# Numerical Analysis and Experimental Test for the Development of a Small Shaped Charge
## 4 Model Validation, Results and Discussion  
At the beginning, numerical analyses were carried out for two extreme variants of the shaping charge displacement against the target. Numerical analyses of the propagation of the shaped charge in the Euler domain and for the penetration of the steel block were carried out. A graphical summary of the subsequent steps of the analysis for two variants was obtained. The results are presented in Table 5.  
Table 6 shows a cross-sectional comparison view of a steel block that has been subjected to a shaped charge for experimental and numerical tests. The obtained values of the penetration depth of the shaped charge in the steel block were compared with the results of the experimental study. Table 7 presents the quantitative results of the penetration depth obtained through numerical analyses and experimental tests. For the charge placed closest to the target, a large-diameter hole was obtained at the entrance of the charge into the material, with a small diameter at its end. In the case of the load placed over the longest standoff from the target, the hole has a more regular shape with a diameter taper toward its end. As can be seen from the obtained cross-sections and numerical analyses, the displacement of the charge from the target causes the shaped charge that hits the target to be formed better, which translates directly into the effectiveness of its penetration. Figure 4: View of two variants of the shaped charge model: (**a**) charge closest to the target and (**b**) charge farthest from the target. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Cross-Section of Steel Target for 7.5 mm** & **Cross-Section of Steel Target for 70 mm** \\
**Standoff** & **Standoff** \\ \hline \hline \end{tabular}
\end{table} 
Table 6: View of the section of the steel block after shooting with the shaped charge for experimental and numerical tests. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Time** & **Penetration Process for 7.5 mm Standoff** & **Penetration Process for 70 mm Standoff** \\ \hline T = 0 ms & & \\ T = 0.01 ms & & \\ T = 0.05 ms & & \\ T = 0.5 ms & & \\ T = 0.5 ms & & \\ T = 0.5 ms & & \\ T = 0.5 ms & & \\ T = 0.5 ms & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: View of the propagation process of detonation products and the penetration process of the shaped charge inside the steel target. By analyzing the obtained results of the hole depth in the steel block material, it is possible to notice a double penetration value for the charge away from the target. This difference results from the different focusing of the stream of the shaped charge. The distance of the cumulative charge from the target is a very important parameter because its proper selection makes it possible to maximize the energy transferred to the obstacle by the cumulative flux [26] and at the same time reduce energy losses to the environment, thus increasing the effectiveness of the work done by the charge. To investigate more accurately the effect of moving the charge away from the target on the penetration capabilities of the shaped charge, numerical simulations were carried out for all six variants of the removal of the charge from the target. The variants corresponded to a six-step adjustment by means of a system of teeth and sleeves connecting the load casing with the distance sleeve. The following variants of the analyses were implemented:  
* Variant 1--7.5 mm standoff closest to the target. * Variant 2--20 mm standoff. * Variant 3--32.5 mm standoff. * Variant 4--45 mm standoff. * Variant 5--57.5 mm standoff. * Variant 6--70 mm standoff farthest from the target. Table 8 shows the results of the impact of the shaped charge for all six variants for the analysis times t = 0.1 ms, 0.25 ms and 0.5 ms.  
Based on the obtained values of the maximum penetration of the shaped charge in the steel block, the characteristics of the dependence of the puncture efficiency depending on the distance between the charge and the target were determined.