Armor Piercing Projectile Research Articles

Impact behavior and ballistic efficiency of armor-piercing projectiles with tool steel cores

Armor-piercing (AP) projectiles generally carry a hard core within a copper jacket. Upon impact on a hard target, the copper case is stripped, while the core pierces the target. The cores of the most efficient AP projectiles are built with either tungsten alloys or depleted uranium, but alloy steels are also commonly used, because they are less expensive and less polluting, even if they are much less efficient. The impact deformation and fracture behavior of armor-piercing projectiles fabricated with three different tool steel cores, and their resultant ballistic efficiency, are investigated, both to better understand the optimal mechanical properties of armor piercing materials, and to describe the impact fracture mechanics of the tested tool steels. Moreover, the ballistic results of the three tool steels are compared with those of plain medium-carbon steel and cemented tungsten carbide.

Procena početne brzine projektila kao rešenje problema granične vrednosti za dve tačke

The estimating of a projectile initial velocity is formulated as a two-point boundary value problem. To solve it, the data of a Doppler Radar or the results of solving the Cauchy problem can be used. The projectile initial velocity v0 estimation process is based on the numerical solution of a system of ordinary differential equations and the bisection method. The iterative calculating process is interrupted when a predetermined accuracy of a projectile initial velocity and a predetermined value of the width of velocity’s search interval is reached. In the article, the block diagram of the algorithm for the projectile initial velocity process is developed. The Mathcad program code for mathematical modeling and a computer simulation of the projectile initial velocity estimation process for a 57mm armor-piercing projectile of ZIS-2 anti-tank gun 1943 model is given.

Methodology to Measure the Protective Areal Density of Ceramic Tiles Against Projectile Impact

<p class="p1">The protective areal density of any armour material is the important property required for armour design. In this study, ballistic performance of hot pressed boron carbide tiles, with a tile thickness of 12.2 mm, was evaluated using the protective areal density (PAD) test method, against hard steel 12.7 mm armour piercing (AP) projectiles. The binary response data on complete penetration/ partial penetration obtained from PAD testing was fitted with the standard logistic regression model. A detailed discussion on statistical procedure has been presented. The PAD (pp = 0.5) was estimated to be 82.5 kg/m2 and the lower and upper bounds of 95 per cent confidence interval for (PAD) (pp = 0.5) was found to lie between 79.5 kg/m2 and 85.0 kg/m2.</p>

Numerical study on determining design parameters of wheeled armored vehicles

The survivability of the crew is the most important factor to be considered when designing the body of a military combat vehicle, and the design must protect against armor-piercing projectiles and mine blasts, in order to enhance survivability. In this paper, we propose a numerical approach that can be used in the initial design stage when designing military combat vehicles that provide adequate protection against ballistics and mines. First, the basic shape of the vehicle is defined based on an analysis of the dimensions of a similar vehicle, and the thicknesses of the front and side plates are determined by performing a ballistic impact simulation. For the bottom plate design, the primary design parameters and their values, such as the stand-off, bottom angle, bottom thickness, and bottom-side thickness, are defined. Next, the results of a main effect analysis and an analysis of variance for each design parameter are compared to the response indices representing the performance of the vehicle as determined based on the results of the blast impact simulation and then main effect parameters for each response index are confirmed. In addition, the suitable shapes and dimensions of the vehicle that can meet the armor-piercing projectiles and mine blast threat conditions and design constraints are determined from the blast impact simulation results of the design models determined by the design of experiments method.

Investigation on the ballistic behavior of mosaic SiC/UHMWPE composite armor systems

