Ballistic Limit Velocity Research Articles

Approximate theory of armour perforation by ductile hole expansion

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.

Experimental and numerical investigations of damage and ballistic limit velocity of CFRP laminates subject to harpoon impact

The harpoon is a space debris capture mechanism with strong adaptability to targets. In this paper, experiments and finite element models are used to study the harpoon impact on carbon fiber laminate. Firstly, a harpoon penetration gas gun experiment was designed to obtain the damage and ballistic limit velocity of carbon fiber laminates. Then finite element modeling and numerical simulation of the impact on the laminate were carried out using the user–defined VUMAT subroutine in ABAQUS, focusing on the ballistic limit velocity change, damage evolution of the laminate and energy absorption of the laminate when the harpoon penetrates the laminate obliquely at a specific angle. The results showed that compared with vertical penetration, the ballistic limit velocity of harpoon increased by 3.2 %, 9.6 % and 24.3 % respectively under 15°, 30° and 45° oblique penetration conditions; and with the increase of harpoon impact angle, the damage of laminates gradually tended to occur on one side of the projection of harpoon on laminates; while in terms of energy absorption, the energy absorption of laminates for the same angle tended to a constant value as the launch velocity increased.

Experimental and numerical investigation on Multiwalled carbon nanotubes (MWCNTs) dispersed CFRP laminate subjected to spherical and conical impacts

ABSTRACT As lightweight and load-bearing efficiency needs have grown, conventional metal has steadily given way to carbon fibre-reinforced polymer (CFRP) laminates. Also, CFRP laminates are more prone to localised damage due to impact loads like tool drop, runway debris and hail stone. This paper, investigated the penetration and perforation behaviour of CFRP laminate reinforced with 0.2 and 0.5 wt% MWCNTs. The projectile impact experiment was conducted using spherical and conical projectiles and the impact resistance was evaluated. The results revealed that 0.5 wt% MWCNTs embedded in CFRP laminate provided better impact resistance to both projectiles. The ballistic limit velocity was enhanced by 14.2% and 17.9% for spherical and conical projectiles, respectively, in the case of 0.5 wt% MWCNTs. Furthermore, numerical simulations were performed using an orthotropic model with Chang-Chang composite failure criteria. The results from numerical findings were consistent. It was concluded that MWCNTs reinforcement improves the projectile impact resistance and energy absorption.

High-velocity impact performance of sandwich panels with additively manufactured hierarchical honeycomb cores: An experimental and numerical study

The honeycomb sandwich panel presents a highly promising solution for enhancing ballistic behavior owing to its excellent strength-to-weight ratio and impact resistance. This study focuses on investigating the shock mitigation properties of honeycomb sandwich panels through experimentation and numerical simulation of high-velocity impact tests. Single-scale and double-scale hierarchical honeycomb cores are manufactured using selective laser melting with AlSi10Mg powder, combined with a pair of stainless steel (SS 316) sheets. High-velocity impact experiments were conducted within a velocity ranging from 100 to 270 m/s to examine the effects of different cores and projectile nose shapes on the dynamic response of the panels. Numerical simulations using ABAQUS/Explicit software were performed and validated against the experimental results. The sandwich panel with a double-scale hierarchical honeycomb core exhibited 7.8% and 6.1% more energy absorption compared to the single-scale hierarchical honeycomb core against conical and hemispherical nose projectiles, respectively. Additionally, the ballistic limit for the hemispherical projectile was found to be 8.9% higher than the conical-nose projectile under the same impact velocity and panel thickness. Moreover, an increase in panel thickness from 12 mm to 25 mm prompted a significant improvement of approximately 39% in specific energy absorption and a 44% increase in ballistic limit velocity. These findings highlight the considerable potential of single-scale and double-scale hierarchical honeycomb sandwich panels for the development of threat-resistant structures in critical dynamic loading applications.

