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Mechanisms of projectile defeat and ballistic resistance of thin targets impacted by tip-deformable conical projectiles have been discussed in the context of the influence of apex angle of the projectile. Transition in target local failure modes occurred as the projectile apex angle was altered. The effect on projectile deformation and ballistic properties has also been discussed. A brief discussion on projectile deformation mechanism and projectile defeat near ballistic limit velocities with supporting experimental evidence is included. Numerical simulation using ABAQUS/Explicit has been able to effectively predict the projectile deformation and associated target behavior. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study, the penetration behaviour of a Mild Steel Cored (MSC) round, 7.62 mm in diameter and 39 mm in length, commonly known as the AK47 round, was studied since it still forms an important part of the threat spectrum for personnel body armour systems. Likewise, boron carbide strike face materials were selected since this armour material is often the material of choice for ultralightweight body armour systems for protection against this particular threat. The presence of two, relatively soft, intermediate materials (the copper jacket and filler material of the bullet, and a fibre-reinforced polymer cladding layer on the ceramic) between the mild steel core and the boron carbide target was examined using reverse ballistics techniques, flash x-radiography and round recovery measurements. This was supported by selective numerical simulations using the computer code ANSYS-AUTODYN. It was found that stripping of the jacket, from the AK47 MSC rounds, makes a difference to its penetrating ability: the mild steel core is significantly reduced in length, and mass, when the jacket is not present. The magnitude of this effect is much greater than previously reported for high-strength steel-cored rounds and for tungsten carbide-cored rounds. The penetration event appears to be a twostage process: mushrooming of the mild steel core on, or near, the surface of the ceramic, followed by a linear erosion process as the core penetrates the ceramic itself. The second step has not been reported previously for MSC rounds. [ABSTRACT FROM AUTHOR]

The ballistic performance of thin aluminium targets and influence thereon of different circumferential fixity conditions were studied both experimentally and by finite element simulations. A pressure gun was employed to carry out the experiments while the numerical simulations were performed on ABAQUS/Explicit finite element code using Johnson–Cook elasto-viscoplastic material model. 1 mm thick 1100-H12 aluminium plates of free span diameter 255 mm were normally impacted by 19 mm diameter ogive and blunt nosed projectiles. The boundary conditions of the plate were varied by varying the region of fixity along its circumference as 100%, 75%, 50% and 25% in experiments and the numerical simulations. Further, simulations were carried out to compare the response of the plates with 50% and 75% continuous fixity with those with two and three symmetrical intermittent regions of 25% fixity respectively. The variation in the boundary condition has been found to have insignificant influence on the failure mode of the target however; it significantly affected the mechanics of target deformation and its energy absorption capacity. The ballistic limit increased with decrease in the region of fixity. It decreased for intermittent fixity in comparison with equivalent continuous fixity. And, it has been found to be higher for the impact with projectile having blunt nose in comparison with the one having ogive nose. [ABSTRACT FROM AUTHOR]

This study aims to investigate the penetration of a projectile into a surrogate human tissue numerically, using Finite Element (FE) simulation. 20% Balistic Gelatin material (BG) is simulated with an elasto-plastic hydrodynamic constitutive law, and then impacted by steel spheres at different velocities. The results from the FE simulations are compared with existing experimental data and other analytical equations from the literature. To our knowledge, this is the first study to investigate a projectile penetration by numerical simulation, and then compare the results with analytical and experimental data from previous studies. This developed model gives encouraging results for further investigations of penetrating impact of projectile in the human body. [ABSTRACT FROM AUTHOR]

Abstract: The paper describes a numerical study on the perforation of sheet steel by a projectile under high impact velocity to predict the ballistic behaviour and, in particular the ballistic limit. The parametric study is performed for several of the important variables in the numerical model using Abaqus/Explicit finite element code and their effects are reported in the paper. The variables considered include the target configuration (thickness), constitutive material model of the target, mass of the projectile, friction between the projectile and the target and shape of the projectile. The effect of the material behaviour was also studied through the use of two constitutive relations and to conclude the ballistic curves were calculated for several different target materials using data from literature. The numerical results were compared with existing data sourced from the literature and an analytical model was used to compare the trend obtained using numerical simulations in terms of ballistic limit. [Copyright &y& Elsevier]

