Shaped Charge Liner Research Articles

Effect of Zn and Ni added in W–Cu alloy on penetration performance and penetration mechanism of shaped charge liner

Explosive experiments of W–Cu–Zn, W–Cu–Ni and W–Cu alloy shaped charge liners (SCLs) were conducted, and the effects of Zn and Ni added in W–Cu alloy on the penetration performance and penetration mechanism of the SCLs were systematically investigated. Results show that Zn and Ni evidently reduce the penetration performance of the SCLs. Microscopic analyses show that the affected zones in the targets are enlarged and the melting of W particles in the jets is aggravated, which indicates the transverse dissipation of the jets energy. Thus, the decreased penetration performance of the SCLs is mainly caused by the severe transverse dissipation of the jets energy. During the penetration process, the addition of Zn in the W–Cu alloy decreases the melting point of the matrix, making the matrix easier to be melted and squeezed out. The lubrication effect of the matrix is reduced severely and the interaction between the W particles and the targets is facilitated. The addition of Ni in the W–Cu alloy increases the melting point of the matrix phase, making the matrix phase harder to be melted and the lubrication effect of the matrix decreased. The reduced lubrication effect leads to severe interaction between the jets and the targets, and the transverse dissipation of the jets energy is aggravated. Moreover, the addition of Ni in the W–Cu alloy increases the bonding strength between the W particles and the matrix, thus during the penetration process, W particles of the W–Cu–Ni jets have severer deformation compared with that of the W–Cu jets. The severer deformation of the W particles leads to further consumption of kinetic energy.

Penetration performance of W/Cu double-layer shaped charge liners

Two kinds of W/Cu double-layer shaped charge liner (SCL) were prepared by chemical vapor deposition (CVD) combined with electroforming technique: A SCL with W inner layer and Cu outer layer, B SCL with Cu inner layer and W outer layer. The penetration properties of A and B SCLs were researched. The results show that the two SCLs can form continuous jet and the tip velocities of A and B jets are 7.4 and 6.3 km·s−1, respectively. The kinetic energy density (5.3 × 1011 J·m−3) of A jet tip increases by 194.4 % compared with that (1.8 × 1011 J·m−3) of B jet tip. B jet, however, exhibits deeper penetration depth at the same experimental conditions. The chemical component and microstructure of the area nearby the ballistic perforation were researched. Component analysis shows that both the jets are formed only from inner layer metal. Microstructure analysis shows that martensite and intermetallic form around ballistic perforation penetrated by A SCL due to the intensive interaction between W jet and steel target. The two kinds of newly formed ultrahard phases also hinder the jet from penetrating target further. As a result of relatively alleviative interaction between Cu jet and target, only solid solution rather than ultrahard phases forms around ballistic perforation penetrated by B SCL.

Effect of Temperature on Microstructure and Deformation Mechanism of Fe-30Mn-3Si-4Al TWIP Steel at Strain Rate of 700 s−1

As twinning-induced plasticity (TWIP) steel is one potential material for shaped charge liner due to the combination of high strength and high plasticity, deformation mechanism at high strain rate and high temperature is required to study. Compression experiments of Fe-30Mn-3Si-4Al TWIP steel were conducted using a Gleeble-1500 thermal simulation machine and a split-Hopkinson pressure bar (SHPB) between 298 and 1073 K at strain rates of 10−3 and 700 s−1, respectively. Microstructures were observed using optical microscopy (OM) and transmission electron microscopy (TEM). Results show that flow stress and densities of deformation twins and dislocations decrease with increasing deformation temperature at strain rates of 10−3 and 700 s−1. The stack fault energy (SFE) values (Γ) of Fe-30Mn-3Si-4Al TWIP steel at different temperatures were calculated using thermodynamic data. Based on corresponding microstructures, it can be inferred that at 700 s−1, twinning is the main deformation mechanism at 298–573 K for 30 mJ/m2⩽Γ⩽63 mJ/m, while dislocation gliding is the main deformation mechanism above 1073 K for Γ⩾ 145 mJ/m2. In addition, with increasing strain rate from 10−3 to 700 s−1, the SFE range of twinning is enlarged and the SEF value of twinning becomes higher.