The penetration resistance behavior and corresponding size effects of ultra-high molecular weight polyethylene composite laminates

Focusing on the energy absorption characteristics of ultra-high molecular weight polyethylene (UHMWPE) fiber laminated panels, this study conducts ballistic tests and numerical simulations using 6 mm spherical projectiles to impact the UHMWPE laminated panels. The residual velocity characteristics, energy absorption patterns, and failure modes of the UHMWPE laminated panels under steel ball impacts were analyzed. The results show that the residual velocity of the steel ball increases with the increase of the incident velocity. In the velocity range near the ballistic limit velocity, the residual velocity of the steel ball increases sharply. When the incident velocity exceeds 340 m/s, the increase in residual velocity gradually slows down, tending towards a straight line. When the steel ball velocity is less than 330 m/s, the energy absorption of the UHMWPE laminated panels exhibits linear growth with increasing velocity, with a maximum energy absorption of 47.3 J. In the 327–340 m/s velocity range, the energy absorption of the laminated panels drops sharply from 47 J to around 30 J. In the 340 m/s–600 m/s velocity range, the decline in energy absorption gradually becomes more moderate, decreasing to around 20 J. Beyond 500 m/s, the energy absorbed by the UHMWPE laminated panels stabilizes with increasing velocity, and the fiber tensile failure is the main form of energy absorption of UHMWPE composite laminates under ballistic impact. The failure process of UHMWPE laminated panels presents a multi-stage failure mode, including fiber shear failure, tensile failure, and delamination. As the projectile’s incident velocity increases, the damage mechanism of the UHMWPE laminated panels transitions from tensile-dominated to shear plugging-dominated. Through similarity theory analysis, under certain conditions, the ballistic limit velocity and the dimensionless parameter of unit energy absorption for the UHMWPE laminated panels satisfy geometric similarity.

Comparative study of hardfacing applications on structural steel surfaces to improve ballistic properties

The aim of this study was to develop plates resistant to ballistic limits by welding on S355JR steel plate with Fe-Cr-C and austenitic electrodes. A total of four different weld coated materials were prepared for ballistic testing. For these four different coatings, E Z Fe 14 (Fe 14), E Fe 16 (Fe16) hardfacing electrodes and E 18 8 Mn R 3 2 (307) austenitic stainless steel electrode were selected, respectively. The coatings were made in the electric arc welding machine, with two different coatings on the surface for each material. These are Fe 14 – Fe 14, Fe 16 – Fe 16, 307-Fe 14 and 307-Fe 16, as the first layer and the second layer, respectively. In all coatings, the welding current was kept constant at 150 A and the welding voltage was kept constant at 27 V. The microstructure, hardness, and ballistic properties of the hardfacing surfaces were investigated using scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) to analyze the phases and components. The hardnesses of the hardfacing surfaces were determined by Vickers methods from the weld metal to the base metal. Ballistic tests were conducted according to NIJ Level III standards, firing 7.62 × 51 mm AP bullets from a distance of 10 m to calculate the effects of the bullets on the plates, the kinetic energy of the bullet, and the amount of energy absorbed by the plates. Welding for hard surface coating achieved with the combination of 307 - Fe 14 electrodes provides the highest ballistic limit velocity at 830 m/s, while the lowest limit is observed in the material welded with Fe16-Fe16 electrodes at 747 m/s. Fe-Cr-C electrodes were found to be effective as main or auxiliary components when designing armor plates. This study highlights the potential of hardfacing techniques to improve the ballistic properties of steel surfaces, with implications for the development of protective materials across various industries.

