## 2 Experimental Preparations  
### Test Specim and Scenario  
In the present study, a simple curved plate without stiffeners under longitudinal compression, as shown in Figure 1, is considered for the tests. The dimensions of the cylindrically curved plates are length (a), breadth (b), thickness (t), and flank angle (\(\theta\)). The breadth (the length of an arc in a cylindrically curved plate) is kept constant at 400 mm throughout the experiment and throughout the finite element analysis.  
To investigate the ultimate strength characteristics of the curved plates and obtain an experimental database, three main variables (i.e., flank angle, thickness, and aspect ratio) are considered. In cylindrically curved plates, the flank angle is the most important parameter. The breadth and flank angle are related by the following relationship:  
\[b=R\theta \tag{1}\]  
where \(R\) is the radius of the curved plate. Three values (2000 mm, 4000 mm, and 8000 mm) extensively used in merchant vessels were selected for the radii. In addition, the aspect ratios in the range of 1.0 to 2.0 and thickness in the range of 6 mm to 8 mm were considered. Based on these main parameters, the experimental scenario is summarized in Table 1. According to this scenario, a series of buckling collapse tests was carried out on a total of 72 plates (two tests for each scenario), consisting of 54 curved plates and 18 flat plates under longitudinal compression. The displacement control mode was used for the buckling experiment. In addition, 1 mm/min loading speed of the universal testing machine (UTM) was considered.  
Tensile tests were performed to apply the precise values of material properties. Generally, the chemical composition of the material has a dominant influence on its mechanical properties. The specimens for material tensile tests were extracted from the plate for buckling collapse tests. In the present study, six tensile tests were performed in accordance with American Society for Testing and Materials (ASTM) standard A370. Figure 2a shows the representative tensile testing specimens with three different thicknesses, and Figure 2b shows the preparation of the material tensile tests. Table 2 shows the chemical composition of the selected material, and Table 3 shows the summary of the material tensile tests.  
Figure 1: (**a**) Schematic of a cylindrically curved panel and (**b**) plate.  
Figure 2: (**a**) The representative tensile testing specimens with three different thickness and (**b**) image of the test jig.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Test Model** & **a/b (b = 400 mm)** & **t (mm)** & **R (mm)** \\ \hline F01 & & & 0 \\ C01 & & & 2000 \\ C02 & & & 4000 \\ C03 & & & 8000 \\ \hline F02 & & & 0 \\ C04 & & & 2000 \\ C05 & & & 4000 \\ C06 & & & 8000 \\ \hline F03 & & & 0 \\ C07 & & & 2000 \\ C08 & 2.0 & 8 & 4000 \\ C09 & & & 8000 \\ \hline F04 & & & 0 \\ C10 & & & 2000 \\ C11 & 1.5 & 6 & 4000 \\ C12 & & & 8000 \\ \hline F05 & & & 0 \\ C13 & & & 2000 \\ C14 & & & 4000 \\ C15 & & & 8000 \\ \hline F06 & & & 0 \\ C16 & & & 2000 \\ C17 & & & 4000 \\ C18 & & & 8000 \\ \hline F07 & & & 0 \\ C19 & & & 2000 \\ C20 & & & 4000 \\ C21 & & & 8000 \\ \hline F08 & & & 0 \\ C22 & & & 2000 \\ C23 & & & 4000 \\ C24 & & & 8000 \\ \hline F09 & & & 0 \\ C25 & & & 2000 \\ C26 & & & 4000 \\ C27 & & & 8000 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Chemical compositions of the target material.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**No.** & **Thickness** & **Yield Strength** & **Tensile Strength** & **Elongation** \\ \hline
1 & 6 mm & 364 MPa & 491 MPa & 32\% \\
2 & 6 mm & 345 MPa & 478 MPa & 35\% \\
3 & 7 mm & 332 MPa & 475 MPa & 37\% \\
4 & 7 mm & 342 MPa & 475 MPa & 36\% \\
5 & 8 mm & 333 MPa & 464 MPa & 37\% \\
6 & 8 mm & 343 MPa & 476 MPa & 35\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Mechanical properties of the curved plate.