Ceramic Armors Research Articles

Ballistic performance of monolithic rubber-ceramic composite armor

This work presents the research results regarding the ballistic response characteristics of monolithic ceramic armors. Two different configurations of armors are considered for investigation, aiming at identifying ways to increase the ballistic performance of Small Arms Protective Insert (SAPI). The first configuration consists of a monolithic ceramic tile (Al2O3) with a backing plate made of high-performance Kevlar-29 fiber reinforced composite; the second one has the same design as the first, but the monolithic ceramic tile is covered by a thin rubber layer. The impact behavior of the ceramic composite armors is analyzed numerically, using the finite element method. Some characteristic features, including the ballistic performance and the fracture conoid angle (for the ceramic tile) are discussed. The numerical models developed for the two armor configurations are validated by ballistic tests, where the projectile impact on the armors and the mechanical integrity of the armor systems after impact are observed. The results from simulations and experiments show that the Al2O3/Kevlar 29 composite armor is able to capture a 7.62 mm bullet with a striking velocity of 690 m/s and the rubber-ceramic composite armor is able to capture 5.56 × 45 mm bullet M855 (with an armor piercing tip) with an impact velocity of 894 m/s. It has been found that, when a rubber layer is placed on the front face of a ceramic composite armor, better ballistic performance is achieved. The experiments show that, when a rubber material is impacted by a projectile, its behavior at high velocities and high strain rates changes from elastic to brittle.

Serbest Parçacıklı Zırh Sistemlerinin Balistik Performansının Deneysel Olarak İncelenmesi

Recent armor studies generally rely on improving the single-shot capabilities of ceramic armors. In multi-shot studies, ballistics tests assume that there is a certain distribution, so these successive shots were not made from exact same point. With these shots, thus, the armor completely loses its effectiveness. In this study, the ballistic performance of damaged and undamaged free particle armor system in multiple hits from exact same and different points was experimentally investigated. The new armor system, consisting Al2O3 free ceramic balls, tested with 9 mm FMJ and 7.62 mm API ammunition. This armor system prevented perforation in multi-hits from the same point, and the depth of depression in ballistic clay was 9.42 mm and bullet deviation in trajectory was 27 mm. In the shots with dispersion, depression depth was limited to 3.52 mm and deviation increased with each shot. As a result, it has been found that the free particle armor system performs more ballistic efficiency than conventional armors even in the most challenging conditions. The ceramic balls, being more irregularly and densely spaced with each shot, increase the likelihood of the bullet hitting at larger angles and increase ricochet in direct proportion.

A numerical study on high-velocity impact behaviour of ceramic composite laminates

Currently, silicon carbide (SiC) is of enormous concern because of its high compressive strength,high thermal conductivity, high thermal shock resistance and small coefficient of thermal expansion. SiC has its applicability in armored vehicles, hypersonic armaments, and bullet-resistant armours in the future. The current focus is on understanding the behavior of SiC as used in laminated ceramic armours during the ballistic impact for its profound use in armoured vehicles. To achieve these objectives, computational simulations have been performed for the aforementioned materials using ANSYS/AUTODYN. It was concluded that when SiC was used as a front layer in laminated armours, it significantly increased the strength of the material against the hitting projectiles. The aforementioned composite material was even successful against the sniper gun projectile. The optimized thickness for the given configuration was found to be 41 mm with the consideration of approximately 50% depth of penetration. The modeled configuration was found to be approximately nine times stronger than the conventional laminated armours. The current study was compared with the previous experimental studies and the results were in good agreement. This agreement solely pertains to the pattern observed and not to individual values. It indicated the difference in % age DOP for the present research and previous studies with the increasing thickness of laminated armour. The trend observed was nearly similar to previous experimental studies. This showed that the DOP was reduced, as the thickness increased. Moreover, the previous studies showed that only ALON (aluminium-oxynitride) and sapphire had the required strength to act as a hard front-faced layer in laminated glass, but the current study improvised it to a Silicon carbide hard front-faced layer also.

Advanced manufacturing methods for ceramic and bioinspired ceramic composites: A review

Ceramics and ceramic composites are often utilised for armour applications, where light weight and ballistic protection are essential. Recently, bio-inspired materials and composites for future armour applications are attracting increasing attention from researchers and engineers. In order to choose the suitable methods and techniques to fabricate ceramic and bioinspired ceramic composite armours cost-effectively, it is necessary to understand current techniques for manufacturing ceramic and ceramic composite products. In this paper, we provide a state-of-the-art review of advanced/potential manufacturing techniques available to fabricate ceramic and bioinspired ceramic composites. These methods encompass powder-based techniques (e.g., Selective Laser Melting/Sintering, Binder Jetting) used for prototyping porous ceramic structures, as well as vat polymerisation (e.g., Stereolithography, Digital Light Processing) and Slurry-Based Deposition (e.g., Direct Ink Writing, Fused Deposition Modelling), which are employed for fabricating dense ceramic parts.

