Hemispherical Projectile Research Articles

Influence of projectile shape on ballistic behavior of 3D shallow straight-joint woven fabrics

This study investigates the influence of projectile shape on the ballistic behavior of 3D shallow straight-joint woven fabrics (3DSSWFs). Utilizing a series of numerical simulations, we analyze the impact resistance and energy absorption capabilities of 3DSSWFs when subjected to projectiles of varying geometries. The projectile setup includes spherical, conical, flat, and hemispherical projectiles to comprehensively assess their effects on fabric deformation, damage mechanisms, and overall ballistic performance. Results indicate that projectile shape significantly affects the penetration resistance and failure modes of 3DSSWFs. Spherical projectiles tend to cause extensive delamination and localized fabric failure, whereas conical and flat projectiles exhibit different interaction dynamics, influencing the energy dissipation patterns within the fabric matrix. The findings of this study provide critical insights into the complex relationships between projectile geometry and fabric response in 3DSSWFs. By elucidating the role of projectile shape in determining the ballistic limit, energy absorption capacity, and failure mechanisms, this research contributes to the broader understanding of impact dynamics in advanced textile structures.

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.

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.

Low velocity impact and compression-after-impact response of hybrid pseudo-woven meso-architectured carbon/epoxy composite laminates manufactured via automated fiber placement

An experimental study is presented on the low velocity impact (LVI) and compression after impact (CAI) response of T800-SC carbon/epoxy laminates manufactured via automated fiber (AFP) placement manufacturing. Two hybrid laminate configurations consisting of unidirectional and pseudo-woven meso-architectured composite (MAC) sub-laminates are compared against a traditional quasi-isotropic control laminate. MAC sub-laminates are manufactured via a modified AFP process implementing tow skips. The MAC architecture is macroscopically heterogeneous with discontinuous and spatially varying fiber orientations both in-plane and through thickness resulting in multiple interfaces and an expanded design space. The laminates are tested under LVI energies of 15–55 J using a 25.4 mm diameter hemispherical projectile according to ASTM D7136. The results show similar load-displacement responses but significant difference in the LVI damage profiles and CAI strengths for the different configurations. The hybrid laminate configurations exhibit increased damage resistance with up to 37% higher critical delamination load and increased damage tolerance with 26% higher residual compressive strength after an impact of 55 J compared to control laminate.

Numerical Study of Unstable Shock-Induced Combustion with Different Chemical Kinetics and Investigation of the Instability Using Modal Decomposition Technique

An unstable shock-induced combustion (SIC) case around a hemispherical projectile has been numerically studied which experimentally produced a regular oscillation. Comparison of detailed H2/O2 reaction mechanisms is made for the numerical simulation of SIC with higher-order numerical schemes intended for the use of the code for the hypersonic propulsion and supersonic combustion applications. The simulations show that specific reaction mechanisms are grid-sensitive and produce spurious reactions in the high-temperature region, which trigger artificial instability in the oscillating flow field. The simulations also show that specific reaction mechanisms develop such spurious oscillations only at very fine grid resolutions. The instability mechanism is investigated using the dynamic mode decomposition (DMD) technique and the spatial structure of the decomposed modes are further analyzed. It is found that the instability triggered by the high-temperature reactions strengthens the reflecting compression wave and pushes the shock wave further and disrupts the regularly oscillating mechanism. The spatial coherent structure from the DMD analysis shows the effect of this instability in different regions in the regularly oscillating flow field.

The false nose shape in a high velocity projectile penetration into dry sand

The present article deals with a particularly interesting phenomenon of a false nose that is formed during the high velocity penetration of a projectile into a granular soil like sand. The false nose is composed of compacted, fractured, and comminuted sand particles. It is formed as a cap in front of flat nose projectile and accompanies the projectile during its penetration. Only limited sparse experimental evidence exists on the false nose shape that is mostly observed after the penetration event. So far, no theoretical study was carried out to assess the false nose shape and its effect on penetration. The present paper conjectures that the shape of the false nose is equal to the optimal shape formed from the target soil material that yields the minimal resistance during its penetration in the soil. This nose together with the original flat nose projectile behind, yield a stable deep penetration that is comparable to projectiles with shaped noses. The present study extends the approach of a full false nose in front of a flat nose projectile, to a partially added false nose in front of a hemispherical, spherical, or other short noses. Analysis of experimental images of false noses verifies the above conjecture and prove that the shape of the false nose is very close to the optimal shape of a projectile nose that is made of compacted soil. These findings enable implementation of the well-proven DISCS approach (which was originally developed for penetration of projectiles with slender noses into various compressible media) and extend it for flat, spherical and hemispherical projectiles penetration into a granular soil. The efficiency of the proposed approach is demonstrated through numerous examples for the above types of projectiles, at various impact velocities, showing very good agreement with experimental data.

