Steel Core Projectiles Research Articles

Fragmentation of an armour piercing projectile after impact on composite covered alumina tiles

In a typical body armour system, a hard armour plate is often used in conjunction with a soft ballistic panel. The main purpose of the armour plate is to erode and fragment an impacting projectile, such as 7.62 mm armour piercing (AP) projectiles with a very hard material core. This is made possible by employing a single ceramic tile as the strike face. This tile is covered by a sheet material. The sheet cover may improve the ballistic performance by partly maintaining the integrity of the ceramic. In this study, the effect of adding a composite cover has been investigated experimentally by ballistic testing of different types of composite-covered targets. The targets were totally perforated by a 7.62 mm AP hard steel core projectile at near-muzzle velocities (around 800 m/s). The post-impact process was monitored by high speed video, and the resulting core fragments were collected and analysed. This allowed the core fragmentation, residual velocity and kinetic energy-loss to be quantified. The results showed that the core fragmentation and the kinetic energy-loss of the projectile were most significant for the targets with the composite-cover on the back of the alumina. For targets with four composite back-layers, and an increased areal density of 9.5%, the mass of the projectile core was reduced by 61%, while the kinetic energy was reduced by 84%. The residual velocity did not vary to the same extent between the different target configurations. The mechanism behind the positive effect of a back cover is believed to be delayed opening of tensile cracks that originate from the back of the ceramic, which gives more time for interaction with the penetrator.

Influence of Impact Velocity and Steel Armour Hardness on Breakage of Projectile 14.5 × 114 API/B32

The goal of this article was focused on the study of projectile breakage after impact on steel armour depending on projectile impact velocity and steel armour hardness. Steel armour samples of hardness HBW500 and HBW600 were impacted by steel core projectile 14.5×114 API/B32 using three different impact velocities. The depth of the projectile penetration into steel armour of hardness HBW400, which was placed 65 mm behind the steel armour samples, was measured. The projectile remains after each impact were searched for their evaluation. For better visualization of the projectile breaking process after the impact on steel armour, the numerical simulations were performed. Experimental and numerical results were compared and combined in a graph showing the dependence of the depth of penetration on the projectile impact velocity for two different steel armour hardnesses and with indication of projectile coherence after impact.

Effect of viscoelastic behaviour of glass laminates on their energy absorption subjected to high velocity impact

In the present work, a comparative study is carried out on the energy absorption ability of phenolic and epoxy matrices reinforced with glass fibres. E-glass/phenolic and E-glass/epoxy laminates having different thickness (5mm, 10mm, 15mm, 20mm & 25mm) were fabricated and subjected to ballistic impact against 7.62×39mm mild steel core projectile. Dynamic Mechanical Analysis (DMA) of E-glass/phenolic and E-glass/epoxy laminates was also carried out. It was observed that, E-glass/phenolic laminates which have shown higher storage and loss modulus were found to show higher energy absorption than E-glass/epoxy laminates which have shown lower storage and loss modulus. This is observed to be because of ease of delamination and transverse stretching of fibres in E-glass/phenolic laminates as the matrix at the interface is allowing easy sliding. However this effect is found to be significant only when the laminate thickness to projectile diameter ratio (t/d) is more than two. Mechanisms influencing the observed trend in results are analyzed in the present paper with the help of DMA and high speed video imaging during impact. Failure analysis of laminates was studied by using microscopy techniques.

Behavior of E-glass composite laminates under ballistic impact

Abstract The use of light weight armor against ballistic threats is very important for increasing mobility and survivability. This paper describes ballistic performance of an E-glass/phenolic composite as a function of laminate thickness and projectile impact velocity using mild steel core projectile. The results show that there is a nonlinear relationship between the energy absorption and laminate thickness. The effect of thickness and velocity on energy absorption in the laminates has been explained in terms of interaction time between target and projectile. It is also observed that deformation of the projectile is more dependent on the target thickness than the strike velocity. Changes in failure mechanisms with change in target thickness are also described.

Perforation of 6082-T651 Aluminum Plates with 7.62 mm APM2 Bullets at Normal and Oblique Impacts

We conducted an experimental study to understand the mechanisms and dominant parameters for 7.62 mm APM2 bullets that perforate 6082-T651 aluminum armor plates at oblique impacts. The 7.62-mm-diameter, 10.7 g, APM2 bullet consists of a brass jacket, lead filler, and a 5.25 g, ogive-nose, hard steel core. The brass and lead were stripped from the APM2 bullets by the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel cores. These projectiles were fired from a rifle to striking velocities between 400 and 1,000 m/s into 20-mm-thick plates at normal impact (β = 0o) and at oblique angles of β = 15o, 30o, and 45o. Measured residual and ballistic-limit velocities for the full bullet and the hard core were within a few percent for normal impact and all oblique angles. Thus, we showed that the perforation process was dominated by the hard steel core of the bullet. In addition, we conducted large strain, compression tests on the 6082-T651 plate material for input to perforation equations derived from a cavity-expansion model for the steel core projectiles. Model predictions were shown to be in good agreement with measured ballistic-limit and residual velocity measurements for β = 0o, 15o, and 30o. We also presented a scaling law for the bullet that showed the ballistic-limit velocities were proportional to the square root of the product of plate thickness and a material strength term.

Experimental studies on the effect of size and shape of holes on damage and microstructure of high hardness armour steel plates under ballistic impact

In the present work the effect of size and shape of regularly spaced holes on the ballistic impact behavior of high hardness steel plates has been studied. Thick backing technique was used to evaluate the efficiency of these plates when subjected to ballistic impact of 7.62mm non-deformable hard steel core projectiles. The ballistic efficiency of these steel plates was found to be sensitive to size of the holes. Higher efficiency was found for plates with hole sizes close to the diameter of the projectile. Damage patterns and microstructure of the perforated steel plate have been compared with those of non-perforated steel plates. It has been found that presence of holes inhibits shear band formation in the target plates.