Design theory and anti-ballistic effect simulation of dual phase hybrid functionally graded ceramic composite armor

Functional gradient structure design is one way to improve the anti-ballistic performance of ceramic composite armors. In this paper, the design theory of dual phase hybrid functionally graded ceramics is established. Through the finite element simulation of the anti-ballistic behaviour, three structural effects of dual phase hybrid functionally graded ceramics composite armor are studied: monolithic ceramics (MC), unidirectional functionally graded ceramics (UFGC) and bidirectional functionally graded ceramics (BFGC). The ceramics structure of composite armor is optimized. The simulation results of the optimized structure of unidirectional and bidirectional functionally graded ceramics are better than that of monolithic ceramics, and the weight is lighter. This research can provide theoretical support for the design of functionally graded ceramic composite armor.

Multiple ballistic damage of segmented SiC/BN laminated ceramic composite armor

This article investigated the structure of the laminated ceramics to improve the multiple ballistic performance of segmented ceramic composite armors. The multiple ballistic experiments were conducted with 5.8 mm caliber steel core bullets at the impact velocity of about 920 m/s. The experiments verified that two laminated SiC/BN structures (GLC and ULC) exhibit higher residual ballistic performances than the monolithic SiC structure (MC). Moreover, through damage evolution analysis, two laminated SiC/BN structures (GLC and ULC) exhibit less sensitivity to the multiple ballistic impacts damages, and possess more energy absorption mechanisms than the monolithic ceramics. The structure design of the laminated of ceramics is beneficial for improving the multiple ballistic performances of composite armors and reducing the crater deformation.

Performance evaluation of multilayered ceramic composite armors: New design and advanced predictive method

Novel body armors are designed to protect against ballistic threats in the most vulnerable organs within the thorax and abdomen. Decreasing the armor weight without affecting its total integrity after the impact is one of the most challenging tasks. In this study, we combine advanced numerical simulations and experimental tests to investigate the ballistic performance of multilayered armor systems (MAS) consisting of laminated alumina (Al2O3) ceramic plates with multi-curve form and a hybrid composite backing. The ballistic trauma absorption and ceramic fracturing morphology are considered evaluation criteria. The investigation provides enough data on the measured trauma and the results are compared to advanced monolithic ceramics. The ballistic tests showed that bonding three or two ceramic plates with polymeric interlayer decreases considerably the eroded ceramic mass in comparison to monolithic ceramic tiles. Furthermore, the layup of two thin Al2O3tiles with frontal confinement gives the same trauma-weight index as monolithic silicon carbide and reaction-bonded boron carbide plates. The combination of K129 and KM2 aramid weave fabrics decreases the composite backing weight by 33% and increases its ballistic performance in comparison to homogeneous aramid fabrics. Numerical simulations that involve the use of solid Lagrange and adaptive solid/smooth particles hydrodynamics (SPH) numerical approaches with detailed 3D models of the bullet and the MAS are presented in this work. Based on the statistical analysis, a better prediction of the back face deformation and bullet residual length is obtained by the adaptive solid/SPH method, which is found more suitable for the simulation of multilayered armor impact scenarios.

Effect of sphere radius and bullet hitting location on the ballistic performance of alumina ceramic tile

Designers in the defense industry aim to increase the protectiveness of armors while decreasing their weight. On-body armors, composites, and ceramics are widely used due to their lightweight, high hardness, and reduction in blunt trauma. Ceramic armor materials are usually used as the front face for their capability to erode or break up the projectile. There exist various parameters affecting the performance of ceramic armors, and one of these parameters is surface profile. It is a compelling parameter due to its ability to yaw the projectile, causing a reduction of projectile penetration capacity. This study aims to compare alumina ceramic tiles with different surface profiles in terms of their specific kinetic energy absorption (SKEA). Although experimental results are necessary due to an armor system’s acceptance, numerical results lead to a better understanding of surface profiling. In this study, LS-DYNA software is used for ballistic impact simulations to explore the effect of surface profiling. In the simulations, a steel projectile with varying velocities penetrates a ceramic tile. Johnson-Cook material model is used for the projectile, whereas Johnson- Holmquist material model is used for ceramic tiles. For the modeling of ceramic tile, smoothed particle hydrodynamics (SPH) is used to capture fractures and debris. In this study, the finite element (FE) model that simulates a projectile impacting a flat ceramic tile is generated and validated with the experimental results available in the literature. Then, surface profiled ceramic tiles having spherical surface profile with different radius values are analyzed, and their SKEA values are compared. It is found that surface profiling can increase the SKEA value up to 56% when the bullet hits the gap between four spheres. The worst ballistic performance of surface profiled tiles occurs when the bullet hits the top of the sphere; however, even the worst performance increases the SKEA value by 21%.

