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Ballistic missile-resistant impact panels have seen fair advancement over the years, especially in military applications. However, high cost, as well as a changing materials landscape, has impressed the need for a deeper understanding of impact mechanism as well as of new permutations in design strategy development. Parameters such as projectile impact angle, panel impact location as well as application of multilayer sandwich panels are not fully explored and characterised. In this work, finite element method simulation methodology is used on a 25 mm by 25 mm plate of 3.5 mm thickness to investigate the above-mentioned parameters and conditions. Solid elements using Johnson–Cook damage material models are developed. Two common impact angles of 90 and 45° at centre and plate-edge locations are investigated for single-layer titanium alloy and carbon steel panels. Subsequently, a bilayer panel comprising of titanium alloy at the impact layer with the same overall plate thickness is investigated for impact at five different impact speed (ranging from 100 ms^-1 to 500 ms^-1). The displacements and von Mises stresses are documented for all cases, and it is shown that angular impact angles bring about greater plastic deformations as well as higher fracture likelihood compared to normal angle impact. Findings also indicate that with an addition of 1 mm thick Ti-6Al-4V front bilayer, the impact resistance of the high carbon steel is significantly improved (up to twice the impact load), especially at higher impact velocities. The study documents the properties of titanium alloy–carbon steel bilayer armoured panel, which shows good promise for its implementation due to its superior performance and its cost-savings potential.

In this work, finite element method simulation methodology is used to investigate the above-mentioned parameters and conditions. Solid elements using Johnson–Cook damage material models are developed. Two common impact angles 90 and 45° at centre and plate-edge locations are investigated for single-layer titanium alloy and carbon steel panels, and, subsequently, a bilayer panel comprising of titanium alloy for the outer layer is investigated for the combination of the same aforementioned materials. Five different impact speed effects are studied.

The effects and trends of displacements and stresses are documented for all cases and shown to indicate angular impact angles bringing about greater plastic deformations as well as higher fracture likelihood compared to normal angle impact. Findings also show that with an addition of 1 mm thick Ti-6Al-4V front bilayer, the impact resistance of the high carbon steel is significantly improved, especially at higher impact velocities.

The study documents the properties of titanium alloy–carbon steel bilayer armoured panel, which shows good promise for its implementation due to its superior performance and its cost-savings potential.

This paper aims to estimate the performance of protective clothing used to resist puncture (anti-stab property).

Seven single-layer (one layer) samples were investigated in this research. The first three samples were already used for the purpose of (anti-stab property), manufactured from Du-Pont product (commercial samples). The rest of the samples were locally designed and manufactured for the same purpose. These seven samples have then been examined after been added in conjunction with WL Kevlar XP (S 104) witness multilayers (eight layers) panel to create which are called multilayer samples.

The results of the statistical analysis for one-way ANOVA illustrated significant effect for single layer samples for all properties. While for multi-layer samples, the results showed a significant difference for all variables except displacement. The Tukey post hoc test observed a significant effect for some samples; also, other samples show a non-significant effect between samples.

It was observed that the locally manufactured samples serve the purpose as (anti-stab samples) compared with the commercial samples. The radar chart shows that for single-layer sample, the fifth sample fulfill the highest radar chart area, whereas for multi-layer samples, the sixth sample achieved the highest radar chart area.

A parallel finite‐element/multi‐body‐dynamics investigation is carried out of the effect of up‐armoring on the off‐road performance of a prototypical high‐mobility multipurpose‐wheeled vehicle (HMMWV). The paper seeks to investigate the up‐armoring effect on the vehicle performance under the following off‐road maneuvers: straight‐line flatland braking; straight‐line off‐angle downhill braking; and sharp left turn.

For each of the above‐mentioned maneuvers, the appropriate vehicle‐performance criteria are identified and the parameters used to quantify these criteria are defined and assessed. The ability of a computationally efficient multi‐body dynamics approach when combined with a detailed model for tire/soil interactions to yield results qualitatively and quantitatively consistent with their computational counterparts obtained using computationally quite costly finite element analyses is assessed.

The computational results obtained clearly reveal the compromises in vehicle off‐road performance caused by the up‐armoring employ to improve vehicle blast and ballistic protection performance/survivability. The results obtained are also analyzed and explained in terms of general field‐test observations in order to judge physical soundness and fidelity of the present computational approaches.

The paper offers insights into the effects of up‐armoring of the HMMWV on off‐road vehicle performance.

The ability of light‐weight all fiber‐reinforced polymer‐matrix composite armor and hybrid composite‐based armor hard‐faced with ceramic tiles to withstand the impact of a non‐Armor‐ Piercing (non‐AP) and AP projectiles is investigated using a transient non‐linear dynamics computational analysis. The results obtained confirm experimental findings that the all‐composite armor, while being able to successfully defeat non‐AP threats, provides very little protection against AP projectiles. In the case of the hybrid armor, it is found that, at a fixed overall areal density of the armor, there is an optimal ratio of the ceramic‐to‐composite areal densities which is associated with a maximum ballistic armor performance against AP threats. The results obtained are rationalized using an analysis based on the shock/blast wave reflection and transmission behavior at the hard‐face/air, hard‐face/backing and backing/air interfaces, projectiles’ wear and erosion and the intrinsic properties of the constituent materials of the armor and the projectiles.