Development of an ultrahigh strength low alloy steel for armour applications

The present paper describes a steel with yield strength exceeding 1900 MPa and fracture toughness in the range of 40–50 MPa m1/2, in its optimum heat treated condition. Its strength is similar to that of 18 Ni (300) grade of maraging steel with good fracture toughness. When tempered at 300°C, it shows tempered martensite along with a small amount of retained austenite phase. The steel shows nearly 25% reduction in weight over typical rolled homogeneous armour (RHA) steel against high velocity hard steel core projectiles. The processing, microstructure, mechanical and ballistic properties of the steel are demonstrated.

The Effect of Crystallization and Ion Exchange to the SLS Glass for High-Strength Transparent Bulletproof Materials

Abstract:A transparent bulletproof materials of soda-lime-silicate(SLS) glass has been ballistically tested after impacting by 5.45mm AK-74 steel core projectiles at distance of 50 meters. The thickness of satisfaction on bulletproof test was about 30mm. For application of transparent bulletproof materials, the SLS glass was heated by crystallization and ion exchange. The Vickers hardness, fracture toughness, and bending strength of crystallized SLS glass was about 704Hv, 0.9409MPa∙m1/2, and 452MPa which is about 24%, 31%, 201% higher than parent SLS glass, respectively. The vickers hardness, fracture toughness, and bending strength of ion exchanged SLS glass was about 657Hv, 0.7337MPa∙m1/2, and 791MPa which is about 16%, 2%, 430% higher than parent SLS glass, respectively. Transmittance of heat treated and SLS glass was decreased slightly at the visible range. The results prove that light-weight bullet proof can be fabricated by crystallization and ion exchange technique of SLS glass.

Perforation of 7075-T651 Aluminum Armor Plates with 7.62 mm APM2 Bullets

We conducted an experimental and analytical study to better understand the mechanisms and dominant parameters for 7.62 mm APM2 bullets that perforate 7075-T651 aluminum armor plates. The 7.62-mm-diameter, 10.7 g, APM2 bullet consists of a brass jacket, lead filler, and a 5.25 g, ogive-nose, hard steel core. The brass and lead were stripped from the APM2 bullets by the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel cores. These projectiles were fired from a rifle to striking velocities between 600 and 1,100 m/s. Targets were 20 and 40-mm-thick, where the 40-mm-thick targets were made up of layered 20-mm-thick plates in contact with each other. The measured ballistic-limit velocities for the APM2 bullets were 1% and 8% smaller than that for the hard steel cores for the 20 and 40-mm-thick targets, respectively. Thus, the brass jacket and lead filler had a relatively small effect on the perforation process. Predictions from a cylindrical cavity-expansion model for the hard steel core projectiles are shown to be in good agreement with measured ballistic-limit and residual velocity data. The results of this study complement our previous paper with 5083-H116 aluminum target plates in that the ultimate tensile strength of 7075-T651 is about 1.8 times greater than that of 5083-H116. We also present a scaling law that shows a square root relationship between ballistic-limit velocity and plate thickness and material strength.

Effect of heat treatment on mechanical and ballistic properties of a high strength armour steel

In the present study an ultra high strength armour steel was austenatised at 910°C followed by tempering at 200, 300, 400, 500 and 600°C. After heat treatment the properties of tensile strength, ductility, charpy impact strength, hardness and microstructure were evaluated from the mechanical tests and metallographic analysis respectively. The ballistic behavior of the heat-treated plates was evaluated impacting against non-deformable hard steel core projectiles at 840 ± 15 m/s at normal angle of attack. The changes in the microstructure and mechanical properties with heat treatment have been correlated with ballistic performance of the steel. Experimental results showed that 200°C tempering gives the best ballistic performance.

Perforation of 5083-H116 Aluminum Armor Plates with Ogive-Nose Rods and 7.62 mm APM2 Bullets

We conducted an experimental and analytical study to understand the mechanisms and dominant parameters for ogive-nose rods and 7.62 mm APM2 bullets that perforate 5083-H116 aluminum armor plates. The 20-mm-diameter, 95-mm-long, ogive-nose, 197 g, hard steel rods were launched with a gas gun to striking velocities between 230–370 m/s. The 7.62-mm-diameter, 10.7 g, APM2 bullet consists of a brass jacket, lead filler, and a 5.25 g, ogive-nose, hard steel core. The brass and lead were stripped from the APM2 bullets by the targets, so we conducted ballistic experiments with both the APM2 bullets and only the hard steel cores. These projectiles were fired from a rifle to striking velocities between 480–950 m/s. Targets were 20, 40, and 60-mm-thick, where the 40 and 60-mm-thick targets were made up of layered 20-mm-thick plates in contact with each other. The measured ballistic-limit velocities for the APM2 bullets were 4, 6, and 12% smaller than that for the hard steel cores for the 20, 40, and 60-mm-thick targets, respectively. Thus, the brass jacket and lead filler had a relatively small effect on the perforation process. In addition, we conducted large strain, compression tests on the 5083-H116 aluminum plate material for input to perforation equations derived from a cavity-expansion model for the ogive-nose rods and steel core projectiles. Predictions for the rod and hard steel core projectiles are shown to be in good agreement with measured ballistic-limit and residual velocity data. These experimental results and perforation equations display the dominant problem parameters.