Abstract Experimental study on the ballistic behavior of mosaic Silicon Carbide (SiC) ceramics bonding with Ultra-High Molecular Weight Polyethylene (UHMWPE) plate is presented against 7.62 mm×51 mm Armor Piercing (AP) projectile. The effect of SiC ceramics on the ballistic performance of mosaic SiC/UHMWPE composite armors is systematically investigated, and the bulletproof process of the composite armor combining the hard/brittle SiC and soft/flexible UHMWPE is clarified in detail. The test results show that the ballistic performance of composite armors is significant influenced by the geometry of mosaic SiC ceramics and the impact zone of front layer, different impact zones are defined for the cylindrical mosaic SiC/UHMWPE composite armor. The residual velocities of AP projectile are varied from 648 m/s to 0 m/s for the cylindrical, hexagonal and square mosaic SiC ceramics, when the launch speeds of bullets are 780 m/s with a standard deviation of 10 m/s. The bulge lengths of UHMWPE plate are also changed from 16.5 mm to 43.2 mm for different structures of mosaic SiC ceramic front layer. The bulletproof property can be significantly enhanced by prolonging the interaction time between bullet and target. The conclusions of this paper are practically useful for designing the hard/flexible composite armor systems.

Effect of Prestressing Multilayer Steel Armor on Its Impact Resistance to Blunt Rigid Projectiles

This paper investigates numerically the enhancement of impact resistance of multiplayer steel armor to rigid and blunt projectiles. The monolithic armor always possesses higher ballistic resistance than the multilayer one of the same weight and areal density. In this work, the monolithic Weldox 460E steel armor is divided into three layers. The front and rear layers have the same thickness and they are thinner than the middle one. The thicker middle layer is prestressed by applying initial compressive strain. Then, the yield point of the middle layer is raised and the overall impact resistance of the prestressed multilayer armor is increased. The prestressed armor is impacted by a high-speed armor piercing (AP) blunt and rigid projectile. The impact resistance is macroscopically measured as the percentage reduction in the kinetic energy (KE) of the AP projectile. The percentage reductions in KE are calculated for the monolithic armor, equal and different thicknesses three layers armors with and without prestressing their middle layers. According to the presented computations, the maximum reduction in KE corresponds to the different thickness three layers armor having its thicker middle layer been prestressed.

An experimental and numerical investigation on ballistic performance of advanced composites

In this study, ballistic performance of aramid/epoxy and carbon-aramid/epoxy hybrid composites is investigated, experimentally and numerically. These composites were manufactured by vacuum-assisted resin infusion molding technique. 7.62 M61 type AP (Armor Piercing) projectiles were used in ballistic test of advanced composite materials. Six different impact velocities measured by a laser velocity measurement system were selected. Residual velocities were measured by velocity measurement traps from the back surface of the tested samples. For numerical study, ANSYS software was used as the pre-processor and LS-DYNA was used as the solver. Three different numerical models were created. After performing experimental tests and numerical simulations, ballistic limit velocities were calculated based on energy conservation. Numerical results are compared with the experimental ones and good agreements are obtained.

Numerical Study on the Ballistic Impact Response of Aramid Fabric- epoxy Laminated Composites by Armor Piercing Projectile

This paper presents the results from experiments and numerical simulations on the ballistic impact of 10mm thick aramid fabric-epoxy composite laminates by a 7.62mm armor piercing projectile at varying impact velocities. Post perforated residual velocity (RV), contact duration of projectile with the target and ballistic limit (BL) of composite were simulated using a finite element code HyperWorks-Radioss. Interaction of projectile with composite laminates was captured by high speed video. The predicted ballistic parameter from simulation compared well with the precision experimental results. The simulated energy and stress distribution during impact of projectile on composite laminate showed marked difference with variation in impact velocities (SV). The magnitude and duration of stress as well as the contact force was found to increase when projectile impacted at lower SV thus enhancing the extent of delaminating and the core damage area and the trend was reversed for higher SV. The findings corroborate the bullet inflicted damage of composite laminates experimentally determined by ultrasonic C-scan.

Effect of Tile Thickness and Projectile Velocity on the Ballistic Performance of Boron Carbide Against 12.7 mm AP

The high hardness combined with its lower density makes boron carbide an attractive candidate for armour material. The ballistic performance of hot pressed boron carbide tiles were evaluated using standard Depth of Penetration (DOP) test method against hard steel armour piercing (AP) projectile of 12.7 mm caliber. Aluminium alloy 2024-T351 was used as backing material. The effect of tile thickness on ballistic efficiency was studied for tile thickness from 7.1 mm to 14.6 mm. Also projectile velocity effect was studied for velocities between 700 to 825 m/s. The ballistic efficiency with respect to tile thickness was initially found to increase and then decreases. Results on ballistic efficiency along with results of post ballistic analysis have been presented.