Numerical analysis of the effect of the geometric parameters of a combined shaped-charge liner on the mass and velocity of explosively formed compact elements

The formation of high-velocity compact elements of shaped charges with a liner of a combined hemisphere-cylinder shape has been analyzed by numerical simulations of a two-dimensional axisymmetric problem of continuum mechanics. The influence of the radius and thickness of the hemispherical portion of the combined liner on the parameters of the compact elements has been studied. It is shown that in implosion of hemispherical liners whose thickness decreases from top to bottom, there is an increase in the velocity of the resulting jet flow. When using a hemispherical portion of variable thickness (to increase the velocity of the compact elements formed), it is necessary to solve two additional problems—to implement timely separation of the head part of the jet flow with increased velocity and increase its mass. For this, it is proposed to use the jet-forming part of the combined liner in the form of a truncated sphere or a slightly elongated ellipsoid of revolution. Combined shaped-charge liners in the form of a truncated ellipsoid of variable thickness were developed, allowing the formation of compact elements having a velocity of 7.5–10 km/s.

Shaped Charge Liner Early Collapse Experiment Execution and Validation

AbstractA novel experiment developed for researching the initial collapse of an aluminum shaped charge liner was designed, executed, and validated. The experiment evolved from the need to recover shocked liner material to enable the analysis of relationships between microstructure and early liner collapse behavior. The research required material that had been shocked, yet was sufficiently intact to allow for metallurgical examination. Additionally, the experiment was designed to replicate the unique shock loading of shaped charge liners. Practically, the experiment had to be inexpensive to perform. The paper describes the experimental design, execution and validation and presents practical examples of the utility of the output. The experimental design is based on recreating a unique shock front, halting the deformation within a few microseconds and recovering material suitable for examination. Validation of the experiment employs a combination of available hydrocode modeling data and shaped charge liner collapse theory. The data collection supporting the validation was performed with computed tomography (CT) and laser generated 3D imagery. The output is recovered material valid for study.

The properties of the sintered copper powder liner

In order to study the properties of sintered copper powder shaped charge liner, the copper powder, whose particle size was below 20 μm, was chosen as the main material. The mixed powders were directly pressed into the desired shape of the shaped charge liner by the top direct-pressure way. The microscopic morphology of the spinning shaped charge liner, the sintered and non-sintered powder liners, and the particle properties of the copper powder were studied with scanning electron microscopy. The experimental results showed that the irregular copper powder could get together effectively and sintering could improve the compactness of the powder liner effectively. The wall thickness and density of the non-sintered and sintered liner were also tested, and it shows that sintering causes the wall thickness thinned and the density improved. The penetration depths of non-sintered powder liner, sintered powder liner and the spinning copper plate liner were tested with different standoff respectively, showing that the penetration properties of sintered powder liner are well.

Dynamical Penetration Simulation of Solid Target under Shaped Charge Liner

A finite element model of rock mass under linear conical shaped charge liner including explosive, metal liner, air and rock mass is built. The ALE algorithm is applied to simulate the penetration characteristic of rock mass and analyze the influencing factors such as the cone angle, the wall thickness of metal liner, and the standoff distance. Fluid-structure coupling condition is used between metal liner and air as well as between air and rock mass. The present results show that LS-DYNA can be well used to simulate the progress of jet formation and rock penetration with the transmission and focusing of shock stress wave. The different cone angles, wall thicknesses of the metal liner, and the standoff distances will influence the penetration effect.

