Projectile Erosion Research Articles

A Novel Multi-Scale Ceramic-Based Array (SiCb+B4Cp)/7075Al as Promising Materials for Armor Structure.

Ceramic panel collapse will easily lead to the failure of traditional targets. One strategy to solve this problem is to use separate ceramic units as armor panels. Based on this idea, we propose an aluminum matrix composite using pressure infiltration, containing an array of ceramic balls, the reinforcement of which consists of centimeter-scale SiC balls and micron-scale B4C particles. Three different array layouts were designed and fabricated: compact balls in the front panel (F-C), non-compact balls in the front panel (F-NC), and compact balls inside the target (I-C). The penetration resistance properties were tested using a 12.7 mm armor-piercing incendiary (API). The results show that there are no significant internal defects, and the ceramic balls are well-bonded with the matrix composite. The F-NC structure behaves the best penetration resistance with minimal overall damage; the I-C structure has a large area of spalling and the most serious damage. Finite element simulation reveals that the ceramic balls play a major role in projectile erosion; in the non-compact structure, the composite materials between the ceramic balls can effectively disperse the stress, thereby avoiding the damage caused by direct contact between ceramic balls and improving the efficiency of ceramic ball erosion projectiles. Furthermore, it is essential to have a certain thickness of supporting materials to prevent spalling failure caused by stress wave transmission during penetration. This multi-scale composite exhibits excellent ballistic performance, providing valuable insights for developing anti-penetration composite armor in future applications.

Ballistic performance of optimised light weight composite armour

This research paper presents a comprehensive investigation into the response of a 3D finite element model when subjected to 7.62 AP projectiles. The study utilises Hetherington's armour composite equation and incorporates the Johnson-Holmquist material model to analyse the strength and failure criteria of the ceramic and Kevlar/epoxy components, respectively. The results highlight the remarkable resilience of the composite armour, demonstrating its ability to withstand projectile velocities up to 1500 m/s. However, as the ballistic velocity limit increases, the armour experiences significant damage, including projectile erosion and panel delamination. Through numerical simulations and advanced modelling techniques, the paper thoroughly explores the failure modes and energy absorption characteristics of composite armour systems under projectile impact. It investigates key parameters such as velocity, acceleration, kinetic energy, internal energy, pressure distribution, displacement, and damage progression. The analysis reveals a progressive decrease in kinetic energy as the projectile interacts with the armour, underscoring the crucial role of energy absorption in preventing projectile penetration. Moreover, the impact velocity influences the distribution of internal energy within the composite armour, with higher velocities leading to greater energy absorption up to a threshold limit. The study also determines the ballistic limit velocity (V50) using the velocity history approach and validates the findings with existing literature. Overall, the research provides valuable insights into the limitations of composite armour and offers important recommendations for designing and improving materials to achieve superior ballistic protection. It emphasises the significance of reaching the maximum ballistic limit while maintaining a lightweight armour structure by optimising the total armour thickness. This study contributes to the advancement of armour technology and enhances our understanding of the behaviour of composite materials under high-velocity impacts. It offers valuable guidance for the development of more robust armour systems suitable for various defence and protection applications.

Evaluation of Projectile Penetration Position on Perforated Plate on Ballistic Resistance of Composite Sandwich Panels

This paper evaluates the performance of perforated plates in composite sandwich panel under high-velocity impact. The ballistic resistance of composite sandwich panels made of steel plate on the outer layer and the rubber on the middle layer was evaluated using experimental and numerical methods. The front plate is modified with 3 mm diameter of holes, and the distance between the holes is 10 mm. Experimental testing was carried out by firing a 9 mm full metal jacket projectile at a distance of 5 m and an angle of attack of 90° on the target. Experimental results and numerical simulations show that the position of the projectile penetration at the side of the hole in the composite panel stops the projectile velocity faster at 1.1619 x 10−4 s with a maximum energy absorption of 532.9 J than at center of hole and middle of four holes. The failure of the side of the hole penetration position is the asymmetrical deformation of the back plate due to changes in the penetration position of the projectile with the initial trajectory, fractural projectile core and brass jacket projectile erosion. The projectile penetrates the front plate due to plastic deformation, and rubber in the middle layer is pushed and perforated in the projectile direction, causing the back plate to form a bulge.

