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Introduction/purpose: In recent times, with the tendency to develop new types of armor-piercing ammunition, constant investments in the development of new types of armored obstacles is necessary. Obstacles made of high-alloy steel plates are still the best form of protection against larger caliber ammunition. There are a number of factors to consider when selecting an alloy, including the weight, dimensions, intended use, desired ballistic performance, and costs. According to that, a numerical analysis of penetration of a 30mm armor-piercing fin-stabilized discarding sabot projectile into the steel alloy Weldox 460 plates of different thicknesses at a distance of 1000m with a velocity of 1300m/s is presented in this paper. Methods: The stresses and deformations of the penetration effect were calculated through numerical analysis and finite element modeling. To specify material characteristics, the Johnson-Cook material model and the fracture of materials model have been utilized. In order to define models and carry out numerical calculations, the software packages FEMAP and LS Dyna have been used in this paper. Results: For a numerical analysis of the penetration process of this projectile type against armor obstacle, four different armor plate thicknesses are calculated: 10mm, 50mm, 100mm, and 110mm. For each of them, the results are shown in a form of stress and displacement, so that the interaction phenomena between the sub-projectile and the armor plate can be described. Conclusion: Modeling the impact on armor-piercing obstacles is extremely difficult, time-consuming, and complex, and the resulting models very successfully (or with some deviation) approximate the real problem of projectile penetration. One of the most effective methods for solving problems of this kind and others of a similar nature in recent times is the finite element method analysis. The material and the target dimensions, as well as the ballistic parameters and the material of the projectile have the biggest influence on projectile penetration. The target's resistance to penetration increases when all input parameters are maintained at the same level and its thickness is increased, and vice versa. [ABSTRACT FROM AUTHOR]

Introduction/purpose: Thin plates made of high–strength steel are frequently used both in civil and military ballistic protection systems. In order to choose an appropriate type of alloy, it is necessary to fulfil a number of criteria, such as the condition of use, the desired ballistic performance, weight, dimensions, and price. This paper presents a numerical analysis of the penetration of a 30mm armor-piercing projectile with a velocity of 750m/s into steel alloy Weldox 460 plates of different thicknesses at a distance of 1000m . Methods: The analysis has been performed using numerical methods and finite element modeling to calculate stresses and deformation caused by the penetration effect. For defining material characteristics, the Johnson- Cook material model and the fracture of materials model have been used. In this paper, the software packages FEMAP and LS Dyna have been used for defining models and performing numerical calculations. Results: The results of the performed numerical analysis as well as the obtained stress and displacement values are presented for four different armor plate thicknesses: 30mm, 33mm, 34mm, and 40mm. The results show a penetration effect and an interaction between the projectile and the armor plate. Conclusion: Modeling the impact on armor-piercing obstacles is very complex, extensive, and demanding, and the formed models approximate the real problem of projectile penetration in a very successful way (or with a certain deviation). In recent times, the analysis using the finite element method has proven to be one of effective approaches to solving such and similar problems. The material and the dimensions of the obstacle, as well as the material and the ballistic parameters of the projectile have the greatest influence on projectile penetration. Keeping all the input parameters at the same level and increasing the thickness of the target leads to its increased resistance to penetration. [ABSTRACT FROM AUTHOR]

Biological structures possess excellent damage tolerance, which makes them attractive for ballistic protection applications. This paper develops a finite element modelling framework to investigate the performance of several biological structures that are most relevant for ballistic protection, including nacre, conch, fish scales, and crustacean exoskeleton. Finite element simulations were conducted to determine the geometric parameters of the bio-inspired structures that can survive projectile impact. The performances of the bio-inspired panels were benchmarked against a monolithic panel with the same 4.5 mm overall thickness and projectile impact condition. It was found that the biomimetic panels that were considered possessed better multi-hit resistant capabilities compared to the selected monolithic panel. Certain configurations arrested a fragment simulating projectile with an initial impact velocity of 500 m/s, which was similar to the performance of the monolithic panel. [ABSTRACT FROM AUTHOR]

Introduction/purpose: The paper presents a numerical simulation of an impact of a 12.7 mm projectile on an armored metal plate with a velocity of 500 m/s at a distance of 900 m. Numerical simulations offer the possibility of drastically reducing the time required to obtain results in comparison to the time required for planning, organization and execution of experiments. The numerical simulation is done by variations in the thickness of the armor metal plate, specifically an armor metal plate of a thickness of 10 mm, 17 mm, 18 mm, and 23 mm. The mentioned armored plate thicknesses were chosen based on the results in order to determine the limit thickness of the armored plate for the projectile perforation limit, as well as for complete ballistic protection. Methods: Finite element modeling is used for analyzing stresses and deformations of the armored plates. The mentioned method calculates the impact of the projectile on the obstacle, precisely the collision of the projectile and the armor plate. Results: For the comparative analysis, the parameters used are the values of the stress and the displacement. For each of the above-mentioned thicknesses of the armored metal plate, the values of stress and displacement during projectile impact were determined. The results of this study show how the thickness of the armor plate affects the interaction of the projectile and the armor plate. Conclusion: If the physical and chemical characteristics of the armored plate remain unchanged, as the thickness of the armored plate increases, the possibility of projectile penetration decreases, and vice versa. This research is of essential importance because it analyzes the stresses and deformation of armor plates whose basic role is the protection of personnel and equipment from the projectile impact. In this regard, the thickness of the armored plate for semi-penetration of the projectile is determined. [ABSTRACT FROM AUTHOR]