Numerical Simulation of a Circumferential Cutting Warhead about Anti-Light Armor

In order to improve the block area and damage probability to targets, a new type warhead of circumferential cutter is presented. The optimization simulation is designed for the circumferential cutter warhead by using LS-DYNA finite element software. The detonation mode and the liner curvature radius are two important factors, which influence the formation process of circumferential cutting warhead. The result shows that priority should be given to use the upper and lower ends at the same time blasting technique. The shaped charge liner curvature radius and shot elevation ratio should be controlled in between 0.9 and 1.1.The warhead can be envisaged to achieve the desire of circumferential cutting.

Investigation of a Nickel-Aluminum Reactive Shaped Charge Liner

A nickel/aluminum (NiAl) reactive powder system has been investigated to determine its mechanical properties under quasi-static and high rate compression to understand its deformation behavior. A shock recovery system has been used to define shock reaction thresholds under a triaxial loading system. Two nickel/aluminum (NiAl) shaped charge liners have been fired into loose kiln dried sand to determine whether the jet material reacts during the formation process. A simple press tool was developed to press the liners from a powder mixture of nickel and aluminum powder and a simple conical design was used for the liner. The shaped charge jet particles were recovered successfully in the sand and subjected to a detailed microstructural analysis. This included X-ray diffraction (XRD) and optical and electron microscopy on selected particles. The analysis demonstrated that intermetallic NiAl was detected and all the aluminum was consumed in the particles examined. In addition, different phases of NiAl were detected as well as silicon oxide in the target material. There was also some evidence that the aluminum had melted along with evidence of a dendritic microstructure. This is the clearest evidence that the shaped charge jet material has reacted during the formation process. Simulations have been performed using the GRIM Eulerian hydrocode to compare with flash X-rays of the jet.

Numerical and Experimental Investigation of Jet Formation and Particulation in Shaped Charges with Tulip-like Steel Liners

In this study, performance of steel lined tulip shaped charges is investigated numerically and experimentally. Certain statistical methods such as Design of Experiment and Neural Network method are implemented in order to decrease the time required for the investigation of various parameters affecting the output of different shaped charge liners. Numerical simulations of jet formation and penetration of steel targets are performed and they are compared with the experiments including images of shaped charge jets taken by Flash X Ray systems.

Experimental Investigations on Aluminum Shaped Charge Liners

In this study, performance of aluminum lined shaped charges are investigated experimentally. Liners having different thicknesses (4%, 6% and 8% Charge Diameter) and geometries (conical and trumpet) with different alloy compositions (5000, 6000 and 7000-series aluminum alloys) are tested against steel and sand targets at large (~15 CD) and moderate (~3 CD) standoff distances in order to obtain penetration performances. In addition, the jet characteristics are determined using Flash X-Ray radiography technique.

Sintering effect on the performance of tungsten-copper powder liner

In order to study the properties of high-temperature sintered tungsten-copper powder shaped charge liner, the tungsten powder and copper powder, whose particle size is below 20 μm, were chosen as the main material. The mixed powder were directly pressed into the desired shape of the charge liner by the top direct-pressure way. The microscopic morphology of the spinning shaped charge liner, and the particle properties of the copper and tungsten powder were studied with scanning electron microscopy. The experimental results showed that the irregular copper powder and regular tungsten powder both are effectively and hightemperature sintering, which can improve the compactness of the powder liner effectively. The wall thickness and density of the no sintered and sintered liner were tested, showing that sintering thinned down the wall thickness and improved the density. The penetration depth of no sintered powder liner, sintered powder liner and the spinning copper plate liner were respectively tested in different standoff, showing that the penetration properties of sintered powder liner are well.