High-velocity impact study of an advanced ceramic using finite element model coupling with a machine learning approach

A numerical approach combining finite element modeling and machine learning is used to inform the material performance of an alumina ceramic tile undergoing high-velocity impact. In this study, the alumina ceramic tile is simulated by incorporating a user-defined Johnson–Holmquist–Beissel (JHB) material model within the framework of smoothed particle hydrodynamics (SPH) in LS-DYNA finite element software. The implementation of the JHB model is verified by comparing equivalent stress–pressure responses through a single element simulation test. After implementation, the computational framework is simulated across our chosen range of conditions by matching the results from both plate impact experiments and ballistic testing from the literature. The computational model is then used to generate training data sets for an artificial neural network (ANN) to predict the residual velocity and projectile erosion for an alumina ceramic tile undergoing high-velocity impact in the SPH framework. The ANN is then used to perform a sensitivity analysis involving exploring the effect of mechanical properties (e.g., strength and shear modulus) and impact simulation geometries (e.g., thickness of ceramic tile) on material performance (i.e., residual projectile velocity and erosion). Overall, this study shows the capability of the FEM-ANN approach in studying the high-velocity impact on ceramic tiles and is applicable to guide the structural-scale design of ceramic-based protection systems.

Experimental and Theoretical Study of high-velocity penetration of long rod projectiles into sand

Results of computations with the use of improved modified Alekseevskii-Tate theory (IMATT) are compared to experimental data on high-velocity penetration of long rod projectiles into sand in the impact velocity range of V_0=0.5-3.5 km/s. Projectiles were made of three different metals: M1 copper, WNZh tungsten heavy alloy and 30KhGSA steel. The value of hardening coefficient k in the linear dependence of the projectile material yield on pressure could be determined using IMATT and experimental data on dependence of differential penetration coefficient K on the penetration velocity. At penetration in regime of the hydrodynamic erosion of projectile, differential penetration coefficient K could be approximated just by dependence on the ratio of the impact velocity of penetration to the value of the critical velocity, above which the projectile deforms plastically during penetration. The values of the critical velocity may differ for specific projectile material properties as well as the density and the humidity of sand. Keywords: high-velocity penetration, plastic deforming, yield, hydrodynamic erosion, Alekseevskii-Tate theory, experiment.

Экспериментальное и теоретическое исследование высокоскоростного проникания длинных стержневых ударников в песок

Results of computations with the use of improved modified Alekseevskii-Tate theory (IMATT) are compared to experimental data on high-velocity penetration of long rod projectiles into sand in the impact velocity range of V0=0.5-3.5 km/s. Projectiles were made of three different metals: M1 copper, WNZh tungsten heavy alloy and 30KhGSA steel. The value of hardening coefficient k in the linear dependence of the projectile material yield on pressure could be determined using IMATT and experimental data on dependence of differential penetration coefficient K on the penetration velocity. At penetration in regime of the hydrodynamic erosion of projectile, differential penetration coefficient K could be approximated just by dependence on the ratio of the impact velocity of penetration to the value of the critical velocity, above which the projectile deforms plastically during penetration. The values of the critical velocity may differ for specific projectile material properties as well as the density and the humidity of sand.

A simplified and modified model for long rod penetration based on ovoids of Rankine

This paper proposes an alternative to the Alekseevskii-Tate model, denoted by AT, for erosion of a long rod penetrator. Specifically, the model uses simplified equations of the model for long rod penetration based on ovoids of Rankine developed in (Roisman et al., 2001). The resulting modified ovoid of Rankine model, denoted by MOR, proposes differential equations for the velocity of the projectile’s tail, the penetration velocity into the target, the erosion of the projectile’s mass and the penetration depth, as well as an algebraic equation to determine the point of separation of the target material from the projectile’s surface. The MOR model uses shock conditions to determine the initial value of the penetration velocity and it predicts the initial transient decrease of this velocity to its value for quasi-steady-state projectile erosion. This model also includes an expression for the crater diameter which predicts values close to experimental data. Relative to the AT model, the MOR model introduces a single empirical parameter in a modified evolution for mass erosion which significantly influences the penetration depth without affecting the crater diameter. This parameter models the interface between the deforming projectile’s nose and its rigid tail where the projectile’s tail is rapidly decelerating due to mushrooming and mass erosion. Its value is determined by comparing model predictions of the penetration depth with experimental data. Future research is needed to replace this empirical parameter with an analytical model and to better model the termination process of penetration.

