This is a very timely review of body armour materials and systems since new test standards are currently being written, or reviewed, and new, innovative products released. Of greatest importance, ...however, is the recent evolution, and maturity, of the Ultra High Molecular Weight Polyethylene fibres enabling a completely new style of system to evolve – a stackable system of Hard Armour Plates. The science of body armour materials is quickly reviewed with emphasis upon current understanding of relevant energy-absorbing mechanisms in fibres, fabrics, polymeric laminates and ceramics. The trend in on-going developments in ballistic fibres is then reviewed, analysed and future projections offered. Weaknesses in some of the ceramic grades are highlighted as is the value of using cladding materials to improve the robustness, and multi-strike performance, of Hard Armour Plates. Finally, with the drive for lighter, and therefore smaller, soft armour systems for military personnel the challenges for armour designers are reported, and the importance of the relative size of the Hard Armour Plate to the Soft Armour Insert is strongly emphasised.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The behaviour of typical armour steel material under large strains, high strain rates and elevated temperatures needs to be investigated to analyse and reliably predict its response to various types ...of dynamic loading like impact. An empirical constitutive relation developed by Johnson and Cook (J–C) is widely used to capture strain rate sensitivity of the metals. A failure model proposed by Johnson and Cook is used to model the damage evolution and predict failure in many engineering materials. In this work, model constants of J–C constitutive relation and damage parameters of J–C failure model for a typical armour steel material have been determined experimentally from four types of uniaxial tensile test. Some modifications in the J–C damage model have been suggested and Finite Element simulation of three different tensile tests on armour steel specimens under dynamic strain rate (10−1s−1), high triaxiality and elevated temperature respectively has been done in ABAQUS platform using the modified J–C failure model as user material sub-routine. The simulation results are validated by the experimental data. Thereafter, a moderately high strain rate event viz. Charpy impact test on armour steel specimen has been simulated using J–C material and failure models with the same material parameters. Reasonable agreement between the simulation and experimental results has been achieved.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Ballistic performance of an Ultra High Hardness armour steel was evaluated.•Material.•Effect of plate hardness on performance against AP and fragment threats was studied.•Measured hardness vs. V50 ...performance was compared with common empirical models.
The ballistic performance of an ultra-high hardness armour steel (UHA) has been evaluated for a range of thicknesses and obliquities against armour piercing (AP) and fragment simulating projectiles (FSPs). Together with published literature, these results enable the effect of plate hardness on performance against both AP and FSP threats to be characterized over a range of plate hardnesses from ~ 300 to 600 HB. For AP projectiles, a complex relationship was observed that corresponded well with historical phenomenological curves describing the effect of varying projectile and armour failure mechanisms. In the ultra-high hardness regime (> 570 HB), against AP projectiles with core hardnesses of 610–745 HB (i.e. 7.62 mm APM2 and 12.7 mm APM2 projectiles), projectile shatter was demonstrated to be the controlling mechanism of armour performance. Against much softer FSPs (281 HB), where projectile shatter is not a relevant mechanism, the armour performance was found to initially decrease with increasing plate hardness up to ~ 450 HB due to increased susceptibility to adiabatic shear plugging. Above ~ 450 HB the performance was observed to plateau. The observed performance plateau appears to relate to a critical threshold for adiabatic shear failure beyond which further increases in plate hardness will not result in a decrease in performance. A number of common empirical and analytical models were applied to reproduce the experimentally-determined relationship between hardness and penetration resistance, none of which were able to qualitatively or quantitatively reproduce the observed relationships for either projectile class.
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Designing and manufacturing multi-functional, lightweight and high-performance body armour materials and assemblies have attracted intense attention recently due to fast-growing military ...applications. There is an urgent need to reduce the weight and increase the flexibility of body armours without compromising their ballistic protection capability. Natural/biological armour materials and assemblies offer remarkable properties that can inspire the design of lightweight, flexible and tough body armours. In this paper, a systematic review is conducted to identify the structural-mechanical characteristics of selected biological armour systems such as nacre from mollusc shells, conch shells and fish scaled skin. Other biological structures with the potential for ballistic protection have also been investigated, including crustacean exoskeletons and compact bone, which possess structures with important features and properties that may inspire the development of future soldier armours. The techniques and methodologies available for the analysis, fabrication and experimental investigations of bio-inspired armour composites and systems are also reviewed in detail. The investigations that have been found to be most relevant to the development of bio-inspired armour systems for dynamic impact resistance have also been discussed. This discussion can inspire the design of lighter and flexible bio-inspired armour systems that are more efficient in resisting ballistic attacks.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Cage armour systems have been in use since the 1960s and are still being used extensively on many armoured vehicles up to this day to offer protection against mainly a number of RPG-7 shaped charge ...warheads. Nevertheless, many misunderstandings still exist up to this day as well as regarding their working principle as regarding their actual efficiency. This article will start by exploring the origins of the current cage armour systems and by explaining the working principle behind them. This will be followed by the development of a methodology to calculate the efficiency of different types of cage armour systems (slat, bar, net and inertial distributed weight systems) as a function of impact conditions for a specific RPG-7 shaped charge warhead. The results of the developed methodology will be compared to experimental results for four different cage armour systems, in order to validate the followed approach. It will then be applied to different cage armour systems in order to calculate their overall ballistic and mass efficiency as a function of the impact angle. The analysis will finally be refined taking into account the likely impact conditions for an RPG-7 shaped charge warhead, based on a simple trajectory model.