Numerical Simulation of Ballistic Impact of Armour Steel Plate by Typical Armour Piercing Projectile

Ballistic impact of typical armour steel plate of medium thickness by ogive-nosed projectiles travelling with ordnance velocities has been investigated through numerical simulations. Johnson-Cook material and failure models have been used to simulate the behavior and failure of the material under impact conditions. The model constants have been derived from an experimental work done by the authors published previously. Simulation has been done in Altair-HyperWorks FE package. The stages of penetration have been predicted. The residual velocities, ballistic limit velocity andperforation times have been determined from the simulation results and found to match with experimental data.

Numerical simulation of armor capability of AI2O3 and SiC armor tiles

Alumina and Silicon Carbide armor plates have been tested numerically against 7.62x51 (mm x mm) armor piercing (AP) projectiles. A 2-D problem with axial symmetry has been designedand the simulations were carried out using commercial software ANSYS AUTODYN. Experiments were modeled for Alumina (99.5%), Alumina (99.7%) and SiC with a range of tile thicknesses (5, 10, 15 and 20 mm). The projectile was chosen as 7.62 x 51AP bullet (initial velocity 810 m/sec)with two different core materials Steel 4340 and WC, however, casing material was copper for both cores. SiC showed better defense against AP bullet as compared to Al2O3. The residual velocity and momentum of the bullet were found to decrease with increasing tile thickness. SiC tiles with thickness 15mm and 20 mm successfully sustained penetration against steel 4340 and WC core bullets, respectively. However none of the Alumina targets succeeded in stopping the bullet.

Investigation on high-velocity impact performance of multi-layered alumina ceramic armors with polymeric interlayers

In this study, ballistic behavior of multi-layered ceramic armors under high velocity impact is studied numerically. The model consists of 2D-axisymmetric Lagrangian approach with Johnson–Holmquist constitutive model for alumina ceramic tiles, Mie–Gruneisen equation of state for polymeric interlayers, and Johnson–Cook constitutive relation for Armor Piercing (AP) projectile. The finite element results obtained from various armor layups show the potentiality of multi-layered ceramic armor in extending conoid fracture through the ceramic layers, thus leading to the increase in the armor performance. It is illustrated that besides ceramic armor layup, interlayers of ceramic tiles have a significant role in increasing the armor performance. Finally, the effect of different polymeric interlayers on ballistic performance of multi-layered ceramic armors against AP projectile is investigated. In order to measure the ballistic performance of the armors, various criteria are introduced. Depth of penetration of the projectile in the armor, residual velocity of the projectile, time duration in which the projectile is engaged inside the armor, projectile tip erosion during impact, and interaction volume ratio are some of these criteria. The study indicates that armor layup with thin front ceramic tiles backed by thicker tiles shows better conoid fracture extension and often better ballistic performance. Furthermore, among the polymeric interlayers used between the ceramic tiles, polystyrene causes the best and nylon causes the worst ballistic performance in the armor.

An armour-piercing projectile penetration in a double-layered target of ultra-high-performance fiber reinforced concrete and armour steel: Experimental and numerical analyses

In this paper, experimental and numerical investigations are conducted to study the dynamic response of a double-layered target of ultra-high-performance fiber reinforced concrete (UHPFRC) and armour steel subjected to an armour-piercing projectile impact. Firstly, 9 shots of ogival/conical nose projectiles penetration test on three configurations of segmented UHPFRC target with armour steel are carried out. Based on the measured penetration depth in the backing target, the ballistic efficiency of the composite targets is then analyzed quantitatively via the Differential Efficiency Factor. The meso-scale Lattice Discrete Particle Model (LDPM), which accounts for rate effect and tensile fracture, is used as the constitutive model to describe the UHPFRC material mechanical response. While the armour steel material is modeled by Johnson–Cook yield criterion with finite element method. The numerical results of both failure mode and residual penetration depth are presented and evaluated with the experimental results. Consequently, the importance of UHPFRC conditions such as fiber content, lateral constrain, lamination is addressed with respect to the validated penetration tests. Finally, the UHPFRC plate ballistic properties are analyzed through extensive perforation simulations.

