Shaped Charge Jet Penetration Research Articles

Research Status and Development Trend of Tandem Armor-Breaking Warheads

In order to cope with the continuous progress of tank protection technology, it is imperative to optimize and improve the ability of existing armor-breaking warheads. This paper mainly introduces the development history of explosive reactive armor, shaped charge jet formation theory, shaped charge jet penetration theory, armor-breaking warhead technology, series armor-breaking warhead technology and research status of armor-breaking/killing compound warhead technology. Finally, the development trend of armor-breaking warhead in the future is described, in order to provide some enlightenment for the design and improvement of armor-breaking warhead in the future.

Numerical modeling of shaped charge jet penetration into ceramic–metal double-layered medium using smoothed particle hydrodynamics

The prediction of the damage effects of shaped charge projectile to ceramic–metal multi-layered target is a challenging task to address. In this paper, the smoothed particle hydrodynamics (SPH) method is applied to simulate the penetration of the metal jet generated by the shaped charge detonation into ceramic–metal double-layered plates. The presented SPH model incorporates different equations of states. Moreover, the elastic-perfectly plastic constitutive model and the Johnson–Holmquist-II material constitutive model were employed for modeling the mechanical behaviors of the solid materials in this study. Firstly, simulation of the high velocity impact process of a ceramic ball on a ceramic–metal double-layered plate was conducted to validate the presented constitutive model. After the validation of the numerical model, simulations of penetration of a shaped charge into a double-layered ceramic–metal plate by using millions of SPH particles were conducted. The simulation results (perforation diameter and debris cloud) are in good agreement with the available experimental data, which shows that our in-house SPH solver is capable of tackling the shaped charge detonation and its penetration into multi-layered structures very well. Furthermore, the presented SPH model can reproduce different types of fracture patterns observed in experiments and their dynamic formation processes.

Penetration and Cratering of Steel Target by Jets from Titanium Alloy Shaped Charge Liners.

In order to enlarge the crater diameter of shaped charge jet penetration into steel targets, this paper investigates the penetration and cratering characteristics of steel targets by shaped charge jets from titanium alloy liners. Titanium alloy shaped charge liners are prepared separately with mechanical processing and selective laser melting (SLM), and pulsed X-ray radiography is used to identify jet formation characteristics. Jet formation is numerically simulated by AUTODYN-3D, and steel target penetration tests are carried out at a short jet stand-off distance. The results show that AUTODYN-3D can realistically simulate jet formation from titanium alloy liners and that the SLM-processed liner exhibits better penetration performance than the mechanically processed liner. The existing cratering formula of jet penetration is modified to make it consistent with the aperture variations of jet penetration from titanium alloy-lined shaped charges at a short stand-off distance. The findings of this study are expected to provide technical and theoretical support for research on the penetration characteristics of the jets from titanium alloy-lined shaped charges.

Rock Dynamic Fracture Characteristics by Mini-Linear Shaped Charge Jet Penetration: A Case Study

An insignificant number of studies have focused on employing penetration using mini-linear shaped charge jets for directionally controlled splitting of massive rocks. In this study, we adopt a numerical calculation method to simulate the penetration and formation of the main splitting surface of a concrete specimen, considering a wedge angle of 45° in both processes. The surface on the principal axial plane is found to split first due to linear jet penetration. In the case of single primary-plane splitting, cracks appear at both ends of the long axis of the penetration crack and the splitting surface extends diagonally from the center of the penetration. A transverse crack separates the splitting surface and the radial-fracture surface, and the degree of fracture decreases along the direction of the height of the specimen. Finally, a realistic physical model demonstrating penetration using a mini-linearshaped charge jet is established. It is a rapid and safe blasting technology to handle hazardous massive rocks during emergency rescuing or mining.

