Steel Projectiles Research Articles

Study on the attenuation pattern of stress wave in granite impacted by 30CrMnSiA alloy steel projectiles at 1.5–5.5 km/s

The damage ability of hypervelocity kinetic energy projectile penetrating ground has become a hotspot in modern military research. In this study, a hypervelocity impact test on a granite target subjected to projectiles using a two-stage light gas gun is conducted to study the stress wave evolution in granite under hypervelocity penetrations. The parameters of the *MAT_JOHNSON_HOLMQUIST_CERAMICS(JH-2) constitutive equation are calibrated using the results of the splinter impact test and the static test, and numerical simulations are performed using the smoothed particle hydrodynamics method coupled with finite element method (SPH-FEM coupled method) to extend the resulting data. A formula for calculating the stress wave peak attenuation is established, indicating that the maximum impact pressure produced by the hypervelocity impact decreases exponentially with scaling distance, and the attenuation coefficient is related to the degree of rock damage. Additionally, the attenuation of the speed of sound is used to characterize rock damage, and the damage deterioration law of granite under hypervelocity impact is analyzed based on the damage factor.

Local structural behaviour of the outer containment of an NPP against hard missile impact

An aircraft crash and missile impact on a nuclear containment structure is currently described as an event beyond design basis; however, soon, it will be qualified as a primary design criterion. In the present study, the structural and dynamic behaviour of the outer containment of a nuclear power plant (NPP) has been studied to substantiate its structural integrity against the rigid missile impact. Scaled experiments (at a 1:4 and 1:3 ratio with respect to shell thickness) have been performed to study the localized behaviour of the containment structure against 10 and 20-kg rigid steel projectiles. The reinforced cement concrete (RCC) targets of thicknesses 150 and 200 mm have been subjected to impact at incidence velocity close to the landing and taking of velocity of the aircraft. The flexural reinforcement ratio was considered 1.25 % for a 150 mm thick target and 1.53 % for a 200 mm thick target. The effect of shear reinforcement on the penetration and perforation resistance has been studied for a 200 mm thick RCC target. A detailed post-test examination was conducted to evaluate the localized physical damage characteristics such as spalling and scabbing of concrete, penetration, perforation, crack propagation, and the damage induced in both flexural and shear reinforcements. The mechanics of deformation and failure modes of the target were investigated under varying incidence velocities, 60–115 m/s. The reinforcement characteristics under dynamic loading, such as strain time histories, strain rate sensitivity, and dynamic material properties, were also investigated. The presence of transverse reinforcement in 200 mm thick targets improved the ballistic performance by 12.50 %. Furthermore, the transverse reinforcement also played a crucial role in restricting the bending of the rear face flexural reinforcement and controlling the rear face damage propagation.

Dynamic response of UHMWPE/polyurea composite plates under combined blast and ballistic impact

Combined load caused by blast impulse and fragmentation impact poses a synergetic damage threat to the protective structure. To improve the blast and ballistic impact resistance of Ultra-high molecular weight polyethylene (UHMWPE), polyurea coated Ultra-high molecular weight polyethylene structure was proposed, and the composite structures with different coating thickness and coating position were prepared. Composite projectiles formed by combining foam projectiles and steel projectiles were launched by light gas gun to simulate the combined load of explosion impact and fragmentation. Comparative experimental studies were carried out. The experimental results show that the polyurea layer has good elastic properties, preventing the excessive deformation of the PE layer. The polyurea coating position and the time interval of the combined load show significant influence on the impact resistance of the composite structure. When the load was relatively low, PE plate with polyurea coating on booth face has both the advantages of PE plate with coating on the front and back face, but when the load increased, the impact resistance potential of polyurea layer was not fully developed. With the increase of the combined load, structures with polyurea coating on the back face has a good resistance of combined impact.