With the development of weapons, monolithic armor is hard to resist these threats. Therefore, a SiC/TC4/UHMWPE laminates multi-layered composite armor against 7.62 mm armor piercing projectile is proposed in this paper. To investigate the ballistic performance of the SiC/TC4/UHMWPE laminates composite structure, a finite element model (FEM) is created in LS-DYNA. Verification FEMs are carried out on the materials of the silicon carbide (SiC) material, Ti–6Al–4V (TC4) material and ultra-high molecular weight polyethylene (UHMWPE) fiber to verify the accuracy of these materials. Furthermore, it is shown that establishing FEM of SiC/TC4/UHMWPE laminates structures can be reasonably implemented. Based on simulation results, SiC/TC4/UHMWPE laminates composite structure has a better ballistic performance than other systems using only two of the above materials. In addition, results also reveal that the SiC plate is suitable for face-sheet to wear the weight and kinetic energy of the projectile, while TC4 plate can enhance the penetration resistance of SiC plate and UHMWPE laminates backplane can maintain the integrity of the composite structure to resist higher initial velocity impact, thus providing an innovative way to improve the ballistic performance under the high-velocity impacts. [ABSTRACT FROM AUTHOR]

• The protection capability of modified aramid fabrics against fragment simulating projectiles and full metal jacketed bullets. • The design of layers considering both critical velocity and back face deformation. • The priority of intercepting bullets and reducing blunt trauma. Soft body armor is required to meet threats of both bullets and explosion fragments in battlefield. However, designing body armor that can protect against these two types of projectiles considering both critical velocity and back face deformation (BFD) is often based on experience and extensive ballistic experiments. This paper proposes a quick design model for determining the layers of aramid fabrics modified by polyethylene (PE) to protect against fragment simulating projectiles (FSP) and full metal jacketed bullets (FMJ). Firstly, ballistic experiments are conducted discovering the optimal concentration of PE modification against the sphere and FSP is 10 %. Secondly, finite element model is adapted to explore the protection capabilities of modified aramid fabrics against FSP and FMJ and a linear relationship between the BFD and the critical velocity has been observed. Thirdly, an analytical model is established to uncover the reason of this relationship. Finally, a design model is proposed to configure the improved outer tactical vest (IOTV) generation III based on the derived formulae of critical velocity and BFD for different layers of modified aramid fabrics against FSP and FMJ. The model indicates that the objectives of intercepting FSP or FMJ and reducing blunt trauma are usually not simultaneously attainable. 38 layers of modified aramid fabrics are sufficient to meet the protection requirements for both FSP and FMJ, regardless of critical velocity and BFD. Besides, 498 m/s is the threshold of FMJ impact velocity to determine the priority of intercepting bullets or reducing blunt trauma. The design model can serve for the development of lightweight and effective body armor. [ABSTRACT FROM AUTHOR]

• Four surface wave profiles were investigated for hypervelocity impact shielding. • Wave profiles caused novel projectile fragmentation and debris cloud shape. • Wavy plates outperform flat plate in terms of energy dissipation. • Simple design variations allow wavy plates to perform considerably better. Continuously increasing micro meteorite and orbital debris (MMOD) in space poses a threat to any manned or unmanned space vehicle with increasing probability of damaging object impact. To address the sufficient level of protection of space vessels, many Whipple shield configurations has been studied for over half a century. Bumper plate of Whipple shields studied in existing literature are flat surfaced plates. In contrast to earlier studies, this paper investigates the reaction of bumper plates with wavy surfaces against hypervelocity impact by analysing how they contribute to projectile fragmentation, formation of debris cloud, and how they dissipate the impact energy. Aluminium plates with four different surface wave profiles (WPs) were numerically investigated under hypervelocity impact conditions to assess their performance on disintegration of the impacting projectile. Fragmentation patterns of spherical aluminium projectile and debris cloud generated by projectile-wavy plate couples were examined and compared with the equivalents observed in flat-surfaced plate impact. A hybrid Smoothed Particle Hydrodynamics (SPH) combined with finite element modelling (FEM) approach was adopted using ANSYS software to simulate hypervelocity impact phenomenon at 3 km/s. Results of the numerical work carried out in this study revealed the distinctive debris cloud generation that has never been reported before in the existing literature. Furthermore, compared to the flat plate, wavy plates are found to be more effective in decreasing the impact energy. [ABSTRACT FROM AUTHOR]

This paper explores the transient mechanics mechanism of the projectile with double rotating bands engraving into the rifle and the propellant gas pressure distribution law during the rotating band engraving process. Previous studies usually ignored the coupling of projectile, artillery, and gunpowder parameters during the engraving process. To end this, taking a large-caliber artillery system as the research object, a projectile-barrel-charge coupled finite element model is established based on the two-phase flow interior ballistic theory and the finite element method, followed by numerical simulation. Through the comparison with experimental results, such a modeling method is proved to be effective. [ABSTRACT FROM AUTHOR]

This paper discusses the design, fabrication, and analysis of a coil assembly for a multistage induction-type coilgun system with the pulsed power module. The voltage, current, force, velocity, acceleration, and efficiency of the coilgun system were analyzed using the finite-element method. Based on the results of the electromagnetic analysis, the geometry of the coil assembly part for coilgun system was defined. The designed coilgun system has been found to exhibit high energy efficiency and safety against the force and temperature of the coil assembly. The designed coil assembly part was fabricated and analyzed. The design specifications and analysis results concerning the coilgun can, hence, be effectively utilized to develop a large-scale multistage induction-type coilgun system. [ABSTRACT FROM AUTHOR]