Effect of interaction mechanism between jet and target on penetration performance of shaped charge liner

The penetration properties of pure W, W–Ni–Fe alloy and W–Cu alloy shaped charge liners (SCL) against steel target were researched. The results show that all the SCLs can form continuous jets with close tip velocities. W–Cu SCL, with the lowest density, exhibits the deepest penetration depth. Microscopic analysis show that ultrahard phases of Fe0.95W0.05 and martensite formed around ballistic perforations in targets penetrated by W and W–Ni–Fe SCLs. The ultrahard phases hinder jets from penetrating target further. For W–Cu SCL, Cu cannot form intermetallic with W or Fe, inhibiting intense interaction between jet and target. Consequently no ultrahard phases are observed in target penetrated by W–Cu jet. Moreover, Cu phase can lubricate the interface between jet and target, making W–Cu jet penetrate target easily. All of above results prove that the penetration depth of SCL is not only decided by the density and velocity of jet, and the interaction between jet and target is also an important factor to influence the penetration performance of SCL. Thus the interaction between jet and target should be taken into consideration for predicting the penetration performance of SCL.

Numerical Simulation on Bifurcate Fracture of Linear Red Copper Penetrator

The Red copper has been widely used in shaped charge liner because of good ductility. Red copper penetrator is a Linear Explosively Formed Penetrator (LEFP) when linear red copper shaped charge liner overturned under the effect of detonation production. Compared with ordinary jet swords, red copper penetrator has a wider range of stand-off, bigger cratering and significant aftereffect, which can meet the requirements in various environments. It was observed that bifurcate fracturing of red copper penetrator occurred in the performance testing of LEFP initiated on edge midpoint as the stand-off increased, which resulted in the separate craters on the target and the cratering effect was weakened. The Propagation of detonation wave and the interaction with red copper shaped charge liner were theoretically and experimentally studied, also numerical simulations were conducted. The results showed that velocities of charge liner elements were directly proportional to those of detonation waves, which caused different velocity directions and values of different elements, and great velocity gradient formed in the penetrator. The penetrator fractured as the elongations both on the vertical and horizontal directions were greater than the dynamic elongation of red copper. It was concluded that the main factor which resulted in the bifurcate fracture phenomenon was velocity gradient in the penetrator.

The Porosity of Liner Effect on the Shaped Charge Jet Penetration

Shocking temperature rise of the shaped charge with porous liner before collapse was calculated based on the Herrman equation of state. Shaped charges with 36mm charge diameter were used to fire at the 603 armor steel target, the penetration-standoff curves(P-S) of the shaped charge liner with 88.6% and 90.3%T.D were measured and compared. It is shown that proper porosity is helpful to lengthen the jet break up time and penetration depth，which is of significance for the application of porous liner.

Shaped Charge Patents 1942-1952: From Optimism to Solutions

In the 1940s, the majority of research in America into shaped charge technology was performed by the US military and government laboratories. Information was largely classified. Shortly after the US Army declassified some details of this technology, extensive research and testing began in many American companies. Along with this came the filing of several patents. These US patents from the early years of shaped charge design reveal a transition from an almost naive optimism over the nascent technology to solutions for oilfield issues. A focus on the early claims and the issues with carriers and charge detonation reveals much in this regard. The Early Years—Optimism and Uncertainty A patent filed by E.I. du Pont de Nemours and Company in 1942 (2399211) typified the wave of optimism of shaped charge capabilities (this was not too unexpected, for du Pont manufactured the charges) (Fig. 1). Liners for the charges were not required, stated the document, but if they were present the metal slugs (“carrots”) produced from the detonation would be “projected at very high velocity through the perforation and into the adjacent strata.” In other words, the liner remnant was a positive consequence of the detonation. The patent also advocated the use of plastics or cardboard materials for the carrier, stating that the charge “may or may not be enclosed in a watertight container…they are generally insensitive to the action of water and impervious thereto.” Two years later, another du Pont patent (2605703) described a “novel and improved explosive device.” The document provided many details about shaped charge liners, but admitted that an understanding of why the devices worked was unclear and speculated the penetration was due to “pulverizing, molecular fragmentation or abrasion.” Even the liner was considered a contributing factor in the “net destructive effect,” but the patent admitted it “was not possible to determine this.” A Gulf Research and Development Company patent filed in 1945 (2494256) proposed a panoply of shaped charge configurations—as if to cover all possible uses. The document mentioned “numerous results of our experiments” that verified the penetrating power of the lined shaped charge and revealed the charges should be “provided with a suitable cover to pre vent any liquid entering the cavity (the liner).” The patent optimistically predicted that a slug would be “sufficiently small to pass through the hole in the casing and come to rest deep in the formation where it has negligible effect on the flow of fluids through the hole.”

