Armor Systems Research Articles

Optimization of soft armor: the response of homogenous and hybrid multi-ply para-aramid and ultra-high molecular weight polyethylene fabrics under ballistic impact

This research investigated the ballistic response of homogenous and hybrid multi-ply fabrics toward developing a full-scale hybridized soft armor system. Fabrics with varying yarn and thread counts were manufactured from para-aramid and ultra-high molecular weight polyethylene yarns through a plain-woven architecture. Homogeneous fabrics used the same yarn and thread count for two- and three-ply systems. For hybrid systems, two- and three-ply stacks were assembled in various sequences including increasing and decreasing cover factor ( Cfab) and varying yarn types as the strike face and rear face. Ballistic impact testing was performed on all fabrics at low (340 m s−1) and high velocity (620 m s−1). Observations and measurements were performed to determine failure mechanisms, energy absorption, transverse wave propagation, and system effects of multi-ply systems. Hybrid systems showed significant differences in specific energy absorbed (SEA), dependent on the layer order. The para-aramid hybrid systems impacted at 340 m·s−1 showed a significantly greater SEA when the fabrics were ordered with an increasing rather than a decreasing cover factor. At 620 m·s−1 the difference in SEA was less pronounced or absent entirely. It was concluded that hybridization would enhance the performance of a soft armor system and was likely to be most effective for the rear layers of the system where fabrics with a progressively increasing cover factor that were manufactured of fine (550 dTex) para-aramid yarns would offer an advantage. The front layers of the system, subjected to higher strain loading, would benefit from low cover factor fabrics (0.76), which maximize the dissipation of strain from the point of impact.

Thermal Behavior of Curaua-Aramid Hybrid Laminated Composites for Ballistic Helmet.

Hybrid composites are expanding applications in cutting-edge technology industries, which need materials capable of meeting combined properties in order to guarantee high performance and cost-effectiveness. This original article aimed for the first time to investigate the hybrid laminated composite thermal behavior, made of two types of fibers: synthetic Twaron® fabric and natural curaua non-woven mat, reinforcing epoxy matrix. The composite processing was based on the ballistic helmets methodology from the North American Personal Armor System for Ground Troops, currently used by the Brazilian Army, aiming at reduced costs, total weight, and environmental impact associated with the material without compromising ballistic performance. Thermal properties of plain epoxy, aramid fabric, and curaua mat were evaluated, as well as the other five configurations of hybrid laminated composites. These properties were compared using thermogravimetric analysis (TGA) with its derivative (DTG), differential thermal analysis (DTA), and thermomechanical analysis (TMA). The results showed that the plain epoxy begins thermal degradation at 208 °C while the curaua mat at 231 °C and the aramid fabric at 477 °C. The hybrid laminated composites curves showed two or three inflections in terms of mass loss. The only sample that underwent thermal expansion was the five-aramid and three-curaua layers composite. In the third analyzed temperature interval, related to the glass transition temperature of the composites, there was, in general, an increasing thermal stability behavior.

Numerical Study on Free Particle Reinforced Fiber-Metal Composite Sandwiches Under Ballistic Loads

In this study, the ballistic performances of the fiber-metal composite plate with foam core sandwich embedded free particles were numerically investigated. Structures that can change the direction of incoming ammunition in armor designs have always been interesting. Ballistic analyzes of the structures designed with this motivation were carried out with fragment simulated projectile (FSP) under 3 different velocities. The 3D finite element and damage models of the materials were modeled separately, and the analyzes were completed by overcoming the problems encountered in the analysis of the complex structure. The material models of armor system were explained in detail as carbon fiber/epoxy composite plate, aliminum metal plate, PVC foam core material, steel spherical particle and steel fragment simulated projectile. The ballistic behaviors of 2 different types of structures formed according to particle diameter were investigated numerically and the full perforation behavior of the structure formed with small diameter particles was better.

