Projectile Nose Research Articles

A novel dynamic cavity expansion model to predict the resistance of reactive powder concrete (RPC) against projectile impact

The dynamic cavity expansion (DCE) model is a commonly used analytical model to predict the resistance of concrete materials subjected to projectile impact. In this paper, a modified Griffith strength criterion was proposed for reactive powder concrete (RPC), which has a form easy to solve and can well capture the tensile, compressive and triaxial strength of RPC. Combined with the Murnaghan equation of state, the proposed strength criterion was used as the material model for RPC. The cavity expansion resistance was calculated numerically and analytically. It indicates that the numerical and analytical solutions are almost consistent under the same material response. Then, the strain softening behavior that cannot be resolved analytically was further introduced into the material model, and the numerical solution of the DCE model was obtained using LS-DYNA. To verify the present method, the 122.6 MPa RPC targets were tested using 14.5 mm diameter ogival nose projectiles at impact velocities of from 286 to 942 m/s. Combined with previous penetration model, the penetration depth of the present test was predicted. In addition, numerical simulation of this penetration test adopting the HJC model was also performed. It shows predictions of the present model are in good agreement with test and simulation results. Furthermore, the present model was used to predict the existing test date of RPCs with compressive strength of between 67.5 and 140 MPa, and the effectiveness of the present method was verified by comparing with predictions of previous empirical formulas.

Theoretical analysis for self-sharpening penetration of tungsten high-entropy alloy into steel target with elevated impact velocities

The “self-sharpening” effect has been observed experimentally in the penetration of tungsten high-entropy alloy (WHEA) into steel targets in previous study. From the microscopic observation of the residual WHEA long-rod projectile (LRP), the multiphase structure at micro-scale of WHEA is the key effects on self-sharpening penetration process. In order to describe the distinctive penetration behavior, the interaction between micro phases is introduced to modify the hydrodynamic penetration model. The yield strengths of WHEA phases are determined based on the solid solution strengthening methods. Combined with the elbow-streamline model, the self-sharpening mechanism is revealed in view of the multi-phase flow dynamics and the flow field in the deformation area of the LRP nose is characterized to depict the shear layer evolution and the shape of the LRP’s nose as well as the determination of the penetration channel. The self-sharpening coefficient considering the reduction of nose radius is proposed and introduced into the penetration model to calculate the depth of penetration and the penetration channel. Results show that the multi-phase interaction at the microscopic level contributes to the inhomogeneous distribution of the WHEA phases. The shear layer evolution separates part of the LRP material from the nose and makes the nose radius decrease more quickly. It is also the reason that WHEA LRPs have a pointed nose compared with the mushroom nose of WHA heavy alloy (WHA) LRPs. The calculated results agree well with the corresponding experimental data of WHA and WHEA LRPs penetrating into semi-infinite medium carbon steel targets with elevated impact velocities. The flow field in the projectile nose was established to describe the self-sharpening penetration process of the tungsten high-entropy alloy. Combined with the solid solution strengthening methods, the flow field of the projectile nose was structured based on the multi-phase flow. The nose radius before separation was set as $$r_\mathrm{b}$$ and after separation is $$r_\mathrm{a}$$ . The shear layer evolution separated part of the material from the nose and made the nose radius decrease more quickly.

Effects of spinning on residual velocity of ogive-nosed projectile undergoing ordnance velocity impact

In the present article, finite element analysis (FEA) based simulation on the study of the impact of projectiles having ogive nose shape has been made using ANSYS explicit dynamics. The effects of spinning on the residual velocity of ogive nosed projectile undergoing ordnance velocity impact have been presented. The variations of residual velocity due to different projectile materials and target plate thickness have been evaluated when the projectile is impacted by translational and spinning velocity. The target plates and ogive nosed projectile of a given material are discretized, and a rigorous error and convergence study has been made. Subsequently, the residual velocity of the considered model is evaluated by numerical techniques based on FEA. The results with the optimized meshed model are compared with the analytical results using the penetration theory and found that the results are well compared. Parametric study of the residual velocity has been made with varied ogive nosed materials and target plate thickness when the ogive nosed projectile undergoing ordnance velocity impact. Based on the numerical results, it has been found that the ogive nose projectile having tungsten alloy material is more effective undergoing ordnance velocity impact compared to steel 4340 material. For a given target plate thickness, spinning velocity, and impact velocity, the residual velocity is about 3 percent higher for the projectile made up of tungsten alloy compared to the steel 4340. The effects of the target plate thickness on the residual velocity of the ogive nose projectile do not seem to have much significant effects. It may be due to the simple reason that the ratio of the target plate thickness to projectile diameter is remaining within the intermediate range, i.e. within 1 and 10.