A comparative study on the ballistic performance of aramid and aluminum honeycomb sandwich structures

This study investigated the perforation phenomenon of aramid and aluminium honeycomb sandwich structures under high-velocity impacts and compared the impact responses experimentally and numerically. The dimension of the face sheets used was 1 mm in thickness and 220 mm in diameter, and for both the honeycomb cores, the cell thickness of 0.05 mm and the cell size of 3.2 mm was used. Ballistic impact tests were conducted by employing a pneumatic air gun to study damage behavior and failure modes under different impact velocities between 35 m/s and 150 m/s using conical shaped and hemispherical shaped projectiles.Three-dimensional finite element models were implemented in ABAQUS/Explicit to model sandwich panels.The numerical model was validated with experimental data and, subsequently, the numerical study was further extended to study the effects of different geometrical parameters affecting the impact response of sandwich structures. The results showed that for the ballistic limit, sandwich structure having an aluminium honeycomb core performed better than the aramid honeycomb core by 3.09% and 2.5% against conical and hemispherical projectiles, respectively. However, the aramid honeycomb structure was proven to be more efficient than the aluminum honeycomb structure in terms of energy absorption and specific energy absorption.

High velocity impact response of corrugated core composite sandwich structures

The mechanisms of projectile penetration of composite sandwich panel with empty, trapezoidal corrugated cores have been experimentally investigated. The panels have been designed to investigate the influences of specific parameters, like the fiber type of corrugated core, the projectile nose shape and the stacking sequence of face-sheets, on the impact performance from the aspects of sequential deformation, failure modes and associated mechanisms. Experimental results demonstrated that usage of Twill glass fiber in corrugated core is attained highest performance in term of energy absorption and residual velocity for the fully perforated specimens. Comparisons of panels with different stacking sequences for face-sheets verify that the corrugated core composite sandwich structures with [Formula: see text] stacking sequence is indicated the highest energy absorption. This panel is displayed a superior resistance over the ones with other stacking sequences. The hemispherical projectile is showed no deviation from the direct line of path flight relative to the conical and blunt projectile in the high velocity impact test. Moreover, the deviation of the projectile decreases the damage area in specimens.

Effects of textile structure and projectile geometry on ballistic performance of UHMWPE textiles

The ballistic performances of three ultrahigh molecular weight polyethylene (UHMWPE) textile structures (2D braided, 2D triaxial braided and 3D orthogonal woven) are studied. The tensile strength of UHMWPE yarn is first measured by quasi-static tensile experiment. By inputting the measured material parameters, numerical models including macro-meso model and mesoscopic models are established and these numerical models are validated by a ballistic experiment of 2D braided textile. The ballistic performances of three textile structures under impact of three different head-shape projectiles (flat, sharp and hemispherical nose) are investigated, using the macro-meso model. Based on the analysis of ballistic limit, failure mode and energy dissipation, we demonstrate that the 2D triaxial braided (2D3A) textile has better ballistic performance than the 2D textile. All three textile structures show the least ballistic damage by flat projectile, followed by sharp and hemispherical projectile.

The experimental and numerical analysis of the ballistic performance of elastomer matrix Kevlar composites

In this paper, the behavior of high-velocity impact of Kevlar fabric and elastomer composites was investigated both experimentally and numerically. The experimental tests were performed by a gas gun device and hemispherical projectiles at different velocities, ranging from 122 m/s to 152 m/s for 2- and 4-layer samples. The penetration resistance of these composites during impact was determined using ABAQUS/Explicit. The present study's novelty lies in choosing the finite element model for Kevlar fabric and elastomer matrix in composites with nonlinear behavior to estimate the damage mechanism in the impact zone. For this purpose, the material model of the formable was used to define the damage criteria for Kevlar, and the material model of the VUMAT was used to consider the non-linear behavior and damage evolution of elastomer matrix with one of the damage criteria. Then, the dynamic behavior of the laminate was studied by a Split Hopkinson Pressure Bar. The effect of the number of layers, the shape of the projectile, the energy absorption and failure mechanisms were studied. The verification of this numerical model with experimental observations showed good agreement. The results reveal that elastomeric composites can cause to increase energy absorption and reduce the damaged area.

