Projectile Nose Research Articles

Ballistic performance of alumina/carbon fiber/aramid composite against impact of different projectile shapes

This study explores the ballistic performance of an alumina/carbon fibre/KevlarⓇ aramid composite panel against impacts from various projectile shapes, including ogive, conical, cylindrical, hemispherical, and 5.56 mm × 45 mm NATO rounds. The aim is to analyse the influence of projectile nose shape on penetration resistance and energy absorption, critical for defence and aerospace applications. Numerical simulations carried out in LS-DYNAⓇ, validated by experimental data, reveal that the ceramic layer effectively initiates projectile deceleration, while the fabric layers absorb the majority of the kinetic energy. Hemispherical projectiles exhibit minimal plastic deformation, highlighting the composite's optimal performance against this shape. In contrast, ogive projectiles demonstrate greater penetrative potential, challenging the composite's multi-layered defence. The study finds that approximately 90% of the kinetic energy is absorbed by the fabric backing, with a small portion absorbed through projectile deformation and ceramic cracking. These results underscore the importance of considering projectile deformation in simulations and suggest that the composite design is well-suited for enhancing protection against high-velocity impacts in defence and aerospace sectors.

The effect of projectile nose shape on the formation and expansion of impact-induced ejecta for sand target

Understanding the ejecting behavior of granular materials under impact conditions is of vital important for the asteroid sampling and defense. During the impact and penetration stages, the interaction between the projectile and the target controls the impact-induced ejecta behavior. However, the correlation between projectile nose shape and the formation and expansion characteristics of the ejecta remains unclear. In this study, a vertical launch system and high-speed camera were used to carry out the experiments of projectile impact on sand target at 100 m/s. The variations of ejecta parameters induced by different projectile shapes (cone and ogive) and sharpness (cone angles of 30°, 60°, 120°; Caliber-Radius-Head values of 0.5, 1.0, 3.0) were compared. The results showed that both the formation and expansion of the ejecta are influenced by the projectile shape, especially the sharpness of projectile nose. Ejecta parameters such as the emergence time, horizontal expansion velocity, and ejecta mass are positively correlated with the sharpness of projectile nose, while emergence diameter and ejecta angle exhibit a negative correlation. The above observed phenomena are attributed to the energy deposition rate of the projectile on the target during the impact stage and the flow direction of sand grains after the projectile-grain interaction during the penetration stage. These findings can gain an insight into the influence of projectile shape on the ejecting behavior of granular materials. In addition, these findings offer valuable references for the modification of ejecta models that incorporate projectile nose shapes and contribute to the design of impact sampling mechanisms in practical tasks.

Constitutive and impact response of AA7475-T7351 under different projectile shapes and velocities: An experimental and numerical investigation

Through experimental and numerical investigation, this article investigates the constitutive and impact response of the 1.6 mm thick AA7474-T7351 plate under the impact of blunt and hemispherical-nosed projectiles at different velocities. The Johnson-Cook plasticity and failure model parameters were calibrated for the target material using experimental data from the tensile experiments, which took into consideration the effects of plastic strain, strain rate, temperature and stress triaxiality. Further, JC plasticity model parameters were also optimised using a parametric optimisation process. The flow stress of AA7475-T7351 shows positive and negative sensitivity toward loading rate and temperature. It is observed that the ductility of AA7475-T7351 decreases with increases in stress triaxiality, whereas the flow stress increases. Perforation experiments on 1.6 mm thick circular AA7475-T7351 plates were carried out using a single-stage gas gun along with the high-speed Digital Image Correlation (3D-DIC) technique. The blunt nose projectile causes shear failure, whereas hemispherical nose projectile causes combined tension-shear failure; a microscopic study is performed to confirm this phenomenon. Experimental results obtained from DIC were validated using the numerical analysis in the Abaqus/Explicit platform in terms of transient out-of-plane deformation of the target plate. The quantitative error between experimental and numerical analysis was evaluated using the Russell error technique. Numerical analysis revealed that constitutive relations could predict the physical fracture mechanisms during perforation qualitatively as well as quantitatively.

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.