Response of steel-tube-confined concrete targets to projectile impact

Concrete is widely used in protective structures. Strength and toughness are two key factors for its anti-impact performance. Imposing constraint on concrete is an effective way to improve the anti-impact performance of concrete protective structures. In this paper, penetration tests of steel-tube-confined concrete (STCC) targets impacted by 12.7 mm armor piercing projectile (APP) at velocity around 820 m/s were conducted and different diameters and wall thicknesses of confining steel tube were considered. The typical damage modes of the tested STCC targets were obtained and influences of impact location, diameter and thickness of confining steel tube on the anti-penetration performance of STCC targets were also analyzed. The results show that the anti-penetration performance of STCC targets is obviously superior to that of semi-infinite concrete targets in restraint of the damage area and reduction of depth of penetration (DOP).

Design and impact resistant analysis of functionally graded Al2O3–ZrO2 ceramic composite

Gradient concept is one of the solutions in advanced material design and structure control. Functionally graded materials (FGMs) are materials which change their composition, constitution or structure continuously along the direction of thickness; the property and function of those materials appear as changeable gradient characteristics. In this research, powder metallurgy method was used to make the functionally graded Al2O3–ZrO2 composite, which was backed with 6061-T6 aluminum alloy plate. For comparing purpose, we also make multilayer Al2O3–ZrO2 composite and pure Al2O3 composite under the same areal density. Based on NIJ IV standard, ballistic test was executed on the three kinds of samples by using 0.30″ armor piercing projectile (AP). Finite element software ANSYS/LS-DYNA was also used to simulate stress distribution and fracture of these composites under impact. It was shown from ballistic test that FGM had the best impact resistant performance. Normally, multilayer ceramic structure will be fractured after impact because of the tensile wave caused by the interlayer. Through SEM observation, delamination was not found in the interlayer of FGM. This phenomenon reduced the tensile wave occurred in the interface between layers and delayed the crack propagation, resulting in a higher ballistic resistance capability structure.

Calculation and Verification on the Linear Instability of Shaped-Charge Jet Under Axial Pulse Current

To improve the defense capability of passive electromagnetic armor against shaped-charge jet (SCJ), according to the superposition principle and the linear perturbation theory, the SCJ disturbance control equations are constructed and the 3-D equation is reduced to 1-D equation, consequently, the instability growth rates of the pinch and kink of SCJ and the varying law of instability growth rates with time and yield stress are obtained under the axial pulse current, which indicate that the instabilities must occur as long as the perturbations exit. Meanwhile, the SCJ deformation can be calculated through numerical method. The pinching experiments with a 39.2-mm diameter armor-piercing projectile proceeded when the charging voltage is 5370 V and the peak current is 140 kA. The kinking experiments with a 1.75-mm diameter copper wire proceeded when the charging voltage is 5140 V and the peak current is 43 kA. The experimental results demonstrate that axial pulse current can destroy the SCJ because of necking or kinking perturbation and confirm the validity of the theoretical analysis.

Failure mechanisms in ballistic performance of Ti–6Al–4V targets having equiaxed and lamellar microstructures

The relationship between the failure mechanism and the microstructural features of the Ti–6Al–4V targets was established in this paper. The 12.7 mm armour piercing (AP) projectiles were fired against the Ti–6Al–4V targets having equiaxed and lamellar microstructures with thickness ranging from 30 to 45 mm. Ductile hole enlargement characterized by delamination and spall fragments from the rear surface was observable in the Ti–6Al–4V targets having equiaxed microstructure, while brittle fragmentation characterized by plugging and star fragments from the rear surface was observable in the Ti–6Al–4V targets having lamellar microstructure. The distinctly different propagating features of adiabatic shear bands in Ti–6Al–4V targets having equiaxed and lamellar microstructures determined the failure mechanism analyzed. In the equiaxed microstructure, the regularly spaced propagating features of adiabatic shear bands facilitated the failure mechanism of ductile hole enlargement. In the lamellar microstructure, the net-like propagating features of adiabatic shear bands facilitated the failure mechanism of brittle fragmentation.