FEM Simulation of High Speed Impact Behaviour of Additively Manufactured AlSi10Mg Alloy

The present work investigates impact behaviour of additively manufactured AlSi10Mg alloy and ballistic limit of projectiles using FEM simulations. Tensile tests, dynamic tests and elevated temperature tensile tests simulations were performed on smooth and notched specimens to calculate Johnson–Cook material and damage model parameters, which are subsequenty given as inputs for impact simulation. The relationship between residual velocity versus initial projectile velocity is expressed using Jonas–Lambert’s model for calculating ballistic limit. The effects of projectile velocity, its shape, thickness and material property of AlSi10Mg on ballistic limit were thoroughly investigated. C3D8R elements are used to discretize the target plate and mesh transition zone was created in impact region. Johnson–Cook elasto-viscoplastic model was employed to study the ballistic resistance behaviour of AlSi10Mg alloy. Fracture energy value of 43.6 kN/m for AlSi10Mg alloy is used to initiate the damage in target plate. All FE simulations were performed by using ABAQUS/Explicit. It is observed that ballistic impact on 3D printed AlSi10Mg has shown plugging and petaling failure when hemispherical projectile was used while plugging failure in the case of blunt projectiles. The ballistic limit of hemispherical projectiles is found to be higher (311 m/s, 400 m/s) compared to the blunt projectiles (216.5 m/s, 245 m/s). The impact velocity to completely penerate 6 mm thick target plate is relatively higher as compared to 3 mm thick target plate for both projectiles.

Influence of metal/composite interface on the damage behavior and energy absorption mechanisms of FMLs against projectile impact

This paper focuses on the interface failure in metal/GFRP laminates on account of the high-velocity impact phenomenon by a hemispherical projectile. The study considers three laminates in which the failure inside the 8-layer 0/90 GFRP laminate is compared with the other two laminates that include metal layers in their layup configuration. The metal layers were placed on the top and bottom on one type of laminates while in the other additional metal layers are placed symmetrically inside the layup as well. They were subjected to high-velocity impact by a hemispherical projectile at different energy levels and the idea is not to perforate the laminate configuration instead to account for the damage incurred in these laminates and the role of metal layers in providing resistance to damage within these laminates. The study utilizes experimental findings and proposes a rate-dependent Finite Element (FE) model consisting of the Hashin-Puck failure scheme for composite and the Johnson-Cook damage model for metal layers. The results of the model satisfactorily agree with their experimental counterparts and provide valuable insight into the damage resistance inside the laminates. It has been observed that the 8-layer GFRP laminate was good in terms of elastic recovery and prevention of propagation of damage inside the laminates only, till the impact energy was lower. For higher impact energy, they show poor damage resistance as the fiber failure is triggered in them. However, laminates with metal layers are shown to protect the laminate by dissipating energy in the delamination of metal/GFRP interface, shear failure of the metal layer, and on account of metal plasticity. The study further shows that the through-thickness compressive stresses were responsible for the failure of laminates and also triggering the delamination in them. A damage energy study was performed to investigate the amount of energy dissipating in various failure modes like delamination, matrix cracking, fiber failure, etc.

Numerical Study on Ballistic Resistance of Thin Aluminium Plate Subjected to Variable Diameter Projectile Impacts

The ballistic resistance of a thin aluminium plate was investigated against rigid hemispherical nosed projectile impact. The target span was varied as 68 mm, 100 mm, 150 mm and impacted normally by 19 mm diameter hemispherical nosed projectile. The residual velocity and ballistic limit velocity obtained from the numerical results using nonlinear finite element code LS-DYNA is compared with the experimental results available in the literature. Further, parametric study has been carried out for different projectile diameter with the same target span and validated with Recht and Ipson’s model. The ballistic limit has been decreasing with decrease in projectile diameter and it is also observed that ballistic limit of the target increases with increase in target span diameter.