The present paper aims to assess the risk of rib fractures caused by any rigid less-lethal kinetic energy projectiles. To that end, a coupled experimental and numerical approach is proposed to relate ballistic experiments with the risk of blunt trauma. A polymer gel block is employed as ballistic testing medium to interpret ballistic impacts through the measurement of the dynamic gel wall displacement. Moreover, a biofidelic 50th percentile human torso finite element model created in the code Hypermesh (Altair HyperWorks ©) is used to replicate experiments and real world accidents. Then, the probability curve of rib fractures is a function of the viscous criterion and derives from a study on human cadaver mid-sternum available in the literature. Twelve impact conditions of rigid projectiles are applied to a SEBS gel block and are replicated on the human torso model mid-sternum. A statistical analysis is performed by virtue of a Spearman's correlation matrix in order to identify relations between experimental measurements and the viscous criterion evaluated numerically. The determination of both statistical significances and correlation coefficients results in several strong correlations between experimental measurements and the viscous criterion evaluated numerically. These relations imply the establishment of transfer functions between experimental metrics on the gel block (the maximum gel wall displacement and a gel wall displacement - rate of displacement based metric) and the probability of rib fractures. Finally, these correlations constitute a primary and an up-and-coming predicting tool for the risk of rib fractures. [ABSTRACT FROM AUTHOR]

Highlights • A series of rigid projectile penetration tests on concrete targets pre-damaged by explosively formed projectile (EFP) is conducted. • Impact performance of the individual rigid projectile and two-stage munitions, as well as the influences of concrete type, projectile striking velocity and target configuration are experimentally studied. • Penetration process of the following rigid projectile into the pre-damaged target is numerically reproduced with the restart input data method implemented in the finite element program LS-DYNA. • Influences of the liner material and configuration of shaped charge, as well as the rigid projectile diameter on the impact performance of two-stage munitions are further discussed. Abstract The two-stage munitions is newly utilized to attack the hard and deeply buried protective structures, while the related work on the impact performance of two-stage munitions into concrete targets is still limited. This paper addresses the impact performance of one typical two-stage munitions, which consists of a precursor explosively formed projectile (EFP) and a following rigid projectile. Firstly, based on our previous EFP impacting test on the concrete targets (Hu et al., IJIE, 2017), a series of rigid projectile penetration tests on these pre-damaged concrete targets is further conducted. By assessing the dimensions of the penetration boreholes, the influences of concrete type (normal strength concrete (NSC) and reactive powder concrete (RPC)), target configuration (monolithic and spaced) and rigid projectile striking velocity (300 m/s–500 m/s) on the targets damage subjected to the two-stage munitions are experimentally discussed. Then, by adopting the restart input data method implemented in the finite element (FE) program LS-DYNA, the targets damage subjected to the precursor EFP is recorded and the penetration process of the following rigid projectiles into the pre-damaged targets is numerically reproduced. Finally, based on the validated restart input data method, material models and the corresponding parameters, the impact performance of the two-stage munitions with different liner materials (T2 copper and 2A12 aluminum) and configurations (spherical segment, conic and truncated) of shaped charge as well as the following rigid projectile diameters (0.1∼0.9 times the shaped charge diameter) is further discussed, respectively. [ABSTRACT FROM AUTHOR]

Highlights • An existing Reissner Mindlin shell element is enriched using X-FEM to model dynamic crack propagation in thick shells. • A diagonal mass matrix is used for the enriched displacement and rotational DOFs. • An explicit representation of the crack lying on the shell?s mid-surface is done using a 1D mesh. • A crack propagation criterion able to account for tensile and shear driven fracture is used. Abstract This paper is devoted to the modeling of crack propagation under impact loadings in thick shells composed of metallic materials using X-FEM. The proposed thick shell element is based on the existing Q 4 γ 24 4-node shell element for fast transient loadings that is enriched in the present work using X-FEM. The shell is considered to be always cut by a through the thickness crack. This element is hence enriched only with jump Heaviside functions on all degrees of freedom (displacements as well as rotations). The mass matrix corresponding to all added DOF is simply a copy of the usual continuous DOF diagonal mass matrix. The crack is discretized explicitly with a simple 1D mesh that lives on the shell's mid-surface and independently of the finite element mesh. Plasticity as well as stress field used for crack propagation criterion is evaluated using 5 Simpson points across the thickness. The crack propagation criterion is based on the measure of an equivalent stress at the crack tip and can predict both tensile and shear driven fracture as well as transitions between those two regimes. Comparisons with elastoplastic crack propagation experiments involving fracture under transient loadings show that the method is able to reproduce experimental fracture quite well. [ABSTRACT FROM AUTHOR]

Highlights • Explicit FE analysis of ballistic impact on reinforced concrete panels. • RHT model is able to predict velocity and chip size for all type of projectiles. • Kinetic energies were mostly absorbed by the concrete panel. • None of the projectiles produced serious damages to the concrete panels. Abstract The resistance of concrete barriers to high velocity projectile impact from firearms is a research topic that has been of interest for quite some time, with the first known study going back to the mid-18th century. Despite this long history, only a very limited number of the test results are available in the public domain due to their sensitive nature and strategic importance. This situation has made the development of precise models for predicting the effects of ballistic impact difficult, despite the recent availability of highly refined and powerful calculation tools. Many researchers are still convinced that a validated methodology does not currently exist for this type of problem due to the number of uncertainties. Within this context, the objective of the present work is to study projectile impact on barriers made of reinforced concrete with explicit Finite Element (FE) simulations. In particular, this paper presents a FE analysis that considers the full range of projectile class as defined in the ballistic standards. Results from simulation are also compared with experiments. [ABSTRACT FROM AUTHOR]

