Penetration Depth Of Projectile Research Articles

Numerical Study of Shape and Density Effect on Semi-Infinite Metallic Target Under Hypervelocity Impact

Numerical investigations are conducted to examine the penetration depth of ellipsoid-shaped projectiles into semi-infinite aluminum targets under conditions of hypervelocity impact. These results are then compared against empirical equations developed by various researchers for spherical projectiles. The semi-infinite aluminum target, sized at [Formula: see text][Formula: see text]mm, is composed of Al7075-T651. The projectiles are fashioned from Al-7075-T651, steel, and boron carbide. The projectile’s shape factor was determined using the L/d ratio, specifically for the symmetrical ellipsoidal shape. Employing Ansys Autodyn, a 3-dimensional finite element model (FEM) is created and calibrated using existing experimental findings from the literature. The validation utilized the Johnson–Cook (JC) and Johnson–Holmquist (JH-2) material models for both the targets and projectiles. These validated models are subsequently employed to analyze how the ellipsoid projectile’s shape and density influenced their interaction with the semi-infinite targets. Furthermore, the investigation also encompassed an analysis of the resulting crater shapes generated by the hypervelocity impact of both metallic and nonmetallic projectiles. It is observed that for a definite SF, max[Formula: see text] depth of penetration is observed due to steel project as compared to boron carbide and aluminum projectile. Both the diameter of the crater and the height of the bulge ([Formula: see text] are directly proportional to the impact velocity and density of projectiles, and inversely proportional to SF. However, for a particular material and impact velocity of the projectile, in the case of [Formula: see text], there are no clear-cut observations displayed it seems like a mixed variation.

The maximum penetration depth of hypervelocity projectile penetration into concrete targets: Experimental and numerical investigation

With the employment of the Kinzhal hypervelocity missile in warfare, evaluating the penetration damage effect especially the penetration depth of hypervelocity weapons has become a hot topic. The maximum penetration depth is one of the most important concerns for protective engineers, however, which is still an open question due to the lack of penetration data. A combined experimental and numerical investigation on projectile hypervelocity penetration into concrete targets is presented in this study. Hypervelocity penetration tests were first carried out by launching projectiles with various length-to-diameter (L/D) ratios penetrating concrete targets, where the striking velocities ranged from 1462 m/s to 2891 m/s. Combined with our previous penetration data, a complete variation tendency of penetration depth is depicted, demonstrating the existence of the maximum penetration depth. Then the corresponding numerical models are developed and validated. Based on the numerical results, the three stages during hypervelocity penetration are identified, and the variation tendency of the penetration depth is clarified. After that, the influence of the properties of projectile and target on the maximum penetration depth and corresponding critical striking velocity are numerically investigated. Finally, empirical formulas are established to quantify the influences of these parameters on the critical striking velocity and penetration depth. The research results can provide important references for designing protective structure against hypervelocity weapons.

Discussion on Static Resistance of Granite under Penetration.

A total of 9 tests were carried out with 30 mm and 78 mm caliber scaled projectiles penetrating into granite targets. The penetration depth, crater diameter, and mass loss rate were examined and discussed. The results indicate that the dimensionless penetration depth of large-caliber projectiles is 20% greater than small-caliber projectiles. Based on the description of static resistance Ra in the Forrestal semi-empirical formula, the size effect of dimensionless penetration depth can be attributed to the size effect of static resistance Ra, and it can be seen that the penetration static resistance of projectile A is 40% higher than that of projectile B. Numerical simulations of projectile penetration into granite targets were conducted using the finite element program ANSYS/LS-DYNA. In terms of penetration depth and crater damage, the numerical simulation results agree well with the test data. This suggests that the selection of parameters was reasonable. The influence of compressive strength, projectile striking velocity, mass, diameter, and caliber-radius-head (CRH) ratio on the static resistance Ra were studied by RHT model parameterization. Based on the numerical results from the parametric study, an empirical formula was derived to predict the static resistance Ra.

