## 4 Results and Analysis
### Effect of Transverse Bulkheads on Bend Damage  
When the transverse bulkheads are located in the potential bend zone, this will obviously have a greater influence on the bend and creases. When the transverse bulkheads are located outside the potential bend zone, this may also have some influence. Therefore, to investigate the transverse bulkhead's effect on the bend damage characteristics of SHGs, the internal structure was redesigned based on the SHG used in the validation. Figure 10 presents the SHG configuration diagram. The origin of the coordinate is located in the center of the bottom plate, and the arrangement of the transverse bulkheads is symmetrical about the yoz coordinate plane. By changing the position, eight kinds of SHGs are designed, as shown in Table 4. The numbering rules are as follows: SHG is the abbreviation of simplified hull girder, and the number in brackets is the dimensionless position of transverse bulkheads \(x^{*}\). The calculation formula of \(x^{*}\) is:  
\[x^{*}=\frac{2|x|}{L}. \tag{9}\]  
For example, SHG(0) indicates that the transverse bulkhead is located at the mid-section; SHG(1) indicates that the transverse bulkhead coincides with the end plate, i.e., there is no transverse bulkhead. Through the structural response results of SHGs with the staggered and orderly distribution of transverse bulkheads, the bearing effect of transverse bulkheads can be analyzed to some extent. Figure 10: Schematic diagram of SHG. Figure 9: Rotation angle and its differential of side plate’s sides. To study the bend damage patterns, all SHGs were subjected to the same load conditions as the verification experiment. After checking the results, the unbent SHGs were allowed to bend to a certain extent by keeping the charge unchanged and gradually reducing the detonation distance. The final calculation cases are shown in Table 5.  
There are several obvious different bend characteristics in the calculation results. These in clude whether the position is central or off-center, whether there are one or two bends, and whether the size is affected by the transverse bulkheads. Figure 11 shows the crease evolution process of the bend position with the following characteristics: (a) size is not affected by the transverse bulkheads and there is a single center bend, (b) size is affected by the transverse bulkheads and there is a single center bend, (c) size is affected by the transverse bulkheads and there is a single off-center bend, and (d) size is affected by the transverse bulkheads and there are double off-center bends. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Number** & **SHG** \\ \hline SHG(0) & & \\ SHG(0.1) & & \\ SHG(0.2) & & \\ SHG(0.33) & & \\ SHG(0.4) & & \\ SHG(0.6) & & \\ SHG(0.8) & & \\ SHG(1) & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Number of SHGs with different transverse bulkheads. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Case** & **Structure** & **Charge/kg** &
\begin{tabular}{c} **Detonation** \\ **Distance/m** \\ \end{tabular} & **SF/(kg\({}^{1/2}\)/m)** \\ \hline
1 & SHG(0) & 0.01 & 0.25 & 0.180 \\
2 & SHG(0.1) & 0.01 & 0.25 & 0.180 \\
3 & SHG(0.2) & 0.01 & 0.25 & 0.180 \\
4 & SHG(0.33) & 0.01 & 0.25 & 0.180 \\
5 & SHG(0.4) & 0.01 & 0.25 & 0.180 \\
6 & SHG(0.6) & 0.01 & 0.25 & 0.180 \\
7 & SHG(0.8) & 0.01 & 0.25 & 0.180 \\
8 & SHG(1) & 0.01 & 0.25 & 0.180 \\
9 & SHG(0.1) & 0.01 & 0.20 & 0.225 \\
10 & SHG(0) & 0.01 & 0.20 & 0.225 \\
11 & SHG(0) & 0.01 & 0.15 & 0.300 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Calculated cases. When the transverse bulkheads are located outside the bend zone, it is difficult to effectively limit the crease formation process. The crease expansion is only affected by the hull plates, as shown in Figure 11a. When the transverse bulkheads are located in the bend zone, the creases are limited between the two transverse bulkheads, the space available for side plate deformation becomes small, and the overall bend resistance is effectively improved, as shown in Figure 11b.