In this paper, dynamic analysis of two different weapon systems (35 mm Anti-Aircraft Barrel (AAB) and 120 mm Grooved Tank Barrel (GTB)) under the effect of statically unbalanced projectile has been performed with a new 12 DOF 3-D element technique using Finite Element Method (FEM). The muzzle deviations, which negatively affect the barrel shooting accuracy at firing, are calculated in a time dependent manner using Newmark β algorithm with high accuracy at both axes (y and z) considering the Coriolis centripedal and centrifugal forces. The effect of such fundamental physical parameters as shift from rotating center and angular velocity belonging to the unbalanced projectile on barrel dynamics are analyzed with this new and affective FEM. As a result, it was found out that 1% of a millimeter shift from projectile belonging to a weapon system leads to excessive vibration on both axes and compromises the shooting accuracy of the barrel. [ABSTRACT FROM AUTHOR]

This paper deals with shielding resonator structures for possible application in electromagnetic rail launchers. The main aspects of the resonant shield are revisited via the spatial averaging concept of macroscopic quantities and of the effective magnetic behavior. In particular, it is recalled how for a resonator structure it is possible to get negative values of the effective permeability and it is shown how this can be exploited for shielding applications. Simulation results are obtained via a commercial finite-element code through a 3-D frequency analysis. The shielding effectiveness is estimated at different operating conditions by varying the resonance frequencies of the shield, while maintaining the constant field operating frequency. Possible advantages and critical aspects of such an approach are discussed throughout this paper, and an estimation of the thrust force acting on the projectile is also provided. [ABSTRACT FROM PUBLISHER]

Multipole field reconnection electromagnetic launchers are highly efficient electromagnetic transmitters, which can solve the inherent flaws in conventional electromagnetic launchers such as the small axial thrust and the sliding contact. In addition, there are many tunable parameters for this launch mode. In order to improve the acceleration performance, the axial acceleration force, the efficiency of the system and influence of capacitor parameters on the emission performance is focused in this paper. Some theories about this launch mode is introduced. A finite-element model of the system was constructed and the commercial finite-element software Ansys Maxwell was applied. The simulation results indicate that increasing the voltage and capacitance of the capacitor can improve the axial acceleration force of the projectile, but the efficiency of the system may not be enhanced. We proposed that it should be appropriate to reduce the capacitance, while increasing the charging voltage value at high-speed launch. [ABSTRACT FROM AUTHOR]

This paper addresses the impact performance of explosively formed projectile (EFP) formed by shaped charge (SC) on the concrete targets. Firstly, a series of EFP penetration/perforation test on concrete targets are conducted. By assessing the dimensions of front spalling and rear scabbing craters as well as the penetration borehole, the influences of SC liner material, concrete type and target configuration (monolithic and spaced) on the target damage are experimentally discussed. Secondly, by utilizing the multi-material Arbitrary Lagrange-Euler (ALE) algorithm, Fluid-Structure Interaction (FSI) method and erosion algorithm implemented in the finite element (FE) code LS-DYNA, and describing the concrete targets with the original and modified HJC models, the formation and impact processes of EFP are well reproduced. Furthermore, based on the validated constitutive models and the corresponding parameters, the influences of explosive type, liner configuration and thickness, first concrete panel and air interlayer thicknesses of spaced target on the impact performance of EFP are further discussed. The derived conclusions could provide helpful references for the analysis and design of the concrete protective structures, and the evaluation of the ballistic performance of EFP. [ABSTRACT FROM AUTHOR]

Induction coil launcher (ICL) is an electromagnetic accelerator that uses Lorentz force to accelerate a projectile with a conducting armature. In this paper, the effects of the height and starting position of the armature on the performance of the ICL were analyzed. Launching experiments were conducted to verify the analysis results. The speed of the projectile converged to a saturated value as the armature height increased. We found that there exists an optimal starting position of the armature for the highest speed. The concept of inductance gradient was adopted to explain the analysis results. It was possible to predict the acceleration characteristics and to estimate the optimal starting position using this concept. Results show that the armature height should be longer than the drive coil height ( \textH\mathrm {coil}) , and the bottom of the armature should be positioned between (1/4)H\mathrm {coil} and (1/2)H\mathrm {coil} at the start to obtain the highest speed. The experimental results showed good agreement with the simulation analysis results. [ABSTRACT FROM AUTHOR]

Abstract: The paper describes a numerical study on the perforation of sheet steel by a projectile under high impact velocity to predict the ballistic behaviour and, in particular the ballistic limit. The parametric study is performed for several of the important variables in the numerical model using Abaqus/Explicit finite element code and their effects are reported in the paper. The variables considered include the target configuration (thickness), constitutive material model of the target, mass of the projectile, friction between the projectile and the target and shape of the projectile. The effect of the material behaviour was also studied through the use of two constitutive relations and to conclude the ballistic curves were calculated for several different target materials using data from literature. The numerical results were compared with existing data sourced from the literature and an analytical model was used to compare the trend obtained using numerical simulations in terms of ballistic limit. [Copyright &y& Elsevier]

