Ballistic Limit Velocity Research Articles

Ballistic impact analyses of foam-filled double-arrow auxetic structure

In present study, the foam-filled composite double-arrow auxetic structures were obtained by the mold hot pressing method, bonding technology and stirring foaming process. The ballistic impact tests of the foam-filled composite double-arrow auxetic structure were carried out, and the effect of foam filling on the ballistic impact response of the composite double-arrow auxetic structure was analyzed. The ballistic impact test results indicated that the ballistic limit velocity of the foam-filled double-arrow auxetic structure with the relative density of 16.66% was 121.30 m/s. With the increase of the incident kinetic energy of the projectile, the specific energy absorption of the foam-filled auxetic structure increased first and then decreased, and remained near the horizontal line of 550 J/kg at last. Compared to unfilled auxetic structure, the ballistic limit velocity of foam-filled auxetic structure increased by 6.12% and the energy absorption property of foam-filled auxetic structure was improved. The ballistic impact performances of foam-filled composite double-arrow auxetic structures were studied by finite element method. The simulation results of foam-filled auxetic structure with RD=16.66% were in good agreement with the experimental results. The simulation results demonstrated that the ballistic limit velocities of foam-filled composite auxetic structures with relative densities of 9.08%, 16.66% and 23.06% were 86.74 m/s, 120.60 m/s and 152.80 m/s, respectively. Furthermore, the increase of relative density had a positive effect on improving the anti-penetration performance of foam-filled composite auxetic structures.

Ballistic performance and protection mechanism of aramid fabric modified with polyethylene and graphene

Aramid fabric has been widely used as a bulletproof material due to its lightness and comfort. However, multiple fabric layers must be used in one body armour, inevitably reducing its flexibility. To improve the ballistic performance of single-layer aramid fabric, we innovatively modify the fabric with polyethylene (LDPE) and graphene/polyethylene (GR/LDPE). Based on mechanical property tests, ballistic impact test and finite element analysis (FEA), the ballistic behaviours and key mechanism of modified fabrics are revealed. Experimental results show that LDPE or GR/LDPE modification does not change the tensile strength and Young's modulus much, but it greatly improves the interyarn friction of fabric. This improvement in the interyarn friction leads to twice ballistic limit velocities of pure aramid fabric; the ballistic limit velocities of pure, LDPE and GR/LDPE aramid fabrics are 105 m/s, 223 m/s and 216 m/s, respectively. However, excessive friction causes negative effects, which is why GR/LDPE/aramid fabric is weaker than LDPE/aramid fabric. The FEA results show that fabric motion and deformation are the main ways to resist impact as they absorb over 85% of the dissipated kinetic energy of the projectile. The novel modification method could be applied to the manufacturing of lightweight and effective body armour.

Polyimide aerogels for ballistic impact protection

The ballistic performance of edge-clamped monolithic polyimide aerogel blocks (12 mm thickness) has been studied through a series of impact tests using a helium-filled gas gun connected to a vacuum chamber and a spherical steel projectile (approximately 3 mm diameter) with an impact velocity range of 150–1300 m s−1. The aerogels had an average bulk density of 0.17 g cm−3 with high porosity of approximately 88%. The ballistic limit velocity of the aerogels was estimated to be in the range of 175–179 m s−1. Moreover, the aerogels showed a robust ballistic energy absorption performance (e.g., at the impact velocity of 1283 m s−1 at least 18% of the impact energy was absorbed). At low impact velocities, the aerogels failed by ductile hole enlargement followed by a tensile failure. By contrast, at high impact velocities, the aerogels failed through an adiabatic shearing process. Given the substantially robust ballistic performance, the polyimide aerogels have a potential to combat multiple constraints such as cost, weight, and volume restrictions in aeronautical and aerospace applications with high blast resistance and ballistic performance requirements such as in stuffed Whipple shields for orbital debris containment application.