Effects of Mesh Size and Target Dimension on Numerical Simulation of Shaped Charge Liner Penetration into Target

In order to solve two problems when simulating the phenomenon of Shaped Charge Liner penetrating into target, an example was simulated to study the influence of mesh size and target dimension on the penetration results using AUTODYN-2D. The relationship between the Shaped Charge Liner parameters and the critical dimension of the target was gained．The effects of mesh sizes on the penetration depth, aperture，and calculation time were studied. After analyzing the simulation results，a proper range of mesh size was obtained. The simulation results agree well with the test results. The research could provide reference on the simulation of Shaped Charge Liner.

The Bifurcate Fracture Analysis of Linear Red Copper Penetrator

Red copper has been widely used in shaped charge liner because of its good ductility. Red copper penetrator is the Linear Explosively Formed Penetrator (LEFP) with some length and energy which has been produced when linear red copper shaped charge liner is overturned under the effect of detonation production. Compared with some ordinary jets sword, it has some characteristics such as the broad range of stand-off, big cratering and obvious rear effect and may meet with many operating requirements in different environment. It has been discovered that the bifurcate fracture phenomenon of red copper penetrator will occur with the increase of stand-off when it is initiated on edge midpoint in its property test experiment, and results in the separating cratering on the target which influences its effect. The Propagation characteristics of detonation wave in explosive and the effect of detonation wave on red copper shaped charge liner are analyzed, and then the velocity change obtained by each element and the velocity relationship between each element are studied. So it can be drawn a conclusion that the velocity gradient is the main factor which results in the bifurcate fracture phenomenon of red copper penetrator. In addition, the theoretic analysis model of the bifurcate fracture in red copper penetrator is built. On the basis of modeling analysis and calculation, the criterion of the occurring bifurcate fracture and the measures avoiding the bifurcate fracture are put forward. The results agree well with that of experiments.

Effect of external magnetic fields on shaped-charge operation

This paper deals with electromagnetic actions that allow one to control the shaped-charge effect at different stages of shaped-charge operation. A decrease in penetration of the shaped-charge jet is attained by production of an axial magnetic field in the shaped-charge liner immediately before shot, and production of a magnetic field in the conducting target material that is transverse to the direction of jet propagation. The considerable decrease in the penetration capability of the charge observed in the experiments is attributed to a sharp amplification of the magnetic field in the jet formation region upon liner collapse. The effects accompanying the “field pumping” prevent the normal formation of a shaped-charge jet. A model of magnetic field generation in a conducting medium subjected to high-velocity deformation with particle elongation along the magnetic flux lines is considered. X-ray photographs of shaped-charge jets formed from a “magnetized liner” are given. Theoretical calculations have shown that deformation conditions that can provide for intense magnetic field generation also arise during high-velocity jet penetration into a conducting target across the flux lines of the initial magnetic field previously produced in the target.

Microstructural evolution in electroformed nickel shaped-charge liners with nano-sized grains undergone deformation at ultrahigh strain rate

Nickel shaped-charge liners with nano-sized grains were prepared by the electroforming technique, and the deformation at ultrahigh strain rate was performed by explosive detonation. The as-formed and post-deformed microstructures of electroformed nickel shaped-charge liners with nano-sized grains were observed by means of transmission electron microscopy, and the orientation distribution of the grains was analyzed by the electron backscattering pattern (EBSP) technique. The melting phenomenon in the jet fragment and the recovery and recrystallization in the slug after plastic deformation at ultrahigh-strain rate were observed in the ultrafine-grained nickel shaped-charge liners. The research evidence shows that dynamic recovery and recrystallization play an important role in plastic deformation at ultrahigh strain rate.