This paper presents the results of an investigation of the ballistic limits and failure modes of AA2024-T351 sheets impacted by cubical projectiles. The effect of cube orientation on the ballistic limit and failure modes was considered in detail. Three impact configurations were investigated. Configuration one, two and three considered face, edge or corner impacts correspondingly. The experimental results were complemented with finite element analysis results in order to explain the observations. The lowest ballistic limit (202 m/s) was observed when the cube edge impacted on the target. In the cube face impacts, the ballistic limit was higher (223 m/s), and the highest ballistic limit (254 m/s) was observed for the corner impact. Although the face impact did not have the lowest ballistic limit, this impact configuration resulted in the least amount of projectile energy loss for impacts above the ballistic limit. With the aid of finite element modelling, it was possible to develop a better understanding of the test results and explain that the observed differences in impact response were not just due to a difference in projectile frontal area, but also due to the combination of the localised deformation near the projectile impact point and the resulting global (dishing) deformation. [ABSTRACT FROM AUTHOR]

In this paper, a modified laminated finite-element model based on subcell of unit cell and CDM material model was developed in nonlinear explicit finite-element code to investigate the dynamic response of 2D triaxial braided composite under ballistic impact of projectile. Six subcells, which were considered as laminate with different stacking sequences using solid elements, were employed to represent one unit cell of triaxial braided composites, therefore, the fiber-laying direction of braiding architecture is reproduced. In the prediction of the subcell model, an approximate round conical deformation area forms in the target and the failure modes are mainly longitudinal and transverse cracking due to tension. Compared with the continuum model, the subcell model is capable of analyzing the energy absorption of fiber in each direction. Although the failure modes are similar for both methods, the subcell model is more effective in prediction of impact wave propagation than the continuum model because it describes the fiber arrangement of triaxial braided composites. The developed subcell model will be an effective tool for the design process of carbon/epoxy composite fan casings. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a ballistic impact simulation of an armour-piercing projectile in hybrid ceramic/fiber reinforced composite armour. The armour is composed by an alumina plate and an ultra high molecular weight polyethylene composite. In order to model the armour behavior three different constitutive models were formulated and implemented into ABAQUS/Explicit finite element code. Comparisons between numerical predictions and experimental results in terms of damage shape/extent and V50 are also presented and discussed in the paper. [Copyright &y& Elsevier]

This paper focused on the verification of the current filament method and the performance comparison of different armatures. Armature has as much influence on the performance of a coil launcher as any other major subsystem. The design of an armature is influenced by a large set of highly coupled parameters. The sleeve armature is a common choice for experiment and analysis of a coil launcher. The current filament method is widely used to analyze the sleeve armature. However, due to skin effect, the current distribution will be inconsistent, and excessive heating will be caused in the sleeve armature. How to use the current filament method accurately should be considered. Another good choice is the solenoid armature, which can make current and temperature distribution uniformly. To verify the current filament method and compare the performance between a sleeve armature and a solenoid armature, several kinds of projectiles were constructed and tested, including a sleeve projectile, a 24-turn copper-ring projectile, a 20-turn wire-ring projectile, and a 20-turn solenoid projectile. Then, 2-D finite-element simulations based on the experiments were taken to further study the problems. It is shown that in the sleeve armature (including multiturn ring armature) most of the induced current tend to distribute unevenly in the armature. Over concentration of the current will cause excessive heat and limit the material, structure, velocity, and efficiency of the sleeve armature. The sleeve armature must be divided into enough number of filaments; otherwise, the current filament method may be invalid. A solenoid armature can solve these problems by distributing the induced current evenly. However, fabrication of the solenoid armature becomes another difficulty. Further analysis of the current density in the solenoid armature shows that the skin effect will work in the wire of the solenoid, but it has little influence on the system performance. A detailed description of the experiments and simulations will be presented in this paper. [ABSTRACT FROM AUTHOR]

The ballistic perforation test results of 4-step 3-dimensional (3D) braided Twaron®/epoxy composites, which were subjected to impact by conically cylindrical steel projectile, are presented. The residual velocities of projectile perforated composites target at various strike velocities were measured and also compared with that from finite element calculation. ‘Fiber inclination model’ for 3D textile composites was adopted to decompose the 3D braided composite at quasi-microstructure level for the geometrical modeling in preprocessor of FEM. The material modeling was also based on this simplified model. The finite element code of Ls-Dyna was used to simulate the impact interaction between projectile and inclined lamina. The residual velocity of projectile perforating the entire 3D braided composite can be calculated from the sum of kinetic energy loss of the projectile that obtained from FEM. From the simulation of ballistic penetration process and comparison between numerical results and experimental results, it proves that the analysis scheme of quasi-microstructure level in this paper is valid and reasonable. The simplified method in this paper could be extended to model other kinds of 3D textile composites under ballistic impact. [Copyright &y& Elsevier]

