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The terminal ballistics of long-rod penetrators is a very complex field of research involving high pressure physics, continuum mechanics, material science and high strain rate phenomena. The research in this field is advanced through experimental data collection, engineering models, and numerical simulations. In the present paper, we summarize some of our recent work which is focused on determining the important material parameters in the interaction of long rods with various targets (both stationary and moving). Our basic goal is to be able to account for various phenomena encountered in the experiments, rather than reproduce the data very accurately. We achieve this goal by using the minimal set of material parameters which is needed in order to highlight the basic features in the interaction. We also show how 3D numerical simulations help to establish a simple model for the complex interaction between a tungsten alloy rod and a moving steel plate. [Copyright &y& Elsevier]

The ballistic performance, and behaviour, of an armour system is governed by two major sets of variables, geometrical and material. Of these, the consistency of performance, especially against small arms ammunition, will depend upon the consistency of the properties of the constituent materials. In a body armour system for example, fibre diameter, areal density of woven fabric, and bulk density of ceramic are examples of critical parameters and monitoring such parameters will form the backbone of associated quality control procedures. What is often overlooked, because it can fall into the User's domain, are the interfaces that exist between the various products; the carrier, the Soft Armour Insert (SAI), and the one or two hard armour plates (HAP1 and HAP2). This is especially true if the various products are sourced from different suppliers. There are between 30 and 150 individual layers within a typical body armour system, and each of the interfaces between each of those layers will, in some way or another, contribute to the ballistic performance of the system. For example, consider the following interfaces/interlayers: (i) the frictional, sliding, inter-ply surfaces within a soft armour pack, and also between the pack and the carrier, (ii) the air-gaps that may develop within the soft armour pack, (iii) the interconnecting space between the soft armour pack and the hard armour plate, (iv) the nature of the interfaces between adjacent plies of a multiplied backing laminate, even in a highly compressed Ultra High Molecular Weight Polyethylene (UHMWPE) variant, (v) the interlayer between the ceramic and its substrate, within a HAP, and (vi) the geometrical fit between two hard armour plates within a stacked body armour system. This paper will provide a Userfriendly overview of all such interfaces and provide unique guidance as to their criticality and influence. [ABSTRACT FROM AUTHOR]

Production of ceramic armour solutions on-demand/in-theatre would have significant logistical and military advantages. However, even assuming that such technologies could be successfully deployed in the field, such near net-shape manufacturing technology is relatively immature compared to conventional sintering of ceramics. In this study, the ballistic performance of a series of additively manufactured (AM)/rapidly-prototyped (RP) alumina tiles of 97.2% of the density of Sintox FA™ were investigated using both forward- and reverse-ballistic experiments. These experiments, undertaken with compressed gasguns, employed the depth-of-penetration technique and flash X-ray as primary diagnostics to interrogate both efficiency of penetration and projectile-target interaction, respectively. The RP alumina was found to exhibit useful ballistic properties, successfully defeating steel-cored (AP) 7.62 x 39mm BXN rounds at velocities of up-to c.a. 850 m/s, while exhibiting comparable failure modes to conventionally sintered armour-grade Sintox FA™. However, where a <1% by vol. Cu dopant was introduced into the RP material failure modes changed dramatically with performance dropping below that of conventionally sintered alumina. Overall, the results from both sets of experiments were complimentary and clearly indicated the potential of such RP materials to play an active role in provision of real-world body armour solutions provided quality control of the RP material can be maintained. [ABSTRACT FROM AUTHOR]