Hemispherical nosed steel projectile high-speed penetration into aluminum target

Terminal ballistic performance of high-strength projectiles penetrating into metallic targets is mostly concerned by both weapon and armor designers. Most existing works are concentrated on the rigid-eroding penetration regime, and limited studies have addressed the rigid-deforming-eroding penetration regime. In this paper, nineteen shots of hemispherical nosed D6A steel projectiles penetration test on 5A06-H112 aluminum targets is conducted with a wide range of velocities (696m/s–1870m/s). The non-monotonic dependence of depth of penetration (DOP) on the impact velocity is observed, which successively corresponds to the three penetration stages, i.e., rigid projectile penetration, deforming projectile penetration without eroding and eroding projectile penetration. Then, for the non-monotonic rigid-deforming-eroding projectile penetration regime, the applicability of the existing six classical theoretical models for both rigid and eroding projectile penetrations is evaluated. Furthermore, the transition velocities (the upper limit of rigid penetration and the lower limit of eroding penetration) are discussed and an empirical judgement criterion for the occurrence of non-monotonic dependence is proposed. Finally, by conducting the dynamic compression test, quasi-static tension test under varying temperature, etc., the Johnson-Cook model parameters for the present target and projectile are calibrated and validated by numerically simulating the present test.

Theoretical analysis of projectile-target interface defeat and transition to penetration by long rods due to oblique impacts of ceramic targets

Integrated with related investigations, the present manuscript conducts systematical theoretical analysis on the interface defeat (the phenomenon where an impacting eroding projectile flows radially outward along the surface of target without any significant penetration) of long rods under the oblique impacts onto ceramic targets, and related comparison with the normal impact is also carried out. By taking the influence of obliquity angle into account, the corresponding formulae for the velocity decay and the mass erosion of long rods with time are deduced out, and the kinetic energy loss is further discussed. Moreover, the transition from interface defeat to penetration is analyzed in detail. The variation characteristic of critical impact velocity range with the increase of obliquity angle is discussed, and the critical transition time is deduced considering the damage and failure characteristics of the ceramic target. Furthermore, the corresponding theoretical expressions are formulated. Finally, some suggestions for optimizing the design of ceramic target are given based on related analysis.

Projectile penetration into mortar targets with a broad range of striking velocities: Test and analyses

Eighteen shots of flat nosed cylindrical 45# steel projectiles penetrating into mortar targets with cubic compressive strength of 50MPa are conducted, where the striking velocities are ranged from 510m/s to 1850m/s. By examining the damages of targets, linear dependences of the cratering diameter and depth on the initial striking velocity, as well as the cratering volume on the initial kinetic energy of projectile are found. Three penetration regimes, i.e., rigid projectile penetration, deforming projectile penetration without eroding and eroding projectile penetration are observed successively with the increase of striking velocity. Furthermore, the experimental depths of penetration are compared with the predictions of our recently established rigid and eroding penetration models based on an extended dynamic cavity expansion model (Kong et al. 2017). The rigid projectile penetration model is further validated, and the eroding projectile penetration model is further justified, improved and validated by considering the succeeding rigid penetration stage. Finally, the analytical expressions for the upper limit velocity of rigid projectile penetration and the lower limit velocity of eroding projectile penetration are given and validated, respectively.

Rigid and eroding projectile penetration into concrete targets based on an extended dynamic cavity expansion model

A hyperbolic yield criterion and Murnaghan equation of state were introduced to describe the plastic behavior of concrete material under projectile penetration, and an extended dynamic cavity expansion model was proposed. Then, a unified one-dimensional resistance of concrete target to projectile penetration was formulated, in which the projectile nose shape influences were taken into account by three non-dimensional coefficients. Furthermore, combined with the Newton's second law and Alekseevskii-Tate equations, both rigid and eroding projectile penetration models into concrete targets were established. By comparing with the existing tests data as well as prediction results of previous model based on the linear yield criterion and equation of state, the proposed models were verified. Besides, a series of practical parameters of hyperbolic yield criterion and Murnaghan EOS for the extended dynamic cavity expansion model were given and verified.