This paper presents the computational-based ballistic limit of laminated metal panels comprised of high strength steel and aluminium alloy Al7075-T6 plate at different thickness combinations to necessitate the weight reduction of existing armour steel plate. The numerical models of monolithic configuration, double-layered configuration and triple-layered configuration were developed using a commercial explicit finite element code and were impacted by 7.62 mm armour piercing projectile at velocity range of 900 to 950 m/s. The ballistic performance of each configuration plate in terms of ballistic limit velocity, penetration process and permanent deformation was quantified and considered. It was found that the monolithic panel of high-strength steel has the best ballistic performance among all panels, yet it has not caused any weight reduction in existing armour plate. As the weight reduction was increased from 20-30%, the double-layered configuration panels became less resistance to ballistic impact where only at 20% and 23.2% of weight reduction panel could stop the 950m/s projectile. The triple-layered configuration panels with similar areal density performed much better where all panels subjected to 20-30% weight reductions successfully stopped the 950 m/s projectile. Thus, triple-layered configurations are interesting option in designing a protective structure without sacrificing the performance in achieving weight reduction. [ABSTRACT FROM AUTHOR]

This paper presents an innovative approach for 3D Lagrangian finite element modelling of the fragmentation of a blunt shaped projectile (BSP) made of a tungsten heavy alloy impacting against a ceramic Alumina tile. The aim of this work is to develop an alternative way of modelling the fragmentation of both the projectile and the ceramic tile, with respect to the classical approach of the deletion of the finite elements. In particular, the projectile is made of an assembly of pre-fragmented sub-parts, without the possibility of deletion of the finite elements, with a cohesive law that allows the separation of the sub-parts when the suitable failure criterion is met. The ceramic tile model adopts the transformation of the finite elements into SPH (smooth particle hydrodynamics) elements when the failure criterion is met. Both these approaches are adopted to conserve the mass and to avoid discontinuities of the contacts between the parts. The heat generation by plastic work and the rate dependent properties of the materials are reproduced in the analyses. The model is compared with experimental data from the literature, in particular validating its performance in predicting the residual velocity and the residual mass of the projectile; an analysis of the wave propagation and damage morphology has also been carried out. [ABSTRACT FROM AUTHOR]

• A simple numerical framework is established based on a semi-empirical model. • Dynamic behaviors of rigid projectiles impacting concrete targets are predicted. • Effects of crater formation and the presence of a free surface are considered. • The influences of projectile geometries and impact conditions are investigated. • The critical angle and velocity that enable projectile ricochet are identified. This paper presents a simple and efficient semi-empirical model for predicting the dynamic behaviors of rigid ogive-nosed projectiles after obliquely impacting semi-infinite concrete targets. We consider the normal stress acting on the projectile surface as a result of the target resistance. We also reflect the decrease in normal stress caused by crater formation and the presence of the free surface on the target. The normal stress is formulated as a function of the projectile geometry and the properties of the target material. To verify the proposed semi-empirical model, we establish computational frameworks combining the finite element method and smoothed particle hydrodynamics. These frameworks are confirmed to provide results consistent with the experimental data for the normal impact of projectiles on concrete targets. By comparing the results obtained from the semi-empirical model with the reference results obtained from the computational frameworks, we demonstrate that the semi-empirical model can successfully predict the penetration or ricochet of projectiles following oblique impact. Furthermore, considering the nose sharpness, slenderness, impact velocity, and oblique incidence angle of the projectiles as key parameters, we investigate their effects on the dynamic behaviors of projectiles. The penetration capabilities of projectiles increase with sharper and slenderer geometry, higher impact velocity, and lower incidence angle. In particular, considering various combinations of these parameters, we identify the critical conditions for the incidence angle and impact velocity that lead to the ricochets of projectiles. The minimum incidence angle, at which ricochets occur, increases in proportion to the nose sharpness, slenderness, and impact velocity. The maximum impact velocity, up to which ricochets occur, decreases as the nose sharpness and slenderness increase and the incidence angle decreases. [ABSTRACT FROM AUTHOR]

The dynamic behavior of the railgun housing including the rails is of great importance for the system performance. The transient loading (magnetic pressure) may have a negative influence on the sliding electrical contact required for this acceleration technology. Therefore, the analysis of the displacement of the inner rail surfaces due to elastic waves is of great importance. The French-German Research Institute of Saint Louis (ISL) is operating several railguns with housings characterized by an open barrel design allowing for innovative diagnostic techniques. The repelling forces between the rails are countered using discrete steel bolts. The rails are mounted to bars made from composite material. In the past, we presented the experimental and numerical findings concerning the dynamic behavior of such railguns in single shot mode. In this paper, we present for the first time 3-D finite element calculations concerning the dynamical behavior of the ISL RApid FIre RAilgun operating in multishot mode. Multishot scenarios with fire rates of 50 Hz are considered and particular attention is paid to the question if the dynamical behavior of the railgun is influenced by preceding shots. [ABSTRACT FROM PUBLISHER]

This paper describes the process of creating a numerical FEM (finite element method) model of the 5.56 × 45 mm SS109 projectile. The model was used to calculate the temperatures occurring in the projectile materials during the impact on the steel plate at an angle of 45°. The purpose of the investigation is to estimate the ability of a ricocheting projectile to cause ignition. For the same projectile, experimental tests were also carried out under the conditions adopted for the numerical investigation in order to validate the FEM model. During the experiment, temperature was measured with a thermal camera; the phenomenon was also recorded with a colour high-speed camera. [ABSTRACT FROM AUTHOR]

