## 4 Conclusions  
In this study, a multi-layered recovery plate was used to collect BAD from EFPs vertically penetrating steel targets. Based on the results, the spatial distribution of the striking area of EFPs with different \(L/D\)s was obtained, and the spatial energy distribution of the BAD was analyzed. The main conclusions are as follows:  
(1) In the range of 500-1100 mm behind the target, the maximum radial scattering distance of the fragments decreased with increasing distance from the target when the \(L/D\) was too small (\(L/D\) = 1.66) or too large (\(L/D\) = 3.86), thus indicating a reduction in the strike area in the radial direction. In comparison, the radial distribution of the striking area of the EFP with a moderate \(L/D\) (\(L/D\) = 2.4) was uniform, thus resulting in a larger radial distribution range of the strike area at a large distance from the target. Moreover, the radial scattering distances of the target fragments were larger than those of the EFP fragments.  
(2) With increasing \(L/D\), the total energy of the BAD and the energy of the EFP fragments both increased, and the energy of the EFP fragments account for a large portion of the total energy of the BAD. With increasing scattering angle, the average energy of the BAD did not simply decrease--it increased after 30\({}^{\circ}\) due to the effect of the spalled fragments on the back side of the target.  
(3) The differences in the spatial energy distribution of BAD formed by EFP with different \(L/D\)s was mainly concentrated in the scattering angle range of 3-17\({}^{\circ}\). The spatial distribution of the relative cumulative energy in other scattering ranges was exponential. When the \(L/D\) was too large (\(L/D\) = 3.86), the energy of the EFP fragments became concentrated in the small scattering angle range, i.e., close to the residual EFP. The energy distribution of the target fragments was indistinguishable. For the EFP with a moderate \(L/D\) (\(L/D\) = 2.4), the average energy of the fragments was evenly distributed in the range of 5-20\({}^{\circ}\), and the energy distribution of the BAD shifted towards the large scattering angle region. This led to a uniform radial distribution of the striking area within 500-1100 mm behind the target, with uniform damage to components outside the ballistic line. It should be noted that the \(L/D\) of EFP actually affected the radial dispersion of BAD through the EFP diameter. The damage assessment of armored vehicle targets and EFP warhead structural design makes it necessary to select a reasonable and moderate \(L/D\) (diameter \(D\)) to achieve the best damaging effect of the BAD behind the armor.  
The results of the present study can be used in future work to determine the zone of damage inflicted by BAD on the internal components of an armored target. Furthermore, the results lay the foundations for evaluating the damage effectiveness behind armor due to EFP penetration and provide technical references for the structural protection of the internal instruments and crew of an armored target and for EFP warhead design.  
Methodology, [PERSON] and W.L. ([PERSON]); Investigation, [PERSON] ([PERSON]), [PERSON] and G.Y.; Writing--original draft, [PERSON]; Writing--review & editing, [PERSON], [PERSON] ([PERSON]), [PERSON] ([PERSON]) and T.G. All authors have read and agreed to the published version of the manuscript. This research received no external funding.  
Not applicable.  
The experimental results are available upon request.  
The authors declare no conflict of interest.