Flash X-ray cinematography analysis of dwell and penetration of small caliber projectiles with three types of SiC ceramics

Abstract In order to improve the performance of ceramic composite armor it is essential to know the mechanisms during each phase of the projectile–target interaction and their influence on the penetration resistance. Since the view on the crater zone and the tip of a projectile penetrating a ceramic is rapidly getting obscured by damaged material, a flash X-ray technique has to be applied in order to visualize projectile penetration. For this purpose, usually several flash X-ray tubes are arranged around the target and the radiographs are recorded on film. At EMI a flash X-ray imaging method has been developed, which provides up to eight flash radiographs in one experiment. A multi-anode 450 kV flash X-ray tube is utilized with this method. The radiation transmitted through the target is then detected on a fluorescent screen. The fluorescent screen converts the radiograph into an image in the visible wavelength range, which is photographed by means of a high-speed camera. This technique has been applied to visualize and analyze the penetration of 7.62 mm AP projectiles into three different types of SiC ceramics. Two commercial SiC grades and MICASIC (Metal Infiltrated Carbon derived SiC), a C-SiSiC ceramic developed by DLR, have been studied. The influences, not only of the ceramic but also the backing material, on dwell time and projectile erosion have been studied. Penetration curves have been determined and their relevance to the ballistic resistance is discussed.

Comparative Analysis on the Interface Defeat between the Cylindrical and Conical-Nosed Long Rods

Based on the Alekseevski-Tate model, the present manuscript theoretically analyzes the interface defeat of cylindrical and conical-nosed long rods in their penetration process and the corresponding formulae of velocity decay and mass erosion of projectile are deduced out. In particular, with regarding the truth of quasi-static tail velocity of long rod in the interface defeat, the simplified and explicit analytical expressions of the dominated parameters with time, e.g. the tail velocity, eroded length and residual mass of the rod, are all formulated. Finally the kinetic energy loss of long rod is analyzed, and the effects of velocity decay and rod erosion on the kinetic energy loss of long rod are discussed. Especially, regarding the conical-nosed long rod, the effect of half apex angle on the kinetic energy loss is also analyzed.

Normal impact of hard projectiles on concrete targets

AbstractThis research study involves obtaining an analytical model for the perforation of unreinforced concrete targets by a hemispherical hard projectile. Dynamic cavity expansion theory and the reflection of compressive waves from the end of the concrete targets are used for developing the analytical model. The effect of the friction coefficient is also investigated in the analysis. Numerical modelling of the problem has been performed in LS‐DYNA code for validating the analytical results. Johnson‐Holmquist concrete and rigid material models have been employed for the concrete and the projectile respectively. The impact velocity range considered in this work is between 250 and 850 m/s. No projectile erosion is considered in this range. The analytical results have been compared with numerical results and show good agreement with numerical simulations.

Analysis of resistance of concrete target against penetration of eroding long rod projectile regarding flow field around the projectile tip

Precise understanding of concrete target behavior when subjected to high velocity impact of an eroding projectile involves analysis and studying the plastic flow field around the penetrating projectile. In this paper, the flow field around an eroding projectile is reviewed and the main equations of it are presented. Assuming viscoplastic behavior and solving these equations results in determination of the thickness of plastic layer ahead of penetrating projectile. Results show that the strength of the target is proportional to the size of the incompressible zone. Furthermore, there is a direct relation between penetration velocity and pressure gradient at the beginning and end of the incompressible zone; the lesser the pressure gradient the smaller the penetration velocity which means the higher resistance of the target against penetration. Comparison between the results of the presented analysis and experimental data corroborates acceptable accuracy of the model.

Analysis of perforation process into concrete/metal targets by rigid projectiles

In this article, a semi-analytical model has been developed for perforation of a hard projectile into a single- and two-layer concrete targets. The model is based on the dynamic cavity expansion theory and the reflection of compressive waves from the end of the concrete targets. The effect of friction coefficient is also investigated in the analysis. Numerical modeling of the problem has been performed in LS-DYNA code. Holmquist–Johnson–Cook, plastic kinematic, and rigid material models have been employed for the concrete, the backing plate, and the projectile, respectively. The impact velocity range, considered in this study, is between 300 and 800 m/s. No projectile erosion is considered in this velocity range. The analytical results of the investigation for both single- and two-layer concrete targets are in a good agreement with numerical simulations and experimental data.