Production of ceramic armour solutions on-demand/in-theatre would have significant logistical and military advantages. However, even assuming that such technologies could be successfully deployed in the field, such near net-shape manufacturing technology is relatively immature compared to conventional sintering of ceramics. In this study, the ballistic performance of a series of additively manufactured (AM)/rapidly-prototyped (RP) alumina tiles of 97.2% of the density of Sintox FA™ were investigated using both forward- and reverse-ballistic experiments. These experiments, undertaken with compressed gas-guns, employed the depth-of-penetration technique and flash X-ray as primary diagnostics to interrogate both efficiency of penetration and projectile-target interaction, respectively. The RP alumina was found to exhibit useful ballistic properties, successfully defeating steel-cored (AP) 7.62 × 39 mm BXN rounds at velocities of up-to c.a. 850 m/s, while exhibiting comparable failure modes to conventionally sintered armour-grade Sintox FA™. However, where a

In this paper in order to try and elucidate the effects of particle morphology on ballistic response of comminuted systems, a series of experiments were carried out via the use of powder compacts with differing initial particle morphologies. This approach provided a route to readily manufacture comminuted armour analogues with significantly different microstructural compositions. In this study pre-formed ‘fragmented-ceramic’ analogues were cold-pressed using plasma-spray alumina powders with two differing initial morphologies (angular and spherical). These compacts were then impacted using 7.62 mm FFV AP (Förenade Fabriksverken Armour Piercing) rounds with the subsequent depth-of-penetration of the impacting projectile into backing Al 6082 blocks used to provide a measure of pressed ceramic ballistic response. When material areal density was accounted for via differing ballistic efficiency calculations a strong indication of particle morphology influence on post-impact ceramic properties was apparent. These results were reinforced by a separate small series of plate-impact experiments, whose results indicated that powder morphology had a strong influence on the nature of compact collapse. [ABSTRACT FROM AUTHOR]

The ballistic capabilities of composite metal foam (CMF) armors were experimentally tested against a 14.5 × 114 mm B32 armor-piercing incendiary (API) and compared to various sizes of armor-piercing (AP) ballistic threats, ranging from a 7.62 to 12.7 mm. Three different arrangements of layered hard armors were designed and manufactured using ceramic faceplates (in one layer, two layers or multiple tiles), a combination of ceramic and steel face sheets, with a single-layered CMF core, and a thin aluminum backing. The performance of various CMF armor designs against the 14.5 mm rounds are compared to each other and to the performance of the rolled homogeneous armor standard to identify the most efficient design for further investigations. The percentage of kinetic energy absorbed by the CMF layer in various armor arrangements and in tests against various threat sizes was calculated and compared. It appears that the larger the threat size, the more efficient the CMF layer will be due to a greater number of hollow metal spheres that are engaged in absorbing the impact energy. The results from this study will help to model and predict the performance of CMF armors against various threat sizes and impact energies. [ABSTRACT FROM AUTHOR]

The performance of 7.62×54r BS32 armour-piercing incendiary (API) projectiles against ceramic-faced armour is investigated in trials for yawed impacts. Controlled yaw of the projectile was induced by chamfering the rear of the projectile, producing strong asymmetric lift forces on the tail of the round during the intermediate ballistics phase. High-speed video recorded yaw in two orthogonal planes immediately before impact. Projectile yaw varied in a sinusoidal manner at approximately 3.5m wavelength with a maximum of 8-14° at approximately 10m from the muzzle. Logistic regression was used to determine the penetration probability curve and V50 ballistic limit velocity which was found to be 735 ms-1 for the un-yawed projectiles but only 685 ms-1 for the yawed projectiles. [ABSTRACT FROM AUTHOR]

This article is a brief study conducted on adhesives currently used for manufacturing performance ballistic protection structures. The study landmarks several aspects, such as: types of connections available to achieve multilayer structures based on ceramics, metals and polymers; ways in which adhesives influence the ballistic performance of protective structures; analysis of various types of adhesives used in ballistic protection industry; general considerations in the selection of adhesives for certain types of armor and protective structures; considerations for characterizing, testing and modeling adhesives [ABSTRACT FROM AUTHOR]