Effect of fragment impact on shaped charge jet formation and penetration into steel target

Purpose This paper aims to investigate the effects of fragment impacts to shaped charge warheads in terms of shaped charge jet formation geometries and penetration performances. Design/methodology/approach In experimental process, a fragment was accelerated to a shaped charge warhead by means of a powder gun to a velocity more than 1,000 m/s, and this impact led to conical damage in the explosive of the warhead. Deformation on the warhead was visualized using X-ray technique to observe holes generated during fragment impact. Penetration test was performed against AISI 1040 steel plates with the damaged shaped charge warhead. Penetration performance of shaped charge jet, which deviated from the symmetry axis, was simulated by using SPEED software with 3-D Eulerian method to validate the numerical modelling method by comparing penetration test and simulation results of damaged warhead. Findings Simulation and test results showed good correlation for the warhead in terms of penetration depth and hole geometry at the impact surface of steel plates. In addition, the effects of the numbers and the geometries of fragment holes on shaped charge jet penetration performances were investigated with validated numerical methods. Simulation results showed that the increase in the number of fragment holes in the explosive of the warhead led to particulation of shaped charge jet that diminished penetration depth in the target plate. Additionally, simulation results also showed that the fragment hole geometry in the explosive after different fragment impact angles affected the amount of jet deviation from the symmetry axis as well as penetration depth in the target plate. Practical implications The results obtained from the current study revealed that fragment impact angle and different number of fragment impact reduced the penetration performance of shaped charge warhead by influencing the symmetry of shaped charge jet negatively. Originality/value The current study fulfils the need to investigate how fragment impact on the shaped charge warhead affect the formation symmetry of shaped charge jet as well as penetration performance by experimental and numerical methods. Penetration performance result of asymmetric jet is compared by experimental and numerical studies. A detailed methodology on numerically modelling of the effect of fragment impact angle and number of fragment impact on shaped charge jet performance is given in this study.

Experimental and Numerical Study on the PG-7VM Warhead Performance against High-Hardness Armor Steel.

Analyses presented in the article were carried out in order to characterize the main parameters of the shaped charge jet formed due to detonation of the PG-7VM warhead. As opposed to the previously published studies in which rolled homogeneous armored steel was mainly used as a target, in the current work the warhead penetration capability was determined against more contemporary high-hardness (500 HB) ARMSTAL 30PM steel armor with precisely determined mechanical properties. The research included experimental depth of penetration tests and their numerical reproduction in the LS-Dyna software. Special attention was paid to factors that could perturbate the shaped charge jet formation process and under- or overestimate its penetration capability. For this reason, warheads were X-ray inspected for structural discrepancies (voids or air inclusions in explosive, misalignment between the body, explosive, and liner, or lack of contact between the explosive and the liner) and properties of materials (explosive, targets, and most important warhead components) were analyzed before the experiments. The numerical model of the warhead was defined more accurately than in previously published studies, since it was based on the real grenade dimensions and its technical documentation. Thanks to this, the depth of penetration of the target made of ARMSTAL 30PM armored steel plates by the shaped charge jet formed from the PG-7VM warhead obtained by numerical simulation was consistent with the experimental results and equaled 278 mm and 280 mm, respectively. The difference between the experimental and numerical value was smaller than 1%, which confirms that the developed methodology of modeling allows users to properly reproduce the PG-7VM shaped charge jet formation and target penetration processes. A verified numerical model of the shaped charge jet penetration into a steel target was used to determine depth of penetration in function of stand-off distance for the PG-7VM warhead. A maximum depth of penetration of about 317 mm was obtained for the stand-off distance of 360 mm, which may indicate the potential direction of modernization of warheads.

Theoretical analysis and experimental study of the performance of shaped charge jet penetration into thick-walled moving target by rocket sled testing method

This study proposes a new rocket sled testing method using a precise detonation control system to achieve the interaction process of a thick-walled moving target and a shaped charge. The shaped charge jet's penetration into the thick-walled moving target is divided into two stages by using theoretical methods. The penetration depth and hole shape of each jet element into the moving target can be accurately calculated through a virtual source point method. A disturbance criterion is proposed to judge the motion state of the jet element after impacting the side of the thick-walled moving target. The effect of the target's moving velocity on the hole shapes and the influence of the target's strength on the penetration depth is analyzed.

