## 3 Confirmation of Structural Data According to Dynamic Characteristics
### Performance Analysis of Fixing Clamp  
The fixing clamp uses eight arms, as shown in Figure 6, to control the displacement generated in the +Z direction of the cover. First, the performance of the fixing clamp according to the dynamic characteristics of the welding tool was checked, and the \"on/off\" interval of the arm was set such that it would not overlap with the fixing clamp when the welding tool proceeded. At this time, the \"on\" setting was the state in which the arm was in contact with the cover, and the \"off\" setting was the state in which the arm was raised to allow the welding tool to pass through. According to Figure 17, the deflection range generated by 0.3 mm in the -Z direction when the welding tool load was 1.1 tons was \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Point No.**} & \multicolumn{3}{c}{**+Z Direction Max. Displacement (mm)**} \\ \cline{2-4}  & **Thermal Load** & **1.1 ton** & **Thermal Load + 1.1 ton** \\ \hline
1 & 0.094 & 0.055 & 0.063 \\
2 & 0.086 & 0.059 & 0.071 \\
3 & 0.091 & 0.06 & 0.071 \\
4 & 0.091 & 0.058 & 0.064 \\
5 & 0.083 & 0.075 & 0.082 \\
6 & 0.099 & 0.032 & 0.065 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Comparison of +Z direction deflection data in the presence and absence of frictional heat. Figure 16: +Z directional deflection image of each point. confirmed to be at least 70 mm. For deflection occurring in the \(-\)Z direction, because the fixing clamp did not need to be on, the arm was set to be off when the gap between the welding tool and the fixing clamp reached 70 mm. Based on an analysis of the dynamic behavior of the welding tool, it was confirmed that the overall displacement generated in the +Z direction in the presence of the fixing clamp decreased, as shown in Figure 18. Moreover, Table 8 shows that the maximum displacement in the +Z direction decreased by 31% in the presence of a fixing clamp, and the overall average decreased by 39 %. These results confirmed that the fixing clamp could control the displacement generated in the +Z direction of the cover. Figure 17: Deflection range in the \(-\)Z direction under the 1.1 ton welding tool load. Figure 18: Comparison of fixing clamp application results. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Data**} & \multicolumn{2}{c}{**+Z Direction Max. Displacement (mm)**} & \multirow{2}{*}{**Decrease Rate**} \\ \cline{2-3} \cline{5-5}  & **Without Fixing Clamp** & & **With Fixing Clamp** \\ \hline Max & 0.075 & 0.052 & 31 \\ Average & 0.036 & 0.022 & 39 \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Comparison of deflection data due to dynamic behavior of welding tools. Because the performance of the fixing clamp was verified under various welding tool loads, we furthered the analysis by applying frictional heat, as shown in Figure 14, and the fixing clamp was made to come into contact with the cover by setting the arm to the on state when the frictional heat of 600 \({}^{\circ}\)C was applied. On the basis of the analysis data, the time point at which the frictional heat was 600 \({}^{\circ}\)C was selected as the effective value. As shown in Figure 13, data were obtained for six points, and to compare the results depending on whether the fixing clamp was applied, all the fixing clamps were set to the on state, regardless of the position of the welding tool. The analysis results obtained in the state where the welding tool load and frictional heat were applied simultaneously confirmed that the displacement generated by the fixing clamp in the +Z direction decreased considerably when the frictional heat was 600 \({}^{\circ}\)C, as shown in Figure 19. At 1 s, when the frictional heat was 600 \({}^{\circ}\)C, the displacement was lower than that in Figure 14, and it can be seen in Table 9 that the displacement reduction rate at each point ranged from a minimum of 31% to a maximum of 80%. The average displacement reduction rate was 61%.