## 5 Analysis of Selected Design Variants of the Considered Structure
### Solution V: Fillet  
Solution V optimizes structural details by designing fillets at the connection between the side wall panel and the support, aiming to reduce the stress concentration caused by sharp angles. The fillet radius is set to 5 mm, as shown in Figure 25e. The simulation results after adjusting the structure, as shown in Table 14, lead to the following conclusions:  
1. Deformation Analysis: In the Z direction, as the wall thickness decreases, the amount of deformation gradually increases, particularly in the 1.5 mm thickness, where the deformation is the greatest. This indicates that, while the rounded corner design aids in controlling deformation to some extent, its effectiveness is limited for thinner wall thicknesses. 2. Stress Analysis: The 2.5 mm thickness exhibits relatively low stress in the Z direction, indicating that the rounded corner design effectively reduces stress concentrations in thicker wall thicknesses. The stress in the Z direction significantly increases for the 2.0 mm thickness, suggesting that the rounded corner design does not sufficiently alleviate stress concentrations in medium thicknesses. The 1.5 mm thickness shows the highest stress in the Z direction (6.7582 MPa), indicating that, despite the rounded corner design, stress concentration remains a significant issue in the thinnest wall thickness. Solution V, as a structural detail optimization measure, plays a certain positive role in enhancing the stability of the box-type substation structure and reducing stress concentrations. However, as the thickness decreases, the effectiveness of the optimization in controlling the maximum deformation and stress gradually diminishes. The simulation analysis of various structural optimization solutions for box-type substations highlights key insights into enhancing structural stability and reducing stress \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Thicknesses** & **Response** & **X** & **Y** & **Z** & **XZ** & **ZY** \\ \hline \multirow{3}{*}{2.5 mm} & Von Mises Stress (MPa) & 0.5293 & 0.3024 & 3.8951 & 3.9014 & 3.8951 \\  & Total Deformation (mm) & 0.054082 & 0.054972 & 1.1523 & 1.1536 & 1.1523 \\  & Von Mises Stress (MPa) & 0.23713 & 0.30283 & 3.9926 & 3.9992 & 3.9926 \\  & Total Deformation (mm) & 0.055864 & 0.055014 & 1.1532 & 1.1545 & 1.1532 \\  & [PERSON] Stress (MPa) & 0.72434 & 0.30298 & 4.007 & 4.0136 & 4.007 \\  & Total Deformation (mm) & 0.056786 & 0.055097 & 1.1553 & 1.1567 & 1.1553 \\ \hline \hline \end{tabular}
\end{table} 
Table 13: Combination simulation results of three thicknesses under Solution IV. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Thicknesses** & **Response** & **X** & **Y** & **Z** & **XZ** & **ZY** \\ \hline \multirow{3}{*}{2.5 mm} & [PERSON] Stress (MPa) & 0.75156 & 0.36199 & 2.6087 & 2.6124 & 2.6087 \\  & Total Deformation (mm) & 0.2321 & 0.067577 & 1.1568 & 1.1581 & 1.1568 \\  & [PERSON] Stress (MPa) & 1.7812 & 0.022959 & 5.3453 & 5.3549 & 5.3453 \\  & Total Deformation (mm) & 0.28641 & 0.0021908 & 1.1803 & 1.1817 & 1.1803 \\  & Von Mises Stress (MPa) & 0.68539 & 0.0049452 & 6.7582 & 6.7717 & 6.7582 \\  & Total Deformation (mm) & 0.29483 & 0.001683 & 1.1615 & 1.1628 & 1.1615 \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Combination simulation results of three thicknesses under Solution V.  
concentration. Although all solutions aim to enhance structural stability and reduce stress concentrations, their effectiveness varies depending on the wall thickness and the specific directional stresses they address. Specifically, Solution I significantly improves stability and reduces stress concentrations in thicker walls, particularly effectively in the Z and XZ directions. Solutions II and III are especially effective in reducing stress and controlling deformation in thinner walls. However, they exhibit limitations in thicker walls, where stress concentration remains an issue despite reinforcement.