Comparative study of effect of fragment nose shapes on damage characteristics of thin target plate in ballistic applications

Experimental and numerical investigations in ballistic applications have predominantly focused on determining the ballistic limit of target plates for various projectile shapes. However, limited attention has been given to the influence of projectile nose shapes at high impact velocities. To address this gap, 3D FE simulations were carried out on a 1 mm thin target plate using J-C material model, the Gruneisen equation of state (EOS), an erosion contact algorithm, and the explicit FE code LS-DYNA. The simulations involved impact of fragments of equal mass but different nose shapes. The results revealed a significant influence of fragment shape on both the ballistic limit and overall plastic deformation of the target plate. Particularly, the target plate impacted by a hexagonal pyramid fragment shape exhibited the highest ballistic limit and global plastic deformation. Further, it was also observed that at higher impact velocities, the former fragment shape caused the maximum damage to the target plate, while at lower impact velocities, the cubical fragment shape demonstrated the highest lethality. This difference in target damage is known to be governed by the energy required to erode the target and fragment material. The results from the current study offers valuable insights into how different fragment shapes influence the damage inflicted on target plates in ballistic scenarios. The findings presented in this study also offer guidance on selecting suitable fragment shapes for future use in Fragment Generator Warheads (FGW) in order to maximize the damage or lethality inflicted on targets.

Failure pattern in ceramic metallic target under ballistic impact

The ballistic resistance and failure pattern of a bi-layer alumina 99.5% - aluminium alloy 1100-H12 target against steel 4340 ogival nosed projectile has been explored in the present experimental cum numerical study. In the experimental investigation, damage induced in the ceramic layer has been quantified in terms of number of cracks developed and failure zone dimensions. The resultant damage in the backing layer has been studied with variation in the bulge and perforation hole in the backing layer with the varying incidence velocity. The discussion of the experimental results has been further followed by three dimensional finite element computations using ABAQUS/Explicit finite code to investigate the behaviour of different types of bi-layer targets under multi-hit projectile impact. The JH-2 constitutive model has been used to reproduce the behaviour of alumina 99.5% and JC constitutive model has been used for steel 4340 and aluminium alloy 1100-H12. The total energy dissipation has been noted to be of lesser magnitude in case of sub-sequential impact in comparison to simultaneous impact of two projectiles. The distance between the impact points of two projectiles also effected the ballistic resistance of bi-layer target. The ballistic resistance of single tile ceramic front layer and four tile ceramic of equivalent area found to be dependent upon the boundary conditions provided to the target.

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.

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.

Numerical investigation on effect of different projectile nose shapes on ballistic impact of additively manufactured AlSi10Mg alloy

In the last few years, due to the superior mechanical qualities of Additive Manufacturing (AM) AlSi10Mg alloy to those of traditional casting process AlSi10Mg alloys, the application of AM technology has significantly increased. The ballistic impact research has a wide range of uses, notably in the mining, construction, spacecraft and defence sectors. This work focuses on analyzing the behavior of different projectile nose shapes on the AlSi10Mg alloy fabricated by AM. There are several projectile nose forms to consider, including blunt, hemispherical, conical, and ogive shapes. The impact of various projectile shapes on the ballistic limit of the additively created AlSi10Mg alloy is carefully examined in this study. All numerical simulations were carried out using LS-DYNA software, and the Johnson-Cook material and damage model were considered to assess the ballistic resistance behavior. The ballistic limit for various projectile shapes is computed using the Jonas-Lambert model, which describes the connection between residual velocity and starting projectile velocity. The results showed that, the ogive-shaped Projectile offers the highest ballistic limit, and the blunt projectile shows the lowest ballistic limit for a 5 mm thin target plate. The ballistic impact phenomenon showed plugging failure for the blunt nose projectile, the formation of plug and small fragments were observed in the case of hemispherical nose projectile, fragmenting failure is observed with radial necking in the case of conical nose projectile and petals are formed at the impacted zone in ogive nose shape projectile. Moreover, the ballistic limit of AM AlSi10Mg alloy was slightly higher compared to the ballistic limit of the die-cast AlSi10Mg alloy for the 7.62 mm AP bullet (core). Therefore, AM AlSi10Mg alloy may have equal or good ballistic properties compared to die-cast AlSi10Mg alloy.