Energy dissipation characteristics of single curvature metallic shells subjected to ballistic impact

The impact resistance of single curvature semi-cylindrical shell targets of aluminum 1100-H12 was explored against hard steel cylindrical projectiles. Experimental as well as numerical investigations were carried out to observe the performance of shell targets against ogive, conical, blunt and hemispherical nosed projectiles. Effect of oblique impact was studied on the ballistic performance of the shell targets at 0 (normal), 15 and 30° obliquity. Further, the impact performance of 2 mm thick monolithic and in-contact layered targets of equivalent thickness was evaluated and compared. The projectiles were driven by a pneumatic air gun and the projectile flight path was captured with a high-speed camera. The experimental results obtained in terms of incidence and residual velocities, and deformation profile of the targets, were validated with the numerical analyses conducted in ABAQUS/Explicit solver. Johnson-Cook constitutive strength and damage material model was employed to simulate the deformation and damage evolution in the targets. The ballistic performance of both monolithic and layered targets impacted at oblique incidence, was compared in terms of ballistic limits, failure mechanisms, local and global plastic deformations and plastic strain energy absorbed in radial, circumferential, axial and shear deformation modes. The in-contact layered shell targets exhibited significantly higher impact resistance than the monolithic targets against all projectiles. Target configurations impacted at oblique incidence with conical and ogive nosed projectiles showed increase in global deformation, while, opposite behaviour was observed in case of blunt and hemispherical nosed projectiles. The plastic strain energy absorbed in various deformation modes correlated with the failure patterns observed in the target material during ballistic impact.

Load Characteristics in Taylor Impact Test on Projectiles with Various Nose Shapes

This study focused on the impact load produced by a projectile and its potential application in the Taylor impact test. Taylor impact tests were designed and carried out for projectiles with four types of nose shapes, and the impact deformation characteristics and variation of the impact load as a function of the nose shape and impact velocity were studied. The overall high g loading experienced by the projectile body during the impact was discussed, and based on classical Taylor impact theory, impact analysis models for the various nose-shape projectiles were established and the causes of the different impact load pulse shapes were analyzed. This study reveals that the nose shape has a significant effect on the impact load waveform and pulse duration characteristics, while the impact velocity primarily affects the peak value of the impact load. Thus, the loading of specific impact environments could be regulated by the projectile nose shape design and impact velocity control, and the impact load could be simulated. Research results support the assumption that the Taylor impact test can be applied to high g loading test.

Study on Model of Penetration into Thick Metallic Targets with Finite Planar Sizes by Long Rods

A finite cylindrical cavity expansion model for metallic thick targets with finite planar sizes, composed of ideal elastic-plastic materials, with penetration of high-speed long rod is presented by using the unified strength theory. Considering the lateral boundary and mass abrasion of the target, the penetration resistance and depth formulas are proposed, solutions of which are obtained by MATLAB program. Then, a series of different criteria-based analytical solutions are obtained and the ranges of penetration depth of targets with different ratios of target radius to projectile radius (rt/rd) are predicted. Meanwhile, the numerical simulation is performed using the ANSYS/LS-DYNA finite element code to investigate the variations in residual projectile velocity, length, and mass abrasion. It shows that various parameters have influences on the antipenetration performance of the target, such as the strength coefficient b, rt/rd, the shape of the projectile nose, and the impact velocity of the projectile, among which the penetration depth has increased by 18.95% as b = 1 decreases to b = 0 and has increased by 32.28% as rt/rd = 19.88 decreases to rt/rd = 4.9.