On the Influence of Fracture Criterion on Perforation of High-Strength Steel Plates Subjected to Armour Piercing Projectile

Abstract This paper presents a numerical investigation of fracture criterion influence on perforation of high-strength 30PM steel plates subjected to 7.62x51 mm Armour Piercing (AP) projectile. An evaluation of four ductile fracture models is performed to identify the most suitable fracture criterion. Included in the paper is the Modified Johnson-Cook (MJC) constitutive model coupled separately with one of these fracture criteria: the MJC fracture model, the Cockcroft-Latham (CL), the maximum shear stress and the constant failure strain models. A 3D explicit Lagrangian algorithm that includes both elements and particles, is used in this study to automatically convert distorted elements into meshless particles during the course of the computation. Numerical simulations are examined by comparing with the experimental results. The MJC fracture model formulated in the space of the stress triaxiality and the equivalent plastic strain to fracture were found capable of predicting the realistic fracture patterns and at the same time the correct projectile residual velocities. However, this study has shown that CL one parameter fracture criterion where only one simple material test is required for calibration is found to give good results as the MJC failure criterion. The maximum shear stress fracture criterion fails to capture the shear plugging failure and material fracture properties cannot be fully characterized with the constant fracture strain

Comparison of numerical and experimental study of armour system based on alumina and silicon carbide ceramics

Abstract The main goal of this numerical and experimental study of composite armour systems was to investigate their ballistic behaviour. Numerical simulations were employed to determine the initial dimensions of panel layers before the actual ballistic test. In order to achieve this aim, multivariate computations with different thicknesses of panel layers were conducted. Numerical calculations were performed with the finite element method in the LS-DYNA software, which is a commonly used tool for solving problems associated with shock wave propagation, blasts and impacts. An axisymmetric model was built in order to ensure sufficient discretization. Results of a simulation study allowed thicknesses of layers ensuring assumed level of protection to be determined. According to the simulation results two armour configurations with different ceramics have been fabricated. The composite armour systems consisted of the front layer made of Al2O3 or SiC ceramic and high strength steel as the backing material. The ballistic performance of the proposed protective structures were tested with the use of 7.62 mm Armour Piercing (AP) projectile. A comparison of impact resistance of two defence systems with different ceramic has been carried out. Application of silicon carbide ceramic improved ballistic performance, as evidenced by smaller deformations of the second layer. In addition, one of armour systems was complemented with an intermediate ceramic-elastomer layer. A ceramic-elastomer component was obtained using pressure infiltration of gradient porous ceramic by elastomer. Upon ballistic impact, the ceramic body dissipated kinetic energy of the projectile. The residual energy was absorbed by the intermediate composite layer. It was found, that application of composite plates as a support of a ceramic body provided a decrease of the bullet penetration depth

Optimization of two-component armour

Abstract The paper presents research on optimization of two-layer armour subjected to the normal impact of the 7.62x54 B32 armour piercing (AP) projectile. There were analysed two cases in which alumina Al2O3 was supported by aluminium alloy AA2024-T3 or armour steel Armox 500T. The thicknesses of layers were determined to minimize the panel areal density whilst satisfying the constraint, which was the maximum projectile velocity after panel perforation. The problem was solved through the utilization of LS-DYNA, LS-OPT and HyperMorph engineering software. The axisymmetric model was applied to the calculation in order to provide sufficient discretization. The response of the aluminium alloy, armour steel and projectile material was described with the Johnson-Cook model, while the one of the alumina with the Johnson-Holmquist model. The study resulted in the development of a panel optimization methodology, which allows the layer thicknesses of the panel with minimum areal density to be determined. The optimization process demonstrated that the areal density of the lightest panel is 71.07 and 71.82 kg/m2 for Al2O3-Armox 500T and Al2O3-AA2024-T3, respectively. The results of optimization process were confirmed during the experimental investigation.