Interlayer Material Interactions on Shaped Charge Jet Protection Performance of Passive Armor

The process of jet interaction with oblique highly passive armor was analyzed, and the relations on energy absorbed by the interlayer material of inert cassette were presented. The bulging armors with silicon rubber and plexiglass interlayer material interacted with shaped charge jets were studied experimentally. When the jet parameters is determined, the energy deposited in the interlayer during shaped charge jet penetration is related with not only its physical dimension, such as obliquity and thickness, but also with other physical parameters, such as material density, sound velocity and material strength, et al. the shaped charge jet penetrating capability decrease 75% and 65% respectively when passed through the silicon rubber and plexiglass composite armor, which shows that the silicon rubber cassette have better protection performance.

The inhibitor effect on the shaped charge jet penetration

A submunition is one of the small shaped charges and has a severe penetration capability when it is dispensed in large numbers from the sky. Neutralizing it is one of the major interests in military science. An inhibitor which can be formed inside of shaped charge liner when a submunition impacts soft material target plays an important role to the penetration performance. A silicone rubber material that shows suitable inhibitor character of being dug deep by submunition impact in penetration mechanism was selected. The penetration performance of a shaped charge adopted inhibitors was investigated through ballistic experiments and numerical simulations. A remarkable reduction of jet penetration capability was obtained from the experiment. Numerical simulation using LS-DYNA, which is a non-linear finite element analysis code, was also carried out to reconstruct the experimental results. The simulation results showed good agreement with the experimental results, providing insights into the noticeable reduction of jet penetration performance due to a silicone rubber inhibitor.

Effects of Liquid Parameters on Liquid-Filled Compartment Structure Defense Against Metal Jet.

The effect of liquid parameters on the defense capability of the liquid-filled compartment structure (LFCS) of a shaped charge jet (SCJ) is quantified using dimension analysis of experiments on the reduced depth of SCJ penetration, which is disturbed via the LFCS with different liquids. The effects of three parameters, namely, liquid density, sound velocity and dynamic viscosity, on LFCS defense for SCJ are discussed quantitatively. Dynamic viscosity exerts the most important effect on LFCS disturbance of SCJ penetration, followed by liquid density. Meanwhile, sound velocity causes a negligible effect on LFCS disturbance of SCJ when the hole diameter in LFCSs are short. LFCSs offer excellent protection as they can significantly reduce the penetration capability of SCJ. Thus, LFCSs can be used as a new kind of armor for defense against SCJ.

Theoretical and experimental study of shaped charge jet penetration into high and Ultra-high strength concrete targets

The depth of penetration (DOP) for concrete targets generated by a jet is required to achieve a certain value, under the premise of which the crater diameter must be sufficiently large in the present design of a shaped charge. A large cavity generated by the precursor shaped charge of a tandem warhead is conducive to the penetration of the follow-through projectile. Given the rapidly developing and increasingly extensive application of high and ultra-high strength concrete (H&UHSC), which has excellent resistance to penetration, impact and blasting, shaped charge jet penetration into the targets was investigated in this study. The chase between the incoming elastic wave, plastic wave and the jet/target interface as the shaped charge jet moves into H&UHSC targets were discussed. The response regions in the target were analyzed. Four penetration stages were proposed, while the corresponding modified Bernoulli equations were established. The two-stage mechanism of cavity growth was used to describe the penetration modes. Furthermore, the DOP experiments for two different structures of shaped charge penetration into H&UHSC targets with four strength grades were conducted. The predictions of depths and hole profiles from the present model correlate with the experimental data reasonably well. Results indicate that the DOP decreases exponentially as the compressive strength of H&UHSC increases at the beginning, and then the rate of the decreasing tendency slows down gradually and approximates the limit when the compressive strength approaches 200 MPa. Moreover, the cavity diameters resulted from the jet into the H&UHSC targets exhibit insensitivity to the increasing strength grade. The jet with diverse velocity and diameter structure may experience different penetration stages as it penetrates various H&UHSC targets, which affects the penetration result.