Quantitative Characterization of the Perforation Behaviour of Direct Recycled Aluminum Alloy 6061 Plates Subjected to High-Velocity Impact

This study aims to establish the perforation behaviour of direct recycled AA6061 to help establish the properties of the current most optimized direct recycled AA6061 through the hot press forging technique. This was achieved by subjecting direct recycled AA6061 plates of varying thickness to high-velocity impacts using a single-stage gas gun setup. The impactor is a hemispherical steel projectile of 13mm in length and 8.5mm in diameter. Plates of 3,4,5 and 10mm thickness were tested at velocities ranging from 120 m/s to 402 m/s. The deformation profiles of the impacted plates were captured and analyzed to quantitatively establish the perforation behaviour of recycled AA6061 plates. The plates showed irregular and non-axis symmetric patterns of deformation hinting the material exhibits anisotropic properties. The changes in the deformation profile were investigated in relation to changes in impact velocities and plate thickness were made to understand how they impact the profile. The deformation area was observed to be decreasing when the bullet impact velocity was increased. Higher velocity impact events lead to more material ejection from the plate in the form of fragmentation. Additionally, the deformation zone was observed to be getting smaller with an increase in the thickness of the plate. Thicker plates were found to have more fragmentation compared to thinner plates. Ductile failure characteristics such as petal formation and plugging were observed along with brittle characteristics such as fragmentation and conal fractures. Lower-velocity impacts lead to more energy absorbed by the target plates. Thicker plates observed more of the bullet’s energy. Through experimentation, the deformation behaviour of the directly recycled AA6061 material was established. This data can be used as a base for further research into the material’s behaviour characterisation.

The investigation of deflection behavior in carbon/epoxy and glass/epoxy composite laminates under low-velocity impact with small projectiles

This study examined the impact behavior of carbon/epoxy and glass/epoxy composite laminates with 2, 4, and 6 mm thicknesses under low-velocity tests. The investigation involved subjecting the composite laminates under small-impact loads using spherical, cylindrical, and conical steel projectiles, each weighing 3 g. The impacts conducted at 29.5, 36.5, and 51 m/s velocities. This investigation modeled using finite element (FE) methods and analytical approaches. In the analytical method, the mass and spring model used for the impact of small projectiles. The research findings revealed that, in 2 mm thick carbon/epoxy composite laminates, the maximum deflection at the mid-point induced by a spherical projectile was 1.37 mm. This value exhibited a 48.91% and 19.13% increase compared to impacts with cylindrical and conical projectiles, respectively. Additionally, a comprehensive examination of delamination across all samples indicated the maximum delamination occurrence in glass/epoxy samples, showcasing lower impact resistance than carbon/epoxy laminates. Notably, with an increase in thickness, the delamination phenomenon in the samples exhibited a decreasing trend. In addition, the maximum value of delamination in the composite laminates were with spherical, conical, and cylindrical projectiles respectively, and also, there was an excellent convergence between FE and analytical results.

Mechanical behavior of STF impregnation and anti-impact performances of Kevlar and UHMPWEF fabric impregnations

STF-impregnated Kevlar and ultra-high molecular weight polyethylene (UHMWPEF) fabric-impregnated bodies were prepared by using mass fraction of 34 % SiO2 with a particle size of 100 nm and PEG400 as dispersion and dispersant, respectively. When two kinds of fiber fabrics were impregnated by STF, the tensile, single fiber pull-out and single fiber tensile loads of Kevlar fabric-impregnated increased 26.63 %, 155.55 %, and 98.64 %, respectively. However, the tensile load, monofilament pull-out load and monofilament tensile load of the UHMWPEF fabric-impregnated body increased 100.14 %, 729.03 % and 51.61 %, respectively. Kevlar fiber fabric impregnated by ultrasonic vibration and smearing STF absorbs more steel projectile’s kinetic energies of 52.3 % and 27.43 % than that of the original fiber fabric, respectively. UHMPWEF fabric impregnated by using ultrasonic vibration and smearing increased 65.56 % and 47.73 % than the original fabric absorbing steel projectile’s kinetic energy. Based on the Scanning Electron Microscope (SEM) observation of the fiber fabric surface, it was found that the connection between the fibers was significantly strengthened after the STF impregnation treatment. When the fabric was subjected to impact load, STF played an important role in transmitting load and increasing friction.