Traditionally, an armor-grade composite is based on a two-dimensional (2D) architecture of its fiber reinforcements. However, various experimental investigations have shown that armor-grade composites based on 2D-reinforcement architectures tend to display inferior through-the-thickness mechanical properties, compromising their ballistic performance. To overcome this problem, armor-grade composites based on three-dimensional (3D) fiber-reinforcement architectures have recently been investigated experimentally. The paper aims to discuss these issues.

In the present work, continuum-level material models are derived, parameterized and validated for armor-grade composite materials, having four (two 2D and two 3D) prototypical reinforcement architectures based on oriented ultra-high molecular-weight polyethylene fibers. To properly and accurately account for the effect of the reinforcement architecture, the appropriate unit cells (within which the constituent materials and their morphologies are represented explicitly) are constructed and subjected to a series of virtual mechanical tests (VMTs). The results obtained are used within a post-processing analysis to derive and parameterize the corresponding homogenized-material models. One of these models (specifically, the one for 0°/90° cross-collimated fiber architecture) was directly validated by comparing its predictions with the experimental counterparts. The other models are validated by examining their physical soundness and details of their predictions. Lastly, the models are integrated as user-material subroutines, and linked with a commercial finite-element package, in order to carry out a transient non-linear dynamics analysis of ballistic transverse impact of armor-grade composite-material panels with different reinforcement architectures.

The results obtained clearly revealed the role the reinforcement architecture plays in the overall ballistic limit of the armor panel, as well as in its structural and damage/failure response.

To the authors’ knowledge, the present work is the first reported attempt to assess, computationally, the utility and effectiveness of 3D fiber-reinforcement architectures for ballistic-impact applications.

Nacre is a biological material constituting the innermost layer of the shells of gastropods and bivalves. It consists of polygonal tablets of aragonite, tessellated to form individual layers and having the adjacent layers as well as the tablets within a layer bonded by a biopolymer. Due to its highly complex hierarchical microstructure, nacre possesses an outstanding combination of mechanical properties, the properties which are far superior to the ones that are predicted using techniques such as the rule of mixtures. Given these properties, a composite armor the structure of which mimics that of nacre may have improved performance over a monolithic armor having a similar composition and an identical areal density. The paper aims to discuss these issues.

In the present work, an attempt is made to model a nacre-like composite armor consisting of B₄C tablets and polyurea tablet/tablet interfaces. The armor is next tested with respect to impact by a solid right circular cylindrical (SRCC) rigid projectile, using a transient non-linear dynamics finite-element analysis. The ballistic-impact response and the penetration resistance of the armor are then compared with that of the B₄C monolithic armor having an identical areal density. Furthermore, the effect of various nacre microstructural features (e.g. surface profiling, micron-scale asperities, mineral bridges between the overlapping tablets lying in adjacent layers, and B₄C nano-crystallinity) on the ballistic-penetration resistance of the composite armor is investigated in order to identify an optimal nacre-like composite armor architecture having the largest penetration resistance.

The results obtained clearly show that a nacre-like armor possesses a superior penetration resistance relative to its monolithic counterpart, and that the nacre microstructural features considered play a critical role in the armor-penetration resistance.

The present work indicates that for a given choice of armor material, penetration resistance may be improved by choosing a structure resembling that of nacre.

IT is unfortunate that the date of the 17th Salon de l'Aeronautique made it impossible to include a review of it in the December issue of AIRCRAFT ENGINEERING, although perhaps its consideration in retrospect may be of rather greater value.

To overcome the problem of inferior through-the-thickness mechanical properties displayed by armor-grade composites based on 2-D reinforcement architectures, armor-grade composites based on 3D fiber-reinforcement architectures have recently been investigated experimentally.

The subject of the present work is armor-grade composite materials reinforced using ultra-high-molecular-weight polyethylene fibers and having four (two 2D and two 3D) prototypical architectures, as well as the derivation of the corresponding material models. The effect of the reinforcement architecture is accounted for by constructing the appropriate unit cells (within which the constituent materials and their morphologies are represented explicitly) and subjecting them to a series of virtual mechanical tests. The results obtained are used within a post-processing analysis to derive and parameterize the corresponding homogenized-material models. One of these models (specifically, the one for 0°/90° cross-collimated fiber architecture) was directly validated by comparing its predictions with the experimental counterparts. The other models are validated by examining their physical soundness and details of their predictions. Lastly, the models are integrated as user-material subroutines, and linked with a commercial finite-element package, in order to carry out a transient non-linear dynamics analysis of ballistic transverse impact of armor-grade composite-material panels with different reinforcement architectures.

It is found that the reinforcement architecture plays a critical role in the overall ballistic limit of the armor panel, as well as in its structural and damage/failure response.

To the authors’ knowledge, the present work is the first reported attempt to assess, computationally, the utility and effectiveness of 3D fiber-reinforcement architectures for ballistic impact applications.

Bristol Composite Materials Engineering Ltd (BCME) is a wholly owned subsidiary of The British Petroleum Company plc (BP), operating as part of the BP Advanced Materials group of companies, and is involved in the design, development and manufacture of advanced composite components and structures. BCME has the experience and capability to manufacture a wide range of products for aerospace, defence and general industrial applications including aircraft interior structures, using advanced composite materials, offering significant weight saving, extended fatigue life and corrosion resistance when compared with metal equivalents.

The first part of this article appeared in our August issue and dealt with Lubrication Organisation, storing and handling at The Steel Company of Wales. Since writing this the author informs us that a Supervisor has now been appointed at the Margam plant and he will build up a similar organisation to that now operating at the Abbey Works.