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Ballistic resistance is affected by the projectile and armor material used. The character and behavior of the projectile affects its ability to damage and penetrate armor. The velocity, mass and shape of the projectile are the main factors in determining the ability of the projectile to penetrate armor in this case the target plate. Therefore, this study aims to determine and analyze the effect of projectile mass and shape on the velocity with which it penetrates the armor material using a compressed air gun. Armor material as a ballistic test target using carbon steel plate with a thickness of 0.8 mm; 1.2 mm and 1.8 mm. Projectiles of lead materials with different masses and shapes are fired from the air gun under controlled air pressure, set at 2000 Psi, 3000 Psi, and 4000 Psi to provide thrust in the barrel. The plat target is placed at a distance of 5 m from the air gun. Speed gauges are placed after the air gun and after the target plate to determine the projectile's rate before and after passing through the target plate. The test results concluded that the velocity of the projectile ejected from the compressed air gun was influenced by the magnitude of the pressure and the mass of the projectile. The mass of the projectile has a more dominant effect on the velocity of the projectile compared to the amount of pressure applied. Different projectile shapes with the same mass have no significant effect on the velocity. However, the heavier mass projectile outperforms the lighter mass projectile through the target plate. It is required the right combination of velocity and mass of the projectile to be able to penetrate the target plate. [ABSTRACT FROM AUTHOR]

This paper presents the results of an investigation of the ballistic limits and failure modes of AA2024-T351 sheets impacted by cubical projectiles. The effect of cube orientation on the ballistic limit and failure modes was considered in detail. Three impact configurations were investigated. Configuration one, two and three considered face, edge or corner impacts correspondingly. The experimental results were complemented with finite element analysis results in order to explain the observations. The lowest ballistic limit (202 m/s) was observed when the cube edge impacted on the target. In the cube face impacts, the ballistic limit was higher (223 m/s), and the highest ballistic limit (254 m/s) was observed for the corner impact. Although the face impact did not have the lowest ballistic limit, this impact configuration resulted in the least amount of projectile energy loss for impacts above the ballistic limit. With the aid of finite element modelling, it was possible to develop a better understanding of the test results and explain that the observed differences in impact response were not just due to a difference in projectile frontal area, but also due to the combination of the localised deformation near the projectile impact point and the resulting global (dishing) deformation. [ABSTRACT FROM AUTHOR]

This paper presents the computational-based ballistic limit of laminated metal panels comprised of high strength steel and aluminium alloy Al7075-T6 plate at different thickness combinations to necessitate the weight reduction of existing armour steel plate. The numerical models of monolithic configuration, double-layered configuration and triple-layered configuration were developed using a commercial explicit finite element code and were impacted by 7.62 mm armour piercing projectile at velocity range of 900 to 950 m/s. The ballistic performance of each configuration plate in terms of ballistic limit velocity, penetration process and permanent deformation was quantified and considered. It was found that the monolithic panel of high-strength steel has the best ballistic performance among all panels, yet it has not caused any weight reduction in existing armour plate. As the weight reduction was increased from 20-30%, the double-layered configuration panels became less resistance to ballistic impact where only at 20% and 23.2% of weight reduction panel could stop the 950m/s projectile. The triple-layered configuration panels with similar areal density performed much better where all panels subjected to 20-30% weight reductions successfully stopped the 950 m/s projectile. Thus, triple-layered configurations are interesting option in designing a protective structure without sacrificing the performance in achieving weight reduction. [ABSTRACT FROM AUTHOR]

The concept of ballistically equivalent metals for ductile plate perforation has been defined and demonstrated for five aluminium alloys. Heuristic derivation of a semi-empirical relation between specific cavitation energy s c and hole slenderness ratio h / D (the ratio between plate thickness h and projectile nose base diameter D which is also known as the normalized plate thickness) has exposed a logarithmic dependence which is verified by experimental data. A closed-form logarithmic expression for s c which takes into account the h / D effect has led to a closed-form formula for the ballistic limit. The expression for s c is based on the spherical cavitation yield stress Y c S which serves as a scaling yield stress for strain-hardening (softening) response. It is found that ballistically equivalent metals should have practically the same values of Y c S and elastic modulus. The perforation of aluminium targets by 7.62 mm APM2 bullets is discussed and vast amount of experimental data is used to validate the particular ballistic limit formula. Application of the closed-form model is also demonstrated with connection to the more general concept of ballistically equivalent targets . The h / D effect on perforation of multilayered targets is examined and it is found that for ductile plate perforation the ballistic limit of a monolithic target is higher than the ballistic limit of any combination of its air-gapped parts. Under the constraint of n air-gapped protective layers with total thickness h the minimum ballistic limit is obtained for n identical layers. [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]