Dynamic behaviour of multi-layer composite against single and multiple projectile impact loading

In this work, a novel multi-layer composite structure has been proposed for its application in the design of protective shelters. The proposed work investigates the dynamic behaviour of a multi-layer composite under the action of single and multiple projectile impact loading. The target consists of soil, reinforced concrete, steel plate, high-density polyethylene and boulder-mixed cement mortar. It has been subjected to the projectile impact (single and multiple) of a 2.3 kg ogive-nose hard cylindrical projectile having a 50.80 mm diameter. The mechanical performance in terms of the velocity profile of the projectile, residual velocity, penetration depth, ballistic limit velocity, energy absorption and damage of the target has been quantified through a numerical framework. Further, equations have been formulated to determine the fracture material parameters associated with the Riedel–Hiermaier–Thoma (RHT) model to cater for varying strengths of concrete or similar materials. The proposed composite target has demonstrated enhanced penetration resistance and lesser damage compared to its reinforced concrete monolayer counterpart. The interaction between shock waves and the target’s material characteristics lead to projectile ricocheting in multiple projectile impacts. Further, an analytical model has been developed to predict the forces transmitted to the lowest layer, which are essential for design purposes. The model has been proposed from the fundamentals using the concepts of impedance. The result derived from the theoretical formulation is in good agreement with the numerical results. Finally, the damage has been quantified to assess the extent of structural deterioration in multi-layer targets, emphasizing the relationship between energy absorption ratio and damage.

Synthesis and modification of poly (p‐phenylene terephthalamide) for production of light‐weight hybrid composite armors reinforced with polymer composite nanofiber mats

AbstractPoly (p‐phenylene terephthalamide) (PPTA) polymer was synthesized and then modified to eliminate the processing difficulties arising from its insolubility in organic solvents. The chemical structures of the synthesized PPTA and N‐butyl PPTA (BPPTA) were confirmed by elemental analysis, x‐ray diffraction, Fourier transform infrared (FTIR), and 13C‐NMR spectroscopy studies. As a result of modification, an aramid derivative that is soluble in some common solvents was obtained and added into polyacrylonitrile (PAN) matrix in solution. PAN/BPPTA composite nanofiber mats (CNMs) were fabricated by electrospinning. Mechanical tests showed that tensile strength increased by 119% with 3% BPPTA content. The fabricated CNMs were combined with aramid fabrics to produce laminated hybrid armors and ballistic tests were performed following the NATO Stanag 2920 standard. This is the first report about the integration of CNMs into multilayer armor configurations and resulted in improved ballistic limit velocity (V50) with a relatively very small weight gain and emergence of new energy absorption mechanisms.Highlights Alkylation of the para‐aramid yielded an organo‐soluble aramid derivative. Tensile strength of PAN nanofiber mat increased by 119% with 3% N‐butyl PPTA. Integration of the CNMs resulted in new ballistic impact absorption mechanisms. CNMs contribute to V50 with a very low mass gain due to their high surface area/mass.

A data-driven approach for predicting the ballistic resistance of elastoplastic materials

Data-driven methods and machine learning methods provide efficient and accurate approaches for solving impact problems. In this paper, a data-driven approach is proposed for numerical simulations of ballistic impact behavior for elastoplastic materials. An enhanced rate-dependent scheme is employed for improving the predictability of the data-driven constitutive model. A new method that introduces a stress triaxiality indicator to three separate constitutive models is proposed to consider the discrepancy between the mechanical responses of materials under tension, compression, and shear. Additionally, a modified Bai-Wierzbicki fracture criterion considering the strain rate effect and the stress-state effect is used to evaluate the fracture behavior of the materials during impact simulations. Subsequently, a compatible numerical implementation algorithm that considers loading, unloading, and reverse loading is established to enable the application of the data-driven approach in finite element simulations. Numerical validation of the proposed data-driven approach is conducted through several simple loading examples, such as cyclic loading, torsional loading, and tension–torsion combined loading. The data-driven approach is then employed to simulate the ballistic impact behavior of Ti-6Al-4V targets of different thicknesses that are struck by blunt projectiles. Impact properties—including the relationship between residual velocity and impact velocity, ballistic limit velocities, and fracture paths—are comprehensively studied. The results demonstrate the reasonable predictability and accuracy of the data-driven approach when applied to ballistic impact simulations.