Evaluating the performance of ceramic/fabric composite panels against simultaneous steel projectile impacts: An experimental and numerical study

In order to evaluate the ballistic performance of ceramic/fabric composite panels developed using 99.5 % alumina, Kevlar® and carbon fiber fabrics; a series of experiments were performed on the physical samples. The composite-projectile interaction was investigated in detail by means of finite element analysis using LS-DYNA®. The validated numerical model of the ceramic/fabric composite system was tactically modified to investigate the composite/projectile interaction for simultaneous projectile impacts at different impact velocities. The numerical model predicted the failure mechanism of the composite panel and the exit velocity of the projectile piercing through the composite accurately. This study reveals the important aspects of ballistic impact on composites under simultaneous multiple projectile impact condition which in turn, is a much more complex and critical case as compared to sequential multiple projectile impacts.

Study on Dynamic Mechanical Properties of Sandwich Beam with Stepwise Gradient Polymethacrylimide (PMI) Foam Core under Low-Velocity Impact.

Different PMI foam materials of 52, 110, and 200 kg/m3 were used to design stepwise gradient cores to improve the impact resistance of the sandwich beam. The stepwise gradient core consists of three layers arranged in positive gradient, negative gradient, and sandwich-core (e.g., 200/52/200). These sandwich beams were subjected to the impact of a steel projectile under impact momentum of 10 to 20 kg·m/s, corresponding to impact energy in the range of 12.5 to 50 J. During the test, the impact force was recorded by an accelerometer, and the different failure modes were also obtained. Subsequently, the influence of the layer arrangement on the energy absorption and load transfer mechanism between the different layers was analyzed. The results showed that the top layer with a large density can improve the impact force, but the middle/bottom layer with a low density promoted specific energy absorption. Thus, based on these two points, the negative gradient core (200/110/52) had an excellent specific energy absorption because it can transfer and expand the area to bear the load layer by layer, which improved the energy absorption in each layer. Combined with the failure modes, the load transfer and deformation mechanisms between the layers were also discussed. The present work provided a valuable method to design an efficient lightweight sandwich structure in the protection field.

Wounding potential of muzzle-loaded projectiles discharged from unmodified blank pistols

ABSTRACT Blank pistols are considered non-lethal-purpose imitation firearms that have been modified to function as real weapons in many countries. In Taiwan, gang members use unmodified blank pistols to fire muzzle-loaded projectiles. Herein, the muzzle energy density (ED) of the discharged muzzle-loaded projectiles was used to evaluate the wounding potential of unmodified blank pistols. A series of firing tests was conducted using three unmodified blank pistols, two projectiles, and three brands of blank cartridges. The EDs of the projectiles were determined using ballistic chronographs. The means of the ED ( ED ‾ ) of the pistols firing various cartridges and projectiles were 20.3–48.6 J/cm2. These values are all substantially higher than the human skin penetration threshold value (10 J/cm2). The results indicate that unmodified blank pistols can fire projectiles and inflict severe injuries. Therefore, they should be legally controlled in Taiwan. Additionally, a Student’s t-test of ED ‾ between paired projectiles demonstrated a significant influence of the sectional density (m p /S) of the projectiles on their ED ‾ , which was attributed to the inversely proportional effects of m p /S on the downrange deceleration of the projectiles. The results of this study indicate that steel projectiles are suitable for evaluating the wounding potential of unmodified blank pistols.