Ballistic performance of optimised light weight composite armour

This research paper presents a comprehensive investigation into the response of a 3D finite element model when subjected to 7.62 AP projectiles. The study utilises Hetherington's armour composite equation and incorporates the Johnson-Holmquist material model to analyse the strength and failure criteria of the ceramic and Kevlar/epoxy components, respectively. The results highlight the remarkable resilience of the composite armour, demonstrating its ability to withstand projectile velocities up to 1500 m/s. However, as the ballistic velocity limit increases, the armour experiences significant damage, including projectile erosion and panel delamination. Through numerical simulations and advanced modelling techniques, the paper thoroughly explores the failure modes and energy absorption characteristics of composite armour systems under projectile impact. It investigates key parameters such as velocity, acceleration, kinetic energy, internal energy, pressure distribution, displacement, and damage progression. The analysis reveals a progressive decrease in kinetic energy as the projectile interacts with the armour, underscoring the crucial role of energy absorption in preventing projectile penetration. Moreover, the impact velocity influences the distribution of internal energy within the composite armour, with higher velocities leading to greater energy absorption up to a threshold limit. The study also determines the ballistic limit velocity (V50) using the velocity history approach and validates the findings with existing literature. Overall, the research provides valuable insights into the limitations of composite armour and offers important recommendations for designing and improving materials to achieve superior ballistic protection. It emphasises the significance of reaching the maximum ballistic limit while maintaining a lightweight armour structure by optimising the total armour thickness. This study contributes to the advancement of armour technology and enhances our understanding of the behaviour of composite materials under high-velocity impacts. It offers valuable guidance for the development of more robust armour systems suitable for various defence and protection applications.

Influence of surface preparation and polymer backing properties on the quasi-static and impact response of ceramic faced 1D armour systems

Ballistic impact is a highly complex environment, the understanding of which is compounded by the advanced materials used for ceramic-polymer composite armours. In this study, the influence of surface preparation and polymer backing properties on the energy absorptive capabilities and ballistic performance of simplified model armours was approached via a methodical investigation using simplified materials and geometries. Quasi-1D (beam) specimens consisting of polyurethane-backed alumina were loaded under three-point bend quasi-statically and at impact speeds. The specimen geometries allowed for the fracture pathways to be observed. To produce the specimens, two polyurethanes with different glass transition temperatures were cured onto alumina strips, eliminating the requirement for a dedicated adhesive and thus simplifying the interfacial dynamics. Further modifications were made by applying a primer surface treatment, by using unbonded polyurethane and adhered polyurethane, and by replacing the polyurethane with glass-reinforced polycarbonate. The beam specimens were loaded quasi-statically at 0.05 mm s-1 at ambient and sub-ambient temperatures, and at 50–300 m s-1 at ambient temperatures. The quasi-static specimens were found to fail by one of two failure modes with approximately a 3x energy absorption difference; the failure was highly dependant upon the interface and polymer characteristics. Under impact, a significant proportion of the energy absorption was provided by the kinetic energy of the fragments. Although, the polymer backing and interfacial properties were found to influence fracture paths during loading. FEA simulations were used to model the behaviours using characterisation data from a previous study; these were found to predict the experimental response well.

Effect of projectile’s nose shape on ballistic performance of ceramic/composite armour: A numerical study

In the present study, finite element analysis were carried out to investigate the ballistic performance of Al2O3-Kevlar 29/epoxy armour system impacted by a 4340 steel projectile. The perforation capacity of a 10 mm thick target was studied against a blunt, ogive, and conical shaped projectile with a fixed diameter and mass of 7.56 mm and 10.7 gm, respectively. The simulations were carried out in Ansys/Autodyn by considering the projectile as a deformable body. The variation of the ballistic limit velocity (BLV) and energy, progressive damage of the target, and projectile deformation were studied comprehensively. It was found that the nose configuration of the projectile significantly influence the target’s ballistic performance. The perforation capacity of the blunt projectile was lower than the ogive and conical shape in all the velocity regimes. At higher impact velocity ( Vi >600 m/s), the target’s resistance was better against the ogive projectile than that of the sharp conical projectile. Interestingly, this phenomenon got reversed when the incident velocity nears the ballistic limit. Also, from the simulation results, it has been possible to obtain the optimum thicknesses of the components for a given total thickness of the armour.

