As a natural environmental medium, soil has a wide range of sources and is often used as a material for building houses. It can also be used to construct simple protective structures in actual battlefield environments. In order to study the protective effect of sand on prefabricated fragments in practical situations, the authors conducted experiments on spherical tungsten alloy prefabricated fragments penetrating into sand using sand as the target medium. Natural sand (naturally generated rock particles with a particle size less than 4.75 mm) was selected as the sand, and the initial velocities of the fragments were 689 m/s~1761 m/s (fragment diameter 6 mm) and 596 m/s~1325 m/s (fragment diameter 11 mm), respectively. Based on the residual velocity of fragments and experimental phenomena in experimental data, the authors used LS-DYNA software to numerically simulate and compare the residual velocity of fragments and obtained a numerical model for sandy soil media and a calculation formula for the residual velocity of spherical fragments. Based on modeling equivalence in practical environments, the authors studied the impact of different attack angles on fragment trajectory deviation and found that fragments have the highest deviation values at 20° and 70° attack angles. They also analyzed the soil boundary effect within a small scale range, and the effect was significant when the vertical distance was less than 40 mm. The penetration resistance of different thicknesses of soil was calculated, and the maximum soil thickness under prefabricated fragment penetration at different speeds was obtained. The effective protective size of the soil under actual conditions was about 550 mm. This experiment provides a reference for the construction parameters of simple soil defense structures in actual environments.

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.

To explore the mechanisms of the damage to reinforced concrete (RC) frame structures subjected to internal explosions, this paper establishes a precise finite element model (FEM) of an RC frame utilizing ANSYS/LS-DYNA software 14.5. The influence of four important damage factors on the degree of structural damage is systematically analyzed. Specifically, the vertical displacement at the top center of the frame serves as the primary evaluation metric, while the four damage factors are treated as independent variables. An empty column is incorporated as an error term, facilitating a five-factor, four-level orthogonal optimization design for the simulation experiments. Based on this design, a variance analysis of the simulation outcomes is conducted. The results show that by increasing the reinforcement ratio of the beam section and reducing the charge weight, when the explosion point is located at the higher part of the building floor and near the external window, the vertical displacement of the building after the internal explosion can be reduced. The order of the influence degree of each damage factor on the damage to the reinforced concrete frame structure is as follows: explosion floor, charge weight, beam section reinforcement ratio, and explosion horizontal position.

When studying the damage law of reinforced concrete building structures under explosive loading, the direct experimental cost is too high and numerical simulations take a long time. Based on the theoretical analysis, the dimensional analysis model of reinforced concrete members under explosive loading can be used to study the damage law of reinforced concrete members under explosive loading. It provides guidance, reduces the number of tests, improves the efficiency of the test, and has certain research significance. In this paper, a typical reinforced concrete column is taken as the main research object. Based on the dimensional analysis method, the relationship between the damage to the reinforced concrete column and the explosion equivalent and explosion distance under explosion loading is studied. The finite element simulation software LS-DYNA 18.2 is used to determine the function relationship between the disturbance in the column and the proportional explosion distance. The results show that when the proportional explosion distance Z is greater than 0.0693 m/kg^1/3, the center disturbance of the blasting surface of the reinforced concrete column has a linear relationship with the reciprocal of the proportional explosion distance. The linear relationship can be used to predict the column’s center disturbance under partial explosion conditions, which provides guidance for studying the damage criterion of reinforced concrete under explosion loading.

A micro-unmanned aerial vehicle (UAV) swarm has high flexibility and intelligent unmanned flight and stealth capabilities. Moreover, it can attack both single and group targets, which will occupy dominant positions in the future information war. To satisfy the new micro-UAV swarm information combat mode and contribute to the advances in ammunition flexibility, efficiency, miniaturization, and multipurpose applicability, a 10 mm caliber micro-shaped charge warhead was designed in this study. The results indicate that the micro-shaped charge can be assembled with a micro-UAV swarm to efficiently damage the targets without relying on the weapon launch velocity. To realize a lightweight and high-efficiency micro-shaped charge structure, the formability of Teflon, nylon, polycarbonate (polycarb), and metallic copper liners was studied using the finite element analysis. The penetration efficiencies of different micro-jets on gelatin targets were compared and analyzed. It was found that the micro-shaped charge nylon and Teflon jets could pass through the gelatin target and transfer more energy to it compared with copper. The observed penetration aperture was also larger. Although the penetration depth of the polycarb jet to the target was the smallest, the penetration aperture was the largest. The findings of this study can serve as a basis for the development of micro-shaped charge technology.

In order to study the influence of the forest environment on the killing power of prefabricated fragments, the relationship between the wood medium in the forest and the residual velocity of prefabricated fragments and a simple calculation model were obtained. The impact test of 300 mm thick pine target plate was carried out with 6 mm and 11 mm diameter tungsten alloy spherical fragments. The LS-DYNA finite element modeling of wood was carried out and compared with the experimental parameters, which verified the reliability of the numerical simulation method on the residual velocity of fragments. Based on this, a simple mathematical calculation method for the forest environment is constructed to calculate the penetration track length of fragments in the forest environment. Combined with the model and the formula for calculating the residual velocity of wood, the impact of forests on fragments within a certain radius can be evaluated. According to the characteristics of the forest environment, the boundary effects of the multi-layer spacing targets and trees were further studied. The research shows that the wood reduces the fragment power mainly by affecting the penetration length. The influence of forest density, tree diameter, and other parameters on the fragment velocity attenuation in the forest environment is analyzed. Using this method, the influence of forest environmental parameters on fragment dispersion parameters can be simply evaluated.