Research on ceramic fragmentation behavior of lightweight ceramic/metal composite armor during vertical penetration

In order to investigate the ceramic fragmentation behavior of light ceramic composite armors in the process of anti-penetration, ballistic impact tests of ceramic/metal composite armors with different back cover and ceramic thicknesses using a penetrating projectile of 12.7 mm in diameter was carried out. The target was installed in a recycling bin, and the recovery rate of ceramic fragments was above 95%. By observing the macroscopic failure characteristics of the recovered target ceramics, the relationship between different thickness combinations of the ceramics and the main failure characteristics was analyzed. And through the multi-stage screening and weighing of the ceramic fragments, the size distribution law of the ceramic fragments with different thickness combinations was analyzed. The results show that the fracture cone of the ceramic was the main failure characteristic of the ceramic panel, and the macroscopic cracks mainly include radial cracks, ring cracks and conical cracks. The ceramic cone can be subdivided into a crushing zone composed of small powdered ceramic fragments caused by high compressive stress and a broken zone composed of large ceramic fragments caused by stress waves. The size distribution of the ceramic fragments in the ceramic cone after impact satisfies the Rosin-Rammler distribution model. With the increase of the back plate thickness, the half conical angle of the ceramic cone increases, which leads to increases in the overall volume of the ceramic cone and the proportion of the broken zone. The resulting ceramic fragments are mainly large size fragments, and the overall broken size in the ceramic cone increases. When the ceramic thickness increases, the half conical angle and the number of radial cracks remain basically unchanged, the proportion of the crushing zone in the ceramic cone increases, and the overall crushing size decreases.

Characteristics of interface defeat and penetration during the impact between a ceramic armor and a long-rod projectile

Interface defeat/dwell can effectively improve the anti-penetration performance of a ceramic armor at certain degree, which attracts the attention from researchers all over the world in recent years. Experiments on a ceramic armor subjected to the impact of a long-rod projectile (LRP) were carried out to investigate the characteristics of interface defeat and penetration during the impact in this paper. A theoretical model for the penetration process of a LRP into a ceramic target with semi-finite thickness at different impact velocities was established by considering interface defeat/dwell to study quantitatively the effect of interface defeat/dwell on the penetration. The theoretically calculated results on dwell/penetration transition velocity, dwell time, penetration velocity and depth of penetration agree well with the experimental data, which proves that the established theoretical model is accurate. The influences of the projectile and ceramic materials on the interface defeat/dwell and penetration were analyzed. Both the experimental results and the calculated results by the theoretical model show that the interaction between LRPs and ceramics transfers from interface defeat to penetration when the impact velocity increases. It also indicates that the established theoretical model can depict the interaction modes of ceramics and LRPs under different impact velocities. The yield stress and density of the projectile materials play a coupling role in the interaction between LRPs and ceramics when the interface defeat/dwell occurs. The higher the yield strength and density of the projectile materials, the shorter the dwell time and the higher the penetrating ability of the projectile. The higher the dynamical yield strength of the ceramics, the more markedly the interface defeat/dwell and the higher the anti-penetration ability of the ceramic armors. The established theoretical model in consideration of interface defeat/dwell can partially reveal the mechanism of the interface defeat, and it can provide a reference for the design of ceramic composite targets.

An analysis of bi-layer ceramic armor and optimization of protection efficiency

The bi-layer composite ceramic armors are widely used in the protection field, and its design method is keep changing since the Florence model has been found. In this study, an analytical design method of bi-layer was proposed and examined with a new ceramic protection efficiency definition. With this definition, the protection efficiency of composite ceramic armor can be divided into two independent parts: the protection efficiency of ceramic and the protection efficiency of backing plate. By using this analytical design method, the design of the bi-layer ceramic armor can be more efficiency and the material of armor can be selected more accurately.

