Xuepeng Zhang

In order to study the damage characteristics of shaped charge jet to multilayer thin targets under water, the damage mechanism of shaped charge jet penetrating into multilayer thin targets underwater was analyzed by combining numerical simulation with experimental verification. By comparing the difference in penetration results between water and air, the mechanism of multi-damage element synergy in the process of penetration was revealed. The research showed that the damage ability of underwater shaped charge jet is significantly enhanced compared with that in air, and its damage process is mainly composed of shaped charge penetrator penetration, shock wave effect and cavity expansion effect. Based on the Held formula, the mathematical model of radial reaming of projectile penetrating into multilayer thin targets under water is established. An underwater damage experiment involving a shaped charge jet was conducted, and the action law of shaped charge projectile penetrating multilayer thin target under water was obtained. The numerical simulation, experimental results and mathematical model are in good agreement, which verifies the mathematical model of radial reaming of shaped charge projectile penetrating into multilayer target under water. The results of this study can provide technical support for the underwater protection of ships.

In order to explore the energy dissipation mechanism of shaped charge jet in underwater forming process. The finite element model of shaped charge jet underwater forming was established, and the difference of energy distribution of shaped charge jet in water and air was analyzed. Based on the virtual origin theory, the key time parameters of shaped charge jet fracture and fusion were introduced, and the theoretical model of energy dissipation of shaped charge jet underwater forming was established. The shaped charge jet underwater forming experiment was designed and carried out, and the changes of shaped charge jet shape and cavity were captured. The results show that the formation process of shaped charge jet in water can be divided into three stages: continuous stage, rupture stage, and fusion stage. Compared with air medium, the jet shape formed in water is quite different, and the jet velocity of shaped charge is 12% higher than that in air. The energy of shaped charge jet decays exponentially after entering the water, and 63% of the energy is consumed in a short time after entering the water, and then tends to be stable. The relative error between numerical solution, theoretical model, and experimental results is less than 15%, showing good consistency. The theoretical model can predict the energy dissipation under the shaped charge jet.

The study of explosion loadings in cabin structures is of great significance for evaluating structural damage. At present, most studies focus on the characteristics of explosion loadings in a single cabin. However, there are few studies on the loading characteristics of adjacent cabins under multi-cabin explosions, and there is no calculation model for calculating the load of adjacent cabins. In order to study the pressure loading characteristics of the adjacent cabin during an internal explosion, a simplified calculation model of the adjacent cabin load was constructed. The adjacent cabin environment was constructed by clamping the perforated baffle between the two cabins. The opening area of the perforated baffle accounts for 3%, 5%, 15%, and 20% of the area of the baffle. The pressure loadings of the adjacent cabin were measured by an implosion test in the adjacent cabin. A finite element simulation calculation was carried out for the test conditions. The results show that the rise time of the quasi-static pressure is in good agreement with the test results. Based on the above research, the pressure loading characteristics of the adjacent cabin were determined. A simplified model of pressure change during the pressure relief process from the explosion cabin to the adjacent cabin was obtained. Assuming an exponential decay process during pressure venting, a theoretical method for calculating the rise time of quasi-static pressure in adjacent cabins was derived. Compared with the experimental value, the maximum error is 15.9%, which can realize the prediction of the quasi-static pressure rise time of the adjacent cabin during the internal explosion. This calculation method can provide load input for internal explosion damage assessment of the complex structure of the multi-cabin.

To study the variation law of the penetration power of energy-concentrated jets on target plates with different yield strengths under lateral disturbance, a finite element model of the dynamic penetration of energy-concentrated jets was established. Targets with different yield strengths (355 MPa–1275 MPa) were analyzed under conditions from low speed (100 m/s) to high speed (400 m/s). The dynamic penetration morphology of the jet, the dynamic failure mode of the target plate and the dynamic penetration depth of the jet were analyzed. The influence law of the target plate strength on the dynamic penetration of the jet was analyzed by introducing the offset angle as a parameter and combining it with the dynamic penetration depth of the jet. Based on dimensional analysis, a prediction model for the dynamic penetration performance of the jet that considered both the lateral disturbance velocity and the strength of the target plate was obtained. A test of the dynamic penetration of the jet based on the rocket trolley was designed and carried out. Experiments were conducted to determine the dynamic penetration of the jet through target plates with different yield strengths under different lateral disturbance velocities, and the corresponding data were obtained. The reliability of the numerical simulation and of the prediction models was verified. The research results show that the jet offset angle under different yield strengths increases with the increase of the lateral disturbance velocity. When the lateral disturbance velocity is held constant, the size of the offset angle is negatively correlated with the yield strength of the target plate. The results of the prediction model, numerical simulation and dynamic penetration test were compared and verified. It was found that the three showed good consistency and that the prediction model could estimate the dynamic penetration depth of the jet with respect to the strength of the target plate.