Abstract: This paper presented a three-dimensional (3D) finite element analysis approach to study the projectile penetration into rock-rubble overlays considering the randomness of rock-rubble in shape and distribution. The generation algorithm of 3D rock-rubble with random size and shape was firstly proposed. The dropping and compacting algorithms for the random distribution of all particles of rock-rubble in an overlay were then developed. Thirdly, a finite element grid was formed using the mapping algorithm. An analysis approach for the 3D finite element model of the random distribution of all particles of rock-rubble in an overlay was established by employing the hydrocode LS-DYNA taking into account the different materials properties and contact effect. In order to validate the analysis approach, the numerical results were compared with the limited test data, and a good agreement was obtained. Finally, numerical studies of the projectile penetration into the grouted concrete rock-rubble overlays were presented under different impact conditions, focusing on the penetration depth, yawing angle, trajectory and projectile deformation. It is indicated that impact obliquity affects the penetration depth, terminal yawing angle and penetrator deformation greatly. In order to reveal the stopping and deflecting mechanism of rock-rubble overlays, parametric studies were carried out to analyze the effects of different impact conditions and target configurations on projectile penetration. The numerical results show that the size, strength and volume percentage of rock-rubble and grouted concrete strength are critical to penetration depth and terminal yawing angle. [Copyright &y& Elsevier]

Along with the continuous development of the intellectualized antitank ammunition and the application of the future electric gun in the battlefield, the armored vehicles encounter an increasingly heavy threat in the battlefield. So the armor protection has to develop new technologies so as to enhance the armored vehicles' survivability in the battlefield. A new concept practical application of the pulsed power technology-active electromagnetic (EM) armor was discussed in this paper. It combined the intellectual file-control, advanced detector, and precise EM projectile interceptor. It must be the developing direction of the active protection system. A structural and mathematical model of the active EM armor projectile interceptor based on the principle of single stage coil launcher is given in this paper. It analyzes the effects of the electric parameter in the discharge circuits and the structural property of the interceptor to the launching velocity and efficiency of the interceptor. Finally the model is simulated numerically by finite-element analyses. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents experimental and numerical investigations on ballistic impact behaviors of GLARE 5 fiber-metal laminated (FML) beams of various thicknesses. A high-speed camera was used to measure impact and residual/rebound velocities and also to assess damage evolution in the FMLs. The incident projectile impact velocity versus the residual velocity (VI –VR ) was plotted and numerically fitted according to the classical Lambert–Jonas equation for the determination of ballistic limit velocity, V 50. The results showed that the V 50 varied in a parabolic trend with respect to the metal volume fraction (MVF) and specimen thickness. The interfacial debonding as well as bending and stretching in aluminum layers played the significant roles in dissipating the impact energy in the GLARE 5 FML beams. The 3D finite element (FE) code, LS-DYNA, was used to model and validate the experimentally obtained results. Good agreement between experimental and numerical results was achieved. It was found that for a given specimen configuration, by increasing the projectile incident velocity up to its V 50, the maximum contact force increased. By further increasing the projectile velocity above its V 50, the maximum contact force was relatively invariant with respect to an increase in the projectile incident velocity. [Copyright &y& Elsevier]

Abstract: In this paper, based on LS-Dyna code, a new finite element (FE) simulation of the ballistic perforation of the ceramic/composite targets, which impacted by cylindrical tungsten projectiles, has been presented. Research on this method has been conducted by a few research groups in recent years. The ceramic material, which is the front plate, has been made of Alumina 99.5% and composite back-up plate composed of Twaron fibers. The 2-dimensional (2D), axi-symmetric, dynamic-explicit, Lagrangian model has been considered in this simulation. The Johnson–Cook, Johnson–Holmquist and Composite-Damage materials behaviors have been used for projectile, ceramic and composite materials respectively. The brittle fracture and fragmentation of ceramic conoid, the failure criteria based on fracture of fibers or matrixes of composite materials and erosion or flattening of projectile during perforation have been considered. The residual velocity and perforation time has been obtained and compared with the available analytical models. The results show that when the ceramic is impacted by a projectile, a fragmented ceramic conoid breaks from ceramic tile and the semi-angle of ceramic conoid with increasing initial velocity decreases. Furthermore, the dishing of composite layers at high impact velocities and the delamination of layers near the ballistic limit velocity decrease. [Copyright &y& Elsevier]

The dynamic behavior of the rail-gun housing, which includes the rails, is of great importance for the performance of the rail-gun system as a whole. As in the case of conventional guns, the mechanical response of the housing under transient loading (magnetic pressure) can lead to disturbances of the projectile trajectory due to momentum transfer. However, in the case of rail guns, these disturbances can be even more severe as the armature performance can be very sensitive to variations of the normal forces at the contact interface. In previous developments, the structural mechanics of a rail gun with discrete supports were analyzed using the conventional boundary conditions. In this paper, further considerations are focused on describing a specific distributed energy storage (DES) operation technique which was developed at ISL. Using the finite-element technique, numerical calculations were performed for the ISL rail-gun EMA3 equipped with a one-stage DES. Its caliber was 15 mm \times 30 mm and produced a typical muzzle velocity of up to 1600 m/s, as well as peak currents of about 600 kA. Three spatially different DES configurations were used. The obtained results were then compared to the conventional breech-fed configuration. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel double-projectile railgun, which can launch two projectiles synchronously. This salvo performance can improve the hit rate and the destructive power on the target. The railgun has two barrels stacked in series and is powered by a pulse power. In order to verify its salvo performance, we conducted a 3-D eddy current electromagnetic field simulation with the finite-element numerical method. The simulation results showed that the self-inductance gradient (L^\prime) of each pair of rails is not always constant; the value depends on the armatures' position, particularly when the armatures are closer to the breech. Moreover, we found that, when the two armatures are at different positions, the values of the mutual-inductance gradient of the two pairs of rails (M12^{\prime}, M21^{ \prime}) are different (M12^{\prime} \neq M21^{\prime}). Subsequent circuit simulation of the launching process showed that the propulsive force acting on the armature in the front is less than that on the armature behind. We discovered that the configuration of the railgun will facilitate the synchronization during the launching process, even if the two armatures have different masses, move under different frictions, or start at different positions. We further tested a corresponding scale model of the railgun. The experiment led to the conclusion that the double-projectile railgun has good salvo performance. [ABSTRACT FROM AUTHOR]