Effects of Different Projectile Nose Shapes on the Impact Performance of the Aluminium 2024 Thin Plate

Effects of Different Projectile Nose Shapes on the Impact Performance of the Aluminium 2024 Thin Plate

Numerical Study on Aerodynamic Characteristics of Tail-stabilized Projectile with Asymmetrical Diversion Groove

A surface diversion groove with a specific geometry and position can influence the laminar flow characteristics of a projectile, which may affect the flight trajectory of an aircraft. The asymmetric flow field around the projectile can be induced by the diversion groove, which can produce an obvious aerodynamic force and moment at the projectile nose for trajectory correction. This study applied a diversion groove structure to the nose of tail-stabilized projectiles to investigate its impact on the aerodynamic characteristics of the projectile. The mathematical expressions for the aerodynamic force and aerodynamic coefficient were established theoretically. The change in the aerodynamic coefficient as a function of the phase angle of the diversion groove was determined. A parametric simulation was employed to investigate how the diversion groove affects the aerodynamic attributes of the projectile across various Mach numbers and angles of attack. The simulation results are consistent with the variation trends of aerodynamic forces and moments with respect to the phase angle of the diverter groove, as predicted by the static mathematical model. These findings demonstrate that the variation trends of the lift coefficient and pitching moment coefficient with respect to the angle β approximate a cosine function. Meanwhile, the variation trends of the yaw force coefficient and yaw moment coefficient with respect to the angle β approximate a sine function. The tail-stabilized projectile with asymmetrical diversion groove achieved a reduction of 1.2% in drag coefficient compared with that of the canard rudder corrective projectile, while the lift coefficient and pitch moment coefficient were increased by 6.4% and 16%, respectively, in the subsonic regime. The static margin of the projectile ranging from 13% to 16%. This study offers valuable insights for the design of corrective structures with diversion grooves and trajectory control.

Ballistic perforation of aramid laminates: Projectile nose shape sensitivity

The influence of projectile shape on the ballistic properties and mechanism of aramid laminates is investigated through experiments and simulations. Three types of projectiles (blunt, hemispherical, and ogival) are used to obtain ballistic curves. The dynamic penetration process, deformation and damage characteristics of the targets are analyzed. A three-dimensional finite element model is established, and good agreement is observed between the simulation and test results. The findings demonstrate that projectile shape significantly impacts the ballistic response of aramid laminates. As the projectile transitions from blunt and hemispherical to ogival, the ballistic limiting velocity decreases continuously, the area of target plate deformation and damage decreases, and the occurrence of delamination becomes less pronounced. And the energy dissipation through local damage, elastic deformation and overall motion of the aramid material is decreasing and the energy dissipation through friction is increasing.

Thermoelastic impact modeling for projectile–target–muzzle components during penetration start of motion

This paper presents the thermoelastic shock wave model components of projectile, target, and muzzle tube during the initial start of penetration. The penetration model is combined using pressure and temperature (e.g., mechanical and thermal shock) that act separately at the moment of penetration (a few microseconds) into a homogeneous or first-layer armor body. The armor’s shape and material will be investigated based on contact principal stress. The reciprocal influence between the penetrator and the armor in the aspect of the projectile nose shape will also be demonstrated. Moreover, the penetrator thermoelastic material’s durability will be examined, based on von Mises criterion. The examination for the initial elastic contact stress impact will be performed by using the explicit solution to temperature-displacement coupling equilibrium, based on commercial finite elements modeling. In addition, a modified impact contact stress model based on both mechanical and thermal energies was proposed and found to agree with the literature. Brief conceptual analysis of projectile–shield interactions was examined. Finally, shooting tube muzzle thermoelastic analysis was performed alongside a literature comparison, which was found to agree qualitatively and quantitatively. Muzzle tube material impact analysis was performed. Finally, it was concluded that muzzle tubes obey the rule that a shorter cylinder length tube develops higher muzzle tube principal stresses.