The development of ballistic protective equipment is marked by constant improvement of the performance and the level of protection while reducing the weight of the ballistic protection structures and individual armor. Generally, the protective systems are designed and implemented by the optimum combination of different types of materials, such as ceramics, metals, polymers, fibers and composite materials, in order to meet the specific requirements of the various types of threats. Thus, the ballistic protection is achieved by material layers with specific functions. Considering these aspects, research nowadays focuses on implementing simpler structures in terms of construction, enabling high mobility while keeping the same performance level or even a higher level of protection than previous generations. This article briefly presents some of the basic materials for one of the future solutions, the "liquid body armor". [ABSTRACT FROM AUTHOR]

Abstract: Laboratory-made Al2O3 and spinel ceramics were investigated so as to enable ballistic tests with a variation of individual influences while keeping other factors constant. The study was aimed at answering the question about influences of different microstructures and of basic mechanical properties and included also a systematic investigation of the effects of backing materials. Contradictive findings of the past are explained by the observation that the ballistic impact stability of ceramics and single crystals with different backings (steel, aluminum, glass) is governed by a strict hierarchy of few major influences: (1) Top priority is the mode of ceramic fragmentation governed by microstructural features and by the dynamic stiffness of the ceramic/backing target; these influences also affect the relative importance of dwell and penetration. (2a) On a lower rank, Young’s modulus of the ceramic is responsible for projectile damage during dwell but the importance of this influence depends on the priority of ceramic fragmentation. (2b) On penetration, the abrasive benefit of a high ceramic hardness depends on the size of the ceramic debris, i.e. on priority (1). In contrast, all average strength data are weakly correlated with the ballistic efficiency. [Copyright &y& Elsevier]

Abstract: This paper was prepared in response to being awarded the Hypervelocity Impact Society''s Distinguished Scientist Award at HVIS 2003 held in Noordwijk, The Netherlands. It is traditional that the paper associated with the HVIS Distinguished Scientist Award is a retrospective on the recipient''s career. This paper is in that tradition. [Copyright &y& Elsevier]

Abstract: This paper presents a semi-analytical approach on the performance of ceramic/metal armor under ballistic impact. Numerical simulations for alumina/aluminum armor impacted by 20 mm APDS in AUTODYN were carried out and verified against the experimental data. Comprehensive numerical simulations were performed using the verified numerical model material parameters providing corroborative data for ensuing discussions. A semi-analytical model relating projectile residual velocity, impact velocity and armor ballistic limit velocity (BLV) is presented for impact of hard projectile against ceramic/metal armor. It is shown that the projectile residual velocity and BLV satisfy the replica scaling laws. Based on the replica scaling laws of projectile residual velocity and BLV, an empirical equation for BLV is obtained and used for armor optimization applications giving reasonable results similar to experiments available in the literature. [Copyright &y& Elsevier]

In order to explore the bullet proof mechanism of ceramic/steel composite armor, the ballistic impact experiment was carried out to study the dynamic response of ceramic/steel composite armor subjected to the impact of high speed fragments. The damages of projectile, ceramic and steel back plate were described physically and analyzed phenomenologically. The damage modes of ceramic and steel back plate were determined. The energy transformation during the ballistic penetration and the bullet proof performance of the ceramic/ship steel composite armor were analyzed. The results show that the conical crash is a main damage mode of ceramic under the impact of high speed fragments. And the main macro cracks are radial, ring and conical cracks which extend outward at about 65° angle included between the conical crack and the initial surface normal. Besides there are the inverse conical cracks extended outward at angle of 65° to the back surface normal. The deformation range, destructiveness and damage mode of the back plate have great different from those of ship steel target. The deformation mode of the backing plate is bulging-dishing when the impact velocity is below the ballistic limit. When the impact velocity exceeds the ballistic limit, the back plate has 3 damage modes, i. e. shearing damage, dishing-shearing-petaloid damage and dishing-petaloid damage, as the relative thickness of ceramic increases. In the penetration process of light ceramic/metal composite armor, the kinetic energy of projectile is mainly dissipated in the deformation and damage of projectile and back plate. When the velocity of the penetrator is about ballistic limit, the energy dissipated in projectile and back plate damages varies with the relative thickness of ceramic. But the total energy dissipated in these facets occupies more than 90% of initial kinetic energy of the projectile, and the energy dissipated in the fragmentation of ceramic and the ejecting kinetic energy of ceramic fragments occupies less than 10% of its initial kinetic energy. [ABSTRACT FROM AUTHOR]