Experimental and numerical study on the ballistic impact resistance of the CFRP sandwich panel with the X-frame cores

Fiber reinforced composite sandwich structures have wide applications in reducing the weight of high-speed aircrafts due to their processibility and high specific performance. It is of great significance for the safety to study the failure mechanism of composite sandwich structures under the ballistic impact and improve the structural impact resistance. However, the previous researches mainly focus on the performance of the hybrid sandwich structures with foam cores or metal grid cores. The main novelty of this study is to investigate the ballistic impact resistance of a composite composite sandwich panel with the fiber reinforced X-frame cores by using the projectile impact tests and numerical simulations. The impact resistance of this integrally molded fiber reinforced cores is less reported and is expected to be superior than that of the common aluminum, polymer and foam cores. For comparison, the carbon fiber composite cross-ply laminates with the identical areal density and the foam reinforced sandwich panels with the X-frame are tested. The experimental results indicate that the ballistic limit of the X-frame sandwich panel is similar to that of its equivalent laminate under the normal projectile penetration. Filling foams increase the structural ballistic limit velocity and energy absorbing amount by 18.2% and 33.9%, respectively. The widest range of fiber breakage and delamination on the sandwich panel observed appear at impact velocities approaching the ballistic limit, while the local damage is found under the high-speed perforation. The numerical results indicate that the projectile kinetic energy dissipated by the X-frame core accounts for over 50% of the total under the normal impact and the core has the better specific energy absorption capacity than the skins. The impact oblique angle and impact position are found to have a significant effect on the impact resistance of the X-frame sandwich panel through the numerical calculations.

Effect of baffles on hydrodynamic ram and damage of storage tank under fragment impact

PurposeFragment impact is one of the main threats for the safety of storage tank in aircraft. This study aims to investigate the influence of inserted baffle on hydrodynamic ram (HRAM) and damage of storage tank to optimize the protective performance of storage tank under fragment impact.Design/methodology/approachThe characteristics of initial shock wave, cavity evolution, velocity attenuation of fragment and anti-penetration performance of baffle-inserted tanks were evaluated by experimental and numerical methods.FindingsResults indicated that the inserted baffle in tank could significantly increase the velocity attenuation rate of fragment in water. The volume of the second cavity caused by the inserted baffle rapidly decreased with the baffle position moving backward. For the baffle-inserted tank, the deformation of the front and rear walls was substantially weakened, and the alleviating effect for front wall was more significant. Comparing with the ordinary storage tank, the inserted baffle at normalized position 0.25, 0.5 and 0.75 in tank made the ballistic limit velocity of storage tank increasing by 118.3%, 20.0% and 54.0%, respectively.Originality/valueThe findings of this work illustrating the HRAM history and damage map of storage tanks after inserted baffle could provide a convenient approach to improve the anti-penetration performance of storage tanks effectively.

A novel design of hybrid ceramic composite plate under ballistic impact

To increase safety and enhance the armor plate's ballistic performance, an advanced hybrid ceramic composite plate design is being investigated. The ballistic limits and safety levels were significantly improved by the hybridization of ceramic materials. In this present study, three different types of ceramic plates were modeled using the finite element (FE) software with a subroutine to define user material model (VUMAT) code and determine the ballistic behavior of the body armors for défense industries. The significant improvement of the ballistic limit velocities of the B8K8 panel and SB2K2 panel are investigated that the 416 m/s and 606 m/s, respectively.

Predictions on multi-class terminal ballistics datasets using conditional Generative Adversarial Networks

Ballistic impacts are a primary risk in both civil and military defence applications, where successfully predicting the dynamic response of a material or structure to impact crucial to the design of safe and fit-for-purpose protective structures. This study proposes a conditional Generative Adversarial Network (cGAN) architecture that can learn directly from available ballistic data and can be conditioned on additional information, such as class labels, to govern its output. A single Multi-Layer Perceptron (MLP) cGAN architecture is trained on a multi-class ballistic training set consisting of 10 classes labelled 0−9 where each class refers to a ballistic curve with a different ballistic limit velocity, vbl. A total of 5 models are trained on datasets consisting of 5, 10, 15, 20 and 25 samples within each class. For integer class labels 0−9, all cGAN models successfully predict the vbl with a maximum error of 4.12%. Additionally, for non-integer class labels between 0−9 the vbl predictions are similar despite not explicitly appearing in the training set. Moreover, each cGAN model is challenged to generate new samples for class labels that exist beyond the scope of the training set for class labels between 9−20. Four of the models predict the vbl with an error of less than 1.5% in all cases. This study showcases how a cGAN model can learn directly from a multi-class ballistic dataset and generate additional samples representative of that data for classes that do not appear explicitly in the training set.