Influence of target strength on the penetration depth of shaped charge jets into RHA targets

The effect of the target strength on the shaped charge jet penetration into Rolled Homogeneous Armors (RHA) target has been studied experimentally and numerically. It is found that the yield strength of the target can largely reduce the penetration depth of shaped charge jets. Allison and Vitali [4] formula for the prediction of jet penetration depth is modified by introducing a target resistance reduction term based on Wright and Frank analysis method [20] and Rosenberg and Dekel [19] target penetration resistance term. Furthermore, the material constant “B” in the target resistance function was optimized and found to be 0.73. A fairly good agreement with numerical and experimental results of penetration depth has been demonstrated. Results show that the increase of target yield strength leads to large decrease of the shaped charge jet penetration depth into RHA targets. The proposed target strength reduction equation is validated using both small and large caliber shaped charges against RHA targets with different strength values.

Application of Smoothed Particle Hydrodynamics in analysis of shaped-charge jet penetration caused by underwater explosion

A process of target penetration by a shaped-charge jet includes three main stages: charge detonation, formation of a metallic jet and its penetration of the target. With continuously increasing computational power, a numerical approach gradually becomes more prominent (combined with experimental and theoretical methods) in investigations of performance of a shaped-charge jet and its target penetration. This paper presents a meshfree methodology - Smoothed Particle Hydrodynamics (SPH) - for a shaped charge penetrating underwater structures. First, a SPH model of a sphere impacting a plate is developed; its numerical results agree well with the experimental data, verifying the validity of the mentioned developed method. Then, results obtained for different cases - for various materials of explosives and liners - are discussed and compared, and as a result, more suitable parameters of the shaped charge in order to increase the penetration depth are obtained - HMX and copper were chosen respectively as the explosive and the liner material. It follows by validation of a model of a free-field underwater explosion, developed to verify the effectiveness of the modified SPH method in solving problems of underwater explosion; its numerical results are compared with an empirical formula. Finally, the SPH method is applied to simulate the entire process ranging from the detonation of the shaped charge to the target penetration employing the optimal parameters. A fluid around the shaped charge is included into analysis, and damage characteristics of the plate exposed to air and water on its back side are compared.

Influence of Yield Strength of Ti-Alloy Liner on Crater Diameter Formed by Shaped Charge Jet Penetration

In order to study influence of yield strength of liner on aperture diameter when liner material has high strength, the initial aperture and final aperture diameter were analyzed by considering yield strength of liner material. The relationship of aperture diameter with liner strength changing was obtained. The experiments using Ti alloy liner with different yield strength penetrated into concrete were performed. The results shown that, the average aperture diameter of Ti alloy liner which the yield strength is 785MPa is about 1.16 times bigger than that of copper liner which the yield strength is 870MPa. It has good agreement with theoretic analysis. With liner strength increasing, the aperture diameter decreased, and this increasing is more significant with jet velocity decreasing. With respecting to the high-density copper liner, the influence of yield strength on aperture diameter is more sensitive for low-density Ti alloy liner.

The damage and failure mechanism of the concrete subjected to shaped charge loading

Abstract In this paper, the experiments of the large-size shaped charge jet penetration in concrete target were carried out. Then, the concrete target was cut off to obtain the internal structure and measure the shape of the penetration hole. Moreover, the cube concrete samples with the sizes of 100 mm length in different location of the concrete target were incised, and the material compressive strength was test by the material testing machine. The test results show that the material strength of the concrete target is enhanced with the increase of the distance to the penetration hole. Therefore, the damage of concrete target can be rough evaluated according to the compressive strength of the concrete samples. Based on the test results, the damage factor was added in the dynamic constitutive, which can describe mechanical behavior of concrete subjected to intensive impact loading was proposed. In this model, the concrete is assumed to be homogenous and consecutive in macroscopically. The results of the model were compared with the experimental results and the results which not considering the damage factor. The comparing results show that the model can be used to describe the dynamic mechanical behavior of concrete.