Ballistic response of additively manufactured AA6061/AA7075 multistack plate for armor-piercing projectile

The current ballistics research study focuses heavily on substituting heavy metals with lightweight materials to make mobility more accessible and effective for all armor applications. To do so, the researchers found that aluminum alloys are the better alternative to substitute steel armor due to their high strength-to-weight ratio. Therefore, this research conducted ballistic studies on aluminum alloys using the Finite Element Analysis (FEM) methodologies and associated mathematical analysis. This Research primarily focuses on the damage factor, ballistic limit, and residual velocity of the bullet following penetration of target plates. In this investigation, the Johnson-Cook fracture and Recht-Ipson models were implemented on materials AA6061-T6 and AA7075-T6. The main objective of these models is to establish the damage factor and verify whether it is less than unity; if the factor is less than unity, it is eligible to study the residual velocity of the bullet after penetration into the target armor plate. The target plate was impacted with a 7.62 mm armor-piercing projectile with an impact velocity of 500 m/s. Monolithic plates of 18 mm thickness were evaluated initially. After that, the multilayered stack of each 3 mm thick plate was analyzed, and studied the effectiveness of using a multilayered stack armor plate.

Energy dissipation mechanism and ballistic characteristic optimization in foam sandwich panels against spherical projectile impact

This study systematically examines the energy dissipation mechanisms and ballistic characteristics of foam sandwich panels (FSP) under high-velocity impact using the explicit non-linear finite element method. Based on the geometric topology of the FSP system, three FSP configurations with the same areal density are derived, namely multi-layer, gradient core and asymmetric face sheet, and three key structural parameters are identified: core thickness (tc), face sheet thickness (tf) and overlap face/core number (no). The ballistic performance of the FSP system is comprehensively evaluated in terms of the ballistic limit velocity (BLV), deformation modes, energy dissipation mechanism, and specific penetration energy (SPE). The results show that the FSP system exhibits a significant configuration dependence, whose ballistic performance ranking is: asymmetric face sheet > gradient core > multi-layer. The mass distribution of the top and bottom face sheets plays a critical role in the ballistic resistance of the FSP system. Both BLV and SPE increase with tf, while the raising tc or no leads to an increase in BLV but a decrease in SPE. Further, a face-core synchronous enhancement mechanism is discovered by the energy dissipation analysis, based on which the ballistic optimization procedure is also conducted and a design chart is established. This study shed light on the anti-penetration mechanism of the FSP system and might provide a theoretical basis for its engineering application.

Ballistic performance of double-layered plates Q235 and 45 steel subjected to impact by projectiles of middle strength

The ballistic resistance behavior of double-layer steel plates incorporated with different materials is experimentally and numerically investigated by using blunt- and ogive-nosed projectiles of middle strength. These materials are Q235 steel (low strength and high ductility) and 45 steel (high strength and low ductility). Experimental results showed that the ballistic resistance is better for the double-layer plates with the front layer of low ductility and high strength and the back layer of high ductility and low strength material than that of the opposite layer order impacted by ogive-nosed projectiles, but the situation is opposite for blunt-nosed projectiles. The ballistic limit of H + A (753.85 m/s) is increased by 29.5% when compared to that of A + H (582.19 m/s) for ogive-nosed projectiles of 45 steel. In the case of blunt projectiles, a 2.8% decrease in the ballistic limit of middle-strength projectile. Ogive-nosed projectiles are more sensitive than blunt-nosed projectiles when it comes to the effect of the layer order of the double-layer plates. Moreover, the ballistic limit velocities of blunt-nosed projectiles are obviously bigger than that of ogive-nosed projectiles for the double-layer plates of the front layer of low strength, while the situation is opposite for the double-layer plates of the front layer of high strength. Furthermore, the projectiles lose some mass and length after impact. The deformation of projectiles is also concerning the nose shape and velocity of projectiles, as well as the layer order of the double-layer plates. Finally, numerical simulation results are obtained and compared using the ABAQUS subroutine VUMAT-modified Johnson-Cook material model. And these results fairly agree with the experiment.