Strain rate effect analysis of hybrid composites under the high-velocity impact

In this paper, the damage behavior of fiber metal laminate (FML) is studied under high-velocity impact (HVI) at different strain rates (1 s−1, 100 s−1, and 1000 s−1) for flat, hemisphere, and sharp nosed projectiles. A finite element model has been used to examine the damage modes and failure processes of carbon fiber reinforced aluminium laminates (CRALLs) under HVI. This study is based on continuum damage mechanics. The damage criteria for aluminium (Al) and carbon fiber composite layers are identified by Johnson-Cook (J-C) and Hashin damage models, respectively. To analyse the inter-laminar de-lamination caused by the HVI, a cohesive surface regulated by bi-linear traction-separation is applied. The CRALL ballistic limit is analysed for different projectiles, which strike at initial velocity ranges from 60 m/s to 150 m/s to the CRALL. The obtained numerical results are in good agreement with the literature experimental results, which indicates the model is permissible for further analysis. The obtained results show that if strain rate varies from 1 s−1 to 1000 s−1 then CRALL ballistic limit velocity increases for all projectiles. The CRALL ballistic limit is the highest for flat nosed projectiles, followed by hemisphere and sharp nosed projectiles.

Development of a Coated Fabric Armour System of Aramid Fibre and Rubber

Ballistic impact tests were conducted on polymer-coated multi-layer fabric targets using 0.357 SIG projectiles. The effect of fatigue loading on the yarn pull-out force of coated Twaron fabrics was studied for the first time. A validated mesoscale numerical modelling approach was developed to simulate the ballistic impact. The elastomeric coating significantly improved impact resistance. The coating is stable in a wide range of ambient temperatures and performs well upon being subjected to fatigue. A coated target having 6.6% less areal density and 20% less thickness than its neat counterpart has shown similar ballistic limit velocity.

High-velocity projectile impact response of rubber-coated aramid Twaron fabrics

The impact response of aramid Twaron CT709 fabrics thinly coated with a commercially available spray-on rubber material has been studied for the first time. Both neat and rubber-coated fabric targets were subjected to impact using 12 mm, 7.05 g spherical steel projectiles. The impact velocities ranged from 150 to 250 m/s. Each target consisted of three plies of neat or coated fabrics. Residual velocities, impact velocities and transverse deformation profiles were recorded using a high-speed camera, and the mechanism of failure and energy absorption were studied. It was observed that the ballistic limit velocity (BLV) increased by 18% in the rubber-coated specimens compared with neat fabric specimens. A critical velocity (Vc) was established below which the coated targets absorbed higher energy than their neat counterparts. The rubber coating was found to promote a membrane effect with global deformation to failure leading to higher energy absorption than the neat counterparts. However, the coated samples absorbed lower energy for impact velocities greater than Vc. At these velocities, the rubber-coated specimens showed localised failure leading to lower energy absorption than the neat counterparts. A novel numerical modelling approach was proposed to simulate coated fabrics, and the models predicted the BLV with high accuracy (error < 4%).

Experimental Tests and Numerical Simulations on the Ballistic Impact Response of a Highly Inhomogeneous Aluminium Foam.

A sandwich structure is a composite material consisting of thin skins encapsulating a cellular core. Such structures have proven to be excellent energy absorbents and are frequently found in various types of protection. Even so, few studies exist in the open literature on the response of the core material itself under extreme loadings such as blast and impact. Since a blast load is usually accompanied by numerous fragments, it is important to understand and be able to predict the ballistic impact resistance of the often highly inhomogeneous cellular core materials in design. In this study, the ballistic impact response of an aluminium foam with a complex cell structure has been investigated both experimentally and numerically. First, an extensive material test program involving compression tests on cubic specimens loaded in the thickness direction of the foam was carried out to reveal the mechanical properties of the material. In addition, several of the specimens were scanned before testing using X-ray Micro Computed Tomography (XRMCT) to map the multi-scale topology and morphology of the material. These data were later analysed to extract density-variation plots in many different material orientations. Second, ballistic impact tests were conducted using a gas gun where rigid spheres were launched towards aluminium foam plates, and the ballistic limit velocity and curve of the foam material were established. Finally, numerical simulations of both the material tests and the ballistic impact tests were carried out using LS-DYNA and different modelling approaches based on the XRMCT data. It will be shown that, independent of the modelling strategy applied, good agreement between the experimental impact tests and the numerical predictions can be obtained. However, XRMCT data are important if the final goal is to numerically optimise and improve the behaviour of inhomogeneous foams with respect to energy absorption, thermal isolation, or similar properties.