Cavitation phenomenon in penetration of rigid projectiles into elastic-plastic targets

This paper presents an analytical study on the cavitation phenomenon during penetration of a rigid projectile into an elastic-plastic target. The developed analytical approach is based on the general solution of the quasi-static and non-stationary dynamic cylindrical/spherical cavity expansion problem with assigned kinematic boundary condition at the cavity boundary (variable, time dependent radial velocity). An analytical projectile-target separation criterion is developed for a projectile having an arbitrary shape and for a target described by a simplified material model with a locked equation of state and a linear shear failure relationship. This relatively simple model may represent the behavior of different materials reasonably well yet allow an analytical solution of the problem. The paper derives the analytical expression of the contact zone size using both the cylindrical and spherical cavity expansion approaches and presents the related normal contact stresses acting on the projectile nose surface that maintains contact with the target. Examples of the developed formulation is presented for ogive nose and Rankine ovoid projectiles hitting aluminum targets, with a constant shear failure envelope, at different velocities and comparisons with known analytical and numerical solutions are shown. The effect of projectile and medium properties on the size of the contact zone are studied.

Effect of eccentricity and obliquity on the ballistic performance and energy dissipation of hemispherical shell subjected to ogive nosed

A numerical study was undertaken to investigate the effect of projectile eccentricity and obliquity impact on the ballistic performance of the Aluminium 1100-H12 1 mm thick hemispherical shell against ogive nose projectile. The projectile eccentric distance was taken with respect to the radius of the shell such as 0th, R/4th, 2R/4th and 3R/4th whereas, the incidence angle of the projectile as 0°, 15°, 30°, 45°, and 60° for each shell (68, 100, 150 and 200 mm diameter). The projectile was impacted at different velocities for each incidence angle and eccentric distance and ballistic limit obtained. Three-dimensional finite element simulations were carried out by using the Abaqus/explicit solver. Johnson cook material model was used to simulate the behaviour of a hemispherical shell. The results of the numerical study were elucidated through the experimental result conducted for normal impact. Moreover, user-defined coding written in python was used to obtain the energy dissipation in different stretching mode. The result showed that the ballistic performance of the target was influenced by both the eccentricity and obliquity. Also, the target was failed in ductile hole enlargement with petals formation however, the number of petals form was depended upon the eccentricity and obliquity.

Energy absorption characteristic of sandwich shell structure against conical and hemispherical nose projectile

Present study addresses the ballistic performance and energy absorption behaviour of the hemispherical sandwich shell structure having hexagonal honeycomb core against conical and hemispherical nosed projectile. The sandwich shell had two face sheet of radius 100 and 80 mm for outer and inner shells respectively, whereas for the honeycomb core cell thickness 0.05 mm, cell size 3.2 mm and core height 20 mm were considered. Al −1100 H12 was used for both the shell, whereas for the honeycomb core Al − 3003 H18 was employed. The projectiles of diameter 19 mm, length 50.8 mm and mass 52.5 g were hit on the crown of the sandwich shell. The experiments were performed using the pneumatic gun, whereas the ABAQUS/explicit solver was used for numerical simulations. The response of the sandwich shell was studied in terms of ballistic limit, residual velocity, failure modes and energy absorption by the sandwich structure. Numerical study further extended to perform parametric studies to investigate the effect of the face sheet thickness, core cell size and cell wall thickness on the response of the sandwich shell against conical and hemispherical projectile impact. The conical projectile required less energy for perforation as compared to the hemispherical nosed projectile.

Ballistic performance of monolithic and double layered thin-metallic hemispherical shells at normal and oblique impact

The present study discusses experimental and numerical investigations on the ballistic performance of aluminum 1100-H12 hemispherical shell targets of 150 mm diameter against 19 mm diameter cylindrical steel projectiles. The influence of nose profile of the projectiles on the impact resistance of the targets, was observed by varying the nose geometry to ogive, blunt, conical and hemispherical shapes. Effect of normal as well as oblique impact on the failure mechanisms and perforation process of shells was studied at 0 (normal), 15 and 30° angle from the normal incidence path. Further, the ballistic performance of two target configurations, viz. 2 mm thick monolithic and double layered in-contact shell targets was investigated and compared within the configurations. The finite element analysis of the ballistic impact on shell targets was done in ABAQUS/Explicit solver by employing the Johnson – Cook constitutive strength and damage model for deformable target material, whereas all the projectiles were assumed as rigid body. The ballistic performance of both shell target configurations against oblique impacts with different projectiles was evaluated and compared in terms of ballistic limit, local and global deformations, failure mechanisms and plastic work done in radial, polar, meridional and shear deformations. The obtained experimental results were then compared with numerical simulations and found in good corroboration. It was observed that both monolithic and layered shell targets showed highest ballistic resistance against hemispherical nosed projectile. For all the projectiles, layered shell targets displayed higher energy dissipation than monolithic targets.