Numerical simulations of shaped charge jet penetration into concrete-like targets

Shaped charge jet has been widely applied in the military and energy sources’ extraction fields; while the related investigations on the shaped charge jet penetration into concrete-like target are still limited, a series of numerical simulation works are conducted in this article. Holmquist–Johnson–Cook and Johnson–Cook models are used to describe the concrete-like targets and metal liner/casing of the shaped charge, respectively. The whole process including the formation, elongation in the air, and penetration into concrete-like target of shaped charge jet is reproduced using the multi-material arbitrary Lagrange–Euler algorithm and fluid–structure interaction method implemented in LS-DYNA. Simultaneously, the striking velocities of the jet (both tip and tail) and the damage of target (diameter and depth of penetration borehole) are derived. The above constitutive models, the corresponding material parameters, and the finite element algorithms are validated by comparing with the available tests’ data. The analyses of parametric influences are further performed. It indicates that for the unfragmented shaped charge jet, the penetration depth increases and the average penetration borehole diameter decreases with the standoff distance increasing, respectively; the compressive strength of concrete target has slight influence on the penetration depth of shaped charge jet; the diameter of shaped charge jet penetration borehole with aluminum liner is larger, while that with copper liner has a deeper penetration depth. It can also be found that the influence of explosive type on the penetration performance of shaped charge jet is negligible at small standoff distance, while the explosive LX-14 performs better than explosives Octol, B, and 8701 at larger standoff distance.

A Numerical Method for the Determination of the Virtual Origin Point of Shaped Charge Jets Instead of Using Flash X-ray Radiography

ABSTRACTThe effective jet length between the virtual origin (VO) point and the target surface is very important for the calculation of a shaped charge jet penetration. A numerical approach to determine the exact position of the VO of a small caliber shaped charge jet is presented in this paper. The numerical approach includes shaped charge jet formation algorithm using explicit Autodyn solver and estimates the precise location of the VO point using the hydrocode analysis. This is particularly important when the experimental flash X-ray radiograph is not available. The proposed VO model approach was validated by firing four small caliber shaped charges against concrete targets. The maximum difference between the experimental penetration depth and that calculated using the presented VO approach was less than 4%.

Spallation affected fracture pattern of a titanium alloy plate subjected to linear shaped charge jet penetration

In this paper, the commercial finite element code LS-DYNA is employed to simulate the process of a certain kind of a linear shaped charge jet penetrating into a TC4 (Ti–6Al–4V) titanium alloy plate of moderate thickness. The fracture profiles agree well with experimental observations, which confirms the validity of the code and the Johnson–Cook material model applied to describe the TC4 plate. The fracture pattern of the plate is drawn based on this comparison.

Hydrocode simulations of liquid filled channels for understanding erosion in shaped charge jet penetration

Hypervelocity impacts of copper rods into liquid filled channels circumferentially confined by steel cylinders were investigated using 2D axisymmetric hydrocode simulations. The confined liquid was utilized as a means to investigate the interplay of eroded target material and the remaining projectile in order to elucidate relevant penetration behaviors in solid materials. This led to a better understanding of two significant contributing parameters in the flow characteristics: the density (how difficult the material is to accelerate) and the channel diameter (how far the material has to move). While the liquid eliminates direct strength effects on penetration of the rods, varying the channel width allows a survey of parameter space that is typically a function of both material strength and density. Three successive copper rods with varying velocities and delays were used to model a penetrator representative of select sections of a shaped charge jet. For each target material, the residual penetration in solid rolled homogeneous armor (RHA) was then measured as a function of the liquid channel width. A strong dependence on both the material density and channel width was observed in regards to the efficiency of the material against penetration.

Spallation Affected Fracture Pattern of a Titanium Alloy Plate Subjected to Linear Shaped Charge Jet Penetration

Spallation Affected Fracture Pattern of a Titanium Alloy Plate Subjected to Linear Shaped Charge Jet Penetration