Enhancing the ballistic resistance of steel/aluminum bilayer armor plates through explosive welding

This work presents a comprehensive analysis of the ballistic response of Q235 steel/6061-T6 aluminum bilayer plates fabricated via explosive welding, with a special focus placed on elucidating the mechanisms of ballistic resistance enhancement due to the bonded interface. For comparison purposes, unbonded Q235 steel/6061-T6 aluminum bilayer plates (e.g. being stacked together or spaced with an air gap) were also investigated. Ballistic tests were carried out to compare the residual velocities and failure behaviours of the welded and unwelded bilayer plates. Computational models were built in LS/DYNA and validated with the experiment. Experimental results showed that the ballistic limit velocity of the explosively-welded plate is 13.4% and 9.4% higher than those of the in-contact plate and air-gapped plate. Simulation results suggested that the enhanced ballistic resistance was attributed to its welded interface. On the one hand, the welded interface allowed effective stress attenuation within the steel layer leading to a greater damage tolerance and more energy dissipation during the prolonged response time. On the other hand, when deforming together with the steel layer, the welded interface enforced a uniform indentation on the central region of the aluminum substrate leading to greater energy absorption due to compression and thinning of the material.

A comparative study on dynamic deformation and ballistic impact response of Ti–4Al–2.5V–1.5Fe–0.25O and Ti–6Al–4V alloys

Titanium alloys are most suitable for lightweight armour applications due to their superior strength to weight ratio, and α+β Ti alloy Ti–6Al–4V is widely used in armour applications. One of the critical factors limiting the widespread use of Ti alloys in armour application is their high cost. Recently, Allegheny Technologies Incorporated introduced ATI-425® Ti alloy with the chemical composition of Ti–4Al-2.5V-1.5Fe-0.25O as a low-cost alternative to Ti–6Al–4V. Though ATI-425 Ti alloy is primarily intended for armour applications, only limited ballistic results are available in the open literature. In the present work, we compare the quasi-static, dynamic deformation, ballistic impact response and post-deformation microstructure of a low-cost α+β Ti alloy ATI-425 with that of Ti–6Al–4V alloy. Analysis of the results showed that both alloys showed similar yield strength values during quasi-static tension and compression tests, while ATI-425 Ti alloy showed higher tensile ductility, Charpy-V notch impact energy and dynamic flow stress than Ti-6Al-4V. The ATI-425 Ti alloy also exhibited slightly better ballistic performance measured in terms of V50 ballistic limit velocity. Detailed microstructural analysis on quasi-static and dynamic compression-tested samples showed mainly {101–2} tensile twins, whereas {101–2} and {112–1} tensile twins are observed in ballistic-tested samples of both the alloys. Activation of deformation twinning in ATI-425 Ti alloy with higher oxygen is attributed to lower Al content which enhances the twinning activity. Adiabatic shear band (ASB)-induced plugging mechanism is ascertained as the perforation mode in both alloys during the ballistic impact. Analysis of propensity to ASB formation indicated that Ti-6Al-4V has a slightly better resistance to ASB formation than ATI-425 Ti alloy. The improved ballistic performance of ATI-425 Ti alloy in comparison to Ti-6Al-4V is attributed to the higher dynamic flow stress, Charpy-V notch impact energy absorption, and moderate resistance to adiabatic shear band formation.