High velocity steel spheres impact and damage analysis of graphene doped T700 composite shielding panels

Composite materials are increasingly being used in aircraft components such as fuselage panels which are subject to collision with debris during take-off/landing or in flight. This article provides an analysis of the impact resistance capability of graphene doped T700 (T700G) multilayer composite, when subjected to steel projectile impacts. Test coupons with 300×300 mm were impacted by steel spherical projectiles, with impact energies ranging from 34 J to 338 J, using a compressed air operated cannon. Test data, such as impact and absorbed energy were determined through impact and residual projectile velocity, acquired using ballistic chronograph and two high speed cameras. Damage assessment was performed using non-destructive techniques such as Ultrasonic testing before and after impact test. Through modelling and simulation, using ABAQUS/Explicit, and recording the change of projectile velocity, the energy loss of projectile is calculated, and the impact resistance is judged together with damage extent. T700G has similar impact resistance to AL2024, underperforming when impacted by larger projectiles and presenting an overall higher damaged area.

The impact‐induced deformation characteristics of polycarbonate panels

AbstractIn this study, the investigation of damage caused by a spherical steel projectile on the polycarbonate (PC) panels has been undertaken both numerically and experimentally. The material properties are obtained from both static and dynamic tests. High‐velocity impact experiments are performed using a pressure‐based projectile launching system. The effect of panel curvatures and impact locations on the deformation are investigated experimentally. The impact locations are selected as both at the plate center and near the edge of the plate. A validation study is performed by analyzing the impact response of a PC plate as previously presented in the literature and subsequently comparing it with the results obtained. An analysis of the impact behavior of PC panels is carried out through numerical simulations using finite element program (LS‐DYNA). The effect of boundary conditions on the impact response is also investigated numerically. Plastic strains, von Mises stresses, dent depth, and energy absorption are obtained. It is indicated by the results that the deformation behavior of PC panels exhibits a strain rate dependence. Additionally, the deformation behavior is influenced by panel curvatures and boundary conditions, emphasizing the necessity to consider these factors in the design of structures, such as canopies made of PC panels.Highlights Provides a comprehensive understanding of polycarbonate behavior. Emphasizes the influence of impact locations and panel curvatures. Dent depth and stress rise with panel curvature, crucial for design considerations. Emphasizes the significance of strain rate and boundary condition in design.

Penetration resistance of corrugated hybrid structures with ceramic insertions against steel projectile impact

Ceramic-metal corrugated structures have attracted extensive attention because of their strong penetration resistance. In this study, the effects of geometric features and boundary constraints on corrugated structures consisting of a TC4 frame and five SiC ceramic prisms were explored by performing a series of ballistic tests. Deformation results were obtained using a three-dimensional scanner, and the dynamic response was observed using a high-speed imaging system. Numerical models of these tests were established and validated using experimental results. The results suggest that increasing the support and confining strength of ceramics delay their failure and increase their degree of breakage, thereby increasing the internal energy conversion ratio of the projectile and the energy absorption ratio of ceramics by 14% and 10%, respectively. Notably, a reasonable reduction in the strength of the frame partition expands the plastic deformation range of the frame and increases its energy absorption ratio by 10%. The conclusions of this study provide a reference for designing corrugated composite structures.

Numerical Study of the High-Speed Impact of a Steel Projectile on a Concrete Target

Numerical Study of the High-Speed Impact of a Steel Projectile on a Concrete Target

Experimental and numerical investigation on the compression after high-velocity impact behavior of composite laminates

Considering the differences in damage mechanism between high-velocity impact (HVI) and low-velocity impact (LVI), this study conducted HVI tests and compression-after-impact (CAI) tests to reveal the post-impact compression behavior of laminates manufactured by unidirectional prepreg tape and exposed a completely different mechanical response in residual strength compared to that of LVI. By controlling the impact velocity within the range of 200 m/s ̃ 380 m/s, three kinds of impact results were obtained, including un-penetrated and penetrated conditions. Different CAI damage morphologies can be observed in these laminates. In order to fully understand the CAI damage mechanism induced by different HVI events, a surface-based cohesive behavior and a CDM intralaminar damage model were implemented. In addition, a more complete picture of the compression behavior after HVI was observed through the simulation results, which is of great help in estimating the residual strength of post-impact laminates. However, the HVI damage was introduced through the spherical steel projectiles, and the sample size was determined based on ASTM D7137, which might be different factors from the application conditions.