Abstract: The effect of rubber, Teflon and aluminum foam interlayer material on the ballistic performance of composite armor was investigated both experimentally and numerically. Although, rubber interlayer did not cause any significant delay in the initial stress build-up in the composite layer, Teflon and aluminum foam interlayer caused a significant delay and reduction in the magnitude of the stress transmitted to the composite backing plate. Damage in the ceramic layer was found to be highly localized around the projectile impact zone for the configuration without interlayer and rubber interlayer while aluminum foam and Teflon interlayer spread the damage zone in the radial direction. Relatively large pieces of the ceramic around the impact axis in the rubber interlayer configuration were observed while the ceramic layer was efficiently fragmented in aluminum foam and Teflon interlayer configuration. [Copyright &y& Elsevier]

The development of lightweight armour systems for ballistic protection is under continuing attention of the manufacturers and users. A new design of the composite armour systems has been developed and ballistically tested. A new armour system consists of a ceramic plate, an intermediate ceramic–polymer layer and a polymer fibre lining as a backing material. The proposed composite armour systems prepared with a use of specially selected compositions of the intermediate layer promoting the absorption of the kinetic energy of projectiles provide adequate ballistic protection to National Institute of Justice (NIJ) level III and level IV, and they successfully withstand multiple hits. [ABSTRACT FROM AUTHOR]

The subject of this paper is to analyze the impact of projectiles against ceramic/metal armour using a simple one-dimensional mode. The model allows the calculation of the loss of projectile mass and its velocity, and gives the deflection of the backup material. This work also investigates the influence of grain size of the ceramic material on ballistic performance, which is very useful during selection of the best material for each application. Therefore, two formulations of the same ceramic material were produced. They had the same chemical composition, the same mechanical properties, but different grain size. The ballistic performances were compared measuring the maximum velocity each formulation was able to support, without perforation. [Copyright &y& Elsevier]

Principles of dimensional analysis are applied in a new interpretation of penetration of ceramic targets subjected to hypervelocity impact. The analysis results in a power series representation – in terms of inverse velocity – of normalized depth of penetration that reduces to the hydrodynamic solution at high impact velocities. Specifically considered are test data from four literature sources involving penetration of confined thick ceramic targets by tungsten long rod projectiles. The ceramics are AD-995 alumina, aluminum nitride, silicon carbide, and boron carbide. Test data can be accurately represented by the linear form of the power series, whereby the same value of a single fitting parameter applies remarkably well for all four ceramics. Comparison of the present model with others in the literature (e.g., Tate's theory) demonstrates a target resistance stress that depends on impact velocity, linearly in the limiting case. Comparison of the present analysis with recent research involving penetration of thin ceramic tiles at lower typical impact velocities confirms the importance of target properties related to fracture and shear strength at the Hugoniot Elastic Limit (HEL) only in the latter. In contrast, in the former (i.e., hypervelocity and thick target) experiments, the current analysis demonstrates dominant dependence of penetration depth only by target mass density. Such comparisons suggest transitions from microstructure-controlled to density-controlled penetration resistance with increasing impact velocity and ceramic target thickness.