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. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of projectile diameter is studied on ballistic limit of thin aluminum plates. [•] Ballistic limit has been found to increase with increase in projectile diameter. [•] Monolithic target offered better resistance than layered target. [•] Behavior of target remained same against rigid and deformable projectile. [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: In this paper, the ballistic behavior of single, double-, three-, four- and six-layered plates impacted by hemispherical-nosed projectiles were experimentally investigated. Ballistic limit velocity for each multi-layered target was obtained based on the investigation of the effect of the air gap between layers, the number, order and thickness of layers on the ballistic resistance. The results showed that the monolithic thin targets presented more effective than multi-layered targets when the dominant response of monolithic targets were dishing and bulging which involved bending and stretching, and the ballistic limit velocities of multi-layered plates increased with the increase of the number of layers, although the multi-layered targets were less effective than monolithic targets. However, the monolithic targets had lower ballistic resistance than multi-layered targets if the total thickness above a specific value, the dominant target response changed from shearing to bulging and dishing when using multi-layered targets instead of monolithic targets. Moreover, the air gap decreased the ballistic resistance of multi-layered targets, but the air gap size had slight influence on the ballistic resistance. The order of layers affected the ballistic resistance of multi-layered targets, the multi-layered targets of two equal thick plates had the highest ballistic resistance followed by multi-layered targets of a thicker front plate and a thinner back plate, multi-layered targets of a thinner front plate and a thicker back plate. [Copyright &y& Elsevier]

The article describes the method of determination of limit velocity for the aluminium alloy sheet metal from the airplane fuselage skin hit by a pistol projectile of calibre 9 mm with utilisation of 2D FEM model of interaction between the projectile and the sheet metal. The simulations are based on accomplished firing experiments and results are compared. The results of simulation can be utilised for prediction of level of damage of aircraft fuselage in case of firing on board of the plane. [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]

This article deals with the perforation of ductile metal plates subjected to impact by flat-nosed projectiles at normal incidence. Generally speaking, ductile metal plates under impact by flat-ended missiles can fail either by global deformation combined with local shear rupture or by localized adiabatic shear plugging depending upon the geometrical and thermo-mechanical properties of both the targets and the projectiles. Modification is first made to the Bai-Johnson model for adiabatic shear plugging by taking account of strain rate effects using a thermo-viscoplastic constitutive equation instead of thermo-plastic material model and equations for the energy dissipated in the perforation process (perforation energy), the ballistic limit and the residual velocity are then obtained. Furthermore, a critical condition is obtained for differentiating localized adiabatic shear plugging from simple shear plugging failure with global deformations by comparing the modified Bai-Johnson model and the Wen-Jones model. It transpires that the present theoretical predictions are in good agreement with available experimental data in terms of the ballistic limits and the critical transition condition for the modes of plugging failure of ductile metal plates subjected to impact by flat-nosed missiles. It also transpires that the present model predicts well the residual velocities and the energies dissipated in the perforation process. [ABSTRACT FROM AUTHOR]

Abstract: The testing methodology for transparent armour is described. The focus of this paper is on the assessment of the protective strength of transparent ceramics being used in transparent armour systems. Not only the ballistic testing method but also experimental techniques which allow the visualization of damage and the projectile penetration are discussed. Visualization techniques are essential for understanding the mechanisms of interaction between projectile and target material. Ballistic tests results, high-speed photographs and flash-radiographs from experiments with transparent armour are presented. [Copyright &y& Elsevier]

Abstract: This paper examines the penetration and perforation of fibre-reinforced plastic (FRP) laminates struck by rigid projectiles with different nose shapes within a wide range of impact conditions using ABAQUS/Explicit code. It is assumed that the FRP laminate target response can be represented by a velocity dependent forcing function which eliminates discretizing the target as well as the need for a complex contact algorithm. The forcing function is then applied to the surface of the projectiles as boundary conditions in the numerical model. With this combined analytical and computational technique we can obtain the depth of penetration, residual velocity, ballistic limit, transient response in terms of time-histories of displacement/penetration, velocity and deceleration of the projectile. It is shown that the model predictions are in good correlation with available experimental data. [Copyright &y& Elsevier]

Ballistic impact tests were conducted using hard steel cylindro-conical projectiles of mass ranging between 550 to 570gms with three nose geometries against unidirectional glass-fiber reinforced epoxy composite plates of varying stacking sequence and thickness. Gas gun projectile launcher setup was used to accelerate the projectiles. The damage evolution, failure pattern, ballistic limit and energy absorption by each target set were determined experimentally. Experimental study shows that the nose geometry of heavy projectile has very less influence on the energy absorption and ballistic limit for thin targets whereas it plays a major role with increasing thickness of the laminates. It was also confirmed from the experimental study that delamination was not a major failure mechanism for thin laminates but has considerable effect on thick laminates. Severe delamination and damage were observed in thick laminates. Varying the stacking sequence neither showed marked deviation in ballistic limit nor energy absorption, but showed difference in delaminated area especially in thick targets. Results show that, while the amount of energy absorbed by the composite was different for all three projectiles, they showed similar trends - energy absorbed increased with velocity up to a critical impact velocity before it starts to decrease. A mathematical model based on energy balance principle and resistive forces acting on the projectile during perforation was developed to theoretically calculate the ballistic limit. The theoretical value correlates well with the experimental value. [ABSTRACT FROM AUTHOR]

The oblique and normal perforation of a concrete target subjected to a rigid projectile impact is studied in this paper. A general three-stages model, i.e., initial cratering, tunnelling and shear plugging, is developed based on dynamic cavity expansion theory and plug formation. Analytical solutions for the ballistic performance and the perforation limit of concrete target are obtained. The proposed formulae are consistent with other empirical formulae and correlate well with the experimental data. [Copyright &y& Elsevier]