Optimization and Numerical Analysis of the Ricochet of Conical Nose Projectile in the Collision with Ceramic-Aluminum Armor

The anti-armored bullets have more kinetic energy due to additional mass than ordinary bullets which increases their likelihood function of penetration for a different target. It is necessary to seek solutions to reduce the possibility of penetration of this type of bullets. One of the most important parameters influencing penetration is projectile impact velocity. The mechanism of penetration varies in different velocity ranges. In this paper, the phenomenon of buckling steel cone with a nose cone in a collision with ceramic targets was investigated by the explicit finite element method using LS-Dayna software. The numerical simulation shows acceptable accuracy after comparing the results with previous research. In this study, the critical angle of ricochet at a different velocity ranging from 700 m/s to 1000 m/s and optimization of the optimal thickness ratio of ceramic/metal targets has been considered. According to the simulation outputs and analytical relations, it is clear that the critical ricocheting angle has increased with increasing velocity and the probability of projectile penetration is higher. The results also show that in the case of an oblique collision at a certain angle, the projectile velocity decreases with increasing target thickness with no drastic changes in the directional angle. As the angle of oblique increases, the amount of penetration in the target decreases. For long rod projectiles, the reduction in kinetic energy at the same collision velocities is not much different for both vertical and oblique collision modes. The erosion of the projectile mass in oblique collisions is less than in vertical collisions at the same time.

An artificial intelligence model for ballistic performance of thin plates

This work presents the influence of ballistic testing variables on residual velocity of projectile and absorbed energy of aluminum 1100-H12 using design of experiments (DOE) and artificial neural network (ANN) approach. Simulations have been carried out with three process variables: Projectile nose shape, impact velocity and target thickness. Taguchi’s technique has been employed for experimental investigation. Trials were planned using an L 18 (61x33) orthogonal array with 18 combinations of testing variables was selected to assess the influence of various factors. Optimum testing variable combination was achieved by using analysis of signal to noise (S/N) ratio. Simulations were performed using Ansys Autodyn 3 D code. Simulated and experimental results were compared with each other and found well. The predictions of the ANN model, simulation results were in good agreement with the experimental data taken from literature.

Boundary Effect and Dynamic Response Study for the Penetration of Rigid Projectiles into Thick, Finite-Radius, Metallic Targets

This study uses the unified strength theory to analyse the elastoplastic stage and plastic stage of a linear strain-hardening target material while considering the effects of the intermediate principal stress and the free lateral boundaries of the target. In this investigation, analytical solutions of the radial stress in the cavity wall are obtained, and a unified penetration model of the target material is built. On this basis, penetration resistance formulas and penetration depth formulas for rigid projectiles with various nose shapes penetrating into thick, finite-radius, metallic targets are deduced, the solutions of which are obtained by utilizing the Simpson method. Accordingly, the proposed method offers a broader scope of application and higher accuracy than previous methods. Through this method, a series of analytical solutions based on different criteria can be obtained, and the penetration depth ranges of targets under different striking velocities can be effectively predicted. Moreover, penetration processes under different conditions are numerically simulated using the software ANSYS/LS-DYNA to study the motion law of the projectiles and the dynamic response of the targets. From the theoretical and numerical approaches, a list of influencing factors for terminal ballistic effects are analysed, including the strength criterion differences, the strength parameter b, the striking velocity v 0 , the projectile nose shape, and the target radius-to-projectile radius ratio rt/a. The results indicate that, as b changes from 1 to 0, the penetration depth Dmax increases by 22.45%. Additionally, Dmax increases by 40.76% when rt/a changes from 16 to 4; hence, it cannot be calculated as an unlimited-size target anymore when rt/a ≤ 16. In weapons field tests, the radius of the metallic target can be conservatively designed to be greater than 28 times the projectile radius to ignore the effect from the free lateral boundaries of the target.