Kinematic Analyses of Metallic Plate Perforation by Penetrators with Various Nose Geometries

This study analyses kinematics of a metallic plate perforation by a penetrator with truncated ogive nose geometry to find solutions also to blunt, conical, ogive, and hemi-spherical nosed penetrators. Plugging, ductile hole enlargement, dishing, and petal forming failure modes are used in the analyses. Acceleration throughout perforation is calculated by using the related failure mode, analytical model, and the target-penetrator interaction geometry. Depending on the failure model; back lip and front lip formation during ductile hole enlargement, plug formation during plugging, and deflection of target plate during dishing is also analysed. Analyses are based on projectile’s equation of motion, momentum and energy equations, and projectile-target plate interactions. The analyses results for selected cases, with the impact velocity range 215-863 m/s, are compared with the test data. The residual velocity estimation for a strike velocity is close to the related test data with an error of 0.3-2.2 %, except for conical nosed penetrators at impact velocities approaching the ballistic limit velocity

An improvement on the Florence analytical equation for predicting the ballistic limit velocity of ceramic–aluminum targets and its development to ceramic–aluminum–polyurea panels

An improvement on the Florence analytical equation for predicting the ballistic limit velocity of ceramic–aluminum targets and its development to ceramic–aluminum–polyurea panels

Molecular dynamics simulation of perforation of graphene under impact by fullerene projectiles

In this paper, molecular dynamics (MD) simulations are employed to study the perforation of graphene under impact by fullerenes of various sizes. The buckling characteristics of fullerenes after impact are classified and discussed. The relative state of C180 projectile and graphene under impact at different velocities is also investigated. We observed that the C180 projectile rebounds at low velocity (V < 4.25 km/s), sticks to graphene at high velocity (4.25 km/s ≤ V ≤ 4.75 km/s), and perforates the graphene at higher velocity (V ≥ 4.75 km/s). It is found that the buckled cap of large-size fullerene formed after impact can better absorb kinetic energy. In addition, different crack modes of graphene after perforation were investigated. The effect of fullerene projectile size and initial velocity on ballistic limit velocity was also clarified. This study provides new implications for the application of large-size fullerenes as impact shields.

Dynamic penetration behaviors of single/multi-layer graphene using nanoprojectile under hypervelocity impact.

Single/multilayer graphene holds great promise in withstanding impact/penetration as ideal protective material. In this work, dynamic penetration behaviors of graphene has been explored using molecular dynamics simulations. The crashworthiness performance of graphene is contingent upon the number of layers and impact velocity. The variables including residual velocity and kinetic energy loss under different layers or different impact velocities have been monitored during the hypervelocity impact. Results show that there exists deviation from the continuum Recht–Ipson and Rosenberg–Dekel models, but these models tend to hold to reasonably predict the ballistic limit velocity of graphene with increasing layers. Besides, fractal theory has been introduced here and proven valid to quantitatively describe the fracture morphology. Furthermore, Forrestal–Warren rigid body model II still can well estimate the depth of penetration of multilayer graphene under a certain range of velocity impact. Finally, one modified model has been proposed to correlate the specific penetration energy with the number of layer and impact velocity.

A parametric study on the behavior of FMLs based on UHMWPE composite under high velocity impact loading

Numerical parametric study is performed to investigate ballistic impact performance of a novel fiber metal laminate (FML) based on ultra-high molecular weight polyethylene (UHMWPE) fiber composite and aluminum 2024-T3 layers. A finite element modeling is developed and validated with experimental tests. A user-defined material subroutine based on continuum damage mechanics is used to define damage constitutive model of UHMWPE composite. High velocity impact simulations shows similar modes of failure to that observed in experiments. The effect of various parameters such as metal thickness, composite core thickness, metal volume fraction (MVF), and lay-up sequence on ballistic limit velocity, absorbed energy and specific perforation energy (SPE) of samples has been investigated. The results show that increasing the number of composite layers increases the SPE while increasing the thickness of metal layers decreases the SPE. Although, as the core thickness increases, the growth of SPE decreases. Changes in the lay-up sequence do not have much effect on ballistic velocity and absorbed energy. Whereas, the MVF is an important parameter in the high velocity impact performance of the PERALL specimens. In addition, with equal MVF, stacking sequence change has no significant effect on the ballistic limit velocity. Finally, a simple linear equation is suggested to describe the relationship between MVF and specific perforation energy.