Using the Simplified Concrete Damage Plasticity Model in Studying the Penetration Depth in Concrete

This paper, with the simplified concrete damage plasticity (SCDP) model, studying the penetration depth of steel projectile in the concrete block by Abaqus software. Comparing the results calculated by Abaqus software with the Modified NDRC formula to check the reliability of the computational model and material model. From there, studying the effect of concrete strength on penetration depth in concrete B20, B30, B40, B50.

The role of granular buoyant force of projectile in determining the penetration depth

This research develops a new formulation for final penetration depth of projectile on granular material. Although several relevant researches exist to estimate final penetration depths of blunt projectiles, estimation of final penetration depth of sharp projectiles is still difficult. Direct application of the formulation of blunt projectile cannot be applicable for sharp projectile. It is possible to employ heuristic and empirical formulations to predict the penetration depth of projectiles. Through several experimental studies, this research, however, finds out that buoyant force of sharp projectiles can be included in the existing formula for the final penetration depth of blunt projectiles. In order to verify the hypothesis, first of all several experiments with cylinder and ball were carried out to validate the existing theory. After sharp projectiles are experimented, the effect of the buoyant force is formulated as initial penetration depth. By adding this initial penetration depth determined by balancing between the buoyant force and weight, it is possible to adjust the existing formula for sharp projectiles. To show the validity of the present formulation, several cone shape projectiles are modeled and tested.

A Machine Learning Model for the Prediction of Concrete Penetration by the Ogive Nose Rigid Projectile

In recent years, research interest has been revolutionized to predict the rigid projectile penetration depth in concrete. The concrete penetration predictions persist, unsettled, due to the complexity of phenomena and the continuous development of revolutionized statistical techniques, such as machine learning, neural networks, and deep learning. This research aims to develop a new model to predict the penetration depth of the ogive nose rigid projectile into concrete blocks using machine learning. Genetic coding is used in Python programming to discover the underlying mathematical relationship from the experimental data in its non-dimensional form. A populace of erratic formulations signifies the rapport amid dependent parameters, such as the impact factor (I), the geometry function of the projectile (N), the empirical constant for concrete strength (S), the slenderness of the projectile (λ), and their independent objective variable, X/d, where X is the penetration depth of the projectile and d is the diameter of the projectile. Four genetic operations were used, including the crossover, sub-tree transfiguration, hoist transfiguration, and point transfiguration operations on supervised test datasets, which were divided into three categories, namely, narrow penetration (X/d < 0.5), intermediate penetration (0.5 ≤ X/d < 5.0), and deep penetration (X/d ≥ 5.0). The proposed model shows a significant relationship with all data in the category for medium penetration, where R2 = 0.88, and R2 = 0.96 for deep penetration. Furthermore, the proposed model predictions are also compared with the most commonly used NDRC and Li and Chen models. The outcome of this research shows that the proposed model predicts the penetration depth precisely, compared to the NDRC and Li and Chen models.

Misleading Entry Wounds From Atypical Bullet Behavior.

Some pistol bullets exhibit atypical wound ballistic behavior that can result in misleading and misinterpreted entry gunshot wounds. We demonstrate the atypical performance and behavior of these bullets using (1) high-speed videography of projectiles penetrating, perforating, and exiting soft tissue simulants; (2) Doppler radar tracking throughout simulated wound production; (3) downrange witness panels to record postperforation bullet orientation during a secondary impact; (4) laser tracking to assess and compare postperforation bullet deflection; (5) evaluation of "bullet wipe" around entry bullet holes in a victim's clothing; and (6) projectile penetration depth for differentiating primary from secondary gunshot wounds. Truncated cone and certain flat-point full-metal-jacketed pistol bullets in the 3 most common calibers of 9 mm, .40 caliber, and .45 caliber typically perforate the victim with little or no yawing, producing straight wound tracks and continuing to travel nose forward upon exiting. Any secondary gunshot victim downrange sustains a normal-appearing entry wound. Common pistol bullets exiting gunshot victims are typically destabilized and enter a yawing or tumbling flight, resulting in entry wounds that appear as typical, first strike entry wounds when in fact, they are secondary gunshot wounds. However, some bullets retain their nose-forward flight after emerging from a gunshot victim. These secondary but normal-appearing, round-shaped entry wounds may be erroneously identified as direct, primary strikes.