High-velocity impact performance of AA 7475-T7351 aluminum square plates struck by steel projectiles: Assessing leakage limit velocity

This paper presents numerical and experimental findings of high-velocity impact tests conducted on thin AA 7475-T7351 aluminum plates subjected to the impact of small cubical and spherical projectiles. The investigation includes an examination of the influence of different impact angles, namely edge-on, corner-on, and face-on orientations, on the target performance. Following each impact test, the damaged plates underwent a leakage test, to determine the leakage threshold caused by the impact event. To gain a deeper insight into the failure modes and penetration mechanisms of thin-walled aluminum plates, finite element models were developed for various impact scenarios. The results revealed that both the shape and orientation of the projectile significantly impact the ballistic and liquid leakage limit velocities of targets. Notably, the cubical projectile exhibited lower ballistic and leakage limits than the spherical projectile. In terms of the leakage limit, a clear correlation was identified between the sharpness of the projectile's nose and leakage limit velocity. As the projectile's nose became sharper, the consistent trend was a decrease in leakage limit velocity i.e. the corner-on impact orientation (having the sharpest nose) exhibited the lowest leakage limit velocity, while the face-on impact orientation (having a blunt nose) displayed the highest leakage limit velocity. However, in contrast to the leakage limit velocity, a definitive relationship between the projectile nose sharpness and ballistic limit velocities was not observed. This is evident as the corner-on impact orientation, associated with the sharpest nose, registered the highest ballistic limit velocity, while the edge-on impact orientation, with an intermediate nose sharpness, recorded the lowest ballistic limit velocity.

Ballistic impact resistance of ultra-high-performance concrete (UHPC): A comprehensive experimental investigation and parametric analysis

This study explores the ballistic impact resistance of Ultra-High Performance Concrete (UHPC) through an extensive and detailed experimental investigation. This study will address various gaps related to the impact performance of UHPC. This investigation focused on understanding the ballistic resistance performance of UHPC based on (a) the influence of projectile/bullet parameters (hardness, velocity/energy, diameter, and nose shape), (b) the effect of hybrid fibers, (c) comparative analysis of the use of steel mesh and reinforcement bars and (d) effect of sub-zero temperature. In this parametric investigation, different types and shapes (flat, conical, and ogive) of hardened steel projectiles (diameter 12 and 18 mm) with impact velocities ranging from 103 to 182 m/s or impact energy ranging from 674 to 2103 J and UHPC slabs with thickness ranging from 36 to 100 mm was considered. Steel mesh and reinforcement bars at different spacing (with and without fiber UHPC) were also assessed, along with the effect of sub-zero temperature of −30 °C. The impact energy of the projectile and thickness of UHPC targets were statistically significant parameters affecting penetration depth in UHPC compared to other parameters with a p-value much less than 0.001. The Artificial Neural Network (ANN) model developed in the study could predict the penetration depth with reasonable accuracy (MAPE and RMSE were observed to be 7.69 and 12.12, respectively). The experimental results of this study will provide insights into the development of guidelines for using UHPC as a protective material, which can help ensure the safety and resilience of infrastructures in the face of potential threats.

Fracture behavior and mechanism of highly fragmented steel cylindrical shell under explosive loading

An in-depth understanding of the fracture behavior and mechanism of metallic shells under internal explosive loading can help develop material designs for warheads and regulate the quantity and mass distribution of the fragments formed. This study investigated the fragmentation performance of a new high-carbon silicon-manganese (HCSiMn) steel cylindrical shell through fragment recovery experiments. Compared with the conventional 45Cr steel shell, the number of small mass fragments produced by the HCSiMn steel shell was significantly increased with a scale parameter of 0.57 g fitted by the Weibull distribution model. The fragmentation process of the HCSiMn shell exhibited more brittle tensile fracture characteristics, with the microcrack damage zone on the outer surface being the direct cause of its high fragmentation. On the one hand, the doping of alloy elements resulted in grain refinement by forming metallographic structure of tempered sorbite, so that microscopic intergranular fracture reduces the characteristic mass of the fragments; on the other hand, the distribution of alloy carbides can exert a "pinning" effect on the substrate grains, causing more initial cracks to form and propagate along the brittle carbides, further improving the shell fragmentation. Although the killing power radius for light armored vehicles was slightly reduced by about 6%, the dense killing radius of HCSiMn steel projectile against personnel can be significantly increased by about 26% based on theoretical assessment. These results provided an experimental basis for high fragmentation warhead design, and to some extent, revealed the correlation mechanism between metallographic structure and shell fragmentation.