Dynamic Behavior of Kinetic Projectile Impact on Honeycomb Sandwich Panels and Multi-Layer Plates

In order to study the dynamic response associated with the impact of a kinetic projectile on the internal structure of an artificial satellite, we propose a kinetic projectile configuration with non-metallic material wrapping and multiple damage elements. The artificial satellite is simplified as a honeycomb sandwich panel and multi-layer plates. We carried out a ground damage test and finite element dynamic simulation, and we determined the lateral effect and penetration performance of the projectile. Then, we studied the dynamic behavior of the projectile penetrating the honeycomb sandwich panel using a theoretical model. We found that its ballistic limit velocity was 150 m/s, and the deformation of the opening had little relationship with the projectile velocity. Finally, we studied the dynamic response of the kinetic projectile impacting the multi-layer plates under various launch parameters. We found that the launch velocity required to meet the damage requirements was within 325 ± 25 m/s. Projectiles with a higher initial velocity had a stronger ability to penetrate the plates, but initial velocities higher than 325 m/s led to a reduced damage area. The kinetic projectile could adapt to incident angles less than 5° when damaging the plates. With the increasing incident angle, the penetration ability was reduced, and the damage area increased.

Ballistic Impact of Structural Steels at Low Temperatures

Abstract Steels are usually stronger at low temperatures than at high temperatures. But low temperatures are, particularly in combination with high strain rates and high stress triaxiality ratios, known to cause embrittlement. The common understanding is that the ductility of steels decreases dramatically below a threshold temperature known as the ductile-to-brittle transition temperature. This study explores the ballistic performance of Strenx 960 Plus steel plates at both low temperatures and room temperature. We describe a ballistic setup where target plates were cooled down to as low as −60 °C before we present results from ballistic impact tests with three different projectile types. The ballistic limit velocities from tests at low temperatures were higher than the ballistic limit velocities from tests at room temperature, indicating that brittle fracture does not take place. An analytical approach based on the Johnson–Cook constitutive relation, the Cockcroft–Latham ductile failure criterion, and a simple brittle fracture criterion is presented. The model suggests that ductile fracture prevails for most realistic material state histories, both in the ballistic impact tests as well as for quasi-static and dynamic tensile tests. This supports previous observations that brittle fracture is unlikely to occur in modern steels even when subjected to rapid loading and low temperatures.

Mesoscale modeling of ballistic impact experiments on a single layer of plain weave composite

To gain fundamental understanding of energy absorbing mechanisms during high velocity impact of plain weave S-2 glass/epoxy composites, single layer composites are ballistically tested and modeled. To avoid boundary condition effects, targets were 0.6 m by 0.6 m with free boundaries. Targets were perforated by 17 grain, 0.22 caliber fragment simulating projectiles . Experiments focused on determining ballistic limit velocity and the associated damage modes. The experiments were simulated with a continuum finite element model with effective plain weave properties that predicted the ballistic limit velocity with 6% error. A mesoscale model that incorporates the woven fabric architecture and lower length scale energy absorbing mechanisms was also developed. The mesoscale model includes accurate geometry and fiber volume fraction , rate-dependent matrix behavior, and important damage mechanisms including tow-tow delamination , tow pullout and frictional sliding . The mesoscale model predicted ballistic limit velocity with 1% error and more accurately predicts the deformation modes during ballistic impact and penetration than the continuum modeling approach. The mesoscale model indicated two phases of penetration, the first dominated by momentum transfer and the second dominated by tow tension and pullout. In a materials-by-design framework, the mesoscale model was used to quantify energy dissipation and identify important damage mechanisms that could be optimized to provide improved ballistic penetration resistance .

Ballistic performance of a lightweight nacre-inspired armour panel – a numerical study

This paper provides a numerical investigation on the ballistic performance of ceramic composite armour panels with porous architectures inspired by nacre from mollusc shells. The development of such armour panels can lead to reduced weight and improve ballistic performance through projectile rotation induced by non-uniform contact stresses. The porous tablets of nacre have the potential to reduce the mass of armour panels without compromising their ballistic performance. Preliminary simulations were conducted to assess the performance of several porous bio-inspired structures that have the potential to survive projectile impact with less mass. Several bio-inspired panels composed of various porous designs were generated based on the different void architectures of nacre's tablets. Their performances were benchmarked against a monolithic panel under the same projectile impact condition and having the same 4.5 mm overall panel thickness but higher mass. It was found that for the cases considered, the biomimetic panels with porous architectures possess better ballistic performance compared to the corresponding monolithic panel by arresting the projectile having an initial impact velocity of 500 m/s, whilst reducing its mass by up to 18%. A further study was conducted on bio-inspired panels with a higher thickness but the same mass as the solid monolithic panel under the same projectile impact condition. It was found that the bio-inspired panel exhibits significantly improved ballistic performance when subjected to a fragment simulating projectile having an initial velocity chosen to be the ballistic limit velocity of the corresponding monolithic panel.