Ballistic Limit Velocity Research Articles

Projectile nose-length effect on specific cavitation energy and ballistic limit velocity and thickness

The perforation of armour plates by quasi-rigid projectiles in ductile hole growth has been demonstrated to be influenced by the ratio of plate thickness to projectile diameter, referred to as the hole slenderness ratio, h/D. Here we propose a new non-dimensional geometric ratio, termed as the target containment ratio, that uses the projectile nose-length in place of the diameter, i.e., h/L. We demonstrate that the hole slenderness ratio is a special approximation of the target containment ratio for projectiles with a nose-shape ratio (projectile nose-length normalised by projectile shank radius) on the order of 3. We validate the proposed relationship via a comprehensive numerical study and through comparison with experimental data for the 14.5 mm BS41 armour piercing bullet, for which the nose-shape ratio is about 2. We show that the new target containment ratio dependent formulation of the specific cavitation energy improves the accuracy of the model suggested in Masri and Ryan (2024). This new formulation is also used to update existing formulae for ballistic limit predictions of monolithic and multilayer ductile targets.

Experimental and numerical study on ballistic impact behavior of explosively-welded double-layered Weldox700E targets against ogival-nosed projectiles

In this work, explosive welding technique was used to fabricate 2 mm + 2 mm thick double layered Weldox700E steel targets. The bonding interface exhibited wave-shaped patterns without obvious micro-defects, grain refinement and grain elongation were observed. With specially designed shear specimen and tensile specimen, Ultimate stresses of the bonding interface under shear and tensile loadings were measured to be 526 MPa and 683 MPa, respectively. Ballistic impact tests against ogival-nosed projectiles were conducted on both explosively welded double-layered targets and double-layered contact targets. Ballistic limit velocities of the two target configurations were respectively 225.32 m/s and 203.98 m/s , with the former being 10.5 % higher than the latter. For both target configurations, localized bulging and petal-shaped cracking were observed; specially, welded bonding interface remains well bonded even after perforation of the projectile. Combining experimental results and numerical simulations, it was found that the explosively welded double-layered targets exhibited better ballistic performance than double-layered contact ones. The good welded bonding interface provides a better overall deformation capability for the explosively welded double-layered target, which is an important reason for the improved ballistic performance of the target. Although hardness tests show that there is a significant hardened layer in the explosively welded double-layered target, and the hardness value can reach up to 409.4 HV. However, the thin hardened layer cannot significantly improve the ballistic performance of the explosively welded double-layered target in the high-speed impact process of the projectile.

Experimental and numerical study on CuO/ZnO-modified aramid fabric for ballistic and UV radiation protection

Aramid fabrics are widely used in bulletproof armor because of their excellent mechanical properties. Previous studies have shown that ultraviolet radiation has a negative effect on the mechanical properties of aramid yarn, so improving the mechanical properties and impact resistance of aramid fabrics under ultraviolet radiation has become a research focus. In this work, aramid fabric was modified with CuO and ZnO particles to improve its ballistic performance under ultraviolet radiation. The ballistic impact resistance response and microscopic failure mechanisms of aramid fabrics under ultraviolet radiation were analyzed in detail. Under ultraviolet radiation, the ballistic limit velocity (vbl) of the CuO/ZnO-modified aramid fabric was 185.1 % greater than that of a neat fabric with a similar areal density. The vbl of the single-layer modified fabric was 45.6 % greater than that of the two-layer neat fabrics. The decrease in the ballistic performance of the aramid fabric under ultraviolet radiation was attributed to surface damage caused by the fracture of the chemical structure of the fibers, which weakened the mechanical properties of the fabric. The numerical simulation results were highly consistent with the ballistic impact test results, and the error between the numerical simulation and experimental results was within 10 %. The effects of changes in the mechanical parameters of the fabrics on the protection mechanism and energy absorption structure during ballistic impact were investigated. The energy dissipation of the modified fabric was at least 147.7 % greater than that of the neat fabric, further explaining the significant improvement in the ballistic performance of CuO/ZnO-modified fabrics under ultraviolet radiation.