Impact damage detection in CFRP and GFRP curved composite laminates subjected to low-velocity impacts

In this paper, the behavior of the CFRP and GFRP curved composite laminates under low-velocity impact loads is studied both numerically and experimentally. The time history of the mid-point deflection of the laminate along with the area of the damaged zone due to the impact are evaluated as two important indices of determining the behavior of the curved composite laminate under a low-velocity impact. In this regard, the active thermography damage identification technique and the image processing technology are employed to determine the pattern as well as the area of the damaged zone. In addition, the effect of the shape of the projectile nose on the behavior of the curved composite laminate is investigated by employing projectiles with flat, spherical, and conical noses with the same mass of 680 g.

Optimization and Numerical Analysis of the Ricochet of Conical Nose Projectile in the Collision with Ceramic-Aluminum Armor

The anti-armored bullets have more kinetic energy due to additional mass than ordinary bullets which increases their likelihood function of penetration for a different target. It is necessary to seek solutions to reduce the possibility of penetration of this type of bullets. One of the most important parameters influencing penetration is projectile impact velocity. The mechanism of penetration varies in different velocity ranges. In this paper, the phenomenon of buckling steel cone with a nose cone in a collision with ceramic targets was investigated by the explicit finite element method using LS-Dayna software. The numerical simulation shows acceptable accuracy after comparing the results with previous research. In this study, the critical angle of ricochet at a different velocity ranging from 700 m/s to 1000 m/s and optimization of the optimal thickness ratio of ceramic/metal targets has been considered. According to the simulation outputs and analytical relations, it is clear that the critical ricocheting angle has increased with increasing velocity and the probability of projectile penetration is higher. The results also show that in the case of an oblique collision at a certain angle, the projectile velocity decreases with increasing target thickness with no drastic changes in the directional angle. As the angle of oblique increases, the amount of penetration in the target decreases. For long rod projectiles, the reduction in kinetic energy at the same collision velocities is not much different for both vertical and oblique collision modes. The erosion of the projectile mass in oblique collisions is less than in vertical collisions at the same time.

Finite element analysis of projectile nose shapes in ballistic perforation of 2D plain woven Kevlar/epoxy composites using multi-scale modelling

The present research deals with the finite element analysis (FEA) considering high strength Kevlar/epoxy composites as a target plate subjected to ballistic impact by varying nose-shaped projectiles. A multi-scale modelling technique has been implemented with FEA to design the intricate weave architecture. The damage properties are adopted using a user-defined function in the explicit analysis. The proposed methodology is validated by the available literature. The conical-shaped projectiles will have more damage and penetration as compared to the flat projectiles, which are studied for two plate thickness. The conical 60° and conical 90° projectiles will have better penetration to the target plate even for the increased thickness, whereas the Conical 120° and Flat projectiles will have a significant reduction in residual velocities. Also, with the increment in thickness, the energy absorption will significantly increase for Flat projectiles as compared to the conical projectiles. For lower velocities, the yarn slippage and puncturing are the major factors of failure along with fiber breakage and matrix cracking. As the velocities increased, the dominant phenomena of failure will be the linear momentum transfer.