Analytical formulas for calculating the maximum velocity of penetration of doublelayer cermet and ceramic/organic-plastic targets are obtained taking into account the structural characteristics of the target and the physical and mechanical properties of the projectile and target materials. Using these formulas, the ballistic resistance of targets was studied and the possibility of optimizing their structure was shown. The results agree qualitatively with available experimental data. The optimal relative thickness of the ceramic layer which provides maximum penetration velocity was determined at areal densities of the target of 30-50 kg/m for different substrate materials. It is found that these velocity values depend weakly on the areal density of the target and are mainly determined by the properties of the substrate material. [ABSTRACT FROM AUTHOR]

Protective shields are used to protect the technical devices from the impacts of high-speed objects, for example, the space systems from orbital garbage. This problem is so important that special spacecrafts are designed to clean up the trash. Ceramic-polymer composite panels have some advantages. However, the characteristics of such panel components have not been studied sufficiently yet. The finite element analysis is an efficient method for the composite characteristics improvement. Obviously, such improvement necessitates searching for a rich variety of composites characteristic. Each option requires creating a brick elements mesh. Adequate FE models have to be developed for penetrators (metal cones, for example) as well as for panels. Voxel based micro modeling makes it possible to develop a composite structure parametrical model. Further on, it is easy to transform this model to FE one. Developing a material model is an important problem of the impact simulation. To study the ceramic-polymer composite behavior using a traditional Johnson-Holmquist model and the most recent Toughened Adhesive Polymer model is suggested. The calculations using LS-DYNA give initial adequate results for impact modeling and thus the suggested approaches of geometrical and of FE modeling are rather effective. [ABSTRACT FROM AUTHOR]

For a ceramic armour impacted by a long rod projectile, increasing the dwell-to-penetration transition velocity significantly improves its ballistic performance, whereas it can be achieved by prestressing of the ceramic or placing a buffer over the impact surface. In this paper, numerical simulation using the AUTODYN hydrocode is conducted to investigate how dwell-to-penetration transition is affected by the radial prestress and the presence of a buffer. Taking account of the pressure-dependent strength of SiC ceramics, it is found that distribution of hydrostatic pressure and equivalent stress in the ceramics controls damage initiation and dwell-to-penetration transition. Ceramic damage initiates from the edge of the projectile and then forms a damaged zone in front of the projectile. Compared to the radial prestress, the buffer more effectively suppresses damage initiation to fulfil interface dwell at a higher transition velocity. [ABSTRACT FROM AUTHOR]

The paper deals with possibilities in improving features of materials used for special equipment through irradiation by accelerated electrons. It relates with a possibility to improve mechanical features of ballistic materials used for a ballistic protection of an individual. At present time there are mainly materials of Kevlar type and ceramics. Their features, e.g. mechanical properties as well may change through irradiation of these materials with accelerated electrons. [1]. So in a practical application it would be possible to improve a ballistic protection of a bullet-proof vest as well as to decrease a weight of a vest meanwhile keeping the protection class.. The achieved results that are presented in the paper can be used also in other applications, e.g. protective clothes used in industry [2]. [ABSTRACT FROM AUTHOR]

In this paper, the behavior of multi-layered Alumina ceramic armor against high velocity projectile has been considered and conoid failure of multi-layered ceramic-epoxy armor has been simulated by means of Johnson & Holmquist constitutive relation in LS-Dyna software. As a result, the conoid failure of top layer ceramic causes the impact pressure to decrease in back layer, and consequently the epoxy interface transfers the pressure distribution between ceramic layers, causing growth and propagation of conoid failure thus distributing the pressure in a larger area, finally resisting against projectile penetration in the armor. Simulation results illustrate that by choosing the proper minimum and maximum thickness of ceramic layers and proper layering of them with thin layers on top backed by thick ceramic layers, higher ballistic performance will be available in designed armors and generally an armor with layered configuration will have higher ballistic resistance than monolithic ceramic tile with/without backing. According to the results, bi-layer ceramic armor with 25% lesser thickness with no backing in comparison with monolithic ceramic layer with backing causes 14% more erosion and 18% less penetration of projectile. [ABSTRACT FROM AUTHOR]

