch AP- 22C1, both with and without detonator. These preliminary results show that mine neutralisation with small calibre projectile impact seems a promising technique (using .338″ AP, .50″ Ball or .50″ APIHC projectiles). However, armed mines (with detonator) could respond with a detonation, followed by unwanted collateral damage

TNO executed a technology demonstration programme in co-operation with RWMS on the application of solid fuel ramjet propulsion technology to medium calibre air defence projectiles. From 2000 to 2004 a complete and integrated structural and aero-thermodynamic projectile design was conceived satisfying the gun related requirements on projectile mass and length. The structural integrity during gun launch of this projectile including fuel was verified in test firings. A new free jet facility was developed at TNO which was used for aerodynamic heating experiments on projectile parts, for intake performance verification and for on-ground verification of the functioning of complete projectiles. Concluding flight tests demonstrated a very short ignition delay and a clear capability to maintain a flight speed of 1400 m/s. The successful demonstration of the thrust equal to drag capability of a solid fuel ramjet propelled projectile at Mach 4+ flight speed is a first for Europe and, as far as known, also for the world

TNO executed a technology demonstration programme in co-operation with RWMS on the application of solid fuel ramjet propulsion technology to medium calibre air defence projectiles. From 2000 to 2004 a complete and integrated structural and aero-thermodynamic projectile design was conceived satisfying the gun related requirements on projectile mass and length. The structural integrity during gun launch of this projectile including fuel was verified in test firings. A new free jet facility was developed at TNO which was used for aerodynamic heating experiments on projectile parts, for intake performance verification and for on-ground verification of the functioning of complete projectiles. Concluding flight tests demonstrated a very short ignition delay and a clear capability to maintain a flight speed of 1400 m/s. The successful demonstration of the thrust equal to drag capability of a solid fuel ramjet propelled projectile at Mach 4+ flight speed is a first for Europe and, as far as known, also for the world

The Dutch Ministry of Defence has asked TNO to study mine neutralisation by small calibre projectile impact. This method would not demand the close approach of a suspected object. A single shot with a high accuracy weapon at a large stand-off will eliminate the danger and will allow for close approach to inspect the object after observing the necessary safety time. This paper discusses the laboratory study performed to evaluate the reactions of an Anti Personnel pressure activated mine, the Dutch AP- 22C1, both with and without detonator. These preliminary results show that mine neutralisation with small calibre projectile impact seems a promising technique (using .338″ AP, .50″ Ball or .50″ APIHC projectiles). However, armed mines (with detonator) could respond with a detonation, followed by unwanted collateral damage