Photon Doppler velocimetry for resolving vertical penetration into sand targets

This paper presents details for using a photon Doppler velocimeter (PDV) to produce high fidelity velocity penetration data from vertical penetration into granular soil targets. The PDV theory used for collecting data is presented, along with details relevant to soil penetration testing. Experimental aspects related to specific equipment used, measurement configurations implemented, power losses, and probe alignment are presented in order to facilitate replication. The PDV equipment were mounted on a vertical gas gun and used to measure conical and blunt nose rod projectile velocities in penetration into loosely packed and densely packed soil targets. An in-depth discussion of data smoothing and filtering, data sampling and repeatability is presented. Penetration tests in several soil targets are used to reveal important phenomenology of penetration in granular media. The roles of soil target bulk density and pore saturation are investigated in terms of Poncelet drag and bearing resistance parameters. It is shown that bulk density plays a major role in penetration resistance while saturation has a secondary effect. The Poncelet drag coefficient was found to be projectile nose shape dependent. The drag coefficient was as high as 2.0 in penetration of blunt nose projectiles in densely packed sand, while a conical nose reduced the drag coefficient to 1.4. Saturation reduced the drag coefficient by 32 % and 28 % in densely packed and loosely packed soil targets, respectively.

A numerical ballistic performance investigation of Armox 500T steel through ductile damage models

In this work, the ballistic response of an armor steel, Armox 500T, is numerically investigated through finite element (FE) analysis by utilizing the Johnson–Cook (JC) and modified Mohr–Coulomb (MMC) damage models, with a focus on emphasizing the consequences of different modeling approaches. Although Lode-dependent failure models are considered to increase the accuracy of numerical predictions for ductile failure, there remains a complete lack of clarity as to whether all conditions and materials necessitate the adoption of such models for ballistic impact simulations. In this context, MMC and JC model parameters are calibrated through tensile test data available in the literature enabling direct comparison between them. Damage models are then validated using ballistic impact tests of Armox 500T performed with 7.62 API projectiles. The results indicate that the MMC model outperforms the JC model at predicting the failure modes while both models demonstrate strong performance in anticipating the residual velocity. The influence of projectile nose shape, target plate thickness, and impact angle are further investigated, and the effect of incorporating the Lode parameter is discussed in detail. Impact simulations with the blunt projectile nose shape is found to be highly sensitive to the effect of Lode angle on failure, with differences of up to 20% between models, while 7.62 API shows the lowest sensitivity. The difference between the models’ predictions is observed to increase at lower impact velocities and higher impact angles demonstrating the necessity of a Lode-dependent failure model for such cases. The JC model consistently yields smaller residual velocities compared to the MMC model in all cases indicating that the MMC is more conservative in terms of predicting protective performance of Armox 500T.

The DISCS method for perforation simulation of thin metallic plates by a rigid projectile

The DISCS method had been developed for penetration analysis of an axisymmetric projectile with a slender nose into a semi-infinite medium. Recently, the authors developed an approximate approach to assess perforation of concrete slabs of finite thickness, using the DISCS method. The present paper extends the approximate model to the perforation analysis of ductile metallic thin plates and determines the key parameters of the projectile residual velocity, the target perforation limit, and the ballistic limit. The present investigation focuses on thin metallic plates, the thickness of which is considerably smaller than that of the concrete slabs and smaller in comparison to the projectile nose length. The method is rather simple, easy to implement and provides a fast solution. An idealized target is characterized by a set of discs of small thickness responding in the plate plane, disregarding the local damage around the penetration ductile hole. The in-plane response of the discs during penetration and perforation of an idealized target are calculated. The Residual Velocity upon perforation of the Idealized Target (RVIT) is lower than the residual velocity of the real plate since it disregards the local damage, hence, the RVIT is the lower bound of the true residual velocity of the real perforated thin plate. Therefore, a positive RVIT for the thin plate with a given thickness indicates right away that the real target will be perforated. Using the RVIT parameter, the proposed DISCS method turns into a series of RVIT-perforation problems of plates with thicknesses that are smaller than the real thickness, to determine the decreasing RVIT with increasing thickness, until the full thickness is considered. The analysis is carried out using the modified (hybrid) DISCS method, that aims at analyzing penetration depth into a thick target. The analysis is based on the theoretical field equations and the constitutive equations of the plate material. The proposed method is based on a theoretical model and on engineering insight. Neither empirical constants nor any calibrations are required. Validation of the proposed method is carried out thorough comparisons with numerous test data on ductile aluminum and steel plates of different thicknesses that are struck by rigid projectiles at different impact velocities. All the comparisons demonstrate very good correspondence between the proposed method predictions and the test data.