Experimental and numerical investigation of the impact response of elastomer layered fiber metal laminates (EFMLs)

The aim of the present study is to investigate the effect of introducing an elastomer layer into conventional fiber metal laminates on their perforation resistance. Natural compounded rubber as elastomeric media and glass/epoxy composite were sandwiched in between two layers of aluminum 6061-T6 and then the resulted structure was perforated by a 10 mm diameter hemispherical projectile at different impact velocities. Residual velocities were recorded by a high speed camera via a shadowing technique. Results showed that an elastomer layer located nearer to frontal face had a better energy absorbing performance due to load spreading; besides, by increasing the impact velocity the elastomer performs more efficiently because of the elastomer damage initiation point movement toward the periphery of the stretched area. Numerical simulation of penetration process was accomplished using the advanced finite element code of LS-DYNA. Finally, a numerical parametric study was performed to assess the effect of elastomer thickness on the energy absorption efficiency (EAE) of the whole structure. Based on the obtained results, adding an elastomeric layer into the structure is more beneficial than composite thickening at the same thickness in terms of improving EAE and reducing areal density.

Numerical and Experimental Investigation of Supercavitating Flow Development Over Different Nose Shape Projectiles

Recently, the interest for new technologies to speed up underwater vehicles has increased. In this work, one of these technologies is investigated by creating a gaseous cavity, in which the high-speed underwater vehicles flow, to reduce the drag forces acting on these vehicles. A supercavitating flow over different nose projectile shapes is studied numerically and experimentally to understand the effect of the projectile nose shape on the supercavitating flow behavior. The numerical simulations are accomplished by using a commercial code named ESI-CFD through an unstructured mesh. Also, supercavity flow characteristics are investigated experimentally over the projectile body by using a high-speed camera. The numerical results are validated with other experimental results, where the stages of growth of the cavity over the different shapes projectiles are distinguished briefly and the existence of wake vortex is observed. The cavitator shape controls the time of cavity appearance and the drag coefficient value. The hemispherical nose projectile has the lowest drag coefficient value among all the tested projectiles. So, the cavitating flow behavior is investigated for the hemispherical nose projectile at different cavitation numbers ranging from 0.065 to 1.0. A new correlation is deduced to investigate the drag coefficient for the hemispherical projectile. Good agreement is obtained from the result of this correlation and previous data. Also, a new cavitator shape (a modified conical cavitator projectile) is examined, which is a modification of previously used one. The supercavity has not been formed using the modified conical cavitator projectile but it moves faster than any other examined projectile because it takes longer time before the cavity begins to decay.

Dynamic perforation of ultra-hard high-strength armor steel: Impact experiments and modeling

The dynamic perforation of 3 mm thick target plates extracted from ultra-high strength steel (Mars® 300) is investigated experimentally and computationally. Projectiles of 8 mm diameter are also extracted from Mars® 300 plates featuring blunt, conical and hemispherical tips. Using a single stage gas gun, impact experiments are performed with projectile velocities of up to 380 m/s. A minimum impact velocity of about 240 m/s (ballistic limit) was required to perforate the armor steel targets with conical and hemispherical projectiles of a mass of about 14 g. In all successful perforation experiments, the plate targets failed through plugging. At the same time, the conical and blunt projectiles are heavily deformed in a way that their final tip shape resembles that of the hemispherical projectiles. The latter turned out to be slightly more efficient than conical ones in the sense that their exit velocities are approximately 10% higher. Numerical simulations are performed of all impact experiments using the finite element software LS-DYNA. The plasticity model made use of a quadratic yield function with non-associated flow rule, a Swift-Voce strain hardening law and Johnson–Cook type of multipliers accounting for the effects of strain rate and temperature. The stress-triaxiality, Lode angle parameter and strain-rate dependent Hosford-Coulomb fracture initiation model is employed to predict the ductile failure of the Mars 300 steel. Overall, the simulation results are in good agreement with the experimental observations, including the mode of perforation (shear plugging) and the projectile exit velocities. The numerical simulations also show that a ring-like band of localized plastic deformation forms inside the targets with temperatures of up to 700 °C. Fracture initiates from the back face of the plate under biaxial tension, while the cracks propagate through the band of localized plastic deformation towards the impacted front face of the plate, thereby forming a plug as the projectile passes through the target.

