压装工艺对CL-20基炸药性能及聚能破甲威力的影响

利用常温成型和热压成型两种工艺制备了典型的CL-20基混合炸药装药,测试了其装药密度、密度均匀性、力学性能、爆速,计算了格尼系数。对Φ50mm标准聚能装药进行了破甲试验。验证了不同压装工艺条件下装填CL-20基炸药装药聚能射流对45号钢靶的侵彻深度和穿孔直径效果。结果表明,与常温成型CL-20基装药相比,热压成型工艺条件时装药的密度提高不小于1.46%,密度均匀性、爆速和格尼系数和破甲能力试验数据均有不同程度的提高,且Φ50mm标准聚能射流对45号钢靶的平均穿深从310mm提高至343mm,平均穿孔直径由18.0mm增至23.5mm。     

Penetration Cutoff Velocities of Shaped Charge Jets

The maximum depth of penetration, P_max, of a shaped charge jet can theoretically be calculated from 5 quantities for the purely continuous, or for the initially continuous and then particulated, or for the fully particulated penetrating jet. These quantities are the distance Z₀ of the target plate from the virtual origin, the value of γ (i.e. the square root of the ratio of target to jet density), the jet tip velocity v_j,0 the efficient residual velocity v_j,min, and the particulation time t_p. Instead of calculating the individual values of v_j,min for the individual depths of penetration P_exp at various standoff distances, this quantity can quite simply be read from the standoff diagram by means of the penetration cutoff lines- a so-called Standoff/Cutoff-diagram -, using the experimentally determined depth of penetration P_exp. The penetration cutoff lines are lines which start at the virtual origin and which represent the ideal increment in depth of penetration per jet velocity interval in the standoff diagram, the abscissas of this line corresponding to the jet tip velocities. The methods are demonstrated and explained, using the results of three firings with one type of shaped charge as an example. The shots were made at 6, 12, and 24 calibers standoff distance, and the cratering history was also determined in these trials.     

Determination of the crater radius as a function of time of a shaped charge jet that penetrates water

The new technique of measuring radial expansion of a crater as a function of time on a shaped charge jet that penetrates water is explained in this paper. Radial expansion of the crater in the frame of experimentation can, in this case, be easily described with a modified Bernoulli equation under the condition that target strength is weak, the initial radial crater velocity is equal to the axial crater velocity and that the pressure p diminishes from the initial impact pressure p₀, with the ratio of the area a to the initial area a₀ of the impacting jet.     

Calculation of Depth and Crater Diameter for the Supersonic Penetration of Shaped Charge Jet into Concrete

Considering that the sound velocity of concrete is lower than that of metal, this study discusses the effect of stationary shocks and compression during the process of shaped charge jet penetration into concrete when the penetration velocity is greater than sound velocity. The linear relationship between shock velocity and particle velocity is used to describe concrete materials. The state parameters of concrete under shock loading are calculated using Rankine‐Hugoniot jump conditions. Moreover, a combination of these relations with the Bernoulli equation yields a supersonic penetration equation across the shock. A cavity growth equation based on the Szendrei‐Held equation is presented when supersonic penetration occurs. Predictions from the supersonic penetration model are in good agreement with the depth and cavity diameter of experimental results for shaped charge jet penetration into concrete for charge diameters of 60, 142, 200, and 400 mm.     

Study on Rubber Composite Armor Anti‐Shaped Charge Jet Penetration

The process of rubber composite armor anti‐shaped charge jet (SCJ) penetration was divided into four parts based on jet deformation that occurred when the SCJ penetrated the rubber composite armor. Results on the interference speed interval, interference frequency, and surplus penetration capability of the SCJ with the rubber composite armor were derived based on the stress wave and the Kelvin‐Helmholtz instability theory. The effects of rubber layer thickness and obliquity of the armor for the composite armor anti‐SCJ penetration were studied through theoretical, X‐ray, and depth of penetration experiments. The results showed that when the obliquity was at 60° and the rubber layer thickness was in the range of 3 mm to 3.5 mm, the rubber composite armor seriously disturbed the stability of the SCJ. Thus, the rubber composite armor was found to have the best protection capability under these specifications.     