Ballistic performance of functionally graded B4C/Al composites without abrupt interfaces: experiments and simulations

Functionally graded materials (FGMs) are promising protective structures for lightweight armor plates because of their features and designability. However, traditional discretely layered FGMs with macroscopic interfaces can generate unfavorable interlaminar stresses under ballistic attacks, eventually leading to delamination or interlayer tearing. Herein, we constructed new B4C/2024Al FGMs without sharp interfaces between layers. The FGM armor systems with varying through-the-thickness distributions were tested against 7.62 mm armor-piercing incendiary projectiles. The effects of compositional gradient exponent on the damage characteristics, stress distribution and energy evolution were numerically and experimentally investigated. The results indicated that the smooth transition within through-the-thickness microstructures effectively avoided the occurrence of interlayer delamination or tearing. The compositional gradient exponent played an essential role in the impact response of the FGM targets. The FGM having a linear composition gradient outperformed other nonlinear types with respect to energy absorption and ballistic properties due to the reduced tensile wave strength and prolonged projectile-target interaction time. Furthermore, the structural optimization problem with the objective of maximizing ballistic efficiency was solved using the conjugate gradient method, and the optimal design of the FGM targets was achieved. The current research provides a promising design guideline for developing and optimizing new advanced lightweight composite armor.

Determination of the ballistic performance ramie-fiber-reinforced epoxy composite-sic ceramic in multilayered armor system

Multilayered Armor System (MAS) is being extensively studied around the world for its ability to retain ceramic fragmentation after a collision occurs. MAS consist of a ceramic layer placed at the front and supported by a composite layer of ramie-fiber-reinforced epoxy resin. Present study utilizes natural fibers of 50 % ramie fibers with epoxy resin as the matrix and Silicon Carbide (SiC) ceramic as the front panel. The ballistic testing in this study used 7.62×51 mm NATO Ball projectile with a firing distance of 15 m from the bullet panel. The velocity of projectile was detected using LIGHT SCREEN B471 type. The aim of the study is to conclude the optimal thickness of ramie fiber-epoxy and SiC ceramics MAS structure based on experiments which can withstand 7.62 NATO ball bullet penetration. To achieve this aim, the following objectives are accomplished: study the effect of SiC ceramic addition to ramie composite on BFS and study the effect of SiC ceramic addition to ramie composite on failure mode. Results show that the addition of the number of layers of SiC increases resistance of ballistic MAS marked by a decrease in the value of BFS clay. The 5SiC+10R is the optimal thickness in resisting the penetration of 7.62×51 mm bullets with 12 mm BFS clay. Failure phenomena found in this study were projectile fragments, matrix cracks, radial cracks, impact points, and ceramic fragments. Matrix crack formation appears on 5SiC+10R with mini deformation in rear side. Phenomenon of ceramic fragmentation in the shot causes the MAS structure to be damaged, so that the ramie fiber composite layer will face the bullet directly if it is subjected to a second shot. Ultra High Hardness Armor (UHHA) as first layer on the MAS structure is an attractive option for further research.

Ballistic design and testing of a composite armour reinforced by CNTs suitable for armoured vehicles

This paper is investigating the use of composite armour reinforced by nanomaterials, for the protection of light armoured (LAV) and medium armoured military vehicles (MAV), and the interaction between the composite materials and high-performance ballistic projectiles. Four armour materials, consisted of front hybrid fibre reinforced polymer cover layer, ceramic strike-face, fibre reinforced polymer intermediate layer and the metal matrix composite reinforced backplate, were manufactured and assembled by adhesive technology. The proposed laminated protection system is suitable for armoured ground vehicles; however, it could be used as armour on ground, air and naval platforms. The design of the protection system, including material selection and thickness, was elaborated depending on the performance requirements of Level 4 ＋ STANAG 4569 military standard (projectile 14.5 mm × 114 mm API B32) and especially on a design philosophy which is analysed with the specifications. The backplate of this new composite is a hybrid material of Metal Matrix Composite (MMC) reinforced with carbon nanotubes (CNTs), manufactured with the use of powder metallurgy technique. The composite backplate material was morphologically, mechanically and chemically analysed. Results show that all plates are presenting high mechanical properties and ballistic characteristics, compared to commonly used armour plates. Real military ballistic tests according to AEP - STANAG 4569 were carried out for the total composite armour systems. After the ballistic tests, AA2024-CNT3 showed the best protection results, compared with the other plates (AA2024-CNT1 and AA2024-CNT2), with the projectile being unable to fully penetrate the composite plate.