Numerical Prediction of Ballistic Performance of Thin Concrete Plate

This research explores the ability of 60[Formula: see text]mm thick reinforced concrete (RC) plates to resist impacts from ogive-nosed hard steel projectiles. The projectiles used in the present study have a diameter of 19[Formula: see text]mm, a length of 200[Formula: see text]mm, and a mass of 0.4[Formula: see text]kg impacted on the RC plates with incident velocities ranging from 92[Formula: see text]m/s to 161[Formula: see text]m/s. Numerical simulations were conducted using ABAQUS/Explicit finite element software to validate the experimental results. The Holmquist–Johnson–Cook (HJC) material model was employed to simulate the constitutive behavior of concrete, while the Johnson–Cook (JC) material model was used to simulate the material response of reinforcing steel bars. The residual velocities obtained from the simulations closely matched the actual experimental results, showing a polynomial correlation with the incidence velocities of the projectiles. Moreover, the experimentally and numerically determined ballistic limit for the 60[Formula: see text]mm thick RC plate was found to be 108[Formula: see text]m/s and 109.5[Formula: see text]m/s, respectively. In contrast, the ballistic limit calculated using empirical mathematical expressions was 107.4[Formula: see text]m/s. This alignment between predicted, calculated, and actual ballistic limits underscores the reliability and accuracy of both numerical and empirical approaches.

High-velocity impact damage by projectile and tension after impact behavior at 1300 ℃ for SiC/SiC with environment barrier coating

The research on the high-speed & low-energy impact under millimetre sized projectile and residual strength under high temperature are rare for SiC/SiC with Environmental Barrier Coatings (EBC). The impact of 2 mm steel projectiles at the speed of 177.5 m/s–252.7 m/s was studied for EBC(Si/Yb2Si2O7/Yb2SiO5)-SiC/SiC with Chemical Vapor Infiltration (CVI) process. The tensile test at 1300 ℃ was conducted on an inert gas protection testing machine. The optical microscope, Scanning Electronic Microscope(SEM), μCT were used to observe the impact and tension after impact(TAI) damage. The results shows that projectile impact has strong effect on EBC peeling, SiC/SiC damage and fracture, and residual-tension strength at 1300 ℃. And the threshold values of impact velocity or energy are different for them. Furthermore, an analysis method for damage evolution by the attachment quantity of oxide was found for EBC-SiC/SiC composites.

High-velocity impact experiments and quantitative damage evaluation for finite ultra-high-performance concrete targets

In this work, we aim at improved characterization of target damage occurring as the result of projectile impact against ultra-high-performance concrete (UHPC). For this purpose, we present the results of high-velocity impact experiments with spherical steel projectiles and finite-thickness UHPC targets of approximately 115 MPa compressive cylinder strength in the impact velocity range from approximately 600 m/s to 1500 m/s. The data set obtained from these experiments includes residual projectile velocities as well as qualitative and quantitative information on damage. Quantitative damage information is mainly extracted from digital 3D post mortem targets, which are produced by 3D-scanning. For all damage quantities, a dependence on the impact velocity and the target thickness is discussed and used to provide possible explanations for the origin of the particular type of damage. The large data set presented in this work can constitute the basis for a comprehensive and quantitative verification and validation of analytical, empirical, and numerical models that describe the perforation of UHPC targets in the investigated impact velocity range.