Non-Destructive X-ray Evaluation and Gap Measurement of Ceramic Armor Plate

Ceramic armors are usually made of a close-fitting periodic array of ceramic tiles, and have gaps between the tiles. The ballistic performance of the ceramic armor is highly affected by the gap width and it is important to find a way to inspect and evaluate it with no destruction. So the gaps of two ceramic armor plates, which were respectively made through hot-press vulcanization machine and autoclave system, were inspected and measured by a non-destructive X-ray evaluation method. But because of the magnification effect of the X-ray method, the measured gap width was not real. So that, it is critical to find the relation between the actual gap width with the measured. Though analysis of the magnification effect of X-ray inspection, we proposed a formula between the two, and calculated the actual gap width of the two different armor plates. It could be concluded that the autoclave method was better, with mean gap width was only 34% of that hot-press vulcanization machine made.

Effects of impact velocity on the dynamic fragmentation of rigid-brittle projectiles and ceramic composite armors

Effects of impact velocity on the dynamic fragmentation of rigid-brittle projectiles and ceramic composite armors

Effect of Cover Plate on the Ballistic Performance of Ceramic Armor.

The interface defeat and dwell can effectively improve the ballistic performance of ceramic armors under high velocity impact of long rod projectiles. Confinement conditions along both axial and radial directions of ceramic armors can affect these behaviors. With the aim of giving an insight into the effect of cover plate thickness and connection mode of cover plates with confining tubes on these behaviors, numerical simulations were performed in which the confined silicon carbide (SiC) targets with cover plates were impacted by tungsten rods. The pressure on the surfaces of SiC targets with fixed cover plates are compared to that with free cover plates, showing that the plates fixed with the confining tubes can produce higher pressure by way of wedging. With the increase in cover plate thickness, the dwell duration of the tungsten rods on the ceramic interface gradually grows. In addition, the upper and lower limits of transition impact velocities for the SiC targets with cover plates in different connection modes (i.e., free or fixed) were obtained and analyzed. The results show that the increase rate of the transition velocity region for the cover plate with the fixed-mode is relatively stable and lower than with the free-mode. On this basis, the fixed cover plate contributes higher ballistic performances to the SiC target than the free cover plate. It is also noteworthy that the size of transition velocity region does not enlarge linearly with the increase in cover plate thickness due to the slow growth of the upper limit. Accordingly, thickness thresholds exist, which are 5 mm and 6 mm for the fixed and free cover plates, respectively. Considering the ballistic performance and economy, the cover plate with the thickness ranging from 3 mm to 5 mm, i.e., 1.5~2.5 times of the tungsten rod diameter, is ideal for the structural dimensions in this paper.

Experiments and simulations of the ballistic response of ceramic composite armors

A lightweight multilayer ceramic composite armor with a sandwich structure back plate was proposed by studying the penetration process, damage mechanism, and the function of each layer of the composite armor against the 12.7 mm armor-piercing projectile. The effectiveness of the simulation was verified by comparing the experimental and simulation data. The effects of crack initiation in the ceramics, abrasion of ceramics, and size of ceramic cones on the penetration resistance of targets were discussed. The structural configuration of backplate sequence and thickness ratio was optimized through finite element simulation on ANSYS/LS-DYNA. Results indicate that boundary constraints have a significant effect on the antipenetration performance of ceramics. The antipenetration performance is the best when the structure of restrained composite armor is Al6061/Al2O3/TC4/Kevlar®/TC4 and the thickness ratio of the TC4 transition and back plates is 4:3.

Effect of Al alloy back panel on the dynamic penetration and damage characteristics of ceramic composite armors

This paper mainly focuses on the investigation of dynamic penetration and damage characteristics of a hybrid ceramic composite armor normally impacted by 12.7 mm armor piercing incendiary projectiles. The hybrid ceramic composite armor was composed of a ceramic cylinder layer, a Ti–6Al–4V plate, an ultrahigh molecular weight polyethylene (UHMWPE) composite layer, and an Al alloy panel. Three different areal densities of composite laminates with 82, 87, and 92 kg/m2 were tested. 3D finite element model of the ceramic composite armor was generated in ABAQUS, and the simulation results were employed to study the damage evolution. The effect of alumina ceramic cylinders layer on the ballistic performance and the failure mechanisms of Ti–6Al–4V and UHMWPE after ballistic impact were examined by experimental and simulative results. According to the numerical and analytical models, an optimal thickness range of Al alloy back panel was found in minimizing areal density of the ceramic composite armor.