Experimental and numerical analysis of ballistic impat and material characterization of GFRP and Kevlar 29/epoxy composite laminate

Through experimental testing and numerical simulations, this study examines the effects of ballistic events on thin FRP composite laminated plates fabricated using a hand lay-up method. Experimental ballistic impact tests using a pneumatic gun are conducted on composite plates reinforced with woven glass and woven Kevlar 29 fibers. An advanced three-dimensional finite element model programed in Ansys/Autodyn v19.1 is employed to verify the experimental findings and analyze the ballistic perforation characteristics of the target. The crucial material constants needed for the constitutive material model used in the simulation are acquired through precise experimentation on samples prepared from the fabricated laminates. Significant agreement is observed between the FE simulations and experimental findings, particularly concerning the assessment of residual velocities of the projectile and damage pattern in the laminates. The results of this study show that when subjected to ballistic impact by a flat-ended cylindrical projectile, the thin woven FRP composite primarily experiences damage characterized by delamination, fiber breakage and matrix cracking. Additionally, based on current simulations, it is observed that the ballistic limit velocity of the Kevlar 29/epoxy laminate exceeds that of GFRP by 25.64% when both materials have an equal thickness of 2.8 mm.

Mechanism of pre-tension on the impact response of plain weave fabric: Experimental and numerical investigation

The fabrics made of high strength and toughness fibers are increasingly used in the structural and individual protection. The research on energy dissipation mechanism and the improvement methods for improving energy dissipation of the fabric under impact, as well as the change of ballistic limit velocity under pre-stress, is relatively mature. However, the transmission mode and velocity of transverse wave in the fabric, as well as the method of accurate finite element simulation is still lacking. In this paper, the transverse impact response of ultra high molecular weight polyethylene (UHMWPE) fabric subjected to fragment impact is studied experimentally and numerically. A novel biaxial pre-tension fixture was developed, and fragment impact test of the fabric in pre-tension state was realized using a gas gun. The displacement-time history of each point on the fabric in three-dimensional space was characterized through 3-D DIC technology, and the process of transverse wave transmission on the fabric after fragment impact was obtained. The calculated results of the finite element model established by truss element agrees reasonably well with the experimental results. The experimental and numerical results indicate that the impact velocity of fragment affects the velocity of transverse wave in the fabric, but does not change its transmission mode. With the increase of pre-tension amount, the propagation mode changes from a cross shape to a rhombic shape and finally to a circular shape, and the wave velocity increases greatly. The wave transmission process in yarns at a mesoscopic level was analyzed through finite element simulation, and the transmission path was determined. It was found that pre-tension accelerated the wave velocity on the stepwise path, causing the transverse wave to reach a farther position in the diagonal direction of the fabric, resulting in different modes of wave transmission. The research content may provide more ways for the application of fabrics in protection.

Mechanical behavior of GFRP-Polymer sandwich composites with montmorillonite nanoclay

Abstract A sandwich composite consists of high stiffness and high strength outer layers called face sheets and low-density inner layers called core. In the present study, the sandwich composites comprising glass fabric/epoxy face sheets and epoxy modified with montmorillonite (MMT) nanoclay core are fabricated by a co-curing method. The sandwich panels show higher static tensile and three-point flexural properties such as ultimate strength, elastic modulus, and failure strain on adding up to 3 wt.% of MMT nanoclay contents than pristine sample. The former properties reduce at 4 and 5 wt.% of nanoclay contents owing to the formation of clustering of clay particles within the matrix. The stress-strain behavior of sandwich panels with 0–5 wt.% of MMT nanoclays obtained by laminated plate model follows experiments. The maximum lateral deflection of sandwich panels with nanoclays predicted by assuming them to be a simply supported beam is in-line with experimental results. For low-velocity single impact perforation load, the maximum force of sandwich panels improves on the infusion of up to 3 wt.% of clay while maximum displacement decreases. The ballistic limit velocity and energy absorption of panels improve on adding up to 3 wt.% of clay. Beyond the ballistic limit at different initial velocities, the residual velocity of sandwich panels decreases on addition of up to 3 wt.% of clay and energy absorption increases.