某成型装药射流的数值模拟与射流转化率

应用LS-DYNA及示踪点处理技术,对某一球锥罩成型装药结构的射流形成过程及射流侵彻靶板过程进行了研究,获得了有效射流沿其运动方向的速度分布、头部速度、侵彻孔几何描述等多项评估射流微元性能的重要参数。计算结果表明,对于普通强度钢质目标靶,在射流侵彻靶板过程中,常规小锥角药型罩产生的有效射流为2000m/s以上的射流段,杆式射流的临界侵彻速度值为1400m/s,从而进一步得到其射流转化率为29.65%。     

药型罩切分方式对射流形成影响的数值模拟

为了研究药型罩切分方式对其形成射流性能的影响,利用数值模拟软件ANSYS/LS-DYNA对横向切分和纵向切分的药型罩以及未切分药型罩在爆轰波作用下形成射流的过程以及对45号板的侵彻能力进行了数值模拟,比较了不同切分方式的药型罩在爆轰波作用下形成射流的形状、头尾部速度、拉伸长度和抗拉伸性能及其对45号钢板的侵彻能力。结果表明,在相同装药条件下,横向切分药型罩相比纵向切分药型罩的头部速度提高约220m/s,且抗拉伸性能更好,对45号钢板的侵彻深度提高约3.26cm;横向切分药型罩相比未切分药型罩的头部速度提高约360m/s,对45号钢板的侵彻能力提高约5.62cm。     

Theoretical Study of a Diesel‐Filled Airtight Structure Unit Subjected to Shaped Charge Jet Impact

Diesel composite armor has high penetration resistance and can be used in tank vehicles to improve their protective capability and increase fuel oil storage. This study provides a theoretical calculation method to investigate the interaction between a shaped charge jet and a diesel‐filled airtight structure unit. Disturbance theory can predict the part of the jet that is disturbed by diesel fuel. The lumen radius for the container was varied to study its influence on the disturbance capability. A great lumen radius is found to cause lower maximum and minimum speeds of the disturbance velocity range of the jet, as well as a narrower disturbance velocity range. The reliability of the theoretical results was validated by experiments, and the experimental data show good agreement with the theoretical results.     

The use of analytical computer models in shaped charge design

This paper briefly examines some of the more challenging aspects of shaped charge design, such as control of jet breakup and analysis of the jet's interactions with targets. Background material and experimental observations are provided for analytical models uniquely describing and providing insight into these research areas. Analytical codes incorporating these models can now predict the performance of a shaped charge against various targets. An example of a shaped charge designed using an analytical computer code in order to match its capability against a range of targets is presented and discussed.     

Numerical simulation of the formation of shaped-charge jets from hemispherical liners of degressive thickness

The formation of shaped-charge jets from hemispherical copper liners of degressive thickness (decreasing from apex to bottom) is analyzed by numerical simulation of a twodimensional axisymmetric problem of continuum mechanics. The comparison was based on the parameters of the jet formed from a modern standard shaped charge with a conical liner which provides penetration of a steel target to a depth equal to 10 charge diameters. The comparative analysis was performed using calculated mass–velocity distributions and the ultimate jet length–velocity distributions obtained on their basis, from which the potential penetrability of jets was evaluated. It is shown that the shaped-charge jets formed by hemispherical shaped-charge liners of degressive thickness are comparable in head velocity and penetrability to the jets from conical liners.     

Determination of the Velocity Difference between Jet Fragments for a Range of Copper Liners with Different Small Grain Sizes

A range of small calibre shaped charge copper liners were manufactured experimentally by the electro‐deposition technique. The average grain size of the produced copper liners was determined using the SEM technique. The specific breakup time, which represents the velocity difference between the particulated jet neighboring fragments (V_PL), was determined for the range of copper liners of different grain sizes using Zerelli‐Armstrong constitutive model. The specific breakup time and the total number of the jet fragments were studied over the range of grain size and the predicted jet temperature.     

Breakup Time of Zirconium Shaped Charge Jet

The Johnson‐Cook parameters for the zirconium material were determined based on the data obtained from the tensile testing of zirconium specimens at different strain‐rates and different temperatures. The velocity difference (V_PL) between the particulated jet fragments was calculated for zirconium liners of different thicknesses using Johnson‐Cook constitutive equation. A breakup time formula for the zirconium shaped charge was proposed, which demonstrated better ductility performance than the copper shaped charge.     

The Natural Spread and Tumbling of the Shaped Charge Jet Segments

The collapse mechanism of the shaped charge jet prevents the formation of a jet, the segments of which move in a straight line with absolute accuracy, even under the assumption that the shaped charge is ideally symmetrical. This is a result of the fact that the jet break-up mechanism already starts at the collapse stage, in which the liner material has a big transversal velocity component. A model for calculating the distribution of the angle by which the jet segments' direction of movement deviates from the shaped charge axis of symmetry (the spread angle) is presented in detail. The tumbling frequency of the segments as a function of their velocity and final length is also predicted by the theory. The predictions made by applying the model to the standard 83.8 mm 42 degrees opening angle B.R.L. precision shaped charge were found to be consistent with the data published in open literature. The comparison of these predictions with the data leads also to the conclusion that the cutoff in the copper jet penetration into steel targets occurs when the jet segments start to hit the walls of the already formed hole instead of reaching its bottom without being disturbed on their way.     