Development of lightweight armors is vital in order to provide ballistic protection in a more effective way. The weight of steel armor can be decreased significantly by setting a front ceramic layer on it. In this paper, the influence of utilizing SiC and Al2O3 ceramic front layer on the ballistic behavior of 4140 bainitic steel was investigated experimentally. All steel plates were initially subjected to the austempering treatment by applying the austenitization at 860 °C for 1 h and then holding in a salt bath at 343 °C for 50 min to get fully bainitic microstructure. And then, the laminated composites, consisting of SiC or Al2O3 front layer (50 × 50 mm in size) and bainitic steel backing layer, were prepared by joining these layers with an acrylic adhesive. After the mechanical and microstructural characterization of the bainitic steel, the ballistic shots were made using 7.62 × 51 mm AP projectile with an average speed of 788.4 m/s on both monolithic steel and layered armor samples for comparison. The samples, which stopped the bullet at normal impact condition without complete perforation or disintegration of the bainitic steel layer, were termed as successful. The bainitic steel achieved the ballistic protection at a thickness ≥ 14 mm but the use of SiC layer provided the weight saving of at least 42.9% and the Al2O3 front layer enabled the weight reduction of 28.6% in the armor with respect to the monolithic 4140 bainitic steel. [ABSTRACT FROM AUTHOR]

In this paper, the behavior of multi-layered ceramic armor and ceramic armor with ductile backing against armor piercing APM2 projectile has been considered numerically. Multi-layered armors in accordance with BR7 ballistic protection class should protect against AP 7.62-mm projectiles with impact velocity of 830m/s. Results show that unlike high strength steel, ceramic resists the initial penetration of brass jacket and lead filler, and, consequently, erodes them at initial stages. This enables higher resistance in ceramic armor with similar mass in comparison with the steel one. It is shown that ceramic armor with ductile backing besides the above characteristics has the capability of bullet jacket strip and capturing brass jacket while the core penetrates through the armor. This characteristic is not observed in multi-layered ceramic armor without the backing plate. Ceramic armor with backing plate reduces a projectile's exit velocity one ninth the residual velocity of multi-layered ceramic armor and one nineteenth the residual velocity of high strength steel armor with similar mass. Another point discussed in this paper is the effective ceramic mass resistance against the projectile. The more mass involved, the more ballistic resistance gained. [ABSTRACT FROM AUTHOR]

Contrary to the moderate ballistic advantage of Al2 O3 ceramics over MgAl2 O4 polycrystals, the present study shows a reverse ratio of the ballistic strength of alumina and spinel single crystals: Spinel single crystals outperform sapphire and exhibit a similarly high stability as submicrometer Al2 O3 ceramics. The results correlate with different cleavage of single crystalline spinel and sapphire, changing the fragmentation on ballistic impact. [ABSTRACT FROM AUTHOR]

Abstract: Porous-ceramic, thermal protection systems were used heavily on the Orbiter, and they are currently being used on the next generation of US manned spacecraft, Orion. These systems insulate reentry critical components of a spacecraft against the intense thermal environments of atmospheric reentry. Additionally, these materials are highly exposed to space environment hazards like solid particle impacts. This paper discusses impact studies up to 10km/s on nominally 8 lb/ft3 alumina-fiber-enhanced-thermal-barrier (AETB8) tiles coated with a toughened-unipiece-fibrous-insulation/reaction-cured-glass layer (TUFI/RCG). A first principles impact model that describes projectile dispersion is described that provides excellent agreement with observations over a broad range of impact velocities, obliquities and projectile materials. [Copyright &y& Elsevier]

The article demonstrates the importance of modeling tools in advancing ceramic transparent armor materials to fielded applications. It discusses the effect of various shape defects on the failure of the transparent materials. Low cost glass is the dominant materials technology used for ballistic transparency protection of armored tactical platforms. The development of next generation ceramics is key to providing enhanced protection capability for future armored windows.

The article discusses a study which examined the silicon carbide (SiC) variants, Saint Gobain Hexoloy and BAE Systems SiC-N, using instrumented Hertzian indentation to compare their damage responses to large localized stresses. Spherical diamond indenters were used to explore a quasi-plastic mode response and brittle mode response in the ceramics. Hot-pressed SiC are effective against a range of ballistic threats. The importance of characterizing and quantifying the differences in mechanical properties and damage behavior is cited.