The present study suggests a complete analytical model for armour perforation by ductile hole enlargement process. The new approximate model is applicable for entry, tunnelling and exit phases of a ...rigid nose-pointed projectile with an arbitrary nose-shape. The theory is based on dividing the target into infinitesimal thin layers, in which a cylindrical hole expansion is assumed. The elastoplastic work that is consumed by the target for infinitesimal projectile advancement is based on the specific cavitation energy and leads to reduction of the projectile kinetic energy. Several equivalent formulae for ballistic limit velocity, and a formula for the ballistic limit thickness are found to be independent of projectile nose-shape and nose length. The approximate model is compared with numerical simulations for AA6061-T651 targets that are impacted by two different ogive nose-shape projectiles at several striking velocities. A small nose-shape effect on the ballistic limit velocity is observed in the numerical simulations and is attributed mainly to the target axial effect and the bulge formation at the target rear surface, which are not considered in the approximate model.
•Analytical model for armour perforation by ductile hole enlargement is suggested.•The approximate model is applicable for entry, tunnelling and exit phases.•The model assumes rigid nose-pointed projectiles with arbitrary nose-shapes.•The model is compared with FE numerical simulations for AA6061-T651 targets.•The aluminium targets are impacted by two different ogive nose-shape projectiles.
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In the paper there are presented general parameters of shaped charge projectiles (SC) and explosively formed projectiles (EFP), designed for destroying of armed vehicles, and parameters of explosive ...reactive armours (ERA), which significantly increase capability of protection of rolled homogeneous armour (RHA) against piercing by these projectiles. There are shown examples of destruction of tanks not protected by the ERA. Their parameters are presented on the base of ERAWA-1 and ERAWA-2 Polish reactive cassettes for PT-91 Hard tank. There are described the following requirements: capability of protection of ERAWA-1 and ERAWA-2 cassettes as a result of reaction in the static test of shaped charge projectiles PG-7 and 125 mm BK-14M, effect in the dynamic test of 125 mm BM-15 projectile that pierces through due to its kinetic energy, and resistance to detonation of the cassettes fired by 12.7×107 mm AP B-32 projectiles. There are demonstrated results of the resistance to detonation of the neighboring ERAWA cassettes in case of detonation of the central cassette in the panel. There are presented results of test of resistance to detonation of the ERAWA cassettes while burning on them flammable material (gasoline, napalm), and resistance to detonation of the cassettes dropped from 3 m height onto a hard substrate of RHA. The safe distance for humans after detonation of the projectile and ERAWA-2 cassette was also tested.
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 User-friendly overview of all such interfaces and provide unique guidance as to their criticality and influence.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The use of advanced ceramics for armour systems allows the defeating of the projectile and ballistic impact energy dissipation providing adequate ballistic protection. The development of lightweight ...and inexpensive ceramics and armour designs is under ongoing attention by both ceramic armour manufacturers and armour users. This paper summarizes the results of extensive studies of ballistic performance of different armour ceramics, mostly obtained during development, as well as of the materials manufactured by other recognized armour ceramic suppliers, and the designed ceramic-based armour systems. The studied armour ceramics include homogeneous oxide and carbide ceramics and heterogeneous ceramic materials. Composition, structure and main properties of the considered ceramics, which affect ballistic performance, are examined and analyzed. Only a combination of all relevant physical properties and microstructure, including the ability to dissipate ballistic energy, as well as optimization of manufacturing processes, should be considered for proper selection and evaluation of ceramic armour. Ballistic performance of the studied ceramics as function of their structure and properties, armour system design and type of projectile has been discussed.
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