Theoretical Study on Equivalent Target of Ceramic Composite Armor

The theory of equivalent target was studied by considering the standoff curve and the penetration model of the horizontal velocity method to analyze the equivalent mechanism of spaced target equating ceramic composite armor. This theory can forecast the penetration ability of the escape jet. The equivalent target model can be obtained after the structure of the shaped charge and armor as well as the relationship between the armor and the shaped charge is confirmed. The experimental results confirmed the forecast accuracy of the theoretical model.     

Shaped charge jet interaction with Highly Effective Passive Sandwich Systems - experiments and analysis

The development and investigation of reactive sandwich targets and their interaction with shaped charge jets is one of the many research areas, where important contributions were made by Manfred Held. Such reactive sandwiches are known to be extremely effective against jets, but have a number of disadvantages. In this work, the interaction of the copper jet from a shaped charge calibre 136 mm with a double sandwich system, each sandwich consisting of a non-reacting layer between outer steel plates, is investigated. In 10 experiments with identical geometrical setup, only the material of the non-reacting layer is changed. Using flash X-ray pictures, the interaction of the jet with the sandwich system is investigated. Evaluation of these pictures as well as the comparison of the measured residual penetrations behind the sandwich target clearly demonstrate the influence of the material of the inner sandwich layer. The deformation and movement of the steel plates, caused by the penetrating jet, can be seen in the X-ray pictures. It is shown that it is possible to distort a shaped charge jet so that its penetration capability behind the target is reduced to a minimum. A fully three-dimensional hydrocode simulation of the experiments enabled the jet/sandwich interaction and steel plate deformation and rupture to be studied in detail.     

The Tip Origin of a Shaped Charge Jet*

This study demonstrates that the pex portion of a typical 42° conically lined shaped charge is not being efficiently utilized. In fact, approximately 40% of the liner height at the apex end of the cone does not provide an efficient jet as far as penetration depth is concerned. In this paper, we present an experimental and theoretical study of the liner apex. First, a series of experiments were conducted in which liner apices were filled to various heights to inhibit the collapse of the apex portion of the liner. Next, a one-dimensional analytical shaped charge model was used to simulate the filled cone experiments. From these experiments and calculations we have determined that approximately 30–40% of the cone height is used to produce a compact tip particle rather than a stretching jet. This indicates that i t may be possible to redesign the apex portion of the liner to achieve a more efficient use of liner height.     

Effect of Moving Plate on Jet-Penetration

Effect of a moving plate between a shaped charge jet and the target on jet-penetration has been investigated theoretically. It has been assumed that the plate moves undeformed with uniform velocity, and jet-penetration in the plate or the target occurs hydrodynamically so that the impact of the jet produces a hole in the plate whose diameter is bigger than that of the jet. The free passage of the jet through this hole is intercepted when the jet touches the wall of the hole due to its transverse motion. The presence of a moving plate between the jet and the target has been found many times more effective than that of a stationary plate in reducing the jet penetration in the target. The effect of angle of attack, velocity of the plate and initial distance between the plate and the target on penetration, produced by the jet going out of the plate, has been investigated for a typical set of arbitrarily selected values of jet and plate parameters.     

Copper-Tungsten Shaped Charge Liner and its Jet

The use of copper-tungsten alloys for shaped charge liners leads to an improving of the jet penetrability into an homogeneous steel target. In comparison with copper jets, the penetration depth can be increased by a factor 1.3. The improving is due to the increasing of both the density and the break-up time. Copper-tungsten shaped charge jets and their aspect of break-up were investigated by flash radiography. Both the effect of rotation of copper-tungsten jets and their standoff performance were examined.     

Studies on jet formation and penetration for a double-layer shaped charge

An analysis for liner collapsing and jet/slug formation of a double-layer shaped charge (DLSC) is presented. Variations of the collapse angle, collapse velocity, and jet velocity of the DLSC are discussed. Numerical simulations based on the Lee-Tarver model are performed to have an insight into the jet formation. Ballistic tests are conducted using a conical (60°) metal liner 56 mm in diameter to have a contrast with an ordinary shaped charge jet. It is shown that the collapse angle and velocity are both increased by the convergent detonation wave in the DLSC. The jet velocity, kinetic energy, and ballistic capability are significantly increased by using the DLSC, and the DLSC is an efficient way to improve shaped charge performance.