Similarities in the penetration depth of concrete impacted by rigid projectiles

Similarity can reflect common laws in the mechanism of rigid-body penetration. In this paper, the similarities in rigid-body penetration depth are demonstrated by three non-dimensional but physically meaningful quantities, i.e., $$ \rho_{\text{kinetic}} $$ , $$ I_{ \ln }^{*} $$ and $$ N^{\prime}_{1} $$ . These three quantities represent the non-dimensional areal density of projectile kinetic energy, the effect of nose geometry, and the friction at the interactive cross section between projectile and target respectively. It is shown that experimental data of rigid projectile penetration, from shallow to deep penetration, can be uniquely unified by these three similarity quantities and their relationships. Furthermore, for ogival nose projectiles, their penetration capacities are dominated by $$ \rho_{\text{kinetic}} $$ , which is consisted by non-dimensional effective length $$ L_{\text{eff}} $$ and non-dimensional quantity $$ D_{\text{n}}^{\text{p}} = \frac{{\rho_{\text{p}} v_{0}^{2} }}{AY} $$ which has the same form as Johnson’s damage number. On the sacrifice of minor theoretical accuracy, the non-dimensional penetration depth $$ P/d $$ can be understood as directly controlled by $$ D_{\text{n}}^{\text{p}} $$ , enhanced by projectile effective length $$ L_{\text{eff}} $$ under a multiplication relation, and optimized by projectile nose geometry in the formation of $$ I_{ \ln }^{*} $$ .

Experimental and Numerical Study of the Thermo-Viscoplastic Behavior of NICRO 12.1 for Perforation Tests

Dynamic impact tests using thin metal plates for ballistic characterization have received significant attention in recent years. The Johnson–Cook (J–C) model is extensively used in numerical modeling of impact and penetration in metals. The AISI (American Iron and Steel Institute) 301 steel family presents good impact behavior, excellent formability, and high corrosion resistance. Thus, NICRO (Nickel and Hard Chrome Plated Steel) 12.1 (part of the AISI 301 steel family) was chosen in this work, although parameters of the J–C model or impact results were not found in the literature. In this work, NICRO 12.1 steel plates, were characterized in ballistics with an initial impact velocity up to 200 m/s and three shape nose projectiles. The Johnson–Cook parameters for the NICRO 12.1 steel were calculated for a large range of temperatures and strain rates. Impact tests were carried out using three projectiles: conical, hemispherical, and blunt. The ballistic curves, failure mode, and maximum deformation obtained with each projectile, experimentally and numerically, were compared, and a good correlation was obtained.

Numerical and analytical simulation of ballistic projectile penetration due to high velocity impact on ceramic target

Simulation and analysis of the projectile impact and penetration problem and its effects are among the practical topics that can be used to design bulletproof panel and military equipment, construction of impact and penetration resistant structures, design of projectiles with appropriate penetration strength and High performance noted. One of the most important parameters affecting penetration is the impact velocity of the projectile. The mechanism of penetration varies in different speed ranges. In this paper, Ansys Autodyn software is used for intrusion simulation. The simulation carried out in this study is based on the accuracy and physical conditions of the problem and the compatibility of numerical simulation with the governing analytical relationships indicates the validity and accuracy of the assumptions made in the simulation. In this study, we selected materials such as material behavior, grating, contact surfaces, and controls, as well as collision of the blunt projectile with angles of 0º,15º,30º,45º by of high velocity impact 1000 m/s with the same mass and diameter and shape of the projectile nose and properties. Ceramic materials are discussed. The result of the numerical simulation comparison shows relatively good agreement between them.

Experimental and numerical investigations on the behavior of thin metallic plate targets subjected to ballistic impact

In this study, the description of energy absorption capacity in different deformation modes in the perforation of thin metallic aluminum 1100-H12 targets is presented. The targets were impacted with 19 mm diameter hard steel cylindrical projectiles of varying nose profiles, viz. ogive, blunt, conical and hemispherical shape. Effect of oblique impact on the perforation behavior of 255 mm diameter circular plate targets was studied at 0 (normal), 15 and 30° angles from the incidence line. The ballistic performance of two different configurations of plate targets, viz. monolithic target of 2 mm thickness and in-contact double layered target of equivalent thickness (2 × 1 mm) was also investigated and compared. The numerical simulations were executed using Johnson-Cook elasto-viscoplastic material model for the targets in ABAQUS/Explicit solver and the results were corroborated with the experimental observations. The ballistic performance of the targets against different nose shaped projectiles, was evaluated and compared in terms of ballistic limit velocities, local and global deformations in the target, failure mechanisms and plastic work done in various deformation modes involved in the impact process. It was observed that the ballistic limit for all targets was increased with obliquity, except for targets impacted with blunt nose projectile. The energy absorbed in different deformation modes corroborated with the failure mechanisms involved in the target during perforation. Both target configurations showed the highest ballistic resistance for hemispherical nosed projectile.