Mass Loss and Penetration Depth of Hypervelocity Projectiles

Numerous investigations recorded a dramatic decrease in penetration depth at hypervelocity. The decrease is due to the severe mass loss of the projectile. The mechanics of mass loss are complicated, so the entirely theoretical model is still absent. In this paper, we derive a semitheoretical formula for mass loss by solving the equation of motion of the projectile during penetration. The result shows that the decrease in projectile mass at hypervelocity accords with the power law. Furthermore, we obtain a continuous formula for depth of penetration in the entire velocity domain. The theoretical results agree well with experimental data. The formula for the critical velocity of depth decreasing is also obtained as a by-product of the solving procedure.

Penetration dynamics of a carbonate sand: A synchrotron phase contrast imaging study

Penetration into granular materials such as carbonate sand is of fundamental importance to granular physics, and impact and civil engineering, but research along this line suffers considerably from the lack of direct experimental observations. Here we investigate such penetration dynamics of carbonate sand using a vertical gas gun implemented with in situ, high-speed, synchrotron-based X-ray phase contrast imaging. The experiments yield the first direct observation on the penetration dynamics (projectile trajectory/velocity) and particle-scale deformation in real or natural granular materials during sphere penetration, at high temporal and spatial resolutions. The particle displacement fields around the projectile are obtained via X-ray digital image correlation, and the ejecta velocity fields, with particle image velocimetry. Effects of the moisture content and container size on the penetration process are discussed. The enhanced cohesion between wet particles results in particle clustering during splash and a smaller amount of ejecta. Therefore, the particle rearrangement is limited and the projectile penetration depth is smaller. A small container size confines the lateral movement of particles and yields a much more pronounced compaction of particles beneath the projectile, which results in a smaller penetration depth as well.

Comparison between computed tomography and silicone-casting methods to determine gunshot cavities in ballistic soap.

Current methods used in terminal ballistics to determine the volume of temporary cavities created by projectiles in soft tissue simulants (such as ballistic soap) usually involve silicone-casting to obtain the cavity moulds. However, these methods have important drawbacks including their little sensitivity and precision, besides the fact that they are destructive. Imaging techniques such as computed tomography (CT) might not only overcome those limitations but also offer useful tools for digitally reporting the scientific results. This work accomplished the 3D digital reconstruction of the cavities created by different projectiles in ballistic soap blocks. This way, the total volume of the cavities, the projectile penetration depths, and other measurements were determined, rendering better capabilities when compared to the current silicone method. All these features were achieved through the CT analysis and 3D Slicer imaging software. In addition, it is worth mentioning that the method can preserve the evidence by digitally obtaining, signing, and storing the infographic videos displaying the 3D-reconstructed cavities. Graphical abstract.

Role of particle shape in determining tensile strength and energy release in diametrical compression of natural silica grains

Extensive particle fracture has been noticed in projectile penetration tests. However current models for predicting projectile penetration depths do not consider particle fracture. Therefore, in order to understand the role of particle shape on single grain strength and the subsequent comminution process, single grain crushing tests on sand grains of different shapes and sizes were performed. High-resolution, three dimensional images of grain surface, were created using confocal microscope and fracture of the grains were captured with high-speed imaging. Acoustic emissions during single grain crushing was used to estimate the energy released during grain fracture. It was found that local stress fields influence particle strength and in natural granular material surface flaws maybe the critical flaw causing fracture. The estimated critical flaw size causing fracture were submicron in size. The mass specific fracture energy increased with increasing failure stress and decreasing particle size and is significantly greater than that computed from pure diametrical breaking. Except for large angular grains, mass specific energies for different shapes were similar. Angular sands required multiple events to break. The outcome of this work can be utilized in geomechanics to understand the comminution process and in power industry to estimate the energy required for comminution.