ZK61m magnesium alloy plate thickness effect on the impact characteristics of blunt projectiles experimental and numerical simulation studies

To study the impact resistance of ZK61m magnesium alloy plate, firstly, impact experiments were conducted on magnesium alloy plates of different thicknesses using a one-stage gas gun system to obtain the ballistic limit velocity (BLV) and failure mode of the target plate. In addition, the velocity of the punch plug was analyzed by the squeeze chisel block velocity model. Finally, the corresponding numerical simulations were carried out using the Lode parameter-independent MJC fracture criterion and the Lode parameter-dependent MMC fracture criterion, and the influence mechanism of the Lode parameter on the numerical simulation results was analyzed. The results show that under the impact of the blunt projectile, different thicknesses of target plates mainly occur shear plug failure, the BLV first tends to flatten and then increases sharply with the increase of its thickness. Besides, in the same velocity interval, the plugging velocity decreases with the increase of the target plate thickness; the Lode parameter has an obvious influence on the simulation results, which the MMC fracture criterion is more consistent with the experimental results. However, with the increase of the target plate thickness, both MMC and MJC fracture criteria show the phenomenon of overestimation of the material ductility.

Finite element analysis of the ballistic performance of monolithic and double-layered plates subjected to deformable projectiles

Impact problems have always been a field of interest for researchers because of their wide application in industries, especially in producing protective structures in defence. In the present study, finite element analysis is used to analyze the ballistic performance of monolithic and double-layered plates against cylindrical projectile with different nose shapes, viz. trapezoidal and flat-nosed, using a dynamic temperature displacement explicit analysis in the commercial finite element software ABAQUS. Further, the study compares the ballistic resistance (BR) of plates with different thicknesses (6, 10, and 12 mm) against the same configuration of projectiles. The Johnson–Cook (JC) constitutive strength and damage model characterizes the target and projectile material behavior. Mie–Grüneisen equation of state describes the material behavior of projectile and target under high pressure. The impact response of the target is compared in terms of plate deformation, ballistic limit velocity, and failure pattern of targets during impact. The monolithic plate has 2.42% higher impact resistance than the double-layered plate for the trapezoidal-nosed projectile, while for a flat-nosed projectile, double-layered plates have 9.42% higher BR than the monolithic plates. Moreover, the BR of plates (6, 10, and 12 mm) for flat-nosed projectiles is found to be 7.94, 5.56, and 4.59% higher than trapezoidal-nosed projectiles.

Improved Ballistic Impact Resistance of Nanofibrillar Cellulose Films with Discontinuous Fibrous Bouligand Architecture.

Natural protective materials offer unparalleled solutions for impact-resistant material designs that are simultaneously lightweight, strong, and tough. Particularly, the Bouligand structure found in the dactyl club of mantis shrimp and the staggered structure in nacre achieve excellent mechanical strength, toughness, and impact resistance. Previous studies have shown that hybrid designs by combining different bioinspired microstructures can lead to enhanced mechanical strength and energy dissipation. Nevertheless, it remains unknown whether combining Bouligand and staggered structures in nanofibrillar cellulose (NFC) films, forming a discontinuous fibrous Bouligand (DFB) architecture, can achieve enhanced impact resistance against projectile penetration. Additionally, the failure mechanisms under such dynamic loading conditions have been minimally understood. In our study, we systematically investigate the dynamic failure mechanisms and quantify the impact resistance of NFC thin films with DFB architecture by leveraging previously developed coarse-grained models and ballistic impact molecular dynamics simulations. We find that when nanofibrils achieve a critical length and form DFB architecture, the impact resistance of NFC films outperforms the counterpart films with continuous fibrils by comparing their specific ballistic limit velocities and penetration energies. We also find that the underlying mechanisms contributing to this improvement include enhanced fibril sliding, intralayer and interlayer crack bridging, and crack twisting in the thickness direction enabled by the DFB architecture. Our results show that by combining Bouligand and staggered structures in NFC films, their potential for protective applications can be further improved. Our findings can provide practical guidelines for the design of protective films made of nanofibrils.