Abstract: Three-dimensional numerical simulations were carried out with ABAQUS/Explicit finite element code to study the influence of target span and configuration on its ballistic limit. 1 mm thick 1100-H12 aluminum targets of varying span diameter and configuration were impacted by blunt and ogive nosed projectiles of 19 mm diameter and 52.5 g mass. The effect of target span was studied by varying the span diameter of 1 mm thick monolithic target as 50 mm, 100 mm, 204 mm, 255 mm and 500 mm. The effect of configuration was studied by taking the monolithic, double layered in-contact and double layered spaced targets of 1 mm equivalent thickness and 255 mm span diameter. The spacing between the layers was varied as 2 mm, 5 mm, 10 mm, 20 mm and 30 mm. In each case the target was impacted normally by blunt and ogive nosed projectile to obtain the ballistic limit. The highest ballistic limit was observed for monolithic target followed by layered in-contact and spaced targets respectively. The variation of spacing between the layers did not have significant influence on the ballistic limit in the case of ogive projectile but some effect was seen in the case of blunt projectile. The ballistic limit was found to increase with increase in target span diameter for both the projectiles and it was found to be higher for blunt nosed projectile as compared to that of ogive nosed projectile for all the spans considered excepting in the case of 50 mm span for which it was higher for ogive nosed projectile. [Copyright &y& Elsevier]

In the design and development of solid propellant rocket motors, the use of numerical tools able to predict the behavior of a given motor is particularly important in order to decrease the planning times and costs. This paper is devoted to present the results of the internal ballistics numerical simulation of the NAWC tactical motor n. 6, from ignition to burn-out, by means of a quasi-one-dimensional unsteady numerical simulation model, SPINBALL, coupled with a three-dimensional grain burnback model, GREG. In particular, the attention is focused on the effects on the SRM behavior of the erosive burning, total pressure drops and the cause of the pressure overpeak occurring during the last part of the ignition transient. The final objective is to develop an analysis/simulation capability of SRM internal ballistics for the entire combustion time with simplified physical models, in order to have reduced the computational costs, but ensuring an accuracy greater than the one usually given by zero-dimensional models. The results of the simulations indicate a very good agreement with the experimental data, as no attempt of submodels calibration is made, enforcing the ability of the proposed approach to predict the SRMs internal flow-field conditions. The numerical simulations show that NAWC n. 6 internal ballistics is completely led by the erosive burning, that is the root cause of the pressure peak occurring immediately after the SRM start-up. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and finite-element investigation of ballistic limit of thin single and layered aluminium target plates. Blunt-, ogive- and hemispherical-nosed steel projectiles of 19 mm diameter were impacted on single and layered aluminium target plates of thicknesses 0.5, 0.71, 1.0, 1.5, 2.0, 2.5 and 3 mm with the help of a pressure gun to obtain the ballistic limit in each case. The ballistic limit of target plate was found to be considerably affected by the projectile nose shape. Thin monolithic target plates as well as layered in-contact plates offered lowest ballistic resistance against the impact of ogive-nosed projectiles. Thicker monolithic plates on the other hand, offered lowest resistance against the impact of blunt-nosed projectiles. The ballistic resistance of the layered targets decreased with increase in the number of layers for constant overall target thickness. Axi-symmetric numerical simulations were performed with ABAQUS/Explicit to compare the numerical predictions with experiments. 3D numerical simulations were also performed for single plate of 1.0 mm thickness and two layered plate of 0.5 mm thickness impacted by blunt-, ogive- and hemispherical-nosed projectiles. Good agreement was found between the numerical simulations and experiments. 3D numerical simulations accurately predicted the failure mode of target plates. [ABSTRACT FROM AUTHOR]

Rarefaction wave gun (RAVEN) propulsion has renewed interest in the fundamental limits of recoil reductions attainable by redirecting propellant gases rearward from a gun without compromising the projectile propulsion. Compared with a conventional gun there is a great difference in the launch process and launch structure. This paper is concerned with an analysis of the dynamic characteristics of this high performance weapon system by numerical simulation. Based on its launch mechanism and launch structure, the vibration equation describing the vibration characteristics of RAVEN was established by vibration theory, which considered the actual movement of the projectile and inertial breech by coupling the interior ballistic equations of the rarefaction wave gun. A rigid-flexible dynamic model, which considered the coupling effect between the elastic vibration of the launch barrel and the dynamic behaviors of the other parts of the RAVEN, is established via a subsystem method. The vibration response of RAVEN during the launch is analyzed by numerical simulation. Comparisons are presented based on the conventional gun, as well as the rules of how the different parameters affect the vibration response. During the launching of RAVEN, the launch barrel shows significant vibration due to the effect of the propellant gases, the inertial breech, and the projectile, and there is some reduction in the vibration amplitude compared with that observed in a conventional closed chamber gun. The vibration amplitude and duration of the launch barrel, which increased with a decrease in the loading density, an increase in the mass of the inertial breech and projectile, and a delay of the venting time, is affected in a more significant manner by changes in loading density and the mass of projectile. The coupled effect between the launch barrel and the other parts of RAVEN are most prevalent in the z-direction. The vibration amplitude along the z-direction is higher than that of the y-direction. When the coupled effect is considered, the transverse vibration response of the flexible barrel has some reduction compared with the one that does not exhibit the coupling effect. [ABSTRACT FROM AUTHOR]