Due to the sensitivity of the shaped charge jet to standoff and the complexity of its impact under lateral disturbances, this study aims to investigate the dynamic impact evolution of the jet influenced by standoff and lateral disturbances. A finite element model for the dynamic impact of shaped charge jets was established. Dynamic impact experiments were designed and conducted to validate the effectiveness of the numerical simulations. Utilizing dimensional analysis, a predictive model was developed for jet dynamic impact considering the combined effects of target plate strength, standoff and lateral disturbances. The results indicate that as the standoff varies between 90 mm and 225 mm, the dynamic impact depth of the jet decreases approximately linearly with increasing standoff. Meanwhile, for lateral disturbance velocities ranging from 100 m/s to 400 m/s, the impact depth decreases exponentially with increasing lateral relative velocity of the target. The lateral disturbance velocity is identified as the primary factor influencing jet impact, while the standoff is a secondary factor. The agreement among computational results, numerical simulations, and experimental outcomes confirms the accuracy and effectiveness of the predictive model and simulations, providing a basis for evaluating the dynamic impact potential of shaped charges.

Aiming at the dynamic penetration process of a shaped-charge jet, we proposed a mathematical model for the penetration of a jet under dynamical conditions based on the theory of virtual origin and the Bernoulli equation taking into account the jet and target intensities. The dynamic penetration process of the jet was divided according to the penetration channel of the jet into the static target. The dynamic penetration model of the jet based on the unperturbed section and perturbed section was established. The penetration depth variation in the shaped-charge jet vertically penetrating target plates with different moving speeds (150~400 m/s) was analyzed by finite element software. The dynamic penetration model shows that with the increase in the target moving speed, the disturbed time of the jet continuously advances, and the dynamic penetration depth continuously decreases; as the velocity of the target increases, the penetration length of the unperturbed jet decreases and then becomes stable, while the penetration length of the perturbed jet decreases. The results showed that the mathematical model is consistent with the finite element simulation, and that the mathematical model can effectively characterize the penetration depth of the unperturbed and disturbed jet portions, adequately explain the dynamic response behavior of the jet penetrating a moving target, and effectively predict the dynamic penetration depth of the jet under the influence of the target movement.

The incorporation of reactive material damage element technology in ammunition warheads is a research hotspot in the development of conventional ammunition. The research results are of great significance and military application value to promote the development of high-efficiency damage ammunition technology. In this paper, we aimed to understand the behavior of the reactive jet and its damage effect on a steel target by undertaking theoretical analysis, numerical simulation, and experimental research. We studied the influence of structural and material parameters on the shape of the reactive jet based on autodyn-2d finite element simulation software, and the formation behavior of the reactive jet was verified using a pulsed X-ray experiment. By studying the combined damage caused by the steel target penetrating and exploding the reactive jet, the influence of the structural and performance parameters, and the explosion height of the reactive jet liner on the damage effect to the steel target was studied. A static explosion experiment was carried out, and the optimal structural and performance parameters for the reactive material and explosion height of the reactive jet liner were obtained.

The authors wish to make the following corrections to this paper

Detonation waves will bypass a wave shaper and propagate in the form of a horn wave in shaped charge. Horn waves can reduce the incidence angle of a detonation wave on a liner surface and collide with each other at the charge axis to form overdriven detonation. Detection electronic components of small-caliber terminal sensitive projectile that are limited by space are often placed inside a wave shaper, which will cause the wave shaper to no longer be uniform and dense, and weaken the ability to adjust detonation waves. In this article, we design a double-layer shaped charge (DLSC) with a high-detonation-velocity explosive in the outer layer and low-detonation-velocity explosive in the inner layer. Numerical and experimental simulation are combined to compare and analyze the forming process and penetration performance of explosively formed projectile (EFP) in DLSC and ordinary shaped charge (OSC). The results show that, compared with OSC, DLSC can also adjust and optimize the shape of the detonation wave when the wave shaper performance is poor. DLSC can obtain long rod EFPs with a large length-diameter ratio, which greatly improves the penetration performance of EFP.