Effect of quilting pitch and sewing thread type on the fragment protective performance of para-aramid fabrics used in military body armour

Personal protective equipment (PPE) is crucial for military personnel who find themselves in hostile situations facing a prolific and focused enemy. PPE is designed to protect the wearer from injury and/or fatality, i.e. the use of PPE increases the likelihood of survivability. Military body armour, which protects the critical organs of the torso, contains multiple layers of para-aramid or ultra-high molecular weight polyethylene (UHMWPE) fabrics. These layers of fabric are often quilted for ease of handling during the construction of the armour and to prevent the slumping of the armour layers in the carrier and protect the wearer from fragmentation which is the major cause of injury in modern warfare. Minimal work has been published on the effect of quilting on the protection offered by military body armour. In this work, the effects of quilting pitch (none; bias direction −10, 20 and 30 mm pitch), sewing thread type (cotton, polyester-cotton, para-aramid, bonded nylon) and the number of layers (one, three) of a Twaron® fabric on the fragment protective performance was investigated with reference to military body armour systems. Evidence of a strain rate effect was noted. Use of 100% cotton or bonded nylon thread for quilting typically resulted in a higher energy dissipated (ED ) compared to not-quilted specimens. The greatest improvements were noted with bonded nylon quilted specimens. At slower velocities, this improvement was 94% for one-layer specimens and 32% for three-layer specimens. At faster velocities, this improvement was 41% for one-layer specimens and 32% for three-layer specimens.

Ballistic studies on synthetic fibre reinforced polymer composites and it’s applications –A brief review

Recent developments in the defense sector have led to the creation of a new high-performance composite synthetic fiber with excellent energy accumulation, endurance strength, and specific strength. However, selecting the appropriate synthetic fiber, processing technique, optimal plate thickness, and layer sequence when creating synthetic composite plates for defense purposes has proven challenging. There are still gaps in the selection of materials such as the matrix and fiber, processing techniques, weight fraction, and stacking sequence necessary for achieving optimal aerial density and better ballistic strength in armor systems. This review article aims to summarize the different materials based on synthetic fibers used for developing high-performance defense materials. Additionally, incorporating filler particles into synthetic fiber-reinforced composite materials has been explored as a means of improving ballistic strength. The article also examines the impact of stacking sequences on ballistic strength and various numerical methods for determining composite ballistic strength. Finally, the study concludes by discussing the changing trends in the ballistic performance of materials created with a single fiber or a combination of two or more fibers (hybrid).

Energy Absorption and Ballistic Performance of Epoxy Composite Reinforced with Arapaima Scales.

Arapaima scales possess a hierarchical structure capable of absorbing a considerable amount of energy before fracture. These natural dermal armors present significant potential in the sustainable development of cost-effective composites. This work aimed, for the first time, to analyze the impact resistance and ballistic performance of arapaima scale-reinforced epoxy composites and their potential application in multilayered armor systems (MAS). Composite plates were prepared with 20%, 30%, and 40 vol% of arapaima scales. Composite specimens were subjected to notched Izod impact and residual velocity stand-alone tests and their MAS through backface signature (BFS) tests, with their fracture surfaces studied using SEM. The Izod tests confirmed the effect of scales' volume fraction on the energy absorbed by the composites, showing an increase with volume fraction. Residual velocity tests showed that composites with 30 vol% of scales resulted in the most significant improvement in absorbed energy. All MAS formulations presented BFS depths lower than the trauma limit specified by the NIJ standard. Fractographic analysis showed that the scales' toughening mechanisms improved the composites' energy absorption capacity. The experimental results substantiate the potential use of arapaima scales as a reinforcement agent in polymeric composites, with 30 vol% being the optimal volume fraction for energy-absorbing applications.