A combination strategy of strengthening for enhancing impact-resistance property in high entropy alloys

Developing new high-entropy alloy system has been a subject of significant research interest in recent years. However, it is a challenge to enhance the impact-resistance property in existing high-entropy alloys. Here we proposed a combination strategy of strengthening via second phase and grain refining to build a network microstructure in Co2Ni2CrVTa0.3 high entropy alloys that could significantly enhance the ballistic limit velocity from 407.8 m/s to 435.4 m/s. Especially, under a high impact velocity of 750 m/s, the energy absorption of the alloy was evidently larger than that of the Ta-free alloy. The microstructure of Co2Ni2CrVTax alloys could be sensitively tuned via Ta addition because of the Ta-induced multi-scale microstructure involving the micro-scale Laves phase and nano-scale L12 structure precipitates. This should be the structural mechanism of the enhanced impact-resistance property, and will shed light on the development of alloys with excellent impact-resistance property.

Determination of ballistic resistance model of finite thickness material based on Artificial Neural Network

Ballistic resistance behavior of finite thickness material is affected by factors of target thickness, projectile nose shape, and impact angle. The widely used ballistic limit velocity (BLV) model can only reflect the ballistic resistance behavior of a target in a single given impact scenario. The collected BLV from different impact scenarios can only partially reflect the effect of those factors on the ballistic resistance. A general model of BLV considering these factors simultaneously is desired.In this study, numerical impact models are first verified by a significant number of experiments. A guided random sampling method is proposed to collect numerical BLV data for training/validating usage. BLV data from experiments and simulations are then assembled by this method and subsequently trained by Artificial Neural Network (ANN). k-Folder Cross Validation (K-CV) technique designed for evaluating small sample training network is introduced to validate and test the network. The ANN-predicted results are decomposed by proper singular value decomposition methods. It is found that the Rank-1 decomposition results (with highest singular value) can fully reveal the decoupled relationship between BLV and its independent factors (MAPE < 6 %), with which analytical ballistic models are established. The results show that our proposed model can quantitatively describe the fully decoupled effect of target thickness, impact angle and projectile nose shape on the BLV with high accuracy.

High-speed perforation of IN718 plates by spherical TC4 Ti alloy projectiles: Experiments and modeling

Data and knowledge on ballistic performance of Inconel-718 (IN718) alloy is critical for evaluating the resistance of turbine blades against foreign object impacts in aeronautical and astronautical industries. Ballistic perforation experiments (impact velocity 480 ms−1 to 1340 ms−1) with TC4 spherical projectiles (5-mm-diameter) are conducted on IN718 target plates (2-mm-thick) in this work, along with high-speed photography. The IN718 plates show multiple deformation and failure modes (bulging, dishing, petaling and plugging). The ballistic limit velocity for the investigated projectile/target combination is 823 ms−1. Postmortem material characterizations (optical photography, scanned electron microscopy and energy dispersive spectrometry) are conducted on recovered projectiles and bullet hole inner walls, and the observations indicate adiabatic shearing, surface melting and abrasion of projectile material. A finite element model based on the Johnson–Cook constitutive model and failure criterion is established, and reproduces the ballistic experiments. Dimensionless analyses are conducted on the dimensions of postmortem projectiles and bullet holes, and the projectile residual velocity/mass. On the basis of experimental observations and theoretical analysis of the projectile dynamics, the whole perforation process is divided into three stages (the entering, cratering and plugging stages). A multi-stage analytical model on perforation is then developed considering the effects of cavity expansion, projectile deformation and abrasion, and can well predict the projectile dynamics during entering and cratering stages.