IMPACT RESISTANCE OF CERAMICS IN A NUMERICAL EXPERIMENT

A series of computations based on experimental data on the depth of projectile penetration into targets is performed for verification of parameters of ballistic stability of plates made of Al2O3, B4C, and SiC ceramics. Interaction of a projectile with a steel core and a target made of an aluminum alloy with a variable-thickness ceramic plate positioned ahead of the target is simulated. The computed results are compared with experimental data for various ceramic targets 1–5 mm thick and projectile velocities of 810–850 m/s.

Tip cross-sectional geometry predicts the penetration depth of stone-tipped projectiles

Understanding prehistoric projectile weaponry performance is fundamental to unraveling past humans’ survival and the evolution of technology. One important debate involves how deeply stone-tipped projectiles penetrate a target. Theoretically, all things being equal, projectiles with smaller tip cross-sectional geometries should penetrate deeper into a target than projectiles with larger tip cross-sectional geometries. Yet, previous experiments have both supported and questioned this theoretical premise. Here, under controlled conditions, we experimentally examine fourteen types of stone-tipped projectile each possessing a different cross-sectional geometry. Our results show that both tip cross-sectional area (TCSA) and tip cross-sectional perimeter (TCSP) exhibit a strong, significant inverse relationship with target penetration depth, although TCSP’s relationship is stronger. We discuss why our experimental results support what is mathematically predicted while previous experiments have not. Our results are consistent with the hypothesis that when stone tip cross-sectional geometries become smaller over time in particular contexts, this evolution may be due to the selection of these attributes for increased penetration.

Modeling micro-particles impacts into ballistic gelatine using smoothed particles hydrodynamics method

Investigating high-speed microparticle impact responses into soft tissue is essential to several fields such as medicine and biology with technological applications like transdermal delivery of pharmaceuticals. The understanding of the physical process involved in such a phenomenon is complex and few experimental tools are available to study high-velocity microparticle penetration in soft tissues, generally substituted by simulants like gels in the literature. One way to overcome these issues is to use numerical simulation as an efficient way of investigation, but also include difficulties such as accurate models for materials properties, microscale computation, and mathematical formulations. As the earliest meshless method, Smoothed Particles Hydrodynamics (SPH) has been applied in solid dynamics because of its great potentials in simulating extremely large deformation and perforation of targets by various projectiles. This paper develops an original numerical model based on SPH to study the dynamical phenomena during microscale impact of spheres into ballistic gelatin (BG), a common human tissue surrogate. By simulating a series of particle penetrations into 10 wt% BG initial velocities, the projectile trajectories and penetration depths in gelatin are investigated. The effects of the gelatin’s elastic modulus in ballistic impact are also studied. The numerical results show that this numerical model appears to be an promising approach to simulate high-velocity microparticle penetrating ballistic gelatine materials.

Projectile penetration of reinforced concrete considering the effect of steel reinforcement: Experimental study and theoretical analysis

In this study, experiments in which projectiles penetrated into plain and reinforced concrete targets were conducted by controlling single variables for a differential experimental design including projectile impact locations, reinforcement arrangements, reinforcement buried depths, and reinforcement bonding conditions. Based on cavity expansion theory and the dynamic response analysis of the steel reinforcement, a reinforced concrete target penetration resistance model was established. The accuracy of the model was verified using the experimental data, and the influence of the steel reinforcement arrangement on projectile penetration was analyzed. The results show that the reinforcing steel bonding effect exert an indirect resistance while the impact of the projectile with the reinforcement exert a direct resistance, which is different from direct penetration into concrete. The indirect and direct resistances against the projectile act to reduce penetration depth and target surface damage. The results calculated using the derived numerical method clearly describe the observed details of the projectile impact with the steel reinforcement, and are in good agreement with the experimental data. The indirect and direct resistances of the steel reinforcement were observed to be affected by the initial conditions of the projectile and the target including impact locations and reinforcement arrangements. It was found that increasing the reinforcement ratio and adopting a denser reinforcement arrangement can reduce the penetration depth of projectile, and better protecting the integrity of the target.