Ballistic performance of integral body armor with closed-cell aluminum foam: A numerical study

This numerical study is dedicated to investigating the ballistic performance of three-component integral body armor comprising ceramic façade, layers of ultra-high molecular weight polyethylene fiber-based composite (Dyneema) and closed-cell aluminum foam against NIJ-Type IV armor-piercing bullets. A numerical model of integral armor with a ceramic façade and a fiber-reinforced composite backing plate was developed in IMPETUS Afea Solver and verified against experimental data. The verified model was used to design a "baseline configuration" of two-component integral armor that can stop the NIJ-Type IV projectiles. Three-component armor configurations were obtained by introducing layer(s) of closed-cell aluminum foam into the laminate. Laminates with different stacking sequences of composite and porous layers and different foam relative densities were studied and compared with the baseline two-component configuration. The study presents new insights into the mechanics of perforation of integral armor with closed-cell foam and provides design recommendations for such armor systems.

Effect of Aging on Unidirectional Composite Laminate Polyethylene for Body Armor.

The construction of ballistic-resistant body armor is experiencing an increasing use of flexible unidirectional (UD) composite laminates that comprise multiple layers. Each UD layer contains hexagonally packed high-performance fibers with a very low modulus matrix (sometimes referred to as binder resins). Laminates are then made from orthogonal stacks of these layers, and these laminate-based armor packages offer significant performance advantages over standard woven materials. When designing any armor system, the long-term reliability of the armor materials is critical, particularly with regard to stability with exposure to temperature and humidity, as these are known causes of degradation in commonly used body armor materials. To better inform future armor designers, this work investigates the tensile behavior of an ultra-high molar mass polyethylene (UHMMPE) flexible UD laminate that was aged for at least 350 d at two accelerated conditions: 70 °C at 76% relative humidity (RH) and 70 °C in a desiccator. Tensile tests were performed at two different loading rates. The mechanical properties of the material after ageing demonstrated less than 10% degradation in tensile strength, indicating high reliability for armor made from this material.

Damage formations of ramie fiber composites multilayer armour system under high-velocity impacts

Multilayer armour system (MAS) becomes the best choice in reinforcing protection for military officers against projectile attack which has a high velocity of up to 7.62×51 mm NATO ball lead core (projectile level III NIJ standard) or AP 7.62×51 mm hard steel core (projectile level IV NIJ standard). This study aimed to analyze the damage formation of wolfram carbide (WC) ceramic and ramie fiber composites. The frontmost MAS uses WC ceramic and is enveloped by a back layer of ramie fiber composites with epoxy resin reinforcing material as the matrix. Ballistic testing was carried out in this study using a long-barreled rifle to determine the resistance of the MAS from projectile impact. The speed meter in ballistic testing uses a velocity sensor type light screen B 471 and clay witness is used to measure back face signature (BFS). The results show that 7.62 lead core and hard steel core projectiles were unable to penetrate the 3-layer ceramic MAS in the front. The results are marked by a relatively low BFS value of 1.45 and 1.17 mm, so that the energy in the MAS with 3 ceramic layer is absorbed efficiently but with the phenomenon of rupture ceramic failure. Ceramic rupture failure needs to be overcome by bonding several layers of ramie so that MAS can be used in the next stage. MAS with 1 and 2 ceramic layers are unable to withstand projectile level III and level IV NIJ standard. From these results it is known that the MAS limit can withstand the projectile level III and IV NIJ standard, namely MAS with 3 ceramic layers. The damage formation of ceramic was rupturing ceramic failure. Therefore, it is necessary to design a ceramic binder by placing some ramie fibers in front of the ceramic

Concept of the defense material system for the security of Indonesian national armed personnel against threats

It is essential to have materials that can support armor systems for the application of body armor composed of anti-ballistic material from coated fibers in trials in order to defend military personnel with better ballistic performance who are lighter against growing threats and conflicts. to support defense-related ballistics. New materials used in personnel protection systems are the subject of this discussion. As ballistic shields, fiber composite materials are currently used due to their light weight and high flexibility. This essay also discusses a thorough analysis of mechanism performance and failure. This study's goal is to advance knowledge about composite material body armor that is covered with a soft spall liner material, which can be used as a model for lightweight, affordable, and safe designs for military troops in times of conflict.