Oblique penetration of spherical tungsten alloy projectiles on high-strength steel plates

The uniaxial tensile and dynamic compression properties of 22SiMn2TiB high-strength steel were first investigated, which shows certain strain-rate effects and obvious temperature-softening effects. Ballistic tests were carried out on 12 mm thick 22SiMn2TiB steel using ∅11 mm tungsten projectiles at 0°∼45° obliquity and a velocity of 500∼900 m/s. The study found that the ballistic limit velocity (BLV) increased monotonously with the increase of the obliquity. Based on the De Marre equation, a BLV calculation model was calibrated, which predicted experimental results well. Corresponding numerical simulation was carried out using LS-DYNA with fitted Johnson-Cook model parameters, its results are in good agreement with the test's. Additionally, the protective mechanism of the 22SiMn2TiB steel plate at an oblique angle was revealed through microscopic morphology analysis of the high-strength steel plate. It identifies adiabatic and normal shear failure, tensile and tensile-shear mixed failure, and the formation of different cracks in two groups, ultimately leading to plugging failure. The study provides a reference for the engineering design of the defensive structures using 22SiMn2TiB high-strength steel.

The impact of the coupling relationship between projectile size and yarn dimension on the ballistic performance of plain weave fabric

Aramid fibers, due to their relatively high inter-yarn friction, high strength, high modulus, and other characteristics, have become a typical representative of flexible anti-ballistic materials in modern warfare. Current research on the anti-penetration of aramid fabrics mostly focuses unilaterally on the structure and performance of aramid fabrics or the shape and size of projectiles, with fewer studies on the coupled effect of both on ballistic performance. This study analyzes how the coupling relationship (or size effect) between the projectile and fiber bundle dimensions affects the fabric ballistic performance from a mesoscopic scale perspective. Taking plain weave aramid fabric as the research object, considering different diameter projectiles, through a large number of ballistic impact tests and numerical simulations, parameters such as ballistic limit velocity, average energy absorption of fabric, and specific energy absorption ratio (average energy absorption of fabric divided by projectile cross-sectional area) are obtained for ballistic performance analysis. The influence law of projectile size on the ballistic performance of high-performance fabrics is as follows: The relative range of fitted ballistic limit velocity at different target positions gradually decreases and then stabilizes as the projectile diameter increases, indicating that the fabric structure effect gradually disappears at a projectile diameter of 12 mm; The average ballistic limit velocity at three impact positions, P1, P2, and P3, provides the corresponding ballistic limit velocity for 1000D aramid fabric, which increases with projectile diameter but the rate of increase slows down at an inflection point, which in this study occurs where the fabric structure effect nearly disappears at a projectile diameter of 12 mm; The energy absorption ratio increases and then decreases as the projectile diameter increases from 4 mm to 20 mm, reaching a peak at the diameter of 12 mm due to the gradual disappearance of the fabric structural effect. The projectile diameter of 12 mm corresponds to the coupling size of 11.159, which provides a size design reference for the macroscopic-based continuum models of aramid plain weave fabrics.

Perforating characters of Zr-based bulk metallic glass fragment against thin steel target

To investigate the perforating characteristics of Zr-based bulk metallic glass fragments against thin steel target, ballistic experiments were carried out to measure ballistic the limit velocities of fragments perforating against different thicknesses of targets. The fragments were driven by a 57 mm one-stage light gas gun to impact the thin steel target. The numerical model of Zr-based bulk metallic glass fragments perforating against thin steel target was established using Autodyn2D commercial software, and the perforating process and perforating mechanism were analyzed by numerical simulation. The semi-empirical model to predict the ballistic limit velocity was fitted. An energy model for calculating the residual velocity of a fragment was derived based on the conservation of energy. The theoretical results of the semi-empirical model and the energy model are in good agreement with experiment results and simulation results. And the energy model has good applicability without fitting the parameters for different target thicknesses.