실험식을 통한 고속 관통자의 지반 관통 깊이 예측에 대한 연구

실험식을 통한 고속 관통자의 지반 관통 깊이 예측에 대한 연구

Replication of the Al/Ti Metal Intermetallic Laminates Using LS Dyna for Tungsten Alloy Penetrator Application

In this study, the simulation of the Al/Al3Ti metal intermetallic laminates was done using finite element analysis software LS Dyna, under high-speed impact loading using a tungsten projectile. These MILs were processed by diffusion bonding under the condition (575 °C, 4 MPa and 6 h), which was further annealed for 48 h. In LS Dyna, the projectile was fired at different velocities such as 900 m/s, 1200 m/s and 2000 m/s to varying angles of 0°, 30° and 60°. In each case, the penetration depth of the projectile and the number of layers damaged were found to understand the resistance offered by the MILs to the projectile. The time versus projectile penetration depth graph and the corresponding stress distribution in the MILs in each case were plotted to understand the extent of damage caused. Further, the velocity, energy and crack density distribution graphs were extracted from LS Dyna to understand in detail the journey of the projectile through the MIL. It was found that greater the angle of firing, the lesser the penetration depth of the projectile but at the cost of more damage to the layers up to which the projectile penetrated through the MIL.

Dynamic spherical cavity expansion analysis of concrete/rock based on Hoek-Brown criterion

Cavity expansion theory has been widely applied to predict the penetration depth of projectiles into geological materials, in which the yield criterion and the constitutive model are combined to describe the shear and compaction of the material, separately. For a precise description of the material behaviors in plastic for geological materials with varied compressive strength, in this present manuscript, the Hoek-Brown yield criterion and the Dilatant-Kinematic equation were introduced into the plastic region. A response region called elastic-cracking-dilatant-compaction region for concrete and rock was established. Then the effects of various parameters, including brittleness coefficient, material integrity coefficient and dilatant coefficient, on the relationship between cavity pressure and normal expansion velocity were discussed. Finally, a penetration depth formula of rigid projectiles into semi-infinite concrete and rock targets was established. It showed that, compared with the classical Forrestal model, the proposed model had a well-being as well as higher accuracy prediction of the penetration depth of concrete and rock materials with various strengths.

Spherical Cavity Expansion Approach for the Study of Rigid-Penetrator’s Impact Problems

In recent years, Spherical Cavity Expansion (SCE) theory has been extensively utilized to model dynamic deformation processes related to indentation and penetration problems in many fields. In this review, the SCE theory is introduced by explaining the different mathematical features of this theory, its solution, and a potential application to model the penetration of a rigid penetrator into a deformable target. First, a chronologically literature review of the most common models used to study this kind of penetration problems is introduced, focusing on the SCE theory. Then, the engineering model of penetration is presented using the SCE approach. The model is then compared and validated with some FE numerical simulations and with previous penetration results. It is concluded that this engineering model based on the SCE theory can be utilized to predict the projectile deceleration and penetration depth into the semi-infinite and finite targets impacted by rigid penetrators.

The influence of free water content on ballistic performances of concrete targets

During the last decades, the study of the influence of free water content on performances of concrete has been improved by numerous experimental works. It is believed that wet concretes exhibit much lower deviatoric strength capacity, higher volumetric stiffness, and more strain-rate sensitivity compared to dry concretes. In this paper, the Kong-Fang concrete model recently proposed (Int J Impact Eng 2018, 120: 60–78) is modified to capture the effect of free water content. Three major modifications are made respectively to the strength surface, dynamic increase factor (DIF), and equation of state of the original model to capture the influence of free water content mentioned above. The modified strength surface, DIF, and equation of state for wet and dry concretes are compared with experimental data and show good agreements. The modified Kong-Fang model is then implemented into the finite element code LS-DYNA through user-defined material model. Single element tests including biaxial compression and triaxial compression are firstly performed to validate the modified model at a material point level, where corresponding predictions are compared with experimental results and good agreements are obtained. The influence of free water content on ballistic performances of concrete is then systematically investigated with the modified model. The predicted time-histories of projectile velocity, deceleration, and penetration depth are well consistent with the experimental data. It is found that the wet concrete exhibits higher penetration resistance compared to a dry concrete reflected in a lower projectile residual velocity for perforation case and smaller penetration depth for penetration case.