Optimisation strategies for multi-layered armour plates

ABSTRACT A set of non-linear optimisation algorithms are combined with a finite element simulation code to analyse the energy absorption and elastic stress wave propagation problem in multilayer/multimaterial armour systems under ballistic impacts. An Abaqus Python script is used to simulate the ballistic event and to generate the variables and post-processing outputs necessary for the integration with the optimisation algorithms. A number of modelling strategies are considered and three optimisation algorithms are used: Particle Swarm Optimisation (PSO), Genetic Algorithm (GA) and Simulated Annealing (SA). The performance and efficiency of each algorithm are assessed through four benchmark tests with different levels of complexity. A multi-objective optimisation procedure is proposed that uses the most efficient algorithm based on every single-objective formulation, variables and constraints from the benchmark tests, resulting in a highly non-linear problem. The proposed optimisation methods successfully achieve the study purposes both in the simulation of generic ballistic impacts and in the quality of the optimised solutions, demonstrating the potential for this type of optimisation method on terminal ballistic applications, serving as a standpoint for further studies into higher energy impacts and material non-linearities.

Using CT scans to determine the optimal sizes of hard armour plates to protect the torso for UK female Armed Forces personnel

IntroductionHard armour plates provide coverage to essential anatomical structures in the torso that, if injured, would likely be responsible for death before damage control surgery can be undertaken. Existing front...

Design and Ballistic Performance of Hybrid Plates Manufactured from Aramid Composites for Developing Multilayered Armor Systems.

In this study, the impact resistance of aramid fabric reinforced with shear thickening fluids (STFs), epoxy or polyurea elastomers is examined through ballistic tests. According to the ballistic test results, the aramid composite structure treated with polyurea elastomers absorbs the most impact energy per unit area density and has the best impact resistance. However, the occurrence of stress concentration during ballistic impact reduces the impact resistance of the aramid composite structure treated with epoxy. On the other hand, aramid fabric impregnated with STF improves structural protection, but it also increases the weight of the composite structure and reduces the specific energy absorption (SEA). The results of this study analyze the energy absorption properties, deformation characteristics, and damage modes of different aramid composites, which will be of interest to future researchers developing next-generation protective equipment.

An Optimization Study on Material Selection for FRPCs in Multi Layered Armour System Through Hybrid MCDM Approach and Numerical Simulation

Fiber reinforced polymer composites (FRPCs) are considered as core structure in Multi layered armour systems (MAS) to take advantage of maximum energy absorption, mobility and cost criteria design. In this article, based on the problem defining attribute�s optimal material selection in FRPCs determined by Multiple criteria decisions making (MCDM) approach for considered alternative materials from polymer resin, synthetic and natural fiber. Attribute�s weightage and alternatives priority rank were determined through Fussy-Analytical hierarchy process (F-AHP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method. Obtained rank was compared with Preference selection index (PSI) an another MCDM method, for better computational conformity. Selected materials from MCDM approach, simulated for energy absorption ability and damage after impact were studied by considering Cowper-Symonds constitutive materials model using 3D macro shell analysis. Various impact velocities were considered from 3 to 50 m/s for rigid steel impactor directed towards the deformable plate. Parameter like Residual kinetic energy, Residual velocity, Energy absorption ratio after impact were studied numerically. Simulation results in terms of specific energy absorption were compared with the rank obtained in MCDM approach. Among the polymers considered epoxy, polyurethane and polyester found better choice. In fibers hemp and basalt found better materials choice for heterogenous FRPCs design in ballistic armour.