An energy-based model for ballistic impact analysis of ceramic-composite armors

An analytical model is presented for the ballistic impact behavior of ceramic-composite armors. The model is based on wave theory and energy balance between the kinetic energy of the projectile and the energy absorbed by different mechanisms. The armor analyzed consists of front composite cover layer, ceramic plate, rubber layer and the composite backing plate. The projectile is cylindrical. The major damage and energy-absorbing mechanisms are compression of the target directly below the projectile, compression in the surrounding region around the point of impact, formation of ring cracks and radial cracks in the ceramic leading to tensile failure, shear plugging, pulverization of the ceramic, tension in the yarns, delamination and matrix cracking in the composite, bulge formation on the back face of the composite backing plate and friction between the target and the projectile. Projectile erosion and deformation are also considered. Kinetic energy, velocity and deceleration of the projectile, distance traveled by the projectile and the contact force are presented as a function of time. Ballistic limit velocity, contact duration and damage progression are also given. Further, solution procedure is presented for the study of ballistic impact behavior of ceramic-composite armors. Analytical predictions are validated with the experimental results. Finally, performance of a typical ceramic-composite armor is presented.

The influence of confinement on the penetration of ceramic targets by KE projectiles at 1.8 and 2.6 km/s

This paper presents the results of scale size experiments using a tungsten-alloy long-rod projectile fired against 97.5% Al 2O 3 ceramic targets at 1.8 and 2.6 km/s. Two targets were used, one having lateral steel confinement; the other without. The projectile overmatched the target, and residual projectile length and velocity were recorded using ballistic-syncro photography. Flash radiography was used during penetration of the unconfined target to obtain the penetration velocity. Manganin pressure gauges were also used to obtain additional data on the response of the ceramic target during penetration. Results from the eight experiments indicate that the confinement reduced the residual energy of the projectile at both impact velocities. Expressed in terms of the projectile impact energy, 55–56% was lost in the unconfined target at 2.6 km/s compared with 60% for the confined design. The same trend was found at 1.8 km/s with 68% and 72–73% for the unconfined and confined, respectively. Predictions using the QinetiQ GRIM2D hydrocode and a simplified form of the Johnson–Holmquist ceramic material model agreed well with the experiments for three out of the four test configurations. The predicted projectile erosion and retardation against the confined target at 1.8 km/s was excessively high. Analytical predictions using the Tate modified Bernoulli equation also gave reasonably accurate predictions for three of the tests, but values for the Tate target ‘strength’ extracted from experiments using a different target configuration were not accurate for the target design used in this paper.

Analysis of the terminal phase of penetration

The terminal phase, or Phase 3, of penetration is investigated using numerical simulations. Results of the first set of simulations, for zero-strength tungsten-alloy projectiles into armor steel at velocity of 1.5, 3.0, and 6.0 km/s are reported here. For these simulations, the mechanisms for Phase 3 penetration are limited to the transient deceleration of the eroding projectile and after-flow, the extension of penetration after the projectile has fully eroded. It is found that for projectile L/D ≤ ∼2, there is effectively no steady-state penetration (Phase 2) and penetration is dominated by Phase 3. For projectiles of L/D ≥ 3, steady-state penetration is achieved. For L/ ≥ 3, the deceleration of both the nose and tail of the projectile are essentially independent of L/D. For L/D ≥ 3, the target penetration associated with Phase 3 is found to increase with impact velocity approximately as P 3 /D V 1 . 0 . After-flow as a separate, identifiable mechanism could not be discerned in the results. We therefore question whether the phenomenon of after-flow, as usually defined, exists; rather, projectile deceleration and crater depth growth are intimately coupled.

A study of erosion through plate targets

Computational experiments have been performed to study projectile erosion during the various phases of perforation of finite thickness steel plate targets. Studies were conducted at several impact velocities for thin, three-plate, spaced targets separated by one plate thickness. For tungsten alloy projectiles (Wi-Ni-Co), it is shown that the primary phase erosion is quantitatively similar irrespective of impact velocity and results in a perforation efficiency, η p , normally attained only in semi-infinite target, hypervelocity penetration cases. The indifference with respect to velocity is due to the close proximity of the plate rear surface and results in a similarity of the instantaneous perforation efficiency profile through the plate thickness. Further, it is shown that values for the semi-infinite penetration efficiency, as a function of impact velocity, vary during the penetration event and only attain their respective reference values at late-time. In short, P/L is not as velocity differentiated at early-time as it is at late-time. Bulge phase and residual phase erosion results are consistent with the notion that these erosion mechanisms are sensitive to impact velocity. For comparative purposes, simulations were also performed for a single-plate, equivalent line-of-sight (LOS) thickness plate target. In this case, the primary phase only perforation efficiency increases slightly with impact velocity. Taken together, perforation efficiency results for these two finite thickness plate targets and archival data for the penetration efficiency of semi-infinite thick targets suggest a small geometric effect when corresponding data are compared.