Mechanical property and ballistic resistance of graphene platelets/B4C ceramic armor prepared by spark plasma sintering

Boron carbide (B4C) ceramic toughened by graphene platelets (GPLs) was prepared by spark plasma sintering. Nonmetallic sintering aids Al2O3/Y2O3 were used to improve the sintering ability of boron carbide. Impacts of Al2O3/Y2O3 on mechanical properties and microstructure, and toughening mechanisms of graphene platelets were studied. When the content of Al2O3/Y2O3 is 5 wt%, the B4C ceramic was fully densified, and its Vickers harness and fracture toughness are 30.87 ± 0.26 GPa and 5.76 ± 0.37 MPa m1/2, respectively. Fracture toughness of B4C ceramic containing 1.5 wt% GPLs is increased by 23.1% in comparison with that of B4C ceramic without GPLs, which is mainly attributed to the pining effect and packing capacity of GPLs. Ballistic resistance of the GPLs/B4C ceramic armor was experimentally studied with the method of depth of penetration test in contrast to two commercial ceramic armors (SiC, B4C). Compared to SiC and B4C, the penetration depth on the GPLs/B4C ceramic armor is the smallest, and the ballistic resistance of GPLs/B4C ceramic armor is increased by 50% and 12.5%, respectively.

Influence of prestress on ballistic performance of bi-layer ceramic composite armors: Experiments and simulations

The effect of prestress on the ballistic performance of bi-layer ceramic composite armors was explored both experimentally and numerically. Three types of target plate with different prestress levels were prepared using the method of shrink-fit, and tested with ballistic experiments. Residual velocity and length of the projectile were recorded and failure mode of each target was examined. A numerical technique was also proposed to explore the penetration process of projectile and the enhancement mechanism of prestress, with the effectiveness of simulation results validated by experimental measurements. Prestressing the ceramic led to more kinetic energy dissipated by plastic deformation and erosion of the projectile, causing more than 25% increase in ballistic limit. The effects of key geometrical parameters – thickness and diameter of ceramic tile – on ballistic limit were systematically explored, and a critical tile thickness for the influence of prestressing on ballistic performance was identified.

Microscopic wear study of the sintered diamond trepanning drill during machining alumina armor ceramics

High purity engineering ceramics have been increasingly used for constituting novel lightweight ceramic composite armors along with various FRP materials. In the assembly process of ceramic composite armors, a large number of hole processing is required. Usually, diamond trepanning drills are preferentially adopted for machining relatively large holes of engineering ceramics. However, during drilling high purity armor engineering ceramics, the diamond tools are usually worn considerably due to their high dynamic compression strength and high hardness. In this study, taking the high purity alumina armor ceramics (99 wt% Al2O3) as machining object, the comprehensive wear features of the sintered diamond trepanning drill have been intensively studied through SEM examinations, including the microscopic wear morphologies of diamond grains and matrix binding agent, the diamond abrasion mechanism, the wear disfigurations of the drill labial surface and the drill slipping mechanism. According to the discussed results, the wear process of the diamond grains at the matrix labial surface can be divided into three stages: intact crystal, slight wear and severe wear stages. The quicksand phenomenon occurrence around the diamond grains is the typical feature of the matrix binding agent wear. The normal grinding of the drill can be interrupted by the severe inner-trumpet-shape wear and the cutting-groove wear of the drill labial surface. In most situations, only the slight inner-trumpet-shape wear occurs for the drill, which does not affect the normal drilling operation. The drill slipping is mainly attributed to the fact that most exposed diamond grains at the drill labial surface have been rubbed down into a polished planar shape and totally blunted. The results achieved in this study can provide helpful references for the performance improvement design of the sintered diamond trepanning drill.

Effect of the impact geometry in the ballistic trauma absorption of a ceramic multilayered armor system

Ceramic armors are frequently used for protection against high energy projectiles, such as the 7.62mm and 5.56mm. Recently, it has been demonstrated that a modification in the geometry of the impact face, from flat to convex, enlarges the stress distribution zone created by the projectile-target interaction. This effect raises the projectile's energy absorption and might improve the user's safety. In the present work, the objective is to characterize ceramic armor plates with convex impact face, by means of the NIJ-0101.06 (2008) standard methodology, aiming to provide an eventual application in armor vests. The characterization is based on the measurement of the backface signature, a deformation behind armor imprinted in a reference material that simulates the consistency of the human body. The results showed significant improvement in the ballistic performance after the impact geometry modification.