Study on bulletproof performance of functionalized fabrics modified by microcapsules

AbstractThe incorporation of microcapsule particles (MPs) into fabrics offers the potential to enhance both the friction between fabric yarns and the bulletproof impact performance. In this study, MPs were prepared using the interfacial polymerization method. Furthermore, an innovative modification of the AF fabric was achieved by introducing a silane coupling agent and MPs. This resulted in the development of a microcapsules‐aramid fibers (MPs‐AF) composite material exhibiting excellent protective performance. The characterization experiment demonstrated the successful adhesion of MPs to the AF fabric, forming a robust bond between the fiber and the particles. Importantly, the modification process did not have any adverse effects on the fiber structure. The study further investigated the ballistic performance and protection mechanism of the modified fabrics through mechanical performance tests and ballistic impact tests. The yarn pull‐out experiment revealed that the MPs‐AF composite material exhibited a significant increase in pull‐out force, with a remarkable improvement of 175.6% compared to AF fabric. In the ballistic impact experiments, the MPs‐AF composite material demonstrated a substantial increase in ballistic limit velocity, rising from 52 to 118 m/s when compared to the AF fabric. These findings highlight the potential application of the MPs‐AF composite material in the field of wearable protection.Highlights Fiber surface modification grafting reaction. A simple and novel solution impregnation method was used to prepare modified AF. Preparation of microcapsule particles by interfacial polymerization. Green new fiber bulletproof material. Chemical grafting produces strong chemical bonds to increase interfacial resistance.

Ballistic performance of thin CFRP laminates under complex in-plane preload

In this research, we explore the effects of complex in-plane quasi-static loads on the high-velocity impact response of Carbon Fiber Reinforced Plastic (CFRP) composite laminates, grounded in the practical context of various working loads combined with potential high-velocity impacts experienced by aircraft. The specific complex in-plane loads studied include uniaxial tension and compression, biaxial tension and compression, and a combination of tension and compression preloading. The results show that the complexity of in-plane preloads, along with pre-compression, reduces the ballistic limit velocity. Biaxial preloading, especially in compression, greatly compromises the specimen's ballistic resistance. The study also proposes a theoretical model based on energy conservation principles to predict the ballistic limit velocity of CFRP laminates under various preloading conditions. The research provides valuable insights for designing composite structures and highlights the importance of considering in-plane preloads in assessing thin CFRP ability to withstand ballistic impacts.

Influence of clamping methods on the ballistic performance of 3D shallow straight-joint woven fabrics

The interlaminar strength and designability of three-dimensional shallow straight-joint woven fabrics make them a promising material for personal protective armor. This study investigated the influence of clamping methods on the ballistic mechanism of three-dimensional shallow straight-joint woven fabrics. The study used a mesoscopic yarn-level full-size model developed based on the finite element method to analyze the energy absorption patterns, back face deformation, and damage morphology of the three-dimensional shallow straight-joint woven fabrics under different clamping methods. The results show that the clamping method has a significant influence on the ballistic performance of the fabric. With the weft-sides clamped, its ballistic limit velocity and failure morphology are similar to four-sides clamping, with more negligible energy absorption and failure area. Warp-sides clamped is second, while the corner held undergoes the maximum out-of-plane displacement and energy absorption, exhibiting an utterly different failure mechanism. This study shows that the clamping method of a fabric affects its ballistic performance through interaction with the fabric’s internal structure.

Penetration mechanics of rigid projectiles impacting metallic and concrete targets—A summary of our work

The physical mechanisms operating during the penetration and perforation of metallic and concrete targets by rigid projectiles are reviewed in this paper. The review covers our approach to these phenomena, as detailed in several papers that were published during the last decade. This approach is based on experimental data and their numerical simulations, through which we constructed analytical expressions for the penetration depths and the ballistic limit velocities of the corresponding projectile/target pairs. This review article will benefit researchers in the terminal ballistics community because it presents a full picture of our approach to the subject, and it also outlines the development in our thinking over the years.

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.