Molecular dynamics study on the thermal conductivity and ballistic resistance of twisted graphene

The twist as a new degree of freedom induces several angle dependent properties in twisted graphene, such as electronic and optical properties. However, the ballistic resistance and thermal conductivity of twisted graphene remain not well understood and experimentally challenging. Therefore, the effect of interlayer twist angle on the thermal conductivity and ballistic resistance of bilayer graphene (BLG) has been explored using molecular dynamics simulation herein. Results show that the thermal conductivity of graphene is very sensitive to the twist angle of the interlayer plane. As the twist angle increases from 0° to 60°, the in-plane thermal conductivity of twisted bilayer graphene (t-BLG) first decreases and then increases with a periodic interval of 30°, exhibiting an asymmetric double V-shaped curve. And the cross-plane thermal conductivity of t-BLG gradually first decreases from 0° to 30° and then increases from 30° to 60°, also showing an asymmetric V-shaped curve. In contrast, the interlayer twist angle has a limited influence on the ballistic resistance of t-BLG. With the change of the twist angle, the ballistic limit velocity does not change much, and the fluctuation range is less than 1.56%; the relative kinetic energy also changes little with the fluctuation less than 4%. Such a slight difference is insufficient to make a significant change in its ballistic resistance and its impact resistance is mainly affected by the number of membrane layers. Each additional layer increases its ballistic limit speed by about 8%. This study will provide some theoretical guidance for the study of heat dissipation in the anti-ballistic process of twisted graphene and the design of advanced protective materials.

Improved ballistic limit velocity from filament-wound fibres as composite cover on ceramic tiles

Hard armour plates are used in body armour for protection against high-velocity threats. The strike face often consists of a single ceramic tile that is covered by a sheet material made of a high-tenacity fibre-composite material. During impact, the ceramic will fracture but at the same time cause erosion and fragmentation of the hard core of the projectile. The composite cover is there to improve the ballistic performance by partly maintaining the integrity of the fracturing ceramic. In this study, a new production method where glass fibre yarns were filament-wound around an alumina tile in a unidirectional 0°/90°lay-up, was investigated. Ballistic testing was conducted with a 7.62 mm armour piercing projectile. The new target design gave a remarkable increase in the V50ballistic limit velocity by as much as 16% compared to a traditional design where a glass fibre fabric was wrapped around the tile. A higher degree of fragmentation of the projectile steel core after perforation was also observed. The high degree of fibre alignment in the filament-wound composite, as opposed to the more wavy fibres in the fabric, is believed to be the main reason for the higher ballistic performance.

Numerical Analysis of the Impact Resistance of Composite A-Shaped Sandwich Structures.

This paper focuses on the finite element analysis simulation of the impact properties of composite sandwich structures made of carbon fiber-reinforced polymer lamina. In the existing studies, the composite sandwich structures with A-shaped cores have superior mechanical properties under quasi-static plane compression loads compared to W-shaped, Y-shaped, and X-shaped cores. However, there is limited research on the impact resistance of this structure. This paper studied the resistance of a composite A-shaped core structure to ballistic impact. Using ABAQUS/explicit finite element analysis software, ballistic impact tests for the composite A-shaped core structure were simulated based on the Hashin and Yeh failure criteria with a progressive damage model introduced in the user-defined subroutine VUMAT. First, the composite Y-shaped core sandwich structure was verified via experiments and simulations to determine the accuracy of the method, and then the composite A-shaped sandwich structure was subjected to a series of ballistic impact simulations. With varied impact velocity, the damage to the front and rear face sheet and cores via ballistic loads was simulated to illustrate the overall dynamic response process of the sandwich structure. Subsequently, a curve was fitted using a ballistic limit velocity equation, which was used as the criterion to evaluate the impact resistance of the composite A-shaped core structure. The results showed that, under the same relative density and the same number of component layers, the ballistic limit velocity of the composite A-shaped core sandwich structure was bigger than the composite Y-shaped core sandwich structure. The composite A-shaped core structure had 12.23% higher ballistic limit velocity than the composite Y-shaped core, indicating the impact resistance capabilities of the A-shaped core structure. In addition, the impact location's effect on the impact response was investigated.