The article discusses the use of X-ray computed tomography (XCT) in evaluating ballistically-induced damage in ceramic targets. XCT is a non-destructive evaluation technique for revealing the spatial distribution of damage in ceramics. The size of the specimens and the parameters of the XCT approach affect the level of detection and resolution of damage. Several types of damage features were found in the AD995 alumina and silicon carbide targets.

The article discusses the use of ceramics in personnel armor. Sintered alumina and hot pressed boron carbide were primarily used as the ceramics of choice for armor. Continued improvement of armor ceramic performance will be required in the evolution of ballistic threats on the battlefield. The relationship of material properties to performance in armor applications is examined.

The article identifies further potential impact damage diagnostic developments and their technical challenges for improved capabilities and effective application with damage-based ballistic computational modeling. Some of the unique and substantial capabilities that have already been demonstrated include three dimensional (3D) rendering of high resolution virtual solid object target reconstructions and non-invasive volumetric digitization of both metallic and ceramic impacted terminal ballistic targets.

The kinetics of penetration of deformable striking rods into SiC ceramics with different void content is studied. The penetration may be viewed as a two-stage process. At the first stage, the penetration rate is minimal and the rate of contraction of the rod is maximal. At this stage, the penetration resistance of the ceramic is the highest. At the second (quasi-steady-state) stage, the penetration kinetics is similar to the kinetics of penetration into a zero-strength medium and resistance to penetration is largely inertial. At the first stage, the penetration resistance is shown to correlate with the hardness of the ceramic and depend strongly on the void content. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Structural alumina ceramics used in ballistic armour and wear applications with varying alumina contents and manufactured using both slip casting and dry pressing techniques, have been investigated and characterized in terms of their hardness, elastic modulus, fracture toughness, and microstructural characteristics. For a given alumina content, fracture toughness decreases with increasing hardness. Dry pressed samples show slightly higher hardness, and lower fracture toughness for the same alumina content. The hardness, elastic modulus and fracture toughness are higher for the 98% alumina samples while the differences between the lower alumina samples (95 and 91%) are negligible. The grain sizes are bimodal with the majority ≤3 μm and the size range narrows with decreasing alumina content. The microstructures are composed of a matrix phase, corundum (α-Al2O3), grain boundary phases consisting of a glassy phase with varying Al2O3, SiO2, and CaO contents, a crystalline phase, triclinic anorthite (CaAl2Si2O8), and an additional phase, spinel (MgAl2O4), in the lower alumina samples. The proportion of the boundary phase increases with decreasing alumina content and no effect of fabrication method is observed. [ABSTRACT FROM AUTHOR]

Finite element analysis of the impact of 7.62AP bullets on ceramic/aluminum bi-layer hybrids was carried out using AUTODYN hydrocode. Johnson–Cook material model was used for the metal and Johnson–Holmquist model was used for the ceramic. The models were validated with experiments conducted on Al 2 O 3 /Al 5083 and AlN/Al 5083 bi-layer composites. It has been observed that AlN ceramics has superior performance in defeating the bullet in comparison to Al 2 O 3 ceramics. Deformation of the backing plate and the corresponding plastic strain energies are considered in this study for the parameters of performance. The results will enable the design of materials for developing an efficient structure for the protection against the impact of 7.62AP bullets at ordnance velocities. [ABSTRACT FROM AUTHOR]

Abstract: Recent experimental measurements show that eroding long-rod penetration velocity is a linear function of impact velocity over a very wide range of impact velocities and for an interesting range of rod–target material combinations. These experiments all show that U=a+bV, where U and V are the penetration and impact velocity, respectively, and “a” and “b” are constants for given projectile and target materials. Numerical simulations also show that U=a+bV. The accumulation of these results suggests that a linear relationship between penetration and impact velocity may be fundamental over a very large range of impact velocities. A linear relationship between penetration and impact velocity has a number of implications. Some implications of this result for the Tate–Alekseevskii model are briefly examined in this paper. [Copyright &y& Elsevier]