Impact properties of kenaf Fibre/X-ray films hybrid composites for structural applications

Most existing designs of high velocity impact resistant materials are either heavy or expensive, so in markets the demand for lighter and cheaper materials is always on the rise. The aim of this work to investigates the effect of different projectile shape and impact velocities on the energy absorption and compression after impact of kenaf/X-ray/epoxy hybrid composites. Kenaf fibre treated with NaOH solution and perforated X-ray films were chosen as a reinforcement in the epoxy matrix to fabricate hybrid composites. The hybrid composites were fabricated using conventional hand lay-up method followed by compression moulding and were subjected to high velocity impact tests using a single stage gas gun. The pressure settings of the gas gun were varied as follows: 20bar, 30bar, 40bar and 50bar, while the projectiles used were of three types: blunt, hemispherical and conical ones. After the high velocity impact tests, the composites underwent dye penetration inspection and were subjected to compression after impact tests. The obtained results revealed that the hybrid composites subjected to high velocity impact with hemispherical projectile exhibited the highest energy absorption, compared to the conical and blunt geometry. On the other hand, the hybrid composites subjected to hemispherical projectile impact possess the lowest residual strength compared to conical and blunt geometry. The dye penetration test as well as the visual inspection also revealed that the hemispherical projectile produces the biggest damage compared to the other two projectile types. We concluded that developed kenaf/X-ray/epoxy hybrid composites suitable for ballistic applications.

High velocity impact behavior of Kevlar/rubber and Kevlar/epoxy composites: A comparative study

This paper presents a comparison of behavior and energy absorption of neat Kevlar fabric and polymer matrix composites under high velocity impact loading. Two types of matrices including rubber and thermoset (epoxy) matrices were used in order to study the effect of a hard and brittle matrix compared with the soft and flexible matrix on energy absorption of the composite. Moreover, two types of rubber matrix with high hardness (HH) and low hardness (LH) were used in this study to investigate the effect of rubber matrix formulation on impact resistance of composites. Ballistic impact tests were performed by firing a 10 mm hemispherical projectile onto neat fabric and composites in a velocity range of 30–150 m/s for two- and four-layer samples. Results show that the matrix affects the ballistic performance of composites significantly. Rubber matrix enhances the energy absorption of the fabric by keeping composite flexibility. Increase the number of layers for Kevlar/rubber composite results in better ballistic performance. On the contrary, the thermoset matrix leads to an inflexible composite that restricts the fabric deformation and has a negative effect on the fabric’s ballistic performance. Finally, damage mechanisms were discussed in detail for each sample.

Numerical and experimental study of impact on hyperelastic rubber panels

This study presents the response of rubber panels subjected to high-velocity impact loading. The mechanical properties and impact performance of rubber panels are altered by the variation in compound ingredients. To investigate the effect of compound ingredients, two types of rubber panels with high (SHA70) and low hardnesses (SHA45) were prepared, and mechanical properties and impact resistance of the panels were measured by high-velocity impact tests in a velocity range of 70–160 m/s. Ballistic limits of about 80 and 94 m/s were obtained for the low- and high-hardness rubbers, respectively, which show that the energy absorption of rubber panels increases as filler loading content increases. In this respect, the finite-element simulation has been performed to investigate the ballistic performance of rubber panels numerically. Rubber panel has been modeled using the LS-DYNA software and employing the experimental results of tensile test to characterize the behavior of panel. The findings show a good agreement between the numerical and experimental data. To study the effect of projectile’s shape, impact resistance of the rubber panels against hemispherical projectiles with different length-to-diameter (L/D) ratios (projectiles with diameters of 8, 10, and 12 mm) was measured and the model was also used. The results demonstrate that energy absorption of the panel increases as the diameter of projectile increases. The energy absorbed by the rubber panels appears in the form of damages that lead to increase their damage zone.

Penetration of Hemispherical Projectile Into the Three Layer Targets with Different Materials and Layouts

In this paper, the penetration of a hemispherical projectile into the targets with three adjacent layers (without air gap) with different arrangement and materials has been studied. To study the set parameters, some ballistic tests as well as FEM simulations had done and the numerical results compared with experimental ones. While defining ballistic limit for the projectile-target system, the effect of layers arrangement sequence and material in their ballistic operation was perused. The result of the experiments showed that if the aluminum plates (harder material) are placed in the two first layers and CU (softer material) is placed in the third layer, the resistance against penetration will have the maximum value. Experimental results show that by decreasing the initial velocity of projectiles, velocity downfall is increased while the amounts of absorbed energy do not change significantly. The projectile velocity has a significant effect on the fracture mode. Increasing the velocity make the fracture accomplish in the Plugging mode while decreasing the velocity get the fracture to take petaline mode.