## 3 Experimental Results and Analysis
### Spatial Distribution of BAD in the Striking Area
Since all three EFPs can penetrate the target, the EFP diameter will have a significant influence on the radial dispersion of BAD. The radial scattering distance \(R\) reflects the radial distribution of the strike area. Based on the radial distance \(R\) of each type of fragment in the multi-layered recovery plate, a scatter diagram of the axial distance behind the target vs. the radial scattering distance was obtained (Figure 9). It should be noted that there are copper-steel bonded fragments, which are marked with a different symbol. Figure 9 shows that there are some fragments with a small \(R\) in the area beyond 1200 mm behind the target, as indicated by the pink box. The fragment penetration depth increased with increasing \(L/D\). The fragments of EFP with a large \(L/D\) (\(L/D\) = 3.86) were almost all copper in the final few layers, suggesting that the increase in the \(L/D\) mainly increased the energy of the EFP fragments near the ballistic line. Moreover, the scattering distance of the EFP fragments was the smallest versus EFPs of other \(L/D\)s; that of the target fragments was comparable. When the diameter of EFP increased from 19.18 mm to 24.73 mm, the average value of the radial scattering distance of EFP fragments increased by 61%, i.e., increasing the diameter of EFP can enhance the radial damage ability of projectile fragments. Due to the randomness in the experiment, some fragments had a large scattering distance. Overall, the radial scattering distance of most fragments was within 400 mm, and the radial scattering distance of the target fragments was larger than that of the EFP fragments. The fragment with the largest radial scattering distance was from the steel  
Figure 9: Relationship between the radial scattering distance and the distance behind the target. (a) \(L/D\) = 1.66 (b) \(L/D\) = 2.4 (c) \(L/D\) = 3.86.  
target. Thus, the target fragments were distributed in the outer layer of the BAD cloud, which is consistent with [PERSON] et al. [21]. These results indicate that with increasing the EFP diameter, the difference in the radial scattering distance between the EFP fragments and the target fragments gradually decreased. In addition, for the EFP with an \(L/D\) of 2.4, as the depth of the recovery plate increased, the overall maximum radial scattering distance of the fragments was almost unchanged in the range of 500-1100 mm behind the target. For the other two types of EFPs, although the maximum radial scattering distance was large at the beginning, the penetration depth of the fragments with a large radial scattering distance was very small. Hence, the maximum radial scattering distance gradually decreased with an increase in the depth of the recovery plate. This was caused by the gradual weakening of the energy of the fragment group by the multi-layer recovery plates. This reflects the energy attenuation process of the BAD and the radial reduction of the damaged area. Therefore, we concluded that the EFP with a medium \(L/D\) (\(L/D\) = 2.4) had a larger radial distribution range of striking area in the farther position behind the target. This was also verified by the fragment distribution on the 2D projection surface in Figure 8. An increased distance behind the target leads to greater maximum radial scattering distance of the EFP material fragments produced by the EFP with a medium \(L/D\) (\(L/D\) = 2.4), as indicated by the two red lines in the blue box. The difference in the spatial distribution of the striking area between different EFPs is caused by the varying BAD energy, and thus the uniform distribution of the striking area of the EFP with a medium \(L/D\) (\(L/D\) = 2.4) may be related to the distribution of EFP material fragment energy with respect to the scattering angle scattering angle. Therefore, it is necessary to quantitatively analyze the spatial energy distribution of the BAD.