Experimental study on ballistic stability of truncated cone projectile in high-speed oblique water entry

In this paper, the high-speed photography technique was used to study the high-speed oblique water entry of truncated cone projectiles, and the effects of nose shape, projectile velocity and entry angle on the cavity and ballistic characteristics of oblique water entry were discussed. The experimental results show that the influence of nose shape on the oblique water entry cavity and ballistic characteristics is related to the nose wetted area. For the same type of projectile, with the increase of projectile velocity, the cavity size becomes larger at the same penetration displacement and the surface closure time gets longer. Moreover, with the increase of entry angle, the surface closure time decreases, the velocity attenuation gets faster, at the same penetration displacement the cavity opening length becomes shorter and the cavity asymmetry weakens. Additionally, the results indicate that the trajectory stability of the truncated cone projectile varies under different water entry velocities and attitude angles.

A Numerical Study on Projectile Penetration into Underwater Torpedo Warhead

Underwater torpedo interception could be conducted by shell perforation or even warhead impact detonation with high speed projectiles. This work deals with the projectile water entry and sequent penetration into underwater torpedo whereby both aluminium shell perforation and explosive detonation are numerically studied. The water entry model and aluminum impact model are validated against test data for underwater aluminum shell penetration. Targets are located under water with 20 cm depth where aluminium shells for penetration are air-back while the impact detonation model has explosives inside shell. Four kinds of different nose shape tungsten projectiles are used for penetration simulation, revealing that ogival nose projectiles have superior performance for both shell perforation as well as detonation than conical nose projectiles. Numerical predictions shed some light on nose shape optimization design of high velocity projectile against torpedoes.

Effect of Lode angle and projectile diameter on the ballistic resistance of 6061-T651 aluminum alloy plates struck by hemispherical nosed projectile

Aluminum alloy has been gradually applied to the field of armor protection because of its excellent material properties. The research on its ballistic resistance has important theoretical and engineering application value. In order to study the ballistic resistance of 6061-T651 aluminum alloy plate, the impact tests of 6061-T651 aluminum alloy plate against hemispherical nosed projectile with a diameter of 12.66 mm were carried out with a light gas gun system and the ballistic limit velocity and failure mode of the target plate were obtained. Subsequently, the numerical simulations corresponding to the tests were carried out by using the Lode dependent and independent fracture criteria, and the effect mechanism of the Lode angle on the numerical simulation results were analyzed. Finally, the effect of projectile diameter on the ballistic resistance of the target plate was analyzed by the expansion of numerical simulation. The research results show that the numerical simulation will be quite different from the test results if the effect of the Lode angle on the material fracture strain is not considered. As the diameter of the projectile increases, the armor-piercing efficiency of the hemispherical nosed projectile is improved since the energy dissipation mechanism of the target plate gradually changes from ductile hole enlargement to shear plugging.

Study on Mass Erosion and Surface Temperature during High-Speed Penetration of Concrete by Projectile Considering Heat Conduction and Thermal Softening.

The mass erosion of the kinetic energy of projectiles penetrating concrete targets at high speed is an important reason for the reduction in penetration efficiency. The heat generation and heat conduction in the projectile are important parts of the theoretical calculation of mass loss. In this paper, theoretical models are established to calculate the mass erosion and heat conduction of projectile noses, including models of cutting, melting, the heat conduction of flash temperature, and the conversion of plastic work into heat. The friction cutting model is modified considering the heat softening of metal, and a model of non-adiabatic processes for the nose was established based on the heat conduction theory to calculate the surface temperature. The coupling numerical calculation of the erosion and heat conduction of the projectile nose shows that melting erosion is the main factor of mass loss at high-speed penetration, and the mass erosion ratio of melting and cutting is related to the initial velocity. Critical velocity without melting erosion and a constant ratio of melting and cutting erosion exists, and the critical velocities are closely related to the melting temperature. In the process of penetration, the thickness of the heat affected zone (HAZ) gradually increases, and the entire heat conduction zone (EHZ) is about 5~6 times the thickness of the HAZ.