This paper builds a field model of induction coil gun based on finite-element and boundary-element coupling method (FE-BECM). The fundamental of FE-BECM is introduced, and it is used in open-boundary eddy-current problem to prove its validity and find a way to reduce a nonconforming error. In the coil gun's FE-BECM model, the coil and projectile are discretized by finite elements; boundary elements are used to discretize the free space and associate unconnected finite-element regions. In FE-BECM model, the coordinates of nodes that belong to moving bodies change when movement occurs. The distribution of magnetic flux density and eddy current during the launch process is displayed. The result of FE-BECM is compared with experimental data and results of other numerical methods. [ABSTRACT FROM AUTHOR]

This paper describes the mechanisms by which brittle materials are penetrated by impacting projectiles, links ballistic performance to fracture behavior, and in turn to microstructure, and suggests a route unexplored previously for achieving better armor materials. Fracture patterns on cross sections through partially penetrated glass and ceramic targets show that deep penetration proceeds by the crushing and subsequent flow of fragments away from the projectile path. Preliminary finite element simulations indicate the likely positive effect of increasing frictional flow resistance of fragments. Tests are envisioned for measuring crush and fragment flow behavior, showing the effects of microstructural variables, guiding mathematical models, and hence leading to a capability to design computationally improved armor materials and structures. [ABSTRACT FROM AUTHOR]

Uncontained aircraft engine failure can cause catastrophic damaging effects to aircraft systems if not addressed in the aircraft design. Mitigating the damaging effects of uncontained engine failure and improving the numerical modeling capability of these uncontained engine events are crucial. In this paper, high strain rate material behavior of one of the most extensively used materials in the aircraft industry is simulated and the results are compared against ballistic impact tests. Ballistic limits are evaluated by utilizing explicit finite-element (FE) simulations based on the corresponding ballistic impact experiments performed at different material thicknesses. LS-DYNA is used as a nonlinear explicit dynamics FE code for the simulations. A Johnson–Cook material model with different sets of parameters is employed as a thermo-viscoplastic material model coupled with a nonlinear equation of state and an accumulated damage evaluation algorithm for the numerical simulations. Predictive performance of the numerical models is discussed in terms of material characterization efforts, material model parameters, mesh sensitivities, and effects of stress triaxiality. It is shown that mesh refinement does not necessarily provide better results for ballistic limit simulations without considering and calibrating these interrelated factors. Moreover, it is shown that current models that can only fit a specific function for damage evaluation as a function of stress triaxiality are not always successful in predicting failure, especially if the state of stress changes significantly. [ABSTRACT FROM AUTHOR]

Abstract: Numerical simulations of oblique-angle penetration by deformable projectiles into concrete targets are performed in this paper by using the three-dimensional finite element code LS-DYNA, into which a combined dynamic constitutive model which can simultaneously describe both the compressive and tensile damage of concrete is implemented. As a consequence, the ballistic trajectories and the depths of penetration under different oblique angles (from 10° to the ricochet angle) are obtained. Moreover, the damage distribution of concrete after oblique penetration is procured, which can really reflect the tensile and compressive damage of concrete. The numerical results for the depths of penetration are compared with experimental data obtained by previous authors and show good agreement. [Copyright &y& Elsevier]

The present paper deals, for the first time, with a simulation-driven study of oblique impact of jacketed ogival-nosed projectiles on mild steel target plates. The predictability of analysis results is verified against test residual velocities reported by earlier investigators [7]. The impact velocities considered here are in the range of ~800-850 m/s. Finite element modelling is carried out by discretizing target plate with shell elements and projectile with solid elements. The effects of strain rate on plate material behaviour are incorporated using available data on strain rate sensitivity of yield and ultimate strengths of various grades of steel. Using an explicit LS-DYNA solver, convergence of residual velocity is shown with respect to plate element size for normal as well as oblique angles of impact. In addition to predicting residual velocities, the current simulation procedure is also able to realistically represent plate failure modes such as perforation with dishing, erosion of copper sheath of hardened steel core projectile, and minimum angles of projectile ricochet for plates of different thicknesses. The study concludes with the presentation of a semi-empirical relation, based on the shear plugging mode of plate failure, which appears to predict well projectile residual velocities for both normal as well as oblique impact. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines the penetration and perforation of fibre-reinforced plastic (FRP) laminates struck by rigid projectiles with different nose shapes within a wide range of impact conditions using ABAQUS/Explicit code. It is assumed that the FRP laminate target response can be represented by a velocity dependent forcing function which eliminates discretizing the target as well as the need for a complex contact algorithm. The forcing function is then applied to the surface of the projectiles as boundary conditions in the numerical model. With this combined analytical and computational technique we can obtain the depth of penetration, residual velocity, ballistic limit, transient response in terms of time-histories of displacement/penetration, velocity and deceleration of the projectile. It is shown that the model predictions are in good correlation with available experimental data. [Copyright &y& Elsevier]