Abstract: An experimental study has been carried out on the ballistic performance of 95% and 99.5% alumina ceramic tiles backed by metal plates, when subjected to normal impact of hard steel 12.7mm armour piercing (AP) projectiles at velocities ranging from 500 to 830ms−1. Typical damaged targets and broken projectiles are presented. The depth of penetration is measured in all the experiments, and the ballistic efficiency factor of the ceramic plates are determined. Results show that the efficiency factor increases with increase in projectile velocity. With the increase in thickness of the ceramic tile, the ballistic efficiency factor for a given velocity is observed to decrease in the case of 99.5% grade and increase in the case of 95% grade ceramic. The higher purity alumina (99.5%) shows higher ballistic performance when compared with the 95% alumina. The 99.5% alumina exhibited a predominantly transcrystalline fracture while the 95% alumina showed a less defined fracture surface. Experiments on 7.62mm AP shots were also done keeping the () ratio same as in 12.7mm AP experiments and results are presented. [Copyright &y& Elsevier]

This article presents computed results for the responses of ceramic targets, with and without prestress, subjected to projectile impact. Also presented is a computational technique to include prestress. Thin and thick ceramic target configurations are used to understand the effect prestressing has on ballistic performance. For both targets two prestress levels (small and large), and two prestress states (radial and hydrostatic) are investigated. The small prestress is similar in magnitude to values obtained experimentally and the large prestress is approximately the maximum prestress the confinement can produce (determined computationally). The targets are subjected to projectile impact and the resulting ballistic responses are evaluated. In all cases prestressing the ceramic enhanced the ballistic performance, although the effect of the different prestress conditions on the ballistic response was not always obvious. [Copyright &y& Elsevier]

This work aims to improve the penetration ability of a 14.5 mm standard armor-piercing projectile into ceramic/armor steel (Al2O3/RHA) composite armor. To this end, ZrO2 toughened Al2O3(ZTA) is prepared as the material for bullet tips, utilizing in situ solidification injection molding that is realized via ceramic dispersant hydrolytic degradation. The penetration power of ZTA ceramic composite projectile, compared with standard armor, against 15 mm armor steel (RHA) and 30 mm Al2O3/RHA composite armor, is studied by ballistics testing combined with numerical simulation. The Tate theory is optimized and then employed to calculate the penetration depth and bullet core's residual mass when ZTA ceramic composite projectile penetrates into Al2O3/RHA composite armor. The results show that when penetrating RHA of 15 mm, the penetration area of ZTA ceramic composite projectile into RHA increases by 27.59% and the exit area by 42.93%. While the standard projectile fails to penetrate the 30 mm Al2O3/RHA composite armor, the ZTA ceramic composite armor-piercing projectile succeeds, with the mass loss reduced by 66.67% over the standard one. The ZTA ceramic composite bullet has a better performance than the standard bullet in penetrating RHA and Al2O3/RHA composite armors. The test results, simulation, and theoretical analysis are consistent. This study has practical values for engineering applications to design new ceramic composite bullets. [ABSTRACT FROM AUTHOR]

Ceramic Matrix Composites (CMCs) have many interesting properties, mainly light weight, cost efficiency, low density, high compressive strength, high hardness and durability. Hence, they emerged as a boon to the development of personnel armors in the past. The current work aims to review various new methodologies adapted for the reinforcement of Alumina (Al 2 O 3) CMCs in recent times, including some of the interesting results obtained with respect to mechanical properties, suitability of the synthesized composites for armor applications, and the upcoming reinforcement trends. Finally, studies related to reinforcement in Al 2 O 3 CMCs, specifically towards armor applications have been consolidated to arrive at some of the important inferences for concluding reasonably. [ABSTRACT FROM AUTHOR]